Mission Extension Vehicle

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The Mission Extension Vehicle ( MEV ) is a retrofittable drive for geostationary satellites whose fuel supply is running low. It is the first unmanned on-orbit servicing system that is ready for use after several decades of research and development in this field. The MEV was invented in the 2000s by employees of the US industrial group Alliant Techsystems (ATK). After various company takeovers, it is now manufactured and sold by the Northrop-Grumman subsidiary Space Logistics LLC .

history

According to a space logistics manager, the idea for such a satellite maintenance system arose at ATK in the mid-2000s. In 2009, the company began developing the MEV. To commercialize the project, the joint venture Vivispace was founded in 2011 with the satellite communications provider US Space ; US Space was responsible for marketing and mission management.

Through a merger with Orbital Sciences Corporation in 2015, ATK's space division gained a financially strong new partner who pushed the MEV project. ATK then broke the cooperation with US Space: Despite protests and finally legal action by US Space, a contractual clause was activated - with success - according to which the project would fall entirely to ATK or the newly created Orbital ATK if certain marketing goals were not achieved . The latter was later taken over by Northrop Grumman and renamed Northrop Grumman Innovation Systems (since 2020: Northrop Grumman Space Systems).

In 2016, the planning of a first mission began under the mission name MEV-1 . Soon afterwards, Intelsat was won as a customer with the Intelsat 901 television satellite . Intelsat 901 went into operation in 2001 and had already exceeded its planned lifespan of 13 years. With the MEV as the new drive, the satellite should be usable for at least another five years. The propulsion vehicle was launched from the Baikonur Cosmodrome on October 9-10, 2019 with a Proton / Bris-M rocket . A new Eutelsat communications satellite was also on board the same flight so the launch costs could be shared. On February 25, 2020, the MEV successfully docked with Intelsat 901, and in April 2020 the two together reached their planned new geostationary position at 27.5 ° West.

Intelsat ordered a second Mission Extension Vehicle back in 2018. It was launched on August 15, 2020 with an Ariane 5 from the Guiana Space Center under the mission name MEV-2 , along with two communication satellites.

functionality

The service life of satellites is limited by the aging and wear and tear of the technical systems. Often, however, the mission ends (as planned) by using up the fuel carried, which is used for attitude control and orbit maneuvers , while the payload is still functional. In this case, the MEV is intended to extend the service life of the satellite. For this purpose, it is brought into orbit with a launch vehicle and from there flies to the satellite, on which it docks permanently . From now on it replaces its internal drive.

Docking is proceeding according to plan as follows: The MEV is launched into a geostationary transfer orbit - a highly elliptical orbit with a perigee height of a few hundred and an apogee height of around 36,000 kilometers. With its own drive it gradually raises the perigee until a circular geostationary orbit is reached after three and a half months. The target satellite also raises its orbit a little; both approach each other at an altitude of 36,100 km, slightly above the geostationary area and thus at a safe distance from the other satellites present there. The further approach takes place in stages, as the MEV controls so-called hold points 80, 20 and one meter away from the satellite. It pauses there until it is checked and confirmed that the approach is going according to plan. Finally, the vehicle extends a docking arm and retracts the satellite's engine nozzle . The arm grips the engine from the inside and is then retracted again until both spacecraft are firmly connected. With the new drive, the satellite moves back to a geostationary position and is back in operation.

80% of the geosynchronous communication satellites in use today have an engine whose mechanical structure is compatible with the MEV coupling system.

technical structure

The Mission Extension Vehicle based on the GeoStar-3 - satellite bus by Orbital Sciences, that is, even it has the form of a satellite. As the main drive, it uses efficient ion thrusters with the noble gas xenon as a supporting mass . One speaks of an "electric drive" because the gas is ionized by an electric current; Photovoltaic modules serve as the voltage source .

Since an ion drive generates only a small amount of thrust , an additional conventional drive with hydrazine as fuel is available , especially for the coupling maneuver, which requires fast reactions . Cameras and a lidar system are used to monitor the approach .

Missions

Status: August 14, 2020

All dates refer to Coordinated Universal Time (UTC).

mission satellite Satellite launch MEV start Coupling time status
MEV-1 Intelsat 901 June 9, 2001 October 9, 2019 February 25, 2020 in operation
MEV-2 Intelsat 10-02 June 16, 2004 15th August 2020 on road

Web links

Individual evidence

  1. ↑ a b c d Stephen Clark: Satellite industry's first robotic servicing mission ready for launch. In: Spaceflight Now. October 8, 2019, accessed October 9, 2019 .
  2. ↑ a b c d e Chris Gebhardt: Proton rocket ride-share to launch Northrop Grumman's Mission Extension Vehicle. In: Nasaspaceflight.com. October 8, 2019, accessed October 9, 2019 .
  3. ↑ ViviSat Launched - New Venture Will Provide Satellite Life Extension Services. In: Spaceref. Vivisat, January 13, 2011, accessed October 9, 2019 .
  4. ↑ Vivisat's historical website in the Internet Archive , as of January 2018.
  5. ↑ US Space sues Orbital ATK over ViviSat venture . Spacenews, May 3, 2016.
  6. ↑ Arianespace press material on the launch of Intelsat 901 (Ariane flight 141) (PDF; 1 MB).
  7. ↑ Intelsat 901 / 37e at 18.0 ° W at LyngSat, accessed on October 9, 2019.
  8. ↑ Stephen Clark: Live coverage: Proton rocket launches with two US-built satellites. In: Spaceflight Now. October 9, 2019, accessed October 10, 2019 . with video 1:21:30 ("1:28:15") EUTELSAT 5 West B / MEV-1 , IMG / International Launch Services ; about production and start, as well as animations of the planned paths of the two missions
  9. ↑ Caleb Henry: Northrop Grumman's MEV-1 servicer docks with Intelsat satellite. In: Spacenews. February 26, 2020, accessed February 27, 2020 .
  10. ^ Eric Berger: For the first time, a spacecraft has returned an aging satellite to service . Ars Technica, April 17, 2020.
  11. ↑ BSat 4b & Galaxy 30, MEV-2. In: nextspaceflight.com. Retrieved on August 16, 2020 .
  12. ↑ Triple mission success for Ariane 5: the Galaxy 30, MEV-2 and BSAT-4b satellites reach geostationary transfer orbit. In: arianespace.com. August 15, 2020, accessed on August 16, 2020 .