Big Water On Mars!

[Onyx]

That articles is only putting cosmic rays forward as a problem during the voyage between Earth and Mars and the relevant post was only concerned with radiation on Mars itself. Now I'm not denying that radiation protection will be necessary on the surface of Mars, of course it will and I've always considered it the greatest problem to any kind of habitation there. However regarding Galactic Cosmic Rays (GCRs) NASA seem to be focused on the voyage rather Mars itself and there they have some intriguing ideas up their sleeves:
How to Protect Astronauts from Space Radiation on Mars

I realize what the article is about, but the point the article makes is that both Galactic and Solar cosmic rays are dangerous. And the point I made is that building a lagrange magnetic shield against just Solar cosmic rays isn't going to shield those on the surface of Mars from Galactic cosmic rays.

What will shield people on Mars from both kinds are thick building materials, since there is no magnetosphere or real atmosphere. So given the need for GCR shielding that would also block SCR, why would anyone construct a huge magnetic shield for just the SCR when it doesn't solve the radiation problem?

I just don't understand the point of the lagrange shield you mentioned since it doesn't make anything safe on Mars. It's like an umbrella with a big hole.

 

[Justin Swanton]

I suspect that if NASA gets the funding to keep people on Mars for long periods of time then it needs to find a few good caves. That's the cheapest (i.e. cost-free) way of getting the protection you need. The thing is to find the caves and that's what rovers are for.

To misquote Genesis: from the cave you emerged and to the cave you will return.

 

[BAYLOR]

I suspect that if NASA gets the funding to keep people on Mars for long periods of time then it needs to find a few good caves. That's the cheapest (i.e. cost-free) way of getting the protection you need. The thing is to find the caves and that's what rovers are for.

To misquote Genesis: from the cave you emerged and to the cave you will return.

Sustainability of colony . That's where it gets complicated and costly.

 

[Onyx]

I suspect that if NASA gets the funding to keep people on Mars for long periods of time then it needs to find a few good caves. That's the cheapest (i.e. cost-free) way of getting the protection you need. The thing is to find the caves and that's what rovers are for.

To misquote Genesis: from the cave you emerged and to the cave you will return.

I would think there are better ways using ground penetrating radar satellites of finding caves than driving rovers around.

But I would be unsurprised if Mars' lack of recent volcanic activity and four billion years of sandstorms has filled, buried or collapsed the sort of lava tubes that are the only real way of a having a cave in a place with no flowing water.

 

[Vertigo]

Except of course that all the indications are that it did have flowing water and for quite a long time.

Another approach is to go into some of the canyons which will limit the exposure to immediately above you.

 

[BAYLOR]

Except of course that all the indications are that it did have flowing water and for quite a long time.

Another approach is to go into some of the canyons which will limit the exposure to immediately above you.

Oceans. lakes and rivers . Lost about 2 Billion years ago.

 

[Onyx]

Except of course that all the indications are that it did have flowing water and for quite a long time.

Another approach is to go into some of the canyons which will limit the exposure to immediately above you.

Mars had a huge ocean at one time. But I had thought that there hasn't been significant running water near the surface for over a very long time, while their had been forces that destroy or bury caves during the same period.

When was the last heavy flowing water on Mars?


My overwhelming impression of Mars is a place that has its surface shaped by the movement of sand over a very long period. I wouldn't expect to find any particularly concave feature that hasn't been either filled it or worn down, including steep sided canyons. Caves and canyons are formed by things like fast moving water, earthquakes and lava. Mars is mostly wind erosion and the slow flow of sand, brine and dry ice.

 

[Onyx]

Looks like I was wrong about the Galactic Cosmic Rays on Mars:

"From MSL RAD measurements, ionizing radiation from galactic cosmic rays (GCRs) at Mars is so low as to be negligible. Intermittent solar proton events (SPEs) can increase the atmospheric ionization down to ground level and increase the total dose, but these events are sporadic and last at most a few (2–5) days. These facts are not used to distinguish Special Regions on Mars." (A "Special Region" is a region where Earth life could potentially survive.)

Water on Mars - Wikipedia

I don't know what the mechanism is, but maybe there is just enough atmosphere to make a difference, making SCR protection more important.

 

[Robert Zwilling]

I never thought about the irony of going back to cave dwelling while utilizing the latest technology to stay alive. Spraying foam insulation inside an existing cave seems like a pretty low tech way of creating a large living space. The main things to bring would be prefabricated doors, equipment to maintain and recycle the enclosed environment, and a good entertainment theater. That would make people think settling on the Moon wouldn't seem too difficult.

 

[Justin Swanton]

Looks like I was wrong about the Galactic Cosmic Rays on Mars:.

The amount of Cosmic radiation that reaches the Martian surfaces varies quite a bit but on average it is 300 mSv a day, the equivalent of 24 CAT scans. Of a crowd of people subjected to a little over ten times this amount of radiation - the amount absorbed in less than two weeks - half will die in 60 days. Mark Watney did not have a snowball's chance of surviving on Mars. Neither did the rest of the crew come to think of it.

 

[Brian G Turner]

In the Discovery Channel's series How the Universe Works they mentioned using existing lava tubes on Mars as a possibility for habitation, to escape dangerous radiation.

 

[Onyx]

The amount of Cosmic radiation that reaches the Martian surfaces varies quite a bit but on average it is 300 mSv a day, the equivalent of 24 CAT scans. Of a crowd of people subjected to a little over ten times this amount of radiation - the amount absorbed in less than two weeks - half will die in 60 days. Mark Watney did not have a snowball's chance of surviving on Mars. Neither did the rest of the crew come to think of it.

