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Americans are famously fond of their guns. So it should come as no surprise that a team of NASA scientists has devised a way to \u201cshoot\u201d a modified type of sensor into the soil of an otherworldly body and determine what it is made out of. That is precisely what Sang Choi and Robert Moses from NASA\u2019s Langley Research Center did, though their bullets are miniaturized spectrometers rather than hollow metal casings.\u00a0<\/p>\n
<\/p>\n First, let\u2019s look at the miniaturized spectrometers. Spectrometers have been a workhorse of space exploration for decades. They analyze everything from the surface of Enceladus to stars. However, they almost all use a type of spectroscopy known as Fraunhofer diffraction. Drs. Choi and Moses decided to use a different physical phenomenon in their invention, known as Fresnel\u2019s diffraction.<\/p>\n In Fresnel diffraction, a spectral graph becomes very clear at much smaller distances than those created by Fraunhofer diffraction. Since the necessary distance between a \u201cgrating\u201d and the sensor required by a spectrometer using Fraunhofer diffraction is one of the system\u2019s design constraints, most spectrometers in use today are prohibitively large.<\/p>\n \n