Major elections take place here in the US on Tuesday, and the presidential race in particular will be decided by a slim margin in a handful of battleground states. So in a democratic country where every vote counts, how do people without feet on Terra Firma make their voices heard?

NASA astronauts aboard the International Space Station (ISS) face this problem every time there is a general election. Fortunately, it’s not as thorny a problem as you might think. It all boils down to the same technology that makes communication with astronauts in space possible in the first place.

According to NASAthe process begins at home. Like any other American voter who wants to vote absentee, astronauts fill out a federal postal card application. With absentee voter status approved, astronauts download an electronic ballot while floating in zero-G.

Encrypted process

Then, NASA’s Space Communication and Navigation (SCaN) system sends the information via data relay satellites to a ground antenna in Las Cruces, New Mexico. From there, the vote is forwarded to the county clerk in the astronaut’s home state. The entire process is end-to-end encrypted. Only the astronaut and the clerk know how the vote was cast.

It may sound like a complex chain of events, but thanks to the physics of space travel, it’s considerably faster, cheaper and less complex than sending paper ballots on an 800 km trip to the ISS and back.

The system has been in place since 1997, when Texas (a state many astronauts call home, thanks to NASA’s strong presence there) passed legislation allowing electronic voting. The bill was largely the result of astronaut John Blaha’s desire to vote in the 1996 general election from the Russian Mir Space Station. He didn’t get his wish in time, but after the legislation passed, astronaut David Wolf was able to vote in local elections in Houston, Texas in 1997.

Spatial voter twice

Kate Rubins is the only astronaut to vote from space twicein the 2016 and 2020 general elections. Hopefully, given NASA’s increased commitment to human space travel, it won’t be the last.

As for US citizens who wish to vote from faraway places such as Antarctic? Surprisingly, it’s back to good old-fashioned paper ballots in most cases. As with astronauts, if you’ll be on an Antarctic base during voting season, you should think ahead and request a mail-in ballot. Once done, the process is simple and reliable. As this blogger points outflat postage is fairly consistent in Antarctica. He even received election flyers from various campaigns!