photo: NASA
No Return Date Set, Readiness Review May Come Late Next Week
NASA’s Steve Stich and Boeing’s Mark Nappi provided an update on the Boeing Starliner CFT flight today in a teleconference. They stated that while no return date has been set for astronauts Butch Wilmore and Suni Williams to return aboard the spacecraft, the agency and Boeing are relatively close to a Readiness Review that must be conducted prior to Starliner undocking from ISS and returning to Earth. According to NASA, that review may come as soon as the end of next week — or August 2, 2024.
“I think we’re starting to close in on those final pieces of the flight rationale to make sure that we can come home safely,” said Steve Stich.
Below are in-depth comments given by Stich and Nappi.
Addressing Returning On SpaceX Crew Dragon
Steve Stich was asked what the backup plan was if Williams and Wilmore could not return on Starliner. “Obviously, the luxury in our program today, and we’ve never really had this option in other NASA programs, is we have two different systems that we’re flying,” Stich replied. “Obviously, the backup option is to use a different system. I would rather not go into all those details until we get to that time, if we ever get to that time on what we plan to do.
“The beauty of having Dragon and Starliner in two different diverse space transportation systems is we can kind of use those as backups someday. Starliner could be a backup to a Dragon mission, and we’ve looked at all kinds of different contingencies for that. You’ve seen the Russians send up an empty Soyuz, right, to return a crew when they had a coolant leak.”
“I think the beauty of what we have in commercial crew is two different systems, and we would employ those systems if we need to, but we really have our team focused on as we close in on this final flight rationale: returning, uh, Butch and Suni on Starliner,” said Stich
When asked to clarify his remarks, Stich said, “Our prime option is to complete the mission. There is a lot of good reasons to complete this mission, and bring Butch and Suni home on Starliner. Starliner was designed as a spacecraft to have the crew in the cockpit. The crew is integral to the spacecraft.”
Photo: NASA
He added, “There’s a lot of objectives for the flight: having Butch and Suni on board during the deorbit burn and during the entry. Understanding how they monitor the system, how they work with the seat suit interface for landing, getting suited up in the vehicle. And then there’s a whole process of landing and recovery team that we really want to demonstrate before we get into [the] Starliner-1 mission.”
That said, Stich did not specifically rule out using Crew Dragon as a rescue vehicle, but he did make it clear that the current plan is to use Starliner to return the astronauts to Earth after a Readiness Review is completed.
NASA’s Steve Stich’s Comments
“We don’t have a major announcement today relative to a return date,” NASA’s program manager for NASA’s Commercial Crew Program said today at the opening of the press conference. He added, “We’re making great progress, but we’re just not quite ready to do that.”
Photo: from NASA livestream
Later, Stich added, “We’ll work to execute an agency review as soon as we’re ready to do that. That could be as early as late next week. We are following the data and we’ll schedule that review when we need to, and then after that, we’ll set the undock time.”
Parsing Stich’s comments, it is important to note that the agency review could be as soon as next week, but may be delayed further as mission managers and engineers review data from both the Crewed Flight Test Starliner in orbit — “Calypso” — and testing being conducted on the ground in New Mexico.
“I’ve said before, the key attributes of the flight rationale, really, are that we understand the helium leaks, we understand the stability of the leaks, and how we can manage those should they get bigger,” Stich said.
Stich also said that, “We have a criteria in place that we have established, a leak rate that will check before undock and verify that system is good to go.”
A test of Calypso’s thrusters will also be conducted this weekend, while the spacecraft remains docked to ISS. “The hot fire test this weekend will give us confidence in all the thrusters,” Stich said. “Then [we will have] the understanding coming out of White Sands relative to what that testing means and how it applies to the rest of the thruster system.”
Essentially, it sounds like Boeing and NASA will compare ground tests from White Sands to the results they get from Calypso while it is in orbit.
Stich gave further detail. “Really, it’s about the key use of the thrusters for the deorbit burn; that’s the next time we use them. We know the thermal environment is less for the deorbit burn. We know the stressing cases on the thrusters are less.”
Stich concluded his opening remarks by saying “That’s really, I think, the final pieces of the flight rationale that we need to put together. The team is doing great. The joint Boeing and NASA team is doing well. They’re working side by side with each other every day.”
Boeing’s Mark Nappi’s Comments
Nappi is the vice president and program manager of Boeing’s Commercial Crew Program. He leads the development, flight test, certification and missions of the Boeing Crew Space Transportation (CST)-100 Starliner system.
Nappi opened his comments in today’s press conference by saying, “Last time we talked to you, we had 33 actions to complete in order to get to a place wherewe thought we had a good vehicle to come home and we could learn something about the root cause [of the thruster problems.] Of course, the long pull to those actions was all the testing at White Sands that Steve [Stich] talked about. At the time, we believed we had thrusters that were healthy, and we concluded we were good for emergency return.”
