The Hubble Space Telescope, which represents the greatest leap forward in astronomy since Galileo turned his telescope on the rings of Saturn, has been put in safe mode following age-related malfunctions in the gyroscopes that align it to the light of distant stars. They are not for navigation, as in ships and aircraft, but the craft uses the centripetal force of gyroscopic spin for steering. Gyroscopes align the telescope’s mirrors to targets with the accuracy of a sniper in Gibraltar hitting a bull’s eye in Kamchatka. The telescope has been in service since 1990 and, despite five service missions made by space shuttles, time has taken a toll on its crucial moving parts.
In almost three decades in orbit, far above atmospheric effects and the background light of civilisation which dims the vision of earthbound telescopes, Hubble has sent back 1.3 million observations amounting to about 150 terabytes of data. It has photographed light from shortly after the Big Bang (on an astronomical timescale) when the oldest known galaxy, GN-z11 in Ursa Major, was forming. Its observations support the theory that “dark energy”, undetected by instruments, pervades the universe. And its depth of field is extraordinary, ranging from the asteroids to the most distant stars. Downtime on such a useful instrument will set back our developing understanding of the universe, and of the physics which makes it tick.
As it goes into sleep mode, Hubble is living proof that the world’s space efforts need “trucks” shuttling between the earth and orbit. Since the US shuttle programme was discontinued in 2011, Nasa has had no way to repair or refurbish the Hubble telescope. Perhaps the next generation of space trucks will be delivered by private enterprise rather than governments. Until then, it appears, Hubble will have to stay in sleep mode.