The feasibility of immunological detection using antibodies as an approach to detect and study alien life forms is examined. The latter could either mean alternative forms of life on planet Earth or extraterrestrial life. As a detection reagent for biological substances, antibodies have the advantage of being conformational, rather than sequence-dependent. Their high affinity to cognate antigens allows detection at picomolar levels. Antibodies could serve both as tools for detection as well as for the concentration of samples. Panels of highly specific antibodies could be made against a plethora of natural or synthetic biomarkers, for example stereoisomers of amino acids, nucleotide analogues, lipids, polysaccharides and polycyclic aromatic hydrocarbons. With detection reagents efficiently packaged and miniaturized as immunosensor chips in analytical panels, antibody microarrays could serve as the first line of detection and identification of biological remnants in situ during exploratory missions. Specific antibodies could also be used for affinity concentration of possible biomarkers obtained from sample return missions. Furthermore, antibodies raised against any alien biological samples could be the first specific probes made for further detection of, or investigations on, alien biology.