Space probes with digital holographic microscopes could be used to detect alien organisms

Satruns icy moon Enceladus has a global subsurface ocean with the necessary ingredients to harbour life as we know it on Earth. Cassini, the constant companion of Saturn for over thirteen years observed plumes of water erupting from a region near the south pole of Enceladus, known as the tiger stripes. Cassini, unfortunately did not have the equipment necessary to directly look for life when it made a close flyby over the icy moon. In fact, no probe since NASAs Viking program in the late 1970s has actively looked for living organisms.