Designing a mechanical rover to explore the surface of Venus

Such is our fascination with Mars that it’s easy to assume that it’s our closest neighbour. The subject of songs, books and films, the Red Planet has been intensely studied by orbiting probes, landers and rovers. It’s currently the only body in the universe that we know of that’s entirely populated by robots; and it’s the target for projected crewed missions in future decades.

But Mars isn’t our nearest neighbour. That distinction goes to Venus, which at its closest is around 25 million miles (40 million km) away, compared with Mars’s closest approach at 34 million miles (56 million km).

Jonathan Sauder, JPL

We know comparatively little about Venus, because it is so difficult to study. The planet’s surface is shrouded by a thick layer of opaque clouds, preventing its surface from being visible from Earth or even from orbit. Surface conditions are hellish. The temperature reaches 475°C, above the melting point of lead, and atmospheric pressure is more than 90 times that on Earth, enough to crush the hull of a nuclear submarine. Only ten landers have ever reached the surface, the most recent in 1985. Thanks to the temperature and the corrosive properties of the high-pressure CO₂ atmosphere, the longest any probe has stayed functional is two hours and seven minutes, achieved by the Soviet Venera 13 lander in 1982. No rovers have ever been sent to Venus.