July 8, 2016

Mission Constraints

Long duration for central programme: 150 days

  • The line of sight is assigned to keep a constant direction for 150 days.
  • 90% duty cycle requirement (no occultation by the Earth).

Inertial polar circular orbit between 800 and 900 km

  • Lower limit fixed by terrestrial stray light.
  • Upper limit fixed by the size of the South Atlantic Anomaly and the flux of protons acceptable by the instrument.

Sun blinding

  • Sun at more than 90° of the boresight.

Semi major axisa = 7274 km
Eccentricitye = 0.00127°
Inclinationi = 90°
Right Ascension of the Ascending node RAAN = 12.5°
Boresight at 6h50 ± 12h

Straylight from the Earth

  • line of sight at more than = 20° from the Earth limb.
  • radius of the observation cone: = arccos(R/a) - = 10°
  • to be adjusted in flight after effective stray light measurements.


Roll domain

  • ±20° on the line of sight, after North-South alignment of the solar arrays.
  • Helpful to optimize the projection of the targets onto the CCD.