It takes 13 hours to cross the Pacific Ocean. Our plane is like a Pringles tube of recycled air and anticipation. While 30,000 feet up in the atmosphere, we're exposed to approximately 150 μSV. The average natural background radiation is 0.27 μSV per hour. At cruising altitude, we get an average dose of 2.7 μSV per hour. There's less air between us and space, less gauzy blue molecules to deflect solar radiation.

We sail near cirrus. My mother snores. I fidget in my seat and worry about the circulation in my legs. The low but constant hum of machines dominates the day. The only solace is outside. The clouds below us are like a snowy field pinked by the morning sun. The attendants start handing out breakfast. It's strange to eat toast after a night of no night and no sleep.

Astronauts make leaving home look so glamorous.

(Image credit: Ryan Graff)