NASA 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. The mission is an
in-space demonstration of an autonomous rendezvous prototype
system.

NASA 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.

“The successful automation of these types of maneuvers,
demonstrated by DART technologies, will benefit future space
systems development requiring in-space assembly, services or
other autonomous rendezvous operations,” said Jim Snoddy,
DART project manager. “This milestone moves us one step
closer to a DART launch, where technologies proven on the
ground will be demonstrated in space,” he added.

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.

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.

DART and the Pegasus vehicle were developed by Orbital
Sciences Corp., Dulles, Va. NASA’s Exploration Systems
Mission Directorate, Washington, funds the DART project.

For more information about DART on the Internet, visit:

http://www.msfc.nasa.gov/news/dart/