NASA's WISE telescope to launch next month (December 2009); press conference to be held on 17 November
Saturday, November 14, 2009
The reason why this is interesting is because we don't know if there are brown dwarf stars nearby. The general rule for bodies in space is that smaller ones are more plentiful than larger ones, which is why there are more stars like our own sun than there are giants, and more red dwarfs than their are stars like our sun. Go a bit smaller and cooler than this and we come to brown dwarfs, which are certainly more common than red dwarfs but are virtually invisible and thus nearly impossible to detect using visual methods alone. Thus, for all we know we could have a brown dwarf at a fairly close distance from us (1.5 light years or so, for example) and not even know about it. WISE will finally be able to confirm whether there is something there or not.
To illustrate that we have an interesting quote here: "These low mass stars are expected to be more numerous than the more massive stars like red dwarfs, and thus there should be brown dwarf stars closer to the Solar system than Proxima Centauri."
There is a theory that there is a star orbiting our Sun that brings about wide-scale extinctions every 26 million years or so, and the nickname for this star is Nemesis. WISE isn't specifically made to look for this proposed star, but it will be able to tell us once and for all whether this is true or not. Note that there could easily be a brown dwarf out there in between us and Proxima Centauri that has nothing to do with mass extinctions on Earth, so simply discovering one doesn't necessarily mean that it's the proposed Nemesis, but such a discovery would be no less exciting.
As for how long it would take to reach such an object, see Project Longshot (also here). This was a proposed mission to Alpha Centauri (4.3 LY away) that would take about 100 years to accomplish, plus of course the extra 4.3 years it would take for a signal to reach Earth. Added to this is the fact that it is more than likely that a probe sent off to study the system would be surpassed by observational technology back home, since developments in that field are extremely quick. In short, there is no real reason to send a probe at our current level of technology to an object that distant.
What about a brown dwarf star at 1.5 LY away though? Well, that's still 100,000 AU away, and the probe farthest from the Earth (Voyager 1) has gone a mere 111 AU all this time.
But then again, that's 1% of the distance without even trying. If one or more brown dwarf stars turn out to be located between us and Proxima Centauri thanks to WISE we may see a sudden flurry of proposed mission designs similar to Projects Daedalus and Longshot, except that this time we would be talking about a distance just barely possible within a few decades.
Well, enough speculation. The telescope will launch 7 December and thus we will know my July 2010. After that we will know whether there's anything out there worth speculating about or not.