Earlier today we finally got another update on Boeing’s Starliner spacecraft in the form of a media teleconference. Here the agency and company revealed that they still aren’t ready to set a return date until they complete more tests related to the thruster malfunctions and the helium leaks which could take weeks. They stressed that the crew is safe and that they are instead just using the time available to them before the eventual undocking.
They specifically mentioned new thruster tests expected to happen in the coming days back at NASA’s White Sands Test Facility. Here I will go more in-depth into the state of Starliner, possible return opportunities, extending its 45-day mission cap, and more.
No Return Date Yet
By now Starliner has been docked to the International Space Station for over 3 weeks, originally docking on June 6th. Leading up to the launch and soon after reaching orbit a combination of helium leaks and thruster failures occurred, and have since been a focus for teams at NASA and Boeing. The mission was set to last about a week at first but then was moved back to a few subsequent dates and has since been undecided. Earlier today they provided more information on the plan and state of the vehicle.
Steve Stich, NASA commercial crew program manager was quoted saying, “Butch and Suni are not stranded in space. Our plan is to continue to return them on Starliner and return them home at the right time. We have a little bit more work to do to get there for the final return” he said.
As far as what work they want to do first, in a statement the agency said, “The integrated Starliner team continues to evaluate the spacecraft’s propulsion system performance and complete other forward work before scheduling undocking from the International Space Station”.
The associate administrator of NASA’s Space Operations Mission Directorate went on to say, “Our goal is to bring Butch and Suni home aboard Boeing’s spacecraft, and we are working to confirm Starliner will perform as designed to return them safely to Earth. Space station gives us the luxury of time, allowing us to look at data we gathered on the way uphill and conduct some additional testing. We’re still in the middle of a test mission, and we want to spend more time with the data before we make the final call to put the crew aboard the spacecraft for return” he said.
In the statement, they clarified that “NASA and Boeing will conduct additional ground testing at White Sands Test Facility in New Mexico to better understand the spacecraft’s thruster performance. This testing will expose Starliner’s thrusters to flight-like pulse counts and thermal conditions for ground teams to inspect and analyze. The data collected also will help determine system improvements for future post-certification missions to station.” In regard to this Stich mentioned that these tests are set to start no earlier than July 2nd and last a couple of weeks. “This will be the real opportunity to examine the thruster just like we had in space on the ground, with detailed inspections,” he said. In other words, its likely going to be weeks until we see Starliner undock and begin its journey home. In theory, this would end up pushing the timeline toward the 45-day cap.
For reference, at the start of the mission it was made clear that Starliner has a 45-day limit at the ISS. That is, this vehicle is only rated for a 45-day stay at the space station. With it docking on the 6th it would mean that Starliner would have until around the 20th of July. However, now it looks like they are trying to extend that 45 day maximum mission duration. In another quote Stich said, “We spent a lot of time working to determine whether we could get meaningful data from a ground hot fire to better inform our decision making in flight, and I am extremely proud of our integrated NASA and Boeing teams for coming up with some innovative options and leveraging testing plans that were already in place for future missions. Based on the continued performance of Starliner while docked, we are working with the station to extend the certification of several components beyond a 45-day mission duration, if needed, so our engineering teams can take the time they need while Butch and Suni support various in-orbit activities that are critical for sustaining station operations and research” he said.
This suggests that they could end up staying at the station for quite a bit longer than originally planned. Stich then said, “We understand that its going to take a little bit longer. We can take our time and get through the crew flight test and have the vehicle return with Butch and Suni, and then we can make decisions afterward.” Focusing back on the state of the vehicle, Mark Nappi, Boeing vice president and commercial crew program manager commented, “We understand these issues for a safe return. But we don’t understand these issues enough yet for us to fix them permanently.
This comes back to the fact that both the Helium leaks and thruster issues have occurred within the Service Module of the Starliner spacecraft. Not long after undocking and before Earth reentry, this will separate from the crew capsule and burn up in the atmosphere. This means that the only time for teams at NASA and Boeing to get data on this system is right now, and the following weeks leading up to reentry.
In a statement going more in-depth the agency said, “Since Starliner’s arrival on June 6 with NASA astronauts Butch Wilmore and Suni Williams aboard, mission teams have been working to complete open work related to managing five small leaks in the spacecraft’s service module helium manifolds while reaffirming the health of the spacecraft’s reaction control system thrusters. Starliner remains available in case of an emergency on the space station that would require the crew to leave orbit immediately and return to Earth.
In addition to monitoring the hardware in orbit, which is operating normally in a docked state, NASA and Boeing continue testing and analysis on the ground by exploring potential causes for the helium system leaks and analyzing instrumentation data on Starliner’s thrusters. Engineers are working to gauge potential helium leak rates that may occur after undocking, validate operational mitigations for use in flight as needed, and explore fault tree considerations beyond what the teams have already gathered from the flight data. They also are evaluating recent ground test results that showed better than expected performance of Starliner’s thruster instrumentation. Based upon these results, engineering teams have confidence that Starliner’s thruster pressure transducers are not overheating in flight and causing premature deselects of the thrusters in orbit, which was initially considered to be a possibility. Meanwhile, simulated propulsion system contingency scenarios continue to be worked in the lab to ensure expected performance of Starliner’s backup systems and thruster combinations for use during the return if needed” they said.
Based on everything said it seems clear that the fact the service module will burn up has added to the complications in testing systems for future Starliner spacecraft. If they could get this exact service module back in one piece after the mission teams would easily be able to investigate and find the exact reason for both the helium and thruster issues. On the bright side, they seem confident that with more time they will figure it out. It also points toward a much longer mission heading possibly into mid to late July.
In a final statement the agency said, “Once all the necessary ground testing and associated data analysis is complete, leaders from NASA’s Commercial Crew and International Space Station Programs and Boeing will conduct an agency-level review. During the review, senior agency leaders and mission managers will discuss their findings and options with the broader NASA community, including international partners, to formally document the agency’s acceptance of Starliner’s flight plan and evaluate future return opportunities.”
In a previous meeting they mentioned that “The crew’s feedback has been overwhelmingly positive, and they know that every bit of learning we do on the Crew Flight Test will improve and sharpen our experience for future crews,” They also clarified that the crew is not pressed for time to leave the station since there are plenty of supplies in orbit, and the station’s schedule is relatively open through mid-August.
Sometime next month, when Starliner does eventually undock, the process requires each system including the service module to work as expected. A few days before the undocking they will power up the vehicle and load cargo onto the spacecraft. On undocking day they will do some leak checks and make sure they are ready to go. The vehicle will depart in mostly an automatic fashion. The crew has one command which is to tell Starlienr it is go to undock. After the undock Starliner is expected to depart much quicker than it rendezvous. It will first go up and above the station then do the departure initiation burn which will send it away from the station. There it will perform an automated hot fire test of the crew module propulsion system. This is followed by a few burns and steps before Earth reentry and landing. Something we can hope to see not too long from now.
Conclusion
Starliner might end up staying at the station for a few more weeks based on the most recent update from the agency and Boeing. Teams want to conduct as many tests as possible before the service module is burned up during Earth reentry. We will have to wait and see how it progresses and the impact it has on the space industry.