CAPE CANAVERAL, Fla. NASA engineers are studying an apparent engine controller glitch in a backup system on the space shuttle Discovery, in the hopes of solving the issue in time for the shuttle's scheduled launch tomorrow.
The glitch is affecting the backup computer controller on Discovery's Main Engine No. 3, but further details have not yet been released. During the shuttle's main engine checkouts, the backup controller for engine 3 did not turn on as expected, NASA officials said in a statement. Engineering teams are continuing to investigate the issue.
Earlier today (Nov. 2), shuttle engineers noticed a separate problem with the same backup computer system, but the issues were said to have been resolved. [ GRAPHIC: NASA's Space Shuttle From Top to Bottom]
"After addressing a couple issues last night, our countdown work is currently back on schedule," NASA test director Steve Payne told reporters during a mission status briefing this morning.
Discovery is slated to blast off tomorrow (Nov. 3) at 3:52 p.m. EDT (1952 GMT) from a seaside pad here at NASA's Kennedy Space Center. The mission has been delayed by two days by other technical issues that have since been solved.
The shuttle's STS-133 mission management team is scheduled to meet at 5 p.m. (2100 GMT) to discuss the issue and make a decision on further action.
If the issue is resolved, NASA would then proceed with plans to begin fueling Discovery's external tank early tomorrow morning for its afternoon launch into space.
Space shuttle Discovery will begin its 39th and final mission to the International Space Station when it blasts off this week. Weather forecasts continue to show a 70 percent chance of acceptable conditions for launch tomorrow.
On its 11-day mission, Discovery will haul critical spare parts to the space station, including a storage room and a humanoid robot to assist the crew of the orbiting laboratory.
Discovery was originally scheduled to launch Nov. 1. The space agency delayed the launch by one day after detecting helium and nitrogen leaks on the shuttle. Another day of delay, to allow time to complete repairs, pushed the launch to Nov. 3.
While the weather outlook for Wednesday looks promising, NASA is tracking some other storms that could stall Discovery's flight if it suffers another launch delay.
A weather front pushing down into parts of central Florida could cause concerns if Discovery's launch is stalled another 24 hours or more, according to Kathy Winters, NASA's shuttle weather officer.
NASA has until Sunday, Nov. 7 to launch Discovery within the current window. After that, the space agency would have to wait until early December to try again.
- GRAPHIC: NASA's Space Shuttle From Top to Bottom
- Gallery: Building Space Shuttle Discovery
- Video Space Shuttle Discovery: A Retrospective, Part 2, Part 3
Follow SPACE.com Staff Writer Denise Chow on Twitter as she covers Discovery's final space voyage from Cape Canaveral, Fla. for mission updates, new stories and a link to NASA's live webcast coverage.