Photo: NASA, from their livestream.
Nappi then went into further detail. “Remember, we said we did not have root cause and know what it was going to take to fix it permanently. So, we said, let’s take the time, let’s figure this out. Let’s run this testing at White Sands. If there’s anything more we can do after that testing while we’re docked to ISS, let’s take advantage of that, and then we’ll come home.”
“I think the plan has played out really well. In addition, it’s given us additional confidence to undock and return, and we have a little bit more work to do, as Steve has outlined.”
Nappi Gives A Thorough Breakdown Of Recent Activities
The following is a breakdown of Starliner’s status and testing that Mark Nappi provided today. While it is lengthy, readers may find it worthwhile to read in order to understand what has been done and what the current status of the spacecraft is.
“First of all, let’s start with the helium system. We have a service module at White Sands that was exposed to propellant. And it’s been exposed for about three years. So it was a really good test case to go and do some leak checks on and then take that hardware apart.”
“We did those leak checks. We found leaks. Of cours it’s been exposed to NTO [nitrogen tetroxide] for quite a while. We took the hardware apart, and we found pretty good degradation of the seals, which indicated that they had been exposed to NTO and degraded. So that was a really, really good data point, both from the standpoint of finding out that it had degraded seals.”
“But also we could capture a leak rate, which could end up being our worst case kind of leak rate, because this hardware was exposed for so long. On the second part of the testing, of course, was the thruster testing. Steve outlined that testing, but it was very stressful testing of that thruster through ATP uphill and approach and docking, some increased temperature profiles, um, and some very stressful downhill runs.”
“So all of that was done with the thruster, very heavily instrumented, which gave us a lot of. Information. From that information, and, of course, from the inspections after the test, we’ve determined two things. One is that there’s some Teflon from a seal where the NTO enters the thruster, and that seal was eroded.”
“And when we looked downstream from that seal, we found that material was lodged in a downstream filter. That is where the NTO goes through. Obviously, that restricts flow of NTO and may be part of the cause of the degradation that we’ve seen in flight. The bigger finding was where the NTO goes through a port, to where it gets to the injector inside the thruster, and there’s a poppet that opens and closes and allows that nto to go through at the end of that poppet.”
“Very small poppet. It’s similar to the small inflation valve that you have on a car tire or a bike tire. That poppet has a Teflon seal at the end of it through the heating and the natural vacuum that occurs with the thruster firing. That poppet seal was deformed and actually bulged out a little bit, and again, was an indication that it’s restricting the nto from going through the system.
“So, again, a really good finding. When we looked at the information, we looked at the data, it really does replicate well what we’re seeing in flight. So we think these findings are very significant and are likely the root cause. Obviously, knowing root cause is what gets us to permanent fixes.”
“So there’s very strong evidence, and we’re going to continue to take that hardware apart so that we can finally prove this. Today we’re performing the final hardware inspections, and we’re doing some flow analysis through that type of valve arrangement where we have Teflon in the seal or, excuse me, Teflon in the filter, and this bulging of the Teflon at the end of the poppet.”
“And we’d like to see if we can model this restriction of NTO and recreate what we’re seeing in flight. With all these test results we determined that we could run one more set of tests while we’re docked, and it’s really icing on the cake for us.”
“So, Steve talked about the one more docked hot fire test that’s going to verify all the thrusters are acceptable at the acceptable performance levels. Again, we learned something from this flight. We didn’t know that other visiting vehicles do this before they leave. And so we’re probably going to make that part of our normal regime when we are doing long duration missions.”
“Also, we’re going to do the helium manifold leak checks again. That will give us some data points on how stable the leaks are and assure there’s no additional NTO degradation. Lastly we have a very valuable guidance, navigation and control integrated performance model that was incorporating failures to answer the question, what if we’re wrong on some of these?”
“So they ran over 300 cases. And of all those cases, the results were either green, that we could return home safely or were determined to be not credible, or they had operational controls that could be applied to make sure that we returned home safely. So what’s next?”
“We’re going to share the data and flight rationale with the mission management team. We have one more meeting tomorrow to do that. We’ll use the weekend if required. We’re going to perform the stocking tests that we’ve described and then of course, there’ll be more reviews.”
“We’ll bring the complete story to the agency for the undock review sometime next week, like Steve has outlined and then we’ll be ready to execute the last part of the mission. The last several weeks have been really helpful to understand the helium and thruster anomalies and how to address these problems for future flights.”
“That’s been the real goal here is to be able to address future flights and to gain the confidence that we needed for this mission. Weneed to take the time to get the community all this information and get back to completing the CFT mission. Our mission was to get the crew to ISS.”
“That’s been completed. Our mission was to learn from a flight test. A lot of the learning that we’ve achieved so far really, in my opinion, could only be achieved through the flight test. And now it’s time to get on with returning the crew safely. And there’s that step left to go.”
