Space Science	FY 1996	FY 1997	FY 1998
* Advanced x-ray astrophysics facility (AXAF)	237,600	178,600	92,200
* Space Infrared Telescope Facility	--	--	81,400
* Relativity mission	51,500	59,600	45,600
* Cassini	191,500	89,600	9,000
* Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED)	--	18,200	48,200
Payload and instrument development	25,900	16,900	12,300
* Explorers	132,200	125,000	142,700
* Discovery	102,200	76,800	106,500
* Mars surveyor	111,900	90,000	139,700
* New Millennium	43,500	48,600	75,700
Advanced space technology	143,300	132,000	151,200
Mission operations and data analysis	563,600	583,300	507,400
Supporting research and technology	239,400	246,000	311,200
Suborbital program	88,000	64,100	84,400
Launch services	245,300	240,600	236,300
Total	2,175,900	1,969,300	2,043,800

* Total Cost information is provided in the Special Issues section

Distribution of Program Amount by Installation	FY 1996	FY 1997	FY 1998
Johnson Space Center	3,600	3,600	4,100
Kennedy Space Center	5,100	9,000	9,800
Marshall Space Flight Center	356,200	307,900	202,000
Ames Research Center	94,400	71,000	79,400
Langley Research Center	8,600	9,000	15,100
Lewis Research Center	23,200	27,400	26,400
Goddard Space Flight Center	764,800	842,000	901,700
Jet Propulsion Laboratory	753,900	655,300	717,300
Headquarters	166,100	44,100	88,000
Total	2,175,900	1,969,300	2,043,800

PROGRAM GOALS

The mission of the Office of Space Science (OSS) is to seek answers to fundamental questions about:

• The Galaxy and the Universe: What is the universe? How did it come into being? How does it work? What is its ultimate fate?
• The Origin and Evolution of Planetary Systems: What was the origin of the Sun, the Earth, and the planets, and how did they evolve? Are there worlds around other stars? What are the ultimate fates of planetary systems?
• The Origin and Distribution of Life in the Universe: How did life on Earth arise? Did life arise elsewhere in the universe?

Many of the primary products of space science are intangible: knowledge and discoveries about the universe in which we live and the laws that govern it. The American public, as an investor in space science research, gains a greater understanding of the universe, inspiration at its wonders and improved education. However, the process of exploration also demands advances in technology -- such as sensors, electronics, robotics, automation, communications, and power generation and control systems -- that provide more tangible benefits to our society. Morover, new space science discoveries offer other tangible returns: for example, it may soon be possible to characterize "space weather" and its dependence on the Sun's variability. Violent space "storms," which can profoundly affect space- and Earth-based communication and transportation systems, may soon be predicted by means of Sun and solar wind monitors now under development, coupled with advanced theoretical and empirical models of the coupling of the Sun to the Earth. These intangible and tangible benefits attest to the value of space science to our Nation and the world.

STRATEGY FOR ACHIEVING GOALS

Science

The Space Science program acquires knowledge and makes discoveries by exploring. We explore physically, by means of space probes and planetary landers and orbiters. We explore remotely, by means of telescopes and other observatories, in Earth or heliocentric orbit, observing the Sun, the solar system, and the distant universe.

Space Science is exploring in order to answer questions that are as old as human thought, yet recent discoveries have generated new excitement about the origin and evolution of the Universe, and about the possibility of life elsewhere in, or beyond, our solar system. In October, 1996, three dozen biologists, planetary scientists, astronomers, and cosmologists were assembled in Washington, D.C. by NASA and the National Research Council at the request of the White House Office of Science and Technology Policy. In a workshop format, the group considered emerging directions in space science and identified "Origins" as a unifying theme for future initiatives. The conclusions of the group, some of which are summarized below, were presented to the Vice President at a symposium on December 11, 1996, at the White House. The complete findings of the group are available on the World Wide Web via http://www.hq.nasa.gov/office/oss, under the Space Summit link.

The study of Origins follows a 15-billion-year-long chain of events. The chain begins at the birth of the universe at the Big Bang, moves through the formation of the chemical elements and of the galaxies, stars and planets, continues through the mixing of chemicals and energy that cradled life on Earth, before reaching the earliest self-replicating organisms and then the profusion of life.

For the first time in history, we have achieved the level of understanding and technical capability necessary to fill in "missing links" along the chain of Origins by exploring on the Earth and outward in space, in the present and backward in time. Recent discoveries from diverse disciplines attest that life is remarkably hardy and that each step in the chain of Origins occurred surprisingly quickly. Discoveries in just the past few years provide the first scientific basis for believing that life may be widespread in the universe, in our solar system and beyond. We also have a new comprehension of the development of the

universe, its constituent galaxies and stars, the number and variety of planetary systems, and the processes that shape them. To fill in the final links, we need to understand more about the processes leading to the origin of life, about habitats suitable for life, and about the origins of the building blocks of the universe.

Understanding of the final links is within reach. Major advances over the next 15 years can be realized by continuing and building upon the multidisciplinary programs that have brought us to this point. NASA's current and planned Space Science programs begin the next steps in the quest for Origins and pose the technology challenges needed for subsequent steps. Missions now underway and in planning, including Hubble Space Telescope upgrades, the Advanced X-ray Astrophysics Facility, the Space Infrared Telescope Facility, the Stratospheric Observatory for Infrared Astronomy, the Mars Surveyor series, and other planetary and space astronomy and physics projects, will offer powerful tools for advancing the Origins program. At the same time, while the Origins challenge provides a unifying core for the Space Science program, neighboring disciplines address important problems of their own, and may unexpectedly contribute directly -- as was the case for the recent analyses of Martian meteorites. These related activities span the broad panoply of laboratory, field, and theoretical research conducted by NASA. Existing NASA planning processes, coordinated with NSF and other agencies and using peer review, are the best way to define the details and priorities of these programs.

The FY 1998 Budget request includes an increase for several Origins-related programs. These include:

• an increase for the Mars Surveyor program to allow for the launch of a Mars sample return mission in the middle of the next decade, and to increase the scientific robustness of the program;
• a new Exploration Technologies Development program, to enable bold, new, low-cost experiments on the surface of solar system bodies;
• full development of the Keck II ground-based interferometer, to enable direct detection of planets around other stars;
• an increase in astrochemistry/astrobiology research and analysis, to support the multidisciplinary study of the origin and evolution of pre-biotic material, the origin and distribution of life, the adaptation of life to space, and space studies of life on Earth.

These initiatives are responsive to the President's new Civil Space Policy, which calls for:

• A sustained program to support a robotic presence on the surface of Mars by the year 2000 for the purposes of scientific research, exploration and technology development;
• A long-term program, using innovative technologies, to obtain in-situ measurements and sample returns from the celestial bodies in the solar system;
• A long-term program to identify and characterize planetary bodies in orbit around other stars.

Investment in a balanced and diversified Origins program is expected to yield a steady return of significant findings and, inevitably, major surprises. Over the next 15 years, scientists and the public could share the excitement of discoveries such as:

• when and how primitive life emerged and flourished on Earth;
• sharp pictures of planet-forming disks, infant stars and the growth of galaxies;
• more detailed histories of the early stages of the universe, including maps of the dark matter seeds that grew to form galaxies.
  

The Hubble Space Telescope images of embryonic solar systems and the evidence for possible past life on Mars have aroused intense public interest in the Origins of the universe and its contents. These breakthroughs are the astonishing returns from years of investment in many scientific disciplines. The Origins quest informs, excites and inspires the public. Its outcome could well have as profound an effect on human thought as the Copernican and Darwinian revolutions.

Education and public outreach

In 1995 the Office of Space Science published an education and public outreach strategy. More recently, OSS and the Space Science Advisory Committee chartered a Task Force of scientists and educators to consider how this strategy should be implemented. The recommendations of the Task Force were published in October 1996, and are available in full on the World Wide Web at http://www.hq.nasa.gov/office/oss/pubs.htm. The Task Force concluded that, in order to have a significant impact on improving the quality of science, mathematics and technology education, and on enhancing public understanding of science in the United States, OSS must take a comprehensive, integrated approach. A series of one-on-one, or few-on-one, interactions between the public and OSS-sponsored scientists cannot have a significant impact. The Task Force recommended the creation of a distributed, decentralized "Ecosystem" or network for space science education to foster a wide variety of highly-leveraged education/outreach activities. The results of those activities would then be disseminated across the country.

The foundation of this "Ecosystem" is the set of participants in the Space Science program located at universities, federal and non-federal laboratories, and aerospace industries. Superimposed upon this foundation are sets of "nodes" of three different types:

• The producers of educational materials and products which draw upon the results of OSS activities. These products are in a form either directly usable or easily adaptable for use in education and public outreach;
• The archivers/disseminators of educational products who ensure that such products are known, widely available, and easily accessible;
• A set of brokers/facilitators who aggressively search out high-leverage opportunities for education/outreach; arrange alliances between individual scientists or scientific teams and educators to realize those opportunities; and help the space science community turn results from missions and research programs into educationally appropriate products which can be distributed nationally.

In many cases, existing institutions are in a position to take on one or more of these roles, so that limited OSS resources can be directed toward value-added activities rather than toward the creation and maintenance of institutions. In practice, the system envisioned by the Task Force starts with the identification of an educational need; continues with the formation of a partnership between scientists and educators (through the use of a broker/facilitator if necessary) for the specific purpose of meeting that need; and leads to the development of educational materials which are then catalogued and distributed by an archiver/disseminator to a wide variety of users. A set of Implementation Principles governs the operations of the "Ecosystem" and also serves as a basis for making decisions concerning the types of education/outreach activities which OSS should sponsor and/or support. The Task Force identified a subset of its more than 50 individual Findings and Recommendations which require near-term actions in order to proceed with the development of the "Ecosystem". OSS intends to pursue the recommendations of the Task Force.

Technology development and transfer

The Office of Space Science Integrated Technology Strategy establishes the framework through which OSS will team with partners in NASA and industry to develop the critical technologies required to enhance space exploration, expand our knowledge of the universe, and ensure continued national scientific, technical and economic leadership.

The OSS vision of success for its Integrated Technology Strategy is the embodiment, at all levels and across all disciplines, of a continued commitment to develop, utilize and transfer technologies that provide scientific and globally competitive economic returns to the nation. To attain this vision, OSS strives to meet four primary goals: (1) OSS will identify and support the development of promising new technologies which will enable or enhance space science objectives and reduce mission life-cycle costs; (2) OSS will infuse these technologies into space science programs in a manner that is cost effective, with acceptable risk; (3) OSS will establish technology transfer as an inherent element of the space science project life cycle; and (4) OSS will support the development of strong and lasting implementing partnerships among industry, academia and government to assure the nation reaps maximum scientific and economic benefit from its Space Science program.

