The Lick-Carnegie collaboration used over 11 years of continuous radial velocity measurement of the star Gliese 581, a nearby red dwarf star with about 30% of the mass of the sun (type M3V for you astronomers out there) that is already known to have two other small planets right on the inner and outer edges of the star's habitable zone - effectively jumbo-sized versions of Venus and Mars. Gg, however is right smack dab in the middle of the habitable zone with an estimated average surface temperature of 228 K - chilly but not "lifeless chunk of ice" cold. Also helping things out is the fact that planetary evolution models indicate that Gg is probably tidally locked to its sun, meaning that one side is in eternal day and the other in eternal night. This might allow the planet to have a wide range of temperatures - from scorching hot at eternal noon to extremely cold at eternal midnight. Gg is also about 30% more massive than the earth, meaning it's gravity is probably something like 10% stronger than ours, which might be helpful in holding on to an atmosphere.
So when do we send tourists? Probably not for a very long time. Gliese 581 is about 20 light-years away and our current fastest moving spacecraft (Voyager 2) is only going about 0.001% of the speed of light, so it'll be a very long time before we get a probe there to check it out, much less a person to write a travel review. And it gets worse. Since Gg's orbit doesn't happen to line up with our line of sight its sun, we can't even use satellites like CoRoT or Kepler to watch Gg transit across its sun. It looks like more information on Gg is going to have to wait for the next generations of missions like SIM-lite or New World Explorer which should be able to directly image it.
Very interesting Nick. It's only matter of time before we find life outside of earth. I will be excited for that day for sure.
ReplyDeleteIf it's orbiting a red dwarf, doesn't that mean the host star has already shed some outer layers?
ReplyDeleteSolar sails, fission or fusion, possibly antimatter drives should propel us to the stars someday....then there's always the slight possibility of reverse engineering whatever the heck these things are or Whiteman AFB UFO 1984 or ....
ReplyDeleteStan,
ReplyDeleteWhite dwarfs are stars that have shed their outer layers. Red dwarfs are very small main-sequence stars. The names are somewhat poorly defined, however, which is why we like to use very catchy codes like M3V to describe stars. Gliese 581 is about 8 billion years old but since it is burning its nuclear fuel so slowly it will live for another 190 billion years or so before it moves off the main sequence.
Quantum_Flux,
ReplyDeleteWe'll certainly need something better than what we have right now - 0.00001 times the speed of light isn't going to cut it for traveling to other stars.
My personal preference is for warp drives. :)
So if it is tidally locked, then how does the atmosphere work? Part of what makes our atmosphere work the way it does is that we are rotating and we have a slight tilt, which gives us our seasonal variations. What this means is that our atmosphere mixes fairly well with the air in the cold polar regions exchanging with the air in the warm tropical regions. So my question is, is there the same exchange of atmosphere between the warm and cold sides? If there is no rotation would that mean that the atmosphere mixing would have nothing to drive it. Would that mean that the "day" side has hot stagnate air while the "night" side has a frozen out atmosphere. I wonder if anyone has tried to model this type of planet to see how an atmosphere would behave. If I had access to an atmosphere modeling code I would probably look into it in my spare time.
ReplyDeleteSuggestions as to where I can find a good atmosphere modeling code?
ReplyDeleteNick Nelson,
ReplyDeleteThere is a lot more that we don't know about the nature of the universe than we do know. Our current models of gravitation with dark matter and dark energy don't necessarily seem to explain everything satisfactorily, and as far as assuming that the local constants are universally constant, etc. However, one plausible theory that I've heard in regard to the observed flying saucers is that they are highly advanced robots that replicate themselves throughout the universe everywhere they go, like a good and moral version of Berzerkers.
aka Self Replicating Spacecraft
ReplyDeleteI'm sure convection would mix the atmosphere at least to a certain degree. Certainly having one side constantly facing the star would provide very different selection criteria for evolution.
ReplyDeleteI'm curious about what kind of life would evolve under redish light. What sort of vision, camouflage might those creatures have?
QuantumLeap,
ReplyDeleteThere has already been some work on this - I couldn't find a more recent reference but I know this paper by Joshi, Haberle, & Reynolds gave the problem its first whack. They found that you get strong circulations between the day and night side, however they also found that for an earth-like atmosphere the night side temperature would be low enough to freeze CO2 out of the atmosphere, causing what they term "atmospheric collapse", which sounds unpleasant.
Quantum_Flux,
ReplyDeleteOne of the pressing questions about life elsewhere in the universe is the one posed by Enrico Fermi - "Where is everyone?" If you assume that intelligent life exists elsewhere in the galaxy, that advanced civilizations last for at least several thousand years on average, and that they are at least as curious as we are, then you have to wonder why they aren't already here. If we are an average bunch and we'll be out exploring the galaxy in a couple hundred years at most, we should be able to effectively explore the galaxy - even without warp drives - is a million years tops, especially if we start colonizing other planets. So really the question is "where is everyone?"
Stan,
ReplyDeleteI don't know what life would look like on 1.3 earth-mass planet around a 0.3 solar-mass star, but many plants here on earth already use a red version of chlorophyll that is more effective in collecting red and near-IR light, which would be what you get around a red dwarf.
Presumeably they would be in space. I think it is quite possible that self replicating spaceships ARE all over the universe, however they likely limit their spacial density throughout. It is probably pretty tough to distinguish a 50 foot radial disk from a NEO space rock, for instance, unless you examine it up close, especially if it isn't emitting analogue radio signals or doing any crazy manuevers. And even if there were an anomoly like a "space rock doing crazy manuevers", who is to say it isn't just another unidentified flying object that ought to be kept secret for reasons of national security?
ReplyDeleteDaedalus is the fastest plan we have right now. However it depends on some breakthroughs in ICF fusion that haven't happened. (And, I suspect, probably won't happen) However I think Daedalus could with current designs get there in about 500 years. Have some more fusion breakthroughs and you might make it in the lifetime of a person.
ReplyDeleteHoly cow!
ReplyDelete