Orbital Express

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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 program was aimed at developing "a safe and cost-effective approach to autonomously service satellites in orbit."[1] The system consisted of two spacecraft: the ASTRO servicing satellite, and a prototype modular next-generation serviceable satellite; NEXTSat. The mission launched from Cape Canaveral Air Force Station on March 8, 2007, aboard an Atlas V expendable launch vehicle.[2][3] The launch was part of the United States Air Force Space Test Program STP-1 mission.[4]

Program management and contractors[edit]

The Orbital Express program was managed by the Tactical Technology Office (TTO), one of the six technical offices in DARPA.[5] TTO programs included both "Aerospace Systems" such as Orbital Express, and "Tactical Multipliers" such as the "Magneto Hydrodynamic Explosive Munition (MAHEM) program".[6] ASTRO was developed by Boeing Integrated Defense Systems, and NEXTSat was developed by Ball Aerospace & Technologies Corp.. NASA's involvement was through the Automated Systems and Automated Rendezvous and Docking Division of the Engineering Directorate at MSFC. The MSFC Engineering Directorate also managed the Advanced Video Guidance System (AVGS) for Orbital Express project.[7] The refueling mechanism was designed, developed and produced by VACCO Industries.


Orbital Express: ASTRO and NEXTSat

The project hoped to demonstrate several satellite servicing operations and technologies including rendezvous, proximity operations and station keeping, capture, docking, fluid transfer (specifically, hydrazine on this mission), and ORU (Orbit Replaceable Unit) transfer. A prime military mission would be to refuel reconnaissance satellites so they can improve coverage, increase surprise and be more survivable.[8]

The fluid (fuel) and ORU (battery) transfers were completed successfully at the lowest levels of spacecraft autonomy. Subsequent transfers over a three-month period were intended to demonstrate greater autonomy.[9][dated info]

End of mission[edit]

The final rendezvous and docking between the two spacecraft occurred on 29 June 2007. This was followed by the final demonstration, the changeout of a flight computer aboard ASTRO. NASA's plans for an extended mission were abandoned. The two craft demated for a final time, with ASTRO backing out to greater than 400 km (250 mi)[10] in a test of sensor performance. Following this the craft performed a rendezvous to a standoff, where decommissioning took place.[11] The NEXTSat spacecraft was deactivated on 21 July, when its computers were turned off, and solar panels pointed away from the Sun. Subsequently, ASTRO vented its Hydrazine propellant, and was deactivated on 22 July 2007. The satellites were left to decay naturally.[12]

NextSat was expected to take three to five years to decay, while the heavier ASTRO satellite was expected to take fifteen years.[12] However, ASTRO reentered the atmosphere on 25 October 2013.[citation needed]

See also[edit]


1. http://www.boeing.com/bds/phantom_works/orbital.html

External links[edit]