David Rolbiecki, chief of survey for the Texas Military

David Rolbiecki, chief of survey for the Texas Military Forces (TXMF), instructs Mark Hinojosa, TXMF land survey technician, on the classic practice of geodetic astronomy, or how to obtain accurate measurements of the earth by measuring the sun, moon, and stars. Rolbiecki uses a sextant to obtain these precise measurements, the same tool used by the Lewis and Clark expedition in the early 1800s. Rolbiecki is hoping to use his research to feed the National Geodetic Survey, and ultimately help to improve elevation measurements for the Global Positioning System, or GPS. (U.S. Army National Guard photo by Capt. Martha C. Nigrelle/Released)