'Kilopower' Could Power a Mars Colony and Deep Space Missions

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Science fiction writer Douglas Adams said it best — “Space is big. Really big. You just won’t believe how vastly, hugely, mind-bogglingly big it is.” Getting from one point to another takes a very, very long time, especially with our present technology. Right now, the closest neighboring star system is roughly 4.24 light years away. With our current spacecraft, it would take more than 81,000 years to reach it!

Unfortunately, NASA doesn’t currently have a solution for shortening that journey in any meaningful way, but the space agency might just have a way to power an interstellar mission. What is the Kilopower Project, and what could it mean for the future of spaceflight?

Power Problems and Spacecraft Design
Powering a spacecraft once you get a few million miles from the nearest electrical outlet can be tricky — fuel runs out, batteries discharge, and with no backup, you're left drifting in the cold emptiness of space, without power, oxygen, or heat. Even solar power, which has been used to charge up probes as far away as Jupiter and Saturn, gets less and less useful the farther you get from the sun.

Nuclear power has been touted as an option, especially for long space voyages, but it has its problems — most glaringly the fact that we've mostly run out of the specific type of plutonium that powers traditional nuclear reactors in space. Still, NASA has been researching safe, efficient ways to utilize nuclear power for decades.

Older spacecraft, like the two Voyager probes, use a form of thermoelectric generator that converts heat from decaying plutonium. Even the Curiosity Rover, which is roaming the surface of Mars, is equipped with a thermoelectric generator, as well as some solar panels to supplement its power needs. Curiosity doesn't need much power, though — it only uses about 200 watts. Modern spacecraft ferrying earthly explorers will require much more. That’s where the Kilopower Project comes in.

Introducing the Kilopower Project
A reliable power source is essential to survival in space — or on any currently uninhabited planet. The Kilopower project utilizes nuclear fission, with small portable reactors that can handle any rough or unfriendly environment. Prototypes are currently being tested, and if they are successful, they will be able to handle everything from the cold vacuum of space to the dust storms of Mars.

Rather than using plutonium, like previous spacecraft reactors, the Kilopower devices run on uranium. Each unit is designed to create about 10 kilowatts (10,000 watts) of power, and if more is needed, multiple Kilopower reactors can be daisy-chained together. For comparison, the average home in the United States uses roughly 10,700-kilowatt hours a year, roughly equivalent to using one Kilopower reactor for about 42 days. Power needs for human habitats on other planets would be higher, due to the need to produce things like oxygen, heat and water, but many Kilopower reactors could efficiently meet the needs of a human colony on the Moon or Mars.

This is a much more efficient energy source than any solar panels, especially on planets like Mars, where dust storms can last for months at a time, completely blotting out the sun.

It’s not a perfect solution — there are risks. The most consequential are present during launch, ascent, and when the vehicle enters orbit. That said, those are the riskiest points for any space vehicle launch, no matter its power source. The biggest concerns with getting these nuclear-powered reactors into orbit are what would happen if the vehicle exploded in transit — would there be radioactive material raining down on the populace? It has already happened once. A satellite carrying the SNAP-9A plutonium system failed during launch in 1964. The satellite burned up during re-entry, releasing plutonium that hung in the air, approximately 120,000 feet above sea level, for many months afterward.

NASA isn't unaware of these risks. When the Curiosity probe was launched in 2011, they estimated the cost of a nuclear decontamination if the plutonium that powers the probe were to fall to earth during launch. Cleaning farmland would cost more than $250 million per square mile, while cleaning up a spill in urban areas would cost upwards of $1.5 billion per square mile.

The Future of Space Travel
So, what does this new portable nuclear reactor mean for the future of space travel?

If the prototypes work, it could become the power source that supports habitats on the Moon, Mars, and other bodies in our solar system. It could also fuel long-range spacecraft, both manned and unmanned, to help us explore our solar system and make our way further out into the galaxy. Even if they don’t fuel the spacecraft themselves, these reactors are designed to be stored in transit and assembled once they reach their location.

One of the best parts of the Kilopower design is its intended purpose of using local resources once it reaches its destination. Initially, it will be equipped with a dense core of Uranium-235 about the size of a roll of paper towels. This is estimated to provide power for roughly 10 years. Because this element is relatively abundant on the inner planets and may also exist in the asteroid belt, the Kilopower reactor could be resupplied, allowing a colony to fully self-sustain. This way, once the initial set up is complete, we don't have to worry about sending additional supplies or fuel from Earth.

Right now, traveling even to our closest interstellar neighbor is out of reach, but as technology continues to develop it's entirely possible that Kilopower reactors will fuel our first interstellar trips. We just have to keep reaching for the stars, and it won't be long before we're actually among them.

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