国际英语新闻：NASA Sets Endeavour's Last Launch for April 29

The space shuttle Endeavour is set to blast off on its final mission at the end of this month.  The U.S. space agency made the official announcement Tuesday afternoon after a thorough review of the shuttle's readiness.

NASA says space shuttle Commander Mark Kelly and his five crewmates will blast off on Endeavour's last mission on April 29.

Bill Gerstenmaier, NASA's associate administrator for Space Operations, told reporters Tuesday that NASA officials gave the shuttle a clean bill of health. 

"We reviewed everything," said Gerstenmaier. "We spent quite a bit of time talking about all the things, and I think the team was unanimous and we're ready to go fly."

NASA managers ran extensive tests on an external tank that was damaged during Hurricane Katrina, which struck the U.S. Gulf coast in 2005.  NASA determined the tank is ready for launch, without the same metal support beams that were on the shuttle Discovery's tank.  Those supports, or stringers, cracked while Discovery was on the launch pad, delaying its lift-off by several months.

Gerstenmaier also said engineers added more, tougher tiles to the underside of Endeavour's wings and fuselage for enhanced protection from launch-related debris.

NASA concluded that the shuttle and space station's equipment, as well as support systems and personnel, are ready for the mission.

The primary objective of Endeavour's 14-day journey in Earth orbit is to deliver the Alpha Magnetic Spectrometer  to the International Space Station.  The spectrometer, or AMS, is a sophisticated detector that will help researchers study the formation of the universe.

"It will allow us to just learn more about dark matter, which makes up a large portion of the universe, which we really don't understand why it's there, or matter that we can't see with classical instruments.  So it was very interesting hearing about AMS," said Gerstenmaier.

The spectrometer will look for elusive evidence of anti-matter by searching for anti-carbon and anti-helium molecules among all discernible particles.

This will be the last mission for Endeavour, and the second-to-last mission for the U.S. shuttle fleet.  NASA is retiring the shuttles in order to focus on developing the next generation of spacecraft that could go beyond low-Earth-orbit.