Assembly of the rover Europe and Russia plan to send to the Red Planet next year is complete.
Engineers at Airbus in Stevenage, UK, displayed the finished vehicle on Tuesday ahead of its shipment to France for testing.
Called "Rosalind Franklin" after the British DNA pioneer, the six-wheeled robot will search for life on Mars.
It has a drill to burrow 2m below ground to try to detect the presence of microbes, either living or fossilised.
The project is a joint endeavour of the European and Russian space agencies (Esa and Roscosmos), with input from the Canadians and the US.
Although the rover's build took just nine months, development work at component and instrument level has consumed more than a decade (the initial feasibility study was started in 2004).
Lift-off atop a Proton rocket is scheduled for July 2020. It is an eight-month cruise to Mars, with the landing on an ancient equatorial plain targeted for 19 March, 2021, around 0600 local Mars time.
China and the US are preparing their own rovers for launch in the same departure window as Rosalind Franklin.
China's vehicle, dubbed XH-1, is a slightly smaller concept. The Americans are assembling a near-copy of the one-tonne Curiosity robot that has been investigating the Red Planet for the past seven years. Their machine is codenamed currently simply Mars 2020./BBC news