Apollo 11 astronaut Michael Collins, who orbited the moon alone while Neil Armstrong and Buzz Aldrin made their historic first steps on the lunar surface, died Wednesday. He was 90. Collins died of cancer, his family said in a statement: “Mike always faced the challenges of life with grace and humility, and faced this, his final challenge, in the same way.” Collins was part of the three-man Apollo 11 crew that in 1969 effectively ended the space race between the United States and Russia and fulfilled President John F. Kennedy’s challenge to reach the moon by the end of the 1960s. Though he traveled some 238,000 miles to the moon and came within 69 miles, Collins never set foot on the lunar surface like his crewmates Aldrin and Armstrong, who died in 2012. None of the men flew in space after the Apollo 11 mission. “It’s human nature to stretch, …