On April 3, 1993, the DC-X, completed ahead of schedule (an unusual occurrence in aerospace history), rolled out of its hangar at the McDonnell Douglas Huntington Beach, California, plant. Maj. Jess Sponable, who had succeeded Pat Ladner as SSRT (Single Stage Rocket Technology) Program Manager, oversaw DC-X vehicle testing at the White Sands Missile Range, near Las Cruces, New Mexico. Over the following months, SSRT Program and McDonnell Douglas personnel conducted hot test firings of the propulsion system in preparation for the first test flight, which was a short "bunny hop" that took place on August 18, 1993, at 4:43pm MDT, at the White Sands launch site. The DC-X rose to a height of 150 feet (46 meters), moved sideways about 350 feet (100 meters), then descended softly during a 59-second flight that verified the vehicle's flight control systems and vertical landing capabilities. The Delta Clipper team was cautious about this first flight and limited the fanfare.

The second DC-X flight, however, received wide media attention. At 11:12am MDT, the Delta Clipper attained a height of 300 feet (92 meters) during a 66-second flight that tested the ascent and landing mode controls. During a third flight, at 10:30am MDT on September 30, 1993, which lasted 72 seconds, the DC-X reached a height of 370 meters, executed a 180-degree roll, and collected aerostability data.

In addition to these successful test flights that validated the SSRT Program concepts, Congress approved funding for the next program stage, Phase III, design and construction of a larger, more technologically ambitious flight vehicle, the DC-Y. Finding money for Phase III in the fiscal 1994 budget had not been easy, because Congress was looking for programs to pare down. Nonetheless, in September 1993, the House Armed Services Committee authorized $79.88 million in fiscal 1994 to begin development of the SSRT Phase III vehicle. The Senate subsequently passed the Domenici-Bingaman Amendment to the Pentagon Authorization Bill by a vote of 66 to 33, thereby providing funding for the SSRT program.

Budgetary approval of the Phase III DC-Y vehicle appeared to signal Congressional endorsement of the single-stage-to-orbit concept. Similarly positive signals had come from the nation's space agency that summer. As we saw in the Fact Sheet 2 section "The Advanced Technology Team Study," the July 1993 results of NASA's Access to Space Study favored single-stage-to-orbit reusable launch vehicles over the Shuttle and expendable launchers. NASA's apparent endorsement of a rocket-powered single-stage-to-orbit reusable launch vehicle was a dramatic departure for the space agency, which had abandoned the quest for full reusability during the design of the Space Shuttle in the 1970s. The arguments provided by the Access to Space Study Option 3 team in favor of a rocket-powered single-stage-to-orbit reusable launcher, as well as the type of technology development program proposed, are, therefore, of some interest, as they swayed Dan Goldin, NASA Administrator, and other top space agency officials.

Both the July 1993 Option 3 report and the January 1994 Summary Report projected how a full-scale single-stage-to-orbit reusable vehicle would fit into the country's future launch fleet. The July 1993 Option 3 report stated that the single-stage-to-orbit rocket would "accommodate Space Station resupply" and put into orbit NASA, Pentagon, and commercial payloads weighing up to 20,000 or even 25,000 pounds. Until this single-stage-to-orbit vehicle became available, though, an "interim expendable launch vehicle program," the upgrading of the existing fleet of Delta, Atlas, and Titan launchers, would take place in calendar years 2000 to 2008. Later, the reusable single-stage-to-orbit vehicle would capture "Delta, Atlas, and Shuttle missions at approximately 15% of the current combined annual operating costs of these systems."

The Summary Report echoed the July 1993 Option 3 report on the need for an interim launcher strategy, until the time that a single-stage-to-orbit vehicle was available. Both "the current expendable launch vehicles and the Space Shuttle," the Summary Report stated, "will have to be operated for at least another 10 to 15 years before new launch vehicles can be available." Eventually, though, "the preferred single-stage-to-orbit rocket alternative" would be "sized so as to accommodate all payloads in the mission model," in order "to avoid the need to carry current Titan expendable launch vehicles in parallel." As for the NASP program, which had not yet been canceled, the Summary Report recommended that the NASP technology program "should continue independently of any decision to proceed with development of a nearer-term low-Earth orbit launch system." The single-stage-to-orbit rocket technology development program was not going to pose a political or budgetary threat any existing NASA program.

The Access to Space Summary Report, released in January 1994, further drove home the arguments in favor of a single-stage-to-orbit vehicle over both the upgraded Shuttle and improved expendable launchers. The Summary Report concluded that a new vehicle would reduce costs and increase safety more than any "number of beneficial improvements to the Shuttle system." In terms of design, development, test, and evaluation (DDT&E) costs, the Option 3 vehicle was "more consistent with projected near-term budget availability." The budget investment in DDT&E was smaller, but more near-term, for the Option 2 architecture (improved expendable launchers) using current technology new launch vehicles and carriers. Although the Option 3 vehicle architectures required larger design, development, test, and evaluation outlays, the start of their development was delayed 4 to 5 years as a result of the necessity of maturing and demonstrating the required technologies. Thus, Option 3 was more consistent with projected near-term budget availability.

The "most attractive option," the Summary Report concluded was a "new advanced technology single-stage-to-orbit pure-rocket launch vehicle." It would feature reduced annual costs, as well as total "life-cycle" costs. In addition, development of a single-stage-to-orbit rocket would bring about new technologies "with dual-use in industry (such as composite vehicle structures for cars and airplanes)," not to mention that its development "would place the U.S. in an extremely advantageous position with respect to international competition, and would leapfrog the U.S. into a next-generation launch capability."

The Option 3 July 1993 report and the Access to Space Summary Report did not recommend proceeding immediately to the selection and development of a single-stage-to-orbit rocket architecture. Instead, the July 1993 report advised initiating "comprehensive vehicle design trade studies" concurrent with "an associated technology maturation program … utiliz[ing] a fast-track management approach that would involve the development of flight experiments and experimental, or 'X', vehicles." Thus, they envisioned a parallel ground and flight technology development and testing program.

The later Summary Report also recommended against proceeding immediately to design and development of the advanced technology single-stage-to-orbit rocket launch vehicle, and emphasized budgetary constraints. "Though it is possible to start development right away and perform technology maturation and demonstration concurrently," the Summary Report warned, "such an approach carries with it greater technical, schedule, and cost risks. Further, it would immediately require large budgets, precluding the 4 to 5 years of relatively modest budgetary investment. However, once the required technologies are matured and demonstrated at the subsystem/system level in the pertinent environment, the perceived risk is much reduced and should be manageable."