NASA managers say they are close to a decision on when and how they plan to bring Boeing Starliner Crewed Flight test astronauts from the International Space Station. The mission was originally slated to run eight days, but the pair have been in orbit for sixty-three days since their June 5th launch from Cape Canaveral Space Force Station aboard an Atlas V.

“I don’t think we’re too far away from making that call,” Ken Bowersox, NASA’s Associate Administrator for Space Operations Mission Directorate said this afternoon. He added, “We know that at some point we need to bring Butch and Suni home [but] while they’re up there, we have extra crew, we have extra hands, they can do a lot more work, but they’re also using up   more consumables, more supplies.”

Bowersox added that Williams and Wilmore may not return on the Starliner spacecraft. “In the case that we have with the Starliner crew,” he said, “the option to either bring the crew home  on the Starliner or to bring the crew home on another vehicle.  We could take either path, and reasonable people could pick either path depending on where their view is on our position in the uncertainty bound  that we have for the date.”

“We have been working with SpaceX to ensure that they are ready to respond on Crew 9 for a contingency of returning Butch and Suni on Crew 9,” Bowersox said. “If we need that we have set up the [Crew] Dragon for Crew 9 to have flexibility to have only two passengers fly up on that flight.”

One thing that NASA did not disclose is which two of the Crew 9 crew would potentially be taken off the mission should the need arise. “We’re not really ready to share  the data on which crew members,” said Steve Stich. “I think we’ll do that at the appropriate time.”

Why The Uncertainty About Starliner?

The reason for the uncertainty is well-documented: Starliner has thruster problems on its Service Module, and engineers and mission managers within NASA are not unanimous that the spacecraft can be safely flown until such time as the Starliner capsule would separate from its troubled SM and then begin re-entry.

Bowersox said, “We’ve got on the thruster system, on the propulsion system.  Moving forward, what we’re trying to do is reduce that uncertainty, see if we can drive some more consensus, amongst our team  at the same time getting more serious about evaluating our other options.  It’s been really great to watch our team working, our Boeing team, our NASA team, the way people are speaking up; the way we’re hearing different voices, different thoughts on how critical  different  factors are in the decision.”

“I think it’s been very healthy,” Bowersox said, speaking about the debate behind the scenes.  “I have to admit that sometimes when we get this agreement, it’s not fun. It can be painful having those discussions, but it’s what makes us a good organization and it’s what will get us to a good decision as we approach that point here in the future.”

“And I don’t think we’re too far away from making that call.”

Steve Stich Comments On Starliner Issues

Steve Stich, NASA’s Manager for the Commercial Crew Program, gave an in-depth rundown of the technical aspects of Starliner’s issues:

“I’ll talk a little bit more about the manifest changes we’ve made and what we’ve done to give ourselves some flexibility in the near term relative to  all the options that we’re looking at. So, if we start with Starliner last time we talked  a lot about testing results at White Sands, we had completed the thruster testing, which was essentially two uphill [ascent to ISS after launch] profiles trying to get to the temps that we saw on this particular thruster.”

“And then we really have done five downhill [undocking and free flight to reentry] profiles with that particular thruster. We were able to replicate degradation in the thruster during. That testing, and we saw that continually on the downhill side with the thruster thrust levels degrading over time, which seems to mimic what we’re seeing in flight to some extent  during those downhill profiles, as we talked about during that testing, we gained insight into what we think one of the contributing factors are for that thrust degradation.”

Stich continued: “And that would be this Teflon seal on the oxidizer line poppet. Now, this poppet’s really small. It’s about, if you hold up your little pinky finger, it’s about the size of that. A little bit smaller even than your pinky finger. So it’s a small poppet. But what we saw during that testing is the  swelling of that Teflon seal.”

“It kind of extruded a little bit. And what happens with that seal is it blocks the flow into the thruster itself, down into the combustion chamber. So we know that’s happening. We know we can get vaporization when it gets hot in that line, bringing propellant into the thruster.”

“And also when that poppet is blocked by the Teflon seal, we see some cavitation, in other words, unsteady  flow across that poppet.  We have some animation that we hope to be able to release soon to you. So you can see  what this is like. Boeing has been doing a lot of work on that animation.”

