9/11 Anniversary: NASA Shares Images of That Day Taken by US Astronaut on ISS

The agency noted that the September 11th attacks are considered a national catastrophe in the US that resulted in a "staggering loss of life" and, importantly, a profound shift in American culture. On that dark September Tuesday, aboard the ISS was the only American astronaut to capture the moment that, some say, could define the 21st century.

NASA is commemorating the 20th anniversary of the September 11 terrorist attacks, which killed almost 3,000 people.

In a satellite image shared by NASA on Saturday, billowing smoke above Manhattan can be seen from space after two hijacked planes crashed into the two World Trade Center towers.

"The smoke seemed to have an odd bloom to it at the base of the column that was streaming south of the city. After reading one of the news articles we just received, I believe we were looking at NY around the time of, or shortly after, the collapse of the second tower. How horrible…" NASA astronaut Frank Culbertson, who took the photos from up above the NYC, said.

Visible from space, a smoke plume rises from the Manhattan area after two planes crashed into the towers of the World Trade Center. This photo was taken of metropolitan New York City (and other parts of New York as well as New Jersey) the morning of September 11, 2001.

© NASA

"The world changed today. What I say or do is very minor compared to the significance of what happened to our country today when it was attacked," Culbertson said in a public letter posted after the terror attacks, per the agency.

The astronaut added that it was indeed "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 noted.

"[...] Each year, we pause and never forget. Beyond remembering and honoring the Americans who died that day, NASA also assisted FEMA in New York in the days afterward, and remembered the victims by providing flags flown aboard the Space Shuttle to their families," NASA stated in its Saturday's release.

After 9/11, NASA research programs were demanded for the ground, with the agency collaborating with FEMA to fly sensors over the damaged areas aboard aircraft in search of aerial contaminants, as well as using satellite resources to monitor from above.

In commemoration of the victims, NASA flew over 6,000 4-by-6-inch (10-by-15 cm) flags on Endeavour's December 2001 trip. In the summer of 2002, the flags were handed to relatives.

STS-108 astronauts Mark Kelly, left, and Dan Tani hold commemorative American flags the shuttle Endeavour in December 2001.

© NASA

The agency also used aluminum from the World Trade Center towers that was emblazoned with an American flag on rock abrasion tools for the Mars Exploration Rovers Spirit and Opportunity.

"One day, both rovers will be silent. In the cold, dry environments where they have worked on Mars, the onboard memorials to victims of the Sept. 11 attack could remain in good condition for millions of years," NASA wrote at the time.

This view of an American flag on metal recovered from the site of the World Trade Center towers shortly after their destruction on Sept. 11, 2001, was taken on Mars on Sept. 11, 2011, the 10th anniversary of the attacks on the towers.

© NASA . NASA/JPL-Caltech/Cornell University/Arizona State University