Budget Docs Show Pentagon Aims To Loft Particle Beam Anti-Missile Weapon Into Space In Four Years

After three decades, the Pentagon is betting big on their belief that a dream of the Star Wars initiative may now be closer to a practical concept.

Los Alamos National Laboratory via Aerospace Projects Review

The Missile Defense Agency has offered new details about plans to develop a science fiction-sounding space-based neutral particle beam weapon to disable or destroy incoming ballistic missiles. The goal is to have a prototype system ready for a test in orbit by 2023, an ambitious schedule to demonstrate that the technology has progressed to a more useful state from when the U.S. military last explored and then abandoned the concept nearly three decades ago.

The U.S. military’s budget request for Fiscal Year 2020 asks for $34 million in funding for the neutral particle beam program, or NPB, according to documents released on Mar. 18, 2019. The Missile Defense Agency (MDA) wants a total of $380 million through 2023 fiscal cycle for development of the directed energy weapon. Defense One, citing unnamed U.S. officials, had been first to report the existence of the plan on Mar. 14, 2019. It’s also worth noting that Congress set out a goal of testing of at least one space-based missile defense system prototype by 2022 and the deployment of “an operational capability at the earliest practicable date” in the annual defense policy bill for the 2018 Fiscal Year.

MDA included the new-start NPB program in a larger line item called “Technology Maturation Initiatives,” which also includes requested funding for the development of laser weapons and advanced airborne sensors. It does not expect to ask for any more funds for the particle beam system through this account in Fiscal Year 2024, which would indicate plans to move it into its own dedicated funding stream at that time.

“The NPB provides a game changing space-based directed energy weapon capability for strategic missile defense,” MDA’s latest budget request says. “The NPB is a space-based, directed energy capability for homeland defense, providing a defense for boost phase and mid-course phase” of a ballistic missile’s flight.

A staple in science fiction, particle beam weapons are grounded in real science. At its most basic, an NPB requires a charged particle source and a means of accelerating them to near-light speed to create the beam itself.

An extremely rudimentary graphic showing the components of a neutral particle beam system.

When this beam of charged particles hits something it produces effects similar to that of laser, namely extreme heat on the surface of the target capable of burning a hole through certain materials depending on the strength of the weapon. If the particles are not sufficently powerful to destroy something such as a missile or reentry vehicle, they may still be able to pass through the outer shells of those targets and disrupt, damage, or destroy internal components, similar broadly to how a microwave weapon functions.

In addition, since particle beams respond different to different materials, there is the potential that the system might also have the capability to discriminate between real incoming warheads a ballistic missile has released and decoys. Seperate sensors would be necessary to observe the impacts and categorize the results. But if it worked, this would help other ballistic missile defense systems, which generally have short engagement windows to begin with, focus only on actual threats.

The characteristics of these particles would make it hard, if not impossible for an opponent to shield their weapons from the effects or otherwise employ countermeasures, short of destroying the NPB itself, as well. All of this has long made the potential of a particle beam weapon attractive, especially for missile defense.

As part of the Strategic Defense Initiative (SDI) under President Ronald Reagan in the 1980s, the U.S. military experimented with NPBs and hired Martin-Marietta, McDonnell Douglas, TRW, and a team from General Electric and Lockheed to craft potential designs for a space-based system. Between 1984 and 1993, the Strategic Defense Initiative Organization (SDIO) spent approximately $794 million on the concept, according to a 1993 report from the General Accounting Office, now known as the Government Accountability Office (GAO).

McDonnell-Douglas via Aerospace Projects Review

A mockup of McDonnell-Douglas' space-based NPB.

Most notably, in July 1989, Los Alamos National Laboratory (LANL), in cooperation with the SDIO, conducted the Beam Experiments Aboard a Rocket test, or BEAR. This involved placing an actual particle beam system on board a sounding rocket and shooting it out of the Earth’s atmosphere.

