ERS-1 Orbits

ERS-1 Orbit. Credits Heavens Above.


To carry out its mission ERS-1's orbit had to enable its instruments to scan along predetermined paths designed to give optimum coverage for a set number of orbits. To achieve this, ERS-1 was a three-axis-stabilised, Earth-pointing satellite in yaw steering mode (YSM). The elliptical orbit was sun-synchronous, near-polar, with a mean altitude of 785 km, an inclination of 98.5° and a local solar time at the descending node of 10:30 a.m.

Orbit parameters

for the 35-day orbit

Main characteristics
Semi-major axis 7159.5 km
Eccentricity 0.0001042
Argument of perigee 92.4836°
Inclination (sun-synchronous) 98.543°
Auxiliary data
Mean altitude 782 km
Nodal period 50 min 25.5 s
Repeat cycle 35 days
Number of passes per cycle 1002
Ground track separation at Equator 80 km
Orbital velocity 7.45 km/s

For the other repeat periods:

3-day 35-day 168-day
semi major axis 7153.138 7159.496 7147.191
inclination(°) 98.516 98.543 98.491
mean altitude (km) 785 782 770
orbits per cycle 43 501 2411

Further information on ERS (Esa website).