Defense officials want to test a neutral particle-beam in orbit in fiscal 2023 as part of a ramped-up effort to explore various types of space-based weaponry. They’ve asked for $304 million in the 2020 budget to develop such beams, more powerful lasers, and other new tech for next-generation missile defense. Such weapons are needed, they say, to counter new missiles from China, Russia, North Korea and Iran. But just figuring out what might work is a difficult technical challenge.

So the Pentagon is undertaking two studies. The first is a $15 million exploration of whether satellites outfitted with lasers might be able to disable enemy missiles coming off the launch pad. Defense officials have said previously that these lasers would need to be in the megawatt class. They expect to finish the study within six months.

They’re also pouring money into a study of space-based neutral particle beams, a different form of directed energy that disrupts missiles with streams of subatomic particles traveling close to light speed — as opposed to lasers, whose photons travel at light speed.

On Wednesday, officials speaking to reporters at the Pentagon voiced guarded confidence that they would result in something that would in fact be deployable.

It’s not the first time that the Department has looked at such weapons. In 1989, the U.S. launched a neutral particle beam into space, as part of an experiment called BEAR, for Beam Accelerator Aboard a Rocket.

The experiment report described it as modestly successful: “The BEAR flight has demonstrated that accelerator technology can be adapted to a space environment. This first operation of an [neutral particle beam] accelerator in space uncovered no unexpected physics.”

But there’s a big difference between a successful experiment and an affordably deployable weapon. As part of the earlier effort, several companies produced prototype designs. The weapons they sketched were enormous. One was 72 feet long.

On Wednesday, Defense officials said that advances in technology have brought down the potential size and cost of space-based particle beams.

“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,” said a senior defense official. “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.”

Officials, however, stress that the explorative studies do not necessarily mean that the Department will actually deploy a weapon. “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,” said an official. The exploration, according to the official, “means we need to understand as a Department, 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.”

The push to develop space-based weapons also reflects growing concern about advances in missile technologies from adversarial and so-called “competing” nations like China, Russia, Iran and North Korea.

“The addition of the neutral particle Beam effort will design, develop, and conduct a feasibility demonstration for a space-based Directed Energy Intercept layer. This future system will offer new kill options for the [Ballistic Missile Defense System] and adds another layer of protection for the homeland,” says an MDA document put out on Tuesday.

Those new options are essential, say defense officials, to hit missiles during their boost phase, as they leave the launch pad and head straight up.

“That’s a really hard battle space to go after, right?” said the senior official. “It’s a very short timeline, first to even know where it [meaning the missile] is coming from…It’s less than a couple minutes before it leaves the atmosphere. 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.”

It’s also a controversial idea and not popular among arms control proponents. “The deployment of interceptors in space would be a disaster for strategic stability. To ensure the credibility of their nuclear deterrents, Russia and China would likely respond by building additional and new types of long-range ballistic missiles as well as missiles that fly on non-ballistic trajectories. Russia and China could also take steps to improve their ability to destroy such U.S. interceptors, thereby greatly increasing the threat to U.S. assets in space,” said Kingston Reif, who directs disarmament and threat reduction policy at the Arms Control Association.

The U.S. is a signatory to the 1967 Outer Space Treaty, which prohibits placing nuclear weapons in space. Another Defense official made clear that the treaty does not provide an obstacle to the deployment of either lasers or neutral particle beams in orbit. “The 1967 Outer Space Treaty says that weapons of mass destruction can not be placed into outer space and then it limits even further specifically military activities on celestial bodies, I think the moon or otherwise. But the treaty does not expressly prohibit activities that are not weapons of mass destruction on outer space.”

If the Defense Department does deploy weapons in space, the United States would be the first country to do so officially. But defense officials frequently contend that they probably would not be the first to do so in actuality. A February report from the Defense Intelligence Agency suggests that both China and Russia are developing space-based weapons and that they could be in orbit next year.