Earth is a small town with many neighborhoods in a very big universe.

And in that moment, I was hit with the realization that this delicate layer of atmosphere is all that protects every living thing on Earth from perishing in the harshness of space.

This was exactly what I experienced in space: immense gratitude for the opportunity to see Earth from this vantage, and for the gift of the planet we've been given.

I lay on my back, surprised at how calm and focused I felt, strapped to four and a half million pounds of explosives.

Weightlessness was wonderful, and I was surprised at how natural it felt.

At this point I thought 'We made it,' by which I meant 'We survived.' I also was acutely aware that my childhood dream of flying into space had just come true.