With its Integrated Technology Strategy, the Office of Space Science will contribute to both NASA crosscutting and Space Science mission-specific spacecraft technology advancements. This new role of ensuring crosscutting technology infusion will serve both internal and external customers. NASA's internal customers consist of the Human Exploration, Space Science, Mission to Planet Earth, and Aeronautics Enterprises. External customers include both the aerospace and non-aerospace industry, as well as other government agencies. Investments in spacecraft, science instrument, and ground or space-based systems technologies will ensure that new technologies continue to become available to enable innovative and cost-effective future missions. The crosscutting technology advancements will be achieved through a balance of near-term and far-term activities. Near-term (< 5-year) development will be targeted to specific user needs for currently planned missions, and far-term basic research (>5-year horizon) will identify and exploit major new scientific and technical discoveries to enable new missions.

MEASURES OF PERFORMANCE

The Office of Space Science has been working with the Office of Management and Budget, the NASA Advisory Committee, and NASA's Office of Policy and Plans to develop metrics in response to the Government Performance and Results Act (GPRA) of 1993. Although the following metrics are not the final set which will be used to address GPRA, they are indicative of the issues under consideration.

Fundamental Science

Fundamental Science is the primary objective of the Space Science program, however, it is also among the most difficult of outcomes to measure. OSS has developed two surrogate measures of fundamental scientific performance, each of which are based on assessments that are made independent of NASA. These metrics do not capture all aspects of performance that need to be measured, but they do provide important insights into fundamental scientific performance.

1) Science News metric - This metric is based on that journal's annual listing of "most important stories" going back 24 years (1973 - 1996). "Science News" tracks the new discoveries they consider most significant on an annual basis. By tallying the stories based on scientific or technical accomplishments each year, a metric is generated that can be used to compare OSS performance over time as compared to all other "world class" science in fields as diverse as archaeology and biomedicine. The following is a synopsis of our observations as of the end of 1996:

• Space Science discoveries have contributed 4.1% of world science return over the past 24-year period.
• A sharp spike in the mid-70s reflects the Viking mission to Mars in 1976. A second spike is seen in the late 1970s, led by Voyager's encounter with Jupiter. In contrast, the 1980's shows a steep decline, commensurate with the loss of Challenger which delayed the launch of new missions for several years.
• The late 1980s and early 1990s has seen a dramatic increase in science output, driven largely by the start of prime mission operations of major missions such as HST, the Cosmic Background Explorer (COBE) and Magellan
• 1994 was the best year on record for OSS, as Space Science discoveries contributed 9% of world science return, led by HST discoveries which produced over 5% of world scientific output. HST's output is the best performance for a single OSS program since Viking landed on Mars in the mid-70s. 1995 showed a slight decline, but was still well over the historical average. 1996 was another outstanding year, with Space Science accounting for 7% of world-wide discoveries. This output was led by the discovery of possible fossils of primitive life in a meteorite from Mars. HST also continues to make headlines, producing 3.5% of world discoveries in 1996 by itself, while the arrival of Galileo at Jupiter has led to the start of what is expected to be a succession of ground-breaking discoveries.

2) College Textbook metric - This metric attempts to show how the most significant topics of a single year get incorporated into the overall body of scientific knowledge. Six editions of a popular introductory college astronomy textbook spanning 1979-1995 were analyzed to assess OSS contributions. Long-term performance is measured by OSS's capture of "intellectual market share" (i.e. what percentage of the material is based on OSS contributions) as well as by overall growth of knowledge about astronomy.

• Textbook material based on Space Science contributions grows steadily, reflecting the cumulative effect of new information which is added to the overall body of scientific knowledge as new discoveries are added.
• The textbook grew 33% from 1979 to 1995, with the largest contributor being new chapters on Saturn, Uranus and Neptune, resulting from NASA deep space missions to the outer planets.
• In 1995, 27% of knowledge presented in the textbook was based on OSS contributions, which is double the 13% OSS contribution in 1979

Additional credibility accrues to these two metrics because of the significant correlation between the identification of new discoveries in "Science News" followed by their inclusion into college text 3-5 years later. An enclosed chart identifies the historical performance of OSS over the past 24 years in accordance with the two metrics just described.

Faster, Better, Cheaper

A major strategic thrust of OSS is to increase overall cost effectiveness of the Space Science Enterprise by providing more frequent access to space for the science community within an increasingly constrained budget environment. Current plans within the Space Science program call for a significant increase in the historical launch rate despite reduced resources. Toward this end, OSS has restructured several missions to reduce cost and schedule requirements. Mission series such as Explorers, Discovery, Mars Surveyor and New Millennium all emphasize the selection of future missions within predetermined cost, schedule and launch services requirements. The success of this new strategy is measured by three important criteria:

1) Development time - Mission development time is a key factor in putting fresh ideas into practice and in the overall cost of a mission, and, therefore, must be reduced from historical levels. OSS plans to reduce development times from an average of more than 9 years for missions launched in 1990-94 to less than four years for missions planned for launch in 2000-04.

• Future Explorers (i.e. MIDEX, UNEX and SMEX) are planned for 2-3 year development times vs 4-5 year development times of previous Delta-class missions.
• Discovery missions are planned for 3 year development schedules (or less)
• Mars Surveyor missions are planned for 3-4 year development schedules
• New Millennium missions are planned for 2-3 year development schedules
  

2) Development cost - Given the tightly constrained NASA budget plans for the next several years, mission development costs must be reduced, and cost estimate overruns must be eliminated if OSS is to sustain a reasonable launch rate for new missions. Consequently, NASA is now planning the majority of future missions to fit within a predetermined cost "cap" or target.

• Future Explorer missions are targeted at specific costs in FY 1994 dollars, all well below historical cost levels: Medium Explorers (MIDEX) ($70M); Small Explorers (SMEX) ($30-40M); University Explorers (UNEX) ($5M).
• The FUSE mission has been restructured from a $254 million Delta-class mission to a $100 million Med-Lite class mission, while the launch date has been accelerated by approximately two years.
  
• SIRTF, an FY 1998 new start, has been extensively restructured from its original configuration in order to reduce its development costs by a factor of 4 over the original estimate
• Discovery missions are constrained to no more than $150 million FY 1992 dollars for development, a fraction of what planetary missions have historically cost. The first four Discovery missions (Mars Pathfinder, NEAR, Lunar Prospector, and Stardust) are actually averaging less than $110 million FY 1992 dollars for development
• Mars Surveyor and New Millennium missions, while not strictly capped during the definition phase, are capped at the time of selection for development.
• Additional savings are achieved by constraining future mission designs to smaller, less expensive launch vehicles (i.e. Med-Lite, Small-class, Ultra-Lite) as opposed to Delta-class or higher as historically has been the case.

3) Launch rate - The provision of more frequent launch opportunities is essential to foster the next generation of space scientists and engineers, and to provide a more continuous flow of exciting new discoveries.

• MIDEX, SMEX and UNEX mission launches are anticipated at the rate of nearly 1 launch per year for each mission class, contingent upon available funding and the specific missions selected. We expect to significantly increase the UNEX launch rate around the beginning of the next decade, assuming availability of low-cost launchers
• Discovery and New Millennium missions each support an annual launch rate of 1 launch every 12-18 months
• The Mars Surveyor program supports 2 launches at every Mars launch opportunity (i.e. every 2 years)

A graph following this section illustrates the projected trend in declining mission cost and schedule requirements while accelerating the annual launch rate beyond FY 2000.

In addition to reductions in cost and schedule requirements for development and launch of spacecraft, OSS has sought cost effectiveness in mission operations and data analysis (MO&DA). This is the phase where the principal science objectives of every endeavor are accomplished. MO&DA is definitely becoming "better" and "cheaper", as illustrated by the average cost per year of operating missions. In 1994 the Office of Space Science operated 14 missions at an average cost of $20M per year per mission. Our current plans for FY 2002 include operation of 29 missions at an average cost of $6.3M per year per mission, a factor-of-3 improvement. (These figures exclude HST, AXAF and Cassini, large missions which would skew the data). MO&DA costs have been reduced by using smaller, "smarter" spacecraft, accepting more risk in mission operations, reducing funding to scientists after completion of the primary mission phase, and arranging for more international collaborations. A graph following this section illustrates the effects of these changes.

BASIS OF FY 1998 FUNDING REQUIREMENT (Thousands of Dollars)	FY 1996	FY 1997	FY 1998
Advanced x-ray astrophysics facility development	237,600	178,600	92,200

* Total cost information is provided in the Special Issues section

PROGRAM GOALS

The Advanced X-ray Astrophysics Facility (AXAF) is the third of NASA's Great Observatories, which include the Hubble Space Telescope and the Compton Gamma Ray Observatory. AXAF will observe matter at the extremes of temperature, density and energy content. Previous x-ray missions, such as the Small Astronomical Satellite-C and the Einstein Observatory have demonstrated that observations in the x-ray band provide a powerful probe into the physical conditions of a wide range of astrophysical systems. With its unprecedented capabilities in energy coverage, spatial resolution, spectral resolution and sensitivity, AXAF will provide unique and crucial information on the nature of objects ranging from nearby stars like our Sun to quasars at the edge of the observable universe. Some of the major scientific questions addressed by AXAF include:

• What is the age and size of the universe? AXAF will provide an independent measurement at x-ray wavelengths of the Hubble constant, which determines the answers to these questions. Brighter binary sources in galaxies within the Virgo cluster can be resolved and detected individually, as can sources in intermediate galaxies. Thus, the population of bright X-ray sources in hundreds of galaxies can be determined. Since high-energy X-rays are unaffected by obscuring material, the brightness of sources can be accurately measured and the hypothesis that these sources, or a subset of them, are "standard candles" can be accurately tested. If such "standard candles" are found, distances to nearby galaxies can be accurately determined. These distances are a crucial step in the derivation of the Hubble Constant and the potential of these measurements is truly exciting.
• What is dark matter? Dark matter accounts for more than 90% of the mass of the universe, but what it is remains a total mystery. The gravitational effects of dark matter have proven its existence, but it has yet to be identified. It may be massive amounts of ordinary matter in the form of small, non-radiating objects yet to be detected, or it may be some exotic new form of matter. AXAF will be able to map the distribution of dark matter in distant clusters of galaxies, contributing to our understanding of this enigma.
• What is the x-ray background radiation? Other x-ray missions have seen a faint x-ray background emission covering the entire sky, the nature of which is uncertain. AXAF is expected to detect quasars and active galaxies 100 times fainter than the Einstein Observatory could, and can thus look to significantly greater distances. This is unknown territory, except that the integrated emission from many unresolved faint sources probably contributes most of the X-ray background. Deep AXAF observations will come close to imaging this background and will provide a sample of distant objects which record the state of the universe at early times.
  

