"Congratulations SpaceX & NASA on completing first crewed Dragon flight!", Musk wrote on Twitter after the splash-down, adding a United States flag emoji followed by "returned" - referring to a rivalry with Boeing over which company's astronaut crew would be the first to retrieve an American flag left on the space station in 2011, when the last crewed mission launched from U.S. soil.
"We're both super, super proud having been just a small part of the team that accomplished bringing those spaceflights back to the Florida coast and bringing that capability back to America", astronaut Behnken said.
Said SpaceX founder Elon Musk after the astronauts were safely on land: "I'm not very religious but I prayed for this one".
Spacecraft engineers, recovery experts and medical professionals on the SpaceX recovery ship, called Go Navigator, are helping the astronauts get out of the capsule as they begin readjusting to gravity.
Detection of the fumes in fact caused a short delay in opening the hatch to release the astronauts from the capsule.
Around an hour after splashdown, the astronauts exited the capsule and headed for shore on a helicopter. Hurley piloted the last shuttle mission in 2011.
"We definitely are old dogs and like some of our old tricks". "It's a testament to what we can accomplish when we work together to do something once thought impossible". NASA has said the arrangement lets the agency focus its attention on more ambitious missions to the moon or Mars, while commercial companies take over more routine spaceflight operations in low-Earth orbit, such as carrying cargo or crew members to the space station.
"Thank you again from the Good Ship Endeavour", Behnken told mission controllers.
"It's been a great two months, and we appreciate all you've done as a crew to help us prove out Dragon on its maiden flight", Hurley said to commander Chris Cassidy.
The US has paid the two companies a total of about $7 billion for their "space taxi" contracts, though aerospace giant Boeing's efforts have badly floundered.
NASA Chief Astronaut Pat Forrester, left, and NASA astronaut and Crew Recovery Chief Shane Kimbrough prepare for the landing.
They arrived at the ISS in the Crew Dragon on May 31, where they performed tests on Crew Dragon in addition to conducting research and other tasks with the space station crew.
The spacecraft went from an orbital speed of 28,000kph to 560kph during atmospheric re-entry.
It deployed two sets of parachutes on its descent, bringing its speed down to a mere 15 miles per hour as it hit the Gulf of Mexico. Baikonur was ground zero for the Soviet Union's first victories in the space race, including the launch of Sputnik 1 - the first artificial satellite - and Vostok 1 - the first human spaceflight. "Congratulations to the entire SpaceX and NASA team on such an extraordinary mission".
Take-off is set for late September and the crew are due to spend six months on the space station.