NASA to attempt Sunday launch: all four sensors must work

William Atkins
Sunday, 09 December 2007 04:28

Science - Space

The engine cutoff sensors to the hydrogen tank within the external tank aren’t behaving themselves. All four must work on Sunday, December 8, 2007, for NASA to launch STS-122 and the shuttle Atlantis for its delivery and installation mission to the space station.             

The fuel gauges, which are located near the bottom of the external tank, prevent the Space Shuttle Main Engines (SSMEs) from running without fuel and also are used to detect leaks in the fuel system. They have been causing NASA a pain in their external tank for several years now. And, they might just prevent the launch on Sunday, December 9th.

NASA officials have tightened a rule for launching the shuttle. All four sensors must work to be able to launch. In previous missions, only three had to be working properly for an acceptable launch.

However, the Astronaut Office, headquartered at the Johnson Space Center, in Houston, Texas,  made the suggestion that all four sensors need to be working properly before launch since three of them have already shown signs of problems. The astronauts want a safe flight to space, so strongly recommended the rule be stiffened.

The NASA brass agreed!

The five-minute launch window has also been reduced to only one minute so that the path taken by the space shuttle will be a more direct route to the International Space Station. When launching, the shuttle will be more closely in the same orbital plane as the station so will require less fuel in the external tank, just to give more leeway in the liquid hydrogen tank, which is where the sensors have been failing.

NASA has also installed new instruments to monitor the behavior of the fuel gauges.

In all, NASA mission managers are confident that Atlantis is good–to-go on Sunday. However, a lot needs to work to the advantage of NASA, especially four good sensors, for the mission to be able to lift off.

NASA will broadcast the Atlantis mission on NASA TV at: http://www.nasa.gov/multimedia/nasatv/MM_NTV_Breaking.html. Coverage begins at 10:00 a.m. EST, with a launch scheduled now for 3:21 p.m. EST.