what places in the solar system should we visit after mars and moon

[minerbat]

if you were the boss of an actual space agency, where would you go after mars and the moon because there are many more places in the solar system but you almost only hear about mars and the moon?

[tater]

2 minutes ago, minerbat said:

if you were the boss of an actual space agency, where would you go after mars and the moon because there are many more places in the solar system but you almost only hear about mars and the moon?

With humans? We've visited all the planets with robots (flybys), and many with orbiters.

For crew missions, the Moon is the only one we can visit any time soon due to travel times. Life support for even a Mars mission (dv needed is greater than a lunar trip, but comparable) is a non-trivial step from what we have now. The reason other planets are not typically considered for crew missions is basically for this reason. Travel times are much higher as you go out from Earth's orbit. Venus is a closer target, but crew cannot land there, so it's pretty pointless.

[sevenperforce]

2 minutes ago, tater said:

With humans? We've visited all the planets with robots (flybys), and many with orbiters.

For crew missions, the Moon is the only one we can visit any time soon due to travel times. Life support for even a Mars mission (dv needed is greater than a lunar trip, but comparable) is a non-trivial step from what we have now. The reason other planets are not typically considered for crew missions is basically for this reason. Travel times are much higher as you go out from Earth's orbit. Venus is a closer target, but crew cannot land there, so it's pretty pointless.

I'd suggest attempting a robot Venusian airship, just to see if it is feasible for humans someday.

But yeah, @tater is right: with current tech, we can't really send humans beyond Mars. Even a Ceres mission would be asking a lot; there's not enough gravity to do anything and you can't aerobrake so the dv requirements for a round trip are massive.

Good news is that developing tech to make Mars trips easier would be an enabler for outer solar system missions.

[minerbat]

3 minutes ago, tater said:

With humans? We've visited all the planets with robots (flybys), and many with orbiters.

For crew missions, the Moon is the only one we can visit any time soon due to travel times. Life support for even a Mars mission (dv needed is greater than a lunar trip, but comparable) is a non-trivial step from what we have now. The reason other planets are not typically considered for crew missions is basically for this reason. Travel times are much higher as you go out from Earth's orbit. Venus is a closer target, but crew cannot land there, so it's pretty pointless.

yes i mean manned but i also mean like 40 years in the future. also you cant land on venus but really high in the atmosphere the pressure and temperature are actually quite good so you can use a zappelin or hot air baloon.

alright, what about asteroids?

 

[sevenperforce]

1 minute ago, minerbat said:

alright, what about asteroids?

We'd be better off developing tech for using asteroids for solar lithopropulsion. Then you can bring the asteroids to the astronaut, rather than having to take the astronaut to the asteroid.

[tater]

16 minutes ago, sevenperforce said:

We'd be better off developing tech for using asteroids for solar lithopropulsion. Then you can bring the asteroids to the astronaut, rather than having to take the astronaut to the asteroid.

Yeah, better to grab a NEO asteroid, and drag it to Earth orbit, then use it. Visiting? What for?

I should add that while I'm a fan of human spaceflight---just because I think it's valuable to see humans exploring---there are limited places that make sense to send humans in the foreseeable future.

Missions to outer planets would certainly be awe-inspiring, but the technical challenges are huge. Take just the next world after Mars, Jupiter. A crew mission would take years. About as long as a round trip mission to Mars just to get to Jupiter. Doing it at all would likely be predicated on NTP being flown, or even a flavor of fusion. The craft would have to have a centrifuge for crew IMO, and radiation protection. What do the people do once they are there? The mass requirements for all of the above mean that the crew mission to Jupiter would likely fund some huge multiple of exploration capability using robots... there's just not a good case for it. Maybe in 100 years (200?).

[kerbiloid]

4 Vesta.

To say it hi!

Spoiler

 

[razark]

All of them, except Europa.

We should attempt no landing there.

[fulgur]

Nobody's mentioned Titan, which is my favourite moon. I think that we choose to go to Titan, not because it is easy, but because if you can lift 9% of your body weight (XKCD) you could fly! It has a low gravity but thick atmosphere, so would be very easy to land on and not that difficult, compared to Mars or Venus, to launch from - you could use propellers or airships, (links are to KSP craft) to launch out of the dense atmosphere and gain altitude & speed. You could also use the atmosphere to launch a wider exploration mission covering hundreds of km (unlike even the longest lasting rovers), because an electric-propeller plane or airship would be able to run indefinitely, even if it is far from the Sun. Or you could just get Near Future Electronics which has nuclear reactors in.

[adsii1970]

Asteroid Belt... For mining, industry, and colonization.

[kerbiloid]

Wiki says, Antarctica contains 30 mln km³ of ice.

That's a ~400 km ball.

So, we can easily make our own Minmus to fly there for skiing, skidding, and skating.

(Penguins can be relocated to the North, as anyway nobody can see them where they are now.)

Edited December 30, 2019 by kerbiloid

[Guest]

Titan would be great, except for one thing: it orbits Saturn. Which means it's too bloody far away to reach in 40 years. The ship needed to get there in reasonable time would be absolutely gigantic. It could be done, it definitely should be done at some point, but the sheer distance makes it a though goal. For the record, a minimum energy transfer to Saturn takes about as much dV as Earth liftoff to LEO. So, imagine that for whatever you want to send to Saturn, you need a to orbit full-size LV capable of sending your ship's mass to LEO. And that's just for a Hohmann transfer, which would take years to arrive. This explains why there was just one Saturn orbiter launched in the entire history of spaceflight (Cassini-Huygens, naturally). Compare this to a double-digit number of Mars orbiters, or a decent number of Venus missions.

Given this, I'd say Venus starts looking like an interesting near-term goal. 

