Thousands of Americans applied for the next NASA astronaut class, breaking the record set in 1978.

NASA says more than 18,300 people applied to join the 2017 astronaut class, far surpassing the previous record of 8,000 in 1978 and more than three times the number of applications received in 2012.

“It’s not at all surprising to me that so many Americans from diverse backgrounds want to personally contribute to blazing the trail on our journey to Mars,” said NASA Administrator Charlie Bolden, himself a former astronaut. “A few exceptionally talented men and women will become the astronauts chosen in this group who will once again launch to space from U.S. soil on American-made spacecraft.”

The application process opened Dec. 14 and closed Thursday. It is the first step in an 18-month process that will end with the selection of eight to 14 people for the opportunity to become astronaut candidates.

For more about NASA astronauts, visit: www.nasa.gov/astronauts