18 thoughts on “SpaceX is Now Building A Raptor Engine A Day”

  1. The interesting stuff is on page 2:

    “After this initial test flight, Kirasich said NASA is tracking three additional flight tests of Starship for fueling demonstrations. The second test, Kirasich said, will entail a tank-to-tank transfer of propellant, followed by a Starship-to-Starship transfer of propellant, to a complete fueling of Starship from a depot and a long-duration flight to mimic the in-space time of a lunar mission.

    SpaceX plans to keep its low-Earth orbit propellant depots topped off with fuel for missions other than Artemis, Kirasich added. “So it’s not like every time we go to the Moon we’re going to start with an empty depot,” he said.”

    1. SpaceX has a separate contract to demonstate pump 10 tons of fuel from one tank to another in the same vehicle in zero gee. I don’t know why this contract exists, but I think it was due to contract bidding rules. It’s something OldSpace could try for, if they wanted…

  4. The revelations in the Berger article also explain the appearance of two Starship prototypes – S27 and S28 – lacking TPS tiles and flaps. They will be prototype depot ships.

      1. What goes up doesn’t have to come down

        Speaking of which, will the Depot and HLS ships have 6 vacuum Raptors? Instead of the 3 and 3 set between vac and atmo engines. Though I question if that will change the interface to super heavy. The longer vac engines will interfere with structure where the atmo engines are placed.

      2. Not promptly at any rate. A depot ship in LEO would be just another long-life satellite, only to be de-orbited when no longer useful/functional.

  6. My wife included a lot of information on Raptor in a propulsion course she teaches, stuff I hadn’t even seen before. That is the most remarkable rocket engine I have ever seen. Just the feed system is awe-inspiring, and the chamber and nozzle technology blows anything NASA ever came up with out of the water. That they are able to turn out one a day is mind-blowing.

    I do have to take issue with this statement: “…{T]these engines will need to re-light successfully on the surface of the Moon to carry astronauts back to orbit inside Starship. If the engines fail, the astronauts will probably die.” The Starship lunar lander is designed to have a lunar down mass of 100 tonnes. That gives a lot of survival capability (provided the failure itself wasn’t catastrophic). Heck, they would be able to carry an Orion capsule on an upgraded Service Module, and do a direct ascent return to Earth.

    1. Heck, they would be able to carry an Orion capsule on an upgraded Service Module, and do a direct ascent return to Earth.

      Ssssh! Don’t give them any ideas… Leave Orion at the toll both as Starship erm, I mean Artemis, does a TEI to LEO.

    2. There’s also the little matter that the main engines in the tail won’t be used for initial ascent any more than they will for final descent. Both chores will be jobs for that ring of high-pockets landing engines just below the payload-crew section. There will be a lot of them. If they are able to draw on the main tankage, they might even be able to assist or do the entire ascent back to NRHO if some or even all of the mains fail to restart when called upon.

      I hope we learn more about these landing/ascent engines before too long. They may well already be a thing in at least prototype form. NSF’s McGregor-watchers have heard a few mysterious tests recently that don’t sound like Super Dracos, Merlins or Raptors.

    3. Raptor is the most advanced engine ever put into production. The Russians built a working FFSC engine, but never used it for anything. There was a US powerhead demo, but no actual engine until Raptor.

  8. As far as lunar redundancy, Lunar Starship has 6 engines (3ea Vac and SL), but only requires two for ascent (1ea vac and SL). One scenario is to put all six into the start box and then pick two that you know will start. Then you lift off with the waist thrusters, and hit start at altitude. If something goes wrong, you got more engines ready to go. The odds you won’t find two that work are small,

    I do not know if the waist thrusters can handle the full ascent (there’s a theory they will be hot gas thrusters). If not, since they’re running, you can always just land again and try to fix the problem. NASA has noted part of the plan to to carry enough supplies to wait for rescue.

    1. I think the ring of small thrusters at the top is supposed to perform the lift-off to prevent the Raptors from digging a hole or/fodding themselves to death.

      I think they want an improved landing pad before they touch down or lift off using the raptors.

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