

NASA: Let's Explore Venus in Solar Zeppelins and Build a Cloud City - stevenjgarner
http://sacd.larc.nasa.gov/branches/space-mission-analysis-branch-smab/smab-projects/havoc/

======
stevenjgarner
Could Venus be a more enticing option for an upcoming manned mission than
Mars? Not having to perform descent and subsequent launch, such a mission
presumably could be done for a fraction of the cost of a Mars mission.

~~~
dalke
There are three possible mission plans I know of for Venus. 1) Venus flyby,
like what was planned in the 1970s with Apollo hardware. 2) Orbit Venus, and
3) this one to descend into the atmosphere.

For Mars there are four: 1) flyby, 2) orbit, 3) land on one of the Martian
moons, 4) land on Mars. The latter has a variant: Zubrin proposed that we can
make rocket fuel on Mars and use that for the ascent and/or return.

Of these, I don't see why a flyby does anything other than say we did it. Our
automated probes are now much more capable than we had in the 1960s/1970s.
Though if a human were useful, the Venus is definitely quicker to get to than
Mars.

As far as I can tell, it's about the same amount of delta-v to get to Mars as
Venus, so orbiting either is possible, except the longer flight time for Mars
and back means a lot more extra supplies (something like 5kg/day * 14 months?)
and more risk of something going wrong. Venus comes out ahead.

But what does a human orbiting either planet add that a robotic probe does
not?

The most often given example is fast response time for a rover, since it's at
least a 4 minute lag for Venus and 6 minutes for Mars. I would rather have a
dozen slow rovers on the ground controlled from Earth, or a dozen long-term
probes orbiting the gas giants than a single one by a human above Venus. In
any case, we know we can put capable rovers on Mars. On Venus they tend to
melt.

This one to descend into the atmosphere of Venus means a return vehicle almost
as powerful as what's needed to get someone off Earth. That's going to be
tough to solve. Our biggest balloon launched rockets are, I believe, from
amateur organizations. OTOH, robots don't need to come back to Earth.

Landing on a moon of Mars would combine Mars observations and visual
exploration of (what's believed to be) an asteroid. Though it would be easier
if we go to a near Earth asteroid instead.

In the balance of things, I think Mars is still more enticing. Though I'm
definitely in the robot probe camp.

And I would much rather have people on the Moon again, since my hopeful belief
is that trained geologists on the ground for a full lunar day would be more
capable than the equivalent cost in robots at understanding lunar geology. (I
ask myself though if it's worth the 1% chance of death.)

