Rock from Mars heads home after 600,000 years on Earth

Tiny piece of meteorite from London's Natural History Museum will be used by rover exploring red planet

A small piece of rock will be hurled into space this week on one of the strangest interplanetary voyages ever attempted. A tiny piece of Martian basalt the size of a 10p coin will be launched on board a US robot probe on Thursday and propelled towards the red planet on a seven-month journey to its home world.

This extraordinary odyssey, the interplanetary equivalent of sending coals to Newcastle, will form a key part of Nasa's forthcoming Mars 2020 expedition. Space engineers say the rock - which has been donated by the Natural History Museum in London - will be used to calibrate detectors on board the robot rover Perseverance after it lands and begins its search for signs of past life on the planet.