In 1962, Cobb was called to testify before a Congressional hearing, the Special Subcommittee on the Selection of Astronauts, about women astronauts. Astronaut John Glenn stated at the hearing "men go off and fight the wars and fly the airplanes", and "the fact that women are not in this field is a fact of our social order". Only a few months later, the Soviet Union would send the first woman into space, Valentina Tereshkova. Soon afterward, Tereshkova ridiculed Cobb for her religious beliefs but sympathized with the sexism she encountered: “They (American leaders) shout at every turn about their democracy and at the same time they announce they will not let a woman into space. This is open inequality.” Cobb lobbied, along with other Mercury 13 participants, including Jane Briggs Hart, to be allowed to train alongside the men. However, at the time NASA requirements for entry into the astronaut program were that a pilot be a military test pilot, experienced at high speed military test flying, and have an engineering background enabling the pilot to take over controls in the event it became necessary. Since all military test pilots were men at the time, this had the effect of automatically excluding women. An exception was not made for Cobb. Liz Carpenter, who was the Executive Assistant to Vice President Lyndon Johnson, drafted a letter to NASA administrator James E. Webb questioning these requirements, but Johnson did not send the letter, instead writing across it: "Let's stop this now!" Cobb then began over 30 years of missionary work in South America, performing humanitarian flying (e.g., transporting supplies to indigenous tribes), as well as surveying new air routes to remote areas. Cobb "pioneered new air routes across the hazardous Andes Mountains and Amazon rain forests, using self-drawn maps that guided her over uncharted territory larger than the United States". It was because of Cobb that many once isolated South American inhabitants started receiving much needed supplies and medicines. The new routes she discovered helped better the lives of countless individuals. Cobb has been honored by the Brazilian, Colombian, Ecuadorian, French, and Peruvian governments. In 1981, she was nominated for the Nobel Peace Prize for her humanitarian work. In 1999, the National Organization for Women conducted an unsuccessful campaign to send Cobb to space to investigate the effects of aging, as John Glenn had been. John Glenn's main purpose on his space flight was to observe the effects of a micro-gravity environment on the body of an aged individual. Specifically, NASA wanted to observe whether the effects of weightlessness had positive consequences on the balance, metabolism, blood flow, and other bodily functions of an elderly person.