Please consider donating to Behind the Black, by giving either a one-time contribution or a regular subscription, as outlined in the tip jar below. Your support will allow me to continue covering science and culture as I have for the past twenty years, independent and free from any outside influence.

Regular readers can support Behind The Black with a contribution via Patreon or PayPal. To use Patreon, go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation. For PayPal click one of the following buttons:


Or with a subscription with regular donations from your Paypal or credit card account:


If Patreon or Paypal don't work for you, you can support Behind The Black directly by sending your donation by check, payable to Robert Zimmerman, to

Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652

SpaceX replacing two engines on Starship prototype #9

Capitalism in space: After the static fire engine tests earlier this week, SpaceX has decided to replace two of the Raptor engines in its ninth Starship prototype before moving on to its 50,000 foot test flight.

“Two of the engines need slight repairs, so will be switched out,” SpaceX founder and CEO Elon Musk said via Twitter early this morning (Jan. 15).

Musk did not give a target launch date for SN9. But he did say, in another tweet, that it’s “probably wise” to perform another static fire with the vehicle after the engine swap is complete. So a weekend launch for SN9 seems pretty unlikely.

Makes sense, but I must admit a bit of disappointment. I was really hoping that the next flight would occur on the same day NASA attempts its first static fire test of the core stage of SLS. The contrast would have been edifying.

Personally this delay is great for me, as I will be out in the country caving this entire weekend, and would have missed it if it had occurred during the weekend. I will miss the SLS static fire test, but that will be far less interesting (unless something goes wrong).

Pioneer cover

From the press release: From the moment he is handed a possibility of making the first alien contact, Saunders Maxwell decides he will do it, even if doing so takes him through hell and back.

Unfortunately, that is exactly where that journey takes him.

The vision that Zimmerman paints of vibrant human colonies on the Moon, Mars, the asteroids, and beyond, indomitably fighting the harsh lifeless environment of space to build new societies, captures perfectly the emerging space race we see today.

He also captures in Pioneer the heart of the human spirit, willing to push forward no matter the odds, no matter the cost. It is that spirit that will make the exploration of the heavens possible, forever, into the never-ending future.

Available everywhere for $3.99 (before discount) at amazon, Barnes & Noble, all ebook vendors, or direct from the ebook publisher, ebookit. And if you buy it from ebookit you don't support the big tech companies and I get a bigger cut much sooner.


  • Jim

    Well, the SLS test fire, scheduled to last 8 minutes, lasted a whole 1 minute and a few seconds before shutting down when they tried to test the TVC system. They are still talking like they are going to ship it to the Cape as is. As long as they don’t have to gimbal the engines, they should be “headed for success”.
    Bunch of nuts! Maybe they will change their tune after “looking through the data”. They only said that about 50 times in the few minutes I watched it. They are calling it a “successful test” after only getting through 1/8th of the run and not being able to gimbal the engines at all.

  • MJMJ

    Hey, Jim, just put really big fins on the rocket, that’ll do the trick. Who needs gimbals?

  • Jedi_Squirrel

    So if this was an actual mission then an abort would have initiated, and loss of mission. An abort at T+1 would be fun, aborting while those 2 SRBs are running full bore. Oh, and when they do the “Plugs Out Test” make sure no one is in the capsule.

  • pzatchok

    From what i understand SpaceX is launching off of a flat pad.

    They could put a deflector under the rocket to stop the impulses from coming back up into the engines.

  • Ray Van Dune

    Can’t afford a new keyboard right now, so I’m glad I didn’t have a mouthful of beverage when the NASA spokes-lady signed off with a brave “Go, Artemis!”

    My first thought was “But not likely very far.”

  • Ray Van Dune

    As for launch thrust deflection, as long as we are talking three Raptors clustered close to the centerline, I wonder if a steel cone would do it? A V2 launch deflector on steroids.

  • Michael Schnieders

    “Wow, Dr. Bob!”(Muppet reference), you Really know how to taunt Murphy’s Law.
    Seriously, I am a bit amazed. What critical hardware associated with the main engines could have failed? I find this a bit disconcerting because the Space Shuttle Main Engines are heritage hardware with only one issue (from a gold plug?).

    P.S. I hope you share some of spelunking pictures when you get back.

  • Michael Schnieders

    My understanding regarding Starship is that one of the main design features is to be unaffected by the unprepared surfaces on Mars and the Moon. SpaceX could make their life easier by putting in a deflector shield at the test launch facility, but then they would not be prepared to compensate for debris damage where there is no manual repair capability.

  • Ray Van Dune

    Michael, that is an interesting objective, one that I had not heard stated from Musk, but which makes perfect sense.

    A key component to achieving that goal would seem to be the use of upper-body thrusters as on the Lunar Starship, which I have assumed would also be required for the Mars version.

    So I have tended to regard the current Starships as immediate precursors to a LEO / Circumlunar / P2P version, which would only have to deal with well-prepared Earth surfaces. But a simple concrete pad, only coated with the standard flame trench coating, strikes me as a bit too lightly “well-prepared”.

    Perhaps then first-generation Starships should either be operated on more traditional purpose-built launch / land surfaces, or adopt upper-hull thrusters from the beginning?

Readers: the rules for commenting!


No registration is required. I welcome all opinions, even those that strongly criticize my commentary.


However, name-calling and obscenities will not be tolerated. First time offenders who are new to the site will be warned. Second time offenders or first time offenders who have been here awhile will be suspended for a week. After that, I will ban you. Period.


Note also that first time commenters as well as any comment with more than one link will be placed in moderation for my approval. Be patient, I will get to it.

Leave a Reply

Your email address will not be published. Required fields are marked *