August 4, 2026 Quick space links
Since BtB’s stringer Jay is unavailable due to work, there are not a lot of quick links today. This post is also an open thread. I welcome my readers to post any comments or additional links relating to any space issues, even if unrelated to the links below.
- Rocketdyne is now a stand-along rocket engine company again
Aerojet-Rocketdyne was purchased by L3Harris. The Rocketdyne engine division was separated out when a private equity firm took majority control.
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The article said that L3Harris retains the RS-25 engine, and some solid rocket motors. Strange but way above my pay grade.
Not so strange. L3Harris is a long-time defense contractor so small solid motors for tactical missiles is a good fit and, given recent wartime demonstrations of the US’s insufficiency in production infrastructure and inventory of such things, there is no end of new business to be had from the War Dept. Keeping that part of the erstwhile Aerojet-Rocketdyne was a no-brainer.
Keeping the insane $160 million-per-unit contract with NASA for new, expendable RS-25s for SLS is also a no-brainer. At least one full set of four of these will be needed for Artemis 5 and it’s possible that SLSes to launch Artemis 6 and 7 might be in the offing as well. There’s a lot of money to be made here for at least awhile. If that particular gravy train stops a few years hence, the money will already be banked and the RS-25 division can simply be liquidated.
The part of the erstwhile AJR partially spun off to AEI as the “new” Rocketdyne is a less-good fit with L3Harris’s other operations. AEI seems likely to be able to do more with it than L3Harris would – hence the deal.
Solids are an evergreen as long as there are munitions.
Rocketdyne, under this new arrangement, isn’t exactly “stand-alone.” It’s more like ULA, a company with two owners. Unlike ULA, the owners are not equal partners. The majority owner will run things and the minority partner is mainly along for the ride and will simply share, proportionally, in any value appreciation.
Given that AEI’s portfolio also includes Firefly, one possible downstream outcome of this deal could be development of a high-energy hydrolox upper stage for Eclipse/Antares using the RL-10. Firefly might also be better positioned to develop an even larger, post-Eclipse vehicle, given Rocketdyne’s large engine heritage, though few, if any, of the people embodying that heritage are likely still around. It also seems unlikely Rocketdyne can teach Firefly anything about producing engines economically.
No, but maybe Firefly can get RS-25 cost down if given a chance.
RS-68 was simpler than the SSME….I think there were some studies that looked at methane.
Energiya used RD-0120s with channel wall cooling.
Stoke isn’t afraid of hydrogen like Musk is.
Aerojet LR87 and sons used a mix of propellants and did a Glushko with multiple combustion chambers.
That I know of–no one ever used multiple chambers each with its own baffles like F-1 had:
http://heroicrelics.org/info/f-1/f-1-injector-baffles.html
–and channel wall:
https://www.sciencedirect.com/science/article/abs/pii/S0094576520302824
Firefly won’t have any chance to get the cost of new RS-25s down because the part of AJR its major owner, AEI, bought from L3Harris does not include the RS-25 contract. The RS-25, in any case – and at whatever cost – is yesterday’s news and has too limited a future to be worth Firefly’s time.
The RS-68 certainly was simpler than the SSME. It wasn’t a staged-combustion engine to start with and used an ablatively-cooled nozzle and radiatively-cooled bell. That last bit is why RS-68s were not clusterable as was originally intended for the Ares 5. Get them too close together and they melt each other.
Too bad those notional “studies” of methane and RS-68s yielded no fruit. Methane would have been a far better choice for, say, the Delta IV booster cores than hydrogen. Hydrogen gives away so much of its vacuum Isp at sea level that methane is pretty much a match for it and would have allowed smaller and lighter tankage and better performance – and none of that self-scorching rocket stuff either. Perhaps the emblematic orange spray-on insulation could have been deleted too. That would have saved even more weight.
Elon is not “afraid” of hydrogen, he just understands that using it brings a lot of headaches and modest benefits given the use cases he has in mind for Starship.
Stoke embraces hydrogen because it is key to Nova’s whole second stage reusability approach. But even Stoke doesn’t launch on the stuff.
[This post about Rocketdyne is off-topic since it is just fond memories of a time past …]
1. Lived a few blocks from Rocketdyne’s Canoga Park HQ & manufacturing plant, when I was a kid.
2. Used to hear the rocket engines being tested over the Chatsworth hills in the Simi Valley area quite frequently.
3. 9th grade math teacher was a former Rocketdyne engineer, laid off in the big Southern California aerospace crash of the late ’60s. One day he got tired of teaching us 9th graders math and instead spent the hour teaching us the rudiments of FORTRAN. That was all it took for me: I knew I wanted to be a computer programmer. Taught myself from books in the public library, and goofed around in the “computer lab” at the local 2yr college (they had an already obsolete IBM 1620). Went to Harvey Mudd College and spent the next 50 years (50 years this year!) programming computers as a career. (Of course quite some time ago the “profession” decided to upgrade itself and now we’re no longer “computer programmers”, now we all call ourselves “software ENGINEERS“. As if! I.e., as if we as a group routinely produce software to the same standards of reliability and longevity as your civil engineers, mechanical engineers, etc. etc. Oh, don’t get me started …)
The quick link post is an open thread. You are free to discuss anything space related. No need to apologize.
I love hearing tales about tribal knowledge…work environments…
Space lasers…for reals…just on the small side
https://phys.org/news/2026-08-miniaturized-laser-technology-paves-fundamental.html
Thank you for that link, which had the interesting words “Einstein Elevator” in it, which brought me to this, which is fascinating of itself.
(And, BTW, the “tower-in-tower” idea so that only the experiment capsule rather than the entire free-fall pathway needs to be evacuated to (near) vacuum seems obvious, so why wasn’t one built sooner?)