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Orbital telescopes are much better suited for this.

rtkwe 7y ago
They're also much much more expensive and less flexible. With earth based satellites new experiments with new instrumentation is easy, in space currently we have no way to fix any issues.
- thecount122195 7y ago
  We can and have fixed space telescopes before, probably the most famous example is Hubble and its poor sight. https://en.wikipedia.org/wiki/Hubble_Space_Telescope#Flawed_mirror https://en.wikipedia.org/wiki/Hubble_Space_Telescope#Flawed_...
  - rtkwe 7y ago
    We did but not any more 1) there's no longer anything like the shuttle available the only thing that could get close would take two launches to stage the parts and another for the crew capsule (not to mention most US capsules would have to evacuate the entire capsule to go outside iirc) and 2) most of the current space based telescopes like James Webb will be much much further out than Hubble was and most that get announced are also planned to orbit much further from Earth.
  - kuschku 7y ago
    So which space shuttle should we use to fix James Webb if anything would go wrong after the launch? Currently no country has a well-working solution for that, nor does any company (not even SpaceX themselves)
    - sp332 7y ago
      JWST is for researching high-redshift object - the most distant things we can see in the universe. It's not a planet-hunter. And it will be much further away than other satellites, so they would be more easily serviced. (Not that it's easy, I just think you picked a bad example.)
      - privong 7y ago
        > JWST is for researching high-redshift object - the most distant things we can see in the universe. It's not a planet-hunter. JWST is a general purpose observatory. It will make significant advances for high-redshift objects. It will not survey large numbers of star for new planets, but it will be able to observe and characterize planets that have been identified by other missions/observatories.
    - mdorazio 7y ago
      Your comment assumes we still need fleshy meatbags wearing clunky suits in orbit to fix things. This was true 15 years ago, but I'm not convinced it's still true today. A couple of repair drones housed at the ISS combined with repair parts brought up along with normal resupply missions could probably be made to work if it was deemed cost effective.
      - plotteddancer16 7y ago
        This is a misconception. The ISS is not in an orbit that’s suitable for repairing satellites in other orbits.
      - rtkwe 7y ago
        The ISS isn't in a particularly good orbit because it's highly inclined (so Russia could easily launch to it) which is an expensive issue to fix dV wise unless all the target satellites are in a similarly inclined orbit. In terms of making them easy to swap out that's certainly possible but it will add weight compared to a monolithic satellite and so far we have very very little experience building and repairing things in space without using people.
      - dragonwriter 7y ago
        > could probably be made to work IOW, is a speculative, unproven idea.
    - Robotbeat 7y ago
      SpaceX is working on Starship, which should be capable of Shuttle-like service missions. (JWST is much more fragile than Hubble, however, so you'd need to build a custom servicing solution... but JWST is not representative of space telescopes generally.) In fact, SpaceX is counting on Starship to deploy their full constellation. No Starship, no 12,000 satellites.
      - rtkwe 7y ago
        I think JWST is going to look a lot like the future of space telescopes. There's hard requirements that make larger satellites better for observation, principally because larger aperture == better resolution and also because the larger mirror gathers more light so we can look at dimmer objects.
        Robotbeat 7y ago
        It's not the size of JWST, it's the fact that it's deeply cryogenic and uses enormous, fragile multilayer insulation to remain so. Indeed, larger apertures will be used increasingly. And this megaconstellation actually enables that indirectly. SpaceX is counting on their Starship launch vehicle to deploy the vast majority of their 12,000 satellite constellation, and indeed large launch vehicles (particularly reusable ones) require a lot of payloads to justify their development cost. But large launch vehicles also enable ever-larger telescopes, whose cost is only affordable if those launch vehicles are reusable. NASA is already buying into it. Here's NASA Goddard tweeting out the larger-than-JWST concept called LUVOIR inside SpaceX's Starship (which again relies on the megaconstellation for demand): https://twitter.com/nasagoddard/status/1116310431969239040?lang=en https://twitter.com/nasagoddard/status/1116310431969239040?l... ...and yet larger apertures will require in-space assembly over several launches, again only really affordable if there's enough commercial launch demand (i.e. from megaconstellations in particular) to justify these large reusable launch vehicles. My point of view is that if we're going to be a really spacefaring civilization, it's reasonable that you'll be able to see human artifacts in the sky. Starlink is actually fairly easily stealthed, but other things (space based solar power stations, large space stations, in-space manufacturing depots, etc) may not be so easily hidden. Is the fact that human artifacts may be detectable in the night sky reason enough to disallow spacefaring? EDIT: Note that the IAU letter is way more reasonable than almost all the media takes on this issue.
  - monocasa 7y ago
    To be fair, that was the killer app of the space shuttle (ie. satellite interception and capture). We've lost that capability, and nothing on the medium term drawing board regains that.
