NASA Releases Image of Aftermath of 9/11 Showing Smoke Plume From Space

This year marks the 21st anniversary of the deadly 9/11 terror attacks in the U.S., which claimed the lives of nearly 3,000 people.

September 11th was marked by a speech from President Joe Biden at the Pentagon, which was also hit in the attacks, and First Lady Jill Biden spoke from the site in Pennsylvania where a plane that was being flown by hijackers crashed.

"Twenty-one years later, we keep alive the memory of all the precious lives stolen from us at Ground Zero, in Shanksville, Pennsylvania, and at the Pentagon," Biden said via the president's official Twitter account. "To the families and loved ones who still feel the ache, Jill and I hold you close in our hearts. We will never forget."

Former presidents shared tributes online, including George W. Bush, Bill Clinton and Barack Obama.

NASA shared a poignant image of the aftermath of the attacks, captured by an astronaut on the International Space Station (ISS).

Expedition 3 Commander Frank Culbertson took photos of New York as the ISS flew overhead. The space agency posted a series of images, along with a video and Culbertson's reflections on the attacks, to its website on Sunday.

NASA explained Culbertson was the only American aboard the ISS: "As soon as he learned of the attacks, he began documenting the event in photographs because the station was flying over the New York City area.

"He captured incredible images in the minutes and hours following the event. From his unique vantage point in space, he recorded his thoughts of the world changing beneath him."

One image shows the smoke plume above Manhattan "visible from space," believed to have been taken after the twin towers of the World Trade Center collapsed.

Speaking about his vantage point of the horror unfolding below, in a letter dated September 11, 2001, Culbertson said: "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..."

The next day he added: "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.

"And the knowledge that everything will be different than when we launched by the time we land is a little disconcerting."

U.S. airspace was closed for several days following the attacks, as the Federal Aviation Administration grounded all flights.

In the hours following the attack, NASA assisted in other ways, as the site noted: "NASA science programs were called into action after Sept. 11, 2001, as the agency worked with FEMA to fly sensors over the affected areas on aircraft looking for aerial contaminants and used satellite resources to monitor from above."

Some 2,996 perished in the attacks, with 2,750 dying in the attacks in New York, 184 at the Pentagon and 40 in Pennsylvania, when passengers overpowered the hijackers and downed the plane in a field near Shanksville, Pennsylvania.

Reflecting on the anniversary, Biden said in a statement on Sunday: "Through all that has changed over the last 21 years, the enduring resolve of the American people to defend ourselves against those who seek us harm and deliver justice to those responsible for the attacks against our people has never once faltered."

Referencing a recent U.S. drone strike that killed a member of Al-Qaeda, and the one which killed Osama bin Laden in 2011, he continued: "It took 10 years to hunt down and kill Osama bin Laden, but we did.

"And this summer, I authorized a successful strike on Zawahiri—the man who bin Laden was his deputy at 9/11 and was the leader of Al-Qaeda—because we will not rest. We'll never forget, we'll never give up and now Zawahiri can never again threaten the American people."