NASA-SpaceX mission: Astronauts prep for splashdown from historic mission, despite tropical storm - CNN

Behnken and Hurley's safe homecoming will mark the end to an historic two-month mission and pave the way for the US to once again become a world leader in human spaceflight.

Crew Dragon return: Live updates

The astronauts have been aboard the Crew Dragon spacecraft, named Dragon Endeavour, since Saturday evening when it undocked from the International Space Station.

Behnken and Hurley began their historic two-month trip to the ISS in May, when the astronauts launched inside their Crew Dragon spacecraft from a ground pad in Florida.

It was the first NASA astronaut launch from US soil since 2011 and the first time in history that a commercially developed spacecraft carried humans into orbit.

Overnight, the vehicle conducted a series of engine burns to lower the vehicle's altitude, preparing to take a dramatic plunge back into the Earth's thick atmosphere later today.

Adding to the drama is Tropical Storm Isaias, which is barreling toward Florida's east coast and threatening violent winds capable of damaging roofs and buildings.

NASA and SpaceX predetermined seven potential splashdown sites for this mission, four of which are to the west of Florida in the Gulf of Mexico: Pensacola, Tampa, Tallahassee and Panama City.