    - thecount122195 7y ago
      You're right we don't currently, that just means its time to boot up space race 2, I hope China's space program kicks NASA back into high gear, shift a couple of the DOD's billions around and get space race 2 electric boogaloo going.
    - Robotbeat 7y ago
      Not true. SpaceX envisions using Starship (the same vehicle SpaceX would need to be able to launch 12,000 satellites) for satellite interception and capture. No Starship, no 12,000 satellites.
      - rtkwe 7y ago
        You don't need Starship for limited constellations to cause issues with Earth based observations though. Also SpaceX isn't the only one that's going to be wanting to make a constellation.
        Robotbeat 7y ago
        Well in that case, we've had limited constellations that cause issues for Earth based observations for decades. (Note: this is one hint that the risk here is exaggerated... dealing with satellites has been a thing for a very, very long time. Filtering out satellite tracks is easy and common, and modern digital imaging and data storage techniques have made satellite track removal ever easier. And many satellites--particularly space stations--are orders of magnitude brighter than Starlink satellites will be.)
- Robotbeat 7y ago
  ...with the kind of capabilities that enable megaconstellations (low cost launch, inexpensive space hardware replaced regularly every few years), neither of those things will be true. So either space astronomy becomes much easier/cheaper and we get megaconstellations, or megaconstellations won't happen.
  - rtkwe 7y ago
    Optics put a lot of design constrains on telescopes that mean they'll always be large items, when you're trying to look really far away at really dim objects you just need a lot of surface area to collect as much light as possible and the size of the object you can resolve is directly linked to the size of the aperture of the telescope you're using. Synthetic apertures using interferometry may solve that eventually but we're not there yet it looks like for really high resolution images.
    - Robotbeat 7y ago
      Right, I meant cost in terms of cost per unit dry mass, not just miniaturizing existing satellites. Starlink satellites are really cheap per unit dry mass, not just per satellite. Starship will be super cheap per unit dry mass, enabling ever-larger space telescopes. NASA even tweeted out one concept out for an aperture much larger than JWST using SpaceX's Starship: https://twitter.com/nasagoddard/status/1116310431969239040?lang=en https://twitter.com/nasagoddard/status/1116310431969239040?l...
      - rtkwe 7y ago
        They might get cheap to launch but they'll be quite expensive to build for the foreseeable future.
        Robotbeat 7y ago
        I don't see why they need to be. SpaceX has been able to reduce the cost of building space hardware with Starlink by an order of magnitude. When things are cheaper to launch, you can find ways to reduce the cost to build those things.

They're also much much more expensive and less flexible. With earth based satellites new experiments with new instrumentation is easy, in space currently we have no way to fix any issues.

thecount122195 7y ago
We can and have fixed space telescopes before, probably the most famous example is Hubble and its poor sight. https://en.wikipedia.org/wiki/Hubble_Space_Telescope#Flawed_mirror https://en.wikipedia.org/wiki/Hubble_Space_Telescope#Flawed_...
- rtkwe 7y ago
  We did but not any more 1) there's no longer anything like the shuttle available the only thing that could get close would take two launches to stage the parts and another for the crew capsule (not to mention most US capsules would have to evacuate the entire capsule to go outside iirc) and 2) most of the current space based telescopes like James Webb will be much much further out than Hubble was and most that get announced are also planned to orbit much further from Earth.
- kuschku 7y ago
  So which space shuttle should we use to fix James Webb if anything would go wrong after the launch? Currently no country has a well-working solution for that, nor does any company (not even SpaceX themselves)
  - sp332 7y ago
    JWST is for researching high-redshift object - the most distant things we can see in the universe. It's not a planet-hunter. And it will be much further away than other satellites, so they would be more easily serviced. (Not that it's easy, I just think you picked a bad example.)
    - privong 7y ago
      > JWST is for researching high-redshift object - the most distant things we can see in the universe. It's not a planet-hunter. JWST is a general purpose observatory. It will make significant advances for high-redshift objects. It will not survey large numbers of star for new planets, but it will be able to observe and characterize planets that have been identified by other missions/observatories.
  - mdorazio 7y ago
    Your comment assumes we still need fleshy meatbags wearing clunky suits in orbit to fix things. This was true 15 years ago, but I'm not convinced it's still true today. A couple of repair drones housed at the ISS combined with repair parts brought up along with normal resupply missions could probably be made to work if it was deemed cost effective.
    - plotteddancer16 7y ago
      This is a misconception. The ISS is not in an orbit that’s suitable for repairing satellites in other orbits.
    - rtkwe 7y ago
      The ISS isn't in a particularly good orbit because it's highly inclined (so Russia could easily launch to it) which is an expensive issue to fix dV wise unless all the target satellites are in a similarly inclined orbit. In terms of making them easy to swap out that's certainly possible but it will add weight compared to a monolithic satellite and so far we have very very little experience building and repairing things in space without using people.
