Wherever human beings travel, we bring our religions with us. "Godspeed, John Glenn," the farewell words spoken to the first American astronaut into orbit, exemplifies the characteristic human drive to carry faith into space.

Many astronauts who are religious have spoken of finding their faith strengthened by the experience of traveling in space. The ability to look back on Earth as a small blue planet, and to see the fragility of life and human existence, is an experience that brings many space travelers closer to the creator. The astronauts of the Apollo 8 mission, orbiting the Moon for the very first time in 1968, broadcast back to Earth a reading from the book of Genesis on Christmas day, in the belief that the passage discussing the creation of the world expressed their feelings of the awe and majesty of creation.

While some astronauts are agnostic or atheist, others have been...