Martin Rees

As an astronaut, when you're getting ready to go out of that hatch, you know that's the pinnacle of both your career and your life. The view completely blows you away. The real challenge is getting past the excitement and getting focused and down to work.

I was only 8 years old on July 20, 1969, when Neil Armstrong, 38-year-old commander of 'Apollo 11,' descended the cramped lunar module Eagle's ladder with hefty backpack and bulky spacesuit to become the first human on the moon.