Uranus Orbiter, The other proposed ice-giant mission Options

[Rob Pinnegar]

Since the Neptune Orbiter thread has started to veer into talking about a Uranus orbiter as well, it seemed like a good idea to start a topic for Uranus.

[Guest_BruceMoomaw_*]

Just keep in mind that -- because Pluto's gravity is so weak -- its atmosphere, thin though it is, towers up and up and up above the surface, with a huge scale height. In fact, there is speculation that some of it may get exchanged with Charon through tidal forces! High-altitude aerocapture in this situation is quite practical, if you have a moderately-sized ballute. (Ditto for Triton.)

[tasp]

Just keep in mind that -- because Pluto's gravity is so weak -- its atmosphere, thin though it is, towers up and up and up above the surface, with a huge scale height.  In fact, there is speculation that some of it may get exchanged with Charon through tidal forces!  High-altitude aerocapture in this situation is quite practical, if you have a moderately-sized ballute.  (Ditto for Triton.)

I noted with interest in the referenced paper on the ballutes the one with a lens shape.

If this is not an original idea with me, my apologies; could such a near disk shaped ballute be angled during decel ? That advantage might be that a craft could manuever during the deceleration phase. The force applied by the ballute to the craft would not have to pass through the center of mass of the craft. The effect would be usable lift. The decel phase could be prolonged at a higher altitude while the craft arced further around the target object. Regions that perhaps would not be accessable from the 'standard' ballute might be reachable with a steerable one.

Should Pluto (or whatever) not be favorably aligned at arrival, this technique might still get you were you want to go.

Perhaps the decel could start over the far side (as seen from earth) and wind up on the fore side for the actual landing phase.

Another application might be (again using Pluto as an example) to enter the deceleration phase where convenient from the arrival trajectory, and manuver during decel and then exit the atmosphere on a path that leads to Charon (at a low enough speed that perhaps you could orbit or land there).

An application at Triton might be to decel in its' atmosphere, but not so much as to be captured by it, and wind up in an orbit favorably inclined about Neptune.

Aerocapture into Saturn orbit via ballute passage through Titan's atmosphere seems doable. Perhaps the manuvering technique would put the craft into an equatorial orbit about Saturn (for example) from a greater variety of incoming trajectory angles than any other technique?