STRATEGY FOR ACHIEVING GOALS

The Marshall Space Flight Center (MSFC) was assigned responsibility for managing the AXAF Project in 1978 as a successor to the High Energy Astrophysics Observatory (HEAO) program. The scientific payload was selected through an Announcement of Opportunity (AO) in 1985 and confirmed for flight readiness in 1989. TRW was selected as prime spacecraft contractor for the mission, with major subcontracts to Hughes Danbury (mirror development), Eastman Kodak (High Resolution Mirror Assembly -- HRMA), and Ball Aerospace (Science Instrument Module - SIM). The Smithsonian Astrophysical Observatory (SAO) also has significant involvement throughout the program. AXAF will be launched on the Shuttle with an Inertial Upper Stage (IUS) provided by Boeing. International contributions are being made by the Netherlands (an instrument), Germany (an instrument), Italy (detector test facilities), and the United Kingdom (microchannel plates and science support).

AXAF was given new start approval in FY 1989, with full-scale development contingent upon demonstrating the challenging advances in mirror metrology and polishing technology. The first pair of mirrors were fabricated and tested in a specially designed X-ray Calibration Facility (XRCF) at MSFC in 1991, and the x-ray results validated the metrology and polishing. With the success of this Verification Engineering Test Article (VETA) #1 demonstration, the program proceeded fully into design and development.

The AXAF program was restructured in 1992 in response to downward revisions of the future funding projections for NASA programs. The original baseline was an observatory with six mirror pairs, a 15-year mission in low-Earth orbit, and shuttle servicing. The restructuring produced AXAF-I, an observatory with four mirror pairs to be launched into a high Earth orbit for a five year life time, and AXAF-S, a smaller observatory flying an X-Ray Spectrometer (XRS). A panel from the National Academy of Sciences (NAS) endorsed the restructured AXAF program. The FY 1994 AXAF budget was reduced by Congress, resulting in termination of the AXAF-S mission. The Committees further directed that residual FY 1994 AXAF-S funds be applied towards development of a similar instrument payload on the Japanese Astro-E mission to mitigate the science impact of losing AXAF-S. This activity is underway, and funding for Astro-E activities is requested within the Payload and Instrument Development line.

MEASURES OF PERFORMANCE

Performance Milestone	Plan	Actual/Revised	Description/Status
AXAF Observatory CDR	February 1996	February 1996	This major milestone was achieved on schedule. The review assessed the validity and maturity of observatory design as a functionally integrated system in terms of subsystem compatibility, interface requirements and ability to meet all established performance criteria within acceptable levels of technical, cost and schedule risk.
Science Instrument Module (SIM) completed	April 1996	June 1997	Fabrication of the Science Instrument Module completed at Ball Aerospace. The SIM will house the two focal plane science instruments on AXAF. Completion of this milestone is now scheduled for June 1997; a SIM surrogate was delivered to the XRCF in September 1996 to support calibration, with no impact to critical path slack
Deliver flight instruments	August 1996	January 1997 (HRC) & March 1997 (ACIS)	Flight instruments shipped upon completion of integration and test activities. An ACIS surrogate was delivered to the XRCF in September 1996 to support calibration, with no impact to critical path slack
X-ray calibration begins at MSFC	January 1997	--	Tests will verify HRMA mirror alignment and compare technical performance of mirrors and science instruments against predicted values. On schedule
Complete HRMA/Instrument calibration	April 1997	--	Verification of end-to-end optical performance. On schedule
Begin Observatory assembly and test	October 1997	--	Initiate integration of completed spacecraft with telescope and instruments at TRW, followed by full-up systems testing (thermal-vacuum, acoustic, etc.). On schedule
Deliver Observatory to KSC	June 1998	--	Observatory integration and systems testing completed at TRW. Begin integration with upper stage, final performance testing, and integration in Shuttle. On schedule.
Launch Observatory	August 1998	--	Shuttle deployment into low-Earth orbit followed by upper stage delivery to highly elliptical operational orbit. On schedule.

ACCOMPLISHMENTS AND PLANS

Detailed design activities for the spacecraft were completed on time in December 1995, and fabrication of the flight structure began in early 1996. The spacecraft Structural Test Article was completed in January 1996, and static testing was completed in April. The CDR for the entire AXAF Observatory was completed in February 1996.

A major milestone was achieved in November, with the completion of the integrated High Resolution Mirror Assembly (HRMA). After all mirrors were bonded into the HRMA, testing showed that it will meet all specifications for the accurate focusing of x-rays. The HRMA has been delivered to MSFC to support the start of calibration testing in January 1997.

As mentioned above, technical problems with the science instruments and the Science Instrument Module (SIM) have resulted in delays in the deliveries of flight models. A surrogate ACIS instrument and a surrogate SIM have been delivered to support XRCF testing; flight models will be delivered and integrated later. This adjustment to the schedule will allow the HRMA to be completely tested in the XRCF, without serious loss of critical path slack.

Following completion of XRCF testing in April, the HRMA will return to TRW for final integration with the flight instruments, the flight SIM, the transmission gratings, and other elements of the telescope assembly. Meanwhile, assembly and test of the spacecraft structure and support systems will continue through the end of the fiscal year. The telescope assembly and the spacecraft are scheduled for completion before the end of fiscal 1997, leading to the start of Observatory integration and testing in October. Observatory integration and testing will continue through June 1998, when the completed AXAF will be delivered to KSC for launch integration and then launch on the Shuttle in August.

Program costs are at or below planned levels, and reserves (as a percentage of work to go) are holding steady.

BASIS OF FY 1998 FUNDING REQUIREMENT (Thousands of Dollars)	FY 1996	FY 1997	FY 1998
SIRTF development	--	--	81,400

* Total cost information is provided in the Special Issues section

PROGRAM GOALS

The purpose of the Space Infrared Telescope Facility (SIRTF) mission is to explore the nature of the cosmos through the unique windows available in the infrared portion of the electromagnetic spectrum. These windows allow infrared observations to explore the cold Universe by looking at heat radiation from objects which are too cool to radiate at optical and ultraviolet wavelengths; to explore the hidden Universe by penetrating into dusty regions which are too opaque for exploration in the other spectral bands; and to explore the distant Universe by virtue of the cosmic expansion, which shifts the ultraviolet and visible radiation from distant sources into the infrared spectral region. To exploit these windows requires the full capability of a cryogenically-cooled telescope, limited in sensitivity only by the faint infrared glow of the interplanetary dust. SIRTF is the fourth of NASA's Great Observatories, which include the Hubble Space Telescope, the Compton Gamma Ray Telescope, and the Advanced X-Ray Astrophysics Facility. By completing NASA's family of Great Observatories, an infrared capability will enable the full power of modern instrumentation to be brought to bear, across the entire electromagnetic spectrum, on the central questions of modern astrophysics. Many of these questions can be unraveled only by the full physical picture that this broad spectral coverage uniquely provides.

Rather than simply "descoping" the original Titan-class SIRTF -- the original "Great Observatory" concept -- to fit within a $400 million (FY94) cost ceiling imposed by NASA, scientists and engineers have instead redesigned SIRTF from the bottom-up. The goal was to substantially reduce costs associated with every element of SIRTF -- the telescope, instruments, spacecraft, ground system, mission operations, and project management. With an eye towards cost, and in recognition of the unprecedented sensitivity afforded by the latest arrays, the SIRTF Science Working Group identified a handful of the most compelling problems in modern astrophysics for which SIRTF could make unique and important contributions. These primary science themes, which have recently received the endorsement of the National Research Council's Committee on Astronomy and Astrophysics, satisfy most of the major scientific themes outlined for the original SIRTF mission in the Bahcall Report (which judged SIRTF the highest priority major new program for all of U.S. astronomy in the 1990s). The focus of SIRTF's impressive scientific capabilities will be on:

• Protoplanetary and Planetary Debris Disks. One of the most exciting and unexpected discoveries of the Infrared Astronomical Satellite (IRAS) survey was that many nearby stars are surrounded by disks of material like the dust in our own Solar System. Modeling of the IRAS data suggests that these disks contain particles ranging in size from ~1 mm up to bodies as large as asteroids and comets, with some arguments suggestive of still larger, planet-sized objects. Further exploration of this phenomenon will help us understand the frequency and properties of planetary systems around nearby stars. SIRTF is expected to contribute significantly to this exploration by imaging the nearby examples in great detail, searching for possible empty inner regions caused by planets. SIRTF's ability to study debris disks around literally thousands of stars should allow the relations between planetary debris disk properties and stellar mass, luminosity, age, and multiplicity to be determined, revealing fundamentals of planetary system formation.
• Brown Dwarfs and Super Planets. Brown dwarfs are objects with masses between 0.001 and 0.08 that of the Sun (0.001 - 0.08 M[sun]). They are too low in mass to sustain nuclear burning but may be visible in the infrared as they radiate the gravitational energy released in their formation. They are of particular interest because they may account for some of the "missing mass" which forms a dynamically significant, but as yet unseen, halo for our Galaxy -- and other galaxies as well. As brown dwarfs age, they become cooler and fainter in the infrared. However, in a single 600-second integration at the 4.5-micron wavelength, SIRTF is designed to detect 0.03 M[sun] objects with ages of 10 billion years -- as is appropriate for the halo of our Galaxy - at distances up to about 100 light-years from the sun. If the missing mass in our galaxy is in the form of 0.03 solar mass brown dwarfs, approximately 1000 of them should be present in the data base created by a SIRTF survey which will cover about 1% of the sky.
• Ultraluminous Galaxies and Active Galactic Nuclei. IRAS identified several new classes of infrared-luminous galaxies. One such class which was found in the main IRAS catalogs is the ultraluminous galaxies (ULGs), which have optical images suggestive of violent interactions and mergers, and luminosities well into the luminosity range of quasars. More recently, several even more luminous galaxies have been found through followup studies of the IRAS Faint Source Catalog and Database. These Active Galactic Nuclei (AGNs) radiate 90 to >99% of their total luminosity at infrared wavelengths. SIRTF is designed to detect ULGs billions of light-years away and study their evolution in space-time. If ULGs are triggered by galaxy interactions, there should be more of them at earlier epochs, when the higher density of the universe would have led to more frequent galaxy-to-galaxy interactions. The same observations would detect AGN objects near the edge of the observable universe and determine whether they are different -- perhaps powered by a different physical mechanism -- than the lower luminosity ULGs. SIRTF should be able to determine the physical conditions in the interiors of these objects, thereby determining the source of their luminosity.
• The Early Universe -- Deep Surveys. SIRTF's deep imaging at wavelengths between 3 and 8 microns is designed to probe the early universe. These measurements will permit a determination of redshift, the speed at which distant objects are receding from us. Comparison of SIRTF's census of galaxy quantities and properties as a function of redshift will test our understanding both of the evolution of galaxies and of the geometry of space-time. The investigations of the most luminous infrared galaxies discussed earlier will provide additional insights into the early universe. It has been suggested that these objects may be protogalaxies -- undergoing an initial cataclysmic burst of star formation -- because their luminosity is far too high to be sustained by nuclear burning in a normal stellar population. If this conjecture is true, the numbers of such objects ought to increase markedly with look-back time, and SIRTF's ability to detect them ought to reveal many new examples.

