NASA’s decision this August to send up a robotic vehicle to steer the Hubble Space Telescope back to Earth is looking like a very bright idea indeed. The space agency’s calculations now show that uncontrolled re-entry would carry a 1 in 250 risk of death or serious injury to people on the ground, far greater than the 1 in 10,000 risk that NASA deems acceptable.
Without repairs, Hubble’s batteries and gyroscopes are expected to fail by 2007. The spacecraft has no propulsion system, so its orbit will gradually decay until it re-enters the atmosphere at an altitude of 122 kilometres in about 2020. Being relatively…
