Two software bugs after starting aThe crew's ship during a non-flown test flight last December, one of which prevented scheduled docking with the International Space Station, could have resulted in catastrophic failures if it hadn't been caught and corrected in time, NASA said on Friday.
An independent review panel "found that despite critical security measures, the two critical software bugs were not discovered before the flight," the agency said. "In both cases, intervention on the ground prevented the vehicle from being lost."
In a conference call with reporters, Douglas Loverro, director of space operations at NASA headquarters, said the problems uncovered by the investigators would go beyond the peculiarities of the software flaw and an unexpected communication error that initially prevented air traffic controllers from commanding the spacecraft.
"To put it bluntly, the problem we're dealing with is that we have numerous process errors in the Starliner software design, development and testing cycle," he said. The errors themselves "are probably just symptoms, they are not the real problem. The real problem is that we have had numerous process outbreaks" that allowed the errors to slip through.
The Starliner software consists of a million lines of code and "as we continue, we will focus on how we can convince ourselves that all of the software that we have delivered is not just the" two routines affected by these problems have been fixed. "
"Our NASA oversight was inadequate," concluded Loverro. "This is obvious and we recognize it. And I think that is good learning for us. The independent review team not only had recommendations for Boeing, it also has recommendations for us and we will take all of these hearts."
Neither Loverro, NASA administrator Jim Bridenstine, nor Boeing Starliner project manager John Mulholland would speculate whether a second test flight without a pilot or without a pilot could be ordered this year. Such decisions are only made after the security check at the end of the month.
"We are not currently speculating on a specific launch date," said Mulholland. "We have to fully understand the scope of the corrective action and implement it in a work plan. Once we have defined this scope, we can evaluate a specific starting goal."
The Boeing CST-100 was StarlinerThe aim of the flight was to put the commercial crew ship through its paces on the top of a United Launch Alliance Atlas 5 rocket, from launch to rendezvous and docking with the space station to reentry and hosing to clear the capsule for a piloted test flight.
The Atlas 5 brought the Starliner to a suborbital trajectory as planned. After being released from the second stage of the Centaur missile, the spaceship was to fire its own engines to put the spaceship in a safe orbit. However, the critical orbit rocket bombardment never took place and the Starliner continued to travel on a trajectory that would have resulted in catastrophic unplanned reentry without rapid corrective action.
After struggling with communication problems, the engineers finally managed to regain control and put the spacecraft in a safe orbit. Until then, however, too much fuel had been wasted to advance a planned rendezvous with the International Space Station. Instead, the air traffic controllers focused on doing as many other tests as possible before landing the ship in New Mexico two days later.
The Starliner's failure to launch the orbit fire was attributed to software that incorrectly set the spacecraft's internal clocks based on data retrieved from the Atlas 5 flight control system. The Starliner code should have retrieved the time during the terminal countdown after the Atlas 5 clocks were set to start exactly.
Instead, the Starliner computer retrieved the time that was used during an earlier countdown sequence. As a result, its timer was 11 hours away from actual time. This, in turn, has delayed the timing of post-launch events, including the fire when placed in orbit.
After this problem was resolved, the engineers started checking other critical software sequences as a precaution and discovered another problem. The engine ignition control software needed to safely drop the Starliner service module immediately before re-entry was incorrectly configured and set to the wrong flight phase.
If the problem had not been found and resolved, the cylindrical service module's engines would have fired in the wrong order, driven the crew module back and possibly caused a fall, or even damaged the ship's heat shield.
A detailed analysis has not yet been carried out at this point. "Nothing good can happen if these two spaceships collide again," said Jim Chilton, senior vice president of Boeing Space and Launch.
The timing problem was well known during the Starliner test flight, but the problem with the service module only came to light at a meeting of NASA's aerospace advisory board on Thursday, which was often on social media for more information and "Transparency" was asked, detailed NASA's Commercial Crew program.
NASA replied on Friday with an online statement and a media conference call.
"It is very unusual for NASA to hold a press conference on the results of the investigation while the investigation is ongoing," said Bridenstine. "But for the sake of transparency and some things I saw online yesterday, I wanted to make sure everyone knew where we were in the investigation."
Engineers are still investigating what caused the communication disruptions that initially prevented air traffic controllers from quickly resolving the timing problem. As it turns out, Mulholland says high background noise, possibly from cell phone towers, may have played a role.
In any case, "software errors, especially in complex code for spacecraft, are not unexpected," says NASA's statement. "However, there were numerous cases in which the quality processes of the Boeing software should or could have revealed the defects.
"Because of these defects in the design, code, and testing of the software, systemic corrective actions are required. The team has already identified a solid set of 11 high-priority corrective actions. More will be identified as the team completes its additional work." , "
Mulholland said: "Nobody is more disappointed with the problems we uncovered … than the Starliner team. But for one person, they are determined to work with NASA and IRT to resolve these problems and return safely to flight. "
Since the space shuttle's departure in 2011, NASA has been forced to purchase seats on board the Russian Soyuz spacecraft to transport U.S. astronauts and partner astronauts to and from the International Space Station.
To end Russia's sole dependency on transport to and from the space station, NASA announced in 2014 that Boeing and SpaceX will provide $ 6.8 billion for the development of independent space taxis, the first new U.S. manned ones Spaceships since the 1970s.
As part of a $ 2.6 billion contract, SpaceX is building a manned version of its Dragon cargo ship that will fly into orbit on the company's Falcon 9 rocket. Boeing's Starliner is being developed under a $ 4.2 billion contract.
SpaceX has performed successfullyin March 2019, but suffered a severe setback the following April when the same Crew Dragon capsule was destroyed during a ground test. The California-based rocket maker has recovered from this incident and successfully completed it Test in January.
It is generally expected that SpaceX will launch a Crew Dragon with two NASA astronauts – Douglas Hurley and Robert Behnken – this spring.
The Boeing unmanned test flight in December was only partially successful due to the two software errors and the communication disruption. It is not yet known whether NASA will order a second pilot-free test flight or whether Boeing will be approved to drive a piloted mission after corrective measures have been implemented.
"It is too early to finally identify the causes and corrective actions for the Starliner system," said NASA. "We expect these results in late February, as was our original plan.
"Above all, we want to make sure that these necessary steps are fully understood before the future flight plan is determined. In addition to examining anomalies, NASA continues to review the data collected during the flight test to determine this future plan. NASA expects that a decision on this review will be completed in the next few weeks. "