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SPACE
FLIGHT 2004 - United States Space Activities
Dr. Jesco von Puttkamer
Space Shuttle |
Advanced transportation systems activities
Space sciences and astronomy
Gravity Probe-B | MESSENGER
| Swift| GALEX | Spitzer Space Telescope
| RHESSI | Hubble Space Telescope |
Chandra Observatory | Cassini/Huygens
| WMAP | Genesis | ACE
| Stardust | Ulysses
| Voyager
Mars exploration
Earth Science
Aura |ICESat|Aqua
|POES-M |GRACE |
Department of Defense space activities | Commercial space
activities
Launch activities in the United States in 2004 showed a sizable decrease from the relatively elevated level of the previous year. There were 19 NASA, DOD, and commercial launches, out of 19 attempts (2003: 26 of 27 attempts [loss of Columbia]; 2002: 18 of 18).
Space Shuttle.
Because of the loss of Orbiter Columbia on the first shuttle mission
in 2003, operations with the reusable shuttle vehicles of the U.S.
Space Transportation System (STS) came to a halt for the remainder
of the year and for 2004, as NASA and its contractors labored on
intensive Return to Flight (RTF) efforts, with resumption of shuttle
flights not expected until mid-2005. Resupply and crew rotation
flights to the ISS were taken over solely by Russian Soyuz and Progress
vehicles.
Advanced transportation
systems activities. NASA's study activities of the
original five-year Space Launch Initiative (SLI) project, announced
in 2001, for developing the technologies to be used to build an
operational reusable launch vehicle (RLV) before 2015 were terminated
when in 2004 President George W. Bush announced NASA’s new long-range
Vision for Space Exploration. New study activities will focus on
concepts of the Vision’s CEV (Crew Exploration Vehicle) and heavy
cargo lifters, with the goal to retire the space shuttle by 2010.
Space sciences and astronomy.
In 2004, the U.S. launched four civil science spacecraft, one less
than in the previous year: Gravity Probe-B, Aura, Messenger, and
Swift.
Gravity Probe-B. Gravity
Probe-B (GP-B) is a NASA mission to test two predictions of
Albert Einstein's Theory of General Relativity. Launched on April
20 (9:57:24am PDT) on a Delta 2 rocket, the 3100-kg spacecraft,
orbiting 400 miles above Earth, uses four ultra-precise gyroscopes
to test Einstein's theory that space and time are distorted by the
presence of massive objects. To accomplish this, the mission measures
two fa ctors: how space and time are warped by the presence of the
Earth, and how the Earth's rotation drags space-time around with
it. In early September, the probe achieved a major milestone with
the completion of the Initialization & Orbit Calibration (IOC) phase
of its mission and the transition into the science phase, bringing
the GP-B mission one step closer to shedding new light on the fundamental
properties of our universe. NASA's Marshall Space Flight Center
manages the GP-B program, with Stanford University, the prime mission
contractor, who conceived the experiment, responsible for the design
and integration of the science instrument, as well as for mission
operations and data analysis. Lockheed Martin, a major subcontractor,
designed, integrated and tested the space vehicle and built some
of its major payload components.
MESSENGER.NASA's MESSENGER
(Mercury Surface, Space Environment, Geochemistry, and Ranging)
- set to become the first spacecraft to orbit the planet Mercury
- was launched on August 3 (at 2:15:56am EDT) aboard a Delta 2 rocket
from Cape Canaveral Air Force Station, Fla. The approximately 1.2-ton
(1,100-kilogram) spacecraft, designed and built by the Johns Hopkins
University Applied Physics Laboratory (APL) in Laurel, MD, was placed
into a solar orbit 57 minutes after launch, targeted to begin orbiting
Mercury in 2011. During a 4.9-billion mile (7.9-billion kilometer)
journey that includes 15 trips around the sun, MESSENGER will fly
past Earth once, Venus twice and Mercury three times before easing
into orbit around its target planet. The Earth flyby, on August
2, 2005, and the Venus flybys, in October 2006 and June 2007, will
use the pull of the planets' gravity to guide MESSENGER toward Mercury's
orbit. The Mercury flybys in January 2008, October 2008 and September
2009 help the probe match the planet's speed and location for an
orbit insertion maneuver in March 2011. The flybys also allow the
spacecraft to gather data critical to planning a yearlong orbit
phase. Since MESSENGER is only the second spacecraft sent to Mercury
- Mariner 10 flew past it three times in 1974-75 and gathered detailed
data on less than half the surface - the mission has an ambitious
science plan. With a package of seven science instruments MESSENGER
will determine Mercury's composition; image its surface globally
and in color; map its magnetic field and measure the properties
of its core; explore the mysterious polar deposits to learn whether
ice lurks in permanently shadowed regions; and characterize Mercury's
tenuous atmosphere and Earth-like magnetosphere.
Swift.NASA's
Swift satellite successfully launched on November 20 (12:16pm
EST) aboard a Delta 2 rocket from Launch Complex 17A at the Cape
Canaveral Air Force Station, Fla. The satellite was designed and
built with international participation (England, Italy) to solve
the 35-year-old mystery of the origin of gamma-ray bursts (GRBs).
