What's the largest difference between the International Space Station and a manned lunar base?

Wednesday, September 30, 2009

In making the pitch for a permanent manned presence on the Moon it's good to keep a few things in mind on how a base on the Moon would differ from the only base we have at the moment in space.

The largest difference would probably be that of permanence. The ISS is always in a bit of a precarious state, as it circles the Earth in an orbit of continual decay, meaning that every once in a while a ship sent up to the station will need to boost it into a higher orbit in order that it not sink too low and eventually enter the Earth's atmosphere. There are even some tentative plans to de-orbit the space station in 2016 (!), just a few years after completion. That would be extremely bizarre, but that's what can happen when funding is short.

Leaving the subject of the fate of the ISS alone for a second, let's compare it with a base on the Moon. The Moon not only has a solid surface but it also has no atmosphere, meaning that a footprint made on its surface will stay there almost forever, unless something happens to impact it or an area nearby. This means that anything we build on the Moon will also be permanent. Even before manned missions are sent to the surface it should be possible to send robots over to do some basic construction on their own. One example might be the creation of a simple landing platform, since a great deal of moon dust gets kicked up when a rocket lands. Once we have a landing pad, it will remain there forever and become a permanent part of the usable infrastructure.

This applies to any type of infrastructure built by either robots or humans, so even if a manned mission were to only exist for a year or so and then have to return to Earth due to a lack of crisis we would still have all the infrastructure on the surface waiting for us to return. Habitats (probably tucked into the side of a hill to avoid micrometeorite impacts and radiation), rovers, paths/roads, signs, you name it. So it's good to remember that any money spent on colonization of the Moon would not simply be a project but also a future investment, even in the worst possible situation where funding is cut off and the mission is cut short.


Another big difference will be finding out for the first time how low gravity affects human physiology, as opposed to 0g. We have not yet had any long-term experience with this. Life on a settlement on the Moon would be vastly different from that on the ISS due to this. On the ISS astronauts sleep by tethering a sleeping bag to the wall, then curling up in that and falling asleep while floating. They can't take showers, food and drinks has to be consumed with care, objects are always floating around and becoming lost, and most importantly, special exercise stations have to be set up to work the body enough to avoid the long-term effects of zero g. On the Moon sleeping would be done on beds/the floor as on Earth, eating would be done normally, showers technically could work (but they would be a waste of water so they would probably use sponges instead), and exercise would be a much simpler task to carry out. Technically, astronauts on the Moon could exercise simply by setting up a few tools that could probably be manufactured on the surface as well: a chin-up bar, weights to hold overhead while doing squats, weights to hold on one's chest while doing sit-ups, etc.

The psychological difference in being located on a solid surface will also be interesting to note. The ISS is quite huge, but once you've reached the end of it there's no going past that point, and the only way to expand on it is by adding new sections. On the Moon an astronaut feeling a bit stressed could technically just suit up and go for a drive. Actually, depending on the type of vehicle it would be possible to drive without even suiting up, if the interior happens to be pressurized. Not recommended in the beginning, but it would technically be a possibility.


Two more links on the subject of water on the Moon worth reading are here and here. The first is by the CEO of the X Prize Foundation, on the significance of the discovery itself and the subject of private sector involvement. The second is on the water itself and has two important points to remember: the "top two millimetres" where the water has been found simply means the location that has been measured, and does not mean that water only exists in this area. The second point is that since the water is driven away from the soil somewhat during the day when the temperature rises past 100 degrees C, this implies that simply heating the soil up to a similar degree may be enough to extract the water from it.

The timing of this discovery couldn't have been any better, considering that LCROSS is embarking on a similar mission and is due to impact the Moon in just nine days. China just announced a 3D map of the Moon yesterday as well. Thanks to all this we can expect to see the subject of the Moon remain in a prominent position for at least the next two weeks.

4 comments:

Anonymous said...

Sellamat Dave !

Don't the astronauts have a special device to take a shower; i.e. this is a kind of huge tube where the water is in closed circuit, so that no drop gets lost ?

Olivier

데이빛 / Mithridates said...

They used to take showers on Skylab in the 70s, but the ISS is a much longer-term project so it's sponge baths for them. Even then a bit of water gets lost every time.

http://science.nasa.gov/headlines/y2000/ast02nov_1.htm

Anonymous said...

Yes, you must be right about Skylab. Indeed, when I was a kid, I had a book describing the life of astronauts, and there was much information about Skylab in it.

Olivier

데이빛 / Mithridates said...

They used to take showers on Skylab in the 70s, but the ISS is a much longer-term project so it's sponge baths for them. Even then a bit of water gets lost every time.

http://science.nasa.gov/headlines/y2000/ast02nov_1.htm

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