What was originally found soon after the first scrubbed launch attempt back in May and determined to be a manageable helium leak, has since turned into a bigger problem in space. Specifically, after the first launch scrub, officials discovered a leak in one of Starliner’s RCS thrusters. While not ideal, they decided that it was manageable, and that it could be left as is even during the launch.
Unfortunately, not long after this morning’s successful launch with two crew members aboard, the problem has gotten worse, with even more helium leaks being found. This comes as the crew prepares to try and dock to the International Space Station in the morning. Here I will go more in-depth into the new leaks, their significance, what this means for the rest of the mission, and more.
More Helium Leaks
Around 6 or so hours after the launch reports started coming out that there was a problem developing related to helium leaks on Starliner. In this case, Capcon communicated with the propulsion officer and let the crew know that they had picked up more helium leaks. The specific areas within the spacecraft they were focusing on included the top helium manifold 1 and port helium manifold 1. Around the time they were first announced on the official NASA live stream, they were quoted saying, “The crew worked through the steps to close them and those jets are unavailable. There were no burns planned in the immediate 8 hours or so.” They went on to say, “So when dealing with these helium leaks, CapCon was communicating with Butch and Sunny on what they can expect.” Around this time was right when the crew was getting ready to go to bed before waking up the next morning and working to rendezvous and actually dock to the station.
Despite the new leaks, they did some initial work while the crew was still awake but then continued with the original plan and green-lighted both astronauts to go to sleep. The plan from there was for crews to work the issue while the astronauts were resting.
Not long after this, some more context was provided during NASA’s livestream by a Boeing engineer. Here he was quoted saying, “As your know prior to launch our team was monitoring a small leak on Starliner’s propulsion system. Teams took a closer look at that system before crews went to sleep. They closed all the helium manifold valves to collect data on that system and observed two more small leaks, one of those leaks being in port 2, one being in port 1, and one being in top 1” he said. In other words, they knew of one original leak which was in port 2, and ended up finding two additional leaks not long after launch.
Focusing more on the location and how they were found, they first tested all 8 of Starliner’s helium manifolds, and found that the leak was isolated to one flange in one of the spacecraft’s 28 RCS thrusters or Reaction Control System Thrusters which are used to make small adjustments while the vehicle is on orbit. More specifically it was on a seal (about the size of a button on a shirt).
In another quote, the Boeing Engineer said, “I want to note that Helium is not combustible or toxic. But overnight we’re going to keep the top 1 and port 1 closed and they will open port 2. That will give the team the ability to manage the spacecraft. We do have confirmation from our engineering support teammates at Boeing that the helium system remains safe for flight. This is not unexpected and we plan for cases like this. The team will be working to make sure that we are in a good configuration to complete our mission which is docking with the ISS” they said. Besides these comments, they stressed that the crew is in no danger.
This does however bring up questions related to the rest of the mission and what to expect. While the problem seems to be manageable now and there are a limited number of burns needed until the morning, what about docking and eventually reentry? In the morning we can expect even more information on the leaks and what NASA and Boeing have determined is the best course of action. Ideally, the leaks are small enough or can be controlled to the point where the mission is unaffected. The fact that the crew is sleeping is a good sign that NASA and Boeing aren’t too concerned with the issue that it would warrant the astronauts staying up and working on the issue as well. Something we should get more information on in the coming hours.
Data Before The Launch
This all comes back to the original Helium leak and the decision to leave it as is. When the leak within Starliner was discovered back in May, teams began working to resolve the issue within the service module that was traced to a flange on a single reaction control system thruster. Around a week after the initial scrub and discovery of the additional helium leak, Boeing and NASA decided to conduct some tests. Specifically, as part of the testing, Boeing planned to bring the propulsion system up to flight pressurization just as it does prior to launch, and then in theory, allow the helium system to vent naturally to validate existing data and strengthen flight rationale.
They eventually conducted this test and said in a company statement, “Pressure testing performed on May 15 on the spacecraft’s helium system showed the leak in the flange is stable and would not pose a risk at that level during the flight. The testing also indicated the rest of the thruster system is sealed effectively across the entire service module. Boeing teams are working to develop operational procedures to ensure the system retains sufficient performance capability and appropriate redundancy during the flight. As that work proceeds, NASA’s Commercial Crew Program and the International Space Station Program will take the next few days to review the data and procedures to make a final determination before proceeding to flight countdown.”
In addition to this, before the launch, Steve Stich, NASA commercial crew program manager, said engineers believed that a seal, a rubber ring about the thickness of 10 sheets of paper, in the flange had a defect that grew worse during tests. He said other possibilities included an error installing the seal or foreign object debris that rubbed against the seal. One original quote that directly addressed the decision to fly with the leak was “If we were to remove the seal completely, the leak rate would not exceed our capability to manage that leak.” said Mark Nappi, Boeing vice president and commercial crew program manager. That made us comfortable that, if this leak were to get worse, it would be acceptable to fly” he said.
While they didn’t seem too concerned, when the study of the helium leak was ongoing, Stich said engineers performed a review of the rest of the propulsion system just to make sure they didn’t have any other things that they should be concerned about. However, that review did actually turn up something he called a “design vulnerability” with Starliner’s propulsion system where, in a rare circumstance, the spacecraft would not be able to perform a deorbit burn if two adjacent “doghouses” that contain RCS and larger orbital maneuvering and attitude control (OMAC) thrusters failed. That failure, he said, would knock out enough OMAC and RCS thrusters to prevent existing backup plans for carrying out a deorbit burn from being implemented. To solve this issue in a timely manner, engineers developed a different deorbit reentry mode that would alter the burns from the RCS. They highlighted that this outcome would be highly unlikely but something they want to prepare for just in case. At this point, the hope is that the leaks are kept under control and don’t cause any significant issues or mission alterations in the coming hours and days.
Within the next 12 hours or so the spacecraft is expected to be very busy, and using its thrusters among other equipment. During approach, rendezvous, and docking with the station, the Starliner team will assess spacecraft thruster performance for manual abort scenarios, conduct communication checkouts, test manual and automated navigation, and evaluate life support systems. Crew aboard the station will monitor the spacecraft’s approach and the Starliner crew would command any necessary aborts. In the morning, as Starliner approaches the station we can expect a few important milestones. The spacecraft will autonomously dock to the forward-facing port of the Harmony module. The test objective is to perform hatch opening and closing operations, configure the spacecraft for its time docked to the station, and transfer emergency equipment into the station. During its stay, the crew will evaluate the spacecraft, its displays, and cargo transfer systems. Wilmore and Williams will also go inside Starliner, close the hatch, and demonstrate the spacecraft can perform as a “safe haven”. Once docked, the initial and primary objective of this Starliner launch will be complete.
You then have the final big mission milestone which is reentry. The crew will spend approximately six hours in the spacecraft from undocking until its first landing opportunity. During re-entry to Earth’s atmosphere, the spacecraft will begin to slow down from orbital velocity and the crew could feel loads up to 3.5 g.
Conclusion
Boeing and NASA have found two new leaks in addition to the original helium leak that was discovered before the launch. They have however confirmed that the crew is safe and the mission is continuing on as planned for the time being. We will have to wait and see how it progresses and the impact it has on the space industry.
Hopefully the crew will be safe