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Just launch a deep-space telescope; it would be easier. Soft-landing the telescope on an airless body would be harder (in delta-V terms) than just launching it

Just launch a deep-space telescope; it would be easier. Soft-landing the telescope on an airless body would be harder (in delta-V terms) than just launching it into an equivalent solar orbit. And the body would block about half your view of the sky at any one time.

jbay808 5y ago
Could you get a nice gravity boost away from the sun by just following it for as long as possible?
- jstanley 5y ago
  I think the point is that in order to follow it, you need to (at some point in time) be at the same place and with the same velocity. Then you'll follow it. But the energy required to do that is almost the same as what it would be if the dwarf planet wasn't there. You could get onto exactly the same orbit for roughly the same amount of energy, and if you relax the requirement that there be a dwarf planet nearby, you can choose superior orbits.
- lamontcg 5y ago
  No, that's not how gravity boosts work. If you match speeds with an object you actually get zero boost. The point of a gravity boost is to come in pretty hot (relative to the body you're boosting off of) and then go out pretty hot in a different direction. So you take your relative velocity vector at the point of the encounter and twist it around. By doing that you change your orbital energy around your central body (the sun) by a lot, and the other object will lose a similar amount to keep the bookkeeping equal. If you have zero relative velocity compared to the thing you want a gravity assist off of you can't get an assist. It isn't like drafting a semi.
  - geenew 5y ago
    Could there be some energy advantage to being in orbit around it? I'm thinking of a scenario where you spend a large amount of energy once get into orbit around the object, but then gain a small amount of energy continuously through something like tidal forces.
    - lamontcg 5y ago
      Everything else is going to be small and average out over time. And if you manage to pick up a bit of energy orbiting a tiny object you'll quickly just get ejected at its (small) escape velocity. Whatever that gives you, it won't be worth the cost of matching orbits to start with. Better to come in hot and slingshot. Solar wind / radiation pressure is probably the next best free ride since that adds up over time continuously and is everywhere.
  - stnmtn 5y ago
    Interesting, do you mind explaining how the "other object will lose a similar amount"? I find orbital mechaics fascinating and understand the concept of a slingshot, but I can intuitively understand how if we launched a rocket and slingshotted it around the moon, the moon would be affected by that
- 0-_-0 5y ago
  I think it should provide a much stronger slingshot velocity boost than any other planet, however getting to 11AU first is not easy. https://en.wikipedia.org/wiki/Gravity_assist https://en.wikipedia.org/wiki/Gravity_assist
  - btilly 5y ago
    For the best gravity assist you want to have a large delta V, and you want to come in on a hyperbolic orbit that causes you to turn by 90 degrees. This object has all of the delta V that you could want, but for an object of that mass, the hyperbolic orbit would require going through the planetoid which you can't do. And if it was dense enough that you could (for example a miniature black hole), the tidal forces during the turn would be insane. So no, this object cannot give a decent slingshot.
  - simonh 5y ago
    The magnitude of the slingshot boost increases with the mass of the planetary body. This thing is smaller than any of the planets so you’d get a much smaller boost. The best planet for slingshotting from is Jupiter because it’s the most massive.
- _Microft 5y ago
  The easiest way to think about this is as perfectly elastic collision between the spacecraft and the planet (mediated by gravity, but this is an unnecessary detail already).

jbay808 5y ago

Could you get a nice gravity boost away from the sun by just following it for as long as possible?

jstanley 5y ago
I think the point is that in order to follow it, you need to (at some point in time) be at the same place and with the same velocity. Then you'll follow it. But the energy required to do that is almost the same as what it would be if the dwarf planet wasn't there. You could get onto exactly the same orbit for roughly the same amount of energy, and if you relax the requirement that there be a dwarf planet nearby, you can choose superior orbits.
lamontcg 5y ago
No, that's not how gravity boosts work. If you match speeds with an object you actually get zero boost. The point of a gravity boost is to come in pretty hot (relative to the body you're boosting off of) and then go out pretty hot in a different direction. So you take your relative velocity vector at the point of the encounter and twist it around. By doing that you change your orbital energy around your central body (the sun) by a lot, and the other object will lose a similar amount to keep the bookkeeping equal. If you have zero relative velocity compared to the thing you want a gravity assist off of you can't get an assist. It isn't like drafting a semi.
- geenew 5y ago
  Could there be some energy advantage to being in orbit around it? I'm thinking of a scenario where you spend a large amount of energy once get into orbit around the object, but then gain a small amount of energy continuously through something like tidal forces.
  - lamontcg 5y ago
    Everything else is going to be small and average out over time. And if you manage to pick up a bit of energy orbiting a tiny object you'll quickly just get ejected at its (small) escape velocity. Whatever that gives you, it won't be worth the cost of matching orbits to start with. Better to come in hot and slingshot. Solar wind / radiation pressure is probably the next best free ride since that adds up over time continuously and is everywhere.
- stnmtn 5y ago
  Interesting, do you mind explaining how the "other object will lose a similar amount"? I find orbital mechaics fascinating and understand the concept of a slingshot, but I can intuitively understand how if we launched a rocket and slingshotted it around the moon, the moon would be affected by that
0-_-0 5y ago
I think it should provide a much stronger slingshot velocity boost than any other planet, however getting to 11AU first is not easy. https://en.wikipedia.org/wiki/Gravity_assist https://en.wikipedia.org/wiki/Gravity_assist
- btilly 5y ago
  For the best gravity assist you want to have a large delta V, and you want to come in on a hyperbolic orbit that causes you to turn by 90 degrees. This object has all of the delta V that you could want, but for an object of that mass, the hyperbolic orbit would require going through the planetoid which you can't do. And if it was dense enough that you could (for example a miniature black hole), the tidal forces during the turn would be insane. So no, this object cannot give a decent slingshot.
- simonh 5y ago
  The magnitude of the slingshot boost increases with the mass of the planetary body. This thing is smaller than any of the planets so you’d get a much smaller boost. The best planet for slingshotting from is Jupiter because it’s the most massive.
_Microft 5y ago
The easiest way to think about this is as perfectly elastic collision between the spacecraft and the planet (mediated by gravity, but this is an unnecessary detail already).