Members of Nasa's newest astronaut class, a group that includes the highest number of women since the program began more than 50 years ago, have been speaking about their selection.

The agency's 21st astronaut class, announced on Monday, includes four women and four men, who made it through a pool of 6,100 applicants, the largest ever. Those who make it through the program will have the opportunity to be on missions to the Earth's orbit, an asteroid and Mars.

"My parents are going to be excited. They know this has been a lifelong goal," said Tyler Hague, 37. "My brothers, as they always do, will give me a hard time."

Hague said it was his third time applying for the program. Since the program began in 1959, 330 people have made it through the selection process.

"I truly don't remember ever wanting to be something else," said Anne McClain, 34. The US army major is the youngest candidate selected for the program.

The eldest candidate is 39-year-old John Cassada. Each of the potential candidates holds multiple university degrees and have aeronautical experience.

To be accepted in the program, candidates must meet stringent academic and physical qualifications – including being between 62 and 75 inches tall.

"The thing that really draws me and excited me about the future is the opportunity to be a part of kindling America's passion for aerospace and space," said Victor Glover, 37. Glover is a US navy lieutenant commander who was waiting to hear where he would be stationed next when he learned he made it into the program.

The candidates begin training at a Nasa training center in Houston in August. Candidate training lasts about two years where candidates undergo more physical and mental tests.

"They're excited about the science we're doing on the International Space Station and our plan to launch from US soil to there on spacecraft built by American companies," said Nasa administrator Charles Bolden. "And they're ready to help lead the first human mission to an asteroid and then on to Mars."