Scientists believe the bursts, distant yet fleeting explosions,
are related to the formation of black holes throughout the universe
- the birth cries of black holes. Each gamma-ray burst is a short-lived
event, lasting only a few milliseconds to a few minutes, never to
appear again. They occur several times daily somewhere in the universe,
and Swift should detect several weekly. To track these mysterious
bursts, Swift carries a suite of three main instruments. The Burst
Alert Telescope (BAT) instrument, built by Goddard, will detect
and locate about two gamma-ray bursts weekly, relaying a rough position
to the ground within 20 seconds. The satellite will swiftly re-point
itself to bring the burst area into the narrower fields of view
of the on-board X-ray Telescope (XRT) and the UltraViolet/Optical
Telescope (UVOT). These telescopes study the afterglow of the burst
produced by the cooling ashes that remain from the original explosion.
During its 2-year mission, Swift is expected to observe more than
200 gamma-ray bursts - the most comprehensive study of GRB afterglows
to date.
GALEX.GALEX (Galaxy Evolution
Explorer), launched by NASA on April 28, 2003, on a Pegasus XL rocket
from a L-1011 aircraft into a nearly circular Earth orbit, is an
orbiting space telescope for observing tens of millions of star-forming
galaxies in ultraviolet (UV) light across 10 billion years of cosmic
history. Its telescope has a basic design similar to the Hubble
Space Telescope (HST), but while HST views the sky in exquisite
detail in a narrow field of view - like a grain of sand held at
arm's length - the GALEX telescope is tailored to view hundreds
of galaxies in each observation. Thus, it requires a large field
of view, rather than high resolution, in order to efficiently perform
the mission's surveys. During 2004, among else, astronomers using
GALEX’s sensitive ultraviolet detectors have detected three-dozen
bright, compact galaxies that greatly resemble the youthful galaxies
of more than 10 billions years ago. These new galaxies are relatively
close to us, ranging from two to four billion light-years away.
They may be as young as 100 million to one billion years old (the
Milky Way is approximately 10 billion years old). This discovery
suggests our aging universe is still alive with youth. It also offers
astronomers their first, close-up glimpse at what our galaxy probably
looked like when it was in its infancy.
Spitzer Space Telescope (SST), formerly
known as SIRTF (Space Infrared Telescope Facility) and launched
on August 24, 2003, is the fourth and final element in NASA's family
of Great Observatories and represents an important scientific and
technical bridge to NASA's Astronomical Search for Origins program.
The Observatory carries an 85-cm cryogenic telescope and three cryogenically
cooled science instruments capable of performing imaging and spectroscopy
in the 3.6 to 160 micron range. Its supply of liquid helium for
radiative-cryogenic cooling was estimated post-launch to last for
about 5.8 years, assuming optimized operation. In 2004, among else,
Spitzer discovered
for the first time dusty discs around mature, Sun-like stars known
to have planets, and the Hubble Space Telescope captured the most
detailed image ever of a brighter disc circling a much younger Sun-like
star. The findings offer "snapshots" of the process by
which our own solar system evolved, from its dusty and chaotic beginnings
to its more settled present-day state. The young star observed by
Hubble is 50 million to 250 million years old. This is old enough
to theoretically have gas planets, but young enough that rocky planets
like Earth may still be forming. The six older stars studied by
Spitzer average 4 billion years old, nearly the same age as the
Sun. They are known to have gas planets, and rocky planets may also
be present. Prior to these findings, rings of planetary debris,
or "debris discs," around stars the size of the Sun had
rarely been observed, because they are fainter and more difficult
to see than those around more massive stars. Debris discs around
older stars the same size and age as our Sun, including those hosting
known planets, are even harder to detect. These discs are 10 to
100 times thinner than the ones around young stars. Spitzer's highly
sensitive infrared detectors were able to sense their warm glow
for the first time.
RHESSI.RHESSI (Reuven Ramaty
High Energy Solar Spectroscopic Imager, in honor of the late NASA
scientist who pioneered the fields of solar-flare physics, gamma-ray
astronomy and cosmic ray research), launched on February 5, 2002,
in 2004 continued its operation in Earth orbit, providing advanced
images and spectra to explore the basic physics of particle acceleration
and explosive energy release in solar flares. Since its launch the
spacecraft has been very successful observing solar flares, which
are capable of releasing as much energy as a billion one-megaton
nuclear bombs. In 2004, among else, RHESSI was taken off the Sun
to point at the Crab Nebula, to obtain the finest imaging ever done
of a cosmic source in the hard x-ray/soft gamma-ray range.
Hubble Space Telescope. Fourteen
years after it was placed in orbit, the Hubble Space Telescope (HST)
continued to probe far beyond the Solar System, producing imagery
and data useful across a range of astronomical disciplines to expand
our knowledge of the universe. Hubble was and is making discoveries
at a rate that is unprecedented for a single observatory, and its
contributions to astronomy and cosmology are wide-ranging. In 2004,
scientists using the HST measured the age of what may be the youngest
galaxy ever seen in the universe. Called I Zwicky 18, at a distance
of 45 million light years, it may be as young as 500 million years
old (so recent an epoch that complex life had already begun to appear
on Earth). The Milky Way galaxy by contrast is over 20 times older,
or about 12 billion years old, the typical age of galaxies across
the universe. This "late-life" galaxy offers a rare glimpse into
what the first diminutive galaxies in the early universe look like.