“Hopefully, we can have them share that soon so you can get a better idea of that mechanism as well. We also have this same theory that has some vaporization of the propellant, right, and it drops the thrust. So there’s really two key things that we think is happening. One, when the thruster gets really hot, the propellant can vaporize.”

“That’s where we saw the really low thrust readings on docking day. And then as the poppet swells, we can get some blockage there. Based on what we learned at White Sands,  what we’re trying to do now is sort of understand what all that data means to us from the white sands testing and then what it means to the thrusters on orbit.”

 “We did do a hot fire while we’re docked to the International Space Station on Saturday, July 11.   we wanted to understand the performance of all the thrusters across the vehicle. So we hot fired all 27 thrusters. We did not hot fire one thruster in the bottom doghouse.”

“We call it the B1-A3 thruster. That one had really low thrust before, during  the dock when we were docking back on July 6. And so we did not. Or June 6, and we did not hot fire that thruster. The interesting thing when we hot fired the thrusters is all the thrusters now across the whole vehicle are essentially at nominal thrust level.”

“So, for example, the one that we saw the most degradation in the two. A two was at about 80% before the hot fire, and now it’s about 98%. So somehow, if the poppet is the theory of what’s causing the thrust degradation, the blockage in that ox flow, somehow that piece of Teflon must have contracted and is now not blocking the flow like it was.”

“And so we have a nominal flow, essentially, into that. Thruster and nominal thrust. What we’re really trying to do now, that gives us a lot of confidence in the thrusters, but we can’t totally prove with certainty what we’re seeing on orbit is exactly what’s been replicated on the ground.”

“We’re trying to understand a little bit more about the conditions that cause the thruster fail-offs. It’s not always at the same temperature. It’s not always at the same number of pulses. And so we’re trying to understand that we are doing modeling on the ground to try to understand how this Teflon could extrude what the forces are on that Teflon.”

“And then trying to understand how it could contract over time. People really want to understand the physics of  what’s going on relative to  the physics of the Teflon, what’s causing it to heat up, what’s causing it to contract. And that’s really what the team is off trying to understand. And then look ahead toward the downhill phase and the heating on the downhill phase and seeing if we can model that on the downhill phase and ensure we have good thrusters.”

“Again, we have really good knowledge of what the downhill is. But how does that really help us out?”

 “In combination with that, we have tried to buy ourselves a little bit of time to work various options for return. And so recently, this week at the Program Control Board, just yesterday, we approved moving the Crew 9 mission to no earlier than September 24. We took that to the Program Control Board, and it was approved.”

— Steve Stich, August 7, 2024

Stich on Using Starliner As A Rescue Vehicle

“We have been working with SpaceX to ensure that they are ready to respond on Crew 9 for a contingency of returning Butch and Suni on Crew 9 if we need that. We have set up the dragon for Crew 9 to have flexibility to have  only two passengers fly up on that flight,” Stich said.

“And then we could return four crew members in the February 2025 timeframe. And Butch and Suni would remain on station and become part of that increment and return home with them on Crew 9. Now, we haven’t approved this plan. In other words, we’ve done all the work to make sure this plan is there.”

“We have the suits identified to fly up on Crew 9. We have the seats set up so that we can fly multiple complement of people. But we have not turned  that on formally, as that’s the path that we’re going to go down. But we wanted to make sure we had all that flexibility in place.”

“We’ll  fly up the supplies needed on that Crew 9 flight, including any suits needed for butch and Suni.  You know, we’ve done previous work with that for other contingencies.  And we’ll have the foam inserts to work on all the seats for the various crew members.”

“So we’ve done a lot of contingency work and a lot of contingency planning for a lot of scenarios, but we think now we would have the whole waterfront covered. As I said, we haven’t really implemented planning for the mission for these things, but we have all the items in place to keep all the options on the table.”

That said, it appears that NASA is keeping its options open by thoroughly investigating and completing at least preliminary plans for the option of returning the Boeing Starliner CFT astronauts on a SpaceX Crew Dragon.

At the end of the press conference several things were clear: first, that NASA is undecided on whether to return Wilmore and Williams to Earth using Starliner, second, that there are disagreements within NASA about doing that, and third, that returning on a SpaceX Crew Dragon is a very real possibility with planning already started for that option as a contingency.