The United States Chess Federation and NASA are hosting a correspondence
chess match with an American astronaut, Dr. Greg Chamitoff, onboard the
International Space Station in which the public can participate. The
astronaut is playing against elite grade K-3 players, who choose 4
possibilities for each move, which the public selects by voting. The
match begins tomorrow, and USCF estimates that the moves will average
about two days each, maybe more or less. As far as I can tell, voting on
the moves is pretty straightforward on the USCF website, as there
doesn't seem to be a link for registration on the match's webpage.
Here is a NASA press release on the match.