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Primary Batteries are used for several applications in Space, including supplying power during launch, and up until deployment of solar panels. They are used to supply short bursts of power, for example to fire a pyro. Short missions where no energy source is available to charge the battery would use a primary battery as well as applications which require low power for long periods of time, like computer memory.
The earliest use of a battery in an orbital spacecraft was on the Russian Spacecraft, Sputnik which launched on 4th October, 1956. Sputnik 1 used a Silver - Zinc (Ag-Zn) battery which provided power for spacecraft communication and operation. No charge equipment was present on the spacecraft (e.g. no solar panels) so when the battery was exhausted, communication ended. The mission was expected to last for three weeks, but in fact, remained powered for three months. The second Sputnik mission, which was six times larger than the first, also used a (much larger) Silver-Zinc battery, and lasted for five months. Several U.S spacecraft used Ag-Zn batteries including Ranger 3 in which the battery provided main power, and camera power. Mariner 2, another U.S. spacecraft, contained one 40Ah Ag-Zn battery, and was the first successful interplanetary mission to Venus.
Ag-Zn is an aqueous alkaline system with very high specific power and energy (119Wh/kg), but operates over a small temperature range (5°C to 40°C) and is quite expensive due to the use of silver. They are still used in selected applications, such as launch vehicles (rockets) and torpedoes.
The first U.S. spacecraft, Explorer 1, which was first to detect the Van Allen Radiation Belt, used a Zinc - Mercury Oxide (Zn-HgO) Battery. The mission lasted for 3.8 Months and the battery made up approximately 40% of the payload weight. These cells have high volumetric energy density, a very flat discharge profile, and good shelf life, but they are expensive, and exhibit reduced performance below 0°C.
More recent missions have tended towards using lithium based primary batteries due to their much higher voltages than the aqueous alkaline systems, as well as higher specific energy, and energy density. Lithium systems also exhibit much longer storage life capabilities and have larger operational temperature ranges. The limitations of the lithium systems are lower specific power, and that the cells can be dangerous if used incorrectly.
Lithium - Sulphur Dioxide (Li-SO2) batteries have been used in missions such as the Galileo Probe, Genesis, Mars Exploration Rover (MER), and Stardust. In Galileo for example, the battery was used to power all electronics on the spacecraft. It was an atmospheric probe which studied Jupiter and its moons. Li-SO2 batteries have good low temperature performance