asssuber t1_je5u5qc wrote

Look at the proposals for protecting Earth during it's next geomagnetic reversal. I can't find now, but there are basically two main approaches: the L1 satellite one that DanFlashesSales said, and the superconducting rings over the surface that more closely reproduce the natural magnetosphere. For Mars, as far as it don't have a huge industry, the first one seems more realistic, but both are massive enterprises.


asssuber t1_jag4xjh wrote

At a much higher cost, regardless of the advances in reusable rockets. Not to mention much harder to do maintence/upgrades/change instruments.

Arecibo Observatory didn't even receive enough funding to prevent it from colapsing. You can't replace the entirety of ground astronomy with space telescopes even if it got an order magnitude more funding, that also won't happen.


asssuber t1_j9wgqvt wrote

> They lit 31 engines, a world record.

They lit 32 engines, one shut down during the (short) static fire.

> The last time someone tried 30 they blew up four rockets in a row, the second one destroying the launch facility.

N1 is a very low standard to compare against. It's engines could not even be test fired prior to being mounted in the rocket, much less had a chance to do a full static fire like SH. Those were also the first staged combustion engines ever made, oxygen-rich on top. And the failures had more to do with the rocket than the engines themselves.

On the other end a very high standard of reliability is given by SpaceX itself. SpaceX flew Falcon Heavy five times, each firing 27 engines (plus the upper stage one) and it was 100% successful with no Merlin having a problem in any of the flights. 27 is almost the same as 30, the phantasm of N1 was slayed by SpaceX itself already.

Raptor is clearly immature and problematic if you compare it with Merlin, RD-180, Vulcan-2, etc. We have seen it's engine-rich exhaust several times and they are still tweaking the film-cooling for optimal performance, and might have other problems they haven't spoken.

Given ULA's more stringent standards (they aren't expecting to lose/scrap several test vehicles, going through dozens of engines like Spacex. They don't have engine-out capability to shrug off a few bad engines like SH), I do not see BE-4 as being less fine than Raptor.


asssuber t1_j9v5wdd wrote

Raptor isn't doing that fine. You had many failing during starship's fights (not always the engine fault, but still) and 2 failing in the latest static fire. IIRC it also started development before the BE-4 (well before if you count when it was still supposed to burn hydrogen, but not much development was happening then). And let's not talk about deadlines, we all know that in the space industry they are just optimistic targets.

The RD-180 is a Russian engine, they have experience with oxygen-rich stage combustion, not the USA. AFAIK BE-4 will be the first oxygen-rich staged combustion engine made in USA to be flown (if we ignore that a full flow staged combustion engine also has an oxygen-rich side).