The last twelve months have truly been a rollercoaster ride for Space Exploration Technologies (SpaceX)—the Hawthorne, Calif., company, led by entrepreneur Elon Musk—whose Falcon 9 rocket and unmanned Dragon cargo craft thundered into the public consciousness in both a positive and negative light. In May 2012, Dragon triumphantly flew a demonstration flight to the International Space Station, becoming the first commercial craft ever to have a spacecraft be berthed there, and in October its maiden Commercial Resupply Services (CRS-1) mission under SpaceX’s $1.6 billion contract with NASA was successfully concluded. That success, however, was tempered by an engine-out anomaly, just 80 seconds after launch, which spelled disaster for a small Orbcomm piggyback satellite. Now, almost five months later, another Falcon 9 and fully-loaded Dragon stand ready at Space Launch Complex 40 (SLC-40) at Cape Canaveral Air Force Station in Florida—primed to restore an otherwise-proud reputation.
Liftoff of the CRS-2 mission is currently scheduled for 10:10 a.m. EDT, March 1, beginning an ambitious four-week voyage which will see the first use of Dragon’s unpressurized “Trunk” section to carry equipment and supplies. The whole Dragon measures 19.3 feet long and 12 feet wide. Some 1,490 pounds of cargo will be transported to the ISS, of which a little more than half is dedicated to ongoing scientific research. This includes a pair of General Laboratory Active Cryogenic ISS Experiment Refrigerators (GLACIER)—one powered and the other unpowered—to support multiple biological samples with thermal-control requirements between -160°C and +4°C. A spare electronics unit for one of the ISS’s Minus-Eighty Laboratory Freezers for ISS (MELFI), a Carbon Dioxide Removal Assembly (CDRA) bed, and crew provisions will also be aboard.
Attached to Dragon’s external Trunk will be two Heat Rejection Subsystem Grapple Fixtures (HRSGFs), which will provide grapple fixtures to enable the station’s Canadarm2 manipulator to interface with ISS radiators, should the need arise to repair or replace them. Shortly after CRS-2 arrives at the space station March 2—barely a day after rising from the United States’ East Coast—the Trunk external payloads will be robotically removed by Canadarm2, under the control of U.S. Operating Segment (USOS) crewmen Kevin Ford and Tom Marshburn. They will be temporarily housed on the Mobile Base System of the football-field-sized truss structure, to await installation on the S-1 and P-1 trusses during an EVA by Expedition 36 astronauts Chris Cassidy and Luca Parmitano in June–July.
Dragon’s return to Earth—and a splashdown in the waters of the Pacific Ocean, off the coast of southern California—is presently scheduled for March 25. The spacecraft’s recoverable re-entry capsule will bring more than 2,300 pounds of equipment and materials back to Earth, including a GLACIER freezer and several failed environmental control system components. In doing so, Dragon will demonstrate yet again its capacity to pick up some of the load from the now-retired space shuttle fleet, providing the United States with a home-grown upmass/downmass capability to and from the ISS.
The return of Dragon will come ten days after the return of Expedition 34’s Kevin Ford, Oleg Novitsky, and Yevgeni Tarelkin, who are due to land on the steppe of Kazakhstan March 15, concluding a five-month voyage which began last October. In the coming days, Ford will hand over command of the multi-national outpost to its first Canadian skipper, Chris Hadfield, who will lead the ISS into the summer of 2013.
Friday’s launch of CRS-2—also known as “SpX-2” within the ISS Program, in recognition of SpaceX—will undoubtedly excite the company’s growing fanbase, following the anomalous rise to orbit of the previous Falcon 9 last October. One of the booster’s nine Merlin-1C engines on its first stage suffered a sudden pressure loss and an automatic shutdown command was issued; the other eight engines burned for an additional 30 seconds to compensate for the reduced thrust, thereby vindicating SpaceX’s claims about the Falcon’s ability to handle “engine-out” situations. “As designed, the flight computer then recomputed a new ascent profile in real time to reach the target orbit,” explained CEO Elon Musk in October, “which is why the burn times were a bit longer.”
This offered small comfort for a second-generation Orbcomm satellite, which was hitching a “piggyback” ride into orbit. Original plans called for the Falcon 9’s second stage to execute a short burn of its single Merlin-1C engine to raise its orbit and eject the Orbcomm, but since this burn was dependent upon the stage being sufficiently healthy it could not be performed. Consequently, the Orbcomm was deployed into an untenable, far-lower-than-intended 125 x 200-mile orbit, and it burned up in the atmosphere within a matter of days.
Following an investigation process into the engine-out anomaly, the Falcon 9 for CRS-2 arrived at Cape Canaveral Air Force Station in late November and underwent a successful, two-minute static test-firing at SLC-40 yesterday (Monday, Feb. 25), as this article was being prepared. The static test got underway with the ignition of all nine Merlin-1C engines at 1:30 pm EST and appeared to proceed without incident. At the end of the test, shutdown commands were transmitted to all engines and standard safing procedures were executed. Friday’s launch will be preceded by a flurry of activity, due to culminate with the loading of rocket-grade kerosene (RP-1) and liquid oxygen aboard the Falcon about two hours ahead of liftoff. The vehicle will be transferred to internal power at T-4 minutes, after which the flight termination system—used to destroy the launch vehicle in the event of off-nominal events during ascent—will be armed and oxidizer levels topped-off. One minute before launch, SLC-40’s “Niagara” deluge system will flood the pad surface with 30,000 gallons of water to suppress acoustic waves radiating from the Merlin engine plumes.
Launching with a Dragon for the first time in the daylight hours, the Falcon’s nine engines will ignite, producing a combined 1.1 million pounds of thrust and providing the impulse for the first three minutes of the climb to orbit. Two of the engines will shut down at T+170 seconds to reduce the acceleration, with the other seven shutting down about 10 seconds later. By this stage, the Falcon will be at an altitude of 50 miles. After the burn-out and separation of the first stage, the single Merlin-1C of the second stage will ignite. It will fire for a total of 345 seconds, delivering Dragon into a preliminary orbit and setting it up for a rendezvous with the ISS, which is scheduled to take place the following day.
Following its return to the waters of the Pacific, 300 miles off Baja California, it appears that subsequent Dragon missions will take place at roughly six-month intervals, with CRS-3 tentatively scheduled to fly September 30 and CRS-4 in early April 2014. NASA’s contract with SpaceX calls for the company to stage 12 missions in total and deliver around 44,000 pounds of payload to the ISS.Missions » ISS » COTS » CRS-2 »