RCgothic

Gravity is a field. Setting up a gravity field would take energy at least equivalent to moving every massive object within it from infinity to its position inside the field, because work is energy is force times distance. How much energy this is depends on the size of the field. If the field drops from 1g to ~0 over 10m it could be as little as 12.5J/kg for objects at the 1g level. Less for objects further away, more for any objects below the "deck". For this reason the design would probably need to minimise the mass between the artificial gravity generator and the useful gravity zone. The energy put into establishing the field may be regeneratively recovered when it's disestablished. For comparison 1J isn't a lot. It takes 4200J to heat 1kg of water by 1°C. It needn't take any energy to maintain a gravity field either. Objects at rest within a field aren't having any work done upon them. The system would need to supply the energy for any movement of objects. The only question then is how efficiently your gravity generator can convert electrical power into gravity fields and keep them operating. And as this is mythic tech with no known, this could be anything from next to nothing to "needs energy totalling the mass of a planetoid with equivalent surface gravity".

Yeah, if I'd had to bet on which one of Virgin Orbit or Galactic would survive, I'd have picked Orbit. Now I'm thinking neither.

So Vulcan probably isn't launching H1:

Historically yes, total cost per launch has been king. And it is still possible to win some launches that way (for now). But that's not where launch growth is and danger that way lurks. If Rocket A can launch 20 sats at once for $45m, Rocket B can launch 9 sats at once for $30m, and you have 360 sats to launch, all else being equal you pick Rocket A because you'd only pay $810m for 18 launches instead of $1.2B. And also Rocket A just won 18 launches together instead of negotiating them individually. Megaconstellations are where the growth is. If Neutron can't get into that market, then it will have failed. If Rocket B does some work and gets it's cost down to $20m, then congrats - the cost per kg (or per sat) is now competitive. Otherwise the fact it's cheaper per launch will only win it a fraction of the launches Rocket A gets in future. Now imagine Rocket A can launch for $38m for the same profit margin Rocket B makes at $34m, and Rocket B really can't easily go below $30m and still repay it's creditors. Except Company A is more financially secure than Company B and not beholden to shareholders. It can happily operate at $28m per launch for a while while it puts Company B out of business. This is the situation Rocketlab are in danger of finding themselves in - unable to compete on price per kg or per total launch. Finally, Rocket A2 is on the horizon. Rocket A2 recovers all hardware, only needs maintenance every few flights, is reusable over dozens of flights, and its only major BOM cost is fuel. It can launch 100 sats at once and gets charged out to customers at $25m per flight which is a profit margin of about 1000%. Rocket A2 is the Dreadnaught of rockets, and it makes all other rockets obsolete. Companies B, C, D and so on through Z are all screwed if they're pinning their hopes on their newest offerings *maybe* being competitive with the original Rocket A.

All else being equal, if the enormous aircraft is cheaper why not? You're loading the question by using an example where obviously the A380 is more expensive for sole use than a regional jet. But that's really not an equivalent situation. The Falcon family has the best safety record. The highest availability. More margin than it's competitors. Enough orbital insertion accuracy for all purposes. And a much lower price per kg. There are a few prizes for second place. The DoD's mandatory 2nd supplier, or competitors looking for an "anyone but SpaceX" option. But the rewards are nowhere near as much as for being a genuine contender. Absent any of those reasons, the only way to secure a launch contact is to be cheaper per individual launch for sats that can't multi-manifest. But not only is Falcon 9 looking like a similar marginal material cost to Neutron expendably, SpaceX are more financially secure and well placed placed to undercut by applying a lower price margin. And again - F9 has a lot more capability. Is Neutron really going to undercut F9 flying expendably on missions F9 can RTLS or ASDS for? I'm guessing not. Ironically, Electron can. On total cost at least, if not per kg. But the smallsat individual launch market doesn't have a future with the rise of ride-sharing, which is why RL are going for a bigger launcher with Neutron. And on top of all that, Starship is coming. Like @tater says, a SpaceX competitor needs to be *grossly* under-selling SpaceX to capture their market. Because they won't be overtaking F9 on safety record or availability for quite some time. And yeah, that's really hard. Not every SpaceX competitor is going to make it.

