A technical issue with an engine cut-off (ECO) sensor inside space shuttle’s external tank forced NASA officials to scrub Friday’s STS-115 launch attempt. This system of sensors is one of several that protect the shuttle’s main engines by triggering their shut down if fuel runs unexpectedly low. ECO sensor #3, one of four inside the liquid hydrogen section of the orange external tank, continued to read “wet” after the fuel was drained from the tank today. The other three ECO sensors appear to be in working order.

Shuttle Program Manager Wayne Hale stated today: “We’re going to review the data overnight. If everything is performing as we expect and we just have one sensor continuing to be a bad actor, we’ll launch tomorrow.”

NASA is now targeting a launch time of 11:15 AM EDT Saturday, September 8th, which is the final flight opportunity for Atlantis in the current launch window. If further technical issues or bad weather prevent tomorrow’s scheduled liftoff, STS-115 will have to wait until late September or early October.

Launch coverage of tomorrow’s launch attempt begins on NASA TV at 5:00 AM EDT. High-definition launch coverage will air on HDNet starting at 7:00 AM EDT.

Further reading:

• Spaceflight Now
• Space.com