In a historic Election Day showdown where every vote matters, the outcome of one precinct could be determined by just two voters.

NASA announced Tuesday that astronauts Shane Kimbrough and Kate Rubins had cast their absentee ballots in zero gravity, fulfilling a NASA motto to "vote while you float."

Astronauts begin their voting process a year before they launch, selecting which elections they wish to participate in while they're in space, according to NASA. Kimbrough and Rubins received an absentee ballot addressed to their home in "lower Earth orbit," thanks to a 1997 Texas election law that established a procedure allowing astronauts to vote.

Kimbrough is the only American currently aboard the International Space Station (ISS). Rubins returned to Earth on Oct. 30, but not before casting her vote.

In an interview for, Rubins said that she was looking forward to voting from space.

"It's very incredible that we're able to vote from up here and I think it's incredibly important for us to vote in all of the elections, so yes, I definitely do plan on voting."

This story originally appeared on NBC News' website.