For Release: October 27, 1998

June Malone
Media Relations Office
(256) 544-7061/0034
June.Malone@msfc.nasa.gov
/centers/msfc/NEWSROOM/

RELEASE: 98-215

Key components of an experimental system that will allow spacecraft to automatically link up in orbit will be tested during the STS-95 Space Shuttle mission scheduled for launch on Oct. 29.

Until now, the exacting maneuvers of rendezvous and docking depended on human control. Astronauts and ground crews devoted considerable time to manually guiding spaceships as they approached and met in orbit. The new Automated Rendezvous and Capture technology developed by scientists at NASA's Marshall Space Flight Center in Huntsville, Ala., requires little or no ground or crew support.

"We expect this new technology will free astronauts from a repetitive task and allow them to perform space science and other human-intensive activities," said Gene Beam, the system's project manager at Marshall Center. "Onboard sensors, computers and navigation inputs from satellites will provide all the information needed to complete docking maneuvers."

The key to this new technology is the Marshall Center-developed Video Guidance Sensor. The guidance system includes a video camera and dual-frequency lasers. A satellite - the SPARTAN solar physics spacecraft - will be deployed from the Shuttle's cargo bay to serve as a laser target during the tests. It will be fitted with special reflectors. Lasers will shine on the SPARTAN, and a sensor in the Space Shuttle cargo bay will detect reflected laser light to determine the spacecraft's exact position and distance from the Shuttle.

In ground testing, the guidance system has homed in on targets with an accuracy of one-tenth of an inch. Space testing of the system will collect tracking data from a moving target under space lighting conditions and at distances ranging from 3 to 220 yards from the Shuttle. The Shuttle's robot arm will place the Spartan in multiple predetermined positions, while the Shuttle rotates, to study guidance system performance.

While the system is being tested in its automatic mode, an STS-95 crew member will operate and monitor the Video Guidance Sensor. The crew member will have primary control over the process at all times.

The Video Guidance Sensor and other Automated Rendezvous and Capture elements have been ground tested at Marshall Center's Flight Robotics Laboratory. The Video Guidance Sensor and related technologies are being developed to support the upcoming International Space Station, reusable launch vehicles and other space systems.

The STS-95 mission will mark the second time the Video Guidance System has been tested in space. The sensor's initial flight test in November 1997 did not produce all the data necessary to fully assess its performance.

Prepared by John Bryk