September 17, 2001-September 19, 2001-: US Geological Survey Collects Dust Samples near Ground Zero

US Geological Survey (USGS) geophysicists Gregg Swayze and Todd Hoefen fly to New York City to get calibration data from the ground that will supplement the data collected by AVIRIS (see 12:00 p.m. September 16, 2001-2:00 a.m. September 17, 2001). They collect 35 dust samples from a variety of locations around Ground Zero including window ledges, flower pots and car windshields. While “AVIRIS offers a bird’s-eye view…,” Roger Clark, a USGS astrophysicist, later explains to the St. Louis Post-Dispatch, “The ground samples… gave us up-close, specific information on specific points.” On September 19 they send their data to the USGS office in Denver over the Internet. The next day, scientists will begin conducting a variety of tests on the samples (see September 20, 2001). [St. Louis Post-Dispatch, 2/10/2002; St. Louis Post-Dispatch, 2/10/2002]