As of 2018, this remained the “most energetic particle beam ever flown,” according to LANL presentation. “The experiment successfully demonstrated that a particle beam would operate and propagate as predicted outside the atmosphere and that there are no unexpected side-effects when firing the beam in space.”


A picture of the particle beam-carrying sounding rocket ahead of the BEAR test.

However, the SDIO ultimately pursued a plan to build a massive constellation of space-based kinetic interceptors, known as Brilliant Pebbles, coupled with an equally extensive sensor network in orbit and on Earth. The entire project came to an end in 1993 ahead of the incoming administration of President Bill Clinton, who renamed SDIO the Ballistic Missile Defense Organization – the forerunner of MDA – and refocused its efforts on terrestrial missile defense.

SDIO’s particle beam program proved to be impractical given the technology available at the time. The prospective space-based systems were large and required massive power sources, with nuclear power being the most viable option. Despite hundreds of millions of dollars in funding over nearly a decade between the 1980s and 1990s, the previous NPB effort did not demonstrate a beam powerful enough to produce the desired effects on a target or produce a sufficiently lightweight power source design, according to the 1993 GAO report. Despite the BEAR experiment, there had been no test of an actual complete weapon system by that point, either.

via the National Air and Space Museum

Artwork depicting the NPB system from the BEAR test.

“We’ve come a long way in terms of the technology we use today to where a full, all-up system wouldn’t be the size of three of these conference rooms, right? We now believe we can get it down to a package that we can put on as part of a payload to be placed on orbit,” an unnamed U.S. military official told Defense One in regards to the new particle beam initiative. “Power generation, beam formation, the accelerometer that’s required to get there and what it takes to neutralize that beam, that capability has been matured and there are technologies that we can use today to miniaturize.”

But even if a practical and functional design is possible, there’s no guarantee it would necessarily provide the promised capability, especially against ballistic missiles in their boost phase. Striking missiles in this first stage of their flight is attractive because they are moving relatively slow and are producing a massive heat signature that makes them easier to spot and track. It also means that the missile's contents rain down over or near the launch country in a more localized manner than if destroyed during mid-course or terminal phases of flight.

Unfortunately, they’re also moving through the atmosphere for a significant part of the boost phase. The beam that an NPB shoots out are notably vulnerable to distortion and deflection, since the particles can easily get sent off course by ricocheting off other particles hanging in the air.

There’s a reason why, if you want to build an NPB at all, putting it in the vacuum of space makes the most sense. The amount of power necessary to ensure the beam remains both focused and powerful at appreciable ranges and for enough time to actual damage or destroy a target in the atmosphere could be immense.

An NPB concept from the SDI program using a nuclear reactor at the rear to power the system.

For some context on the potential scale of power generation one might be looking at, in the 1960s and 1970s, the U.S. military had also considered a ground-based particle beam that could defeat ballistic missiles in its latter stages of flight called Seesaw. The Advanced Research Projects Agency determined it would take a system propagating a particle beam across hundreds of miles of tunnels to work properly. 

To create the necessary to power supply, Nicholas Christofilos, a Greek physicist working at the Lawrence Livermore National Laboratory at the time, went so far as to propose using nuclear bombs to effectively create a ludicrously large drain hole that would allow the entire volume of the Great Lakes to flow into a massive hydroelectric generator complex underneath, according to Sharon Weinberger's 2017 book The Imagineers of War: The Untold History of DARPA, the Pentagon Agency that Changed The World. Needless to say, this idea was absurd and the entire program never left the drawing board. 

Technological improvements since then in various fields, such as power generation efficiency and adaptive focusing systems, would reduce these requirements, but they could still be prohibitive depending on other design constraints. This would also be much less of an issue for exoatmospheric engagements.

Beyond these potential technical issues with the beam itself, boost-phase ballistic missile defense systems need to be in an optimal position to engage their target during a very short amount of time after a launch. On average this phase of a missile’s flight is around five minutes at most in total. Sensors would first have to spot and categorize the threat after which American officials would make a decision to engage or not. 

via American Physical Society

A general timeline of the boost phase of ballistic missiles and the time available for defense systems to respond.

