In 2011 NASA opened applications for Astronaut Group 21. The team was announced in June 2013 after a year and a half long search. With four men and four women, the class of 2013 had the highest percentage of female finalists. According to NASA astronaut Kathleen Rubins, "it's… a reflection of how many really talented women are in science and engineering these days." NASA received a total of over 6,300 applications, which made it the second highest number received at the time.

NASA Astronaut Group 22 is a group of twelve NASA astronauts selected in June 2017. They were joined by two Canadian Space Agency astronauts for training.