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NASA thinks that the technologies needed to launch an interstellar probe to Alpha Centauri at a speed of up to 0.1c could be ready by 2069:
In 2069, if all goes according to plan, NASA could launch a spacecraft bound to escape our solar system and visit our next-door neighbors in space, the three-star Alpha Centauri system, according to a mission concept presented last week at the annual conference of the American Geophysical Union and reported by New Scientist. The mission, which is pegged to the 100th anniversary of the moon landing, would also involve traveling at one-tenth the speed of light.
Last year, Representative John Culberson called for NASA to launch a 2069 mission to Alpha Centauri, but it was never included in any bill.
Meanwhile, researchers have analyzed spectrographic data for the Alpha Centauri system and found that small, rocky exoplanets are almost certainly undiscovered due to current detection limits:
The researchers set up a grid system for the Alpha Centauri system and asked, based on the spectrographic analysis, "If there was a small, rocky planet in the habitable zone, would we have been able to detect it?" Often, the answer came back: "No."
Zhao, the study's first author, determined that for Alpha Centauri A, there might still be orbiting planets that are smaller than 50 Earth masses. For Alpha Centauri B there might be orbiting planets than are smaller than 8 Earth masses; for Proxima Centauri, there might be orbiting planets that are less than one-half of Earth's mass.
In addition, the study eliminated the possibility of a number of larger planets. Zhao said this takes away the possibility of Jupiter-sized planets causing asteroids that might hit or change the orbits of smaller, Earth-like planets.
(For comparison, Saturn is ~95 Earth masses, Neptune is ~17, Uranus is ~14.5, and Mars is ~0.1.)
Planet Detectability in the Alpha Centauri System (DOI: 10.3847/1538-3881/aa9bea) (DX)
(Score: 2) by Immerman on Thursday December 21 2017, @02:57PM
Actually, a single layer of graphene blocks ~2.5% of light, pretty much across the spectrum, and the effect stacks - so at 10nm (30 layers) you're blocking ~53%. Working out something more opaque (and reflective rather than absorbent) will no doubt be a challenge. We'll have to see see what material scientists can accomplish given a motive.
Transmission will indeed be a challenge, I've got no answers for that, except that RF is almost certainly out - as you say, there's not really any quiet place in the spectrum. I'd bet on a carefully tuned laser myself. And that communication would be strictly one-way - With the mass and power constraints I'd expect it'd be nigh-impossible for it to detect an interstellar signal. Though... perhaps the launching laser could be tuned and modulated to be readily detected at that distance.
And hey, even if we never heard back from the probe itself, we'd now have a big honking launching laser that would be of great help for moving stuff around the solar system as well...