RCgothic

Whilst you wouldn't want to stay in the Van Allen belts, this isn't anything humans haven't done before. It'd take just under two months of exposure to the worst bits to accumulate a fatal dose with shielding of 3mm aluminium (25sv/year). Dragons are considerably better shielded than this, the trajectory will avoid the worst areas, and they aren't going to be staying there for months. A few orbits only. Apollo and Gemini both transited the belts with no ill effects to astronauts. Apollo doses were dominated by solar particles outside earth's magnetic field. I think it's awesome people are going beyond LEO for the first time since Apollo.

An RFA rocket just exploded at the UK's Shetland launch site: https://www.bbc.co.uk/news/articles/cy54wqzz0kvo.amp

Hardly anyone else even has a reusable S1. Only electron, to nowhere near the extent of F9 thus far. Reusable vs reusable battle is a long way off IMO. It's cool that Stoke, RL and BO are working on potentially competing approaches. Maybe Stoke's approach might be more easily realisable than starship. But for certain payloads (e.g. propellant) if each approach is fully realised that won't be anywhere close to as rapidly relaunchable as a "land on the launch tower". Additionally, having an enormous mass margin will certainly not hurt. If Starship achieves full and rapid reusability, but it only manages 25t payload to orbit and something like 300 tonnes are required for rapid reuse, that still undercuts Falcon, current market leader in cost efficiency per payload, by a factor of at least 5. If Stoke needs 50t dry mass to LEO for rapid reusability but total mass to orbit ends up being 40t, they'll be stuck. Also the "but it'll be oversized!" case is somewhat rebutted by pointing at the transporter missions that are currently eating smallsat launchers' lunch. If there's a payload capacity of 200t and a customer only needs to send up 2t, it'll be sent up with 50-100 other payloads and the "Cesna" won't compete against the "A320" outside of extremely niche applications.

Probably "Wow, wasn't expecting Sierra Space to be the buyer"

I suspect a folded telescope won't challenge the LEO payload of Starship in reusable mode. And if we want bigger than what will comfortably fold up, we're into multiple missions anyway.

Three times the expendable payload of Saturn V certainly makes an impressive benchmark, but it doesn't make for an impressive moon mission. Replacing SLS with Superheavy fixes a cost issue at least, but it doesn't advance long-term goals. The only use cases I'd find interesting for a single-stick expendable launch are truly enormous monolithic payloads to LEO. But even space stations and telescopes don't need that, just send them up in segments. Currently the only thing I can think of might be a very large nuclear powered tug where the reactor can't be subdivided.

I still don't understand why anyone would just want a repeat of Apollo. It'd land twice and get cancelled. The way EUS is going it might not even manage that. The goal is permanently inhabited lunar bases and crewed beyond earth-moon explorations. Tanker flights get us that. With that within our grasp I don't care at all about pathetically undersized single stick missions.

If US or western european crews don't go up on Starliner before they go up again on Soyuz I'd be shocked.

Also it isn't just a case of "get bombarded by radiation, get activated". Some materials are susceptible to activation by particular forms of radiation, such as cobalt to neutron bombardment by, and if there's a perceived risk of activation by particular forms of radiation then materials containing susceptible elements can be avoided.

Also, 3430m/s for a 250km orbit is only accurate to 3sf. (3427.34m/s).

I've double-checked the table maths and the referenced Sopegno Et Al article. Table 4 does indeed use only a 250km orbit, but Sopegno uses 500km. The correct DV of target altitude should be 3315m/s not 3430m/s in Lines 3 and 4. So the DV losses for lines 3 and 4 should be 1069m/s and 1060m/s respectively, not 954m/s and 945m/s. The commenter is accurate. Maybe do a minimum of legwork yourself before casting aspersions next time. Also, intuitively, all other things being equal on a nearly airless body, the higher the TWR the less the gravity losses. Line 2 having higher losses than Line 1 despite higher TWR warrants further explanation IMO.

The "longest lived" wastes are the transuranics that can either be bred into more fissile material and used as fuel or already are fissile and just need reprocessing. They're also the least dangerous constituent of used fuel and not worth going out of our way to annihilate. Given that there has never been an incident of anyone being harmed by dry-stored fuel and that nothing has ever been stolen from a dry store (casks weigh over a hundred tonnes and require specialist equipment to move or open), the salt mine is unnecessary. I think the only thing would be if a nuclear site goes inactive casks should be transferred to another nuclear site with active security arrangements, but that'd still be easier than a salt mine. I agree casks shouldn't just be left unmonitored.

As a nuclear fuel handling engineer, I curse anytime anyone mentions geological disposal facilities. We are absolutely going to want access to this high-grade resource as soon as it's economically feasible to reprocess it, it should be criminal to waste it by burying.

And yet the only company that regularly reuses anything has a profit margin so large it can simultaneously deploy a mega constellation, develop a rocket three times as powerful as Saturn V, and crush the only other bidder for the ISS de-orbit vehicle so absolutely that it sparked an article that gist of which is: "Wow. How can anyone else compete?"

I wonder how much DV that dragon has as an independent vehicle

We don't need an abandoned space station slowly shedding debris into an orbit with decay times measured in centuries to millennia. NASA's got this call right IMO.

Using sat thrusters to recover a useful orbit is pretty much exactly how JMcD defines "useable".

I guess that's why JMcD scores non-nominal but usable orbits 0.75 of a success, and orbital but unusable 0.4.

Oh dear Arianespace. Not another one. Wikipedia is saying failure of Vinci's APU, and it was an intended de-orbit burn (with apoapsis raise as well for steeper descent?) That doesn't sound too critical, should sort it in the next flight.

Booster explodes in landing conditions it's not designed for shocker.

By my count Raptor is coming up on half as many launch and in flight ignitions as Rocketlab's Rutherford by the way. I think Raptor is on 224 counting all of those that started and burned for more than a second from Starhopper through IFT4. Rutherford is on about 490 I think?

I don't know who originally started the "Boeing Astronauts Stranded" line, but it's never actually been the case and it seems like a lot of outlets are just copying the lede and running with it.

Europe clearly needs to do something to compete. But even if they put forward a design targeting falcon-like cadence and reusability, by the time it's ready it'd already be obsolete. Needs a much larger rethink than just producing an all-liquid ariane variant. They need an engine that can be produced at a rate of several per day, with better-than-Merlin levels of reusability, and enough thrust to not need solid boosters for assistance. Hydrogen engines are out on poor thrust and difficulty to refurb (tricky h2 seals). Kerolox is out because of coking. So they probably need a methalox engine as a starting point

Because it can't be fixed or adequately preserved and will inevitably disintegrate, posing a hazard to all spaceflight in it's orbit and nearby orbits. Far better to end it decisively.