5,000-pound satellite crashes through atmosphere between Alaska and Hawaii

A satellite made an uncontrolled return to Earth Wednesday, re-entering the atmosphere over the north Pacific Ocean between Alaska and Hawaii, according to the the European Space Agency. 

The agency said ERS-2, which weighs about as much as an adult male rhinoceros, crashed through the atmosphere at 5:17 p.m. UTC. The agency was unable to predict exactly when and where the satellite would re-enter because its return was "natural."

What is a natural return?

ERS-2's batteries were depleted and its communication antenna and onboard electronics were switched off, which meant there was no way to actively control the motion of the satellite from the ground during its descent, the European Space Agency said. The last of ERS-2's fuel was used up back in 2011 to minimize the risk of a catastrophic explosion capable of generating a large amount of space debris. 

Is there any danger as ERS-2 returns?

Most of the satellite burned up as it re-entered Earth's atmosphere. None of the fragments will contain any toxic or radioactive substances.

The space agency has not yet said how many pieces of the satellite survived the return, but noted any pieces would be "spread out somewhat randomly over a ground track on average hundreds of kilometers long and a few tens of kilometers wide."

The space agency added that the annual risk of a person being injured by space debris is under 1 in 100 billion, or 65,000 times lower than the risk of being struck by lightning.

What was ERS-2 doing in space?

The satellite was launched on April 21, 1995, as an Earth observation spacecraft. It was used to collect data on Earth's land surfaces, oceans and polar caps. ERS-2 was also used to monitor natural disasters, such as severe flooding and earthquakes.  

Its mission ended in 2011, when the European Space Agency began deorbiting the satellite. The deorbiting process helps prevent collisions in orbit and mitigates the creation of space debris. 

ERS-2's remaining fuel was used up as it was deorbited. The satellite's average altitude was also lowered.