Fusion energy has been the “future” for decades, with promises of unlimited clean power and spaceships to the stars recurring cultural themes since the dawn of the Nuclear Age.

Fusion power has been “30 years away and always will be,” since the 1950’s due to the sheer complexity and number of technological barriers involved.

Yet numerous recent breakthroughs have raised public awareness of fusion power and its potential to revolutionize human society.

Space exploration is greatly impacted by these advances in fusion power. Perhaps no one has put it as succinctly as the University of Washington Aeronautics & Astronautics Department:

“Fusion energy is, in principle, the only conceivable source of energy for rapid, efficient, rocket space travel to Mars, the outer planets, and nearby stars, if the payloads are heavy and/or designed to carry humans.”

Exploring the Solar System will be the most transformative process our species has ever undertaken and will profoundly alter our civilization.

Harvesting asteroids will explode the size of the human economy, with some valued in the trillions of dollars. Technological spinoffs will reverberate throughout the rest of society offering advances in healthcare, construction, and manufacturing.

NASA may finally answer that most fundamental question, “Are we alone?” while we establish new habitats that will ensure the survival of humanity in the event of some future cataclysm, human or natural.

Widespread deployment of fusion energy for both propulsion and power generation is the only way this future will come to exist.

The general public may think space fusion applications are pure fantasy, something for sci-fi novels and NASA dreamers. Yet this article will survey the activity happening at a number of companies developing space fusion applications right now.

With more than 30 ground-based private fusion energy projects open to investment it’s clear this future is very much under active development. This article is *not* a detailed dive into the complex physics or engineering behind developing fusion energy in space, but an overview of the major players and the paths they are seeking to chart.

NASA’s Role

NASA has played a significant role nurturing the early research and development efforts around space fusion power, and has ties to many of the companies you are about to meet.

NASA has been flirting with the idea of space fusion since the 1990s, and has sponsored research at the Marshall Space Flight Center, the Glenn Research Center, the University of Maryland, the University of Washington, and the University of Alabama, just to name a few.

*Concept fusion engine from a 2018 NASA sponsored research proposal. Source:* *NASA*.

The SBIR/STTR program facilitates cutting-edge research from industry, and NASA has a unique combination of heft and utility when pushing for powerful new energy sources in space.

NASA can also serve as a facilitator between other branches of the sprawling federal government, for instance a 2021 meeting on space fusion applications convened with DARPA, ARPA, and the Department of Defense.

The Companies:

Below is a tour of some (not all) of the companies currently investing in space fusion power and propulsion systems.

Helicity Space

Flavor of Fusion: Magneto-Intertial Fusion (Helicity Drive)

Location: Berkeley, California

Year Founded: 2018

Helicity Space was founded in 2018 by the trio of Dr. Stephane Linter, Marta Calvo, and Dr. Setthivoine You, and their Advisory Board includes Dr. Alan Stern of New Horizons/Pluto exploration fame. The company works extensively with Caltech, the University of Maryland, and the Department of energy on their work.

*Helicity founding team Source:* *https://www.helicityspace.com/*

Their Helicity Drive is a “novel magneto-inertial fusion concept designed for a fusion space propulsion system,” (Source: Dr. Setthivoine You, AIAA Propulsion and Energy 2020 Forum).

This simplified pulsed fusion system would potentially be much smaller than other proposed systems, offering numerous advantages in terms of development and adoption. This in-depth video by Dr. You and this one by Dr. Stern are highly recommended for those looking for an in-depth physics & engineering break-down of the system.

As of February 2023 the company had raised at least $3.5 million in their latest seed round and has been quite public with their push for fusion power, speaking at conventions and conducting other outreach.

Pulsar Fusion

Flavor of Fusion: Direct Fusion Drive

Location: : Bletchley, United Kingdom

Year Founded: 2011

Pulsar Fusion is the brainchild of Richard Dinan and James Lambert, a continuation of Dinan’s leadership of Applied Fusion Systems. The company built Europe’s largest electric propulsion engine and has received multiple awards from the UK government to build out various nuclear-related technologies.

