On July 28, the International Space Station (ISS) suffered a mishap after a new Russian module (named Nauka) fired its engines just hours after it arrived. As a result, the entire station was temporarily pushed out of position, which forcibly delayed the Orbital Flight Test-2 (OFT-2) mission. This would have been the second attempt by Boeing’s CT-100 Starliner to meet with the ISS as part of NASA’s Commercial Crew Program (CCP).
The ISS managed to correct its orbit shortly afterwards, while the OFT-2 launch was postponed to the next available opportunity (Wednesday, August 4). Unfortunately, the mission was delayed again due to a problem with one of the valves on the spacecraft’s propulsion system. This prompted the ground crews to relocate the Starliner and Atlas V launcher back to the Vertical Integration Facility (VIF) so that they can more precisely identify the source of the problem.
The OFT-2 mission will be the Boeing CST-100 Starliner’s second attempt to dock with the ISS after failing its previous attempt (December 2019). The Starliner, known as the OFT-1 mission, successfully reached space with no problems, but a malfunction in the clock prevented the thrusters from firing at the correct time. As soon as they fired, they burned more fuel than expected, making the planned rendezvous with the ISS impossible.
A ULA Atlas V rocket with Boeing’s CST-100 Starliner spacecraft on the launch pad of Space Launch Complex 41 at Space Force Station Cape Canaveral, Florida. Photo credit: NASA / Aubrey Gemignani
This planned mission would have been the last unmanned flight test designed to validate the Starliner for carrying out replenishment and crew missions to the ISS. SpaceX completed an unmanned flight test (Demo-1) with its Crew Dragon spaceship, which successfully hit the ISS on March 2, 2019. Demo-2 followed, during which astronauts Robert Behnken and Douglas Hurley flew to the ISS.
The OFT-2 flight would have brought Boeing one step closer to securing contracts with NASA for the flight of cargo and crews to the ISS. Before that can happen, NASA and Boeing need to analyze the Starliner and figure out why not all of its valves were in the correct configuration for launch. NASA and Boeing have already taken several steps to fix the incorrect valve readings.
This included switching the valves of the service module propulsion system on and off while the Starliner was still in its launch configuration on the Atlas V rocket of the United Launch Alliance (ULA) in Space Launch Complex-41 at Space Force Station Cape Canaveral in Florida found. At this point, the teams also ruled out a number of other potential causes (such as a software bug), but it was clear that an additional assessment was needed.
After the engineering teams presented their initial results to NASA and Boeing managers on August 4th, they decided that the Atlas V and Starliner would be moved to the VIF for further inspection and testing. With the VIF assembling support structures that secure the spacecraft’s service module, engineers now have direct access to the Starliner and can perform a more thorough analysis.
A ULA Atlas V rocket with Boeing’s CST-100 Starliner spacecraft on board can be seen near the VIF at Cape Canaveral Space Force Station in Florida. Photo credit: NASA / Joel Kowsky
This consists in Boeing powering up the Starliner so the vehicle can receive commands that provide real-time data to the teams. This data is then used to inform you of any corrective action that may be required to ensure that the CST-100 arrives at the next opportunity to take off. Steve Stich, manager of the Commercial Crew Program, said in a recent update on the NASA blog:
“The Boeing and NASA teams are working methodically to understand what caused the valve indicators on the Starliner service module propulsion system. Troubleshooting the Vertical Integration Facility will help focus on potential causes and next steps before we fly the OFT-2 mission. “
“This mission is extremely important for the Commercial Crew Program on the way to the Boeing Crewed Flight Test. We will fly the mission when we are ready. I am very proud of the NASA and Boeing teams for their professionalism, perseverance and methodical approach to solving complex problems. “
In the meantime, this assessment has given the crew aboard the ISS (Expedition 65) time to further check the newly arrived Nauka module from Roskosmos and ensure that the station is ready for Starliner’s arrival. The continued analysis of the unplanned engine firings has shown that the space station experienced an overall change in attitude of around 540 °, but that the maximum speed and acceleration did not come close to the safety limits for the ISS systems.
The Aurora australis appears to crown the earth’s horizon as the International Space Station orbited 272 miles over the southern Indian Ocean between Asia and Antarctica. Photo credit: NASA
The analysis also confirmed that once situation control was restored and the station is currently in good condition and all of its systems are functioning normally, normal operations would resume. Since then, the Expedition 65 crew has resumed normal operations, including unpacking the cargo that was delivered to the new Nauka Multipurpose Laboratory Module (MLM).
The crew also resumed scientific operations, such as the InSpace-4 study of space fabrication in the microgravity science glove box. This experiment aims to explore ways to harness nanoparticles and develop advanced materials in microgravity to improve space and earth systems. The crew will also watch the Cygnus spacecraft as it approaches the space station a day and a half after its launch on Tuesday, August 10th.
The crew is also preparing for another spacewalk to prepare the ISS Port-4 truss structure prior to installing the station’s next solar panels. And when all of the Starliner’s systems are checked out, the OFT-2 mission will be postponed to the first available launch opportunity and (subject to further problems) another manned mission will be launched from US ground.
On earth and in orbit, work continues to secure the future of space exploration, commercial space, and space exploration!
Further reading: Business Insider, NASA