Hello Pluto

[mistermack]

Once nuclear fusion has been cracked, all of these places will be viable for humans to exploit.
It may be a long way from the Sun, but if there is water there, that's all we will need to make a nice snug home there.

It's entirely possible that there are bigger bodies further out. We have no way of knowing.
There could easily be Earth-sized bodies in the Oort cloud. They would be impossible to detect, and their gravity might be responsible for throwing some of the comets in our direction.

Actually though, from an exploitation point of view, things the size of Pluto are ideal, as you can land and take off from them with very little energy, and yet they are big enough to be mined for materials. Something the size of Earth would be a major challenge, compared to a Pluto.

[Xamonas Chegwé]

Once nuclear fusion has been cracked, all of these places will be viable for humans to exploit.
It may be a long way from the Sun, but if there is water there, that's all we will need to make a nice snug home there.

It's entirely possible that there are bigger bodies further out. We have no way of knowing.
There could easily be Earth-sized bodies in the Oort cloud. They would be impossible to detect, and their gravity might be responsible for throwing some of the comets in our direction.

Actually though, from an exploitation point of view, things the size of Pluto are ideal, as you can land and take off from them with very little energy, and yet they are big enough to be mined for materials. Something the size of Earth would be a major challenge, compared to a Pluto.

Living on a planet that size would cause physiological problems. Long periods of low gravity cause skeleto-muscular problems and possibly other conditions.

[JimC]

Once nuclear fusion has been cracked, all of these places will be viable for humans to exploit.
It may be a long way from the Sun, but if there is water there, that's all we will need to make a nice snug home there.

It's entirely possible that there are bigger bodies further out. We have no way of knowing.
There could easily be Earth-sized bodies in the Oort cloud. They would be impossible to detect, and their gravity might be responsible for throwing some of the comets in our direction.

Actually though, from an exploitation point of view, things the size of Pluto are ideal, as you can land and take off from them with very little energy, and yet they are big enough to be mined for materials. Something the size of Earth would be a major challenge, compared to a Pluto.

Living on a planet that size would cause physiological problems. Long periods of low gravity cause skeleto-muscular problems and possibly other conditions.

Certainly long periods in orbit, with virtually zero gravity, has that effect. However, it is possible that you don't need full Earth gravity to keep healthy - 20% may be enough, especially given a well-planned exercise regime.

[Xamonas Chegwé]

Once nuclear fusion has been cracked, all of these places will be viable for humans to exploit.
It may be a long way from the Sun, but if there is water there, that's all we will need to make a nice snug home there.

It's entirely possible that there are bigger bodies further out. We have no way of knowing.
There could easily be Earth-sized bodies in the Oort cloud. They would be impossible to detect, and their gravity might be responsible for throwing some of the comets in our direction.

Actually though, from an exploitation point of view, things the size of Pluto are ideal, as you can land and take off from them with very little energy, and yet they are big enough to be mined for materials. Something the size of Earth would be a major challenge, compared to a Pluto.

Living on a planet that size would cause physiological problems. Long periods of low gravity cause skeleto-muscular problems and possibly other conditions.

Certainly long periods in orbit, with virtually zero gravity, has that effect. However, it is possible that you don't need full Earth gravity to keep healthy - 20% may be enough, especially given a well-planned exercise regime.

Here's an interesting article.

http://www.wired.com/2014/02/happens-body-mars/

[klr]

There was an hour-long Sky at Night special last night, but I missed the first half. I'll catch the re-run later this week.

[JimC]

Once nuclear fusion has been cracked, all of these places will be viable for humans to exploit.
It may be a long way from the Sun, but if there is water there, that's all we will need to make a nice snug home there.

It's entirely possible that there are bigger bodies further out. We have no way of knowing.
There could easily be Earth-sized bodies in the Oort cloud. They would be impossible to detect, and their gravity might be responsible for throwing some of the comets in our direction.

Actually though, from an exploitation point of view, things the size of Pluto are ideal, as you can land and take off from them with very little energy, and yet they are big enough to be mined for materials. Something the size of Earth would be a major challenge, compared to a Pluto.

Living on a planet that size would cause physiological problems. Long periods of low gravity cause skeleto-muscular problems and possibly other conditions.

Certainly long periods in orbit, with virtually zero gravity, has that effect. However, it is possible that you don't need full Earth gravity to keep healthy - 20% may be enough, especially given a well-planned exercise regime.

Here's an interesting article.

http://www.wired.com/2014/02/happens-body-mars/

It was interesting, but all the bad effects related to gravity mentioned in the article are specifically linked to zero gravity conditions. Of course, this would be an issue on the journey to Mars, but there is no evidence one way or another as to whether the bad effects would still emerge in a situation where there was at least some gravity, albeit weaker than Earth's.

[Xamonas Chegwé]

It was interesting, but all the bad effects related to gravity mentioned in the article are specifically linked to zero gravity conditions. Of course, this would be an issue on the journey to Mars, but there is no evidence one way or another as to whether the bad effects would still emerge in a situation where there was at least some gravity, albeit weaker than Earth's.