On Jupiter, HST spotted a rare triple eclipse: a rare alignment
of three of Jupiter's largest moons – Io, Ganymede, and Callisto
– across the planet's face. Other momentous accomplishments of the
HST in 2004 were the explosion of a massive star blazing with the
light of 200 million Suns, called a supernova. The supernova is
so bright that it easily could be mistaken for a foreground star
in the Milky Way, but in reality this supernova, called SN 2004dj,
resides far beyond our galaxy,- in the outskirts of NGC 2403, a
galaxy located 11 million light-years from Earth. Although the supernova
is far from Earth, it is the closest stellar explosion. In 2004,
design activities continued on the HST’s successor, the James Webb
Space Telescope (JWST), by a contracting team headed by Northrop
Grumman Space Technology, selected in 2002. Plans are to launch
the giant new cosmic telescope (5,400 kg/11,880 lbs) in 2011 on
a European Ariane 5 toward the second Lagrangian point (L2), 1.5
million km (930,000 miles) beyond Earth’s orbit on the Sun-Earth
line, where effects of their light on its optics are minimized and
gravitational pull is relatively well balanced.
Chandra Observatory. Launched
on shuttle mission STS-93 on July 23, 1999, the massive (12,930
lbs/5,870 kg) Chandra X-ray Observatory uses a high-resolution camera,
high-resolution mirrors and a charge-coupled detector (CCD) imaging
spectrometer to observe X-rays of some of the most violent phenomena
in the universe which cannot be seen by the Hubble's visual-range
telescope. Throughout its fourth year of operation, Chandra continued
to provide scientists with views of the high-energy universe never
seen before which potentially revolutionize astronomical and cosmological
concepts. After NASA had formally extended the operational mission
of Chandra from five years to 10 years in September 2001 (including
the science grants that fund astronomers to analyze their data and
publish their results), in 2004 Chandra’s most popular image was
a spectacular new image of Cassiopeia A that had nearly 200 times
more data than the "First Light" Chandra image of this object made
five years ago. The new image reveals clues that the initial explosion
caused by the collapse of a massive star was far more complicated
than suspected. Also in 2004, an international team of scientists
used Chandra data to measure the temperature of the pulsar at the
center of 3C58, the remains of a star observed to explode in the
year 1181. Chandra's image of 3C58 also showed spectacular jets,
rings and magnetized loops of high-energy particles generated by
the pulsar. Data indicated that the surface of the 3C58 pulsar has
cooled to a temperature of slightly less than a million degrees
Celsius, which is extremely cool for a young neutron star. Pulsars
are formed when the central core of a massive star collapses to
create a dense object about 15 miles across that is composed almost
entirely of neutrons. Collisions between neutrons and other subatomic
particles in the interior of the star produce neutrinos that carry
away energy as they escape from the star. This cooling process depends
critically on the density and type of particles in the interior,
so measurements of the surface temperature of pulsars provide a
way to probe extreme conditions where densities are so high that
our current understanding of how particles interact with one another
is limited. They represent the maximum densities that can be attained
before the star collapses to form a black hole.
Cassini/Huygens. NASA’s
six-ton (5.4-metric-ton) spacecraft Cassini
continued its epic 6.7-year, 3.2-billion-km journey to the planet
Saturn. During 2004, the spacecraft remained in excellent health
and successfully entered orbit around Saturn on June 30, when at
9:12pm PDT flight controllers received confirmation that Cassini
had completed the engine burn needed to place the spacecraft into
the correct orbit. This began a four-year study of the giant planet,
its majestic rings and 31 known moons. Already in August, the probe
discovered two new moons, approximately 3 kilometers (2 miles) and
4 kilometers (2.5 miles) across -- smaller than the city of Boulder,
CO. The moons, located 194,000 kilometers (120,000 miles) and 211,000
kilometers (131,000 miles) from the planet's center, are between
the orbits of two other Saturnian moons, Mimas and Enceladus. They
were provisionally named S/2004 S1 and S/2004 S2. One of them, S/2004
S1, may be an object spotted in a single image taken by NASA's Voyager
spacecraft 23 years ago, called at that time S/1981 S14. Pictures
and data taken during the first close flyby of Saturn's moon Titan
by Cassini revealed greater surface detail than ever before and
showed that Titan has lost much of its original atmosphere over
time. The surface appears to have been shaped by multiple geologic
processes. Although a few circular features can be seen, none can
be definitively identified as impact craters. On December 24, the
Huygens probe successfully detached from NASA's Cassini orbiter
to begin a three-week journey to Saturn’s moon Titan. NASA's Deep
Space Network tracking stations in Madrid, Spain, and Goldstone,
Calif., received the signal at 7:24pm PST. The Huygens probe, built
and managed by ESA, was bolted to Cassini and has been riding along
during the nearly seven-year journey to Saturn largely in a "sleep"
mode. Set to touch on Titan on January 14, 2005, Huygens will be
the first human-made object to explore on-site the unique environment
of this moon, whose chemistry is assumed to be very similar to that
of early Earth before life formed. By end-2004, its mothership had
found Saturn roiled with storms, detected lighting, discovered a
new radiation belt, found four new moons, a new ring around the
planet and mapped the composition of the planet’s rings. On December
31, Cassini capped off the year with an encounter of Saturn's "yin-yang"
moon Iapetus, on the probe’s closest pass yet by one of Saturn’s
smaller icy satellites since its arrival around the ringed giant.
