“We’re moving into a new era,” Jim Bridenstine said 19 Dec 2019. “We are going to launch American astronauts, on American rockets, from American soil for the first time since the retirement of the space shuttles.”
animation and objectivesBoeing Starliner made a smooth launch on 20 Dec, 2019. But failed to reach ISS. It was found due to Mission Elapsed Timer error.
The spacecraft’s mission elapsed timer, which is set by communicating with its Atlas 5 rocket prior to liftoff, was off by 11 hours. That caused the spacecraft to think it was on the wrong phase (ISS Station proximity ops) of its mission after separation from the rocket’s upper stage, triggering thruster firings that used excessive amounts of fuel until ground controllers could take over and turn off the thrusters.
After being released by the rocket(MECO), Starliner was supposed to use its Orbital Maneuvering and Attitude Control engines to provide the thrust needed to reach a stable orbit(1) and begin the process of catching up to the International Space Station. But that did not happen.
During a post-launch news conference, NASA Administrator Jim Bridenstine explained that the mission elapsed timing system had an error in it, with the net effect that the spacecraft thought it was performing an orbital insertion burn, when in fact it was not.
This led to it fire its reaction control system (RCS) thrusters to keep what it is believed to be the correct attitude.
The on-board computer then expended a significant amount of propellant to maintain a precise attitude, thinking it had reached 400km orbit.
Efforts to override the automated flight
When ground-based controllers realized the problem, they immediately sent a command to begin the orbital insertion burn, but due to a communications problem—which could have been a gap in coverage of NASA's Tracking and Data Relay Satellite System or some spacecraft error—those commands were not received right away by Starliner. So it continued to expend fuel to maintain a precise attitude.
By the time the commands got through, Starliner had expended too much fuel to make a safe rendezvous and docking with the International Space Station, the primary goal of this test flight.
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Starliner was stabilised in a much lower 187 x 222km orbit, and rescheduled to have earlier return to Earth.
The re-entry on 22 Dec was successful, landing in White Sands missile range.
in video, 44:50, Jim Chilton SVP of Boeing Space & Launch, replied the timer was 11 hours off.
It seems there is a missing coverage in integration test in between ULA and Boeing. The MET timing data from Atlas Rocket is not correctly converted and input to flight computers of Starliner . Keep in mind that Starliner is designed to be "launch vehicle agnostic". This is crucial that Boeing is designed to be compatible to various first stage boosters, be it Atlas V, Delta IV, Falcon 9, Vulcan or others.
This expressed the pain of NASA transition from a wholly government owned organisation to a commercial crew program. The mindset needs to shift to subcontracting, and more clear R&R.
6 Feb 2020 update:
- Regarding the Mission Elapsed Timer anomaly, the IRT (Independent Review Team) believes they found root cause ( which incorrectly polled time from the Atlas V booster nearly 11 hours prior to launch.) and provided a number of recommendations and corrective actions.
- The IRT also investigated a valve mapping software issue, which was diagnosed and fixed in flight. That error in the software would have resulted in an incorrect thruster separation and disposal burn. What would have resulted from that is unclear(catastrophic).
- The IRT is also making significant progress on understanding the command dropouts encountered during the mission and is further investigating methods to make the Starliner communications system(Space to Ground forward link) more robust on future missions.
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