Mission Extension Vehicle
The Mission Extension Vehicle (MEV) is a spacecraft concept proposed by ViviSat, a 50/50 joint venture of aerospace firms U.S. Space and ATK, to operate as a small-scale in-space satellite-refueling spacecraft.
Technical capabilities and competition 
ViviSat will compete for space servicing business with the recently announced Space Infrastructure Servicing (SIS) vehicle from MDA. However, the two vehicles will operate with different technology approaches. ViviSat will connect to the target satellite in the same way as MDA SIS, but will not transfer fuel. It will rather use "its own thrusters to supply attitude control for the target."
In a June 2012 article in The Space Review, a number of approaches to satellite servicing were discussed. ViviSat's Mission Extension Vehicle is reported to operate at the "less complex" end of the technology spectrum, which could offer higher reliability and reduced risk to satellite owners.
ViviSat believes their approach is more simple and can operate at lower cost than MDA, while having the technical ability to dock with "90% of the 450 or so geostationary satellites in orbit," whereas MDA SIS can dock to only 75%.
"In addition to extending the life of an out-of-fuel satellite, the company could also rescue fueled spacecraft like AEHF-1 by docking with it in its low orbit, using its own motor and fuel to place it in the right orbit, and then moving to another target."
By March 2012, ViviSat was finalizing it's design and was "ready to build" the servicing spacecraft, but as of June 2012[update], ViviSat has announced no customers for the Mission Extension Vehicle services.
See also 
- Orbital Express — a 2007 U.S. government-sponsored mission to test in-space satellite servicing technologies with two vehicles designed from the start for on-orbit refueling and subsystem replacement.
- Propellant depot
- "ViviSat Corporate Overview". company website. ViviSat. 2009. Retrieved 2011-08-26.
- Morring, Frank, Jr. (2011-03-22). "An End To Space Trash?". Aviation Week. Retrieved 2011-03-21. "ViviSat, a new 50-50 joint venture of U.S. Space and ATK, is marketing a satellite-refueling spacecraft that connects to a target spacecraft using the same probe-in-the-kick-motor approach as MDA, but does not transfer its fuel. Instead, the vehicle becomes a new fuel tank, using its own thrusters to supply attitude control for the target. ... [the ViviSat] concept is not as far along as MDA."
- Foust, Jeff (2012-06-25). "The space industry grapples with satellite servicing". Space Review. Retrieved 2012-07-04.
- de Selding, Peter B. (2011-03-18). "Intelsat Signs Up for MDA’s Satellite Refueling Service". Space News. Retrieved 2011-03-20. "more than 40 different types of fueling systems ... SIS will be carrying enough tools to open 75 percent of the fueling systems aboard satellites now in geostationary orbit. ... the SIS spacecraft is designed to operate for seven years in orbit but that it is likely to be able to operate far longer than that. Key to the business model is MDA’s ability to launch replacement fuel canisters that would be grappled by SIS and used to refuel dozens of satellites over a period of years. These canisters would be much lighter than the SIS vehicle and thus much less expensive to launch. "
- "ATK: Introducing the expanded product line of agile spacecraft buses". Space News. 2012-08-13. p. 16-17. "ATK A100 THEMIS; ATK A200 ORS-1, TacSat3, and EO-1; ATK A500 DARPA Phoenix; ATK A700 ViviSat"
- U.S. Space official website
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