Friday, August 18, 2023

SpaceX Shares Views of Booster 9's New Hardware

SpaceX shared some views of Booster 9 with what they refer to as the "vented interstage" to allow hot staging, with two workers on the new hardware that add perspective on the size. 

The hardware is both a heat shield that one worker is sitting on top of and the collar atop the already existing booster with lots of slots left open in it to allow the flames to exit the top and reduce heating of the methane tank, the top tank in Starship.  Another worker is seen with his head and arm sticking through one of those slots just above the front left grid fin.

The interstage adapter looked like this as it was being lifted into place.  

You can see that it's a lot of empty space.  Both images from SpaceX and edited a bit by me to resize and brighten them a bit. 

"Vented interstage and heat shield installed atop Booster 9. Starship and Super Heavy are being upgraded to use a separation method called hot-staging, where Starship's second stage engines will ignite to push the ship away from the booster," the company wrote today (Aug. 18) in a post on X (formerly Twitter) that shared two photos of the new hardware.

"The superhot plasma from the upper-stage engines has gotta go somewhere," Musk told journalist Ashlee Vance in a discussion on X on June 24, during which he revealed the design change. "So we're adding an extension to the booster that is almost all vents, essentially. So that allows the the upper-stage engine plume to go through the sort of vented extension of the booster and not just blow itself up."

This set of pictures makes me lean toward my belief that the road closures on Monday (early next week) are to move B9 back to the Orbital Launch Mount for more testing.  Launch is still "out there" waiting on the FAA and perhaps the lawsuit, but this makes it look like B9 may be considered ready to roll back out to the OLM for follow-on testing.


  1. Photos like this really show the immensity of Starship and Booster.

    Falcon 9 is big. This thing is huge.

    Looking forward to the launch.

    1. Looking forward to the launch. Oh, yeah.

      When they launch the first one from the Cape, I might have to go up to one of the places to get a better look. Haven't done that since the early Shuttle days, a couple before Challenger. Mostly because once the vehicle is up a couple of miles the view isn't terribly different.

  2. I saw hot staging and thought, oh boy, that's gonna be fun. I suppose an advantage is you get to maintain velocity rather than slowing down while the first stage fails away. Though I don't know how much is actually lost.

    I look at an experiment like this that may work, it may not, and know there is absolutely no chance NASA would try it.

    1. The number Elon has mentioned is a 10% improvement. It seems like a lot of effort for a 10% gain, but I'm no rocket scientist. I wasn't aware the Russians have been doing hot staging forever.

    2. I saw the 10% figure as well. That's pretty significant in rocket science, I suppose. I didn't know the Russians were doing it either.

      What's the worst that can happen? What happened last time? Everyone still cheered.

    3. I think the 10% number may not include the extra weight of the interstage. Elon has a tendency to forget to mention the entire picture. The best way it could be stated, imho, would be to quote the percentage increase of payload mass to orbit.

      And yes, the Russians have been doing it forever, with the Proton. Their interstage looks like the kind of lattice one would put under the front porch to keep cats and dogs out.

      In this Soviet design, hot staging eliminates the need for ullage motors to settle the fuel, saving some weight. I'm not sure how Starship was originally going to handle this issue.

    4. If you watch some of the Chinese launches you will also see the interstage webbing as well. Not on all of them, but I noticed the other day they had one of their smaller rockets thusly equipped.

  3. If you look carefully, you will notice the flat spot in the middle is where the three center (sea-level) raptors are. Only the outer (vacuum-level) raptors will fire for interstaging.

    The vac-raps are for orbit anyway, the sea-raps are for landing. Only the sea-raps are electrically gimbaled.