Scientists at NASA explain that unmanned spacecraft traveling away from the sun to explore the outer planets of the solar system are powered by nuclear energy, specifically Plutonium-238 built into a Radioisotope Thermoelectric Generator (RTG).
Elements such as Uranium and Plutonium are considered “radioactive” due to an imbalance of protons and electrons. The process of radioactive decay occurs as an atom of these elements naturally seeks to stabilize itself by releasing subatomic particles into the environment.
Alpha, beta, and dangerous gamma radiation are emitted as heat energy that can be converted into electricity within the generator.
Deep Space Network
The Jet Propulsion Laboratory in California is NASA’s home base for unmanned space travel. Scientists of the JPL oversee missions such as the Opportunity and Curiosity rovers on Mars, the Juno spacecraft orbiting Jupiter, and the Cassini mission exploring Saturn.
The Jet Propulsion Labs are also where NASA’s Deep Space Network is managed. The “network” is a series of dish-shaped antennas at three strategic locations around the globe; California, Madrid, and Australia. The stations are spaced approximately 120 degrees longitude apart from each other, ensuring that as the earth rotates there is a continual connection with NASA spacecraft wherever they are in the solar system.