New Mars Forums

No comments, just some info. We'll see what happens. maybe it's just a talk.

Japan, Russia discuss joint Mars mission

Thanks all for posting. I guess, the research of low G impact on human health and ways to reduce it should be of high priority. It will determine the way we go in space exploration and settlement. I don't think we will be settling gas giants (thanks Karov, it sounds interesting but I just can't get my head around this possibility ). I like your optimism, though. Things are done by optimists. In my opinion we can settle only on solid planets/moons.

If we are limited to the minimum of 30% Earth G - we have only Venus, Mars and Mercury to work with. Settlements somewhere else will only be possible if we get enough artificial gravity machines or come up with the method to counter the impact. The lowest limit of about 10% of Earth gravity would give us the Moon, Ganymede, Callisto, Europa, Io and Titan - not bad. On these moons even heavy suits and boots could work for extra exercise. I imagine the gravity machines could be quite big and expensive.

Should we go about terraforming small moons if we know that people who settle there would have it hard to return to Earth? They would have new plant and animal species adjusted to the low gravity. I mean, we could get a new human race raised on the Luna type of moons who feel quite comfortable where they are. Do you think, it's inhumane? Everyone would be aware of the risks, so it's a free choice. What's your opinion on this?

As for people going to low gravity objects for work - a research would explain how long people can live on a particular body. A record stay in 0 G was over a year - the Russian cosmonaut who did it required some adaptation back on Earth but recovered well. Low G is better than 0 G and enhanced with vitamins and exercise would mean a permissable stay on a Luna type object could reach 5-10 years - sufficient time if we want to go Jupiter's and Saturn's moons - where a short stay wouldn't make sense.

Let's not say what is possible and what is not until it's proven. I'm eager to see how the experiments with animals in low gravity will go.

Karov, could you give me a link describing the test with rats, you were talking about?

Most solid planets/moons have gravity lower than Earth, which will put off people from settling permanently on smaller bodies. This includes Mars with its 3.71 m/s2 surface gravity and the Moon with 1.62 m/s2. The smaller the body, the more danger to health. Well, if somebody decides to settle permanently on a moon, they will feel comfortably there but coming back to Earth might be a problem. Is there anything we can do about it with the current knowledge of medicine? Or, does anybody know about the research results? I've heard about about experiments with mice (exposed to low and 0 G) but don't know what happened.

Planet/Satellite Name Surface Area (square km) Observed surface gravity (m/s2)
Mercury 74,815,144 3.7
Venus 460,234,317 8.87
Earth 511,209,977 9.81
Moon 37,958,532 1.62
Mars 145,011,003 3.71
Io 41,396,452 1.79
Europa 30,935,401 1.31
Ganymede 86,986,441 1.42
Callisto 72,382,295 1.23
Titan 83,322,891 1.36
Titania 7,822,830 0.372
Oberon 7,277,449 0.346
Triton 22,902,210 0.783
Pluto 16,245,414 0.651
Charon 4,315,241 0.334

Here are some FAQ about gravity (and other health hazards) answered by an astrobiologist. Exercise is the only method used so far.
http://weboflife.ksc.nasa.gov/faq.htm]Ask the astrobiologist

Thanks, Gennaro. I don't want to discuss the Moon vs Mars issue. A lot of people have done this already. And Mars is my preferred first candidate for settling/terraforming too for various reasons. Nevertheless, the Earth's Moon will be candidate number 2 for most people, not Venus, Mercury, Callisto or Ganymede (some will disagree but the majority of terraforming enthusiasts will agree) and should not neglect it. That's why I started this discussion. Bringing volatiles to the Moon - gases and water would be easier than cleaning excess atmosphere on Venus (possible but much more work required), Mercury has its own big problems, probably not terraformable in the pure sense, the Jovian moons are too far away and G is even lower than on the Moon. Whatever you say, Mars and the Moon will always be the frontrunners in settlement. Of course, it's a problem for people deciding to stay on a low G body, if they can't move around easily but medicine may get get some answers to this problem, hopefully.

I agree we need to investigate and know all consequences, more research should be done on long exposure to low G. Vitamins and lots of exercise would be the answer for temporary visits - even few year contracts are possible (the lower the G, the shorter contracts could be).

It's going to be some time before anyone will have a chance decides to settle on another planet/moon. It's hard to predict how good the environments could get. Obviously, no-one is going to rush to a desert planet.

Hi Shaun,

In my opinion we should terraform/paraterraform bodies with the lower gravity too. Even if we end up with the worlds full of plants and animals, with no humans, it is worth doing it for preservation of species and expansion of life forms. However, the planets/moons with the lower gravity will be populated anyway, temporarily or permanently. By the time the Moon is terraformed we will know the exact effect of the lower G on the human body. People will still want to settle the Moon to make it their home, even if they or their kids will never be able to visit Earth. We don't know what technology could be used in the future to allow just that if necessary. Lunarians (Lunites?) might want to adapt to Martian G first, before visiting Earth.

