Starliner capsule fueled for unpiloted test flight to International Space Station

Boeing’s Starliner spacecraft is prepared for launch on the Orbital Flight Test-2, or OFT-2, mission. Credit: Boeing

Boeing finished loading hydrazine and nitrogen tetroxide maneuvering propellants over the weekend into the company’s second space-rated Starliner capsule at the Kennedy Space Center, days after stacking of its Atlas 5 launcher began a few miles away at Cape Canaveral Space Force Station.

The capsule is scheduled to launch July 30 at 2:53 p.m. EDT (1853 GMT) on a test flight to the space station. If all goes according to plan, it will clear the way for Boeing to carry astronauts to the station, possibly before the end of this year.

That will be welcome news to NASA, which has funded the Starliner spacecraft’s development through its a commercial crew program in a cost-sharing arrangement with Boeing. NASA’s commercial crew contracts with Boeing since 2010 are valued at more than $5 billion.

NASA has a similar set of contracts with SpaceX valued at more than $3 billion for development of the Crew Dragon spacecraft. The contracts for both companies included a minimum of six operational crew rotation flights to the International Space Station.

Boeing appeared on track to launch its first Starliner crew mission in 2020, but the Starliner’s first unpiloted test flight in December 2019 ended prematurely without docking with the space station. Boeing and NASA officials blamed the botched test flight on software issues, including a mission elapsed timer clock that was incorrectly set before launch.

The problem caused the spacecraft’s computer to think it was in a different flight phase after deployment from the Atlas 5 rocket in orbit, causing the to capsule fire thrusters and burn too much propellant. The higher-than-expected fuel usage prevented the Starliner spacecraft from docking with the space station.

Ground teams uncovered another software coding error that could have caused the spacecraft’s service module to collide with the crew module after the two elements separated just before re-entry. During certain parts of the shortened two-day mission, there were also difficulties establishing a stable communications link between the Starliner spacecraft and NASA’s network of tracking and data relay satellites.

Despite the problems, the capsule returned to Earth for a parachute-assisted, airbag-cushioned landing at White Sands Space Harbor, New Mexico.

Boeing is now refurbishing that capsule for the Starliner Crew Flight Test. But first, Boeing and NASA managers agreed to launch a second Orbital Flight Test, a mission called OFT-2, to wring out the spacecraft’s software and complete the demonstration tasks left unaccomplished by the OFT-1 mission in 2019.

A second Starliner crew module will fly on the OFT-2 mission. Once it is back on Earth, Boeing will refurbish the capsule for future crew missions. Every Starliner mission will feature a new service module, which burns up during re-entry.

But the OFT-2 mission has to well before Boeing and NASA can finalize a schedule for the Crew Flight Test.

The first stage of the Atlas 5 rocket for the Starliner spacecraft’s OFT-2 mission was hoisted on its launch platform June 17 at Cape Canaveral Space Force Station. Credit: United Launch Alliance

Boeing said last week that engineers have closed out all recommendations from a joint NASA-Boeing independent review team set up to investigate the problems on the OFT-1 mission. The review team issued 80 recommendations, including more thorough integrated software testing and mission simulations, process improvements, crew module communication system improvements, and organizational changes.

“Boeing has implemented all recommendations, even those that were not mandatory, ahead of Starliner’s upcoming flight,” the company said in a statement.

Earlier this year, Boeing completed an end-to-end mission simulation in the company’s Avionics and Software Integration Lab in Houston. The test combined flight hardware and the final version of the spacecraft’s flight software.

The end-to-end rehearsal was not performed to verify software code before the OFT-1 mission in 2019.

“I am extremely proud of the NASA and Boeing Starliner teams as they methodically work toward the OFT-2 mission next month with final checks of the crew module and service module hardware and software as we prepare for this important uncrewed test mission,” said Steve Stich, manager of NASA’s commercial crew program.

“Closing all of the independent review team findings for the software and communications systems is a huge milestone for the commercial crew program and included many long hours of testing and reviews by our dedicated Boeing and NASA teams during this Covid-19 pandemic,” Stich said in a statement.

In parallel with the software testing, Boeing technicians at the Commercial Crew and Cargo Processing Facility at the Kennedy Space Center have finished the bulk of the preparations on the spacecraft for the OFT-2 mission.

In January, Boeing mated the crew module and service module inside the processing facility, a former space shuttle hangar.

A Boeing spokesperson said Monday that the crew and service modules have been fully loaded with their mix of hypergolic propellants, which will feed the spacecraft’s thrusters for maneuvers to rendezvous with the space station and the de-orbit burn at the end of the mission.

United Launch Alliance, a 50-50 joint venture between Boeing and Lockheed Martin, is the launch provider for Starliner missions. On June 17, ULA raised the first stage of the Atlas 5 rocket for the OFT-2 mission on its launch platform inside the Vertical Integration Facility near pad 41 at Cape Canaveral Space Force Station.

ULA planned to install two strap-on solid rocket boosters and a dual-engine Centaur upper stage on the Atlas 5 rocket, setting the stage for delivery of the Starliner spacecraft to the VIF in mid-July. There will be no pre-launch fueling rehearsal on the Atlas 5 rocket before the OFT-2 mission.

“In the weeks ahead, mission control teams in Florida and Texas will continue conducting simulated mission dress rehearsals for the uncrewed OFT-2 and follow-on crewed missions. Starliner’s landing and recovery teams also will perform an on-site checkout of one of the vehicle’s landing zones,” Boeing said in a statement.

Technicians also loaded cargo into the Starliner’s pressurized crew module, which will fly with an instrumented test dummy in one of its seats. The OFT-2 mission will deliver around 440 pounds (200 kilograms) of cargo and crew supplies to the space station.

Assuming the mission launches July 30, the Starliner spacecraft is scheduled to dock July 31 with the forward port of the space station’s Harmony module.

In late July, before the Starliner’s arrival, four of the space station’s seven crew members will strap into their SpaceX Crew Dragon spaceship for a relocation from thee forward docking port to an upper port on the Harmony module. That will clear the way for the Starliner’s docking.

Boeing said the OFT-2 mission is expected to last about five to 10 days before undocking from the station and returning to Earth. The capsule will target one of five landing zones in the Western United States, including two locations at White Sands Missile Range in New Mexico, and sites in Utah, Arizona, and California.

The Starliner’s undocking, re-entry, and landing is tentatively scheduled for Aug. 5. On that date, the primary landing site will be at White Sands.

NASA astronauts Barry “Butch” Wilmore and Mike Fincke welcome to Cape Canaveral the Atlas 5 rocket that will carry them into orbit on the Starliner Crew Flight Test. Credit: Alex Polimeni / Spaceflight Now

If the OFT-2 mission achieves all its objectives, Boeing and NASA officials will “look for opportunities toward the end of the year” to launch the Starliner Crew Flight Test. That mission, which also launch on an Atlas 5 rocket, will carry NASA astronauts Barry “Butch” Wilmore, Mike Fincke, and Nicole Mann to the International Space Station.

The Atlas 5 first stage and Centaur upper stage for the Crew Flight Test arrived Sunday at Port Canaveral after riding ULA’s transport ship from a factory in Decatur, Alabama.

Ground crews unloaded the rocket stages from the vessel Monday to begin launch processing at Cape Canaveral Space Force Station.

The OFT-2 mission will use the Atlas 5 rocket originally assigned to the Crew Flight Test.

If the piloted demonstration flight goes well, NASA will clear Boeing for the first of its six operational crew rotation missions to the space station in 2022.

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Follow Stephen Clark on Twitter: @StephenClark1.