The U.S. space agency has eight new astronauts _ its first new batch in four years.

Among the lucky candidates: the first female fighter pilot to become an astronaut in nearly two decades. A female helicopter pilot also is in the group. In fact, four of the eight are women, the highest percentage of female astronaut candidates ever selected by NASA.

Monday's announcement came on the eve of the 30th anniversary of the launch of the first American woman in space, Sally Ride. She died last summer.

The eight were chosen from more than 6,000 applications received early last year, the second largest number ever received. They will report for duty in August at Johnson Space Center in Houston and join 49 astronauts currently at NASA. The number has dwindled ever since the space shuttles stopped flying in 2011. Many astronauts quit rather than get in a lengthy line for relatively few slots for long-term missions aboard the International Space Station.

NASA Administrator Charles Bolden said these new candidates will help lead the first human mission to an asteroid in the 2020s, and then Mars, sometime in the following decade. They also may be among the first to fly to the space station aboard commercial spacecraft launched from the U.S., he noted. Russia ferries the astronauts now.

"These new space explorers asked to join NASA because they know we're doing big, bold things here _ developing missions to go farther into space than ever before," Bolden said in a statement.