Ensuring that there are enough space-based NPBs “parked” in orbit near even a portion of known and possible launch sites could be a costly proposition that would also require significant investments in the U.S. military’s ballistic missile defense sensor architecture, a separate issue you can read about in more detail here and here. The speed of the particles and the range of the weapons in the vacuum of space could help mitigate these issues. It would also be far less of a concern during the mid-course portion of the missile's flight where the entire engagement would occur in space or the very upper reaches of the atmosphere and there would be more time to line up the best shot.

“It’s a very short timeline, first to even know where it [the missile] is coming from…It’s less than a couple minutes before it leaves the atmosphere,” the unnamed defense official that spoke to Defense One admitted. “So, you have to have a weapon that’s on station, that’s not going to be taken out by air batteries and so we have been looking at directed energy applications for that. But you have to scale up power to that megawatt class. You’ve got to reduce the weight. You’ve got to have a power source. It’s a challenge, technically.”

“I can’t say that it is going to be at a space and weight requirement that’s going to actually be feasible, but we’re pushing forward with the prototyping and demo,” this individual continued. “We need to understand as a Department [of Defense], the costs and what it would take to go do that. There’s a lot of folklore…that says it’s either crazy expensive or that it’s free. It needs to be a definitive study.”

Feasibility concerns notwithstanding, there would be political and legal ramifications on top of everything else, too. The 1967 Outer Space Treaty bans the deployment of weapons of mass destruction in orbit. Though the NPB itself would not fit this definition, a nuclear power source would still have the potential to prompt outcry and formal protests. 

A space-based arms race would be another concern and one that is already brewing in the minds of American, Russian, and Chinese officials. The Russians and the Chinese, in particular, are already expanding their arsenals of anti-satellite weapons.


A Russian MiG-31 Foxhound carries an air-launched anti-satellite weapon in a test.

Particle beams by their nature can also be difficult to detect and conclusively trace back to a particular source, making them non-attributable. This is something that Michael Griffin, presently Undersecretary of Defense for Research and Engineering and a major proponent of NPBs, has described in the past as an “advantage." 

But it’s also something that America’s adversaries could look to exploit and weaponize, blaming the U.S. government for all manner of explained phenomena in space.

Russia has a long history of making unsubstantiated allegations against the U.S. government, claiming in recent years that Americans and their allies have staged chemical weapons attacks on civilians in Syria, are actively supporting ISIS terrorists in that country and in Afghanistan, and are running a covert biological weapons program in Georgia. A constellation of particle beam weapons in space capable, at least in principle, of conducting non-attributable attacks, would be an obvious goldmine for Russian propagandists seeking to spread conspiratorial claims, blaming any hole that appears in a spacecraft or malfunctioning satellite on an unprovoked particle beam attack.

It might be hard to challenge these claims. Beyond it's missile defense capabilities, a space-based particle beam does seem like an ideal anti-satellite weapon. It would offer an easy way to quickly knock out satellites, or at least disable them, in a crisis. It would be hard for an opponent to detect such as an attack was occurring in the first place and even more difficult to counter.

But proponents in the U.S. government, especially Undersecretary of Defense Griffin, who worked on the Reagan-era SDI program, are adamant about at least exploring the possibility of a space-based particle beam weapon system. “We should not lose our way as we come out of the slough of despondence in directed energy into an environment that is more welcoming of our contributions. We should not lose our way with some of the other technologies that were pioneered in the ’80s and early-’90s and now stand available for renewed effort,” he declared in 2018.

It remains to be seen whether MDA will determine that the technical and other considerations have changed sufficiently in the last 30 years to make the idea of particle beam weapons in orbit any more practical than it was during the Cold War. But we should get a better idea in the next five years as the Pentagon pushes toward its goal of lofting a prototype particle beam weapon into orbit for the first time.

Contact the author: jtrevithickpr@gmail.com