ESA officials immediately declared a spacecraft emergency once contact was lost and began listening for any transmissions from the silent spacecraft, but so far Envisat has been mum. The satellite, however, is not falling out of space.
"While it is known that Envisat remains in a stable orbit around Earth, efforts to resume contact with the satellite have, so far, not been successful," ESA officials said in a statement released Thursday (April 12).
Envisat orbits the Earth at an altitude of about 486 miles (782 kilometers). It completes one trip around the planet every 100 minutes and has completed more than 50,000 orbits since its launch in 2002.
The $2.9 billion satellite is one of the most expensive ever built and the largest non-military satellite to observe the Earth from orbit. It is about 30 feet long (10 meters) and 16 feet wide (5 m), with a huge solar array that is about 16 feet wide (5 m) and 46 feet long (14 m), according to an ESA description.
In 2010, orbital debris experts said that the sheer size of the satellite makes Envisat a major space junk concern once its mission ends. At the time, scientists said the satellite would likely stay in orbit for about 150 years, barring unforeseen circumstances. However, it is still too early to know if Envisat is permanently lost or can be recovered in the coming days.