Space X preparing for flight test 11

While there are no potential launch dates being discussed and NextSpaceFlight.com shows nothing more specific than No Earlier Than 2nd Half 2025 (which started in June), SpaceX is still crunching data from Flight Test 10 along with discussing new plans for this next test flight. 

The occasion was the American Astronautical Society's Glenn Space Technology Symposium in Cleveland held Monday, September 8, in Cleveland.  The SpaceX spokesman will probably be familiar to you, Bill Gerstenmaier, SpaceX executive in charge of build and flight reliability.  Gerstenmaier came to SpaceX in 2020 after a career at NASA.  He began his career as an aerospace engineer working on the space shuttles in 1977 - before the first STS mission.  He rose through the ranks at NASA to become head of the agency's human spaceflight programs before joining SpaceX. 

As we've talked about before in FT-10 posts, there were many things being studied, but the most important were the problems with Starship's propulsion and propellant systems that ruined the three previous test flights.  On top of that was data on Starship's heat shield, an array of thousands of tiles covering the ship's belly as it streaks through the atmosphere during reentry.  

"Things went extremely well," Gerstenmaier said.

A little more than an hour after liftoff, the Starship guided itself to a controlled splashdown in the Indian Ocean northwest of Australia. The ship came within 10 feet (3 meters) of its targeted splashdown point, near an inflatable buoy in position to record its final descent.  

Bill Gerstenmaier, SpaceX's vice president of build and flight reliability, discussed the results from Starship Flight 10 on Monday. Credit: American Astronautical Society

Nearly halfway around the world and within 10 feet of the inflated buoy seems like pretty good performance to me.  Yeah, a couple of B-2 bombers that took out Iran's nuclear program were apparently more accurate than that, but they were piloted by well-trained experts, not self-guided. 

"We were essentially doing a test to see if we could get by with non-ceramic tiles, so we put three metal tiles on the side of the ship to see if they would provide adequate heat control, because they would be simpler to manufacture and more durable than the ceramic tiles. It turns out they're not," Gerstenmaier said.

"The metal tiles... didn't work so well," he said. "They oxidized extremely nice in the high oxygen environment. So, that nice orange color, kind of like a [space] shuttle external tank color, maybe paying homage to the shuttle program, was created by those three little metal tiles up on top."

How well the tiles worked is interesting but not that important to folks like us who watch and try to understand.   More importantly, they're a good example of how SpaceX iterates and refines designs.  Metal heat shield tiles aren't a new thing; NASA was working on them when Gerstenmaier hired on there in '77. 

"I think we learned a lot by taking them to flight, and we still had enough protection underneath that they didn't cause a problem," Gerstenmaier said. "In most of the tiles, there are fairly large gaps, and that's where we're seeing the heat get through and get underneath."

A mastery of Starship's heat shield is vital for the future of the program. The heat shield must be durable for Starship to be rapidly reusable.  Musk eyes reflying Starships within 24 hours.

A (stunning) view of SpaceX's Starship rocket shortly before splashing into the Indian Ocean. Credit: SpaceX

Continuing his presentation, Gerstenmaier pointed to a patch of white near the top of Starship's heat shield. This, he said, was caused by heat seeping between gaps in the tiles and eroding the underlying material, a thermal barrier derived from the heat shield on SpaceX's Dragon spacecraft. Technicians also intentionally removed some tiles near Starship's nose to test the vehicle's response.

"It's essentially a white material that sits on Dragon and it ablates away, and when it ablates, it creates this white residue," Gerstenmaier said. "So, what that's showing us is that we're having heat essentially get into that region between the tiles, go underneath the tiles, and this ablative structure is then ablating underneath. So, we learned that we need to seal the tiles." 

An important aspect that's worth remembering is that Starships are made of stainless steel, a "special alloy" (seems to be the common description - I thought I remembered it being a 400 series stainless, but that's not enough detail to do any kind of study).  The Space Shuttles were made of aluminum.  That means the Starships can handle temperatures higher than the Shuttles could without damage.   

[...] SpaceX officials think they have a solution. Near the top of the ship, amid the patch of white, engineers noticed a few darker areas. These are places where SpaceX's ground team installed a new experimental material around and under the tiles.

"We call it crunch wrap," Gerstenmaier said. "It's like a wrapping paper that goes around each tile, and then... these tiles are mechanically held in place. They're snapped in by a robot. When we push the tile in, this little wrapping paper essentially sits around the sides of each one of the tiles, and then we cut it off on the surface."

For flight 11, the mission will be more similar to FT-10 we just had than the big words being thrown around - like "orbital".  Not this time.  We don't have a definite date, but it looks like FT-11 might make it in October and the shift to FT-12 will at least partially depend on well that goes.

"Next year, we step up to another version of both ship and booster, called V3 (Version 3)," Gerstenmaier said. "It also has a new Raptor engine underneath, with more performance than the previous ones.  So we'll fly V3 (suborbital) first, and then if that's successful, then we'll probably go orbital after that with the next V3."

That leans toward predicting an orbital flight no sooner than Flight 13.  Flight 10 was August 26th.  Saying FT-11 might be in October implies something like six to eight weeks between them with FT 12 in November and FT-13 looking to be by the end of the year.  This also matches a recent comment by Musk, who said SpaceX will likely attempt to catch and recover Starship back at Starbase somewhere around Flight 13 to 15, depending on the outcomes of the next couple of test flights.