DART

Launch data: Designation  28642 / 05014A Launch date  15 Apr 2005 - 17:26 UT Launch site  Va, L-1011 Launch vehicle  Pegasus-XL/HAPS Mission  Technology, automatic rendezvous Earth orbit on 16 Apr - 05:45 UT: Perigee / Apogee  741 x 751 km Inclination  97.73° Period  99.74 min

DART (right) approching target

Mission details:

• DART will prove the technologies required for spacecraft to locate and rendezvous with another spacecraft without direct human guidance. While NASA has performed rendezvous and docking missions in the past, astronauts have always piloted the spacecraft. The autonomous rendezvous technologies demonstrated by DART represent a critical step for establishing an autonomous rendezvous capability for the United States and will lay the groundwork for future reusable manned and unmanned launch vehicle operations. Future applications of this technology include cargo delivery, space operations for the International Space Station (ISS) and other on-orbit activities such as satellite retrieval and servicing missions.
• The auxiliary propulsion system includes three hydrazine-fueled thrusters delivering 150 pounds of force. The Pegasus reaction control system includes six nitrogen-fueled thrusters producing 150 pounds of force. DART also uses 16 proximity operations reaction control engines propelled by nitrogen that offer 13 pounds of thrust. The vehicle will then perform a series of orbit transfers to arrive at a point near a target satellite using state-of-the-art GPS relative navigation techniques. Using the vehicle's main instrument, the Advanced Video Guidance Sensor (AVGS), DART will then approach the target satellite, MUBLCOM launched on 18 May 1999, and perform a series of proximity operations including station keeping, docking axis approaches and circumnavigation. Finally the vehicle will demonstrate a collision avoidance maneuver then depart the vicinity and transition to its final orbit. The entire sequence will be accomplished under autonomous control.
• DART  was successfully launched 15. April 2005 at 10:25 a.m. PDT from Vandenberg Air Force Base, Calif., but experienced an on orbit anomaly late that day. After a successful rendezvous, acquisition of the target spacecraft, and approach to within approximately 300 feet, DART placed itself in the retirement phase before completing all planned proximity operations, ending the mission prematurely.
• The satellite performed a rendezvous with the MUBLCOM satellite (99026B) approximately April 26.17 and it was planned that DART would perform station-keeping manoeuvres with the target satellite. It is believed that DART approached MUBLCOM within 100 metres but was found to be running short of propellant: it therefore retreated and the mission ended with perigee being reduced. It has been reported that DART made umplanned contact with MUBLCOM. The orbit of MUBLCOM at the time of the rendezvous was as follows: April 16.17 97.72° 99.69 minutes 740 x 747 km. After the DART mission ended, the orbit of MUBLCOM was slightly changed: April 19.78 97.72° 99.74 minutes 741 x 751 km. After the station-keeping mission was terminated, DARTmanoeuvred to a 395-747 km orbit.
• NASA officials have confirmed that the DART rendezvous spacecraft bumped into its target satellite 760 kilometers above the Earth during then redezvous maneuver. The DART spacecraft did make contact with the target satellite during the rendezvous phase of the mission and boosted it into a slightly higher orbit. Neither DART (Demonstration of Autonomous Rendezvous Technology) nor its target satellite MUBLCOM appeared to have been damaged in the incident.

External links:

• EOportal.org Satellite description