Viking Lander

Viking Lander

The Viking lander extends human capabilities to other and alien landscapes. By some standards, it is about as smart as a grasshopper; by others, only as intelligent as a bacterium. There is nothing demeaning in these comparisons. It took nature hundreds of millions of years to evolve a bacterium, and billions to make a grasshopper. With only a little experience in this sort of business, we are becoming fairly skilful at it. Viking has two eyes as we do, but they also work in the infrared, as our do not; a sample arm that can push rocks, dig and acquire soil samples; a kind of finger that it puts up to measure wind speed and direction; a nose and taste buds, of a sort, with which it senses, to a much higher precision than we can, the presence of trace molecules; an interior ear with which it can detect the rumbling of marsquakes and the gentler wind-driven jiggling of the spacecraft; and a means of detecting microbes. The spacecraft has its own self-contained radioactive power source. It radios all the scientific information it acquires back to Earth. It receives instructions from Earth, so human beings can ponder the significance of the Viking results and tell the spacecraft to do something new.

But what is the optimum way, given severe constraints on size, cost and power requirements, to search for microbes on Mars? We cannot – at least as yet – send microbiologists there. Carl Sagan once had a friend, an extraordinary microbiologist named Wolf Vishniac, of the University or Rochester, in New York. In the late 1950’s, when they were just beginning to think seriously about looking for life on Mars, he found himself at a scientific meeting where an astronomer expressed amazement that the biologists had no simple, reliable, automated instrument capable of looking for microorganisms. Vishniac decided he would do something about the matter.

Small devices lead to great discoveries (quotations from Megan Jorgensen). Image: by © Megan Jorgensen (Elena)

He developed a small device to be sent to the planets. His friends called it the Wolf Trap. It would carry a little vial of nutrient organic matter to Mars, arrange for a sample of Martian soil to be mixed with it, and observe the changing turbidity of cloudiness of the liquid as the Martian bugs (if there were any) grew (if they would).

The Wolf Trap was selected along with three other microbiology experiments to go aboard the Viking landers. Two of the other three experiments also choose to send food to the Martians. The success of the Wolf Trap required that Martian bugs like liquid water. There were those who thought that Vishniac would only drown the little Martians. But the advantage of the Wolf Trap was that it laid no requirements on what the Martian microbes must do with their food. They had only to grow. As the other experiments made specific assumptions about gases that would be given off if taken in by the microbes, assumptions that were little less than gossips.

The National Aeronautics and Space Administration, which runs the United States planetary space program, is subject to frequent and unpredictable budget cuts. Only rarely are there unanticipated budget increases. NASA scientific activities have very little effective support in the government, and so science is most often the target when money needs to be taken away from NASA. In 1971 it was decided that one of the four microbiology experiments must be removed, and the Wolf Trapp was off loaded. It was a crushing disappointment for Vishniac, who had invested 12 years in its development.