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The article's second page answers this: Scientists go to all this trouble for the purpose of “planetary protection”—which usually means protecting other planet
by vor_ 13y ago
The article's second page answers this:
Scientists go to all this trouble for the purpose of “planetary protection”—which usually means protecting other planets from contamination by microbes originating on Earth. Most spacefaring countries have agreed to follow guidelines from the International Council for Science’s Committee on Space Research to reduce the chances of their vehicles carrying Earth organisms to other planets. The clean room procedures also safeguard against scientists mistaking Earthly microbes as extraterrestrial in origin if they are discovered on another planet, having caught a ride with a man-made spacecraft. “The whole idea of collecting information about what kind of bugs we have in the spacecraft assembly facility is to have baseline information so that in the future, if you find it on Mars, you have some grounds to rule out the possibility that it came from Mars,” Vaishampayan says.
- dekhn 13y ago120kg of matter is exchanged between Mars and Earth per year, already. They've just reduced the possibility of contamination by their spacecraft, compared to natural events.
- Crito 13y agoBeing able to make the distinction between panspermia induced by human activity, and panspermia that occurred through some other mechanism is important. The possibility that life jumped the gap on meteorite strike debris does not make protecting against contamination any less important. Actually, I would say that it makes it more important. If there was no possibility for non-human related panspermia, then if we found an organism on Mars that appears closely related to an earth organism, then we could write it off as contamination and ignore it. However since non-human related panspermia could conceivably happen, it would be more difficult to pin such a discovery on contamination.
- Groxx 13y agoCitation please (sounds interesting, but yeah), and does it get exchanged at the speed that this stuff does, or does it take thousands^x years to arrive? Not that I disagree. Just wondering if there are a few orders of magnitude that need to be considered.
- raverbashing 13y agoWell, it's much, much easier to have stuff from Mars to Earth than the other way round, because of the following reasons: 1 - Less gravity on Mars -> smaller escape velocity 2 - Mars is in a higher energy level (gravity wise w.r.t the Sun), so Mars to Earth is "falling down", but you need energy to go from Earth to Mars
- Groxx 13y ago1) agreed. there's solid evidence that Mars sends junk to us - not sure about the other way around. 2) does that matter, since they're in orbit, thus zero/microgravity? You still need energy to leave an orbit, whether up or down, I don't see how it makes a difference. There's no friction to speak of to make "down" a direction that things are predisposed to move in. Over ridiculous time scales sure, but ridiculous time scales are nothing like human time scales, so we still have many orders of magnitude difference if we fling stuff at Mars intentionally.
- dhimes 13y agoYes it matters- the Sun is the main provider of gravity for this consideration.
- Groxx 13y agoorbit. gravity is canceled out by orbital velocity, as far as distance-from-sun is concerned. it costs Mars nothing to stay in orbit, and to go down to a -100m/s orbit or up to a +100m/s orbit costs the same amount of energy: (mass of mars) * (100m/s velocity change) if Mars and the Earth were not orbiting, I would completely agree. drop something from Mars and it'll land on Earth, and the reverse is not true. but they're not - drop something on Mars and it's just in Mars' orbit.
- mikeash 13y agoDelta-v requirements for transfers in space are generally symmetrical. It takes the same amount of delta-v to go from Earth's orbit to Mars's orbit, for example, regardless of direction. The one thing that changes this equation is aerobraking (or, when dealing with stuff whose structural integrity isn't important, lithobraking). Because drag works in one direction, that means that you can take advantage of it when arriving but not departing. For that reason, for example, it takes more delta-v to reach a transfer orbit to Mars from Earth than it takes to reach Earth from a transfer orbit to Mars. Technically that's not true, but when arriving at Earth, a great deal of delta-v can be provided by the atmosphere or the ground.
- dsjoerg 13y agoReally? Can you explain or give a source?
- dekhn 13y agoBTW, I found the source of this quote- it's from Craig Venter (he cites it as a reason for sending his DNA sequencer to Mars). I can't find anything supporting his statement, however.
- andyjohnson0 13y agoMy question was about Herschel, for which planetary protection is irrelevant because its not visiting any planets.
- hnriot 13y agonot to mention that being constantly irradiated in space will kill practically everything.