By Jeffrey Kluger
Updated: March 8, 2019 12:35 PM ET

There was nobody aboard the SpaceX Crew Dragon to feel the jolt when the spacecraft splashed down in the Atlantic Ocean at 8:45 a.m. ET Friday morning off the Florida coast after six days in orbit. There aren’t all that many people left in the world who can even describe firsthand what a splashdown feels like, since the last time one occurred was at the end of the final Apollo mission, in the summer of 1975.

The next best thing to a person was aboard the Crew Dragon however: a full-sized dummy in a SpaceX spacesuit — named Ripley, after Sigourney Weaver’s character in the Alien series — outfitted with sensors to record and report all of the physical experiences of the flight, including the hard slap as the bottom of the spacecraft hit the water. As early as July, Ripley the dummy astronaut could be followed by the real deal, as two Americans are scheduled to take off aboard the first crewed Crew Dragon, ending a drought of astronaut launchings from American soil that began in the summer of 2011 when the last space shuttle flew and the program was mothballed. (Of course, that mission could always be delayed, as spaceflights that monumental so often are.)

“Today’s successful re-entry and recovery of the Crew Dragon capsule after its first mission to the International Space Station marked another important milestone in the future of human spaceflight,” said NASA Administrator Jim Bridenstine in a statement. “I want to once again congratulate the NASA and SpaceX teams on an incredible week.”

Crew Dragon’s near-perfect flight — an on-time launch, a flawless docking, and six days of operating in the punishing environment of space — did not guarantee a perfect reentry. Indeed, nearly all orbital missions are bookended by danger, with the fiery liftoff at the beginning and the high-dive fall at the end easily presenting the greatest opportunities for disaster. And Crew Dragon, as a first-timer to space, faced more risks than more tried-and-tested craft.

“We were all very excited to see re-entry, parachute and drogue deploy, main deploy, splashdown — everything happened just perfectly,” said Benji Reed, director of crew mission management at SpaceX, in a statement. “It was right on time, the way that we expected it to be. It was beautiful.”

SpaceX may have launched 16 uncrewed cargo missions to the International Space Station since 2012, but the cargo Dragon and the Crew Dragon are not the same animals. The biggest difference is at the base of the vehicle — specifically, the heat shield that protects the ship from the more than 3,000º F fires of reentry. The cargo vessel’s heat shield is little different in shape from the designs that protected NASA’s manned Mercury, Gemini and Apollo spacecraft — round and slightly convex, to disperse the superheated plasma that is produced by the ship’s plunge through the steadily thickening air.

But the bottom of the Crew Dragon is slightly asymmetrical, its perfect contours rendered imperfect by the four pairs of engines built around the base of the ship. These are its escape rockets, which would blast the spacecraft and the crew away from the Falcon 9 rocket carrying them to orbit if the rocket was becoming unstable or threatening to explode during a launch.

The one-man Mercury and three-man Apollo spacecraft had similar escape systems (the two-man Gemini used ejection seats) but they were built into a tower that was mounted onto the nose of the spacecraft. But that tower had to be jettisoned before the spacecraft reached orbit — before the spacecraft even separated from the rocket, in fact — briefly leaving the crew with no escape system at all if something went wrong.

The Crew Dragon never loses its built-in escape rockets, which eliminates that danger and simplifies the system overall. The asymmetry in the Dragon that results, however, complicates the aerodynamics of reentry, introducing the possibility that the ship could begin rolling uncontrollably while screaming down to Earth.

“I think it’s unlikely,” SpaceX founder and CEO Elon Musk said on March 2, in the hours before the Crew Dragon’s launch. “We’ve run simulations a thousand times, but this is a possibility.”

That possibility never became reality — at least not this time — partly because Musk wasn’t being hyperbolic about those thousand simulations, which SpaceX and NASA exhaustively conducted via computer models. But one real flight beats any number of make-believe ones, and as the Dragon reentered and its attitude remained stable, there was a lot of relief at the company’s mission control in Hawthorne, California.

The parachutes were another source of anxiety, simply because the stakes are so binary: If the chutes deploy as they’re supposed to, the spacecraft and the crew land safely. If they don’t, the crew dies.

“The bottom line is that the thing has to work every time,” NASA astronaut Dough Hurley, one of the two crew members assigned to the July mission, told Ars Technica. “You know what I mean? It has to be 100 percent foolproof.”

The spacecraft achieved that standard Friday morning, with the drogue chutes and then the four giant main chutes billowing open fully and on time — thanks again to rigorous testing.

In recent years, NASA and SpaceX have conducted 18 airplane drop tests of dummy Dragons with functioning chutes, and grew increasingly convinced of the system’s reliability. That confidence was shaken, however, during an August 2018 SpaceX cargo mission, when some unexpected — and thus far undisclosed — problems occurred with the parachutes. NASA and SpaceX have not been forthcoming about what those problems were, and continue to refer to them vaguely as “anomalies,” even in an October safety advisory panel report submitted to Bridenstine.

Still more parachute tests are planned before the scheduled crew launch, in the hope both of refining the technology and easing industry and government jitters. A live-fire test of the escape system is planned too, with the same Dragon that returned Friday morning taking off again aboard a Falcon 9 rocket and deliberately aborting over the ocean. When the Dragon is safely away from the rocket, it will descend under parachutes — one more test of that critical system, too.

The reusability of SpaceX’s Dragon is one of its selling points, and is also the reason Friday morning’s splashdown happened in the Atlantic Ocean, rather than the calmer and bigger Pacific. Land off the West Coast and you have to truck or fly your Dragon all the way across the country to get it back to Cape Canaveral and readied for another launch. Land in the Atlantic and you just scoop it up and bring it in to shore.

There is a certain circularity to an Atlantic return. It’s the ocean in which America’s first astronauts — Al Shepard and Gus Grissom — plopped down after their seventeen-minute sub-orbital missions in 1961. America was going to space for the first time then; it’s returning now.

The Atlantic, always patient, has been waiting.

Write to Jeffrey Kluger at jeffrey.kluger@time.com.

SPONSORED FINANCIAL CONTENT

Read More From TIME

EDIT POST