Soviet Fears That Gagarin Might Use His Space Flight to Defect, Parachuting Into America

Mistrust prevailed. ... The capsule could be operated manually, but the risk was great. What if the cosmonaut were to take the opportunity to say "nyet!" to the [Soviet Union's] bright future and parachute into the American enemy's territory? A solution was quickly found: the manual controls of the aircraft were blocked by a padlock whose secret code was hidden in the cabin unbeknownst to its passenger. ... This Byzantine and risky system was foiled by colleagues of Gagarin, who, despite the top secret arrangement, promptly whispered the code into his ear before his departure.

As Russia — and the world — celebrate the 50th anniversary of the first human space flight, Le Monde's Marie Jégo points out — "cette obsession du secret !" — that the Soviet authorities were suspicious that Yuri Gagarin might use the occasion, and his Vostok space capsule, to try to defect to America.

La méfiance régnait. … La capsule pouvait être gérée manuellement mais le risque était grand. Et si le cosmonaute en avait profité pour dire "niet !" à l'avenir radieux et se parachuter chez l'ennemi américain ? Une solution fut bientôt trouvée : les commandes manuelles de l'appareil furent bloquées par un cadenas dont le code secret fut caché dans la cabine à l'insu de son passager. … Ce dispositif byzantin et hasardeux fut déjoué par les collègues de Gagarine, qui s'empressèrent, malgré l'interdiction, de lui souffler le code avant son départ.