NASA is reconsidering its support for an innovative experiment designed to capture direct evidence of elusive antimatter. At stake is an unusual 16-nation effort, led by a Nobel Prize winner, that until recently was cited by agency managers as proof that the space station can host high-quality science. The reevaluation is the latest fallout from President George W. Bush's decision in January to concentrate space station work on experiments related to human exploration (ScienceNOW, 14 January).
A full review of the project, called the Alpha Magnetic Spectrometer (AMS), could begin this summer, says Bernard Seery, a deputy chief of NASA's biological and physical sciences office. AMS was conceived a decade ago by Massachusetts Institute of Technology physicist Samuel Ting, who won the Nobel Prize in 1976 for discovering a new particle. It is designed to detect antimatter atoms, which have never been found in nature. Theoretically, antimatter should make up half the universe, and its apparent paucity remains a cosmological mystery.
After high-altitude balloon experiments failed to detect any evidence of such atoms in cosmic rays, Ting proposed putting in space a large magnet with sensitive detectors. Attached to a space station truss, AMS would monitor high-energy particles, noting their velocity and their path through the instrument. Ting hopes evidence of antimatter atoms can be extracted from the data. NASA was to provide the container that holds AMS and transport it to the space station via the shuttle.
If NASA pulls its support, Seery says one option would be to launch AMS on an expendable launch vehicle and fly it freely in space. That change could make the project more expensive, however, because it would require purchase of a launcher as well as a "major redesign" of the AMS hardware, says James Bates, the mission manager of NASA's portion of the project at Johnson Space Center in Houston.
Ting says that no one at NASA has told him of any potential review and that he expects NASA "to respect our international collaboration." But he also intends to meet next month with Craig Steidle, NASA's new exploration chief, to emphasize AMS's potential benefits for astronauts headed beyond Earth orbit. AMS could provide crucial data on cosmic nuclei, which would be vital to planning long-term human missions, Ting says. And a lightweight magnet similar to AMS might even help a future spaceship protect its human crew from dangerous cosmic rays.