The inventors of Twitter could never have imagined how their creation would change the world. The social media platform has become the stage upon which some of the most important dramas—and pettiest comedies—of the last few years have played out. And now it'll help beam one lucky person's message into interstellar space, thanks to NASA's #MessageToVoyager contest.

The Voyager 2 and Voyager 1 spacecrafts launched on August 20 and September 5, of 1977. The probes set sail in opposite directions, bound for the outer reaches of space, each bearing a golden record imprinted with messages of peace and welcome from Earth to whomever else the spacecraft might encounter along the way.

The decades since have seen years of astonishing firsts from the two little probes. Voyager 2 has cruised past and sent back images from Jupiter, Saturn, Uranus, and Neptune. Just five years ago, Voyager 1 became the first craft to enter interstellar space.

In celebration of the 40th anniversary of the missions, NASA wants to give the people of Earth the opportunity to send a new message. The agency will transmit the single winning tweet into the area of deep space Voyager 1 now occupies.

To participate, compose a message of up to 60 characters. That includes letters, numbers, spaces, and punctuation. Tag your submission with #MessageToVoyager and post it to Twitter by August 15. You can also share it on Instagram, Facebook, Google+, or Tumblr.

Representatives from NASA, JPL, and the Voyager team will narrow down the entries, and then hold a public vote for the winner.

For full contest rules, check out NASA's #MessageToVoyager website.