VL1/VL2 MARS LABELED RELEASE V1.0

The Labeled Release (LR) instrument on each Viking Lander operated throughout the Primary Mission and continued into the Extended Mission. The basic analysis cycle for the Labeled Release experiment was to deliver a sample of martian soil to one of four test cells, seal the cell and moisten the soil with an aqueous solution of carbon-14 labeled organic media. A second nutrient injection was typically done about 7-8 Mars days after the first injection. The test cell was continuously monitored for the release of radioactive labeled gas as an indicator of heterotrophic metabolism. Viking Lander 1 (VL1) conducted four analysis cycles with two nutrient injections for cycles 1, 2, and 4 and three injections for cycle 3. Viking Lander 2 (VL2) conducted five analysis cycles. The first four cycles had two nutrient injections each, and the fifth cycle had one injection [LEVIN&STRAAT1976B