About the search for life on other planets

Question

Ok, so I just read an article on CNN that discussed the discovery of some sort of toxic chemical in the soil on Mars. The article said that because of this chemical, scientists now doubt that life could exist on Mars.

Which made me think of something: who says life on other planets needs the same things humans need?

Who says aliens need water? Who says aliens need a certain temperature range? Who says aliens need this particular mix of gases, or this amount of sunlight, or anything else we assume? Why couldn't life exist on Venus? Obviously, if anything lives on Venus, it would be adapted to the extreme temperature, right?

I firmly believe in life on other planets, and it frustrates me that to my understanding, such conclusions have been made that all life needs Earth-like conditions.

Answer 1

Life does require water and a certain temperature range.  The range is rather larger than once believed since the discovery of extremeophile bacteria.  But this discovery does not negate the basic principle.  This is understood by every biologist.  

You "firmly bllieve in life on other planets"  Why.  You have no evidence whatsoever.  Firm belief in something without any evidence is foolish.  It is the opposite of science.  

In assuming life needs Earth-like conditions you are making a fundamental error albeit one that is rather common for people unfamiliar with the subject.   Any biologist can tell you that LIFE MAKES EARTH-LIKE CONDITIONS.  Not the other way around.  Early in Earths history the conditions were deadly.  Not at all what you might consider "earth-like"  Life developed and changed its environment.  Sometimes to its own near extinction.  

Answer 2

Unfortunately, i'm not able to find a CNN article on this topic.  Perhaps you could provide a link in an update.

We only have one example of life - that found on Earth.  It has a specific chemistry.  This chemistry has temperature ranges where it works, and so on.  However, the more we look for life on Earth in new places, the more life we find.  So life doesn't just survive, but thrives in geothermal vents in water considerably hotter than boiling, in highly acidic places, highly alkaline places, places with high salt content, deep underground where the temperatures and pressures are high, on the rocks in Antarctica, high in the atmosphere, and so on.  As time has gone on, main stream scientists have expanded their thinking on what is habitable.  This is fairly recent.

Life on Earth needs water, however.  The driest places on Earth have life.  But the driest places on Earth are very wet compared to most of the surface of Mars.

There is speculation that life could exist in the upper atmosphere of Venus.  In fact, we could probably live there.  There is an altitude where the pressures and temperatures are fairly reasonable.  We could live in floating cities.  We'd still have to generate oxygen, deal with a highly acid environment.

Water is very common.  Water has been detected on all of the planets in the solar system, and many of the moons.  There seem to be many places just in the solar system to look for life.

The Phoenix lander has a microscope that has sharp enough resolution to image common Earth bacteria.  Though finding life is not a mission goal, it seems possible that it could be found anyway.

It's unlikely that anything toxic to Earth life would sterilize a planet.  Oxygen was toxic when it was introduced to the Earth.

Answer 3

Scientists look at the vast numbers of life forms on the Earth and the fact that they all have the same commonallitys. They require Oxygen, are Carbon based, etc. As such we know what conditions are necessary for life but not for other forms so it is likely we would overlook evidence for supporting other chemically based lifeforms. Since NASA's budget is limited, it has to make best use of it's dollars by looking for something it has knowledge and experience with. By the way the the Perchlorate found by the Phoenix lander may be contamination from us. NASA is still doing research into this so it is important not read to much into their press releases.

Answer 4

I am sure that the scientists that commented meant life similar to us or basic life that we understand.

Many scientists have postulated that life could possibly be based on some element other than carbon. Silicon would be one possibility.

I think you took the response out of context.  

Answer 5

um.. lets see... all life that we know of... needs H20... so if can find it we know similar life could exist and if they don't why didn't we see millions of little green guys running around all over Mars?!? the thing about venus... lets say there is life there.... we will never know because the space probes we send to venus melt in about 2 hours after landing... wow... what a dumb question.

Answer 6

Nobody will ever talk you out of "Aliens", huh

They have something special in store for you very soon.

Google/youtube: "Project Bluebeam"

"Aliens" just in time for 2012! Many will be fooled...

Answer 7

You may have a good point, why assume any life may be earth-like, carbon based, water-based?

More and moe 'extreme' forms of life are being found on earth suddenly since the 1980's some of which were assumed impossible before that (submarine vents, high temperature life in geysers, bacteria in rock 1000's of feet below surface, etc.)  Some people have worked out broad schemes of life based on different basic elements replacing the elements used on earth and can (very roughly) show its plausibility.

But, there is a good reason for looking for carbon and water based life.

The fundamental materials are wide spread and many organic (carbon) molecules exist is space, including some fairly complex ones once thought to be life dependent.  Since they are so widespread it is a reasonable guess that life in other spots are likely to be formed from the same  chemicals and through vaguely similar processes.

But we should try to not overlook the other possibilities.