Page:Concepts for detection of extraterrestrial life.djvu/25

Rh which offers a unique solution to the “deposition” of a sample for optical examination (fig. 4). An aerosol sample is injected into the plane of focus of the microscope through an orifice in the condenser lens. The image is transmitted by vidicon. The lens system observes a 100-μ field with 0.5-μ resolution. The vidicon picture, when telemetered to Earth, would require a great deal of data transmission; it might take hours to send a single picture. When more power and larger antennas are available, and with special data handling techniques, this time may be reduced significantly.

A more complex idea under development employs spectral and spatial scanning as a criterion for the selection of objects of interest. Specific ultraviolet absorption of particles is carried out by scanning microspectrophotometry. This has been developed to include the fluorometric capability of detecting the primary fluorescence of native compounds and fluorescence due to products formed by specific reactants. The scanning technique is also being investigated for use with biological stains.

Other areas being explored are automatic focusing, changes in magnification, the use of more sensitive imaging devices, and improved sample preparation to remove the inorganic fraction.