Man’s inaugural journey into space was a miraculous triumph but human nature leaves us wanting more. We yearn for new information and deeper travels, but innovations down here on Earth are what will launch us to new heights in space.
Solar energy has sufficed with supporting short distance missions, but engineers have been forced to find an alternative energy source for long distance trips to deep space. That energy source is a radioisotiope thermoelectric generator (RTG), and most recently, a multi-mission radioisotope thermoelectric generator (MMRTG).
What is a Radioisotope Thermoelectric Generator?
An RTG generates electricity through the use of radioactive materials. When these materials decay to become non-radioactive, heat is produced. This heat is what is then converted into electricity by a collection of thermocouples.
These thermocouples are the thermoelectric devices that conduct electricity through closed loops. The trick to creating an electrical current within these thermocouples is establishing a temperature difference between the two kinds of metals within the loop.
Although RTGs are essentially nuclear batteries that utilizes heat to create electricity, they are much safer and more reliable than the nuclear stations and weapons that use the process called fission. Fission is an extremely complex process that actively splits unstable radioactive material, whereas radioactive decay in RTGs is more stable and takes place in a radiation-proof shell that can withstand any mishaps. Engineers are constantly finding methods that will make RTGs completely infallible.
What is a Multi-Mission Radioisotope Thermoelectric Generator?
MMRTGs use the same technology at RTGs, but have been created to endure more extreme environments, such as the surface of Mars, and a wider range of mission types. These generators have been optimized for safety and power levels. They include a flexible, transposable design and generate power in smaller increments than a typical RTG and have a greater lifetime.
Applications in Deep Space
Over the course of more than 4 decades, 27 different space missions have utilized RTGs. By the power of RTGs, the Voyager 1 and Voyager 2 have been collecting and sending data back to Earth from deep space for over 40 years. These spacecrafts were designed to eternally explore the Milky Way and Voyager 1 just recently entered interstellar space.
Most recently, the Mars Science Laboratory launched the Curiosity rover, which is equipped with an MMRTG. Curiosity has been exploring the Gale crater on Mars and needed an MMRTG that could withstand the harsh surface of the planet. This rover is also equipped with a ChemCam TE module developed by II-VI Marlow as a cooling solution for the active remote-sensing device that uses laser pulses to vaporize materials and CCD spectrometers to analyze atom activity. II-VI Marlow Industries 2-stage thermoelectric (TE) module is the thermoelectric cooling unit for ChemCam’s spectrometers.
RTGs and MMRTGs in the Future
NASA plans on launching a similar rover to Curiosity in their Mars 2020 mission. This mission will address the longstanding question of potential and past life on mars. Additionally, NASA is working on finalizing their Dragonfly concept for the New Frontiers mission, which would launch an MMRTG-powered drone-like copter onto Saturn’s moon, Titan.
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