Before Boeing’s Starliner crew cabin is cleared to leave the International Space Station and head for Earth, NASA managers want to make sure the spacecraft’s troubled control thrusters can help guide the ship’s two-man crew home.
The two astronauts who launched June 5 on the first test flight of the Starliner spacecraft agree with managers, though they said Wednesday that they are comfortable flying the capsule back to Earth should there be an emergency that might require the evacuation of the space station. station.
NASA astronauts Butch Wilmore and Suni Williams were supposed to return to Earth weeks ago, but managers are keeping them at the station as engineers continue to probe problems with the jets and helium leaks that have plagued the mission since its launch.
“It’s a tough thing we’re in,” Wilmore, the Starliner commander, told reporters Wednesday at a news conference from the space station. “Human spaceflight is not easy in any mode and with every spacecraft that’s ever been designed, and that’s the nature of what we do.”
Five of the 28 thrusters of the reaction control system on the Starliner’s service module failed as the spacecraft approached the space station last month. The Starliner’s flight software disabled the five control thrusters as they began to overheat and lose thrust. The four thrusters were later restored, although some could not reach their full power as the Starliner came to dock.
Wilmore, who took manual control of the Starliner’s approach portion to the space station, said he felt the spacecraft’s performance diminish as the thrusters temporarily failed. “You could say it was degraded, but it was still impressive,” he said. The Starliner eventually docked with the station in autopilot mode.
In mid-June, the Starliner astronauts re-ignited the thrusters and their thrust levels returned to normal.
“We want to know that the jets can work; if their thrust percentage is whatever, we can put it in a package that gives us a deorbit burn,” said Williams, a NASA astronaut serving as the Starliner pilot. “That’s the main purpose we need. [for] service module: to give us a good deorbit so we can return.”
These small thrusters are not necessary for the de-orbit burn itself, which will use another set of engines to slow the Starliner down enough to drop out of orbit and head for a landing. But the Starliner needs enough thrusters to maneuver itself into the correct orientation for launch from orbit.
The test flight marks the first time astronauts have flown into space on Boeing’s Starliner spacecraft after years of delays and setbacks. The Starliner is NASA’s second human-rated commercial crew and is set to join SpaceX’s Crew Dragon in a rotation of missions carrying astronauts to and from the space station for the rest of the decade.
But first, Boeing and NASA must safely complete the Starliner’s test flight and resolve the problems with the thrusters and helium leaks plaguing the spacecraft before moving forward with crew-rotating operational missions. A Crew Dragon spacecraft is currently attached to the station, but Steve Stich, NASA’s commercial crew program manager, told reporters Wednesday that right now Wilmore and Williams still plan to return home on the Starliner.
“The beauty of the commercial crew program is that we have two vehicles, two different systems that we could use to return the crew,” Stich said. “So we have a little more time to go over the data and then decide if we need to do anything differently. But the main option today is to put Butch and Suni back on the Starliner. We’re not doing that right now.” see any reason why it should not be so.”
Mark Nappi, Boeing’s Starliner program manager, said officials have identified more than 30 actions to investigate five “minor” helium leaks and nozzle problems on the Starliner’s service module. “All these items are to be completed by the end of next week,” Nappi said.
“It’s a test flight and the first with a crew, and we’re just taking a little extra to make sure we understand everything before we commit to deorbit,” Stich said.