HOUSTON—NASA Demo-2 astronauts Bob Behnken and Doug Hurley on Aug. 1 undocked from the International Space Station (ISS) aboard a SpaceX Crew Dragon capsule and prepared for the first splashdown of NASA astronauts since 1975 off the coast of Pensacola, Florida. 

The third and final phase of the spacecraft's two-month test flight will conclude with an 11-min. de-orbit burn of the capsule's Draco engines, which will be followed by an atmospheric re-entry and a parachute descent into the Gulf waters on Aug. 2 at 2:48 p.m.

“We’re about to embark on the final part of the journey,” Behnken said during a brief ceremony aboard the station's U.S. segment prior to the Crew Dragon’s departure. 

“The hardest part was getting us launched, but the most important part is bringing us home,” Behnken added. 

As Hurricane Isaias continues to track northward along Florida’s Atlantic Coast, NASA and SpaceX will continue to monitor weather conditions, including wind speeds, cloud ceilings, probabilities of rain and lightning, and wave heights in the Gulf of Mexico splashdown site for the Crew Dragon. 

If conditions at the primary and alternate splashdown zones were to turn “no-go” before the planned de-orbit maneuver, Behnken and Hurley could remain in orbit aboard their capsule, christened Endeavour, for an additional 24-48 hr.

In the hours prior to the undocking, the National Hurricane Center issued hurricane warnings along all but the southern- and northern-most regions of Florida's Atlantic coast. 

The center of Isaias was to approach the southern tip of Florida by early Aug. 2, churn to the northeast off the Atlantic coast, moving off the coast of Georgia as a tropical storm on Aug. 3.

A SpaceX recovery vessel staffed with about 40 company and NASA personnel, including flight surgeons, will be positioned in the waters near the splashdown zone.  

Two fast boats deployed from the landing zone vessel are to approach the capsule, check it for toxic propellant leaks and harness the two drogue and four primary parachutes, programmed to deploy at altitudes of 18,000 and 6,000 ft.  

Endeavour is to be hoisted aboard the recovery vessel so that Behnken and Hurley can be helped out within 60 min. of splashing down for initial medical checks.

With the checks complete, Behnken and Hurley could sail or be flown ashore via helicopter, potentially to their Kennedy Space Center launch site. At Kennedy, they are to board a NASA jet for a flight to NASA's Johnson Space Center here in Houston, where they trained and near where they reside with their families.

Demo 2 lifted off on a SpaceX Falcon 9 from NASA's Kennedy Space Center on May 30, marking the start of the test flight's first phase. 

The spacecraft docked to the orbiting science lab's Harmony module on May 31, allowing Behnken and Hurley to join ISS Expedition 63 commander Chris Cassidy, of NASA, and Russian cosmonauts Anatoly Ivanishin and Ivan Vagner.