When the towers of the World Trade Center fell on September 11, 2001, one American was not on the planet.
Astronaut Frank Culbertson had been aboard the International Space Station for a month when the 9/11 attacks occurred, joined only by two Russian cosmonaut crew mates. He could only monitor the events of the day from 300 miles above the Earth.
On Friday, NASA released letters Culbertson wrote and images he took as the space station passed over the New York City area after the 9/11 attacks.
Culbertson wrote that he first heard of the attack via radio from a NASA flight surgeon.
"I was flabbergasted, then horrified. My first thought was that this wasn't a real conversation, that I was still listening to one of my Tom Clancy tapes," Culbertson wrote. "It just didn't seem possible on this scale in our country. I couldn't even imagine the particulars, even before the news of further destruction began coming in."
And he closed his letter on that first day:
"Other than the emotional impact of our country being attacked and thousands of our citizens and maybe some friends being killed, the most overwhelming feeling being where I am is one of isolation."
A day later, after having time to reflect on what was happening below, Culbertson continued his writing.
"It's horrible to see smoke pouring from wounds in your own country from such a fantastic vantage point. The dichotomy of being on a spacecraft dedicated to improving life on the earth and watching life being destroyed by such willful, terrible acts is jolting to the psyche, no matter who you are," he wrote.
And he continued to feel his isolation.
"It's difficult to describe how it feels to be the only American completely off the planet at a time such as this. The feeling that I should be there with all of you, dealing with this, helping in some way, is overwhelming."
The destruction of 9/11 also became more personal for him that day.
"I learned that the Captain of the American Airlines jet that hit the Pentagon was Chic Burlingame, a classmate of mine" at the U.S. Naval Academy, Culbertson wrote. "What a terrible loss, but I'm sure Chic was fighting bravely to the end. And tears don't flow the same in space ... "