Astra's Chris Kemp asserts RL won't be competitive with SpaceX at 8t for $50m-$55m. RL's Peter Beck corrects that actually is 13t disposable. So the article states materials for Neutron at $20m-$25m. At 50% margin that'd sell for maybe as little as $30m for 13t, or $2.3k/kg. SpaceX can do 23t for $15m-$30m internally, so maybe selling for as much as $45m with a 50% margin. That's $2.0k/kg. At the opposite extreme, F9 may be able to manage $1k/kg with a 50% margin whilst Neutron could be at $2.9k/kg. So it looks like Neutron will probably be between 115% (best case) to 290% (worst case) as expensive as F9 for 3rd party megaconstellations, which will be the main external customers for launches going forward. Chris Kemp is entirely correct that RL needs to do better.

Also, "unused capacity" is irrelevant, all other things being equal. It may actually be preferable, because a rocket flying comfortably under its capacity will be able to accomplish its mission after an engine-out, and/or fly a less efficient but more payload friendly trajectory. A rocket flying right at its limit has no contingency.

Falcon 9's internal marginal cost at last given numbers was somewhere between $15m for RTLS or expended at end of life and $30m for an all new vehicle expanded on first flight. F9's disposable upper stage is bigger than Neutron's, and F9 doesn't have perfect reuse on fairings. It's certainly feasible that Neutron has a path to being cheaper than F9. That's why it's disappointing that it's not. There's a crowd of competitors all coming out with their own next gen vehicles, and only Relativity seems to be aiming beyond F9. ULA Vulcan will probably do ok due to DoD and "anyone but SpaceX" Kuiper contracts, but in the long run even they will need to go back to the drawing board. If Neutron had been able to undercut F9 with a similar cost per kg (which is the metric for megaconstellations that Peter Beck explicitly wants in on), then Neutron could have been a genuine contender. If this sounds like I'm being negative about RL then I'm sorry - I genuinely want someone to get into a serious price war with SpaceX but it doesn't sound like Neutron's going to be well positioned for that anymore.

Same price, half as capable, over half a decade later to market. It's honestly a little disappointing.

Fission can just be turned on and off. ~6% operating thermal power comes from fission product decay though, reducing to about 0.1% over ~40 days, so. You don't necessarily have to provide cooling for decay heat if you don't care about the state of the engine after it's finished firing (propellant exhausted, non-earth intersecting stage trajectory, doesn't matter if it melts.) Fission fragment engines avoid this altogether by exhausting the fuel, so the engine isn't going to get hot from spent fuel emitting decay heat inside the engine But there's no reason not to tap some heat off the power cycle (or decay heat cooling) for electricity generation if you don't mind bringing a little extra mass along.

Everybody falls the first time.

V2 minis (F9 compatible), not V2 (Starship only) Not heard anything new on that beyond the tweet I think you're referring to.

Tory Bruno gets a big pass for being a thoroughly nice guy. But it's a very pro-what-ULA-developed slant on the whole process for obvious reasons. I agree entirely with this Twitter thread rebuttal:

Duna Mission, had a Mk1-3 gumball with a large lander in an XL large cargo bay. Arrived at Duna, and and launched the lander by opening the cargo bay and decoupling by a large decoupler. The camera and navball stayed fixed to the original craft, but the control inputs were affecting the lander. (Impossible to pilot lander). Kerbal manager/resource manager/tracking station still treated the ship as one unit despite it being in different physics bits and drifting in multiple directions. Unable to swap between control of craft.

Eye roll at the potential date.

"no crasher stages" is a particular issue for disposal of earth departure stages. Those come in especially hot & heavy.

This "reveal" seems like a load of nothing to me, given that they're using a cover layer on the space suit to conceal the actual details.

I still don't understand why "don't build a noodle" is something you have to teach. There's no good reason for long rockets not to be a valid design. You shouldn't have to strut side boosters up like a Christmas tree just so the wibbling thrust vectors don't cause the rocket to flip despite appropriate CoM/CoA positions. These are all artificial workarounds that fail to address the root flaw: unstable rockets are frustrating, creatively limiting, and unfun.

This couldn't be stupider if they tried: STS is already the system name for the space shuttle, so this is just going to cause confusion. The whole Artemis/Orion/SLS naming has been a bin fire from the start.

"Don't build rockets that look like F9" is a bug, not a feature.

NASA has dropped an updated timeline:

Block 1B delayed to 2028.

People keep saying bendy rockets are a "feature" that younger players appreciate, and I just can't get my head around how *anyone* would prefer a feature that effectively disables the stability assist and adds this much frustration to controlling larger rockets. Who likes building large rockets? Everyone. Who likes trying to fly a wet noodle that will crash no matter the skill of the pilot? Is there even one person?