(1921– )
a US astronaut and politician. He joined the NASA Mercury program in 1958 and was the first American to complete an orbit (= circular path in space) of the earth, in the spacecraft Friendship 7 . Glenn left NASA two years later and was elected a Senator from Ohio for the Democratic Party until 1998. He twice tried but failed to become the Democratic candidate for US President . In 1998 he again took part in a space flight, at the age of 77.