Listen in as former Space Shuttle program manager Wayne Hale joins Aviation Week's Irene Klotz and Guy Norris to unpack Starship's third flight test.

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Transcript

Irene Klotz:

Welcome to this week's Check 6 Podcast. I'm Irene Klotz, Aviation Week's senior space editor. And I'm here with senior editor and propulsion guru Guy Norris. And a very special guest, Wayne Hale, a former NASA senior manager who recently retired as Director of Human Space Flight with Special Aerospace Services. Welcome to you both. We're here today to talk about the Starship program. On March 14th, SpaceX conducted the third integrated flight test of the Starship super heavy system, which is designed to transport massive amounts of cargo and eventually people safely, reliably and inexpensively into orbit and beyond. Wayne, I'd like to start with you. That sounds a lot like the promise of the Space Shuttle program back in the early '80s. What's different this time?

Wayne Hale:

Well, I think one of the key differences this time is it's being done privately. It's not a government project. I mean, yes, it's integrated into the Artemis NASA Lunar landing program, but it's really being done by SpaceX, Elon Musk and his brilliant team of innovative engineers. And not only is it being run from a different kind of perspective like that, but it's using advances in technology that we didn't have 40 years ago when the Space Shuttle was being designed. So we will watch to see if they're more successful in the rapid turnaround and economic turnaround of a reusable vehicle than the Space Shuttle was. I certainly hope they will be. But the jury will be out until they actually refurbish one and we'll see how that goes. But it does have the possibility of being a true game changer, just as the SpaceX Falcon 9 has been a game changer for the commercial launch industry, with much lower prices and much higher frequency of launches. So we'll see how Starship proves out over the next few years.

Irene Klotz:

Guy, what caught your eye about flight test three and what do you think will be on tap for flight test four, which apparently may be as soon as early May?

Guy Norris:

Yeah. Thanks, Irene. I think, well, first of all, I still can't get over the sheer scale of what we're seeing with Starship and the whole system. The startup of those 33 Raptor engines on the booster stage, all went flawlessly with liftoff. So every time they do this next test, they get further. SpaceX proves more. But what really got me about this was the beautiful video, the downlinking, which they used using their Starlink system. Which enabled unprecedented video as well as data coverage of particularly the coasting phase of Starship. And the fact that for the very first time, as far as I'm aware, and Wayne maybe could correct me on this, you could get that amazing footage of the plasma building up as the Starship passed the von Kármán line at around 100 kilometers and essentially began to hit the Earth's sensible atmosphere. So I mean, there's so many areas to unpack here. But anyway, that's my opening thoughts. It's just amazing scale and the incredible footage that we saw.

Irene Klotz:

Well, spoiler alert, sneak peek, that's our cover for next week Av Week is the reentry shot. Wayne, is there any use for that from an operations perspective to get that kind of view of a hypersonic reentry?

Wayne Hale:

Well, of course there is. We did attempt similar things during the Space Shuttle program. On Columbia, we had put cameras in the tip of the tail in a pod that was called the SILTS pod, Shuttle Infrared Leeside Temperature Sensing, and got some amazing footage. Not in real time, but after it landed and we recovered the data of the plasma trail. And of course we also took a lot of ground and aircraft-based footage of the Shuttle during reentry. And all of those things are very helpful. It's very hard to simulate a hypersonic flight in wind tunnels. They're very limited in hypersonics. And the computational fluid mechanics, which is the mathematical way to analyze hypersonic flight, is not well understood. So any data that's gained about how the shock waves interact or the thermal processes is hugely important. And I suppose people are studying very hard on all that video that came from the Starship early reentry to see how it worked. So from a hypersonic engineering standpoint, it's huge. Yes.

Irene Klotz:

Guy, considering the flight test program, how quickly do you think it will be that Starship becomes operational based on what we've seen so far?

Guy Norris:

Oh boy, Irene, what a question. Well, when you think about it, it's remarkable how quickly, even in the first three test flights, how much progress we've seen made. If you look back at the history of SpaceX, they were on the verge of obviously collapse when the original Falcon 1 series, they were literally right on the edge of it. I think we're talking obviously about a far different situation now because the company is so well-founded, it's got vastly more resources. So I think they've got this ability to see this through. We should point out though, obviously doing a quick back of the envelope calculation. There's 39 engines on the full stack on each flight. So there's 117 Raptors being deep-sixed so far in this test program. So it's not inexpensive, obviously. I think they do have the chops obviously to carry on with that.

