Bat Attempts to Stow Away on Space Shuttle
A stowaway bat is seen clinging to the external tank of the space shuttle Discovery at Launch Pad 39A during a March 15, 2009 launch countdown.
Credit: collectSPACE.com via NASA.

CAPE CANAVERAL, Fla. - A small bat appears to be trying to hitch a ride aboard the space shuttle Discovery from its perch on the spacecraft?s attached external tank as NASA counts down to a planned Sunday evening launch.

Mission managers said the tank-clinging fruit bat is unlikely to pose a risk for the shuttle, and will probably fly away when Discovery blasts off this evening at 7:43 p.m. EDT (2343 GMT) from Pad 39A here at NASA's Kennedy Space Center.

"It's not expected to be a debris problem," NASA spokesman Mike Curie told SPACE.com. The bat is between one quarter and one third of the way up on the north side of the shuttle's huge orange external fuel tank, which is the side that faces away from the orbiter. It could be seen in a NASA camera view caught by collectSPACE.com, a SPACE.com partner.

It was first noticed this morning while the fuel tank was being filled with its super-chilled liquid hydrogen and liquid oxygen propellant. NASA does not think the bat has frozen in place, though, because the tank's surface temperature is between 58 and 70 degrees Fahrenheit at the bat's location.

This isn't the first time a bat has taken up position on a shuttle's fuel tank on launch day.

"On STS-72 there was a bat, but it flew away during launch," Curie said, referring to the 1996 flight of the shuttle Endeavour. That bat did not harm the shuttle at all.

Birds and bats can pose a hazard to space shuttles if they impact and damage an orbiter's sensitive heat shield tiling. This thermal coating protects the shuttle from burning up in Earth's atmosphere when it re-enters.

In 2005, a large turkey vulture ran into the back of the space shuttle Discovery's external tank. Luckily, this impact didn't harm the shuttle, which was on the opposite side of the tank. Ever since, NASA launch officials use radar to track flocks of birds during a launch. NASA also fires loud canons to scare away birds when the shuttle is heading in to touch down on the long landing strip at Kennedy Space Center.

Discovery is poised to deliver new solar arrays and a new station crewmember to the International Space Station. Commander Lee Archambault will lead the seven-member STS-119 crew on the planned 13-day mission.

Discovery is also ferrying Japanese astronaut Koichi Wakata to the space station, where he will replace NASA astronaut Sandra Magnus as a member of the outpost's three-person crew. Coincidentally, Wakata - Japan's first long-duration astronaut - was also part of the STS-72 crew aboard Endeavour when the last bat tried to hitch a ride into space.

Click here for more on Discovery?s stowaway bat and the shuttle mission from collectSPACE.com.

SPACE.com is providing continuous coverage of STS-119 with reporter Clara Moskowitz in Cape Canaveral and senior editor Tariq Malik in New York. Click here for mission updates and SPACE.com's live NASA TV video feed. Live Coverage is under way.