Sunita Williams leads with experience in NASA's Man on Mars team

Sunita Williams will be one of the four astronauts who will fly commercial space exploration flights by Boeing and SpaceX, reports AFP.  

Sunita Williams, 49, is the most experienced astronaut of the quartet. She is a Navy captain and helicopter pilot who has already spent nearly a year (322 days) in space. According to NASA, at 50 hours and 40 minutes Williams holds the record for total cumulative spacewalk time by a female astronaut.

The other members are; Doug Hurley, 48, who has piloted two space shuttle missions; Eric Boe (50) and Robert Behnken (44) are both Air Force colonels who have flown on two space shuttle missions each. "We are excited to have such an experienced group of astronauts working with the Commercial Crew Program, Boeing and SpaceX and ultimately flying on the companies' flight test missions," said NASA Commercial Crew Program Manager Kathy Lueders told AFP.

"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," NASA Administrator, Charles Bolden said. The commercial flights will begin in 2017 where the astronauts will be taken to the International Space Station.  The US space shuttle program was retired in 2011. The flights will restore US access to space.

NASA has been encouraging companies, like Boeing and SpaceX, to build a successor to the space shuttle.