Engineers are planning to test the Atlantis space shuttle's engine cutoff (ECO) circuitry again in an effort to find the problem that has delayed the launch of the craft.

Wayne Hale, Shuttle Program Manager, has explained that engineers are planning to implement more tests in an effort to determine any bad wiring that may have caused the ECO to fail a number of pre-flight tests.

Spaceflight Now reports that the ECO sensors form part of a backup system and rely on the change in the electrical resistance of platinum to demonstrate levels of hydrogen fuel in the craft's tanks.

The platinum wires' resistance changes depending on whether they are exposed to cryogenic temperatures but the problems in Atlantis emerged during some test runs when the sensors were not revealing any changes.

As a result, the engineers will be looking to find out if faulty wiring might be to blame for the problems and if so where and how this can be fixed.

Source:

Atlantis to be fueled again for more troubleshooting, 11/12/07
http://www.spaceflightnow.com/shuttle/sts122/071211tankingtest/

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