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.

[dvandorn]

The biggest problem with using steerable aerocapture / landing trajectories is that you need to have a *very* good model of the atmosphere you're using to slow down with.

It's bad enough to have only a vague idea of the temperature/pressure profile of an atmosphere you're using to do straight-line drag braking. If you're designing into your spacecraft and trajectory a need for predictable changes in direction based on lift, *any* significant variation in the atmosphere's pressure, density and temperature profile from your model will result in completely different results.

They're talking about needing a Mars orbiter for day-to-day monitoring of the upper atmosphere in order to successfully land future probes -- apparently, Mars' upper atmosphere was so much thinner and extended than predicted during Spirit's EDL that she was very nearly dashed against the surface a la Beagle II. Cassini is seeing that Titan's upper atmosphere also seems highly variable in pressure/altitude. So, in order to successfully use Titan aerobraking for a Saturn orbiter, you'd almost need to already have a working Saturn orbiter there to tell you the detail you need about Titan's atmosphere at that moment...

Like many other elegant ideas, this one tends to fall apart when you look at it in greater detail.

-the other Doug