    - dragonwriter 7y ago
      > could probably be made to work IOW, is a speculative, unproven idea.
  - Robotbeat 7y ago
    SpaceX is working on Starship, which should be capable of Shuttle-like service missions. (JWST is much more fragile than Hubble, however, so you'd need to build a custom servicing solution... but JWST is not representative of space telescopes generally.) In fact, SpaceX is counting on Starship to deploy their full constellation. No Starship, no 12,000 satellites.
    - rtkwe 7y ago
      I think JWST is going to look a lot like the future of space telescopes. There's hard requirements that make larger satellites better for observation, principally because larger aperture == better resolution and also because the larger mirror gathers more light so we can look at dimmer objects.
      - Robotbeat 7y ago
        It's not the size of JWST, it's the fact that it's deeply cryogenic and uses enormous, fragile multilayer insulation to remain so. Indeed, larger apertures will be used increasingly. And this megaconstellation actually enables that indirectly. SpaceX is counting on their Starship launch vehicle to deploy the vast majority of their 12,000 satellite constellation, and indeed large launch vehicles (particularly reusable ones) require a lot of payloads to justify their development cost. But large launch vehicles also enable ever-larger telescopes, whose cost is only affordable if those launch vehicles are reusable. NASA is already buying into it. Here's NASA Goddard tweeting out the larger-than-JWST concept called LUVOIR inside SpaceX's Starship (which again relies on the megaconstellation for demand): https://twitter.com/nasagoddard/status/1116310431969239040?lang=en https://twitter.com/nasagoddard/status/1116310431969239040?l... ...and yet larger apertures will require in-space assembly over several launches, again only really affordable if there's enough commercial launch demand (i.e. from megaconstellations in particular) to justify these large reusable launch vehicles. My point of view is that if we're going to be a really spacefaring civilization, it's reasonable that you'll be able to see human artifacts in the sky. Starlink is actually fairly easily stealthed, but other things (space based solar power stations, large space stations, in-space manufacturing depots, etc) may not be so easily hidden. Is the fact that human artifacts may be detectable in the night sky reason enough to disallow spacefaring? EDIT: Note that the IAU letter is way more reasonable than almost all the media takes on this issue.
- monocasa 7y ago
  To be fair, that was the killer app of the space shuttle (ie. satellite interception and capture). We've lost that capability, and nothing on the medium term drawing board regains that.
  - thecount122195 7y ago
    You're right we don't currently, that just means its time to boot up space race 2, I hope China's space program kicks NASA back into high gear, shift a couple of the DOD's billions around and get space race 2 electric boogaloo going.
  - Robotbeat 7y ago
    Not true. SpaceX envisions using Starship (the same vehicle SpaceX would need to be able to launch 12,000 satellites) for satellite interception and capture. No Starship, no 12,000 satellites.
    - rtkwe 7y ago
      You don't need Starship for limited constellations to cause issues with Earth based observations though. Also SpaceX isn't the only one that's going to be wanting to make a constellation.
      - Robotbeat 7y ago
        Well in that case, we've had limited constellations that cause issues for Earth based observations for decades. (Note: this is one hint that the risk here is exaggerated... dealing with satellites has been a thing for a very, very long time. Filtering out satellite tracks is easy and common, and modern digital imaging and data storage techniques have made satellite track removal ever easier. And many satellites--particularly space stations--are orders of magnitude brighter than Starlink satellites will be.)
Robotbeat 7y ago
...with the kind of capabilities that enable megaconstellations (low cost launch, inexpensive space hardware replaced regularly every few years), neither of those things will be true. So either space astronomy becomes much easier/cheaper and we get megaconstellations, or megaconstellations won't happen.
- rtkwe 7y ago
  Optics put a lot of design constrains on telescopes that mean they'll always be large items, when you're trying to look really far away at really dim objects you just need a lot of surface area to collect as much light as possible and the size of the object you can resolve is directly linked to the size of the aperture of the telescope you're using. Synthetic apertures using interferometry may solve that eventually but we're not there yet it looks like for really high resolution images.
  - Robotbeat 7y ago
    Right, I meant cost in terms of cost per unit dry mass, not just miniaturizing existing satellites. Starlink satellites are really cheap per unit dry mass, not just per satellite. Starship will be super cheap per unit dry mass, enabling ever-larger space telescopes. NASA even tweeted out one concept out for an aperture much larger than JWST using SpaceX's Starship: https://twitter.com/nasagoddard/status/1116310431969239040?lang=en https://twitter.com/nasagoddard/status/1116310431969239040?l...
    - rtkwe 7y ago
      They might get cheap to launch but they'll be quite expensive to build for the foreseeable future.
      - Robotbeat 7y ago
        I don't see why they need to be. SpaceX has been able to reduce the cost of building space hardware with Starlink by an order of magnitude. When things are cheaper to launch, you can find ways to reduce the cost to build those things.