NASA astronauts aboard SpaceX’s Crew Dragon capsule splash down in the Gulf of Mexico

Astronauts Bob Behnken and Doug Hurley have left the Dragon Endeavour capsule aboard the Go Navigator rescue ship, marking the end of the maiden voyage of NASA’s commercial crew program.

The astronauts splashed down in the Gulf of Mexico off the coast of Pensacola, Fla., just as schedued at 2:48 p.m. Eastern time. Forty minutes later, the spacecraft was hoisted aboard the recovery ship. But SpaceX technicians delayed opening the side hatch to allow medical crews to evaluate Behnken and Hurley because of concerns about toxic fumes.

The astronauts were return to shore via helicopter and be flown to Ellington Field Joint Reserve Base in Houston and the Lyndon B. Johnson Space Center.

Said Behnken, who was first out of the capsule: “Thank you for doing the most important parts and most difficult parts of human spaceflight, sending us into orbit and bringing us home safely. Thank you very much for the good ship Endeavour.”

Hurley came out moments later. “For anyone who’s touched Endeavour, you should take a moment to cherish this day given everything that’s happened this year.”

SpaceX landing crews delayed opening the hatch of the Crew Dragon Endeavour capsule aboard the recovery ship Go Navigator because of high levels of harmful fumes.

Mission controllers detected higher-than-appropriate amounts of “hypergolic fumes,” or fumes that could explode when coming in contact with one another. Technicians aboard the Go Navigator spent several minutes aerating the service components of the Endeavour to disperse the fumes, which never entered the cabin of the spacecraft. Tests found no toxic fumes inside the capsule.

Even with the delay, SpaceX’s egress, or exit, timeline was well on schedule. Flight planners predicted an hour-long process from the time Endeavour splashed down off the coast of Pensacola, Fla., to when technicians on Go Navigator would open the hatch and allow medical officials to evaluate Behnken and Hurley.

After an hour and one minute past splashdown, which occurred at 2:48 p.m., mission controllers reported the fumes were below harmful levels, but chose to continue the aeration process as an extra safety measure. Asked if they wanted to come out sooner, Hurley said they were happy to wait as long as necessary.

It’s called Demo-2 for a reason. Demo is short for demonstration, meaning SpaceX’s mission to fly a pair of NASA astronauts to and from the International Space Station is one big test, a way to prove the company is capable to pulling off the feat safely.

The launch and docking two months ago was picture perfect, NASA and SpaceX said. So did the return and splashdown. That means the space agency is likely to certify SpaceX’s vehicles and allow them to begin flying regular operational missions.

The first one, called Crew-1, could happen as soon as late September. NASA has already picked the crew, a quartet of astronauts from different backgrounds.

Victor Glover is a former Navy pilot who flew F/A 18 Hornets. A father of four, he’s never been to space before.

Mike Hopkins is a former football player at the University of Illinois who applied four times to become an astronaut, waiting more than 10 years before he was finally selected in 2009. Since then, he’s flown to space once on the Russian Soyuz.

Shannon Walker was selected to be an astronaut in 2004 after working closely with the space agency, first as a robotics flight controller with Rockwell Collins. In 1995, she joined NASA, working on the space station program. She flew to space on the Soyuz in 2010.

They will be joined by Soichi Noguchi, a Japanese astronaut, who has flown to space twice, including the first Space Shuttle mission after the 2003 Columbia disaster.

NASA astronauts Doug Hurley and Bob Behnken reported a successful splashdown in the Gulf of Mexico off the coast of Pensacola, Fla., completing their return mission to Earth from the International Space Station.

Moments after the SpaceX Dragon Endeavour capsule hit the water, mission controllers radioed to the crew congratulating them on their return journey.

“On behalf of the SpaceX and NASA teams, welcome home and thanks for flying SpaceX,” mission control said.

“It’s truly our honor and privilege,” Hurley responded. “On behalf of the Dragon Endeavour, congrats to NASA and SpaceX.” He later radioed back, “All is well.”

SpaceX fast boats will soon approach the Endeavour to recover its parachutes from the water and check for any leaking propellants. The Go Navigator mother ship will then approach and hoist the Endeavour aboard, where recovery crews will secure the capsule and open the side hatch, allowing medical professionals to evaluate the astronauts and help them out of the spacecraft.

Astronauts Bob Behnken and Doug Hurley are back on Earth, but still a ways from home. SpaceX landing crews will launch two speed boats from the recovery mother ship Go Navigator, stationed three miles away from the projected landing site, to verify that the Endeavour spacecraft is safe and prepared for recovery.

The first boat will check to see if the Dragon capsule is leaking any fluids, propellant or vapors. The second boat will retrieve Endeavour’s four parachutes, which the capsule ejects upon splashdown.

The Go Navigator recovery ship will then approach the Endeavour and hoist it aboard, allowing SpaceX crews to secure the capsule in place and open the side hatch to medically evaluate Behnken and Hurley before they disembark.

The SpaceX Dragon Endeavour capsule carrying NASA astronauts Doug Hurley and Bob Behnken has splashed down in the Gulf of Mexico off the coast of Pensacola, Fla., completing an 18-hour flight to Earth from the International Space Station.

The landing marks the end of the first mission for a NASA crew aboard a private-sector spacecraft. SpaceX, owned by billionaire entrepreneur Elon Musk, beat out industry titan Boeing to send the first manned mission to space as part of NASA’s commercial crew program. Hurley and Behnken lifted off from Kennedy Space Center in Cape Canaveral, Fla., on May 30, and spent 62 days aboard the ISS while NASA and SpaceX officials evaluated the Endeavour’s performance and flightworthiness.