The next close flyby of Iapetus, a world of sharp contrasts, is
not until 2007. Its leading hemisphere is as dark as a freshly-tarred
street, and the white, trailing hemisphere resembles freshly-fallen
snow, resembling the yin-yang symbol.
WMAP. NASA's Wilkinson
Microwave Anisotropy Probe (formerly called the Microwave Anisotropy
Mission, MAP) was launched on June 30, 2001, on a Delta-2. Now located
in an orbit around the second Lagrange libration point L2, its differential
radiometers measure the temperature fluctuations of the cosmic microwave
background radiation (CMBR) with unprecedented accuracy. The CMBR
is the light left over from the Big Bang, bathing the whole Universe
in this afterglow light. It is the oldest light in the Universe,
having traveled across the cosmos for 14 billion years, and the
patterns in this light across the sky encode a wealth of details
about the history, shape, content, and ultimate fate of the Universe.
Since start of WMAP operations, scientists produced the first version
of a full sky map of the faint anisotropy or variations in the CMBR's
temperature (now averaging at a frigid 2.73 degrees above absolute
zero). Results to date indicate that the Universe is 13.7 billion
years old, with a margin of error of close to 1%, the first stars
ignited 200 million years after the Big Bang, light gathered in
revealing WMAP pictures is from 379,000 years after the Big Bang,
and the Universe consists of 4% atoms, 23% cold dark matter and
73% dark energy. The data places new constraints on the dark energy,
which now seems more like a "cosmological constant" than a negative-pressure
energy field called "quintessence" (the latter however is not ruled
out). Fast moving neutrinos do not play any major role in the evolution
of structure in the universe (they would have prevented the early
clumping of gas in the Universe, delaying the emergence of the first
stars, in conflict with the new WMAP data). The expansion rate of
the Universe, called the Hubble Constant, is Ho= 71 km/sec/Mpc (megaparsecs)
with a margin of error of about 5%. There is new evidence for Inflation
(in polarized signal), and for the theory that fits all data, the
Universe will expand forever. (But the nature of the dark energy
remains a mystery. If it changes with time, or if other unknown
and unexpected things happen in the universe, this conclusion could
change.)
Genesis. The solar probe
Genesis was launched on August 8, 2001, on a Delta 2 rocket into
a perfect orbit about the first Earth-Sun Lagrangian libration point
L1 about 1.5 million km from Earth and 148.5 million km from the
Sun on November 16, 2001. After an unconventional "Lissajous Orbit
Insertion" (LOI), Genesis began the first of five "halo" loops around
L1, lasting about 30 months. Collection of samples of solar wind
material expelled from the Sun started on October 21, 2001. One
year later, on December 10, 2002, with the spacecraft in overall
good health and spinning at 1.6 rotations per minute, its orbit
around L1 was fine-tuned with the seventh of 15 planned station-keeping
maneuvers during the lifetime of the mission. Throughout 2003, Genesis
continued its mission of collecting solar wind material, with all
spacecraft subsystems still reported in excellent health. In April
2004, the sample collectors were deactivated and stowed, and the
spacecraft returned to Earth, where the sample return capsule was
to be recovered in mid-air by helicopter over the Utah Test & Training
Range on September 8, 2004. However, Genesis’ return did not go
according to plan. The vessel, which had spent 27 months collecting
data and samples of the solar wind, entered Earth's atmosphere as
scheduled on 9/8, but its parachutes failed to deploy and the capsule
crashed into the Utah desert at nearly 200 miles an hour. After
the crash, the 400-pound capsule was recovered and transported by
helicopter to a nearby Army base equipped with a clean room for
analysis. In October scientists reported that a large amount of
material within the Genesis scientific collectors had remained intact
and will provide useful information about the beginning and development
of our solar system.
ACE. The
Advanced Composition Explorer (ACE), launched on August 25,
1997, is positioned in a halo orbit around L1, where gravitational
forces are in equilibrium. ACE in 2004 continued to observe, determine
and compare the isotopic and elemental composition of several distinct
samples of matter, including the solar corona, the interplanetary
medium, the local interstellar medium and galactic matter. With
a semi-major axis of approximately 200,000 km, its elliptical orbit
affords ACE a prime view of the Sun and the galactic regions beyond,
from a vantage point approximately 1/100th of the distance from
the Earth to the Sun. The spacecraft has enough propellant on board
to maintain an orbit at L1 until ~2019. By end-2004, ACE has been
at the L1 point for more than 7 years, and things were still working
very well, with the exception of the SEPICA (Solar Energetic Particle
Ionic Charge Analyzer) instrument. SEPICA had trouble with the gas
regulation of its proportional counters and with a high-voltage
power supply. Two-thirds of the instrument were non-functional,
but the third counter was returning good science data. The problems
are still under investigation. As of Spring 2004, over 350 peer
reviewed papers had been published by ACE science team members.
