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the cost of launching a scope is not the bottleneck.

• pfdietz 4y ago
  High cost of launch prevents economical repair (especially in high orbits), which requires extreme reliability. It also creates incentive for extreme weight reduction. Both these drive up the cost of a satellite. At low launch cost, there's no reason a space telescope should be much more expensive than a terrestrial telescope of the same size.
  • dekhn 4y ago
    Do you work in the field of space? I don't mean to be dismissive but claiming that space telescopes cost about the same as terrestrial scopes if you subtract out the launch costs and can maintain them with crews, isn't really consistent with what I've heard from space telescope astronomers.
  • spenczar5 4y ago
    No, that goes way too far. Radiation hardening and heat dissipation are really difficult problems that remain for any space telescopes. (I'm at the University of Washington Department of Astronomy, and work on telescope software).
    • pfdietz 4y ago
      With sufficiently cheap launch, you get radiation hardening with shielding. The goal is to use off the shelf hardware as much as you can. If things break, that's why we have servicing, just like on terrestrial telescopes.
      • AnimalMuppet 4y ago
        The cost of rolling a truck to a terrestrial telescope is several orders of magnitude smaller than the cost of servicing a telescope in space. From that difference flows a greater emphasis on reliability for a space-based scope.
      • dekhn 4y ago
        Ah. So, I should have said this earlier: there's a whole different world of cubesats that are what you're looking for. We could almost certainly help the astro community by funding and launching large fleets of simple scopes that make observing time available to more researchers. You don't service cubesats, you just learn from your past mistakes and launch more.
• sebzim4500 4y ago
  No, but the mass and volume constraints are. See how much effort went into making JWST fold up and how hard they had to try to get the mirrors to be light enough.
  • pfdietz 4y ago
    That's where in-space assembly comes in. It's kind of sad that the one real thing the Space Station demonstrated, assembly of large space structures, has been abandoned in the name of feeding the pork pipeline with SLS.
    • nordsieck 4y ago
      Why do you say it's been abandoned? SLS will be delivering segments of Gateway after the first 2 are delivered by Falcon Heavy.
      • pfdietz 4y ago
        ISS involved assembling segments that could be lifted on the Shuttle. Continuing that would involve lifting segments that could be lifted on F9 or FH. There would be no need for something as large as SLS.
      • sbierwagen 4y ago
        SLS is expending surplus RS-25 shuttle engines. Once they're gone they'll be paying Aerojet Rocketdyne a hundred million each for new ones. The first stage uses four. Eventually someone with a brain is going to notice, SLS will be canceled, and decades of federal jail time will ensue for the criminals who perpetuated this fraud upon the American people.
    • tsimionescu 4y ago
      Given that SLS works and Starship has failed pretty spectacularly so far (engines failing off the gate and in flight, launch site damage, failed to detonate on demand), I think it's about time to stop saying SLS is just pork.
• nordsieck 4y ago
  > the cost of launching a scope is not the bottleneck. Starship isn't just about price, but also fairing volume. And fairing volume is one of the major factors that drives telescope design. It's even possible that SpaceX would do a limited run hammerhead fairing for the right price.
  • cubefox 4y ago
    Not sure a larger fairing would be compatible with the current tower. Though they could use landing legs, then it doesn't have to be caught mid flight.
    • nordsieck 4y ago
      > Not sure a larger fairing would be compatible with the current tower. I'd imagine that a hammerhead fairing would mean an expended 2nd stage. There's just too much custom work that would have to be done (for example with the heat shield) to really make it work. But if the cost is reasonable (I'm guessing ~$25 million for an upper stage), that isn't a bad price to pay to get access to a 12m fairing.
      • cubefox 4y ago
        I think 25 million USD is too optimistic, since the Starship upper stage has six raptor engines, and the Falcon 9 upper stage has only one Merlin engine, but a launch price of around 60 million US dollars. But NASA would pay much more than that if it means they can launch a telescope with a big mirror that doesn't need to be folded in. The main problem I see is that they would likely also have to pay for the entire development of the new upper stage, which would be much higher than the pure launch cost. Since NASA already has JWST, I'm not sure they have much interest in a big new space telescope currently. Other than that, it's not clear what a super large payload fairing would be required for.
        • nordsieck 4y ago
          > The main problem I see is that they would likely also have to pay for the entire development of the new upper stage I don't see why they'd need to do a full 2nd stage. I'm sure a limited run fairing (especially a complicated one like a hammerhead) will be expensive - certainly quite a bit more than the $5 million per unit cost of the Falcon fairings. But ultimately a fairing just isn't that complicated, and SpaceX has a lot of experience with them.