[minerbat]

you can get to saturn more easy with gravity assist, the only problem is that it is only possible in specific times. also once we have build a larger moon base we can launch from there with way bigger payload and smaller rockets

[sevenperforce]

To get to the Jovian or Saturnian moons in a reasonable timeframe, you need to do a fast transfer, which has substantially greater dV requirements. To get the outgoing leg of a Hohmann transfer to Saturn, for example (suitable for a flyby), you need 7.3 km/s and the outgoing leg may take you as long as ten years without gravity assists. A fast transfer that gets you there in around two years will take 10-11 km/s from LEO. That extra 3-4 km/s is nothing to sneeze at.

And, of course, if you make your ship massively larger in order to shave off years of travel time, that also means you reach Saturn at dramatically higher speed. You can't aerobrake safely at those kinds of speeds, even in Titan's atmosphere (Saturn and Titan's gravity will add about 8.5 km/s to your interface velocity, which is about the limits of what a heat shield can tolerate even before adding in the relative closing velocity). So the faster your transfer, the more propellant you need to bring with you for the braking burn.

The only way to get that kind of propellant is to mine it out of lunar ice. Of course, departing from the moon rather than from LEO adds more dV to the exit burn. You really need lunar ISRU and either a big NTR or Z-pinch fusion if you want to get to Saturn in a reasonable time.

 

[Bill Phil]

Hmm...

40 years from now?

Mini-Mag Orion could enable expeditions to Jupiter and Saturn. 

Then maybe develop some kind of beamed propulsion (either mass beam or photon beam, though mass beam propulsion is more efficient and I’ve seen proposals for beam-assisted Mini-Mag Orion) to get higher velocities with known technology and no extreme fusion tech. What’s cool is that this can lead to rapid interplanetary transport and could be a potential development path for interstellar propulsion as well.

[kerbiloid]

We must visit 67/P to save Philae and Rosetta and bring them back to home.

And catch Pioneers and Voyagers before they can reveal our safe vault to the aliens.

Edited December 31, 2019 by kerbiloid

[Scotius]

What should we visit? Everything

What can we visit? Not much at this point

We do have technology to reach Moon. We might have the technology to reach Mars. But what else?

Venus is hell. For centuries to come her surface will be domain of heavy duty robotic probes. Is studying Venusian atmosphere important enough to require human presence? I doubt it.

Mercury is deep in Solar gravity well. It's costly to reach in dV terms - even costlier to return from there, fighting against Sun's gravitational pull. And you better haul robust cooling systems along

Gas giants are far. To reach them we will need nuclear or fusion engines, advanced electric propulsion or even something more exotic than we have today.

So what's left? Asteroids. And short period comets. That's pretty much it.

Edited December 31, 2019 by Scotius

[minerbat]

phobos and deimos could be good bases for mars exploration?

[kerbiloid]

42 minutes ago, Scotius said:

Is studying Venusian atmosphere important enough to require human presence? I doubt it.

A motivational-inspirational idea for the Venus (just a thought, not a claim).

As it has a lot of sulfic acid in air, it was a significant flow of sulfides from beneath up to ground.
Let's imagine there is a lot of sulfide ore underground geothermal deposits there, and we can mine Cu/Pb/Ag/Hg/Sn/Zn and send this to the Earth.

Let the greed lead us there!

[minerbat]

this is probably more far future but venus could actually be better for terraforming than mars

[RealKerbal3x]

5 hours ago, minerbat said:

this is probably more far future but venus could actually be better for terraforming than mars

A lot of the stuff in Venus' atmosphere solidifies at Earth-type temperatures, which means you'll probably have a kilometre-thick drift of solid sulfur and other elements over the whole surface.

Mars' atmosphere is mostly CO2, which will remain a gas even when the Martian environment is heated up to Earth surface temperatures - much less of a problem than Venus.

Edited December 31, 2019 by RealKerbal3x

[minerbat]

1 hour ago, RealKerbal3x said:

A lot of the stuff in Venus' atmosphere solidifies at Earth-type temperatures, which means you'll probably have a kilometre-thick drift of solid sulfur and other elements over the whole surface.

Mars' atmosphere is mostly CO2, which will remain a gas even when the Martian environment is heated up to Earth surface temperatures - much less of a problem than Venus.

that is not true. venus atmosphere is 96,5% CO2 and the rest is mostly nitrogen and only a very tiny percentage is SO2. you could use GM microbes to make oxygen out of carbon dioxide.

[Scotius]

36 minutes ago, minerbat said:

you could use GM microbes to make oxygen out of carbon dioxide.

Funny you would mention this...

https://www.discovermagazine.com/environment/scientists-just-created-a-bacteria-that-eats-co2-to-reduce-greenhouse-gases

Doubtful if it can survive on Venus, but the first step has been made

[magnemoe]

For manned missions I would focus on asteroids after Mars, might even do an larger near earth asteroide before Mars but with starship Mars is more likely.
Only reason to go to Venus is if you want to have crew in orbit to manage something like an rover or surface sample return mission there the light speed lag is an serious issue. 
Jupiter or Saturn would be next of the bucket list after various asteroids. Here you will need something better than starship however. 

[magnemoe]

17 hours ago, kerbiloid said:

We must visit 67/P to save Philae and Rosetta and bring them back to home.

And catch Pioneers and Voyagers before they can reveal our safe vault to the aliens.

That is another issue, grabbing various legacy stuff will be an future game. Recover Snoopy and grab one of the moon lander landing stage and assemble is probably the main price  
Legality is an bit questionable here, however that just make you an space pirate who is pretty awesome if you can use it as an title. 

http://freefall.purrsia.com/ff1400/fc01345.htm