The ailing Hubble space telescope is expected to be given a reprieve today when the head of the US National Aeronautics and Space Administration (Nasa) announces the go-ahead for a servicing mission in 2008.
Michael Griffin, Nasa's administrator, is due to give his final decision later today about the feasibility of refurbishing Hubble with new instruments that could extend its working life beyond 2012. The fourth Hubble servicing mission was cancelled after the Columbia shuttle disaster, prompting speculation that the telescope may have to be abandoned because of the risk of sending astronauts to the telescope's high orbit.
Mr Griffin is keeping his decision secret but insiders believe he strongly favours a mission to save the Hubble telescope from imminent technical failure after its 16 years in space. "We're certainly hoping that's the case. He's known to be very pro-Hubble but he's also got to look at the risk," said Professor Martin Barstow of Leicester University.
Mr Griffin ordered an extensive risk assessment to be carried out and with two successful shuttle missions under Nasa's belt since the spacecraft were grounded after the Columbia disaster in February 2003, commentators believe the conditions are right for a Hubble servicing mission to be approved.
One of the dangers of sending astronauts to perform a space walk on Hubble is that, unlike missions to the International Space Station, there is no "safe haven" if things go wrong.
One suggestion is that a second shuttle could be made ready for launch if any serious problems are encountered.