A particle detector to be launched aboard shuttle Endeavour will help NASA learn how to protect future space travelers from radiation .

THE GIST

The Alpha Magnetic Spectrometer particle detector is scheduled to launch Friday aboard space shuttle Endeavour.

Once installed on the space station, the detector will provide scientists with their first detailed look at high-energy particles in cosmic rays.

An experiment also will provide information about using a magnet as a radiation shield for future spaceships.

A particle detector being prepared for launch Friday aboard space shuttle Endeavour is intended to answer some fundamental questions about physics, but it has a practical side as well -- testing a way to shield future astronauts from potentially harmful cosmic rays.

At the heart of the Alpha Magnetic Spectrometer, or AMS, is a 2-ton magnet that will bend high-energy particles into five detectors for analysis. Scientists hope to learn about dark matter, antimatter and other exotic phenomenon, but engineers at NASA who are developing next-generation spaceships are keen to learn how similar magnets could be used not to attract particles, but to repel them.

A magnetic shield would replicate the protective cocoon of Earth''s naturally occurring magnetic field, which helps protect the planet from harmful radiation.radiation

"Over the last six years, we've talked about using a magnetic shield on an interplanetary spacecraft so when a galactic cosmic ray or a solar particle comes toward the spaceship, a magnetic field would bend it out of the way," Trent Martin, who oversees the AMS project for NASA at the Johnson Space Center in Houston, told Discovery News."."

AMS, which is to be attached to the outside of the International Space Station, originally had a superconducting magnet five times stronger than the one currently installed on the instrument.

The cryogenically cooled magnet, however, would have run out of helium coolant in about three years, while the permanent magnet will keep the instrument operational throughout the 10- to 20-year lifetime of the space station. Scientists compensated for the lower-power magnet by adding more silicon trackers inside the detector.

"The technologies that were developed for the superconducting magnetic certainly provided a foundation for us," said Martin. "We built and certified for flight a human-rated superconducting magnet, which is exactly what you'd have to do to build an active radiation shield."to

Data from the use of AMS' permanent magnet will be useful in assessing the accuracy of computer models that are used to design radiation shielding, Martin added.

AMS has another side benefit for future exploration. The instrument will measure the amount of energy and type of  radiation in space, providing scientists with a more complete picture of the environment future astronauts will face.

"This will be extremely important if you send a man to a distant planet," said AMS lead scientist Samuel Ting, with the Massachusetts Institute of Technology. "A magnetic spectrometer on the space station is the only way to provide long-duration, high-precision measurements of charged cosmic rays."

The shuttle is scheduled to lift off at 3:47 p.m. EDT Friday from the Kennedy Space Center in Florida. It is NASA's next-to-last flight before the shuttle fleet is retired. NASA intends to develop new spaceships that can travel beyond the station's 220-mile-high orbit.