Boeing’s Starliner capsule returns to hangar for valve troubleshooting

United Launch Alliance’s Atlas 5 rocket and Boeing’s Starliner capsule depart pad 41 at Cape Canaveral Space Force Station on Thursday morning. Credit: Boeing

Ground teams at Cape Canaveral wheeled Boeing’s Starliner crew capsule and a United Launch Alliance Atlas 5 rocket back inside their assembly hangar Thursday for further troubleshooting of misbehaving valves inside the Starliner propulsion system.

Without a quick fix, technicians will have to remove the spacecraft from the Atlas 5 rocket for more extensive work, potentially delaying the unpiloted Starliner Orbital Flight Test-2 mission to the International Space Station by months.

ULA has already taken measures to protect for the possibility that the Starliner’s Atlas 5 rocket might have to be disassembled to allow the company to move on to other missions on its launch schedule. Before rolling the Atlas 5 back into the hangar, ULA drained the first stage’s fuel tank of kerosene.

Standing on a mobile launch platform, the 172-foot-tall (52.4-meter) rocket moved off its launch mount on pad 41 at Cape Canaveral Space Force Station and back into ULA’s Vertical Integration Facility late Thursday morning.

With the Atlas 5 and Starliner back in the VIF, workers planned to install access platforms and begin another round of troubleshooting in a bid to find the reason propulsion valves inside the spacecraft appear to be in unexpected positions.

The valve issue caused Boeing to order a scrub during a launch attempt Tuesday. Additional checks ruled out a number of potential causes, including software, Boeing said.

Engineers noticed the valves were misbehaving after a lightning storm that passed over the launch pad Monday. Boeing said the severe weather appears to be an unlikely cause for the problem, but teams inside the VIF will inspect the spacecraft’s “doghouse” propulsion pods for water or electric damage.

But not all of the doghouses are accessible in the VIF, and commands to cycle the valves while the spacecraft was on the launch pad yielded no change in the position indications.

The propulsion system valves in question are inside the Starliner’s service module, which has an array of rocket thrusters designed to propel the spacecraft away from its launcher during an in-flight emergency. Other thrusters on the service module are used for in-orbit maneuvers and spacecraft pointing control.

Boeing said in a statement one of the first steps after the spacecraft arrived back in the VIF was to power up the Starliner capsule, which takes several hours. Then engineers will send commands to cycle the valves. If that doesn’t work, teams could try to command the valves using different methods.

“We’re letting the data drive our decision-making and we will not fly until our integrated teams are comfortable and confident,” said John Vollmer, vice president and program manager of Boeing’s commercial crew program.

The next launch opportunities for the Starliner mission are on Saturday and Sunday, but completing the Starliner inspections and testing — and resolving any potential problem on the service module — in time for a weekend launch is unlikely, sources said.

If the valve problem persists, Boeing is expected to detach the Starliner capsule from the top of the Atlas 5 rocket and return it to the company’s spacecraft factory at the nearby Kennedy Space Center.

That would put the launch schedule for the OFT-2 mission up against several other important NASA missions in the next couple of months.

A SpaceX Cargo Dragon capsule is set for launch Aug. 28, and it will use the same docking port needed by the Starliner spacecraft. The Dragon spaceship will occupy the space station docking port until late September.

NASA’s Lucy asteroid science probe is scheduled for liftoff during a 23-day planetary launch period opening Oct. 16. Like the Starliner mission, Lucy will use a United Launch Alliance Atlas 5 rocket to depart Earth and head into the solar system for encounters with eight asteroids, a record number for a single mission.

Lucy can only launch when Earth is in the right position in its orbit around the sun, relative to its asteroid targets. The robotic mission has a backup launch period in October 2022, but the spacecraft has already been shipped from its Lockheed Martin factory in Colorado to Cape Canaveral to begin final launch preparations.

Another Atlas 5 launch was scheduled for liftoff in early September carrying experimental satellites for the U.S. military’s Space Test Program. That mission, designated STP-3, may have to be postponed until after the Lucy launch following the delays in getting the Starliner’s OFT-2 mission off the ground.

If it looks likely to take more than a couple of weeks to resolve the Starliner valve issue, ULA is expected to disassemble the Atlas 5 launcher and begin stacking the next Atlas 5 rocket for launch from Cape Canaveral. With little time to fit in the STP-3 mission, that will likely be the Atlas 5 rocket for the Lucy launch.

ULA also has an Atlas 5 rocket set for launch Sept. 16 from Vandenberg Space Force Base in California with the Landsat 9 Earth-imaging satellite NASA and the U.S. Geological Survey. The company needs about a week between Atlas 5 launches from Vandenberg and Cape Canaveral. If Landsat 9’s launch remains set for Sept. 16, that would preclude the launch of any Atlas 5 mission from Florida for a couple of weeks in mid-September.

Once the OFT-2 mission is cleared for takeoff, the Starliner spacecraft will dock with the space station, where the lab’s crew will open hatches leading to the crew capsule. The station crew members will unload several hundred pounds of cargo and inspect the capsule’s crew cabin.

A test dummy named “Rosie the Rocketeer” will occupy one of the capsule’s seats on OFT-2.

The Starliner crew capsule is launching on a do-over of the problem-plagued OFT-1 demo mission in 2019 that failed to reach the space station. Boeing and NASA blamed the botched mission on software programming errors, and managers say extra testing has resolved the software concerns ahead of this mission.

Boeing developed the CST-100 Starliner spacecraft under contract to NASA, which has similar agreements with SpaceX for that company’s Crew Dragon program. SpaceX’s capsule began flying astronauts to the space station last year, and Boeing is now more than a year behind.

Both companies have contracts with NASA for at least six commercial crew missions to the space stations. SpaceX has already launched two of its operational crew rotation flights.

Before Boeing can move on to its first crewed test flight, NASA managers want to ensure the contractor has resolved the software woes that cut short the 2019 test flight. The Starliner test flight will also prove out the spacecraft’s rendezvous and docking systems, which were unused on the 2019 mission.

Source

Subscribe
Notify of
0 Comments
Inline Feedbacks
View all comments
0
Would love your thoughts, please comment.x
()
x