While these topics drive the mission design, SIRTF's powerful capabilities have the potential to address a wide range of other astronomical investigations, including studies of the outer solar system, the early stages of star formation, and the origin of chemical elements. Taken together, SIRTF's design capabilities are expected to allow it to achieve many of the initial goals of the Origins program, which are outlined in the Space Science summary section. Moreover, SIRTF's measurements of the density and opaqueness of the dust disks around nearby planets will help set the requirements for future Origins missions designed to directly detect planets.

STRATEGY FOR ACHIEVING GOALS

The FY 1998 budget proposes appropriation language for multi-year funding of SIRTF development and launch costs. The requested appropriations are $81.4 million for FY 1998, $134.5 million for FY 1999, $130.0 million for FY 2000, $117.3 million for FY 2001 and $25.8 million for FY 2002, for a total of $489.0 million. Enactment of these appropriations will ensure the stability to manage and execute this program within its budget and schedule commitments.

The Jet Propulsion Laboratory (JPL) was assigned responsibility for managing the SIRTF project. The SIRTF Mission is composed of six major system elements and components as described below. The first three elements (the Science Instruments, Cryo/Telescope Assembly, and Spacecraft Assembly) will be assembled into a single space-based observatory system by means of the fourth element -- System Integration and Test. The fifth element is the launch vehicle, and the sixth is the ground system which will be used to operate the Observatory on the ground prior to launch, and in space to achieve the mission objectives.

Science Instruments will be provided by three Principal Investigators (PIs) selected by NASA in 1984 in response to a NASA Announcement of Opportunity. The three science instruments and their PIs are: the Infrared Array Camera (IRAC), Smithsonian Astrophysical Observatory, Dr. Giovanni Fazio; the Infrared Spectrometer (IRS), Cornell University, Dr. James Houck; and the Multiband Imaging Photometer for SIRTF (MIPS), University of Arizona, Dr. George Rieke.

The Cryo/Telescope Assembly (CTA) will be developed by Ball Aerospace and Technologies Corporation, Boulder, CO, as an industrial member of the SIRTF Integrated Project Team, and will consist of all of the elements of SIRTF that will operate in space at reduced or cryogenic temperatures. This will include the telescope, telescope cover, cryostat, and supporting structures and baffles. The cryostat will contain the cold portions of the PI-supplied Science Instruments.

The Spacecraft Assembly will be developed by Lockheed Martin Missiles and Space, Sunnyvale, CA, as an Industrial member of the SIRTF Integrated Project Team, and will consist of all of the elements of SIRTF that are needed for power, data collection, Observatory control and pointing, and communications. These elements of SIRTF are nominally operated at or near 300 degrees K, and will also include the warm portions of the PI-provided Science Instruments.

System Integration and Test (SIT) has been identified as a separate system element, and will be provided by Lockheed Martin Missiles and Space, Sunnyvale, CA, as an Industrial member of the SIRTF Integrated Project Team. This element will complete the assembly of the Observatory using the SIs, the CTA, and the Spacecraft Assembly. System level verification and testing, launch preparations and launch of SIRTF will be performed by this element.

Ground and Operations System development will be accomplished in parallel with Observatory development. This will be done to reduce redundant development of ground equipment and to assure compatibility between ground equipment and the Observatory after launch. This equipment will be developed by the mission development team at JPL.

SIRTF is planned for launch on a Delta launch vehicle during FY 2002.

MEASURES OF PERFORMANCE

Performance Milestone	Plan	Actual/Revised	Description/Status
Non Advocate Review (NAR)	October 1997	--	The review will demonstrate that SIRTF has a plan for the design and development that is credible and consistent with NASA resources and science community expectations.
Preliminary Design Review	October 1997	--	Review at the completion of the functional design of SIRTF to demonstrate that the project is technically ready to proceed with detail design (Phase C).
Start Phase C/D	April 1998	--	Approval by NASA to proceed with the design and development of the SIRTF project
Critical Design Review	October 1998	--	The review at the completion of the detail design will demonstrate that the SIRTF design is credible within planned resources, and that it satisfies the science community's expectations.
Launch	December 2001	--	Launch on a Delta launch vehicle to a solar orbit trailing the Earth.

ACCOMPLISHMENTS AND PLANS

Please refer to the Supporting Research and Technology section for a discussion of FY 1996 - 1997 accomplishments during SIRTF Phase A and Phase B studies. With the funds requested for FY 1998, SIRTF will be able to enter Phase C/D. A Preliminary Design review is planned for October 1997 and a Critical Design Review is planned for October 1998.

BASIS OF FY 1998 FUNDING REQUIREMENT (Thousands of Dollars)	FY 1996	FY 1997	FY 1998
Relativity mission development	51,500	59,600	45,600

* Total cost information is provided in the Special Issues section

PROGRAM GOALS

The purpose of the Relativity Mission (also known as Gravity Probe-B) is to verify Einstein's theory of general relativity. This is the most accepted theory of gravitation and of the large-scale structure of the Universe. General relativity is a cornerstone of our understanding of the physical world, and consequently of our interpretation of observed phenomena. However, it has only been tested in a limited number of ways. An experiment is needed to explore more precisely the predictions of the theory in two areas: (1) a measurement of the "dragging of space" by rotating matter; and (2) a measurement of space-time curvature known as the "geodetic effect". The dragging of space has never been measured, and the geodetic effect needs to be measured more precisely. Whether the experiment confirms or contradicts Einstein's theory, its results will be of the highest scientific importance. The measurements of both the frame dragging and geodetic effects will allow Einstein's Theory to be either rejected or given greater credence. The effect of invalidating Einstein's theory would be profound, and would call for major revisions of our concepts of physics and cosmology.

In addition, the Relativity Mission is contributing to the development of cutting-edge space technologies that are also applicable to future space science missions and transportation systems.

STRATEGY FOR ACHIEVING GOALS

This test of the general theory requires advanced applications in superconductivity, magnetic shielding, precision manufacturing, spacecraft control mechanisms, and cryogenics. The Relativity Mission spacecraft will employ super-precise quartz gyroscopes (small quartz spheres machined to an atomic level of smoothness) coated with a super-thin film of superconducting material (needed to be able to "read-out" changes in the direction of spin of the gyros). The gyros will be encased in an ultra-low magnetic-shielded, supercooled environment (requiring a complex process of lead-shielding, a Dewar containing supercooled helium, and a sophisticated interface among the instrument's telescope, the shielded instrument probe, and the Dewar). The system will maintain a level of instantaneous pointing accuracy of 20 milliarcseconds (requiring precise star-tracking, a "drag free" spacecraft control system, and micro-precision thrusters). The combination of these technologies will enable the Relativity Mission to measure: (1) the distortion caused by the movement of the Earth's gravitational field as the Earth rotates west to east; and, (2) the distortion caused by the movement of the Relativity Mission spacecraft through the Earth's gravitational field south to north, to a level of precision of 0.2 milliarcsecond per year (the width of a human hair observed from 50 miles).

The expertise to design, build and test the Relativity Mission, as well as the detailed understanding of the requirements for the Dewar and spacecraft, resides at Stanford University in Palo Alto, CA. Consequently, MSFC has assigned responsibility for experiment management, design, and hardware performance to Stanford. Science experiment hardware development (probe, gyros, dewar, etc.) is conducted at Stanford in collaboration with Lockheed/Palo Alto Research Laboratory (LPARL). Spacecraft development and systems integration will be performed by Lockheed Missiles and Space Corporation (LMSC). Launch is scheduled for October 2000 aboard a Delta II launch vehicle.

MEASURES OF PERFORMANCE

Performance Milestone	Plan	Actual/Revised	Description/Status
Flight Model Dewar Delivery	November 1996	October 1996	Delivery of the largest Helium Dewar ever made for a science mission. Ready for integration with the Probe B prototype for the second series of performance tests. Completed ahead of schedule
Ground Tests-2A start	June 1997	--	Conduct the third series of performance tests using the flight model dewar and Probe B prototype. Expected to be accomplished early.
Flight Probe Delivery	September 1997	--	Supports start of Science Mission payload (dewar, probe, and telescope) integration and testing in early FY 1998. Expected to be completed early.
Flight Probe integrated with Science Instrument Assembly	April 1998	--	Successful interface of the dewar to the science payload. Expected to be completed early.
Launch	October 2000	--	Launch aboard a Delta II launch vehicle. Program ahead of schedule to achieve this launch date.

ACCOMPLISHMENTS AND PLANS

The program continues ahead of the baseline schedule to launch the Relativity Mission by October 2000. The flight dewar was completed ahead of schedule and advances have been made in the scientific payload design. The second series of ground tests (GTU-1A) demonstrated the proper functioning of many aspects of the design. The third series of ground tests (GTU-2A), which are scheduled to start in June 1997, will incorporate the flight dewar and will transition later (following the delivery of the flight probe, which interfaces the science payload to the dewar) into the final series of ground tests.

The spacecraft development has also made outstanding progress. The PDR was held seven months ahead of schedule, and the spacecraft's unique thrusters and its balancing mechanisms have passed several qualification tests. The spacecraft CDR (planned for October 1997) is also likely to be accomplished significantly ahead of schedule.

An External Independent Readiness Review (EIRR) team is currently being formed to ensure that the mission will meet all established Level 1 technical and scientific requirements.

BASIS OF FY 1998 FUNDING REQUIREMENT (Thousands of Dollars)	FY 1996	FY 1997	FY 1998
Cassini Development	191,500	89,600	9,000

* Total cost information is provided in the Special Issues section

PROGRAM GOALS

Building on the discoveries made by the Pioneer and Voyager missions, the Cassini program will provide unprecedented information on the origin and evolution of our solar system. It will help tell how the necessary building blocks for the chemical evolution of life are formed elsewhere in the universe. The Cassini mission will conduct a detailed exploration of the Saturnian system including: 1) the study of Saturn's atmosphere, rings and magnetosphere; 2) remote and in situ study of Saturn's largest moon, Titan; 3) the study of Saturn's other icy moons; and 4) a Jupiter flyby to expand our knowledge of the Jovian System. In conjunction with Galileo's study of the Jovian system, the mission should also provide much insight as to how and why the large, gaseous outer planets have evolved much differently than the inner solar system bodies.

STRATEGY FOR ACHIEVING GOALS

Cassini is scheduled for launch in October 1997 aboard a Titan IV launch vehicle. An extensive cruise period is required to reach Saturn, during which the spacecraft will fly by Venus, Earth, and Jupiter to gain sufficient velocity to reach its destination. Upon arrival in June 2004, the spacecraft will begin four years of study of the Saturnian system that will provide intensive, long-term observations of Saturn's atmosphere, rings, magnetic field, and moons. In conjunction with the observations conducted by the spacecraft, the European Space Agency (ESA) - provided Huygens Probe will be injected into the atmosphere of Saturn's moon Titan. The probe will conduct in-situ physical and chemical analyses of Titan's methane-rich, nitrogen atmosphere, that is a possible model for the pre-biotic stage of the Earth's atmosphere. The Cassini spacecraft will also obtain a radar map of most of Titan's surface.

The Jet Propulsion Laboratory (JPL) has been assigned responsibility for managing the Cassini Project and for developing the spacecraft. NASA also has four partners in the Cassini project: the Department of Defense/Air Force is constructing a Titan IV Centaur launch vehicle; the Department of Energy is contributing the Radioisotope Heater Units (RHUs) and Radioisotope Thermoelectric Generators (RTGs) for the mission; the European Space Agency (ESA) is providing the Huygens probe; the Italian Space Agency (ASI) is contributing the High Gain/Low Gain Antenna for the spacecraft and elements of the radar mapper.

MEASURES OF PERFORMANCE

Performance Milestone	Plan	Actual/Revised	Description/Status
Start System Level Tests	May 1996	May 1996	Integration, test and checkout of flight hardware and instruments
Deliver Flight Model Science Instruments	July 1996	July 1996	Delivery of flight model instruments to JPL for integration with the spacecraft.
Start Spacecraft Environmental Tests	October 1996	October 1996	Tests entire spacecraft performance in a simulated mission environment to assure proper operation in space
Ship spacecraft to KSC	April 1997	--	Complete system level integration and test activities. Begin integration with Titan IV/Centaur launch vehicle at Kennedy Space Center (KSC). On schedule
Spacecraft launch	October 1997	--	Development phase complete. Initiate spacecraft checkout and cruise operations. On schedule.

ACCOMPLISHMENTS AND PLANS

Cassini spacecraft flight system integration continued through the first half of FY 1996. Engineering model instruments were delivered in mid-FY 1996 for integration and test with the spacecraft systems. Flight model instruments were delivered in late calendar FY 1996 for integration with the spacecraft in preparation for spacecraft environmental tests. ESA also delivered the Engineering Model Huygens Probe in early FY 1996 for integration and test with the spacecraft, and Italy delivered the protoflight High Gain Antenna.

For FY 1997 Cassini funding will support completion of the flight model science instruments, and remaining integration, environmental, and system test activities that are required prior to shipment of the spacecraft to KSC. The spacecraft will be delivered to KSC in April 1997. The RTG's will also be completed and shipped to KSC by the Department of Energy in April, and will be integrated to the spacecraft in July. Ground System software development and testing will be completed in July, and training of the flight operations team will be completed. The Launch Readiness Review and the President's launch decision will be completed in September for an October 1997 launch.

Cassini will be launched in October 1997 aboard a Titan IV/Centaur launch vehicle, and is targeted for its first flyby of Venus in April 1998 for a gravitational assist as it begins its seven-year cruise to Saturn.

BASIS OF FY 1998 FUNDING REQUIREMENT (Thousands of Dollars)	FY 1996	FY 1997	FY 1998
TIMED Development	--	18,200	48,200

* Total cost information is provided in the Special Issues section

PROGRAM GOALS

The primary objective of the TIMED mission is to investigate the energetics of the Mesosphere and Lower Thermosphere/ Ionosphere (MLTI) region of the Earth's atmosphere (60-180 km altitude). The MLTI is a region of transition in which many important processes change dramatically. It is a region where energetic solar radiation is absorbed, energy input from the aurora maximizes, intense electrical currents flow, and atmospheric waves and tides occur; and yet, this region has never been the subject of a comprehensive, long-term, global investigation. TIMED will provide a core subset of measurements defining the basic states (density, pressure, temperature, winds) of the MLTI region and its thermal balance for the first time. These measurements will be important for developing an understanding of the basic processes involved in the energy distribution of this region and the impact of natural and anthropogenic variations. In a society increasingly dependent upon satellite technology and communications, it is vital to understand the atmospheric variabilities so that the impact of these changes on tracking, spacecraft lifetimes, degradation of materials, and re-entry of piloted vehicles can be predicted. The mesosphere may also show evidence of anthropogenic effects that could herald global-scale environmental changes. TIMED will characterize this region to establish a baseline for future investigations of global change.

STRATEGY FOR ACHIEVING GOALS

The TIMED mission is the first science mission in the Solar Terrestrial Probes (STP) Program, as detailed in Space Science Strategic Plan. TIMED is part of NASA's initiative aimed at providing cost-efficient scientific investigation and more frequent access to space. The TIMED mission is scheduled aggressively, but realistically, for a three year development program, cost-capped at $100 million in FY 1994 dollars. TIMED will be developed for NASA by the John Hopkins University Applied Physics Laboratory (APL). The Aerospace Corporation, the University of Michigan, NASA's Langley Research Center with the Utah State University's Space Dynamics Laboratory, and the National Center for Atmospheric Research will provide instruments for the TIMED mission.

TIMED is scheduled for launch in January 2000 aboard a Med-Lite Class launch vehicle. TIMED will begin its 36-month Phase C/D development period in April 1997. TIMED will be a single spacecraft located in a high-inclination, low-Earth orbit with instrumentation to remotely sense the mesosphere/lower thermosphere/ionosphere regions of the Earth's atmosphere. TIMED will carry four instruments: Solar Extreme ultraviolet Experiment (SEE), Infrared Sounder (SABER), Ultraviolet Imager (GUVI), and Doppler Interferometer (TIDI).

MEASURES OF PERFORMANCE

Performance Milestone	Plan	Actual/Revised	Description/Status
Complete Phase B; start C/D	April 1997	--	Complete definition study and initiate the 36-month development effort. On schedule.
Non-Advocate Review	February 1997	--	Conduct Design Concurrence and Cost Review.
Preliminary Design Review	February 1997	--	Confirm that the science goals and objectives are achievable within Mission Design
Critical Design Review	January 1998	--	Confirmation that the design is sufficient to move into full-scale development.
Completion of Instrument Development	December 1998	--	Complete delivery of all 4 flight instruments to APL.
Begin Spacecraft I&T	January 1999	--	Spacecraft integration and test in preparation for launch.
Launch	January 2000	--	Launch aboard a Med-Lite Launch vehicle

ACCOMPLISHMENTS AND PLANS

The TIMED mission was initiated in 1994, and completed requirements definition and conceptual design in 1994. Risk reduction efforts were completed in 1995 to ensure that the mission objectives and science goals are achievable within budget. A definition study (Phase B) for the TIMED mission continued throughout FY 1996, and is scheduled for completion in mid-FY 1997.

A contract for the TIMED development will be awarded in the third quarter of FY 1997 to enable full-scale development of the four instruments and the spacecraft. A Preliminary Design Review (PDR) will be held in first quarter of 1997, with a Critical Design Review (CDR) in the first quarter of 1998. Long-lead procurements will be initiated in FY 1997 to allow APL to meet its target launch readiness date, January 2000. Instrument and spacecraft subsystem fabrication will take place in FY 1998, and instrument and subsystem integration and test will begin in early FY 1999. TIMED will be launched aboard a Med-Lite class launch vehicle.

BASIS OF FY 1998 FUNDING REQUIREMENT (Thousands of Dollars)	FY 1996	FY 1997	FY 1998
Tethered satellite system	4,200	--	--
Astro-E	7,400	5,600	7,100
Mars instruments	2,600	--	--
Shuttle/international payloads	11,700	11,300	5,200
Total	25,900	16,900	12,300

PROGRAM GOALS

Payload and Instrument Development supports a number of instruments and payloads to be used on international satellites or on Spacelab missions. International collaborative programs offer opportunities to leverage U.S. investments, obtaining scientific data at a relatively low cost. Spacelab missions utilize the unique capabilities of the Shuttle to perform scientific experiments that do not require the extended operations provided by free-flying spacecraft. The Payload and Instrument Development program supports investigations in Sun-Earth connections, the structure and evolution of the universe, and exploration of the solar system.

STRATEGY FOR ACHIEVING GOALS

The Tethered Satellite System (TSS) program is an international cooperative project with the Italian government. The TSS was flown aboard the shuttle in July-August 1992, and reflown in February 1996, to perform space plasma experiments while also investigating the dynamic forces acting upon a tethered satellite.

In the FY 1994 appropriation, Congress directed NASA to pursue flight of a GSFC-developed X-ray spectrometer on the Japanese Astro-E mission. NASA will contribute improved foil mirrors and an x-ray calorimeter derived from the spectrometer previously planned for the canceled AXAF-S mission. This new device will measure the energy of an incoming X-ray photon by precisely measuring the increase in temperature of the detector as the photon is absorbed. It will provide high quantum efficiency over a large instantaneous bandpass, from 0.3 to 10 keV, at an unprecedented spectral resolution of approximately 15 eV over the entire bandpass. The foil mirrors will have a large collecting area, approximately 400 square centimeters at 6 keV, and will provide approximately 2 arc second resolution. These capabilities will permit an unprecedented sensitivity study of a wide range of astrophysical sources, answer many outstanding questions in astrophysics, and likely pose many new ones.

The Jet Propulsion Laboratory (JPL) provided two Mars Oxidation (MOx) experiments for Russia's Mars '96 mission, which launched unsuccessfully in November 1996.

The Payload and Instrument Development program also supports several other international and U.S. development projects. These include the Orbiting and Retrievable Far and Extreme Ultraviolet Spectrometer (ORFEUS) and Interstellar Medium Absorption Profile Spectrograph (IMAPS), to be flown on the German-U. S. Shuttle Pallet Satellite (SPAS); the Satelite de Aplicaciones Cientificas-B (SAC-B), the first Argentinean spacecraft; the High Energy Transient Experiment (HETE, 1996), a small satellite for study of gamma-ray burst phenomena in multiple wavelengths; ground-based support for Japan's Very Long Baseline Interferometry Space Observatory Program (VSOP, 1997) and Russia's RADIOASTRON (1999) program; portions of two instruments to be flown on Europe's X-ray Mirror Mission (XMM, 1999); and participation in Europe's International Gamma Ray Astrophysics Laboratory (INTEGRAL, 2001).

ORFEUS/IMAPS, which flew aboard the Shuttle in the summer of 1993 and was reflown in November 1996, has explored the character of extreme and far ultraviolet sources, studied the composition and distribution of matter in the neighborhood of the Sun, and performed direct observations of the interstellar medium.

SAC-B and HETE were launched unsuccessfully on a single Pegasus rocket in November 1996. The spacecraft achieved orbit, but the Pegasus failed to release the two satellites due to a power failure on the third stage. SAC-B was a collaborative program with the Argentines. Although primarily an engineering test of the first flight of an Argentine satellite, the mission was to use an Argentine instrument to observe hard x-rays from solar flares and use a U.S. instrument to survey diffuse x-ray emissions over a major portion of the sky. The Argentines achieved many of their engineering objectives and do not intend to build a replacement. HETE was a collaborative program with France and Japan managed by the Massachusetts Institute of Technology. The mission was to provide information about the precise location of gamma-ray bursters and spectral analysis of these and other high energy transient phenomena. NASA is currently considering a potential HETE recovery mission, which would use existing designs and hardware.