But given the rate of progress, I wouldn't be surprised if we're seeing successful recoveries of that booster stage, maybe by the two or three more flights perhaps. As for Starship, I think that's perhaps more of a difficult solution really, if you know what I mean. One of the things that I noticed was that obviously during that coast phase, the attitude of the vehicle seemed difficult to control. And you could see that during reentry, obviously the vehicle was rolling significantly. The Starship actually began to face side on in a sort of a retrograde position. And there's all sorts of implications, as Wayne would attest to, to a vehicle reentering badly in that case. Obviously the structure was weakened, the body flaps slowly began to correct for the roll, and it brought the S28, which was the name of that Starship, almost to the correct orientation. But the aft end of it, where the delicate parts are, where the engines were exposed, began to point into the airflow for several seconds. And obviously that's when the plasma began to really compromise the vehicle.

So I think one of the big issues is going to be really the flight control system really. And really doing something with the reaction control system. There has to be a lot of thought going into how do you improve that going back into reentry. Because you have to get the spaceship, the Starship has to be into that belly flop maneuver, which is obviously the unique aspect about this. That entire one side of the vehicle was prepared for reentry with that thermal protection. But it wasn't really tested because the attitude was all wrong when it went into that. So I think getting the Starship correctly oriented for reentry is the key for the next test. It must be remembered though, which is amazing that despite all of that, being in the wrong position, it did survive, until we lost coverage, for at least five minutes going through that awful environment.

So it says a lot for the basic robustness of the vehicle and how it got all the way down to at least 65 kilometers, maybe more, before, we don't know really what happened at the very end. So I think from the Starship perspective, there's still a lot to look at. From the booster perspective. That's another area where there's such a lot going on. You remember when it was completed, it did successfully complete the boost back burn, which was a great sign. But then there was this weird asymmetric engine shutdown kind of issue. Was that deliberate? Probably not. We just don't know yet enough from SpaceX. But then it successfully reoriented itself for entry. And it's using these cold gas thrusters which are fed with residual ullage gas from the tanks. And you began to see the four grid fins actuating. And these grid fins, by the way, each weigh, I believe, 6,600 pounds each. I think that's enormous, isn't it?

So we're not talking about insignificant structural units here or control systems. We could see them begin to operate from the onboard cameras. And what we saw was quite a lot of movement from them. And whether this was a deliberate part of flight testing, checking the actuators, the flight control mechanism to see how they were responding or whether it was actually the vehicle itself attempting desperately to correct its orientation. Again, we don't know. Of course, as it descended further into the atmosphere, that effect was more and more pronounced because it's the more sensible atmosphere. So obviously the whole booster began this severe oscillation. We don't think at that point it was any more testing of flight dynamics or flight control software. I think it was essentially out of maneuver room at that point. So the landing burn started pretty late, from what we know, just over a kilometer, still traveling multiple Mach numbers. But only three of the 13 engines re-lit. And two of those were then shut down, leaving only a single engine still burning according to the telemetry.

SpaceX had specifically said that we're going to use all 13, those are the gimbaled engines in the center there, for the deceleration, and then reduce that to only three for the last part of the soft touchdown into the water. So obviously then the booster exploded at around 1,000 feet or thereabouts. So vehicle motion itself I think could have caused the engine restart problem. So that's another area where, for the next flight test, they're going to have to really focus on controlling the way that they've actually really focusing on an engine restart and the situation they've got there. So yeah, as I say, a lot to unpack really.

Wayne Hale:

If I could add just a little bit to what Guy pointed out. Going back to the production phase, SpaceX is turning out one of those huge Raptor engines a day, which is unbelievable production. Usually it takes weeks to months to produce an engine of that size and they're turning out one a day. So they've got to figure out, I think, how to improve those engines to make the restart more reliable because clearly that's been a problem, restarting. They seem to have gotten them to where they will work for the entire boost phase, which if you go back to the first test flight, there were several that didn't work for the entire boost phase, much less restart. And so they're incrementally edging up.

I worked in the government programs for many years and I have to say the SpaceX way of testing is completely different. I mean, if we in the government, using the taxpayer's money, had blown up three rockets in a row, our program, oh well, we would've never gotten that far. I mean it would've been cut off at the knees. So this is a different way to do things. And you get in these debates about pros and cons. One of the things that did bother me a little bit about this third flight, I've been watching some of the reports out of South Texas, and people are picking up the re-entry heat tiles off the beach. And I don't care what orientation you're in, if you don't have those heat-resistant tiles, you are not going to survive reentry.

