The Great Ongoing Space Exploration Thread

Miscellaneous and Personal Stuff I Must Share
1382

Returning briefly to SpinLaunch …

Have we learned nothing from the years of Punkin’ Chunkin’ on Discovery Channel?

The centrifugal category is notable for two things: 1) The launcher destroying itself during wind-up; and 2) The launch angle and hence trajectory of the punkin being wildly unpredictable.

I honestly think that category remains in their competition solely for the very entertaining ways the machines fail. So-oo videogenic.


Obviously I’m being lighthearted here, but IMO SpinLaunch be wack; there’s just no way those engineering tradeoffs actually make sense except to some mad scientist with a fixation on all things centripetal / centrifugal.

Of course no mention of “mad scientist” and “centripetal / centrifugal” in the same sentence can go without a cite to this vintage work of high art:

1383

Not so great:

Well, at least it’s not Boeing shitting the bed. Just another oldspace contractor.

Collins is again supposed to be the old reliable one. But one of the commenters points this out:

As a note, Collins’ spacesuit experience is through multiple acquisitions. The original designer was Hamilton Standard. In 1999, Hamilton Standard merged with Sundstrand to become Hamilton Sundstrand. In 2012, Hamilton Sundstrand was merged with Goodrich to form UTC Aerospace Systems. In 2018, United Technologies acquired Rockwell Collins and merged it with UTC Aerospace Systems to form Collins Aerospace, and in 2020 United Technologies and Raytheon merged to form Raytheon Technologies.

Not a good recipe for maintaining institutional knowledge, which is really the only reason to prefer these older contractors. Good chance there are none of the original managers or engineers left, and in any case having to go through several corporate culture shifts is enough to destroy whatever knowledge might have remained.

So what next? SpaceX has an EVA suit now, but it isn’t self-contained (no backpack), is missing some useful elements (like waist articulation), and certainly can’t go to the moon in the current state. But maybe it’s possible to evolve the current design into something that can. Whether they make a bid is a different question. Not sure who else might be in play, except for foreign designs.

1384

SpaceX is going to destroy the space station:

Hope it doesn’t land on someone’s house.

No details yet, but I’m guessing this is a Dragon with extra propellant. $843M doesn’t buy you a whole new vehicle, but it’s a good price for a retrofitted Dragon.

1385

Wow. Talk about SpaceX destroying OldSpace. It’s been a figure of speech for a decade-ish and now it’s to become a reality.

That’s the kind of symbolism you’d pooh-pooh as contrived if you came across it in a novel.

1386

I have to admit, the metaphor didn’t quite occur to me when I posted that. But SpaceX giving oldspace a shove into fiery doom is quite the bit of imagery.

I hope we get a livestream via Starlink!

1387

NASA clearly missing a trick with this deorbit contract. If they just gave it to Boeing, the ISS would stay in orbit forever!

1388

Either that or the beta test would result in it landing intact on NYC or Washington DC. Oops. Then they’d ask for a supplemental to get it right the second time.

1389

If only Zapp Brannigan were around:

CNBC had a bit more detail on things:

In particular, they link to an interesting NASA study:

The study looks at the alternative of increasing the ISS orbit so it can stick around for longer:
Imgur

But they think it’s too much risk as it would depend on Starship or equivalent. I think that suggests it’ll be a modified Dragon. 9000 kg of propellant should be doable.

1390

The punchline seemingly being that ISS is rather fragile. So it needs to be gently nudged in whatever direction. Implying a large delta-V would take a long time to apply. A box-stock Starship is simply too big a sledgehammer.

Assuming Starship gets operational, they could certainly put a docking adaptor on one end and a Dragon-sized engine on the other and drive ISS to the Moon if they wanted. It’d just take a very long time to get going fast enough to get there.

More sensibly you’d build a gizmo that is a docking adaptor on one end, a Dragon engine on the other, and have that carried as payload by a Starship. Once in place at ISS, treat the Starship as simply a giant external tank Shuttle style with plumbing leading to the docking/engine module alongside that does the actual pushing on the entire ISS/Starship stack.