Stardust. In January 2004,
having weathered a strong “sandblasting” by cometary particles hurtling
toward it at about six times the speed of a rifle bullet, NASA's
comet probe Stardust
spacecraft, launched on February 3, 1999 on a Delta 2, passed by
Comet P/Wild 2, collected particles and began its two-year, 1.14
billion kilometer (708 million mile) trek back to Earth. The probe
had entered the comet's coma - the vast cloud of dust and gas that
surrounds a comet's nucleus - on December 31, 2003. From that point
on it kept its defensive shielding between it and what scientists
hoped would be the caustic stream of particles it would fly through.
Before its closest approach to the comet, Stardust's trajectory
made three loops around the Sun. After one solar orbit, an Earth
flyby was used to boost the spacecraft orbit on January 15, 2001
and a second period of interstellar dust collection was opened July
to December 2002. On November 2, 2002 Stardust passed within 3000
km of asteroid 5535 Anne Frank, at 7 km/sec relative velocity. A
second orbit of the sun was completed in mid-2003 and the comet
P/Wild 2 encounter followed then on January 2, 2004, with a closest
approach of about 150 km at a relative velocity of about 6.1 km/sec,
at 1.85 AU (astronomical units) from the Sun and 2.6 AU from Earth.
The sample collector was deployed in late December 2003 and retracted,
stowed, and sealed in the vault of the sample reentry capsule after
the Wild fly-by. Images of the comet nucleus were also obtained,
with coverage of the entire sunlit side at a resolution of 30 m
or better. On January 15, 2006 the capsule will separate from the
main craft (with a stabilizing spin of 1.5 rpm) and re-enter Earth's
atmosphere. A parachute will be deployed, and a chase aircraft will
“snatch” and recover the descending capsule over the U.S. Air Force
Test & Training Range in the Utah desert. Special engineering analyses
were performed to ensure that Stardust will not suffer the same
fate as Genesis.
Ulysses. In 2004, the joint
European/NASA solar polar mission Ulysses continued. Launched in
1990 on shuttle mission STS-41 to study the Sun’s polar regions,
the mission in 2004 was in its 14th year, and all spacecraft systems
and the nine sets of scientific instruments remain in excellent
health. Ulysses arrived over the sun's south polar regions for the
second time in November 2000, followed by the rapid transit from
maximum southern to maximum northern helio-latitudes that was completed
in October 2001. Solar activity reached its maximum in 2000, so
that Ulysses experienced a very different high-latitude environment
from the one it encountered during the first high-latitude passes.
In June 2004, the spacecraft again reached aphelion, its farthest
point from the sun, after passing through its critical eighth conjunction
on August 30, 2003 (where Earth, Sun and spacecraft are aligned
with the Sun in the middle). Ulysses' signals are transmitted to
its operations center at NASA’s Jet Propulsion Laboratory in Pasadena,
California. In February 2004, ESA's Science Program Committee unanimously
approved a proposal to continue operating the highly successful
Ulysses spacecraft until March 2008. This latest extension, the
third in the history of the joint ESA-NASA mission, will enable
Ulysses to add an important chapter to its survey of the high-latitude
heliosphere. In 2007 and 2008, the space probe will fly over the
poles of the Sun for a third time. Unlike the past high-latitude
passes in 2000 and 2001 that brought Ulysses over the solar poles
near the maximum of the Sun's activity cycle, conditions for the
third set of polar passes are expected to be much quieter. In fact,
they are likely to be similar to those in 1994/1995 when Ulysses
first visited the Sun's poles.
Voyager. The Voyager
mission, now in its 28th year, continues its quest to push the
bounds of space exploration. The twin Voyager
1 and 2
spacecraft opened new vistas in space by greatly expanding our knowledge
of Jupiter and Saturn. Voyager 2 then extended the planetary adventure
when it flew by Uranus and Neptune, becoming the only spacecraft
ever to visit these worlds. In 2003, Voyager 1 set a new milestone,
when on November 5 the spacecraft reached 90 astronomical units
(AU) from the Sun (i.e., about 8.4 billion miles or 13.5 billion
kilometers). Voyager 1 is the most distant human-made object in
the universe. At end-2004, the spacecraft was about 94 times as
far from the Sun as is Earth. It was deflected northward above the
plane of the planets' orbits when it swung by Saturn in 1980 and
is now speeding outward from the Sun at nearly one million miles
per day, a rate that would take it from Los Angeles to New York
in less than four minutes. Long-lived nuclear batteries are expected
to provide electrical power until at least 2020 when Voyager 1 will
be more than 13 billion miles from Earth and may have reached interstellar
space. The only spacecraft to have made measurements in the solar
wind from such a great distance from the source of the dynamic solar
environment, it is now at 8.7 billion miles from the Sun and has
entered the solar system's final frontier, the so-called heliosheath
beyond the termination shock of the solar wind, a vast, turbulent
expanse where the Sun's influence ends and the solar wind crashes
into the thin gas between stars. Close on the heels of its twin
ship, Voyager 2 also continues the groundbreaking journey with the
current mission to study the region in space where the Sun's influence
ends and the dark recesses of interstellar space begin. In July
2003, Voyager 2 had reached a distance from the Sun of 10.6 billion
km (70 AU). At end-2004 (exactly on January 5, 2005) it was 10,000
days since Voyager 2's launch. It too continues to go strong, returning
valuable science data. Each Voyager's cosmic ray detector, magnetometer,
plasma wave detector and low-energy charged particle detector all
still operational. In addition, the Ultraviolet Spectrometer on
Voyager 1 and the Plasma Science instrument on Voyager 2 are producing
and transmitting data. Both spacecraft are expected to continue
to operate and send back valuable data until at least the year 2020.
