$2 billion cosmic ray detector at home on station

The International Space Station's signature science experiment, the Alpha Magnetic Spectrometer, is securely attached to the outpost.

Endeavour astronauts this morning lifted the $2 billion particle physics detector from the shuttle's payload bay and attached it to the right, space-facing side of the station's structural truss, completing their top mission objective.

The device was confirmed attached to the Starboard 3 truss segment at 5:46 a.m. EDT.

"AMS is probably the most significant scientific experiment on the station," radioed Endeavour mission specialist Greg Chamitoff. "We all look forward to seeing what AMS will discover about the nature of the universe."

Power and data connections must be made before the 7.5-ton instrument is operational, but it should begin collecting data soon.

AMS will sift through cosmic rays travelling from distant reaches of the universe, characterizing the high-energy particles passing through it in the hopes of better understanding the structure and origin of the universe.

AMS is designed to look for dark matter, the mysterious, unseen substance believed to account for most of the universe's mass; antimatter, which according to the Big Bang theory should have existed in equal quantity to matter at the universe's creation; and "strange" matter created experimentally but not found on Earth. 

A prototype instrument flew a test run on shuttle Discovery in June 1998, but it has since been upgraded with more sensitive detectors. It features a large permanent magnet and eight detectors to measure particles' speed, direction, mass and charge.

AMS will now operate as long as the station remains in service, at least until 2020.

Coming up at 6:11 a.m., Endeavour crew members will field questions submitted and voted upon by the public in an interview with journalist Miles O'Brien. Nearly 2,300 people submitted nearly 1,900 questions to the Google/PBS NewsHour event, and more than 14,000 votes cast.

Chamitoff and Endeavour pilot Greg Johnson aren't expected to partcipate since this morning's robotic operations to install AMS ran behind schedule.

More media interviews are planned at 10:01 a.m.

The crew is also preparing for the mission's first of four planned spacewalks. Drew Feustel and Greg Chamitoff are scheduled to float outside the station at 3:16 a.m. Friday.

The Endeavour crew is scheduled to go to bed today at 2:36 p.m.