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 at more than 90° of the boresight.
|Semi major axis||a = 7274 km|
|Eccentricity||e = 0.00127°|
|Inclination||i = 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.
- ±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.