Mars exploration. The year 2004
began with the successful landing and deployment of the two Mars
Exploration Rovers Spirit
and Opportunity,
after their headline-making launches in 2003, at near-equatorial
locations on opposite sides of Planet Mars. The interplanetary navigation
systems enabled exceptionally accurate achievement of the desired
atmospheric entry conditions for both mobile geology laboratories,
and the actual surface landing points differed from the targets
by only 10 km for Spirit and 25 km for Opportunity. In April 2004,
both rovers successfully completed their primary three-month missions
and went into bonus overtime work for the remainder of the year.
Spirit
(MER-A). The six-wheeled rover vehicle Spirit, launched on June
10, 2003, on a Delta 2 Heavy rocket, landed on January 3 (Eastern
Time) almost exactly at its intended landing site in Gusev Crater
in excellent condition. During 2004, Spirit completed a two-mile
trek to a formation called Columbia Hills (after the lost shuttle),
where it found a water-signature mineral called goethite in bedrock,
one of the mission's surest indicators yet for a wet history on
Spirit's side of Mars. Spirit, during its primary mission, explored
a plain strewn with volcanic rocks and pocked with impact craters.
It found indications that small amounts of water may have gotten
into cracks in the rocks and may also have affected some of the
rocks’ surfaces. This did not indicate a particularly favorable
past environment for life. Spirit’s Extended Mission began with
the rover starting a long trek toward a range of hills on the horizon
whose rocks might have come from an earlier and wetter era of the
region’s past. In late September 2004, NASA approved a second extension
of the rovers’ missions. The solar-powered machines were still in
good health, though beginning to show signs of aging. They had come
through the worst days of the Martian year from a solar-energy standpoint.
Also, they had resumed full operations after about two weeks of
not driving in mid-September while communications were unreliable
because Mars was passing nearly behind the Sun. Spirit had driven
3.6 kilometers (2.25 miles), six times the goal set in advance as
a criterion for a successful mission. It was climbing hills where
its examinations of exposed bedrock found more extensive alteration
by water than what the rover had seen in rocks on the younger plain.
During the long trek, Spirit’s right front wheel developed excessive
friction. Controllers found a way to press on with the exploration
by sometimes driving the rover in reverse with the balky wheel dragging.
Opportunity (MER-B). NASA’s second Mars explorer, twin to Spirit,
launched on July 7 (Eastern), also on a Delta 2 Heavy after a “cliffhanger”
countdown, touched down on January 25, 2004, right on target on
Meridiani Planum, halfway around the planet from the Gusev Crater
site of its twin, also in excellent condition. Opportunity had driven
about 1.6 kilometers (1 mile). It was studying rocks and soils inside
a crater named Endurance, about 130 meters (430 ft) wide and 22
meters (72 ft) deep. The rover entered this crater in June 2004
after careful analysis of its ability to climb back out. Inside,
Opportunity examined layer upon layer of bedrock with characteristics
similar to those of the outcrop inside the smaller crater where
it landed. This indicated a much longer duration for the watery
portion of the region’s ancient past. The rover also found some
features unlike any it had seen before, evidence of changes in the
environment over time. Whether the rovers’ unpredictable life spans
would extend only a few more days or several more months into 2005,
they have already racked up successes beyond the high expectations
set for them when the Mars Exploration Rover project began.
Mars Odyssey. The Mars Odyssey probe, launched April 7, 2001, successfully
reached Mars on October 24, 2001, after a six-month and 286-million
mile journey. Entering a highly elliptical orbit around the poles
of the Red Planet, it began to change orbit parameters by aerobraking,
reduce its ellipticity to a circular orbit at 400 km by end of January
2002. The orbiter is circling Mars for at least three years, with
the objective of conducting a detailed mineralogical analysis of
the planet's surface from space and measuring the radiation environment.
On August 25, 2004, the Mars Odyssey orbiter began working overtime
after completing a prime mission that discovered vast supplies of
frozen water, ran a safety check for future astronauts, and mapped
surface textures and minerals all over Mars, among other feats.
Odyssey's camera system obtained the most detailed complete global
maps of Mars ever, with daytime and nighttime infrared images at
a resolution of 100 meters (328 feet). The spacecraft, which has
been examining Mars in detail since February 2002 (more than a full
Mars year of about 23 Earth months) has been approved for an extended
mission through September 2006. About 85 percent of images and other
data from NASA's twin Mars rovers, Spirit and Opportunity, have
reached Earth via communications relay by Odyssey, which receives
transmissions from both rovers every day. The orbiter helped analyze
potential landing sites for the rovers and is doing the same for
NASA's Phoenix mission, scheduled to land on Mars in 2008. Plans
also call for Odyssey to aid NASA's Mars Reconnaissance Orbiter,
due to reach Mars in March 2006, by monitoring atmospheric conditions
during months when the newly arrived orbiter uses calculated dips
into the atmosphere to alter its orbit into the desired shape.
