Envisat Satellite Failure

The European Space Agency declared the Envisat satellite failure on May 9 after a month of mysterious silence from the school bus-size spacecraft.

Envisat is the world’s largest Earth-watching satellite for civilian use, with ESA officials touting its 10th anniversary in space earlier this year. The $2.9 billion satellite was originally designed to snap high-resolution photos of Earth for five years, but managed to last 10 years during its successful mission. The troubles for Envisat began April 8, when the satellite abruptly stopped communicating with ground stations. There are several possible explanations for Envisat’s unexpected demise. ESA officials said the failure of a power regulator may be blocking the satellite’s telemetry and telecommand systems. There may have also been a short circuit on board that plunged Envisat into a protective “safe mode,” then a second malfunction that left the satellite in an unknown state, incapable of receiving commands from Earth. Although chances of recovering Envisat are extremely low, the investigation team will continue attempts to re-establish contact while considering failure scenarios for the next two months. Envisat is by all accounts a huge satellite. It is about 30 feet long (9 meters) and 16 feet wide (5 m). The spacecraft weighs 17,600 pounds (8,000 kilograms) and has a huge sail-like solar array that is 16 feet wide (5 m) and 46 feet long (14 m). ESA launched the Envisat mission in 2001 to study the Earth from space in extreme detail.
source:www.space.com