Nasa continues its efforts to diagnose the problems on the Hubble space telescope and return the veteran space mission to full operation. Science operations were suspended on 13 June when the computer responsible for the specific instruments began to malfunction. The science instruments themselves were automatically placed into safe mode, and the rest of the telescope continued to function normally. Tests of the payload computer indicated the problem was not in the computer’s memory as originally thought, but somewhere else in the science instrument command and data handling unit (SI C&DH). The team is investigating a unit that formats commands and data within the telescope, and a power regulator designed to ensure a steady voltage to the payload computer’s hardware. Once the faulty piece of equipment has been identified, the team will most likely have to switch to backup hardware that is already installed on the spacecraft. This is a delicate operation that will be practised in computer simulations on Earth first. A similar operation took place in 2008 after a previous formatting unit failed. A servicing mission in 2009 then replaced the entire SI C&DH unit with the one currently being used. Full science operations are expected to resume in due course.