Places humans can explore in the solar system

[Drbuzz0]

Wondering if anyone has any different ideas on this one or any thoughts. I've recently started thinking about the issue of where humans could go. Mars is the obvious next step in space exploration, and of course asteroids are a possibility too. But what after that? Surely humans can survive flybys of most of the bodies in the solar system. The more distant areas would require some kind of heat source (probably nuclear) but what about landing?

Here's my list. Feel free to disagree. Basically it comes down to what a reasonable space suit could be expected to protect one from, because just landing there in a super-heavy armored pressure vessel seems rather non-useful.

Mercury: Maybe on the cool side, for a limited time at least. On the side facing the sun would be difficult. Maybe with large sun shades to protect astronauts for a brief period of time.

Venus: Unlikely. A very hard, very pressure and heat resistant suit would be necessary. Extremely robust heat rejection system. The only probes that ever landed on Venus functioned only a short period of time. Venus is probably a no-go.

Earth's moon: Yes. It's been done.

Asteroids: Yes. Of course, deep space exploration would have other issues to contend with, like radiation shelters for sun storms, but there's nothing about an asteroid that makes it impossible to explore by humans. Would be difficult to stay on surface due to limited gravity, so it would not necessarily be "walking" on it so much as clinging to it.

Comets: Probably not, unless very distant from the sun and thus very cold. They spew out a lot of vapor, debris and so on. Not an appealing place for humans.

Mars: Yes.

Moons of Mars (Phobos and Deimos): Yes, but again, small size and thus gravity makes motion and maneuvering an issue. Not simple to "walk on"

Major moons of Jupiter: Maybe or Probably. Nuclear heat source for human habitation would likely be necessary. There is a thin atmosphere which contains oxygen that could potentially be extracted, which would be an interesting possibility. Space suits beyond the current capabilities would likely be necessary, but not impossible. Some areas may have hazards that would be beyond current systems.

Major Moons of Saturn: Maybe. Even colder than those of Jupiter. Similar hazardous areas, but possible some areas could be habitable.

The gas giants: No. You would die very quickly.

Pluto and keiper belt planetoids: Maybe. Again, very cold. The big issue would be getting a crew to and from them. Presumably not a good place for a settlement, so a one-way trip would be something nobody seems likely to want. Extreme distance would be the big problem with current technology.

[Noclevername]

For Mercury, landing at a perma-shadowed crater at the poles could be doable. It would give us the opportunity to look for traces of volatiles there.

For Venus, it's been suggested that we could float a balloon at the 1-bar atmosphere level. Perhaps the same could be done at higher altitudes on some of the tamer gas giants.

Still, it'll probably be quite a while before we send humans to most of these places, so current travel and life support technology limits might not be as much of a problem by then.

[Romanus]

Mercury wouldn't be too difficult (once you get past the energy it takes to get there and the insolation at that distance, of course). The temperatures at the terminator would not be bad, and a sunshade would mitigate much of the heat, as would insulated boots (as Hartmann et al. point out in Out of the Cradle, Mercury has no atmosphere to convey heat).

[Noclevername]

I foresee... aerogel elevator shoes!

[galacsi]

Wondering if anyone has any different ideas on this one or any thoughts. I've recently started thinking about the issue of where humans could go. Mars is the obvious next step in space exploration, and of course asteroids are a possibility too. But what after that? Surely humans can survive flybys of most of the bodies in the solar system. The more distant areas would require some kind of heat source (probably nuclear) but what about landing?

Here's my list. Feel free to disagree. Basically it comes down to what a reasonable space suit could be expected to protect one from, because just landing there in a super-heavy armored pressure vessel seems rather non-useful.
. . . .

Major moons of Jupiter: Maybe or Probably. Nuclear heat source for human habitation would likely be necessary. There is a thin atmosphere which contains oxygen that could potentially be extracted, which would be an interesting possibility. Space suits beyond the current capabilities would likely be necessary, but not impossible. Some areas may have hazards that would be beyond current systems.

. . .

The radiation belts of Jupiter are much more powerfull than the Earth's ones and the three inners Galileans moons are bathing in it. Only Callisto IMO ,could be reached safely.

[Bynaus]

Mercury

As has been said by others, the poles are quite okay for human visitors. There are certain locations where the surface temperature is always around 300 K. Mercury would definetly be a good target for human exploration - one day.

