http://www.universetoday.com/128416/ac-best-place-look-et/ How will they steer the craft? Space is not empty and over time, small corrections will be needed to stay on track. At only a few grammes there will be no space for thrusters and fuel to power them.
With the backing of such big name sponsors as Mark Zuckerberg and Stephen Hawking, his latest initiative (named “Project Starshot“) aims to send a tiny spacecraft to the Alpha Centauri system to search for planets and signs of life.
They may find little furry creatures…
Consisting of an ultra-light nanocraft and a lightsail, the concept calls for a ground-based laser array to push the lightsail up to speeds of hundreds of kilometers an hour...
They’ll need to go a little faster, though. If they want the craft to get even close before warp drive is invented.
At only a few grammes they could probably be steered using only a tiny amount of compressed gas. Over such vast distances even a teeny correction could make a fairly large impact on where it ends up. It’s likely that communication with the device is the greatest problem… it would take years for any course correction instructions to reach the craft. Basically it has to have very low mass, be extremely power frugal, yet almost entirely autonomous. That last one could defeat the first two. You’d need some impressively energy dense batteries to carry it through the interstellar medium, even with hardware that only sips electricity.
Luckily there have been many advances in making very small, highly efficient computer chips. I can offhand think of a couple of chips that are indeed extremely light on juice, can “sleep” for months on end with very little power draw, etc… You’d only need to “wake up” the computational hardware every N months or so … and then only for a few minutes at a time just to check your course or receive instructions. Timing the sending of said instructions could prove pivotal to making batteries last. Some people are going to be doing some fun math to do this. And if you miss the window you’ve only wasted a couple of years…
You’ve intrigued me now. At only a few grammes we can indeed pack circuitry a million times more sophisticated than anything that went to the moon. That uses a lot less power, has vastly more efficient solar panels (at least while it’s near a star), etc. Whether that kind of hardware is “space ready” is another question. This may be why they want to send a bunch, to account for failures by brute force instead of hardening the hardware to a degree where it becomes too heavy.
I can imagine any debris hitting you in interstellar space really ruins your day.