Space Sci Rev (2008) 135: 293–311 DOI 10.1007/s11214-007-9276-1 Protein Microarrays-Based Strategies for Life Detection in Astrobiology Víctor Parro · Luis A. Rivas · Javier Gómez-Elvira Received: 3 August 2006 / Accepted: 7 September 2007 / Published online: 30 October 2007 © Springer Science+Business Media B.V. 2007 Abstract The detection of organic molecules of unambiguous biological origin is funda- mental for the confirmation of present or past life. Planetary exploration requires the de- velopment of miniaturized apparatus for in situ life detection. Analytical techniques based on mass spectrometry have been traditionally used in space science. Following the Viking landers, gas chromatography-mass spectrometry (GC-MS) for organic detection has gained general acceptance and has been used successfully in the Cassini–Huygens mission to Ti- tan. Microfluidics allows the development of miniaturized capillary electrophoresis devices for the detection of important molecules for life, like amino acids or nucleobases. Recently, a new approach is gaining acceptance in the space science community: the application of the well-known, highly specific, antibody–antigen affinity interaction for the detection and identification of organics and biochemical compounds. Antibodies can specifically bind a plethora of structurally different compounds of a broad range of molecular sizes, from amino acids level to whole cells. Antibody microarray technology allows us to look for the pres- ence of thousands of different compounds in a single assay and in just one square centimeter. Herein, we discuss several important issues—most of which are common with other instru- ments dealing with life signature detection in the solar system—that must be addressed in order to use antibody microarrays for life detection and planetary exploration. These issues include (1) preservation of biomarkers, (2) the extraction techniques for biomarkers, (3) ter- restrial analogues, (4) the antibody stability under space environments, (5) the selection of unequivocal biomarkers for the antibody production, or (6) the instrument design and im- plementation. Keywords Planetary exploration · Life-detection instruments · Antibody microarrays · Immunosensors V. Parro ( ) · L.A. Rivas · J. Gómez-Elvira Centro de Astrobiología (INTA-CSIC), Carretera de Ajalvir km 4, Torrejón de Ardoz, 28850 Madrid, Spain e-mail: parrogv@inta.es