Endeavour prepares for her final space station undocking

Shuttle Endeavour's right wing during her final space flight. (NASA)

The crew of shuttle Endeavour spent a busy Saturday aboard the International Space Station, transferring supplies to the outpost and preparing their ship for Sunday's departure and test of a high tech navigation aide.

The nine astronauts and cosmonauts living and working at the space station moved the last supplies and water bags from the orbiter over to the complex, and performed maintenance work on one of several carbon dioxide removal systems aboard the station.

Endeavour's all veteran crew of commander Mark Kelly, pilot Gregory H. Johnson and mission specialists Michael Fincke, Greg Chamitoff, Andrew Feustel and Roberto Vittori of the European Space Agency, arrived at earth's orbiting outpost on May 18.

The crew of six will say their goodbyes on Sunday morning to the station's crew of three, which includes station commander and Russian cosmonaut Andrey I. Borisenko, NASA astronaut Ron Garan and cosmonaut Alexander Samokutyaev.

The two crews will then close the three hatches leading between shuttle and station at about 7:10 a.m. EDT.

Endeavour is due to depart the space station for the twelfth and final time of her storied career on Sunday at 11:55 p.m., and then slowly travel out to a distance of about 400 feet.

Pilot Johnson will then begin flying Endeavour as he takes the orbiter on a 360-degree lap from above the space station nearly thirty minutes after undocking.

Endeavour will then perform a separation burn following the flyaround, and several minutes later will begin to test a next generation aide in navigating and docking in orbit by the future Orion spacecraft.

The Sensor Test for Orion Relative Navigation Risk Mitigation, or STORRM, can operate from three miles away to up to just five feet from the space station's docking target.

"Once we undock and separate from space station, we will re-rendezvous on a different type of profile to gather more data and be somewhat more similar to what Orion would do during a space station approach," Kelly explained several days before launch.

A second separation burn will move the spacecraft further out to a distance of about 18,000 feet before Kelly and pilot Johnson begin to reapproach the football field size complex again -- a first in the shuttle program.

Using a sensor in the shuttle's payload bay and a high-def camera tied to a laptop computer on the shuttle's flight deck, commander Kelly will guide Endeavour on a reapproach to the space station to test STORRM.

Two and one-half hours following undocking, Endeavour will begin a series of burns to close in using the advanced sensor system, while the space station is positioned for the test.

"The STORRM test will greatly enhance our knowledge of advanced laser-based navigation sensor technologies," manager Howard Hu of Orion system performance and analysis at the Johnson Space Center said. It will "provide safer and more robust rendezvous and docking capabilities for future spacecraft.”

Commander Kelly will perform the final separation burn at about 4:35 a.m. on Monday, to begin Endeavour's two day voyage home -- her final days sailing upon the ocean of space.

Endeavour is set to land at the Kennedy Space Center's shuttle landing facility's runway 15/33 on Wednesday at 2:35 a.m.