A new sustainable power system for space exploration
In depth

A new sustainable power system for space exploration

The latest rover on its way to Mars is equipped with a new and improved nuclear power system that will last a lot longer than most space exploration missions.

The Perseverance Rover

On June 21st 2020, NASA’s Perseverance Rover took off to Mars from the Kennedy Space Center in Florida, equipped with the latest nuclear power system created by the  Office of Nuclear Energy at the US Department of Energy (DOE).

The Perseverance Rover under construction (Photo: NASA)
The Perseverance Rover under construction (Photo: NASA)

At present (January 2021), Perseverance is on its way to March. It is expected to land on the Jezero Crater on February 18th. Over 5 billion years ago, Jezero was covered by a lake and a river delta. The mission consists of collecting and analyzing the rocks formed in Mar’s humid past in orde to study the possible existence of ancient microbial life. It will also collect rocks and soil samples and leave them on the surface so they can be retrieved during a future mission back to Earth.

The Perseverance Rover is on its way to Mars with a new and improved nuclear power system that will last much more than the systems for most space exploration missions.

El sistema MMRTG

This new power system is known as Multi-Mission Radioisotope Thermoelectric Generator (MMRTG).

Multi-Mission Radioisotope Thermoelectric Generator (Photo: DOE)
Multi-Mission Radioisotope Thermoelectric Generator (Photo: DOE)

The MMRTG in Perseverance works essentially like a nuclear batery: it converts heat from the natural radioactive decay of plutonium-238 into a steady flow of electricity. At the start of Perseverance’s mission, the system will produce approximately 110 watts (similar to a light bulb), and ever year it will go down a few percent.

The MMRTG also charges two lithium-ion batteries, which are used during daily operations, and in cases like scientific activities where the demand temporarily exceeds the usual electrical output levels the system can reach up to 900 watts. It weighs approximately 45 kg and contains 4.8 kg of plutonium dioxide as a heat source. The two batteries weigh a total of 26,5 kg. Each has a capacity of 45 amp-hours.

The MMRTG system works like a nuclear battery, converting heat from the natural radioactive decay of plutonium-238 into a steady flow of electricity.

Long life and optimal temperatures

The MMRTG has an operational lifespan of 14 years, more than enough to provide the necessary energy during the year that Perseverance’s mission on Mars will last. This system not only provides energy to the rover; the extra heat will help keep the robot’s tools and systems at their correct operational temperature.

Artist's representation of Perseverance on the surface of Mars (Photo: NASA)
Artist's representation of Perseverance on the surface of Mars (Photo: NASA)

The MMTG has an operational lifespan of 14 years, more than enough to provide the necessary energy for the year that Perseverance's mission on Mars will last.

Next mission: Dragonfly

DOE’s next MMRTG is set to power the Dragonfly rotorcraft lander mission to explore Titan, Saturn’s largest moon. Since solar energy is not a viable option in Titan’s hazy atmosphere, the MMRTG will play a major role in supplying power to the spacecraft. Dragonfly is scheduled to launch in 2026.

Artist's image of the Dragonfly rotorcraft on Titan (photo: NASA)
Artist's image of the Dragonfly rotorcraft on Titan (photo: NASA)

The MMRTG can provide energy when there is no possibility of using solar power