The Dragon capsule has deployed its two drogue parachutes to slow its velocity as it plummets back to Earth on a return mission from the International Space Station. The chutes deploy when Dragon reaches an altitude of 18,000 feet and is traveling at 350 miles per hour.

SpaceX flight engineers have regained communication with astronauts Bob Behnken and Doug Hurley inside the Dragon capsule. Flight crews lost signal with Dragon for about six minutes as the capsule was engulfed in a blazing ball of heat while it reentered Earth’s atmosphere.

SpaceX flight engineers have lost contact with astronauts Bob Behnken and Doug Hurley inside the Dragon capsule as it continues its return mission from the International Space Station. This temporary communication blackout was expected — engineers call the event “LOS,” or “loss of signal” — and is caused by the intense heat that surrounds the capsule as it reenters Earth’s atmosphere. The communication disruption is expected to last six minutes, according to flight plans.

Conditions at the splashdown site are excellent.

The nose cone that protects the forward hatch on SpaceX’s Dragon capsule has closed, readying the spacecraft to plunge through the Earth’s atmosphere on its return mission from the International Space Station.

The cone closed after the Endeavour capsule fired its Draco thrusters to align its trajectory with its scheduled landing site in the Gulf of Mexico off the coast of Pensacola, Fla. About 20 minutes after the cone’s closure, the spacecraft will perform several small “attitude adjustments,” or repositioning maneuvers to direct its heat shield downward as it prepares to enter Earth’s atmosphere, where it will enduring temperatures up to 3,500 degrees Fahrenheit and decelerate from 17,500 miles per hour down to just 15 mph when it splashes down.

There is a lot of new technology loaded into SpaceX’s Crew Dragon spacecraft. It has touchscreens, like a tablet. Emergency abort thrusters that can fire automatically. It docked autonomously with the International Space Station, like a self-driving car.

But for all the advances that make Dragon a next-generation spacecraft, it will rely on some old and relatively basic engineering to get the astronauts home safely: parachutes.

And the design of the parachutes used by SpaceX turned out to be surprisingly tricky.

“Parachutes are way harder than they look,” SpaceX founder Elon Musk said in an interview with The Post in the days leading up to the launch. “The Apollo program actually had a real morale issue with the parachutes because they were so damn hard. They had people quitting over how hard the parachutes were. And then you know we almost had people quit at SpaceX over how hard the parachutes were. I mean, they soldiered though, but, man, the parachutes are hard.”

If all goes well, two drogue parachutes will deploy when the spacecraft is at about 18,000 feet, traveling at some 350 m.p.h. Then, as it slows down to about 119 m.p.h., four main parachutes should deploy at about 6,000 feet.

SpaceX has struggled with its parachute design, upgrading the model from what it calls the Mark 2 design to Mark 3 after it suffered a failure during its test program. The upgraded version uses a stronger material in the lines that run to the canopy and a new stitching designed to handle the loads at deployment.

At a press conference late last year, Musk said the Mark 3 parachutes are “probably 10 times safer” than the Mark 2 version. “In my opinion they are the best parachutes ever. By a lot.”

The SpaceX Endeavour capsule has started its “de-orbit burn,” a nearly-12-minute firing of its engines that will plunge it into Earth’s atmosphere from space and begin the most harrowing part of its descent toward the coast of Florida.

Flying through the planet’s atmosphere, the Endeavour will be engulfed by a 3,500-degee Fahrenheit fireball, testing the spacecraft’s heat shield. SpaceX flight engineers will lose communications with astronauts Bob Behnken and Doug Hurley for close to six minutes while the capsule endures that blast of heat.

After emerging, Endeavour will fire off drogue parachutes to slow its momentum, then four larger parachutes to gently lower it into the Gulf of Mexico off Pensacola, Fla.

The astronauts aboard the Dragon Endeavour spacecraft at 1:52 p.m. jettisoned the capsule’s trunk, an annex that contains thermal control, power and avionics system components, in preparation for returning to Earth from the International Space Station.

NASA astronauts Doug Hurley and Bob Behnken left the ISS on Saturday and traveled nearly 17 hours to just outside the Earth’s atmosphere. Jettisoning the trunk is one of the mission’s final steps before committing to return to Earth and splash down in the Gulf of Mexico off the coast of Pensacola, Fla.

The Endeavour will soon begin a 12-minute “de-orbit burn” in which it will fire its engines to plunge out of Earth’s orbit and into the atmosphere. If SpaceX flight engineers detect unsuitable splashdown conditions, they can call for a last-minute “wave-off” before the engine burn, meaning the Endeavour will stay in orbit for at least another day until conditions improve. But such an eventuality is not expected.

The SpaceX Dragon capsule started its final orbit around the Earth at 12:51 p.m. Eastern time, before beginning its descent to Earth.

About an hour after that final orbit begins, SpaceX flight engineers will give the final “go” order for the capsule’s return, carrying NASA astronauts Bob Behnken and Doug Hurley to the Gulf of Mexico off the coast of Pensacola, Fla.

The Endeavour capsule will jettison its trunk, an annex that contains thermal control, power and avionics system components, at approximately 1:51 p.m., then fire its engines for a nine-minute “de-orbit burn” that will catapult the spacecraft out of orbit and through Earth’s atmosphere.

SpaceX flight engineers gave a provisional “go” order for that burn shortly after the final orbit sequence began. Engineers, though, can still “wave off” the landing attempt at any time before the “de-orbit burn” if conditions change. The Endeavour has three days’ worth of “consumables” — food, water and oxygen — on board if the crew needs to postpone reentry.