Bodies like the Moon are more common in the Solar system and more probability that find a lot of Luna-sized bodies elsewhere than Terra-like bodies. Even smaller bodies like Titania or Triton will be even more common. Native Tritonians will have trouble even visiting the Earth's Moon! The trouble starts when not only large planets/moons are colonized but smaller moons (Saturn's Rhea, Uranus's Umbriel, Miranda) and large asteroids - Ceres, etc.

The larger bodies should be settled first, taking into account the terraformability and the efforts required, e.g. Mars before Venus, then Mercury or the Jovian moons (Callisto and Ganymede first).

Groups of planets with similar gravity (only the largest):
Earth-Venus
Mars-Mercury
Luna-Ganymede-Callisto-Titan-Io-Europa
Titania-Oberon-Triton-Pluto-Charon

As you can see, Mercurians will be comfortable with the Martian G, Lunar people with the G of the 4 moons.

Planets/Moons and the surface gravity in descending order - not 100% accurate but pretty close (better viewed in MS Excel)
Planet/Satellite Name    Observed surface gravity (m/s2)
Earth    9.81
Venus    8.87
Mercury    3.9
Mars    3.8
Io    1.79
Moon    1.62
Ganymede    1.42
Titan    1.36
Europa    1.31
Callisto    1.23
Triton    0.783
Pluto    0.651
Titania    0.372
Oberon    0.346
Charon    0.334

I know there's going to be some experiments on mice/rats - on how they can handle 0 or lower G's and if their offspring can survive back on Earth. I'm interested to know about this development.

No need to do this for a few billion years, I guess :sleep:

Some more data on planets/moons

Planet/Satellite Name    Surface Area (square km)    Observed surface gravity (m/s2)
Mercury    74,815,144    3.7
Venus    460,234,317    8.87
Earth            511,209,977    9.81
Moon            37,958,532            1.62
Mars            145,011,003    3.71
Io            41,396,452    1.79
Europa    30,935,401    1.31
Ganymede    86,986,441    1.42
Callisto    72,382,295    1.23
Titan            83,322,891    1.36
Titania    7,822,830    0.372
Oberon    7,277,449    0.346
Triton            22,902,210    0.783
Pluto            16,245,414    0.651
Charon    4,315,241    0.334

http://www.cnn.com/2004/TECH/space/06/2 … html]Space Elevator

Is this a good idea? In K.S. Robinson's Mars trilogy the first space elevator ended up in a disaster. We don't want it to drop on Earth. I am not against the idea itself, though.

This link is not working.

Of course, it's all theoretical - people have other priorities - Iraq, etc. There was no human on the Moon in 30 years, nobody is interested in colonizing/ terraforming.

I am not convinced that the atmosphere will disappear soon, I tend to believe the optimistic estimates (Have you read the link I gave in Mercury thread). Some estimate the Moon to hold the atmosphere for thousands, some for millions and some indefinitely. We won't know for sure. Massive atmospheres are different from a glass water in your example because of it mass and the way the atmosphere works - the upper areas reflect some light. I am not even sure that water from that glass will go into space, maybe it will be soaked by sand instead. The lost atmosphere can be topped up gradually.

As for bringing atmosphere to Luna - some people already posted about rediverting the asteroids - cheap and easy, at least, it's easier than shipping volatiles from other planets.

The ingredients of the atmosphere are important too. Nitrogen is pretty heavy. (Titan has less surface gravity than the Moon but has a very thick atmosphere). Water vapour will create clouds and reflect light. Extra frozen water will stay around the poles.

I think what India does is great. Should a country become rich before they can do something big? Maybe it's their way of getting there. Somehow, I think some day space exploration and all related industries (it's actually ALL industries - starting from agriculture to high tech) will boom again when people start making some money out of space.

If settlement of Mars starts, it will never stop (and continue to other planets)! They will want all the infrastructure and environment we have on Earth, including education, health and entertainment, then we will want better ships, both natural and technical scientists will be in high demand. Mars will offer better wages, once transportation costs drop. Brain wash on Earth will cause improvement of conditions on Earth - it's just a demand and offer arithmetics. :laugh:

BTW, I am not naive, I just believe that's going to happen. I don't believe much in Nostradamus but didn't he predict a millennium of complete prosperity and peace?
...
China was very poor a couple of decades ago, now it's not so bad thanks to innovations and good management of the economy.

Thank you,

I have sent an invitation to this forum to Paul Birch a few days ago (a "Quick Terraform Specialist" ). Not sure if his email address is still active.

Another terrafoming advocate is Gerald Nordley:

http://www.sfwa.org/members/Nordley/]ht … s/Nordley/

He wrote an interesting article about terraforming small planets/moons:

http://www.sfwa.org/members/Nordley/Gra … ravity.pdf

I have just sent him a note.

EDIT:

Here's his answer:

Mercury has already some magnetosphere but it needs to be enhanced.