SpaceX: Dragon testing will determine launch schedule
BY STEPHEN CLARK
Posted: August 20, 2010
SpaceX delivered the first space-worthy Dragon capsule to Florida in early August as engineers dropped a replica of the craft in the Pacific Ocean to simulate the ship's return from orbit.
The milestone followed deliveries of the Falcon 9 rocket's first and second stages on July 15 and July 31.
Elon Musk, SpaceX's founder and CEO, told Spaceflight Now last week that launch of the second Falcon 9 rocket is still a "few months away" as engineers get used to working with toxic hypergolic propellants and processing a functional Dragon capsule.
The first Falcon 9 mission in June launched a stripped-down version of the Dragon spacecraft without an operating propulsion system or its advanced avionics.
Musk said the company is being "super careful" in preparations for the upcoming launch, which was previously targeted for late September.
Officials won't discuss target launch dates due to uncertainties in preparation schedules, especially for a first-time vehicle like Dragon.
"Dragon will launch as soon as it is ready, but it is unlikely to be September," Musk told Spaceflight Now on Friday.
The drop test was to validate the Dragon's parachute deployment systems and recovery operations. The company said the test was 100 percent successful.
After the helicopter released the capsule at an altitude of 14,000 feet, the craft deployed two drogue parachutes for stability, then three orange and white main parachutes unfurled to a diameter of 116 feet each.
The dummy capsule was recovered by boat and returned to shore, according to SpaceX.
The Dragon's chutes are supposed to slow the craft to a gentle splashdown between 16 and 18 feet per second, or approximately 12 mph. Apollo command modules splashed down at a velocity of about 19 mph.
Even if one parachute fails, SpaceX says the Dragon could still make a safe landing.
Engineers designed the spacecraft to eventually transport astronauts to orbit, and SpaceX is a leading contender for snagging another NASA deal to provide commercial crew services in the next few years.
During the Dragon's orbital shakedown later this year, the ship will cruise around Earth between one and three times, fire its Draco maneuvering thrusters and fall into the Pacific Ocean somewhere off the coast of Los Angeles near the Channel Islands.
The flight could last from less than two hours to five hours, depending on SpaceX's final decision on its duration.
In a July interview with Spaceflight Now, Musk said the Dragon demonstration mission is designed to achieve a range of test objectives.
"Can it go up there, can it maneuver around, does it maintain integrity, maintain communications, can it re-enter? Re-entry and coming back in one piece is really difficult," Musk said. "How does the main heat shield function, the backshell, do the parachutes deploy? When it lands in the water, what kind of loads does it experience?"
"The main things we're going to be testing are the Draco engines," Musk said.
The Dragon uses 18 of the hydrazine-fueled thrusters to change its orientation in orbit, raise and lower its altitude, and slow its speed for re-entry at the end of the mission.
"This is about a 100-pound thrust engine," Musk said. "It's capable of very short pulse firings as well as long-duration firings. It has dual use as both attitude control maneuvering and orbit translation."
Communications and navigation instrumentation will also be put to the test.
"We'll also be testing the integrity of the core pressure vessel for Dragon, including the windows and other things which are precursors for flying crew," Musk said.
"Another big one is de-orbit and re-entry, which will test the main heat shield and the backshell," Musk said.
The Dragon's blunt end is covered in a carbon-based ablator called PICA-X to shield the spacecraft from temperatures as high as 3,600 degrees Fahrenheit.
The PICA-X formula is an improvement on the heat shield used by NASA's robotic Stardust probe that returned samples from the dust cloud of a comet. SpaceX developed the upgraded PICA-X material with help from NASA's Jet Propulsion Laboratory and Ames Research Center, where it was tested inside an arc jet facility to check its strength when exposed to high heat.
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