What Starhopper achieved

My annual birthday-month fund-raising drive for Behind the Black is now on-going. Not only do your donations help pay my bills, they give me the freedom to speak honestly about science and culture, instead of being forced to write it as others demand.


Please consider donating by giving either a one-time contribution or a regular subscription, as outlined in the tip jar below.


Regular readers can support Behind The Black with a contribution via paypal:

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

If Paypal doesn'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


You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage. And if you buy the books through the ebookit links, I get a larger cut and I get it sooner.

Starhopper in flight
Click for full image.

Captalism in space: While most news reports (including mine yesterday) have focused on the spectacular 150-meter flight of Starhopper, the real story here is the Raptor engine. As one of my readers said most succinctly in a comment:

As impressive as the flight was, there is so much more going on here. This is the most efficient rocket engine ever, with all fuel and LOX running through the combustion chamber – including exhaust from the turbopumps. The Russians tried it, and NASA tried it, but this is the first time such a design has flown. It’s also the first major engine using methane, so SpaceX is learning all the ground support processes for storing, fueling, and detanking methane (mostly) safely. (Still causing grass fires at launch…) They’re aiming for production cost below $2M per Raptor, and they’re about ready to go full production on the engines, around 500 engines per year.

In fact, Musk himself reveals the truth of Diane Wilson’s comment in a tweet, found in this news story about yesterday’s flight:

Starhopper’s flying days may be done, but the stubby prototype will be retasked rather than put out to pasture.

“Yes, last flight for Hopper. If all goes well, it will become a vertical test stand for Raptor,” Musk said via Twitter on Saturday.

In a sense, yesterday’s flight was no different. Starhopper was essentially a flying test stand for Raptor, which is in itself an incredible concept, when you think about it. Now it will continue to be used as a test stand, but will no longer fly.

I have been told by rocket engineers more than once that you need to build and test your engine before you can really start your rocket design. Once you know its capabilities you can then design and construct the rocket.

This is why Virgin Galactic’s SpaceShipTwo has generally been a failure. They built the ship before the engine, and when the engine had issues they had to improvise redesigns that have limited the ship’s capability and seriously delayed its launch.

SpaceX now has its engine ready. Construction on its two prototype Starships, in Boca Chica and Florida, will now proceed quickly. Based on how quickly it took SpaceX to do the first Starhopper test flights (announced in late 2018 and flying in about eight months), expect test flights within six to eight months. (Note that in this last link I expressed doubt they could get those Starhopper flights off in 2019. SpaceX proved me wrong.)

Finally, a minor news note: SpaceX today successfully brought a Dragon cargo capsule back to Earth after a month at ISS, completing its third flight in space. That this multi-use flight is hardly mentioned in the news illustrates how far SpaceX has reshaped space engineering in only a few years.



  • Scott M.

    Bob, how much of an impact do you think this visible success will have on Blue Origin’s business?

    If we believe Wikipedia, their BE-4 has been in development since 2011. That’s a few years after SpaceX started on the Raptor (2009), so perhaps it’s understandable that they’re lagging behind. Still, they’re just now getting to full power on the test stand.

    On top of that, they’ve ‘only’ flown suborbital flights, on a very leisurely schedule. They’re still at least a year and a half away from flying New Glenn. Given the teething troubles SpaceX had with the Falcon 1, I wouldn’t be surprised if it takes 2-3 tries until NG is successfully flying.

    If I was a potential BO customer, I would be pretty leery of what seems to be a lack of impetus on their part, especially in light of the fact that their main commercial rival is already flying a similar engine and building two flight testbeds.

  • Diane Wilson

    BO’s business case is in two parts. First, they are selling BE-4 engines to ULA, two per Vulcan rocket. ULA will also have a learning curve with methane; it’s not like RP-1. Methane is gaseous and flammable at ambient temperatures. It is much more of a fire hazard, as SpaceX has learned.

    Second, New Glenn will have teething problems. New fuel (methane, again) with different issues from BE-3’s hydrogen/LOX fuel on New Shepard. Bigger rocket than New Shepard. Orbital, needs global tracking, new ground ops – lots of stuff to learn and lots that has to go right. BO could benefit from a successful demonstration flight before flying commercial payloads. They are the new kid on the block.

  • Diane Wilson

    Bob, thanks for the quote, the compliment, and the hat tip!

  • Scott M: Your thoughts on Blue Origin mirror my own, that I have been noting recently. They are taking too long to get anything done, which does not reflect well on them, especially when compared with SpaceX’s pace.

Leave a Reply

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