In the high desert of Nevada, Elizabeth Silber watched NASA’s Sample Return Capsule from OSIRIS-REx descend into Earth’s atmosphere on Sunday, but unlike most scientists, she wasn’t there for the asteroid rocks.
Silber, a physicist at Sandia National Laboratories, is working with researchers from Sandia and Los Alamos national laboratories, the Defense Threat Reduction Agency, TDA Research Inc., the Jet Propulsion Laboratory, the University of Hawaii and the University of Oklahoma in a campaign to record and characterize the infrasound and seismic waves generated by the capsule as it moved through Earth’s atmosphere at hypersonic speed, about 26,000 miles per hour. This was the largest observational campaign of any hypersonic event in history, and Silber hopes the data will improve scientists’ ability to use infrasound to detect meteoroids and other objects moving at hypersonic speeds.
Scientists currently use infrasound, a low-frequency sound wave that is generally inaudible to humans, to detect and observe volcanic activity, earthquakes and explosions. Silber said infrasound can also be observed when meteoroids enter Earth’s atmosphere, but atmospheric conditions like wind can distort the signal, and there’s usually relatively little information available about the incoming meteoroid to help with data analysis.