Venus

Not the surface, obviously, but above the cloud-top, one of the most Earth-like environements of the solar system (apart from Earth) can be found: ca. 1 bar pressure, ca. 300 K (actually, the 300 K level is at about 0.5 bar), only light acid drops and an inert atmosphere of CO2 - but with abundant sunlight, from above and (reflected) below. Scientific exploration airships? You guess!

Asteroids

I think the large asteroids, like Ceres, Vesta and Pallas, would make good exploration targets as well. Ceres seems to have abundant water, which is good for a lot of reasons (building, propulsion, shielding). A manned mission to Ceres would certainly be worthwile - one day.

Major moons of Jupiter

As pointed out above, radiation hazard would be a serious problem for all the galilean satellites except Callisto. But this world is good for the same reasons as Ceres, however its sitting quite deep in the second-largest gravity-well of the solar system. One should not dismiss the irregular satellites though - if we can go to asteroids, we will be able to go there as well.

Major Moons of Saturn

Titan would certainly be an interesting target. No pressure suits required! The thick atmosphere would enable aerocapture, which is a big plus if you want to deliver large payloads. Iapetus is a nice target as well, as it orbits quite far out and is relatively large (similar to Ceres). At Saturn, I guess nuclear energy sources become a must.

[Trebuchet]

Earth's moon: Yes. It's been done.

Only on a soundstage in Area 51, with Stanley Kubrick directing!

There was an early Larry Niven story called, IIRC, The Coldest Place, about landing on the dark side of Mercury, which was thought at the time to be tidally locked to the sun.

[Ara Pacis]

Mercury wouldn't be too difficult (once you get past the energy it takes to get there and the insolation at that distance, of course). The temperatures at the terminator would not be bad, and a sunshade would mitigate much of the heat, as would insulated boots (as Hartmann et al. point out in Out of the Cradle, Mercury has no atmosphere to convey heat).

What about conduction and radiant heat from the surface? I assume that if you're using a sunshade, you must be on the sunny-side.

[KaiYeves]

I foresee... aerogel elevator shoes!

The hottest fashion trend of the future!

[Jens]

The sun

Of course we'd have to go at night, otherwise it would be too hot.

[KaiYeves]

The sun

Of course we'd have to go at night, otherwise it would be too hot.

Aw, don't you know the sun is useless? It shines during the day when it's light out already! Now the moon, the moon is good for something...

[samkent]

I wonder how large the Sun would appear during the day on Mercury?
As big as our Full Moon?? Larger?

[samkent]

I answered my own question with a nice link.
http://messenger-education.org/elusi...fastfact_1.php

[Jens]

I wonder how large the Sun would appear during the day on Mercury?
As big as our Full Moon?? Larger?

Just the answer the part about the moon, from earth the sun and moon appear to be about the same size, which is why the moon sometimes can eclipse the whole sun (a total eclipse) but sometimes is too small and can only eclipse the inner part (an annular eclipse). It's an interesting coincidence that the two happen to be so similar in size for us. So given that the sun would be bigger from Mercury, it would also be much bigger than the full moon.

[Romanus]

Re Ara Pacis:
Insulation would (hopefully) take care of the heat of the surface. Reflected glare would probably require additional insulation and *heavy* duty filters. It's no Venus, though. The best solution would be to land near the terminator, which if I'm not mistaken was pretty much the approach taken by the Apollo missions, for both heat avoidance and lighting purposes (the shadows highlighted potential pitfalls).

[NEOWatcher]

I wonder how large the Sun would appear during the day on Mercury?
As big as our Full Moon?? Larger?

Earth to sun
~150M km
Mercury to sun
~57M km
150/57 = 2.6 times bigger

[Ara Pacis]

Re Ara Pacis:
Insulation would (hopefully) take care of the heat of the surface. Reflected glare would probably require additional insulation and *heavy* duty filters. It's no Venus, though. The best solution would be to land near the terminator, which if I'm not mistaken was pretty much the approach taken by the Apollo missions, for both heat avoidance and lighting purposes (the shadows highlighted potential pitfalls).

It's 800 F on the sunny side, insulation will slow heat gain down, but it won't stop it forever, and the days on Mercury are looooong.