It’s been a long time since anyone tried landing on Venus, one of the most hostile environments in the Solar System. Covered in sulphuric acid clouds, the surface temperatures approach 460 C (860 F) with atmospheric pressure 90 times that of Earth. Lead, zinc and tin are liquids, and the weight of the carbon dioxide air is roughly equal to that found a kilometre under the ocean – enough to crush a submarine.

Yet the planet is getting renewed attention – Japan’s Akatsuki mission successfully entered orbit in December 2015 and there are new missions planned from Nasa and Esa in the 2020s. Even Russia plans a follow up to their highly successful Venera and Vega missions of the 1970s and 80s. All of these missions involve orbiters, and will study the planet's atmosphere, magnetic field, and geography.

To really understand the planet one needs a lander. Landers can test the chemistry of the air and rocks at the surface, and do seismology to reveal what the interior of the planet looks like. The Venera D has a lander, but it has a mission lifetime of three hours based on the batteries it can carry. The previous record for surviving on the surface was set by the Soviet Union’s Venera 13 lander, which touched down in 1982. It lasted 127 minutes in this toxic, hazardous environment.