Video: Falcon 9 launch replays

For the second time in a year, a large spent Chinese rocket stage intentionally left in orbit is heading for an unguided plunge back into Earth’s atmosphere Saturday or Sunday somewhere between 41.5 degrees north and south latitude.

Government investigators have exonerated SpaceX’s Falcon 9 rocket in the loss of a top secret space mission known as Zuma in January, blaming a malfunction in a component modified by Northrop Grumman that connected the launcher with its classified payload, according to the Wall Street Journal.

Launching the high-tech GOES-R satellite to revolutionize U.S. weather forecasting, a United Launch Alliance Atlas 5 rocket thunders away from Cape Canaveral on Saturday at 6:42 p.m. EST (2342 GMT).