1. Mission to Ganymede DIFFRACTION CAMERA SEEKING FOR THE MICROORGANISMS’ TRACES ON GANYMEDE Leonid Ksanfomality Space Research Institute RAS, Profsoyuznaya 84/32, 117997, Moscow, Russia ksanf@iki.rssi.ru, Ganymede Workshop, March 5-7, 2013

2. An ongoing problem of space experiments is the conflict between a large volume of scientific information and limited technical capacity of a radio link. Despite a search for hypothetical microorganisms by television microscopy method may be a most productive way, in the case of lander for the study of Jupiter's moons, both the large volume and number of microscopic images makes it problematic due to the huge information ammount to be returned to the Earth. It is expected that the concentration of hypothetical microorganisms in soil or ice will be very low; so much a large part of the transmitted information would be useless. To solve these problems is proposed a DIFFRACTION CAMERA experiment, which uses a new physical principle permitting to find wanted micro- objects automatically and to use the radio link channel for meaningful information only.

3. The method is based on a little-known optical principle, associated with the phenomenon of diffraction. When coherent light falls on a thin layer of the medium (such as a flat micro cuvettes), particles included in it, form diffraction rings on a screen located behind the medium. In the proposed method the screen is a CCD. Diffraction camera runs as a detector of objects, which concentration is low, and determine their position and size using emerging rings. If the laser beam encounters a small obstacle on the micro cuvettes, diffraction patterns occur on the CCD. The resulting image of the rings is not subject for radio transmission, but the location of the rings is used to calculate the coordinates of each heterogeneity particle in the medium (e.g., microorganisms). Image of the cuvettes field for analysis

5. The measurement process consists of two steps. Step 1: to find and check the emerging diffraction rings. The laser beam scans progressively a target. Rings are registered by the CCD 1. Since the angle  =1.22 /  and   R/L (since R << L), the taken distance L = 50 mm provides the first diffraction ring with the radius R = 1.9 mm for an object having the size D = 28 mum, observed at a wavelength λ = 0.9 mum. The range of sizes 0.9- 28 mum corresponds approximately to the averaged size of Earth’ bacteria. The image of the field with detected rings is used for calculation of coordinates of the wanted objects. Scheme of producing of diffraction rings ("Step 1"), and scanning of selected areas of the image based on the analysis of the position of rings ("Step 2").

6. Then the step 2 starts. The LEDs light and diagonal mirror are introduced into the measurement channel. Laser and CCD 1 are disabled. The lens and CCD 2 operate. The LED lights and mirror are attached to the flexible plate which avoids mechanical sliding or rotation. LED light illuminates the cuvettes. The lenses built image of the cuvettes on the CCD 2. Only small selected areas of the image of the micro cuvettes produced on the CCD 2 are to be scanned. Selected fragments of the micro image are memorized and transmitted by the radio link. Of course, the detected objects not necessarily are bacteria. Would the unit been equipped by the artificial intellect, the images of inclusions of known inorganic nature will not be transmitted. Shown in the figure refers to the protection of a particular project study of Jupiter's moons, located in the radiation belts.

7. Technical characteristics of the diffraction camera depend on the task. For the mission to the moons of Jupiter, according to the conceptual design, the power consumption of the camera is 3 W, and the mass of the device about 0.8 kg. For the example shown above, the file to be only 2 KB (with a software image compression). Literature Born, M. and Wolf, E., Principles of Optics, 6-th edition, Pergamon Press Ltd., 1980, pp.370-458. Ganymede Workshop, March 5-7, 2013

8. If the microflora on Ganymede exists, it should be present inevitably as traces in solid ice of the surface, in inactive, or, may be, in a latent form. Liquid solution in cracks is delivered to the surface and gets solid. It is supposed that a pattern will be studied in a liquid form having a low concentration of the microflora traces. An experiment with a usual microscope requires a huge amount of the information to be returned, that is impossible for technical reasons. To solve the problem the DIFFRACTION CAMERA experiment is proposed.