ERS-1 Experimental Roll Tilt Mode Campaign
Objectives
During the Experimental roll tilt mode campaign, the satellite body was rotated by 9.5 degrees allowing operation of the SAR imaging mode at an incidence angle of 35 degrees. The attitude control system performances of the roll tilt mode are not significantly different from the YSM, with the same angular rates and harmonic and random errors and only slightly different static errors, i.e. about 0.05 degrees of maximum difference. During the roll tilt sequence the satellite is in a Fine Pointing Mode (FPM), which features no yaw steering and Earth centroid pointing, rather than geometric pointing.
For this operational mode there are some constraints. Some of them are summarized hereafter; they show that this mode cannot be used regularly over the mission but rather
for a limited number of experimental campaigns.
- Roll-tilt phase can be performed only in the zone between 70 to 35 degrees N LAT.
- Performance of the RA Altimeter is slighltly degraded because of the geocentric pointing instead of the local normal pointing.
- Windscatteromer cannot be operated as it requires YSM.
Roll Tilt Mode parameters
Roll Tilt Mode parameters
- 35 day repeat cycle
- 501 orbits in one cycle
- 166 orbits in phase
Orbit number characteristics
- First absolute orbit number is: 3735 on 2-apr-92 at 15:58:35.359 UTC
- First internal track: 83
- End of the phase: orbit 3901 on 14-apr-92 06:17:59.431 UTC.
Orbit parameters
- orbit eccentricity: 0.001165
- orbit inclination: 98.5429 deg
- asc. node Long.: 97.8581 deg
- semi-major axis: 7159495.65 m
- mean nodal period: 6035.928143 s
- mean anomaly: 270.1334 deg
This information was retrieved from ESA/ESRIN
