The European Space Agency is set to become the owner of what could become the most dangerous piece of space debris orbiting the Earth, officials say.

The agency will take control of the Envisat satellite, at more than 17,000 pounds the biggest non-military Earth observation satellite ever built, SPACE.com reported Tuesday.

When the Envisat mission ends in 2013, the retired satellite will become a huge "space junk" problem that will not go away for 150 years, experts say.

That is how long it will take for Envisat to be gradually pulled into the Earth's atmosphere, they predict.

In January, the upper stage of a Chinese rocket almost collided with Envisat, and ground controllers had to use the satellite's thrusters to move it out of the way.

Once Envisat is retired in three years, such maneuvers will no longer be possible, scientists say.

Had the collision happened, it would have polluted a highly populated portion of low-Earth orbit with large amounts of space debris, Heiner Klinkrad of ESA's space debris office said.