A British-built spacecraft launched on Saturday is now in “cruise mode” as it settles down for a five billion mile trip to Mercury.
Scientists will have to wait another seven years before BepiColombo delivers two orbiters to circle the planet closest to the sun.
The spacecraft was blasted free of the Earth’s gravity by an Ariane 5, the European Space Agency (ESA)’s most powerful heavy lift rocket.
Soon after the launch from the European space port at Kourou, French Guiana, cameras on the craft took a series of “selfies” showing the successful deployment of its 30-metre (98ft) wide solar panels and radio antennae.
In 2020 BepiColombo will sweep round the Earth at the start of a complex series of fly-bys designed to brake against the sun’s enormous gravitational pull.
The next stop is Venus, which the spacecraft will fly round twice collecting data on the way, followed by six fly-bys of Mercury.
BepiColombo will arrive at its destination on December 5, 2025. The two orbiters, one European and the other Japanese, will then detach from their “mothership” and start investigating the planet.
ESA’s science director Gunther Hasinger said: “There is a long and exciting road ahead of us before BepiColombo starts collecting data for the science community.
“Endeavours like the Rosetta mission and their ground-breaking discoveries even years after their completion have already shown us that complex science exploration missions are well worth the wait.”
A critical point will come when the spacecraft’s futuristic electric ion thrusters are switched on.
This will be done automatically by the on-board computer.
BepiColombo is the first mission to use the Star Trek-style “impulse drive” technology to reach another planet.
It has four of the engines. Two will fire at a time, expelling electrically charged atoms of xenon gas to produce about an ounce-worth of force that can be sustained for long periods of time.
Justin Byrne, head of science at Airbus Defence and Space, which built the Mercury Transfer Module carrying the orbiters in Stevenage, said: “The engines will be switched on in a few days and that will be the crowning glory. Then we have seven years to wait for the science.”