WASHINGTON — SpaceX has postponed the scheduled Dec. 19 launch of an international space station cargo mission until early January, as a technical issue with the Falcon 9 rocket creates a domino effect of other delays.
In a statement issued Dec. 18, SpaceX said that a recent static fire test of the Falcon 9, where the vehicle’s nine first stage engines are briefly fired on the launch pad, encountered problems that led the company to repeat that test and thus delay the launch.
“While the recent static fire test accomplished nearly all of our goals, the test did not run the full duration,” the company said in its statement. “The data suggests we could push forward without a second attempt, but out of an abundance of caution, we are opting to execute a second static fire test prior to launch.”
The delay created by the rescheduled static fire test created further delays “due to the holidays and other restrictions,” SpaceX said in the statement. Company spokesman John Taylor declined to elaborate on what the additional restrictions are.
One issue that both SpaceX and NASA acknowledged contributed to the delay is the space station’s high “beta angle,” a measure of how much of each orbit the ISS is in sunlight. The ISS will be in nearly constant sunlight from Dec. 28 to Jan. 7, NASA said in a statement. “During this time, there are thermal and operational constraints that prohibit Dragon from berthing to the station,” the agency said.
SpaceX and NASA have rescheduled the launch for Jan. 6 at 6:18 am EST, with a backup launch date of Jan. 7. A launch on Jan. 6 would allow the Dragon to arrive at the ISS on the morning of Jan. 8.
The launch is the fifth of twelve Dragon missions to the ISS SpaceX is under contract to perform as part of its Commercial Resupply Services (CRS) contract with NASA. Dragon is scheduled to deliver 2,395 kilograms of cargo to the ISS, including supplies, hardware, and experiments. It will return about four weeks later with 1,662 kilograms of equipment from the station.
SpaceX also plans to use this launch to test the ability to recover the Falcon 9’s first stage. On several recent launches, SpaceX has attempted to “land” the first stage on the ocean. The stages touched down on the ocean surface, but toppled over and broke apart immediately afterwards.
For this launch, SpaceX has developed what it calls an “autonomous spaceport drone ship,” about 90 meters long and 50 meters wide, that will be stationed in the Atlantic Ocean downrange of the Cape Canaveral, Florida, launch site. The company will attempt to land the stage on the ship, using four fins deployed during reentry to improve landing precision.
In a Dec. 16 statement describing their stage recovery plans, the company cautioned that it was an experiment. “Though the probability of success on this test is low, we expect to gather critical data to support future landing testing,” the company said.
With this launch rescheduled for January, SpaceX will finish 2014 with six Falcon 9 launches, less than the ten that company officials projected early in the year. SpaceX has not announced a launch schedule for 2015, but now has two launches planned for January: in addition to the rescheduled CRS mission, a Falcon 9 is scheduled to launch the Deep Space Climate Observatory (DSCOVR) spacecraft for the National Oceanic and Atmospheric Administration on Jan. 23 from Cape Canaveral.