After a month of unsuccessful attempts to reestablish communications with its Earth-observing satellite, Envisat, the European Space Agency (ESA) officially declared the iconic mission over on May 9.
Launched in March 2002, the eight-ton spacecraft exceeded its intended 5-year lifetime by a factor of 2 before falling silent without warning on April 8.
Over the course of its 10-year mission, Envisat data supported than 2,500 scientific papers and 4,000 projects in over 70 countries. Loss of the craft represents a major setback to many of the ongoing projects that were dependent upon its continuous flow of observational data.
As the largest non-military satellite ever built, Envisat carried 10 sophisticated instruments that provided precise information about Earth’s land, oceans, ice caps and atmosphere and contributed to our understanding of climate change.
Envisat: 10th Anniversary Video
The video above, commemorating Envisat’s 10 years of service, was released prior to loss of communication on April 8, 2012. At the time, ESA planned to keep the aging satellite operational until launch of the Sentinel missions in 2013.
Envisat documented the gradual shrinking of Arctic sea ice and the regular opening of the polar shipping routes during summer months. Together with other satellites, it monitored global sea-level height and regional variations, as well as global sea-surface temperatures with a precision of a few tenths of a degree. Years of Envisat data also led to a better understanding of ocean currents and chlorophyll concentrations.
In the atmosphere, the satellite observed air pollution increase in Asia and its stability in Europe and North America. It measured carbon dioxide and methane concentrations and also monitored variations in the Antarctica ozone hole.
Over land, it mapped the speed of ice streams in Antarctica and Greenland. Its images were used regularly to update the global maps of land use, including the effects of deforestation.
Using its imaging radar, Envisat mapped ground displacements triggered by earthquakes and volcanic eruptions, improving understanding of tectonics and volcanic mechanisms.
In addition to providing scientific data, Envisat also monitored floods and oil spills, helping civil authorities to manage natural and man-made disasters.
Where possible, Envisat’s most critical data-gathering responsibilities are being shifted to other satellites, but loss of the craft only highlights the need for ESA to meet its often-delayed schedule for launching the next generation of earth-observing satellites known as Sentinals 1-5. The first of those missions is now scheduled for 2013.
Optical, radar and laser observations of Envisat during the past month indicate that it continues to circle the Earth in a stable, near-polar orbit. Given its mass and altitude, and left to its own devices, the satellite appears destined to become the largest piece of orbital space-junk before falling to Earth in about 150 years.
