content long 20-May-2013 00:32:50

Orbit/Navigation

Self Propelled

Once released the two satellites used their own on-board propulsion systems to reach the final operational orbit. This involved changing their orbital inclination from 64.8° to 90°, while raising the highest point above the Earth (apogee) to 119 000 kilometres and the lowest point (perigee) of 19 000 kilometres.

Separation and orbit manoeuvres for Fregat and the Cluster pair

Projection of Cluster pair on operational orbit plane

To do this, each Cluster II spacecraft main engine performed six major manoeuvres. These orbital changes are made possible by the large amount of on-board fuel and oxidiser (245 kg MMH* + 405 kg NTO* = 650 kg), which makes up approximately half of each satellite's launch mass (1200 kg).

This nominal orbit is essentially inertially fixed, so that in the course of the mission it will enable a detailed examination of all significant regions of the Earth's magnetosphere.

Graphics showing the distance of the upper spacecraft (left) and lower spacecraft (right) from the Earth over the 7 days from injection in circular orbit.

* NTO = N2O4 = nitrogen tetroxide
   MMH = monomethylhydrazine

Last Update: 27 April 2010

For further information please contact: SciTech.editorial@esa.int

Related Articles

  • Soyuz-Fregat Orbit (http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=33312&fbodylongid=1192)
  • Self Propelled (http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=33312&fbodylongid=1193)
  • Final Orbit (http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=33312&fbodylongid=1194)

Related Links

  • Satellite Situation Centre (http://sscweb.gsfc.nasa.gov/)
  • Cluster Orbit Visualisation Tool (http://ovt.irfu.se/)
  • Current Cluster Position (http://www.cluster.rl.ac.uk/pub-query/quicklook?Par=sc_r_xyz_gse__CL_JP_PGP:CL_JP_PGP)