Sunita Williams is one of four astronauts who will fly on a commercially owned and operated spacecraft, built by contractors, not NASA. They will launch to space from U.S. soil for the first time since the space shuttle was retired in 2011. (ReelNASA/YouTube)

Combined, they have spent more than a year in space, orbited the Earth hundreds of times and traveled tens of millions of miles. They are decorated military veterans, fighter jet and helicopter pilots turned NASA astronauts, who have all flown to the International Space Station.

Now they are going back, becoming the first astronauts to launch to space from U.S. soil since the space shuttle was retired in 2011, NASA Administrator Charles Bolden announced Thursday. But unlike their previous launches, which were aboard either the space shuttle or a Russian rocket, the four astronauts — Sunita Williams, Robert Behnken, Eric Boe and Douglas Hurley — will fly next on commercially owned and operated spacecraft, built by contractors, not NASA.

In a dramatic departure, NASA last year awarded contracts to Boeing and SpaceX to ferry astronauts to the space station, the orbital laboratory about 250 miles above the Earth’s surface. By outsourcing the missions to low-Earth orbit, NASA says it can then focus on its main goal: flying to deep space, even Mars.

“These distinguished, veteran astronauts are blazing a new trail, a trail that will one day land them in the history books and Americans on the surface of Mars,” Bolden said in a statement.

Since the shuttle’s retirement, the U.S. has been forced to rely on Russia to take its astronauts to the station, an expensive and troubling arrangement that now costs $76 million per seat.

By relying on contractors, the U.S. will save nearly $20 million per flight, Bolden said, and allow more astronauts to fly at a time.

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The first flight, expected to occur near the end of 2017, had been pushed back from this year because of funding delays. But now even the revised timeline is in jeopardy, some fear, after Congress has slashed $300 million from the program.

If the cuts stand, they will delay the program by two more years, Sen. Bill Nelson (D-Fla.) has said. Bolden has also blasted Congress, saying that “by gutting this program and turning our backs on U.S. industry, NASA will be forced to continue to rely on Russia to get its astronauts to space — and continue to invest hundreds of millions of dollars into the Russian economy rather than our own.”

There are also renewed concerns about whether it is prudent to rely so heavily on contractors for such important missions. Both Orbital Sciences (now Orbital ATK) and SpaceX, the companies used by NASA to fly food and supplies to the station on unmanned missions, have seen their rockets explode in recent months. And now, both companies are temporarily sidelined as they work to fix whatever problems caused the failures.


Clockwise from top left: astronauts Eric Boe, Sunita Williams, Douglas Hurley and Robert Behnken.

Despite the explosions, though, NASA has said it remains confident in the companies and is moving ahead with its plans. Bolden called the program “a worthy successor to the incredible 3-year run of the space shuttle program.”

[SpaceX's rocket just blew up. Here's why that's such a big deal.]

The astronauts chosen by NASA to fly on the upcoming missions are among the agency’s best and most experienced. Here’s a look at their backgrounds:

Sunita Williams is a Navy captain and a Naval Academy graduate. A helicopter pilot, she deployed during the Persian Gulf War and later became a helicopter test pilot instructor. Selected to be an astronaut by NASA in 1998, she has spent a total of 322 days in space over two missions and has spent more time on spacewalks — 50 hours and 40 minutes — than any other female astronaut. She is also a triathlete and enjoys bowhunting.

Douglas Hurley is a retired Marine Corps colonel who became the first Marine test pilot to fly the F/A-18E/F Super Hornet. He has flown two space shuttle missions to the space station, one on Endeavour, the other on Atlantis, and has spent a total of 683 hours in space.

Eric Boe is a colonel in the Air Force who flew 55 missions monitoring the airspace over southern Iraq after the Persian Gulf War as part of Operation Southern Watch. On his first flight to the space station in 2008, he helped expand the station’s living quarters and delivered a new bathroom, kitchen and exercise machine. During his second mission, the last for space shuttle Discovery, he orbited Earth 202 times and traveled 5.3 million miles.

Robert Behnken is also an Air Force colonel. He served as an F-22 test pilot and flew two space shuttle missions, the first in 2008, the second two years later. He’s performed a total of six spacewalks.

“I view exploration as a challenge, and trying to continue to feed that challenge means doing new and exciting things,” Behnken said in an interview on NASA TV. “Whether it’s climbing [Mount] Kilimanjaro or something you haven’t done before.”