Demonstration For Autonomous Rendezvous Technology
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DART, or Demonstration for Autonomous Rendezvous Technology, was a
NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
spacecraft with the goal to develop and demonstrate an automated navigation and rendezvous capability. At the time of the DART mission, only the
Roscosmos The State Corporation for Space Activities "Roscosmos", commonly known simply as Roscosmos (), is a State corporation (Russia), state corporation of the Russian Federation responsible for space science, space flights, List of space agencies, c ...
and
JAXA The is the Japanese national air and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satellites into o ...
had autonomous spacecraft navigation.
Orbital Sciences Corporation Orbital Sciences Corporation (commonly referred to as Orbital) was an American company specializing in the design, manufacture, and launch of small- and medium- class space and launch vehicle systems for commercial, military and other governmen ...
(OSC) was the prime contractor for construction, launch and operation of the DART spacecraft with a project cost of US$110 million (2005). The contract was awarded in June 2001 and the spacecraft was launched on 15 April 2005. The mission ended prematurely, very shortly after an anomalous slow-velocity collision with its target spacecraft, having completed less than half of the original mission autonomous rendezvous objectives.


Mission

DART was launched on a
Pegasus rocket Pegasus is an Air launch to orbit, air-launched launch vehicle, multistage rocket developed by Orbital Sciences Corporation (OSC) and later built and launched by Northrop Grumman. Pegasus is the world's first privately developed orbital laun ...
into a
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of and has International Designator 2005-014A. The craft is and weighs . The maneuvering system comprised 16
nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...
-fueled thrusters with three
hydrazine Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly hazardous unless handled in solution as, for example, hydraz ...
-fueled thrusters and a
reaction control system A reaction control system (RCS) is a spacecraft system that uses Thrusters (spacecraft), thrusters to provide Spacecraft attitude control, attitude control and translation (physics), translation. Alternatively, reaction wheels can be used for at ...
including six nitrogen-fueled thrusters from the Pegasus fourth stage, which forms an integral part of the spacecraft. The target spacecraft was an OSC MUBLCOM (Multiple-Path Beyond-Line-of-Sight Communications) prototype communications relay satellite weighing approximately launched from
Vandenberg Air Force Base Vandenberg may refer to: * Vandenberg (surname), including a list of people with the name * USNS ''General Hoyt S. Vandenberg'' (T-AGM-10), transport ship in the United States Navy, sank as an artificial reef in Key West, Florida * Vandenberg S ...
on 18 May 1999 with International Designator 1999-026B. After launch, DART successfully achieved orbit and within hours made a rendezvous with the target satellite. The automated systems aboard DART successfully acquired the target and began autonomously approaching it. During proximity operations, multiple malfunctions in navigation, propellant management and collision avoidance programming led to a soft collision with the target and premature destruction and retirement of the DART spacecraft. DART had no capability for interactive piloting from the ground or for uploading new programming after launch, thus all on-orbit operations were directed by DART itself based upon pre-programmed criteria.


Objectives


Automatic orbital transfer maneuvers

The craft autonomously navigated via a series of orbit transfer maneuvers to reach the target satellite. No navigational information was relayed to the vehicle after launch; it navigated autonomously and with
GPS The Global Positioning System (GPS) is a satellite-based hyperbolic navigation system owned by the United States Space Force and operated by Mission Delta 31. It is one of the global navigation satellite systems (GNSS) that provide geol ...
.


Proximity operations with AVGS

Once the spacecraft had navigated to the target satellite, it was to have performed a series of proximity maneuvers. The maneuvers would have demonstrated the capabilities of the AVGS (Advanced Video Guidance Sensor). It was planned to demonstrate station keeping, docking axis approach, circumnavigation, and a collision avoidance maneuver. DART would have then departed the vicinity and retired to a final orbit. The entire sequence was to have been accomplished under autonomous control.


Additional demonstrations

* Validate ground test results of the AVGS and proximity-operations algorithms * Provide hardware capabilities for future missions by validating the AVGS in the space environment


Mishap investigation board

NASA convened a mishap investigation board to determine the reason for the DART spacecraft anomaly. First reports pointed to the spacecraft running out of fuel before concluding its mission. On 14 April 2006, NASA announced that they would not release the investigation's report, citing that the report includes details protected by the
International Traffic in Arms Regulations International Traffic in Arms Regulations (ITAR) is a set of U.S. Department of State regulations that control the export of defense and military technologies to safeguard national security and further its foreign policy objectives. Overvi ...
(ITAR). On 15 May 2006, NASA released a public summary of the DART mishap investigation board report. NASA revealed that a critical navigation failure occurred when the DART and MUBLCOM spacecraft were about 200 meters apart, which precluded the full activation of the AVGS and allowed DART to approach MUBLCOM without accurate ranging information. A later failure of the collision avoidance system, which was relying upon inaccurate position and velocity information, allowed DART to ultimately collide with MUBLCOM at a relative speed of approximately 1.5 meters per second. Both spacecraft survived the collision without apparent damage. Throughout the autonomous proximity operations, DART used its limited propellant faster than anticipated, which caused "a premature end to the mission" 3 minutes 49 seconds after the collision. DART initiated its retirement programming, removed itself from the vicinity of MUBLCOM, and prepared for deorbit. After the collision, MUBLCOM "regained its operational status after an automatic system reset". The DART Mishap Investigation Board determined that only 11 of the 27 defined mission objectives were partially or fully met, all of which related to the launch, early orbit, rendezvous, departure, and retirement phases. None of the 14 objectives related to the proximity operations phase were met.


Atmospheric entry

DART re-entered in the
atmosphere of Earth The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weather ...
around 08:32
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on 7 May 2016 over the
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.


See also

*
Attitude control Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle or satellite) with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, ...
*
Orbital Express Orbital Express: ASTRO and NEXTSat Orbital Express was a space mission managed by the United States Defense Advanced Research Projects Agency (DARPA) and a team led by engineers at NASA's Marshall Space Flight Center (MSFC). The Orbital Express p ...
*
Spacecraft A spacecraft is a vehicle that is designed spaceflight, to fly and operate in outer space. Spacecraft are used for a variety of purposes, including Telecommunications, communications, Earth observation satellite, Earth observation, Weather s ...


References


External links


DART at Marshall Space Flight Center


16 April 2005
Mishap overview and description of the cause
15 May 2006
DART Mishap Investigation Board Final Report
4 January 2007
NASA DART press kit
April 2015 {{Orbital launches in 2005 NASA satellites Derelict satellites orbiting Earth Spacecraft launched in 2005 Satellite collisions Spacecraft launched by Pegasus rockets