September 18, 2001, September 22, 2001, and September 23, 2001: NASA Conducts Additional Flights to Examine Ground Zero Dust

At the White House’s request, NASA’s de Havilland Twin Otter prop plane, equipped with the AVIRIS unit (see September 12, 2001), conducts additional flights over Manhattan (see 12:00 p.m. September 16, 2001-2:00 a.m. September 17, 2001), collecting data on the chemical composition of the dust and debris that was distributed throughout the city when the World Trade Center’s twin towers collapsed. [St. Louis Post-Dispatch, 2/10/2002]