at the end of the decade. our correspondent david willis reports. venus is the closest planet to earth, and similar in size, mass, density and composition. in recent years, it's received less attention than mars and other destinations in the solar system, primarily because it's so hot. its dense atmosphere traps heat from the sun, leading to temperatures of more than a70 celsius in places. interest in venus was rekindled after astronomers said they had detected a molecule in the clouds which could be a possible sign of life. nasa is now planning two robotic missions later this decade, one of which will analyse the planet's atmosphere, whilst the other will map its surface. these two sister missions, both aimed to understand how venus became an inferno—like world, capable of melting lead at the surface.