Atlantis Launch Scrubbed

NASA canceled today's attempt to launch space shuttle Atlantis after a sensor in an emergency engine cutoff system failed again:

Of the four engine cutoff sensors, ECO sensor number three gave false readings. NASA's current Launch Commit Criteria require that all four sensors function properly. The sensor system is one of several that protect the shuttle's main engines by triggering their shut down if fuel runs unexpectedly low.

Atlantis' scheduled launch on Thursday was delayed after two of the four engine cutoff, or ECO, sensors in the shuttle's external fuel tank gave false readings. A third sensor failed after the tank was drained of fuel.

It's unbelievable that NASA's rocket scientists and engineers haven't been able solve this problem in two years.