[5][6] The rover could have been the first mission since the Viking program landers of the 1970s to specifically look for the chemistry associated with life (biosignatures), such as carbon-based compounds along with molecules involving both sulfur and nitrogen.

The AFL payload was to attempt to minimize any conflicting positive detection of life by including a suite of instruments that provide at least three mutually confirming analytical laboratory measurements.

[3] For the purpose of discerning a reasonable estimate on which to base the rover mass, the conceptual payload was to include:[1] It was suggested that the Astrobiology Field Laboratory use radioisotope thermoelectric generators (RTGs) as its power source, like the ones to be used on the Mars Science Laboratory.

Though the AFL science justification did not include a pre-definition of potential life forms that might be found on Mars, the following assumptions were made:[1] Within the region of surface operations, identify and classify Martian environments (past or present) with different habitability potential, and characterize their geologic context.

Quantitatively assess habitability potential by:[1] It is fundamental to the AFL concept to understand that organisms and their environment constitute a system, within which any one part can affect the other.