Boeing focuses on cause of Starliner launch delay – Spaceflight Now
STORY WRITTEN FOR CBS NEWS AND USED WITH PERMISSION
Engineers are focusing on the “root cause” of a disappointing launch scrub in August that brought Boeing’s Starliner astronaut ferry to a standstill: moisture-induced corrosion in the main valves of the propulsion system, the engineers said on Tuesday. company officials.
Corrective actions are being developed while troubleshooting continues, but another attempt to launch the Starliner on an unmanned test flight to the International Space Station is not expected until next year, probably delaying the first piloted mission even later.
In the meantime, NASA will continue to rely on SpaceX and its Crew Dragon operational capsules to send astronauts to and from the station with the next flight scheduled for Halloween. The next Crew Dragon flight after that is scheduled for mid-April.
John Vollmer, director of Boeing’s commercial crew program, said the company’s primary goal with the Starliner is to fly safely, “and I insist on safety,” as soon as possible.
“Everything that we have done so far, and the path that we are developing in the future, will enable us to achieve this goal of returning to flight safely,” he said. “We’ve looked at the options for moving forward and… that puts us somewhere in the first half of 2022.”
As for the cost, Vollmer said “there is no additional cost that will be charged to the government for this. This is something that the Boeing Company will make sure we have covered while we prepare this vehicle. We are 100% committed to fulfilling our contract with the government, and we intend to do so. “
In 2014, SpaceX won a $ 2.6 billion contract with NASA to develop its Crew Dragon spacecraft while Boeing received $ 4.2 billion to develop the Starliner. The spacecraft was intended to end NASA’s post-shuttle dependence on Russia’s Soyuz and bring human space launch back to American soil.
Boeing had initially scheduled two Starliner test flights, one unmanned and the other with a crew. Both were intended for rendezvous and docking with the International Space Station.
The first “Orbital Flight Test 1” unmanned spacecraft, or OFT-1, was launched on December 20, 2019, but the flight was marred by a serious software error and communication issues that blocked the rendezvous. planned from the space station. Another error could have caused a catastrophic failure if it had not been detected before re-entry.
After a thorough investigation, the software and communication issues were fixed, a host of other upgrades and enhancements were implemented, and Boeing scheduled a second unmanned test flight, at the expense of the company, for August 3.
But during a routine pre-launch test of the propulsion system in the Starliner’s service module, telemetry indicated that 13 of the 19 valves did not respond as expected.
OFT-2’s launch was delayed for troubleshooting, and while engineers ultimately made nine of the 13 open using higher voltages and heaters to release stuck components, four refused to budge. Boeing then chose to return the capsule to its processing plant for further analysis.
Inspections revealed signs of corrosion in the valves, seeming to confirm what engineers suspected early on: The moisture, likely the result of Florida’s summer humidity, somehow seeped into the valves where it reacted with the nitrogen tetroxide propellant which had seeped through the internal Teflon seals. The result was the formation of nitric acid and corrosion.
The infiltration of propellant through the Teflon seals is not unusual and is controlled by limiting the length of time the propellant is on board. The Starliner was well within the normal 60-day limit.
But given the high humidity, rain, and thunderstorms are no surprise in Florida, “everyone is asking this question, why didn’t we know that before we went to the pad? Vollmer said.
“Just to be clear,… we have operated these valves many times in the plant when we installed them, when we checked them, during environmental qualification tests. … We had no indication that there would be a problem with these valves.
And there was no sign of a problem during a launch pad abandonment test, thruster “hot fire” tests, and the OFT-1 mission.
“We really had no indication or reason to believe that these valves would not work,” Vollmer said.
The toxic thrusters have now been drained from the service module tanks and two valves have been removed to be shipped to NASA’s Marshall Space Flight Center in Alabama for computed tomography, teardown and more detailed inspections.
Further testing is planned at a facility in New Mexico where engineers will attempt to duplicate the failure mode using the same environmental conditions present during the actual countdown.
In the meantime, engineers are making plans to add desiccators to the valves, possible heaters, and a more powerful dry air pre-launch purge to prevent condensation inside the service module.