WASHINGTON — While SpaceX struggles to determine the cause of a failure of its Falcon 9 rocket, NASA managers and other users of the International Space Station say the loss of the cargo on the Dragon spacecraft on that rocket should not have a major effect on station operations.
The Falcon 9 v1.1 lifted off from Cape Canaveral Air Force Station in Florida at 10:21 a.m. Eastern time June 28, carrying a Dragon spacecraft with more than 2 tons of cargo for the ISS. SpaceX reported no technical issues during the countdown, and weather conditions were excellent at the time of liftoff.
The first evidence of a problem could be seen two minutes and 19 seconds after liftoff, as a white cloud expanded from the Falcon 9’s upper stage even as the rocket’s first stage engines continued to fire. The rocket was soon enveloped in the cloud and, within 10 seconds, broke apart.
More than a week later, the cause of the failure, the first in 19 Falcon 9 launches, continued to elude the company. The company has released few details about the investigation, but SpaceX Chief Executive Elon Musk said July 7 the failure did not appear to have a straightforward cause, and that the data the company had to analyze were difficult to interpret.
“Whatever happened is clearly not a sort of simple, straightforward thing,” he said in his most extensive public comments to date on the launch failure in an appearance at the ISS Research and Development Conference in Boston. “There’s still no clear theory that fits with all the data.”
Musk reiterated earlier statements that linked the failure to an “overpressure event” in the liquid oxygen tank in the upper stage of the Falcon 9. What caused that overpressure event, though, remains uncertain.
Musk said the company was working on a “super-detailed” timeline of the failure, accurate to millisecond, and left open the possibility that some of the data might be corrupted or otherwise in error. “We’re determining if some of the data is measurement error of some kind, or whether there’s actually a theory that matches” the data on hand, he said.
Because the launch was commercially licensed by the Federal Aviation Administration, SpaceX is leading the investigation into failure, with participation from NASA, the FAA and the National Transportation Safety Board (NTSB). “The interaction with NASA has been great so far,” Musk said.
At a hearing of the House Science space subcommittee July 10, William Gerstenmaier, NASA associate administrator for human exploration and operations, said that while SpaceX is leading the investigation, decisions
to rule out potential causes require the concurrence of the other agencies involved.
“We need to be careful that we don’t jump to conclusions,” he said. Investigators have developed a “fault tree” that includes all potential causes of the failure, which he said are then systematically investigated, item by item. “All three entities — NASA, the FAA and NTSB — and SpaceX all have to agree that this item is closed and not contributing to this accident. It’s by consensus,” he said.
Gerstenmaier said that because SpaceX builds most components of the Falcon 9 in-house, it can move quickly to test hardware that might have played a role in the failure, sometimes separate from the main investigation. “They’re actually off in the laboratory doing some stress tests on some components that may contribute, as a parallel activity to this more methodical process.”
Mitigating ISS Concerns
The Dragon lost on the Falcon 9 failure was the seventh mission under SpaceX’s Commercial Resupply Services contract with NASA. It carried 1,867 kilograms of pressurized cargo intended for the ISS, a total that increased to 1,952 kilograms when including the weight of the cargo’s packaging. That total included 676 kilograms of crew supplies, 461 kilograms of hardware for the ISS, and 529 kilograms of scientific investigations.
The largest, and perhaps most valuable, item lost on the Dragon was an International Docking Adapter (IDA), a 526-kilogram item transported as unpressurized cargo in the “trunk” section of the Dragon spacecraft. The IDA, one of two built by NASA, would have been attached to the station to serve as a docking port for future commercial crew vehicles.
Gerstenmaier said at the July 10 hearing that the second IDA is built and awaiting launch when commercial cargo missions resume. He added the agency is planning to build a replacement adapter using spare parts, which could be ready to install on the station before commercial crew flights begin. Only one IDA, though, is needed to accommodate commercial crew vehicles.
He added that NASA had plans to deal with two other major pieces of hardware lost on the Dragon, a spacesuit and water filtration unit. “I think we’ve mitigated all three of the concerns,” he said.
Gerstenmaier acknowledged that the recent string of cargo mission failures will have a cost for NASA. Some performance goals for space station research will not be met this year, he said, because of lost cargo missions and a delay in launching a new crew after the April Progress failure. He estimated the value of the NASA cargo lost in the SpaceX accident at approximately $110 million.
Other items on the Dragon included dozens of experiments, some created by students, as well as eight cubesats built by San Francisco-based Earth imaging company Planet Labs that would have been deployed from the airlock on the station’s Kibo module.
For Planet Labs, the failure was the second time the company lost satellites on an ISS cargo mission: 26 of its Dove satellites were on an Orbital Sciences Corp. Cygnus spacecraft destroyed in an October 2014 launch failure. “This is a hard day for Planet Labs but we’ve experienced a launch failure before, and statistically, we will again,” Planet Labs Chief Executive Will Marshall said in a June 28 statement.
NASA emphasized immediately after the accident that despite the loss of supplies on the Dragon and two previous failures of cargo missions, the station’s crew was not in danger of running low of food or water. At the time of the failure, those supplies were expected to last through October. A Progress cargo spacecraft that docked to the station July 5 carried about one month’s worth of additional supplies.
Besides the Progress, a Japanese H-2 Transfer Vehicle (HTV) is scheduled to launch Aug. 16 to the ISS. NASA is only planning to make minor changes to the cargo it is flying on that vehicle, NASA ISS program manager Michael Suffredini said July 7 at the Boston conference.
“We did make changes to the manifest, but it’s important to note that the only research change that we made to that manifest is to take off some hardware to support research that’s going to occur on SpaceX-9,” he said, referring to a future SpaceX cargo mission postponed by the failure.
Orbital ATK is planning to return Cygnus to flight in December, launching the cargo spacecraft on a United Launch Alliance Atlas 5 while the company works on incorporating a new first-stage engine in its Antares launch vehicle. Gerstenmaier said immediately after the SpaceX failure that the mission could potentially be moved up to October, depending on launch manifests and space station activity.
Company officials now say the launch is unlikely to be moved up, primarily because the successful Progress mission has eased concerns about station supply levels. “The return to flight is going well,” Frank Culbertson, president of the space systems group at Orbital ATK, said in a conference presentation July 8. “Things are on track for a launch Dec. 3.”
‘Business as usual’
Other users of the ISS have said they are not concerned about the station’s status despite the SpaceX failure. “Right now, it’s business as usual,” said Greg Johnson, the president of the Center for the Advancement of Science in Space, the nonprofit organization that manages the portions of the ISS designated as a U.S. national laboratory, July 8. He said there was “not yet” any sign of pushback from current or potential users of the station.
Amir Blachman, principal of the Space Angels Network, a group of individual investors who fund early stage space companies, said July 7 there was no evidence of concern among the group’s members about investing in space companies, including those who plan to use the ISS, as a result of the SpaceX launch failure.
“We have 60 investors in our network right now. I did not receive a single phone call or email” after the accident, he said. “No one’s talked about pulling funding or getting off of the manifest.”
SpaceX has not indicated when it will resume Falcon 9 launches, including missions to the ISS. Musk, in his comments at the Boston conference, indirectly suggested the Falcon 9 could return to flight later this year by discussing the company’s efforts to land the rocket’s first stage on a ship in the Atlantic Ocean.
“Hopefully later this year we’ll be able to do that,” he said.