You might remember the intrepid adventure of Progress 59, the Russian spacecraft that was scheduled to send cargo and supplies to the International Space Station (ISS). After an uneventful liftoff on April 29th, 2015, the spacecraft separated from its boosters and all contact with the vessel was lost. Then it began to spin wildly out of control. Fortunately, there were no crew members on board because Progress 59 was doomed from that moment to zoom around Earth, uncontrolled and constantly losing height. It's sorry fate: to crash back down to Earth.

Progress 59 is scheduled to make one final orbit around Earth before re-entering the atmosphere tomorrow (May 8th, 2015). Many different calculations of the re-entry time and location have been estimated based on the satellite's orbit. However, there are lots of factors that haven't been taken into consideration, so no one can say with certainty the precise location or time of re-entry. However, the Russian space agency, Roscosmos, predicted re-entry will occur in a nearly 21-hour window centered on 08:39 GMT (4:39 a.m. EDT) Friday.

Video of the ISS Progress 59 cargo craft spinning via NASA

So the question that's on the tip of everyone's tongue is: what happened? Why did Progress break down? Our inability to communicate with Progress 59 makes it difficult to know, but there are plenty of speculations.

A sudden, unexpected release of gas or an explosion on the Progress could have caused it to start spinning. Forty four pieces of debris have been found to be associated with the Progress shuttle; the quantity could be suggestive of an explosion.

Objects drop out of the sky into Earth's atmosphere every day. However, it's unusual for one of these tumbling objects to have as much mass as the Progress spacecraft. Most of the body of the craft will burn away as it hurtles through the atmosphere; however, some remnants could still reach Earth's surface.  

“Given the fact that material inside is somewhat protected during the early parts of re-entry, maybe somewhere 2,500 to 3,500 pounds of material might survive,” wrote Bill Ailor, an expert on spacecraft re-entries at the Aerospace Corp., in an email to Spaceflight Now. “Much of this material would itself be broken into smaller pieces and spread along a footprint several hundred miles long.”

To date, there has never been a case of a human being killed by falling, man-made space debris. It is unlikely that anyone will be hurt from the debris, and hopefully a few lucky people will get a safe view of Progress' re-entry.

You can track the descent of Progress 59 on satflare and N2YO.