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The Moon doesn't buy us much... Water ice and He-3, sure, but that's about it. You can't swing a dead cat in the solar system without hitting a chunk of water i

The Moon doesn't buy us much... Water ice and He-3, sure, but that's about it. You can't swing a dead cat in the solar system without hitting a chunk of water ice and we are a long ways from needing substantial quantities of He-3. Mars makes a more sense for a lot of reasons. A self-sustaining outpost on Mars is a _lot_ more plausible than the Moon. Due to the availability of carbon, there are a lot of substances that are a lot easier to make on Mars (notably, rocket fuel). The Martian atmosphere is 100x less dense than Earth's, but it is 100000000x more dense than the Moon's. While ~0.01 atm isn't a lot of pressure, it's certainly enough to be useful. The Moon is closer, but really they're both firmly in "if something goes wrong, you'd better be able to fix it on your own" territory. It takes a bit more energy to get to Mars, but since you can use the atmosphere of Mars to slow down, the difference in energy requirements to get to the surface of each aren't vastly different. If ESA and CNSA want to head to the Moon, great, I think any progress in that direction is great, but I think Mars is a much better goal (and the Moon isn't really "on the way" to Mars).

rimliu 10y ago
> you can use the atmosphere of Mars to slow down Is that true? Because my understanding is that Mars have just enough atmosphere to cause troubles but not enough to help. Hence the tumbler design of smaller spacecraft landing on it and insanely complicated landing of Curiosity which is larger.
- ceejayoz 10y ago
  The Martian atmosphere is commonly used to aerobrake. If you can use parachutes in the Martian atmosphere (at least to some extent), you can sure as hell use it to slow a spacecraft. https://mars.nasa.gov/mro/mission/timeline/mtaerobraking/ https://mars.nasa.gov/mro/mission/timeline/mtaerobraking/ https://mars.jpl.nasa.gov/mgs/sci/aerobrake/SFMech.html https://mars.jpl.nasa.gov/mgs/sci/aerobrake/SFMech.html https://mars.nasa.gov/odyssey/mission/timeline/mtaerobraking/ https://mars.nasa.gov/odyssey/mission/timeline/mtaerobraking... etc. Curiosity's complex landing system had little to do with the atmosphere, and a lot more to do with a) not wanting to land the thing on a hillside or in a crater it couldn't get out of (which nearly happened to Opportunity - http://www.space.com/36587-mars-rover-opportunity-landing-site-new-photo.html http://www.space.com/36587-mars-rover-opportunity-landing-si...) and b) the much larger size than previous rovers, making airbag bouncing less suitable.
TheOtherHobbes 10y ago
The Moon works as a nice achievable MVP for a first iteration at colonisation tech. Mars is orders of magnitude harder and more likely to end in failure - which apart from the immediate fate of the victims, would also be a PR disaster that could set colonisation programs back by decades. There's a lot to be said for developing launch tech to explore/colonise/mine the rest of the solar system from the bottom of a shallow gravity well instead of a deep one.
- JshWright 10y ago
  In many ways, Mars is easier. Really the only way it's harder is that it's further away (so it takes more energy and travel time for stuff (both payload and communication signals) to get there). The Moon, on the other hand, lacks an atmosphere, has very little gravity, and is extremely resource poor, and has bigger temperature extremes. It presents a lot of challenges that don't exist on Mars (or are substantially reduced). If you want to build a base as a staging area for expeditions, there's no point in putting it on the surface of anything. Just stick it in the Earth-Moon L2 (rather than wasting a couple km/s getting down to the surface of the Moon and back).

rimliu 10y ago

> you can use the atmosphere of Mars to slow down Is that true? Because my understanding is that Mars have just enough atmosphere to cause troubles but not enough to help. Hence the tumbler design of smaller spacecraft landing on it and insanely complicated landing of Curiosity which is larger.

ceejayoz 10y ago
The Martian atmosphere is commonly used to aerobrake. If you can use parachutes in the Martian atmosphere (at least to some extent), you can sure as hell use it to slow a spacecraft. https://mars.nasa.gov/mro/mission/timeline/mtaerobraking/ https://mars.nasa.gov/mro/mission/timeline/mtaerobraking/ https://mars.jpl.nasa.gov/mgs/sci/aerobrake/SFMech.html https://mars.jpl.nasa.gov/mgs/sci/aerobrake/SFMech.html https://mars.nasa.gov/odyssey/mission/timeline/mtaerobraking/ https://mars.nasa.gov/odyssey/mission/timeline/mtaerobraking... etc. Curiosity's complex landing system had little to do with the atmosphere, and a lot more to do with a) not wanting to land the thing on a hillside or in a crater it couldn't get out of (which nearly happened to Opportunity - http://www.space.com/36587-mars-rover-opportunity-landing-site-new-photo.html http://www.space.com/36587-mars-rover-opportunity-landing-si...) and b) the much larger size than previous rovers, making airbag bouncing less suitable.

TheOtherHobbes 10y ago

The Moon works as a nice achievable MVP for a first iteration at colonisation tech. Mars is orders of magnitude harder and more likely to end in failure - which apart from the immediate fate of the victims, would also be a PR disaster that could set colonisation programs back by decades. There's a lot to be said for developing launch tech to explore/colonise/mine the rest of the solar system from the bottom of a shallow gravity well instead of a deep one.

JshWright 10y ago
In many ways, Mars is easier. Really the only way it's harder is that it's further away (so it takes more energy and travel time for stuff (both payload and communication signals) to get there). The Moon, on the other hand, lacks an atmosphere, has very little gravity, and is extremely resource poor, and has bigger temperature extremes. It presents a lot of challenges that don't exist on Mars (or are substantially reduced). If you want to build a base as a staging area for expeditions, there's no point in putting it on the surface of anything. Just stick it in the Earth-Moon L2 (rather than wasting a couple km/s getting down to the surface of the Moon and back).