Boeing said Monday it has re-qualified software for the company’s Starliner crew capsule after programming errors cut short the spacecraft’s first orbital test flight in 2019, and technicians at the Kennedy Space Center have connected the crew and service modules for the next unpiloted Starliner test flight to the International Space Station in March.
NASA and Boeing officials are officially targeting March 29 for the second Starliner Orbital Flight Test, a repeat of the first test flight in 2019, when software problems prevented the capsule from docking with the space station. Boeing and NASA managers agreed last year to re-fly the OFT mission to demonstrate an entire Starliner flight sequence before clearing the craft to fly astronauts.
The Starliner safely landed in New Mexico, but engineers kicked off a review of all the spacecraft’s software code to prevent a repeat of the problems on the first OFT mission.
Multiple NASA and industry officials have said the launch of the OFT-2 mission could be moved forward to around March 25. Boeing’s Starliner missions lift off on United Launch Alliance Atlas 5 rockets from Cape Canaveral Space Force Station, and the capsule lands under parachutes at one of several sites in the Western United States.
The OFT-2 mission will lay the groundwork for the next Starliner test flight to carry three NASA astronauts to the space station later this year, followed by the start of regular crew rotation flights.
Boeing said Monday that engineers have completed a “full review” of the Starliner’s flight software. Teams also evaluated the process for qualifying modifications and upgrades to the software in the future, the company said.
“The work this team put into exhaustively wringing out our software is a defining moment for the program,” said John Vollmer, Starliner vice president and program manager, in a statement. “We’re smarter as a team having been through this process, and most importantly, we’re smarter as a human spaceflight community.”
Meanwhile, a Boeing spokesperson said technicians inside the Commercial Crew and Cargo Processing Facility at NASA’s Kennedy Space Center mated the crew and service modules last week for the OFT-2 mission, a major milestone in readying the spacecraft for launch.
Assuming the OFT-2 mission sticks with a launch date around March 25, Boeing teams will load the Starliner with hypergolic maneuvering propellant next month before transporting the capsule to the Atlas 5 launch pad.
One change to the hardware for the OFT-2 mission is the installation of a new docking system cover on the nose of the Starliner crew module. The door is designed to better protect the sensitive docking port components during the heat of re-entry, and will help ensure the Starliner crew modules can be reused at least 10 times, per the spacecraft’s design specifications, officials said.
The door will open once the Starliner reaches orbit, revealing the craft’s docking interface to connect with the space station. After undocking, the door will close for re-entry. The cover is similar in purpose to the nose cone door on SpaceX’s Crew Dragon spacecraft.
Boeing plans to rotate between two reusable crew modules for all planned Starliner missions. Each flight will use a new service module, which provides propulsion and power generation capacity for the spacecraft. The crew module from the OFT-1 mission is being refurbished for Boeing’s Crew Test Flight, the first Starliner mission with astronauts.
NASA awarded contracts to Boeing and SpaceX in 2014 to develop the Starliner and Crew Dragon spaceships to ferry astronauts to and from the space station. Both programs have encountered technical delays, but SpaceX successfully launched its first two crew missions — a test flight and its first operational crew rotation mission — last year, restoring orbital human spaceflight capability to the United States for the first time since the end of the space shuttle program in 2011.
The start of operational flights with Boeing’s Starliner will give the United States two independent spacecraft designs capable of carrying crews into low Earth orbit for the first time in the history of the space program.
Boeing said the software re-qualification milestone sets the stage for an end-to-end simulation of the OFT-2 test flight in the the company’s Avionics and Software Integration Lab in Houston. The end-to-end simulation will use “flight hardware and the final versions of Starliner’s flight software to accurately model the spacecraft’s expected behavior,” Boeing said.
The simulation will last several days, testing software functionality from pre-launch to docking, and undocking to landing, according to Boeing.
The end-to-end rehearsal was not performed to verify software code before the OFT-1 mission. An independent NASA-Boeing review team issued 80 recommendations aimed at providing more thorough software testing, process improvements, and some hardware changes.
The investigators also recommended NASA officials improve their oversight of Boeing’s Starliner team.
The software re-qualification effort involved ensuring the Starliner simulators and emulators were properly configured to mimic how the real spacecraft works in flight. Engineers then reviewed and updated the spacecraft’s software code, and completed tests inside the software integration lab.
Boeing said the testing included “hundreds of cases ranging from single command verifications to comprehensive end-to-end mission scenarios with the core software.”
United Launch Alliance, Starliner’s launch provider, and NASA are involved in the software testing to ensure proper integration during the spacecraft’s ascent into orbit, and docking and undocking at the space station.
“As we continue carrying out these critical milestones and reviews, we remain true to our values of safety, quality and integrity,” Vollmer said. “Completing OFT-2 brings us one step closer to our end goal of transporting astronauts to and from the International Space Station this year.”
The software errors discovered during the OFT-1 mission in December included a Starliner 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 International 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.
The OFT-2 mission is expected to last around one-to-two weeks.
Phil McAlister, NASA’s director of commercial spaceflight, said last week that SpaceX’s next Crew Dragon mission — with four astronauts — is scheduled to launch in March or April, around the same time as the Starliner OFT-2 test flight.
The space station has two docking ports to receive commercial crew capsules, but the next Crew Dragon flight — known as Crew-2 — will arrive at the complex before departure of the current Crew Dragon mission.
That means the OFT-2 test flight cannot launch during the handover between the Crew-1 and Crew-2 missions.
“We will de-conflict those missions as we get a little bit closer, depending on the readiness of the spacecraft and the needs of the ISS,” McAlister said Jan. 13 in a meeting of the NASA Advisory Council’s Human Exploration and Operations Committee.
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