We did a lot of studies and vehicle breakup normally occurs around 210,000 feet, which is, I don't know, 55 or so nautical miles high on an unprotected vehicle. And so this one, we don't know exactly when it broke up, but clearly it was in that ballpark. And so perhaps it was due to not being oriented the right way, perhaps it was due to too many missing tiles. So if you recall the Shuttle program, we worked very hard to make sure the tiles wouldn't fall off. And early on, that was a huge problem in the development was making sure the heat tiles stayed on. SpaceX has got to work on that problem.

In terms of when will they be operational. It's hard to say. I don't care who's making a projection it is probably wrong. We see this all the time in aerospace. People make projections about when their system is going to fly or be operational, and it just always seems to take longer. SpaceX is on the clock here to support NASA's Artemis moon landing. And that's a very aggressive schedule to get to an operational state where they can launch, I don't know, half a dozen to a dozen of these rockets in a very short amount of time that fill up a tanker that can send a lunar lander to the moon.

And it is going to be very interesting to see how long it actually takes. Because the clock is ticking and there's a lot of incremental improvements, I would say major improvements, that have to be made to meet that milestone. Of course, always remembering that Elon's interest is in Mars and the Starship really is aimed toward Mars missions. And to use it for a lunar mission is to take it on a different path than the original design intent, which brings in a lot of questions. So while it is truly a remarkable vehicle and has demonstrated incremental improvement on every test flight, they've got a long way to go.

Irene Klotz:

So speaking of questions, Wayne, one of your last positions at NASA was strategic partnerships. And one of the things with SpaceX in particular that raises the question of what is the role of private industry in the midst of a taxpayer supported civilian space program? It's one thing to have SpaceX be a contractor and provide a service. It's quite another when a company gets beyond where the US government is in a policy, say, SpaceX wanted to skip the moon and go to Mars. Where do you see that playing out? And what do you see the future role of NASA is when more technical capabilities and efficiencies are in private hands now rather than the government?

Wayne Hale:

I think private industry can be much more efficient, much more nimble in developing new systems and actually bringing them to operation than a government system. We were covered over with very detailed and onerous requirements and mandates to make a government owned vehicle fly. And I think the success of the commercial cargo resupply of the International Space Station and the commercial crew transportation system to the International Space Station have proven out that buying services can save the taxpayer's money and actually provide a good, useful product in a shorter, if not the same amount of time, but probably shorter amount of time. My experience after spending 32 years in the government and then another dozen in private industry is that it would be great if the space program could get away from the politicians.

As long as you're tied up... And we just saw this. We just saw the president's budget request go in for next year. It competes with so many other priorities that the federal government has and there's never quite enough money to do things that NASA would like to do. I'm heartbroken over the idea that they're going to mothball the Chandra X-ray telescope because they whacked the money or the OMB or somebody whacked the money out of the budget. But if we can get on a commercial basis where you actually can make a profit and companies then invest more money apart from the federal government, then it's a virtuous cycle. And I suspect that the future lies in the hands of private industry and not as it was back in the 1950s or '60s with big government contractors.

Guy Norris:

There was one other aspect of the mission which I thought was interesting, which was their attempt to demonstrate this Pez door, which was a payload dispenser door that they tried to, well, they did open, but perhaps only partially. And there was an indication, if you look closely at the video, that there was still some atmosphere really inside the vehicle at that point. There was some hazy clouds floating around. So we're interested to perhaps look at how that's going to play out in the next test because obviously you don't want even a partial atmosphere still retained in area where it's supposed to be zero atmosphere.

So one of the things that interested me about that was that the same thing apparently happened on the early days of the Shuttle where there was still some retained pressure inside. And when they tried to open, initially anyway, the payload doors on the Shuttle, there was some initial issues there where they had to do some clever things with releasing that partially trapped atmosphere inside. So anyway, that's just one other aspect where, again, they're going to have to really get down to business, I think.

Wayne Hale:

Yeah, Guy, I'm going to have to go back. We didn't have problems with trapped residual pressure, but we did have alignment problems with the latches and the mechanism that opened and closed the door. So that took a little bit of working out. I'm more interested in the cryogenic propellant transfer experiment that they apparently did. I haven't heard any results. That's going to be key for the future.

Irene Klotz:

I'm afraid that's all we have time for. This is a wrap for this week's Check 6 Podcast. Thanks to our podcast producer in London, Guy Ferneyhough. Don't miss the next episode by subscribing to Check 6 in your podcast app of choice. And one last request, if you're listening to us in Apple Podcasts and want to support this, please leave us a star rating or a review. Thanks very much.