By Allison KuboArtistic representation of OSIRIS-REx over the asteroid Bennu. In 2016, the OSIRIS-REx probe left Earth but unlike most other probes on their journey out to space, OSIRIS-REx does intend to return home. If all goes well, OSIRIS-REx will return to its home in 2023 carrying a precious sample.As of 2018, OSIRIS-REx has been orbiting the asteroid Bennu. Bennu is about the size of the Empire Statebuilding but it is older than the Earth itself. Bennu represents the composition of parts of the early solar system.It is proposed that Bennu and the carbonaceous chondrites are the source of Earth’s water.