Is that GCR specifically or the sum of GCR and SCR? If it is mainly from SCR than the lagrange magnetic shield could work.

 

[Onyx]

In the Discovery Channel's series How the Universe Works they mentioned using existing lava tubes on Mars as a possibility for habitation, to escape dangerous radiation.

Did they make it sound like these tubes are empty and open to the surface where a lightly equipped ship's crew could get at them? Or were they talking about a large effort using excavating machines to bore down to them or clean them out?

I'm sure all sorts of geological formations might be present on Mars, I just doubt many are easily accessible from the surface because of the amount of time the surface has been eroding.

 

[Robert Zwilling]

Looked up lunar lava tubes. Article in Space, based on Lunar Reconnaissance Orbiter images in Jan, used the SETI Institute interpretation that says the lava tubes might be filled with frozen water and come right up to the surface. The article talked about leaving the water in the lava tubes as storage containers for ice. On Mars, it said the lava tubes could provide a warmer and wetter environment to live in.

Article in Smithsonian Air and Space said LOR images wrong kind of geology for lava tubes in the Philolaus crater. Seemed like they were saying there wouldn't lava tubes in any craters. Any ice exposed ice deposits would be small pits, a few meters in diameter. They were of the impression that hauling a nuclear reactor to the Moon would be the best bet for a suitable power source at locations away from the poles. However, they also said a suitable nuclear reactor would not be built for several decades. Their recommendation was to erect simple shelters at the bottom of polar craters and bury them with moon rubble. There would be plenty of easily accessible water and solar energy at the poles.

 

[Onyx]

There would be plenty of easily accessible water and solar energy at the poles.

They could also put the solar satellites in orbit using microwave downlinks for when the surface is in darkness. But there's no strong reason not to settlements at the poles.

 

[Danny McG]

I dunno why there's so much fuss over a liddle pool of water, everybody knows Mars has got canals full of the stuff

 

[Justin Swanton]

How much would it cost to set up a permanent moonbase? Optimistic estimates put it at US$40 billion or less but I don't buy that. A good yardstick is the ISS. It cost US$150 billion to construct and costs a little under US$3 billion a year to maintain, which includes getting crews to and from it. It will probably be necessary to double or triple those figures for the moon:

1. All lunar structures will need adequate shielding from Solar and Cosmic radiation. To build a shelter using lunar regolith or convert a cave will require fairly hefty construction machinery - you can't do it with a robotic trowel - and everything for the moonbase has to be landed by rocket power on the moon, not just boosted into LEO from Earth.

2. Crewing the moonbase will be much more expensive than the ISS as you have to get the crews to the moon, land them on the moon, and get them off the moon when it's time to go home. That's all additional rocket power, more weight, more cost to get into space.

3. Supplying the lunar base will be more expensive than the ISS for the same reasons.

Let's say a conservative US$300 billion to set up a base that can house as many crew as the ISS - 6 astronauts tops - and US$6-10 billion p/a to maintain it. $300 billion is nearly 10% of the US annual Federal budget. Does the United States have the political will to pay this tab?

 

[BAYLOR]

How much would it cost to set up a permanent moonbase? Optimistic estimates put it at US$40 billion or less but I don't buy that. A good yardstick is the ISS. It cost US$150 billion to construct and costs a little under US$3 billion a year to maintain, which includes getting crews to and from it. It will probably be necessary to double or triple those figures for the moon:

1. All lunar structures will need adequate shielding from Solar and Cosmic radiation. To build a shelter using lunar regolith or convert a cave will require fairly hefty construction machinery - you can't do it with a robotic trowel - and everything for the moonbase has to be landed by rocket power on the moon, not just boosted into LEO from Earth.

2. Crewing the moonbase will be much more expensive than the ISS as you have to get the crews to the moon, land them on the moon, and get them off the moon when it's time to go home. That's all additional rocket power, more weight, more cost to get into space.

3. Supplying the lunar base will be more expensive than the ISS for the same reasons.

Let's say a conservative US$300 billion to set up the base that can house as many crew as the ISS - 6 astronauts tops - and US$6-10 billion p/a to maintain it. $300 billion is nearly 10% of the US annual Federal budget. Does the United States have the political will to pay this tab?

All of which is a good argument for international cooperation and funding for such a venturer.

 

[Onyx]

To build a shelter using lunar regolith or convert a cave will require fairly hefty construction machinery - you can't do it with a robotic trowel - and everything for the moonbase has to be landed by rocket power on the moon, not just boosted into LEO from Earth.

How much conversion does a lunar lava tube require? Some go right to the surface, and the moon doesn't have sandstorms. It seems like that requires some ramps/ladders and a tent.

With more space, some gravity and much better radiation protection, crews could volunteer to stay for years at a time.

And a mass driver could also be used to land supply ships, so you don't necessarily need rocket propellant to land.

 

[Brian G Turner]

How much conversion does a lunar lava tube require?

Once you get Health & Safety and government lawyers involved? I'd say a lot.

Some go right to the surface, and the moon doesn't have sandstorms. It seems like that requires some ramps/ladders and a tent.

I presume you're not seriously suggesting the next Moonbase would be little more than a few tents?

With more space, some gravity and much better radiation protection, crews could volunteer to stay for years at a time.

In other words - if the Moon wasn't anything like the Moon and more like Earth?

And a mass driver could also be used to land supply ships, so you don't necessarily need rocket propellant to land.

You're going to need something to control any landing, though. I'm curious, though - do you see mass drivers as replacing launch vehicles to the ISS?