You don’t have to be big to challenge Einstein. A pocked ball just 36 centimetres wide is the latest space probe tasked with measuring general relativity, one of the cornerstones of modern physics.

The Laser Relativity Satellite, or LARES, is a tungsten sphere with reflectors mounted in 92 holes punched into its surface. It is due to launch from Kourou, French Guiana, on a new European Space Agency rocket called Vega, designed to cheaply launch payloads of less than 2500 kilograms. The launch window opens on 13 February.