Nasa will be sending an uplifting message to the Voyager 1 spacecraft on its 40th year anniversary and the message will be chosen by open voting on its "Vote for the #MessageToVoyager" page.
The message will be chosen from 10 finalists picked up from thousands of tweets that Nasa received through its #MessageToVoyager campaign. Voting is open till Tuesday, 29 August. According to Nasa, every message takes about 19 hours and 18 minutes to reach Voyager.
Nasa says the idea of sending the message to Voyager was inspired by a copper gold-plated disc that was attached to the craft. The disc contains several messages for the finder to identify earth and humans and has a special message from humanity penned by former US president Jimmy Carter and former UN secretary general Waldheim.
Voyager 1 is the first man-made object to reach interstellar space, the point where the sun's influence in terms of flow of material and magnetic field ends, according to Nasa. Voyager, which went interstellar in 2012, is Nasa's longest running space mission, with the craft over 20 billion km away and travelling toward the Ophiucus constellation.
The 10 messages all fall within a set of guidelines framed by Nasa. The length of the message is limited to 60 characters and the text contains only letters, numbers and spaces. They were chosen by a team at the Jet Propulsion Laboratory, Nasa and the Voyager mission.
Nasa will transmit the winning message on 5 September and it will reach the vicinity of Voyager 1 the following day.
The Voyager mission will run as long as the craft is able to generate its own electricity for "continued science instrument operation". That time is estimated to be around the year 2020 after which the mission formally comes to an end.