I'm thinking speculatively. NASA is doing experiment with ion thrust tech. Assuming, that inside the next 5 years, we could create a probe which would take on the order of 30 to 50 years to reach Alpha Centauri: What problems would it have?
ie: Is the biggest challenge going to be communications back to Earth? Maybe a small probe can't transmit a strong enough signal (especially since we'd be essentially looking straight at the star, from our point of view) ?
Or Maybe the challenge in transmitting is really the targetting, to keep the Antenna pinpointed on Earth?
Or would there be problems with powering the probe over a 50 year journey (at which point we'd really want it to have several years left of usable lifetime) ?
Or is there problems with space probes, outgassing or other gradual losses which would cause the device to decay after 50 years of vaccum?
Do the long-lasting Voyager probes help answer any of these issues? I know they are MUCH closer to earth than what I'm talking about, but at least they are still alive and transmitting…
This is a speculative question, so I hope it is allowed by the forum rules. I'd like to think about how such problems can be overcome — but first I really need to know what the problems might be. So I'm looking for thoughts or info…
EDIT: perhaps I was optimistic. if a 50 yrs travel time is not practical, even with a long duration thrust like ion drive, then feel free to posit a longer flight time.
Best Answer
Probably the single biggest obstacle is detection and avoidance of objects in space. To get to Alpha Centauri in 40-50 yrs the probe would be traveling at relativistic speeds (~1/10 the speed of light). All collision detection and avoidance would need to be handled by onboard systems since the ground controllers would have no direct control. You have to realize that at the speeds involved, the probe would cover the distance between the Earth and Moon in about 10 secs or so. The volume sweep of the probe in that time is enormous, and because of the speeds involved, and the limit of the speed of light, the device will cover at least a tenth to a fifth of the distance to an obstacle after detection in an active system. Passive systems would be good early warning, but regardless the system will need massive computational power to calculate projected courses of obstacles for avoidance.
For these reasons, there might need to be a series of probes, a few probes that would be "disposable" that act as pathfinders, followed by more critical probes that contain the more important science packages.