Whenever he sees a veteran of the war in Afghanistan, Frank Culberston is reminded of where he was on Sept. 11, 2001. An encounter earlier this year is a good example. On a trip to Colonial Williamsburg, Virginia to watch the re-enactment of British occupation, he met a young veteran who had lost both legs while serving as an explosive ordinance device technician in Afghanistan. As he helped the soldier, who had two artificial legs, navigate the unpaved grounds, Culbertson mentioned he had witnessed the invasion of Afghanistan from above."From where, a C-130?" the soldier asked. A C-130 is a low-flying military aircraft used mainly to deliver troops and supplies to ground forces. "No, higher," Culbertson replied. "Oh, a U-2?" the soldier guessed, referring to the high-altitude reconnaissance aircraft. "Higher than that." From Aug. 12 to Dec. 15, 2001, astronaut Frank Culbertson was aboard the International Space Station (ISS). Two hundred fifty miles above the Earth's surface, Culbertson was the only American not on the planet at the time of the terrorist attacks. He -- along with two Russian cosmonauts -- witnessed the horrific events of Sept. 11, as well as the invasion of Afghanistan a month later, from space. View of New York from space. Photo courtesy of NASA. "I could always spot Afghanistan at night because it's basically dark," said Culbertson, who explained that surrounding countries, with their oil money, were pretty well lit at night. Some were even "grossly lit up," he said. "One night, I looked down on Afghanistan and I saw these big, bright explosions ... I was witnessing the invasion of Afghanistan in pursuit of Osama bin Laden and the Taliban," he said. A graduate of the United States Naval Academy and a former test pilot for the Navy, Culbertson was able to identify what he saw as explosions from cruise missiles and bombs being dropped from B-52s. "After the attacks on 9/11, I knew the world had changed." A month earlier, on the morning of Sept. 11, Culbertson, who had been in space for 30 days, had called down to mission control for a routine medical check-in. "I asked the doctor how things were going. He responded: 'We're not having a very good day on Earth,'" Culbertson recalled. Amid the chaos on the ground, mission control briefed Culbertson on what limited information they had: Two planes had crashed into the World Trade Center towers, and one plane had crashed into the Pentagon; all three were deliberate attacks by terrorists. "My immediate reaction was very visceral: My country was wounded, and it was hurting," Culbertson said. As he listened to mission control, struggling to make sense of the tragedy unfolding hundreds of miles below, he looked up at the map of the world flashing on the computer screen in front of him. In a few minutes, he would be directly over New York. He quickly left the radio, grabbed a video camera and raced to the cabin window that would have the best view of the city. [Tell your story: How has September 11 changed you?] "It was a very good weather day, and I could look down and see the entire northeastern U.S. very clearly. I saw a big column of black smoke rising over New York City, over Long Island, and out over the Atlantic. I zoomed the camera in, and as I did, I saw this big gray glob start to envelop the southern half of the city." He found out two days later that he was witnessing the collapse of the South Tower. Because the International Space Station travels at a speed of about 5 miles per second (it completes its orbit of Earth in only 90 minutes), the views of New York came and went very quickly. Because of the planet's rotation, the next time Culbertson and his crewmates passed over the U.S., they had a view of the Midwest and the Southwest, which was important to Culbertson. A married father of five, he wanted to make sure his family was out of harm's way. "I had a daughter studying at Purdue University at the time, so as we crossed over the Midwest, I'm looking throughout that area to make sure everything's all right over there. Most of the family was in Houston, and I could see all the way down to Texas," he said.