Its cargo is so precious it could help answer some of humanity's biggest existential questions. That's why there is so much excitement about the return of the OSIRIS-REx spacecraft, which will drop a capsule full of 4.5 billion-year-old space dust back to Earth on Sunday. The 8.8oz (250g) sample, audaciously grabbed from the mountain-sized asteroid Bennu in October 2020, could shed light on how life emerged on Earth and whether we are alone in the universe. OSIRIS-REx began its two-year, four-month journey home in May 2021, having been powered down to conserve energy during the trip. In the early hours of Sunday, however, the probe will be woken from this low-power mode ahead of its all-important delivery.