Page:Concepts for detection of extraterrestrial life.djvu/23

 CHAPTER III

The detection of life by looking for it sounds elementary; however, this seemingly simple technique is extremely complex and involves numerous technical problems. The usefulness of a visual method lies in the extensive background of classical terrestrial biological observation from the macrocosm to the microcosm. In addition, the morphological approach does not depend upon assumptions concerning the nature of extraterrestrial biochemistry. Certain structural attributes, with varied degree of elaboration and application, are not expressions of particular specific form, but of life itself.

A television (vidicon) microscope for planetary exploration has been suggested by Dr. Joshua Lederberg of Stanford University. The investigation of this idea is being carried out in his Instrument Research Laboratory and in Dr. Gerald Soffen’s laboratory at the Jet Propulsion Laboratory of the California Institute of Technology. These groups are assessing the problems of using the microscope as an instrument of life detection.

Terrestrial atmosphere and soil contain a multitude of viable or moribund microscopic organisms,. [sic] Bacteria, algae, fungi, protozoans, and diatoms are commonly found. Fragments of organisms and fossil forms are also frequently among the components. Special parts of organisms, such as seeds, pollen grains and spores, comprise an important fraction because of their capability of surviving rigorous environmental conditions.

Recognition and identification of micro-organisms by microscopy is often difficult and uncertain; however, in many cases, characteristic morphology is highly indicative and sometimes conclusive. Specific form, size, symmetry, optical properties, surface features, pigmentation and intricate internal architecture are among those typical details which have made the microscope useful. In addition to conventional use, the microscope may be extended to carry out microspectrophotometry, microhistochemistry and microfluorometry, which 13