http://www.esa.int/Our_Activities/Operations/ERS-2
ERS-2
| ROLE | Earth observation (EO) |
| LAUNCH DATE | 21 Apr 1995 |
| LAUNCHER/LOCATION | Ariane 4/Kourou, French Guiana |
| LAUNCH MASS | 2516 kg |
| ORBIT | Sun-synchronous, polar, 800 km |
| PERIOD | 100 minutes |
| NOMINAL MISSION | Complete |
| + Wind Scatterometer & GOME: first instruments of their kind + |
The mission
ERS-2 is ESA's second EO mission, (after ERS-1) and was launched in 1995.
Both carry a comprehensive payload including a Synthetic Aperture Radar (SAR) and a radar altimeter for studying sea surface temperatures and winds; ERS-2 additionally carries a sensor for atmospheric ozone research.
When they were launched, the two ERS satellites were the most sophisticated EO spacecraft ever developed and launched in Europe.
In March 2000, a computer and gyro control failure led to the end of ERS-1's mission. The ERS-2 mission has however continued to be a great success, lasting well beyond its original three year design lifetime and overcoming critical on-board problems.
In 2001, after the failure of several on-board gyro systems, an innovative new scheme for flying and controlling the ERS-2 mission without gyros was invented by a group of engineers across ESA and industry- the "gyro-less" yaw steering mode or "Zero-Gyro Mode". In 2003, a failure in the on-board data storage system led to the mission being re-designed as "real-time" only, with science data directly relayed to ground at the time of acquisition. These in-flight adaptations have enabled the mission to be extended well beyond its design lifetime, and ERS-2 had already surpassed more than 82 000 orbits at the end of 2010.