TIM FURNISS / LONDON
NASA engineers work on a fix after problem is found on two orbiters. Meanwhile, other craft await engine checks
Launch of the next Space Shuttle mission, STS 107, scheduled for 19 July, will be delayed at least a "few weeks" following discovery of hairline cracks in the metal flow liners inside the liquid hydrogen propellant lines of two Space Shuttle main engines.
Cracks were detected in engines on the orbiters Atlantis and Discovery. The orbiter Columbia, being prepared for the STS 107 mission, and Endeavour, recently returned from its STS 111 mission, will need to be inspected while NASA assesses the implications, quantifies the risk and develops a fix for the problem.
Engineers found 2.5-7.5mm cracks in one flow liner on one engine each on Atlantis and Columbia, but only through more intensive inspection techniques not used routinely, rather than standard visual inspections. The possibility that the lines could rupture, at worse causing fragments to be ingested into the engine, is enough to cause NASA to be cautious.
"These cracks may pose a safety concern and we have teams at work investigating all aspects of the situation. This is a very complex issue and it is early in the analysis," says Ron Dittemore, Space Shuttle programme manager.
The delay to STS 107, a two-week independent science mission called Freestar, may have a knock-on effect on future Shuttle launches, including the next International Space Station (ISS) mission, STS 112 Atlantis, scheduled for August, which may leapfrog ahead of 107 when launches resume.
The orbiter Endeavour landed at Edwards AFB, California, on 19 June after three wave-offs from a planned Kennedy Space Center, Florida landing, because of bad weather. The fourth ISS expedition crew, which returned to Earth on Endeavour, had flown a mission lasting 196 days, breaking the 188-day US record set by Shannon Lucid on a Mir space station flight.
The STS 111 mission delivered cargo aboard the Leonardo module - which also returned to Earth with cargo - and delivered the fifth expedition crew to the ISS.
NASA has extended to September 2008 its $1.15 billion contract with Lockheed Martin Space Systems to build 35 external tanks for the Space Shuttle, slowing production to six a year.
Source: Flight International
