Russia's Valentina Tereshkova was the first woman to reach space 50 years ago, shouting "Take off your hat, sky, I'm coming!" as she blasted off and into orbit.

The three-day mission rendered her an instant and global celebrity as well as a symbol for the Soviet's successful space program; however, it was not without its problems.

Tereshkova experienced a clean blast off and remained in a steady position until the second day when she suddenly became unresponsive.

"She sounded apathetic in conversations with ground control," Vladimir Yazdovsky, the chief doctor of the Soviet space program, later wrote in his memoirs, according to the Associated Press. "She largely limited her movements and kept sitting almost motionless."

Yazdovsky explained that Tershkova was having a bad reaction to weightlessness, so much so that some suggested an early landing, the news outlet reported.

Boris Chertok, the deputy for the father of Russia's space program, Sergei Korolyov, said in his chronicle that worries about Tereshkova were made worse by her failure to properly align the ship during a simulation testing her ability to perform a manual landing in case of autopilot failure during descent.

In the end, her ship landed perfectly on its own in and news of any tense moments were kept hidden from the public until the Soviet collapse, at which point top figures in the space program spoke out.

However, Tereshkova continues to deny that she ever felt unwell, saying that such a claim was merely groundless speculation. What was wrong, she said, was a design in the ship's controls, which would have left her to die in space had she not noticed in time. Asked not to speak about the problem, she kept her word until 1993, at which point she only spoke about it because a space engineer disclosed it.

Tereshkova eventually moved on to a career in government; today, she holds a Parliament seat on the ticket of the main Kremlin party where she serves as deputy chairman of the foreign affairs committee in the lower house.