The Space Very Long Baseline Interferometry (SVLBI) program is composed of the Japanese VSOP and Russian Radioastron missions. These two international missions will provide the highest resolution images of radio sources ever obtained. NASA is participating on the science advisory groups and providing ground processing hardware, tracking support, and the construction of four ground science stations to support both missions. With its extremely long baseline, VSOP and Radioastron will explore very small radio sources with high angular resolution, thereby achieving higher resolution of active galactic nuclei and compact radio sources than can be achieved on the ground. VSOP and Radioastron each have a design life of 3 years.

The ESA XMM satellite will have highly sensitive instruments providing broad-band study of the x-ray spectrum. This mission will combine telescopes with grazing incidence mirrors and a focal length greater than 7.5 meters with three imaging array instruments and two Reflection Grating Spectrometers (RGS). The U.S. is providing components to the Optical Monitor (OM) and RGS instruments. XMM science will be complementary to the U.S. Advanced X-ray Astrophysics Facility (AXAF). XMM's higher through-put (i.e., higher number of photons collected) will allow somewhat better spectroscopy of faint sources, while AXAF will excel at high resolution imaging. XMM has a lifetime goal of 10 years.

The ESA INTEGRAL mission will perform detailed follow-on spectroscopic and imaging studies of objects initially explored by the Compton Gamma Ray Observatory. Its enhanced spectral resolution and spatial resolution in the nuclear line region will provide a unique channel for the investigation of processes -- nuclear transitions, e-/e+ annihilation, and cyclotron emission/absorption -- taking place under extreme conditions of density, temperature, and magnetic field. U.S. participation consists of co-investigators providing hardware and software components to the spectrometer and imager instruments; a co-investigator for the data center; a mission scientist; and a provision for ground tracking and data collection. Launch is expected in 2001; INTEGRAL has a design life of two years.

MEASURES OF PERFORMANCE

Tethered Satellite System:

Performance Milestone	Plan	Actual/Revised	Description/Status
TSS launch	February 1996	February 1996	Operations conducted aboard Shuttle mission STS 75.

Astro-E:

Performance Milestone	Plan	Actual/Revised	Description/Status
Engineering model spectrometer delivery	April 1996	April - October 1996	With the delivery of this unit, the construction and test procedures needed for the flight unit have been validated. The unit provided to the Japanese served to test system interfaces and allow complete systems tests to be run.
First engineering mirror delivered to Japan	October 1996	November 1996	With the delivery of the first mirror, the construction, assembly and test procedures have been completely demonstrated. Subsequent development of the next four mirrors will follow a known path. The Japanese will be able to test out system interfaces, conduct environmental tests, and conduct complete systems tests.
Flight model spectrometer delivery to Japan	July 1997	December 1997-May 1998	This task concludes the XRS instrument construction phase and begins a period of validation, testing and calibration prior to delivery of the instrument to Japan in 1998. Expected to be completed late, with subcomponents delivered to Japan as completed, but still supports the Japanese schedule.

Mars Instruments:

Performance Milestone	Plan	Actual/Revised	Description/Status
Deliver MOx Sensor Head	May 1996	May 1996	Provide two refurbished MOx sensor heads to Russia for spacecraft integration
Spacecraft launch	November 1996	November 1996	Launched on Russian Proton booster; failed

Other Shuttle/International:

Performance Milestone	Plan	Actual/Revised	Description/Status
SAC-B/HETE launch	November 1995	November 1996	Delayed pending Pegasus launch vehicle recovery. Launch failure in November 1996.
Cluster launch	November 1995	June 1996	Delayed by ESA until May 1996 due to Ariane-V launch vehicle problems. Launch failure in June 1996.
VSOP launch	September 1996		Instrument/spacecraft integration and test completed: Japanese launch.

ACCOMPLISHMENTS AND PLANS

Despite loss of the Italian satellite during deployment in February 1996, the TSS payload did obtain some useful data. Data analysis activities will completed in the near future.

Delivery of the engineering model Astro-E calorimeter was performed in pieces, and completed in time to support the Japanese schedule requirements. Fabrication of the flight model has begun. Verification and environmental tests will be completed in early FY 1998. Design work for the five mirrors which will be supplied to the Astro-E mission has been completed by the GSFC Mirror team, and fabrication has begun. Delivery of the first engineering model mirror to the Japanese occurred in November 1996. Delivery of the first flight mirror to the Japanese is scheduled for August 1997, and the fifth and final mirror will be delivered by December 1998. The project is on schedule for a February 2000 launch.

The First Announcement of Opportunity (AO) for international competition for observing time on the SVLBI program was released in June 1995. Initial VSOP science operations are scheduled to begin May 1997, following launch in January. XMM flight model components are to be shipped by June 1997 in support of a launch in December 1999.

BASIS OF FY 1998 FUNDING REQUIREMENT (Thousands of Dollars)	FY 1996	FY 1997	FY 1998
Advanced Composition Explorer	18,500	18,700	5,500
Far Ultraviolet Spectroscopic Explorer	56,600	22,000	26,800
Medium Explorers	13,700	41,200	62,400
Small Explorers	33,700	35,000	37,800
University Class Explorers	3,000	2,400	4,200
Explorer Planning	6,700	5,700	6,000
*Total	132,200	125,000	142,700

* Total cost information is provided in the Special Issues section

PROGRAM GOALS

The goal of the Explorer program is to provide frequent, low-cost access to space for Physics and Astronomy investigations that can be accommodated with small to mid-sized spacecraft. The program supports investigations in all space physics and astrophysics disciplines. Investigations selected for Explorer projects are usually of a survey nature, or have specific objectives not requiring the capabilities of a major observatory. The Explorer program continues to seek reductions in the cost of developing spacecraft, in order to provide more frequent launch opportunities for space science missions.

STRATEGY FOR ACHIEVING GOALS

Explorer mission development is managed within an essentially level funding profile. New mission starts are therefore subject to availability of sufficient funding in order to stay within the total program budget. Explorer missions are categorized by size, starting with the largest, Delta-class, moving down through the Medium-class (MIDEX), the Small-class (SMEX) and the University-class (UNEX) missions. As part of NASA's efforts to reduce the cost of Explorer missions, no new Delta-class missions are budgeted. NASA also funds a technology development program within the Explorer program, with the goal of reducing the weight and cost of future small spacecraft. Funding for Explorer mission studies is also provided within the Explorers budget.

Delta Class

The final Delta-class mission still in development, the Advanced Composition Explorer (ACE), was initiated in November 1993, and is scheduled for launch no later than December 1997. This space physics mission will use nine instruments to study the composition of the solar corona, interplanetary and interstellar media, and galactic matter across a wide range of plasma phenomena. The instruments include six high-resolution spectrometers, designed to have better collecting power than previous systems, to study the mass and charge of plasma phenomena. Three other instruments will provide measures of the lower energy phenomena related to the solar wind. Spacecraft development of ACE is provided by the Johns Hopkins University Applied Physics Laboratory, with project management by GSFC. Foreign participation on ACE includes the University of Bern which will provide instrument components, and the Max Planck Institute which will provide a flight data system shared by three instruments.

Medium Class

The new Medium-class Explorer (MIDEX) program was initiated to facilitate more frequent flights, and thus more research opportunities, in the areas of astrophysics and space physics. Plans call for about one MIDEX mission to be launched per year, with development cost capped at no more than $70 million (FY 1994 dollars) each, excluding the costs of the launch vehicle and mission operations and data analysis. In March 1996 NASA selected the first two science missions for the new MIDEX program. The two missions selected for definition studies leading to confirmation and development are the Microwave Anisotrophy Probe (MAP) and the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE). The MAP mission will undertake a detailed investigation of the cosmic microwave background to help understand the large-scale structure of the universe, in which galaxies and clusters of galaxies create enormous walls and voids in the cosmos. GSFC will be developing the MAP instruments in cooperation with Princeton University. The IMAGE mission will use three-dimensional imaging techniques to study the global response of the Earth's magnetosphere to variations in the solar wind, the steam of electrified particles flowing out from the Sun. The magnetosphere is the region surrounding the Earth controlled by its magnetic field and containing the Van Allen radiation belts and other energetic charged particles. Southwest Research Institute has been selected to develop the IMAGE mission.

Development of the Far Ultraviolet Spectroscopy Explorer (FUSE) began early in FY 1996. The FUSE mission, previously planned as a Delta-class mission, was restructured in order to reduce costs and accelerate the launch date from CY 2000 to late CY 1998. Although not a MIDEX mission, FUSE can be seen as a transitional step towards the MIDEX program. FUSE will conduct high resolution spectroscopy in the far ultraviolet region. Major participants include the Johns Hopkins University, the University of Colorado, and University of California, Berkeley; Orbital Sciences Corporation has been selected by JHU as the spacecraft developer. Canada will provide the fine error sensor assembly, and France will provide holographic gratings. GSFC will provide management oversight of this Principal Investigator-managed mission.

Small Class

Small Explorers (SMEX) include the Fast Auroral Snapshot (FAST), the Submillimeter Wave Astronomy Satellite (SWAS), the Transition Region and Coronal Explorer (TRACE) and the Wide-field Infrared Explorer (WIRE) missions. These missions will launch aboard Pegasus launch vehicles. These SMEX missions are managed by GSFC, where the spacecraft are developed in-house. SMEX missions are capped at $35 million in FY 1992 dollars.

The Fast Auroral Snapshot (FAST) Small Explorer initiated development in 1991 and launched successfully in August 1996 aboard a Pegasus XL launch vehicle. FAST is providing high resolution data on the Earth's auroras and on how electrical and magnetic forces control them. The flow of electrons, protons, and other ions is being studied with greater sensitivity and spatial discrimination and faster sampling than ever before, using five small, university-provided instruments. FAST data is integrated with the results of other Earth-observing satellites and ground observations.

The Submillimeter Wave Astronomy Satellite (SWAS) Small Explorer initiated development in 1991. The launch of the SWAS mission was delayed from January 1997 to TBD due to the recent (November 1996) failure of the Pegasus launch vehicle. SWAS will provide discrete spectral data for study of the water, molecular oxygen, neutral carbon, and carbon monoxide in dense interstellar clouds, the presence of which is related to the formation of stars. Major participants include the Smithsonian Astrophysical Observatory, the Millitech Corporation, Ball Aerospace, and the University of Cologne, which provides a spectrometer.

The Transition Region and Coronal Explorer (TRACE) Small Explorer initiated development in October 1994 and is scheduled for launch in late 1997. TRACE is a solar science mission that will explore the connections between fine-scale magnetic fields and their associated plasma structures. Observations of solar-surface magnetic fields will be combined with observations showing their effects in the photosphere, chromosphere, transition region and corona. Major participants include the Lockheed Palo Alto Research Laboratory and the Harvard-Smithsonian Center for Astrophysics.