Pulsar Fusion specializes in smaller Direct Fusion Drive reactors specifically designed for rockets. Their modeling shows a rocket capable of sending a spacecraft weighing 1,000 kg to Pluto in 4 years. For reference NASA’s wildly successful New Horizons probe weighed less than half of that and took over 9 years to reach Pluto.

*Prototype image of the Pulsar Direct Fusion Drive. Source:* *Pulsar Fusion*

Phase 3 testing begins sometime in 2023 and an orbital test is penciled in for 2027.

They are ambitious, driven, and intent on exploring areas of fusion power not yet explored. Their mentality is perhaps best summed up by this quote from Dinan in a 2019 National Geographic article:

“We’re either this cancerous little species that just sits on the planet and consumes all its resources, or we are a species that is destined to transition into the stars. And if we are ever going to leave our solar system, we need fusion. We aren’t going to get to Alpha Centauri by setting things on fire.”

Princeton Satellite Systems

Flavor of Fusion: Princeton Reverse Field Configuration

Location: Plainsboro, New Jersey

Year Founded: 1992

Princeton Satellite Systems was founded in 1992 by Michael Paluszek, a prolific satellite engineer who spent the next 31 years building a small but powerful player in the space fusion ecosystem.

Partnering with the Princeton Plasma Physics Laboratory they’ve developed a Direct Fusion Drive based on technology developed by PPPL’s Dr. Sam Cohen, and their work has been supported by numerous NASA NIAC and Department of Energy ARPA grants. A breakdown of their support reveals almost 40 grants over the years for almost $11 million, largely from NASA and the Department of Defense.

*A mission concept for a Direct Fusion Drive system capable of mining the outer solar system. Source:* *Princeton Satellite Systems*

NASA is specifically interested in a fusion-powered Pluto mission concept developed by Stephanie Thomas, now the Vice-President at Princeton Space Systems. They also offer a Fusion Energy Toolbox to assist in modeling various fusion engines and their potential deep space mission profiles.

Princeton Space Systems has been a mainstay in the space fusion business for many years and that is highly unlikely to change in the years ahead.

NearStar Fusion

Flavor of Fusion: Hypervelocity Gradient Field Fusion

Location: Chantilly, Virginia

Year Founded: 2021

NearStar Fusion is a relatively recent addition to the space fusion scene with an experienced team and an innovative design.

NearStar’s spacecraft design utilizes their Hypervelocity Gradient Field Fusion reactor, a concept historically rooted in NASA but with the firm adding their own specialities in hypervelocity launch technology and plasma jet research.

In this system a canister of deuterium-tritium gas is fired via rail-gun into an intense series of compressive magnetic fields, generating a fusion reaction. The resulting explosion is turned into highly efficient fuel exhaust for spacecraft propulsion.

*Prototype image of NearStar’s fusion spacecraft in the outer Solar System. Source:* *NearStar*

This reactor is rooted in proven concepts and technologies, which NearStar hopes provides efficiencies in cost and production. This highly informative video from NearStar’s Chris Faranetta offers an amazing insight into their vision.

University of Washington/Dr. John Slough/MSNW/Helion Energy

Flavor of Fusion: Pulsed Magneto-Inertial Fusion, Fusion Driven Rocket

Location: Seattle, Washington

Year Founded: ?

One of the most prolific fusion energy research networks is located at University of Washington and includes the research & development combo of MSNW/Helion Energy, notably the fusion rocket research of Dr. John Slough and David Kirtley.

