One night in February 1962, John H. Glenn, Jr. flew overprefix = st1 /Australia. The man in the Mercury    capsule was alone, but friendly voices reached him by radio. Over the dark land 100 miles below, he saw sparkling lights. It marked the city of Perth, where people had turned on their lights as a greeting to him.    In Friendship 7, Glenn radioed, "The lights show up very well. Thank everybody for turning them on." His capsule moved on to the east.    "During his three orbits of the earth, Glenn could always reach one of the 18 tracking stations. Some of them were on ships at sea. Others were in theUnited States.    Many of the stations had been built with the help of other countries. These countries allowed  Americans to bring in radio equipment and set it up. Without the help of such lands asNigeria,  Zanzibar andMexico, there would have been breaks in the worldwide radio network. John Glenn, Jr. was the first American to orbit the earth. For his flight, the tracking network covered 60,000  statute miles  . 500 men worked in the stations along the route. Since his flight, the  network has grown. Today, it covers more than 100,000 statute miles and has about 100 stations. One-third of these stations are outside theUnited States. During his flight Glenn could   _
reach the ships at sea visit the tracking stations see lights on the ground clearly get in touch with people on land