The Wide-field Infrared Explorer (WIRE) Small Explorer also initiated development in October 1994, and is scheduled for launch in late 1998. WIRE will detect starburst galaxies, ultraluminous galaxies, and luminous protogalaxies. Major participants in WIRE include Utah State University, Ball Aerospace, Cornell University, Cal Tech, and the Jet Propulsion Laboratory.

NASA will release an Announcement of Opportunity (OA) in 1997 to select the SMEX missions for launch in 2000 and 2001.

University Class

University-class Explorer (UNEX) missions are currently planned to help NASA achieve a higher future flight rate. UNEX are very small, low-cost missions managed, designed and developed at universities in cooperation with industry. The program will develop greater technical expertise within the academic community beyond the suborbital class missions currently being flown aboard balloons and sounding rockets, thus creating greater opportunity for students and reducing the required role of NASA in-house expertise. UNEX missions will cost only a few million dollars each for definition, development, and operations. UNEX missions will be similar to the Student Explorer Demonstration Initiative (STEDI) missions (SNOE, TERRIERS, and CATSAT) which are under development.

MEASURES OF PERFORMANCE

Advanced Composition Explorer (ACE)

Performance Milestone	Plan	Actual/Revised	Description/Status
Instrument deliveries complete	December 1996	October 1996	All instruments ready for physical integration with the spacecraft
Begin environmental tests	February 1997	--	Following completion of integration, the spacecraft enters its series of electrical, magnetic, vibration, thermal/vacuum, and balance tests. Ahead of schedule.
Ship to KSC	July 1997	--	Spacecraft system level testing successfully complete. Move to KSC for integration with Delta II launch vehicle. Ahead of schedule.
Launch	December 1997	--	Possible earlier launch

Far Ultraviolet Spectroscopy Explorer (FUSE)

Performance Milestone	Plan	Actual/Revised	Description/Status
Mission CDR	April 1996	April 1996	Confirmed that the mission design is sound.
Spacecraft CDR	June 1996	June 1996	Confirmed that design is of sufficient maturity and detail, and is compatible with established interfaces (thermal, structural, etc.). Design frozen prior to initiation of full-scale hardware fabrication.
FUSE Spacecraft I&T	June 1997	--	Begin to assemble and test major components. On schedule
Launch	October 1998	--	On schedule.

Medium-class Explorer Progam

Performance Milestone	Plan	Actual/Revised	Description/Status
Step 2 Selections	March 1996	April 1996	Two missions selected for start of Phase B definition studies.
IMAGE PDR	January 1997	--	Approve for more detailed design analysis, and confirm that science objectives are achievable. On schedule
IMAGE Spacecraft CDR	August 1997	--	Confirmation that the mission design is sound, and that it can move to full-scale development. On schedule.
IMAGE - Begin instrument I&T	February 1998	--	Integrate and test major instrument components. On schedule.
IMAGE - Begin S/C System I&T	August 1998	--	Integrate and test major spacecraft subsystems. On schedule for launch by the first quarter of FY 2000.
MAP Mission PDR	January 1997	--	Confirmation leading to Phase C/D. On schedule.
MAP Mission CDR	July 1997	--	Confirmation that the mission design is sound. On schedule.
MAP - Begin Instrument I&T	October 1997	--	Integrate and test major instrument components. On schedule for launch by the first quarter of FY 2001.

Small-class Explorer Progam

Performance Milestone	Plan	Actual/Revised	Description/Status
Transition Region and Coronal Explorer (TRACE) Start integration and test	August 1996	August 1996	Begin to assemble major components onto the spacecraft
Ship TRACE to launch site	September 1997	--	Move to KSC for integration with the launch vehicle. On schedule.
TRACE Launch	October 1997	--	On schedule, but depends on Pegasus return to flight.
Wide-field Infrared Explorer (WIRE) Start integration and test	October 1997	--	Begin to assemble major components onto the spacecraft. On schedule.
WIRE Launch	August 1998	--	On schedule, but depends on Pegasus return to flight

University-class Explorer Progam

Performance Milestone	Plan	Actual/Revised	Description/Status
Release of AO	2nd Qtr FY 1997	--	Release an Announcement of Opportunity (AO) for the first round of UNEX missions.
Complete selection	4th Qtr FY 1997	--	Select the first round of UNEX missions and initiate development activities
First UNEX mission launch	4th Qtr FY 1999	--	Launch the first UNEX mission aboard an Ultra-Lite Class ELV.

ACCOMPLISHMENTS AND PLANS

ACE spacecraft integration and test started in the summer of 1996. All instruments were delivered to the spacecraft for integration during the latter part of FY 1996 in support of launch no later than December 1997.

Following successful completion of the preliminary design and non-advocate reviews, development of the restructured FUSE mission began in December 1995. A Mission Critical Design Review (CRD) was completed in April 1996, and the Spacecraft CDR was completed in June 1996. Fabrication of the spacecraft and instruments will start in February 1997, leading to integration and test activities in the summer of 1997. The FUSE spacecraft will be delivered to the launch site for final preparations to support launch in October 1998 aboard a Delta 7300s launch vehicle.

The first MIDEX Announcement of Opportunity (AO) was released in March 1995. In Step One of the evaluation process, thirteen proposals were selected in September 1995 for further evaluation. In Step Two of the evaluation process, two of the thirteen proposals were selected for definition study in April 1996. The two missions selected are MAP and IMAGE. Development for these two MIDEX missions starts in FY 1997. Confirmation for development for the IMAGE mission is expected in March 1997, and confirmation of the MAP mission is scheduled for July 1997. Development of the IMAGE and MAP missions will continue throughout FY 1998, including integration and testing of subsystems with the spacecraft structure. IMAGE is targeted for launch in early FY 2000, and the MAP is targeted for an early FY 2001 launch. Both MAP and IMAGE will be launched aboard Med-Lite class launch vehicles. An Announcement of Opportunity (AO) will be released for the next round of the MIDEX program in March 1997.

In the SMEX program, FAST launched successfully in August 1996. SWAS will be launched as soon as possible, following the return to flight status of the Pegasus XL launch vehicle. The development of components for the TRACE and WIRE missions was completed in FY 1996. TRACE launch is scheduled in late 1997, and WIRE launch is scheduled for late 1998, both aboard Pegasus XL launch vehicles. An Announcement of Opportunity (AO) will be released for the next round of the SMEX program in January 1997.

NASA has used the additional FY 1996 UNEX appropriations provided by Congress to fund the Cooperative Astrophysics and Technology Satellite (CATSAT) mission. Additional resources required to fully fund the CATSAT mission have been provided within the Explorers FY 1997 budget. The CATSAT mission was considered as a backup to the first two Student Explorer Demonstration Initiative (STEDI) missions. CATSAT is a small, astrophysics space flight mission specifically designed to solve the puzzle of Gamma Ray Bursts' origin using an innovative multi-observation approach. The development efforts for the CATSAT spacecraft and launch vehicle started in FY 1996, and will continue through FY 1998. CATSAT is developed by the University of New Hampshire. CATSAT is targeted for launch in mid-FY 1998 aboard an Ultra-Lite class ELV.

The University Class Explorer (UNEX) program also initiates in FY 1997. NASA plans to release an Announcement of Opportunity (AO) for the UNEX program in 1997, with the first set of missions selected by the end of the fiscal year. The first of these missions will be developed in FY 1998, and is planned for launch in 1999 aboard an Ultra-Lite class ELV.

BASIS OF FY 1998 FUNDING REQUIREMENT (Thousands of Dollars)	FY 1996	FY 1997	FY 1998
Near Earth Asteroid Rendezvous*	8,300	--	--
Mars Pathfinder *	33,700	--	--
Lunar Prospector *	36,400	19,800	--
Stardust *	13,500	52,200	42,300
Future Missions	10,300	4,800	64,200
Total	102,200	76,800	106,500

* Total cost information is provided in the Special Issues section

PROGRAM GOALS

The Discovery program provides frequent access to space for small planetary missions that will perform high-quality scientific investigations. The program responds to the need for low-cost planetary missions with short development schedules. Emphasis is placed on increased management of the missions by principal investigators. The Discovery program is intended to accomplish its missions while enhancing the U.S. return on its investment and aiding in the national goal to transfer technology to the private sector. It seeks to reduce total mission/life cycle costs and improve performance by using new technology and by controlling design/development and operations costs. A Discovery mission development cost (Phase C/D through launch plus 30 days) must not exceed $150 million (FY 1992 dollars), and the mission must launch within 3 years from start of development. The program also seeks to enhance public awareness of, and appreciation for, space exploration and to provide educational opportunities.

STRATEGY FOR ACHIEVING GOALS

The Near Earth Asteroid Rendezvous (NEAR) mission was an FY 1994 new start, and was developed in-house at the Applied Physics Laboratory (APL), although many subsystems were subcontracted. NEAR was successfully launched on a Delta II launch vehicle on February 17,1996. NEAR will conduct a comprehensive study of the near Earth asteroid 433 EROS, including its physical and geological properties and its chemical and mineralogical composition. The EROS launch opportunity required an accelerated development schedule for NEAR of only 27 months. The spacecraft carries five scientific instruments. The Multispectral Imager (MSI) will provide global imaging coverage as well as detailed views of the asteroid at resolutions as high as one to two meters to reveal details of the geologic processes that have affected its evolution; the X-Ray/Gamma-Ray Spectrometer (XGRS) will provide a chemical analysis by measuring several dozen key elements; the Near Infrared Spectrometer (NIS) will determine the mineral composition of the asteroid's surface; and the Magnetometer, together with radio science, will help characterize its internal structure. The Laser Altimeter (LIDAR) will help determine the shape of the asteroid, distinguish albedo from topographic variations, and measure surface morphology. Tracking and navigation support is being provided by JPL.

The Mars Pathfinder mission was also an FY 1994 new start as an in-house effort at the Jet Propulsion Laboratory (JPL). Pathfinder was successfully launched in December 1996 and will arrive at Mars on July 4, 1997. The mission is designed to demonstrate the cruise, entry, descent, and landing system approach that will be used in future missions to place small science landers on the Martian surface. Pathfinder carries three science instruments and a microrover. The multispectral stereo Imager for Mars Pathfinder (IMP) will characterize the Martian surface morphology and geology at a 1-meter resolution. An Alpha-Proton X-ray Spectrometer (APXS) will obtain information on the elemental composition of Martian rocks and soil. This instrument is carried aboard the microrover. An Atmospheric Structure Instrument and Meteorology package (ASI-Met) will obtain information on the structure of the Martian atmosphere from measurements during entry and descent, and will obtain in-situ meteorology information while deployed on the Martian surface. The lander will also deploy and operate the microrover flight experiment to evaluate the effects of the Martian surface conditions on the rover design and its ability to deploy and operate science instruments. Portions of the science instruments were provided by Germany and Denmark.