Mars Global Surveyor (MGS). MGS completed its primary mission at
the end of January 2001 and entered an extended mission. The spacecraft
has returned more data about the Red Planet than all other missions
combined. After its arrival at Mars on September 11, 1997, MGS started
a long series of aerobrake passes around the planet and, after reaching
its operational orbit early in 1999, began its mapping mission on
March 9. For the first three weeks, the mission proceeded with the
spacecraft's 1.5-m (5 ft) high-gain antenna stowed due to concerns
about the proper operation of its deployment mechanism. On March
28, 1999, the antenna was successfully deployed. Since then, MGS
has been transmitting a steady stream of high-resolution images
of Mars, which showed that the Red Planet is a world constantly
being reshaped by forces of nature including shifting sand dunes,
monster dust devils, wind storms, frosts and polar ice caps that
grow and retreat with the seasons. In 2001, it sent back its 100,000th
image of the Martian surface and, in tandem with the Hubble Space
Telescope, had a ringside seat to the largest global dust storm
on the Martian surface seen in decades. Through 2003, imagery and
transmissions continued. On May 8, it succeeded in capturing six
other celestial bodies in a single photographic frame: taking advantage
of an alignment in the orbits of Earth and Jupiter, MGS delivered
a sensational picture that included the two planets, plus our Moon
and three of Jupiter’s four Galilean satellites – Callisto, Ganymede
and Europa. In September 2004, MGS started its third mission extension
after seven years of orbiting Mars, using an innovative technique
to capture pictures even sharper than most of the more than 170,000
it has already produced. One dramatic example from the spacecraft's
Mars Orbiter Camera showed actual wheel tracks of the Mars Exploration
Rover Spirit and the rover itself. Another told scientists that
no boulders bigger than about 1 to 2 meters (3 to 7 feet) are exposed
in giant ripples created by a catastrophic flood. The new technique
involves rolling the entire spacecraft so that the camera compensates
image motion while scanning, in this way able to show details at
three times higher resolution than is normally obtained.
Earth Science In 2004,
NASA launched one Earth science satellite, the Aura.
Aura. Aura (Latin for “breeze”), launched from Vandenberg AFB on July 15 on a Delta 2 rocket, is NASA’s third major Earth Observing System (EOS) platform, joining its sister satellites Terra and Aqua, to provide global data on the state of the atmosphere, land, and oceans, as well as their interactions with solar radiation and each other. Aura’s design life is five years with an operational goal of six years. The satellite flies in formation about 15 minutes behind Aqua. During 2004, observations from Aura showed that ozone destroyed chemically in the Arctic last winter in near-record levels was restored by other atmospheric processes to near average amounts, stopping high levels of harmful ultraviolet radiation from reaching Earth's surface. The answer appeared to lie in this year's unusual Arctic atmospheric conditions, which caused polar ozone being replenished by shifted stratospheric winds, transporting ozone-rich air from Earth's middle latitudes into the Arctic polar region.
ICESat . (Ice, Cloud, and
land Elevation Satellite) is the latest Earth Observing System (EOS)
spacecraft and the benchmark mission for measuring ice sheet mass
balance, cloud and aerosol heights, as well as land topography and
vegetation characteristics. Launched on January 12, 2003, on a Delta
2 Expendable Launch Vehicle (ELV) into a near polar orbit at an
altitude of 600 km with an inclination of 94 degrees, the spacecraft
carries only one instrument,- the Geoscience Laser Altimeter System
(GLAS). Scientists trying to understand the dynamics of the Earth
are using the lasers of ICESat to measure the height of ice sheets,
glaciers, forests, rivers, clouds and atmospheric pollutants from
space with unprecedented accuracy, providing a new way of understanding
our changing planet. For example, in winter 2004, ICESat showed
thicker sea ice grouped together in its usual place near the Canadian
Arctic than it was in 2003. It also showed a larger area of thinner
ice in the Beaufort and Chukchi Seas where the summer ice cover
has been rapidly decreasing. The location and amount of ice is important
to climatologists and also ships that travel those seas.
Aqua . Aqua was launched by NASA in 2002. Formerly named EOS PM (signifying its afternoon equatorial crossing time), Aqua is part of the NASA-centered international Earth Observing System (EOS). Since May 2002, the 1750 kg (3858 lb) satellite, carrying six instruments weighing 1082 kg (2385 lb) designed to collect information on water-related activities worldwide, has been circling Earth in a polar, sun-synchronous orbit of 438 miles (705 km) altitude. During its six-year mission, Aqua is observing changes in ocean circulation and studies how clouds and surface water processes affect our climate. Aqua joined Terra, launched in 1999, and was followed by Aura in 2004 (see above).
POES-M (NOAA-M) . The operational
weather satellite POES-M
(Polar-orbiting Operational Environmental Satellites-M) was launched
from VAFB on a commercial Titan 2 rocket on June 24, 2002. The satellite,
later renamed NOAA-M, is part of the POES program, a cooperative
effort between NASA and the National Oceanic and Atmospheric Administration
(NOAA),
the United Kingdom (UK), and France. It joined the GOES-M
launched in July 2001. Both satellites, operated by NOAA, continue
to provide global coverage of numerous atmospheric and surface parameters
for weather forecasting and meteorological research.