I thought similar. Although one would expect the harmful effects to increase gradually as gravity decreases, rather than a catastrophic event when gravity reaches zero. Hard to test without a moonbase, really.

[mistermack]

There was a whole Horizon program on just before the Sky at Night, about the project to send people to Mars. They didn't dwell on the gravity problem, they were quite upbeat about the prospects. I would say in a totally unrealistic fashion.

Kevin Fong doesn't mention in his article that at rotation levels of less than 2 rpm, people don't notice the inner ear effects at all, so you can spin the space ship at that rate, and none of your passengers will get dizzy. Below that rate, some will notice, some more, some less.

At 2rpm, you need to be 100 metres from the centre, to experience half a g.
Half of a g might be enough, when combined with a rigorous excercise regime, to keep an adult reasonably healthy for long periods.

If you want to provide 1 full g of gravity, you need to spin about a 220 metre radius at 2 rpm.

Although that sounds like a big space station, it's not big in the general run of things that humans build. If you built a 200 m tube, with living quarters at both ends and all of the technical stuff in between, It could be spun up to 2rpm fairly easily, and needn't be much bigger than a commuter train. That would provide half a g in the living area.

That would be a huge project today as they have to lift every component up from the Earth. But, if they concentrate on making use of the Moon for materials, and manufacturing stuff on the Moon's surface, or on a space station, then it wouldn't be such a huge job.
The huge jump in progress will come when people start to make stuff out of Moon materials.
After that, space projects will grow exponentially in size and scope.

The biggest problem, with Mars, is landing and taking off again. Mars is so far away, you have to get up to very high speeds to get there in a reasonable time. So when you arrive, you have to scrub off a huge amount of speed. The Moon is so much closer, you can go a lot slower, and it makes it easier to slow down. And then the Surface gravity on Mars is Double that of the Moon, so you need far more rocket power to get down safely, and take off again.

So I reckon that Mars is a non-starter, till long after we are living, working and manufacturing on the Moon. So that's what they should be concentrating on, and forget Mars, till we have the technology to do it easily.

[trdsf]

I just love the hell out of the latest: frozen nitrogen glaciers. You couldn't make this shit up. Well, you could, but I wouldn't want to be the one to have to work it into a narrative.

[mistermack]

I just love the hell out of the latest: frozen nitrogen glaciers. You couldn't make this shit up. Well, you could, but I wouldn't want to be the one to have to work it into a narrative.

Nitrogen must be very slushy ice, or a very weak ice, to flow on Pluto, with it's super low gravity.
Or maybe something is still happening internally causing a lot of Plutoquakes, and the vibration allows the ice to flow.

[JimC]

When do we get to see some Plutonians?

[mistermack]

When do we get to see some Plutonians?

Have you tried magic mushrooms?

[JimC]

I lived on 'em in the 70s...

[mistermack]

I lived on 'em in the 70s...

Aaaaaaaah.

That explains a lot.

[klr]

There was a whole Horizon program on just before the Sky at Night, about the project to send people to Mars. They didn't dwell on the gravity problem, they were quite upbeat about the prospects. I would say in a totally unrealistic fashion.

Kevin Fong doesn't mention in his article that at rotation levels of less than 2 rpm, people don't notice the inner ear effects at all, so you can spin the space ship at that rate, and none of your passengers will get dizzy. Below that rate, some will notice, some more, some less.

At 2rpm, you need to be 100 metres from the centre, to experience half a g.
Half of a g might be enough, when combined with a rigorous excercise regime, to keep an adult reasonably healthy for long periods.

If you want to provide 1 full g of gravity, you need to spin about a 220 metre radius at 2 rpm.

Although that sounds like a big space station, it's not big in the general run of things that humans build. If you built a 200 m tube, with living quarters at both ends and all of the technical stuff in between, It could be spun up to 2rpm fairly easily, and needn't be much bigger than a commuter train. That would provide half a g in the living area.

That would be a huge project today as they have to lift every component up from the Earth. But, if they concentrate on making use of the Moon for materials, and manufacturing stuff on the Moon's surface, or on a space station, then it wouldn't be such a huge job.
The huge jump in progress will come when people start to make stuff out of Moon materials.
After that, space projects will grow exponentially in size and scope.

The biggest problem, with Mars, is landing and taking off again. Mars is so far away, you have to get up to very high speeds to get there in a reasonable time. So when you arrive, you have to scrub off a huge amount of speed. The Moon is so much closer, you can go a lot slower, and it makes it easier to slow down. And then the Surface gravity on Mars is Double that of the Moon, so you need far more rocket power to get down safely, and take off again.

So I reckon that Mars is a non-starter, till long after we are living, working and manufacturing on the Moon. So that's what they should be concentrating on, and forget Mars, till we have the technology to do it easily.

Even just getting into orbit would be fun. Aerobraking would seem to be the preferred method.