The four astronauts set to make history this week by becoming the first ever all-civilian crew to orbit the Earth have posed for a photograph ahead of the mission - with a hidden message included.
SpaceX's Inspiration4 mission is set to blast off during a 24-hour window starting at 11am Thursday NZ time, carrying billionaire entrepreneur Jared Isaacman and three other spaceflight novices.
All four looked relaxed, smiling for the picture ahead of launch, with eagle-eyed internet users noting a pertinent message in Morse code behind them.
It reads "Ad astra", a Latin phrase that translates as 'to the stars' which, although literally not true of this mission, is an apt metaphor for the record-breaking crew.
Isaacman can fly commercial and military jets, and is officially designated 'commander' of the mission, while geoscientist Sian Proctor is the 'pilot'.
However neither Isaacman, Proctor or the others onboard - Hayley Arceneaux and Chris Sembroski - will play any part in operating the spacecraft.
All four have spent five months getting ready for the three-day mission which will send them around the globe every 90 minutes at more than 27,400km/h.
The target altitude for the mission is 575km which is beyond the orbit for the International Space Station.
Once in orbit, the crew will perform medical experiments with "potential applications for human health on Earth and during future spaceflights", Reuters reported.
Vice's Motherboard reports this is the second 'Easter Egg' for space fans recently.
NASA's Jet Propulsion Laboratory (JPL) embedded a secret binary code message in a parachute deployed to slow the descent of the Mars Perseverance rover.
The pattern read "Dare Mighty Things", JPL's unofficial motto, as well as the organisation's coordinates in California.
SpaceX is run by Tesla founder Elon Musk who, unlike fellow billionaires Richard Branson and Jeff Bezos, isn't going along for the space ride.
Virgin Galactic and Blue Origin, run by Branson and Bezos respectively, both had their first tourist launches recently - but they were sub-orbital and crews were flying for only a matter of minutes.
Musk and Bezos are currently involved in a war of words and a court case involving SpaceX's internet-providing Starlink satellites and a decision by NASA to award a lunar landing contract to SpaceX instead of Blue Origin.
