Is there life on Mars? That question has been on the minds of scientists and lay people alike for a very long time. Nineteenth century Italian astronomer Giovanni Schiaparelli claimed to have observed linear patterns on the planet’s surface that he called canali, unfortunately mistranslated into English as canals, that led to a belief that they were the products of intelligent beings on Mars. Although that concept fell out of favor among scientists in the 20th century, the idea of sentient beings on Mars persisted in popular culture. With little concrete information about surface conditions on the Red Planet, even some scientists into the 1960s believed Mars might be hospitable to at least some form of primitive extraterrestrial life.
The biology package consisted of four experiments. The gas chromatograph mass spectrometer was designed to look for any organic compounds that might be present in Martian soil samples. The gas exchange experiment looked for gases given off by a sample of Martian soil incubated in a mix of organic and inorganic nutrients, essentially looking for products of metabolism by any microorganisms. In the labeled release experiment, a drop of a nutrient solution tagged with a 14C label was placed on a soil sample and the air monitored for the release of any 14CO2, a sign of metabolism. The pyrolytic release experiment placed 14C labeled gasses in a chamber with Martian soil, and after a few days of incubation the soil was baked and detectors looked for signs of any labeled gas that would be evidence that organisms in the soil had incorporated them in a process such as photosynthesis. Each lander also carried a remote sampler arm to take soil samples and deposit them into the biology instruments.