GRACE. Launched on March 17, 2002, on a Russian Rockot carrier, the twin satellites GRACE (Gravity Recovery and Climate Experiment), named "Tom" and "Jerry", are mapping the Earth's gravity fields by taking accurate measurements of the distance between the two satellites, using GPS and a microwave ranging system. This allows making detailed measurements of Earth's gravity field, which will lead to discoveries about gravity and Earth's natural systems with possibly far-reaching benefits to society and the world's population. GRACE provides scientists from all over the world with an efficient and cost-effective way to map the Earth's gravity fields with unprecedented accuracy, yielding crucial information about the distribution and flow of mass within the Earth and its surroundings. Its science data are being used to estimate global models for the mean and time variable Earth gravity field approximately every 30 days for the 5 year lifetime of the mission. The science data from GRACE consist of the inter-satellite range change measurements, and the accelerometer, GPS and attitude measurements from each satellite. The project is a joint partnership between NASA and the German DLR (Deutsches Zentrum für Luft- und Raumfahrt).
Department of Defense space activities. United States military space organizations continued their efforts to make space a routine part of military operations across all service lines. One focus concerns plans for shifting the advanced technology base toward space in order to continue building a new foundation for more integrated air and space operations in the 21st century as space is becoming increasingly dominant in military reconnaissance, communications, warning, navigation, missile defense and weather-related areas. The use of space systems within military operations reached a new and distinct mark in 2002 for the war on terrorism and operations in Afghanistan and subsequently in Iraq in 2003 and 2004. The increased use of satellites for communications, observations, and – through the Global Positioning System (GPS) – navigation and high-precision weapons targeting was and is of decisive importance for the military command structure. Orbiting assets ably demonstrated during the Iraq conflict and thereafter that space-based intelligence, surveillance, communications, weather, missile warning and navigation tools give commanders great advantages and leverage for each of the military services.
In 2004, there were five military space launches (2003: 11), carrying five payloads: one Titan 4B/IUS vehicle from Cape Canaveral, Florida, with the DSP-022 early warning satellite, three Delta 2s with GPS navigation satellites, and one Atlas 2 AS with an NRO communications satellite.
Commercial space activities. In 2004, commercial space activities in the United States exhibited a sluggish increase over prior years, after the 2001/2002 downturn in the communications space market caused by failures of satellite constellations for mobile telephony and a slight recovery in 2003.
In addition to the financial problems, some difficulties remained due to the export restrictions imposed to the US industry on sensitive technologies. In general, commercial ventures continue to play a relatively minor role in US space activities, about as in 2001 (50%), but more than the 26% in 2002 and 31% in 2003, of commercial satellites and associated launch services worldwide.
Of the 19 total launch attempts by the United States in 2004 (26 in 2003), ten were commercial missions (NASA: 4; military: 5). In the launch services area, Boeing sold seven Delta-2 vehicles, while competitor ILS/Lockheed Martin flew four Atlas 2AS and one Atlas 3B (with Russian engines). Both companies also had successful launches of their next-generation EELV (evolved expendable launch vehicle) rockets, viz., Lockheed Martin with the fourth Atlas 5/Centaur (comsat AMC-16), and Boeing with the first Delta 4H (heavy) launcher (Demosat, plus imaging test satellites 3CS-1 and 3CS-2), while the partnership of Boeing, RSC-Energia (Russia, 25% share), NPO Yushnoye (Ukraine) and Kvaerner Group (Norway) successfully launched three Russian Zenit 3SL rockets carrying Brazil’s Estrela do Sul (Telstar 14), US DirecTV-7S and China’s Telstar 18 comsats from the Odyssey sea launch platform floating at the Equator (first launch 1999).
2004, however, was a historic year for privately funded personal
space travel. On June 21, SpaceShipOne,
a joint venture between Vulcan and the Scaled Composites Company
of Burt Rutan became the first commercial spacecraft when it rocketed
beyond the 100-km threshold of space, launched from its piloted
mother ship/airplane White Knight, reaching 100,124 m (328,491 ft)
with pilot Mike Melvill. After this test flight, on September 29
SpaceShipOne made the first of the two flights for the Ansari X-Prize
of $10-million, again piloted by Mike Melvill (who had to control
over 25 unscheduled rolls) plus ballast representing a second passenger
to 102.9 km, followed on October 4 by the second flight, with Brian
Binnie at the helm, to 112 km. Already in 2003 the mother ship/airplane
White Knight
and SpaceShipOne had made their first flight, on May 20 to 15 km
(nearly 50,000 ft), both remaining joined. The first gliding flight
of the latter then followed on August 7, after separation from the
carrier aircraft at 14.3 km (47,000 ft).
Bibliography Aviation Week & Space Technology
(AW&ST, various ‘04 issues); Aerospace Daily (various
‘04 issues), SPACE NEWS (various ‘04 issues); AIAA
AEROSPACE AMERICA, November 2004 issue; NASA Public Affairs
Office News Releases ’04; ESA Press Releases '04;
various Internet sites.
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