Jerrie Cobb, America's first female astronaut candidate who pushed for more women in space, has passed away after battling an illness. She was 88.

Journalist Miles O'Brien, who is serving as the family's spokesperson, confirmed the news on Thursday, April 18.

Becoming The First Female Astronaut Candidate

Cobb is best known for becoming the first woman to pass the grueling tests that aspirants had to go through to become an astronaut in 1960s. Twelve other women followed her and, together, they became known as Mercury 13.

However, the effort, which was privately funded, was not recognized by NASA. None of the 13 women who passed the preliminary screening process were permitted to enter the space training program.

Cobb could have been the first woman to make it to space. After Mercury 13, it had taken more than two decades before a woman made it to space. Sally Ride became the first American woman to fly in space on board the space shuttle Challenger on June 18, 1983.

Congress investigated why NASA decided not to allow the women to fly when they have the same qualifications as the men who later on carried out the flight test under Project Mercury. Cobb was among those who were called to speak in front of lawmakers.

"We women pilots who want to be part of the research and participation in space exploration are not trying to join a battle of the sexes," she stated. " As pilots, we fly and share mutual respect with male pilots in the primarily man's world of aviation. We very well know how to live together in our profession. We see, only, a place in our Nation's space future without discrimination."

Until her final year, Cobb held hope that she will be flown to outer space. In 1998, when NASA prepared to launch Mercury astronaut John Glenn aboard the space shuttle Discovery at the age of 77, she proposed that she be included in the geriatric study.

"I would give my life to fly in space, I really would," she told Associated Press. "It just didn't work out then, and I just hope and pray it will now."

NASA, however, did not fly another elderly person to space.

A documentary about the story of Mercury 13 women is now streaming on Netflix. A play based on the life of Cobbs titled The Promised Her The Moon is now running in San Diego.

A Gifted Pilot

Cobb was born on March 5, 1931, in Norman, Oklahoma. At age 12, she flew her father's open cockpit Waco plane. Four years later, she received her private pilot's license. She earned her commercial pilot's license when she was 18 years old.

In the 50s, she tried to set several world records for airspeed, altitude, distance. She also became the first woman to fly in the Paris Air Show and the fourth American to receive the Gold Wings of the Fédération Aéronautique Internationale.

She served as a humanitarian aid pilot in the Amazon jungle for decades.