The Lunar Prospector mission was selected as the third Discovery mission in FY 1995 with mission management from the NASA Ames Research Center. Lockheed Martin will provide the launch, spacecraft, instruments, and operations. Tracking and communications support will be supplied by the Deep Space Network. The mission is designed to search for resources on the Moon, with special emphasis on the search for water in the shaded polar regions. In addition, the mission will provide accurate gravity and magnetic models of the Moon, supplement the surface data collected by the Galileo and Clementine missions and provide major additions to our understanding of the origin and evolution of the Earth, Moon, and Planets. The spacecraft carries four scientific instruments. The Gamma Ray Spectrometer (GRS) will provide an elemental analysis of the lunar surface by measuring several key elements; the Neutron Spectrometer (NS) will determine the abundance and distribution of hydrogen in the lunar surface which points to the possible water reservoir; the Alpha Particle Spectrometer (APS) will search for gas release events and map their distribution; and the Magnetometer and Electron Reflectometer (MAG/ER) will provide a comprehensive lunar magnetics investigation. In addition, a Doppler gravity experiment (DGE) will be conducted using the spacecraft communications system to provide a map of the lunar gravity field. Launch will be on a Lockheed Launch Vehicle-II in September 1997. The launch window is ten days long and repeats every month.

The Stardust mission was selected as the fourth Discovery mission in November 1995, with mission management from the Jet Propulsion Laboratory. The mission team has completed the Phase B analysis, and Stardust was approved for implementation in October, 1996. The mission is designed to gather samples of dust from the comet Wild-2 and return the samples to Earth for detailed analysis. Stardust will also gather and return samples of interstellar dust that the spacecraft encounters during its trip through the Solar System to fly by the comet. Stardust will use a new material called aerogel to capture the dust samples. In addition to the aerogel collectors, Stardust will carry three additional scientific instruments. An optical camera will return images of the comet; the Cometary and Interstellar Dust Analyzer (CIDA) is provided by Germany to perform basic compositional analysis of the samples while in flight; and a dust flux monitor will be used to sense particle impacts on the spacecraft. Stardust will be launched on the Med-Lite expendable launch vehicle in February 1999 with return of the samples to Earth in January 2006.

Discovery mission development is managed within an essentially level funding profile. New mission starts are therefore subject to availability of sufficient funding in order to stay within the total program budget. Funding for mission studies is also provided within the Discovery budget.

MEASURES OF PERFORMANCE

Mars Pathfinder

Performance Milestone	Plan	Actual/Revised	Description/Status
Flight qualification complete	December 1995	June 1996	Performance testing of major elements of Entry, Descent and Landing (EDL) subsystem (airbag, aeroshell, chute, etc.) was extended to assure survivability of the payload during Mars landing. Tests completed in June 1996.
Pre-ship Review (PSR)	August 1996	August 1996	Spacecraft shipped to Kennedy Space Center (KSC) in August 1996 for integration with Delta II launch vehicle.
Launch	December 1996	December 1996	Development phase complete; successful launch.

Lunar Prospector

Performance Milestone	Plan	Actual/Revised	Description/Status
Instrument Delivery for I&T	October 1996	November 1996	Flight model spacecraft subsystems and instruments completed. Begin system level integration and test phase.
Test Readiness Review	November 1996	November 1996	Flight System test Readiness Review ensures that the flight systems are prepared for environmental testing.
Launch	October 1997	September 1997	Development phase complete; start of mission. Now scheduled for September 1997, accelerated one month, to avoid potential launch pad conflicts with Cassini.

Stardust

Performance Milestone	Plan	Actual/Revised	Description/Status
System Requirements Review	April 1996	April 1996	Ensures mission requirements can be met with current technology and expected developments.
Technical Design Review	October 1996	September 1996	Review assured readiness to proceed with detailed design and development.
Preliminary Design Review (PDR)	October 1996	September 1996	Review confirmed that proposed project baseline meets all program-level performance requirements and represents acceptable level of cost and technical risk.
Critical Design Review	June 1997	--	Confirms that the project system, subsystem, and component designs are of sufficient detail to allow for orderly hardware and software manufacturing, integration and testing, with acceptable risk. Successful completion freezes the design prior to initiation of fabrication, integration, and test. On schedule.
Start Spacecraft Assembly and Test	January 1998	--	Begin to integrate major components of the spacecraft onto the spacecraft structure. On schedule.
Start environmental tests	June 1998	--	Begin tests to demonstrate that the assembled spacecraft can withstand the launch and space environments. On schedule.

ACCOMPLISHMENTS AND PLANS

NEAR launched successfully in February 1996.

The assembled Mars Pathfinder spacecraft was delivered to the launch site in August 1996 and successfully launched by a Delta II vehicle in December 1996.

The Lunar Prospector Phase B design activities were completed in October 1995. A successful Technical Design Review was conducted at the end of Phase B, prior to initiating Phase C/D. Orders for procurement of major subsystems have been completed. Fabrication and integration of the scientific instruments began in September 1996. Integration and test of the complete spacecraft is planned to be completed by May 1997. Launch readiness has been accelerated one month to September 1997, in order to avoid a potential launch pad conflict with Cassini in October.

The Stardust mission was selected as the fourth Discovery mission in November 1995. Phase A study activities were completed in October 1995, and Phase B analysis activities have been initiated. A technical design review was accomplished in September 1996, and the program started Phase C/D in November 1996. Assembly and test of spacecraft components will continue until late in calendar year 1997. Integration of components into the spacecraft will occur in early CY 1998, leading to the start of environmental testing late in FY 1998.

Additional resources are requested in FY 1997 and beyond to study and initiate development of future Discovery missions. Announcements of Opportunity will be released on a regular basis. An Announcement of Opportunity was released in September 1996, and proposals are currently under evaluation. FY 1997 funds will allow for Phase A studies of selected proposals, leading to a selection late this fiscal year. Detailed Phase B studies of the selected missions will begin in October, and Phase C/D development will begin later in FY 1998.

BASIS OF FY 1998 FUNDING REQUIREMENT (Thousands of Dollars)	FY 1996	FY 1997	FY 1998
Mars Global Surveyor	58,100	--	--
Mars Surveyor 98 Orbiter and Lander	52,400	86,900	40,500
Future Missions	1,400	3,100	99,200
Total	111,900	90,000	139,700

* Total cost information is provided in the Special Issues section

PROGRAM GOALS

Mars has been a primary focus for scientists due to its potential for past biological activity and for comparative studies with Earth. The Mars Surveyor program is a series of small missions designed to resume the detailed exploration of Mars. Missions are planned for launch at every launch opportunity; opportunities occur about every 26 months due to the orbital periods of Earth and Mars. In the near term, missions may either orbit Mars to perform mapping of the planet and its space environment, or actually land on the planet to perform science from the surface. A long-term goal is to perform a sample return mission, returning Mars rocks for analysis. Earlier missions will facilitate this long-range goal by identifying those areas of Mars which are most likely to contain samples of scientific importance, including (potentially) evidence of past biological activity.

STRATEGY FOR ACHIEVING GOALS

This program began in FY 1994 with the development of the Mars Global Surveyor, an orbiter which will obtain much of the data that would have been obtained from the Mars Observer mission. The orbiter will fly a science payload, comprised of spare Mars Observer instruments aboard a small, industry-developed spacecraft. MGS was launched in November 1996 aboard a Delta II launch vehicle and placed on a trajectory to Mars. The spacecraft will arrive at Mars in September 1997, and begin mapping operations in January, 1998. This mission is to be succeeded by a series of small orbiters and landers which will make in-situ measurements of the Martian climate and soil composition. Technology developed by the Mars Pathfinder mission will be optimized to reduce lander mission costs and technical risk. An orbiter launch is planned in December 1998, a lander launch in January 1999, two launches in the February 2001 opportunity, and launches in the 2003 and 2005 opportunities. The Mars Surveyor program has been augmented in FY 1998 and beyond to permit acceleration of a sample return mission from FY 2007 to FY 2005, while maintaining the ability to develop and launch two spacecraft (an orbiter and a lander) at each opportunity through 2003.

Mars Surveyor mission development is managed within an essentially fixed funding profile. New mission starts are therefore subject to availability of sufficient funding in order to stay within the total program budget. Funding for mission studies is also provided within the Mars Surveyor budget.

MEASURES OF PERFORMANCE

Mars Global Surveyor

Performance Milestone	Plan	Actual/Revised	Description/Status
Instrument Calibration and Test	December 1995	May 1996	Instrument integration completed. Instruments operated under simulated flight conditions to validate/characterize performance against design specifications. Completion rescheduled to May 1996 without impact to launch.
Instrument deliveries	February 1996	May 1996	Instruments begin delivery to Lockheed Martin for integration with spacecraft prior to initiation of system level testing. Completion rescheduled to May 1996 without impact to launch date.
System Acceptance Review	August 1996	August 1996	Assure that flight hardware integration is complete and ready for final acceptance tests.
Operational Readiness Review	October 1996	August 1996	Formal review approving test results and recommending mission launch. Schedule accelerated to August 1996.
Launch	November 1996	November 1996	Launched November 7, 1996. Spacecraft in cruise mode to Mars.

1998 Mars Surveyor Orbiter and Lander

Performance Milestone	Plan	Actual/Revised	Description/Status
Preliminary Design Review (PDR)	March 1996	March 1996	Review held in March 1996 which confirmed that the project baseline met all program-level performance requirements and represented acceptable levels of cost and technical risk.
Payload Confirmation Review	April 1996	April 1996	Confirmed that tentatively selected payload can be accommodated within the spacecraft specifications.
Spacecraft Systems Critical --Design Review (CDR)	January 1997	--	Confirms that spacecraft system, subsystem and component designs are sufficiently mature, compatible with established interfaces (structural, thermal, electrical, etc.), and represent appropriate levels of cost, schedule and technical risk. On schedule.
Start Orbiter Integration and Test	May 1997	--	Integrate instruments and spacecraft subsystems. On schedule.
Start Lander Integration and Test	July 1997	--	Integrate instruments and spacecraft subsystems. On schedule
Start Lander environmental tests	November 1997	--	Confirm that the spacecraft can tolerate the launch and mission environments that it will face. On schedule.
Start Orbiter environmental tests	November 1997	--	Confirm that the spacecraft can tolerate the launch and mission environments that it will face. On schedule.
Ship Orbiter spacecraft	August 1998	--	Ship to the launch site. On schedule for December 1998 launch.

2001 Mars Surveyor Orbiter and Lander

Performance Milestone	Plan	Actual/Revised	Description/Status
Release of AO	3rd Qtr FY 1997	--	Release an Announcement of Opportunity (AO) for Mars Surveyor 2001 mission.
Start mission/flight system definition	3rd Qtr FY 1997	--	Begin definition study for the mission and flight system
Science Instrument selection	1st Qtr FY 1998	--	Select the Science Instrument(s) to be flown on 2001 Mars Surveyor
Complete Phase B and start C/D	3rd Qtr FY 1998	--	Complete definition study and initiate the development effort.

Performance Milestone

Plan

Actual/Revised

Description/Stat