robbak

joined 1 year ago
[–] robbak@sh.itjust.works 2 points 10 months ago (2 children)

No. It is part of the space treaty that most nations have signed up to, that any part of a space craft remains the property of whoever launched it, and clean-up of it is the responsibility of the country from which it is launched.

[–] robbak@sh.itjust.works 7 points 11 months ago

Once burnt, yes, safe greenhouse gas. At least, no worse than any other combustion products. I mean, it would be nice if hydrogen wasn't such a pain, but we have to work with the universe we are given.

Methane leaks need to be contained to the amount practical, but they are doing that.

[–] robbak@sh.itjust.works 2 points 1 year ago

SpaceX has completed their mishap report, which states what they believe are the required corrective actions, actions which, it can likely be assumed, they have already completed. So all that is needed, from their standpoint, is for the FAA to accept their report, accept their corrective actions, accept the actions as done, and issue the launch license.

FAA could, however, decide against any of those things - that the report hasn't covered something, that other actions are required, that the actions haven't been properly done.

This is entirely in line with everything that both FAA and SpaceX have said.

[–] robbak@sh.itjust.works 2 points 1 year ago

I, too, love the idea of a wet workshop, but I see the problems. Mostly, tanks don't need micrometeriod shielding and insulation, and weight-efficient shielding and insulation would not survive launch. The kind of protection you'd need to add would easily double the mass of the empty tank, or you'd have to somehow wrap the tank in space. The reward is enormous amounts of habitable volume, but I can't see the cost.

[–] robbak@sh.itjust.works 5 points 1 year ago

Revenue is money coming in. It never includes operating expenses. So the 'excludes expenses...' statement is just so people without business knowledge won't think this is 8 billion in profit.

[–] robbak@sh.itjust.works 4 points 1 year ago

Another thing we injoyed was much better second stage footage. They splashed out for some really good, but disposable, cameras.

[–] robbak@sh.itjust.works 1 points 1 year ago

The regular raptor bells (and the regular Merlin bells, which we are discussing here) are made from a copper-rich alloy, for high thermal conductivity. They are fully regeneratively cooled by the engine's fuel (kero or methane). The extensions are radiatively cooled, with the base section film cooled by bleeding the cooler turbopump exhaust in a ring around the base of the extension/lip or the nozzle.

[–] robbak@sh.itjust.works 1 points 1 year ago

I don't suggest that the lack of glow tells us that it is made from different stuff - as you say, that section of the bell doesn't normally glow - but that the fact it doesn't glow means that it isn't that hot, doesn't need to deal with high temperatures, and therefore doesn't need to be made from any expensive alloy.

 

WE know the original full-size bell is made from a very expensive niobium alloy, for heat resistance. But I notice that the new bell hardly glows at all - just very faintly at the extreme outer edge. The film cooling provided by the turbopump exhaust protects it completely.

So, I am wondering - are they still using that expensive niobium for the stubby nozzle? From what I can see of the bell, they could use simple mild steel and be perfectly OK.

[–] robbak@sh.itjust.works 3 points 1 year ago

They can't dig a trench. The water table is often above the natural ground level, and their pads are only a few feet above that. When starship dug that hole, water seeped in and partially filled it!

But it is the same thing at the cape - but there they brought in soil and built up the land by something like 10 meters, and built their pads and trenches in that. Moving in that much dirt would take years.