US President Joe Biden joined former Presidents Obama, Bush and Clinton as the US and the world solemnly marked the 20th anniversary of 9/11. Video / AP
Twenty years after the September 11 terror attacks that killed nearly 3000 people, Nasa has released a photo from space showing the chilling devastation it had on New York.
In a satellite image provided by the agency, billowing smoke over the Manhattan area can be seen from space after twoof the hijacked planes crashed into the towers of New York City's World Trade Center.
"The attacks of September 11, 2001, were a national tragedy that resulted in a staggering loss of life and a significant change in American culture. Each year, we pause and never forget.
"Beyond remembering and honouring the Americans who died that day, Nasa also assisted FEMA in New York in the days afterwards, and remembered the victims by providing flags flown aboard the Space Shuttle to their families," Nasa wrote in a release.
Astronaut Frank Culbertson, who was aboard the international space station when the attacks on the World Trade Center happened, has also spoken about his experience at what he saw from space.
He was the only American on board the space station and says he began documenting the event in photographs as the station flew over the New York City area.
"The smoke seemed to have an odd bloom to it at the base of the column that was streaming south of the city," Culbertson wrote in a post at the time of the attack.
"After reading one of the news articles we just received, I believe we were looking at [New York] around the time of, or shortly after, the collapse of the second tower. How horrible.
Visible from space, a smoke plume rises from the Manhattan area after two planes crashed into the towers of the World Trade Center. Photo / Nasa
"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 Earth and watching life being destroyed by such wilful, terrible acts is jolting to the psyche, no matter who you are."
After the attack Nasa's science programmes were "called into action", using fly sensors and satellite resources to look at the affected areas on aircrafts and looking for aerial contaminants.
As a mark of respect, Nasa used aluminium recovered from the destroyed World Trade Center towers – with the image of 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 on-board memorials to victims of the September 11 attack could remain in good condition for millions of years," Nasa wrote.
Lastly, in 2011, flags from Florida's Spaceport were sewn into an American Flag – known as "The National 9/11 Flag" – that was recovered near ground zero following the attacks.
