fireman@tippy.uucp (03/16/89)
Reprinted from "NASA Tech Briefs," February, 1989. "This conceptual device would scan automatically, without costly aiming or stablizing devices." - NASA's Jet Propulsion Laboratory, Pasadena, California A proposed imaging probe would descend through the atmosphere of a planet, obtaining images of the ground surface as it travels. The probe could be released from an aircraft over the Earth or from a spacecraft over another planet. The probe would have a body and a single wing shaped like much like a samara - a winged seed like those of maple trees. It would therefore rotate as it descends, providing a panoramic view of the terrain below. The probe would radio the image obtained by its video camera to the aircraft or spacecraft overhead. The probe would be simple and inexpensive. It would contain no moving parts and would need no fuel or power for scanning, because its panning motion would be imparted by aerodynamic forces. Several such probes could provide comprehensive, detailed maps of a region without the complexity of horizontal travel on the surface or through the atmosphere. The wing would be propeller shaped and would be pitched for the desired rate of descent and rotation. The camera (or radar) would be mounted on the lower part of the probe at a fixed angle with the repect to the spin axis. The field of view of the camera lens would determine the required amount of overlap of the image on successive rotations; a wider angle would cause more - and earlier - overlap. The resolution of the image would increase gradually as the probe approaches the surface. The upper surface of the wing could carry solar-cell panels, if necessary, to supply power to the camera and transmitter. The transmitting antenna would be embedded in the probe. The wing could also a Sun sensor to furnish data on orientation and spin to aid in subsequent processing of the images. (Image processing would be required to remove effects due to nutation and wind drift.) A second wing, like that on certain seeds, could be added to slow the descent and reduce nutation. [This work was done by James D. Burke of Caltech for NASA's Jet Propulsion Laboratory.]