The launch of Friday and the landing on Sunday of the first Boeing Starliner spacecraft were picture perfect. However, the orbital flight that took place in between left much to be desired. Ars Technica explains the software glitch that preventing the Starliner from rendezvousing and docking with the International Space Station.
“After being released by the rocket, Starliner was supposed to use its Orbital Maneuvering and Attitude Control engines to provide the thrust needed to reach a stable orbit 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. The on-board computer then expended a significant amount of propellant to maintain a precise attitude, thinking it had reached orbit.”
By the time the flight controllers on the ground found out that the glitch had occurred, it was too late to make corrections.
“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.”
NASA and Boeing jointly made the decision not to try to go for the ISS, but to make as many tests of the spacecraft as possible before bringing it down at the White Sands Missile Range 48 hours after the spacecraft was launched. In the meantime, officials from both NASA and Boeing chose to be upbeat about the fact that the Starliner performed nominally during the two days that it was in Earth orbit. The space agency and the big aerospace company garnered an enormous amount of data about the spacecraft during its truncated flight that will be of great benefit during subsequent flights. The data included some from sensors attached to a mannikin strapped in one of the crew seats dubbed “Rosie the Rocketeer.” The data from “Rosie” will inform engineers how the flight would have affected a human astronaut.
The Starliner executed a deorbit burn while it was still over the Pacific Ocean. The spacecraft detached the service module and then hit the atmosphere as so many space capsules have before, enduring an immense amount of heat as the air hit its heat shield. The Starliner passed through this phase intact. It deployed its drogue parachutes to stabilize it in the landing position. Then the spacecraft deployed its main chutes to slow it down enough so that it soft-landed on an airbag on the New Mexico desert.
While the flight of the Starliner achieved a great many test objectives, the fact remains that the spacecraft did not rendezvous, approach, and dock with the ISS. The primary purpose of the Starliner is to take astronauts to and from the orbiting laboratory.
However, both NASA and Boeing officials were quick to point out that had the Starliner contained a crew on board, it would have been able to detect the timer glitch and take manual control of the spacecraft. Pending the analysis of the data that has been garnered, they have to determine whether another uncrewed test flight will be needed or whether Boeing can go directly to a crewed test flight. If the former, the timeline for getting the Starliner operational will have at least a three-month delay.
The next event for the commercial crew program will be a flight abort test for the other spacecraft in the program, the SpaceX Dragon. Should that test prove to be successful, the Dragon will be cleared for a crewed flight test sometime in the spring. Whatever happens, NASA hopes that both the Dragon and the Starliner will become operational in 2020, ending America’s dependence on Russia for taking astronauts to and from space.