How long do you all think it will be before life is discovered on one of them?

Please read: http://www.space.com/scienceastronomy/050509_exoplanet_review.html

Im quite surprised actually they havent found out 100% with all these high power telescopes they have now.. I can almost guarantee there is other life in the vast space of "space"...

How long do you all think it will be before life is discovered on one of them?


"I don't know".

Which is kinda the most interesting answer a science geek can have, but it's also the most frustrating.


Im quite surprised actually they havent found out 100% with all these high power telescopes they have now.. I can almost guarantee there is other life in the vast space of "space"...


We've yet to really image one of these things.  Most of them, all we're doing is looking at the central star and seeing if it's wobbling back and forth periodically.  That's why we tend to find huge planets with short orbital periods, aka "Hot Jupiters", because they're the kinds of planets that will make their central stars wobble more than "normal" planets, and the wobbling is fast enough that we can see it after a few months of observation, rather than a few years (or decades) of observation that it would take to detect smaller planets at longer range.  Problem is, these planets kinda suck for life.  1000+ degree temperatures on the cold side of the planet, and no surface, just a crushing inferno of gas.

We've gotten what we think might be a spectral signature of the atmosphere of one or two of these worlds, but these are really at the limit of our present ability to detect. (The planet has to be orbiting in the "right" way relative to its star, which is pure luck...)

The atmosphere is worth measuring because it's a hint towards whether or not a world contains life.  Oxygen, in particular, is a nasty and corrosive gas.  It reacts with anything it comes into contact with.  Over any geological time scale, it won't be found in appreciable quantities in any atmosphere unless there's something on the universe that's generating it.  It's so nasty and reactive, however, that the processes that generate it require considerable energy input.  A planet with oxygen in its atmosphere is like a fireplace in which you throw charcoal and end up with wood; it doesn't make sense unless there's something actively taking energy input from the sun and using it to drive the sorts of chemical reactions that turn relatively inert chemicals like CO2 into the wildly active O2.

If someone finds a planet whose atmosphere contains a disproportionate amount of oxygen (specifically diatomic oxygen, water, and ozone), I'd accept that as very strong evidence for extraterrestrial life, and certainly worthy of further investigation.

The Terrestrial Planet Finder was supposed to give us the ability to answer these sorts of questions; it was designed to have sufficient resolution to examine the atmospheric spectra of Earth-sized rocky planets.  Unfortunately, the program's in funding limbo at the moment.

If, after TPF or DARWIN (or their future equivalents) have looked at 1000 stars and finds no biosignatures, we can conclude that life is pretty rare.  If they looks at 1,000,000 stars and still find nothing, we can conclude that life is extremely rare, and that we may be unique in the galaxy.

Present funding debates aside, barring planetary economic collapse, some mission of this sort will likely be launched by some spacefaring nation before 2020. 

So if you're reading this in 2008, and your life expectancy extends anywhere past 2050, you'll probably live to have an aswer better than "I don't know" in your lifetime.  I'm willing to bet we'll have two hypotheses:

A) A TPF-like mission found an oxygen/water/ozone biosignature around a world orbiting some random star.  A successor mission launched in 2050, designed to image this world around this star, found that the planet's surface was about the right color (in the case of Sol and Earth, "green" chlorophyll is a good way to do photosynthesis from a "yellow" sun) of a chemical that could be used to drive photosynthesis from whatever color the star happened to be.  Life is almost conclusively confirmed.  We learn a lot about how life works, because for the first time in 3 billion years, we have something to compare ourselves against.

B) A TPF-like mission found many small rocky worlds orbiting many stars, but they all had atmospheres consistent with non-biological origins.  Mark a "we have no idea, but probably no life here" on all of these worlds, and the search for life continues.

I'm hoping for A), but betting on B).  But even "B" is useful information.  In the first year or two, we'll probably look at 100 lifeless rocks.  Finding nothing means life is rare, but still worth looking for. 

If we've found nothing by the time we've launched a couple of successor missions capable of looking further out, and upped those numbers to 10K-100K stars, the odds are the we're the only living things within 10,000 light years, and the only sentient lifeforms in the galaxy.  I'd give 50/50 odds that if I die of old age, I'll have sound evidence to believe either that there exists extraterrestrial plant life, or conversely, that we're the probably the only sentient beings in the galaxy, and what a waste of space it would be if we rendered ourselves extinct before colonizing it.

Both outcomes are fascinating.