Nasa extends Atlantis mission
Tuesday, 12 Jun 2007 10:22
A fourth spacewalk has been added to the mission
Nasa has decided to extend the Atlantis shuttle mission to the International Space Station (ISS) by two days to allow time for an additional spacewalk so that astronauts can fix a tear in the spacecraft's heat shield.
The STS-177 mission had originally been planned to last for 11 days, during which time crew members would work to improve the power supply to the orbiting outpost.
But following take-off at the weekend a 10cm tear was spotted in the heat shield. After analysis of the tear by a camera at the end of Atlantis' robotic arm, mission managers decided to fix the problem while in space instead of waiting to return to Earth.
"It was 100 per cent consensus that the unknowns in the engineering analysis and the potential damage…was not acceptable and we wanted to go and fix it," John Shannon, chair of the mission management team, said in a briefing.
Nasa is particularly cautious after the Colombia shuttle sustained damage to its heat shield in 2003, causing it to burn-up on re-entry to the Earth's atmosphere. All seven astronauts onboard died.
Yesterday the first spacewalk was completed by STS-117 mission specialists Jim Reilly and John 'Danny' Olivas. During the six-hour task the astronauts installed a new truss segment and made power, data and cooling connections between the ISS and the segment.
They also released locks and launch restraints on the segment's solar arrays (panels); these arrays are set to be unfurled later today.
Enhanced power generation capacity is necessary to lay the groundwork for Europe's Columbus module to join the ISS later this year.