The network has been explained by Kirtley as “the University of Washington is where the basic scientific research is done. MSNW LLC is for the SBIR and other grant work and to prove out work that could potentially be commercialized. Helion Energy is for the commercial venture funded nuclear fusion development.” (Source: Brian Wang, NextBigFuture 2015)

MSNW has been the recipient of a number of SBIR/STTR grants over the years, some of which explored the Fusion Driven Rocket concept. The Fusion Driven Rocket is a:

“Revolutionary approach to fusion propulsion where the power source releases its energy directly into the propellant, not requiring conversion to electricity. The propellant is rapidly heated and accelerated to high exhaust velocity (> 30 km/s), while having no significant physical interaction with the spacecraft thereby avoiding damage to the rocket and limiting both the thermal heat load and radiator mass.” (Source: NASA)

The final summaries from the NASA NIAC Phase I & Phase II programs in the early 2010’s are well worth the read for those interested in a detailed breakdown of the engine and the physics behind it. There is also this incredible behind-the-scenes tour of the Helion reactor with David Kirtley, courtesy of the @RealEngineering channel.

Their Earth-based power plant technology is progressing quickly, with Kirtley hopeful for electricity production from their 7th generation machine in the mid-2020s. It remains to be seen how this progress will impact their space-based proposals, but it’s clear the University of Washington network is a dynamic source of progress in solving the riddle of fusion energy.

Rocketstar/Rhea Space Activity/Miles Space

Flavor of Fusion: Boron Enhanced Electric Propulsion

Location: New York, NY/ Washington D.C.

Year Founded: 2022?

One of the newest space fusion efforts is a BEEP (Boron Enhanced Electric Propulsion) engine under development by a consortium of Rocketstar, Rhea Space Activity, and Miles Space. Rocketstar was awarded two Air Force AFWERX SBIR grants in 2022 for “Hyper-efficient p-B Enhanced Fusion Thruster for Satellite and Space Vehicles,...(an) innovative p-B enhanced ConstantQ plasma thruster, a highly fuel and cost efficient propulsion system for space vehicles and satellites.”

These awards were a product of the company’s Phase I success generating aneutronic fusion, and the Phase II awards will allow them to advance their design and begin quantifying thrust output.

Demonstrating the importance of the work, the “The USSF Space Systems Command (SSC) has identified a need for high power, high thrust electric propulsion systems in the 14kW, 500mN class to provide overwhelming maneuvering capability to future cislunar USSF operations,” which is a capability gap Rocketstar and its’ partners are developing fusion engines to fill.

What the Future Holds

The future of space fusion remains uncertain, but certainly no one can call it static or uninteresting. These companies are pushing the boundaries of technology and our understanding of physics to surmount one of the greatest challenges humanity has ever faced: harnessing the power of the Sun to explore the Solar System and beyond.

The fusion energy movement is gaining significant traction in society. President Biden’s FY 2024 budget proposal includes $1 billion to push forward fusion power research, an unprecedented demonstration of interest in and commitment to fusion from the US Federal Government.

While fusion politics have gotten dicey in DC in the past, there is no indication of any such rancor this time around with both Democrats and Republicans speaking favorably on fusion power in recent years.

There is also bi-partisan agreement on fusion energy among the American public, with roughly equal share of Democrats (+15%) and Republicans (+22%) having a favorable view of nuclear fusion energy. It is also notable how much less polarized this opinion is when compared with other energy sources such as coal, oil, wind, and solar.

The public overall is fairly modest on fusion, with mid-range ‘favorable’ numbers and among the lowest ‘unfavorable’ numbers.

So the public is generally favorable and there are not any major partisan hurdles on the horizon. Hopefully this indicates a relatively clear path for social acceptance of fusion power and its space-based counterpart.

Not every company in this report will succeed, and the long history of innovation (especially in fusion) would indicate most of them will fail despite their credentials and fervent belief.

Yet if even just one succeeds, it will be one of the most revolutionary engineering achievements in human history. The door to the Solar System will have been kicked wide open and an incredible new chapter of prosperity and discovery will await us.

There are amazing resources such as the Fusion Industry Association and Fusion Energy Base where you can track major historical and current developments in the fusion energy ecosystem.

Regardless of what the future holds it’s clear that space fusion is not a dream. It is a dynamic and rapidly growing industry today, with great strides being made around the globe to finally harness the power of the Sun to send humanity to the rest of the Solar System and eventually the stars.

Patrick Chase is a space writer, political junkie, and lifelong space enthusiast.

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