It doesn't have to be scientifically accurate to a fault. Nor does it have to be full of technobabble. I'm looking for a yarn with a general feeling of authenticity, i.e.
1) not set in 100'000 years in the future during an intergalactic civil war with the Empire of Glerg or some shit, and
2) without any convoluted space politics.
For example: two astronauts are on a spacewalk to repair a damaged solar panel on the International Space Station. They discover the source of the damage: a strange object. FROM THE FUTURE! (ignore that last part)
Or... some guy is working the night shift at a SETI observatory. Suddenly, one of the computers picks up a mysterious signal: a rhythmic pulse spelling out a cryptic series of letters: FHUTA
I just pulled that out of my arse, obviously, but you get the idea.