Viking's biology instruments have completed their search for life on Mars.

Controllers at Caltech's Jet Propulsion Laboratory commanded Viking Lander 2's biology instrument off May 28. The biology instrument in Lander 1 was turned off May 30.

Viking Lander 1's biology instrument began operations July 28, 1976. Lander 2 began searching Martian soil samples last Sept. 11. Both have operated continuously since.

Both instruments worked to depletion of high-pressure helium, nutrients and other consumable. They performed all experiments that the instrument was designed for, and several that hadn't been planned.

Both Viking landers continue to operate in satisfactory manner; all experiments except biology and organic analysis are operating. (Experiments on Lander 2 have been reduced because of the winter cold, but the spacecraft is still operational.) Both orbiters contiuue to operate normally.

Biologists continue to study various combinations of soil and other chemicals in laboratories across the United States in an attempt to duplicate results from the biology instruments on Mars.

Viking is operated for NASA's Office of Space Science by Langley Research Center, Hampton, Va. The mission is controlled from Jet Propulsion Laboratory. G. Calvin Broome is mission director.

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