For damned sure it’s cheaper to take an almost stock Dragon and de-orbit.

1391

Dang, dude. :slight_smile:

1392

As the kids say: “Wicked burn”. But not the de-orbit kind. :wink:

1393

Eric Berger thinks it’ll be a Dragon XL:

SpaceX is already developing the XL, which is an expendable, cargo-only version of Dragon meant for the lunar gateway. So it’s not totally implausible.

I still lean toward the plain Dragon, though. There’s enough room in the trunk for the propellant.

Dragon has the SuperDraco thrusters, whereas I expect the XL does not. These are typically only used for launch escape–but the ISS will need a significant push! It weighs around 400,000 kg and needs 60 m/s of delta-V to deorbit. I don’t know what timescale they’re looking at–but if they want a reentry into a specific location, I think it needs to be a relatively small part of an orbit. Let’s say a 10 minute burn (an orbit is 90 minutes). That’s 0.1 m/s^2 (1% of a gee), and 40 kN of force.

A SuperDraco has 71 kN of thrust but can throttle down to 20%. And I’m assuming they’ll want to fire two for symmetry. Two of them throttled to 28% gives the required 40 kN force. The standard Draco maneuvering thrusters are only 400 N each–you’d need 100 of them! Even if I’m pretty far off on the timescale, it’s still not enough.

One sorta funny bit from the article:

The bidding process for the US Deorbit Vehicle was opaque, but there are a few intriguing clues. Initially, the contract was offered as a hybrid. NASA’s original documents said the “design” portion of the contract would be cost-plus and the development portion firm-fixed-price. Then a couple of things happened. Perhaps because there were not that many bidders (one source suggested to Ars that SpaceX did not even bid initially), NASA modified the process to allow flexibility on the contracting mechanism.
…
And notably, the award is entirely based on a firm-fixed-price contract, which is SpaceX’s preferred way of working with NASA.

So Boeing refuses to bid anything as firm-fixed-price, whereas SpaceX refuses to bid anything except firm-fixed-price.

Boeing of course loves cost-plus. It requires an army of accountants to verify that every nut and bolt is accounted for and they aren’t overcharging the government by a penny. And a smaller army of accountants to keep track of the first army. Of course, all of this gets charged to the government.

SpaceX seems unwilling to increase the number of beancounters to support bidding on cost-plus.

1394

Robert Heinlein did something of the sort in The Moon is a Harsh Mistress (although not to Maastricht in the Netherlands, worse luck).

1395

Massaging the rules of a RFP before the fact to control (or yugely influence) who wins is a time-honored tradition of both government and corporate vendor selection.

1396

Don’t forget to attach your rocket securely to the test stand, folks!

Do watch the video in the story, it’s quite something. China claims no injuries, which seems miraculous.

1397

Wow.

That test facility is not far outside that dense city. China is densely populated, so it’s hard to find wide open spaces that are also convenient to the people who’d work building this stuff. But geez!

1398

On the Chinese booster that broke loose and took off during a hot fire test, the company has issued a statement

The team decided to go to full thrust because the test was going well, not realizing the vehicle hold-downs were only rated for the test thrust.

The team believed the full launch-rated hold-downs were in place, but they weren’t. So the rocket effectively launched, without a second stage, payload, or avionics.

1399

Cue Sergio Aragonés cartoon: a mechanic in an airplane hanger is staring in puzzlement at a hex nut he can’t account for; in the distance, a jet airliner is having a wing break off.

1400

If that was truly an ad lib spur-of-the-moment decision, that speaks very poorly of their discipline.

If, OTOH, the test card was changed some time weeks ago to included a possible bump to full thrust given favorable prelimiinary results A, B, & C during the run, but test systems engineering never noticed the disconnect between the card change and the rest of the test pad’s hardware config, that suggests process problems.

Either way, a high consequence oops outcome for a small decision. Space is like that.

1401

That blowed up real good! :+1: :cn: :grin: