NASA's Earth Radiation Budget Satellite to fall to Earth after 38 years in space

A NASA satellite is expected to fall to Earth this weekend after nearly 40 years in space.

The Earth Radiation Budget Satellite (ERBS) was launched in 1984 aboard the space shuttle Challenger.

It was initially sent into space with a lifespan of just two years to study how the Earth absorbed and radiated energy from the sun.

But the satellite continued to make ozone and other atmospheric measurements until its retirement in 2005.

Now the 2,450kg object is set to crash back down to Earth.

Most of the satellite will burn up upon re-entry, according to NASA, but some pieces are expected to survive.

NASA said the chance of wreckage falling on anybody is "very low" - putting the odds of injury from falling debris to anyone on Earth at about one-in-9,400.

But the chance of the debris injuring one individual is almost unthinkably higher, given the Earth's estimated 7.8 billion population.

The satellite is expected to come down on Sunday night, give or take 17 hours, according to the US Defence Department.

The California-based Aerospace Corporation, however, is targeting Monday morning, give or take 13 hours.

The satellite is expected to pas over Africa, Asia, the Middle East and the westernmost areas of North and South America.

The ERBS was realeased into orbit by America's first woman in space, Sally Ride, using Challenger's robot arm.

It was the second and final spaceflight for Ms Ride, who died in 2012.

That same mission also featured the first spacewalk by a US woman, Kathryn Sullivan.