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NASA Headquarters, Washington, Oct. 1/Satnews Daily/
— NASA said it is planning to launch the Demonstration of Autonomous Rendezvous
Technology (DART) flight demonstrator in late October. The launch is planned no
earlier than Oct. 26 from Vandenberg Air Force Base, Calif.
DART will be carried into space aboard a Pegasus rocket.
The Pegasus rocket will be launched from a Stargazer L-1011 jet aircraft at
approximately 40,000 feet over the Pacific Ocean. The Pegasus will boost DART
into an approximately 471-by-479-mile polar orbit.
DART will travel around the Earth to rendezvous with the Multiple Paths,
Beyond-Line-of-Site Communications experimental satellite. The target satellite
was designed for use with a video guidance system like the Advanced Video
Guidance Sensor on DART.
DART and the Pegasus vehicle were developed by Orbital
Sciences Corp., Dulles, Va. NASA's Exploration Systems Mission Directorate,
Washington, funds the DART project.
NASA said it has successfully ground tested technologies
that will enable unmanned spacecraft to rendezvous autonomously, something never
done before in the history of U.S. spaceflight. The ground tests were performed
at the Flight Robotics Laboratory at NASA's Marshall Space Flight Center,
Huntsville, Ala.
The tests demonstrated the capability of hardware and software to communicate
with each other and to drive the spacecraft autonomously to achieve a safe,
assured rendezvous and close approach to a target.
Video guidance sensor and autonomous rendezvous guidance technologies have
performed flawlessly, according to NASA managers. The tests verified critical
autonomous rendezvous technologies, including the ability of the Advanced Video
Guidance Sensor to combine with other technologies, such as the Global
Positioning System and Automated Rendezvous and Proximity Operations
calculations.
The video guidance sensor sees and determines a spacecraft's exact location,
then feeds the information to Automated Rendezvous and Proximity Operations
calculations, or algorithms, that function as a brain. The brain commands the
spacecraft to turn, throttle, or brake, allowing it to rendezvous with another
craft.
The tests were performed using mock-ups of the DART spacecraft and target
satellite, demonstrating successful proximity operations with video guidance
sensors for target location. DART navigation guidance transitioned successfully
from the Global Positioning System to direct use of the video guidance
information. The DART spacecraft then moved progressively closer to the target
satellite under direct video guidance.
A number of maneuvers were demonstrated in the simulated ground tests, including
collision avoidance, horizontal approaches toward the target satellite,
transition to docking guidance, and docking-hold to within five meters of the
target.
While on orbit, DART will perform several close proximity operations, such as
moving toward and away from the target satellite using navigation data provided
by onboard sensors. DART will also test additional algorithms by calculating and
executing collision avoidance maneuvers and will travel around the target. To
conclude the mission, DART will fly away from the satellite. The entire 24-hour
mission will be accomplished without human intervention.
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