explainers

A risky venture What a nuclear weapon in space is capable of — and why Russia might want one

Source: Meduza

This past February, after U.S. House Intelligence Chairman Mike Turner issued a vague warning about a “serious national security threat,” U.S. media, citing intelligence sources, reported that he was referring to alleged Russian plans to put satellites equipped with nuclear weapons into orbit. According to The Wall Street Journal, Russia already has a satellite in orbit that’s being used to test components and systems for this new type of weapon. Half a century ago, the U.S. and the Soviet Union signed international treaties banning nuclear weapons and testing in space precisely because they both realized the destruction it could cause. Meduza explains the effect nuclear weapons actually have when detonated in orbit and why Russia might be interested in having space nukes at its disposal.

De jure, Russia is prohibited from deploying nuclear weapons in space. Article IV of the Outer Space Treaty stipulates that the signatory states agree “not to place in orbit around the earth any objects carrying nuclear weapons or any other kinds of weapons of mass destruction, install such weapons on celestial bodies, or station such weapons in outer space in any other manner.” Any attempt to send a nuclear device into orbit would be considered a violation of this international treaty.

Violating this would also contravene Russian law: international treaties ratified by the Russian Federation become part of Russian legislation and must be observed just as strictly as, say, the Labor Code. Russia (then part of the Soviet Union) ratified the Outer Space Treaty in 1967 and remains a party to it to this day.

Before 1967, however, both of the world’s largest nuclear powers — the U.S. and the U.S.S.R. — experimented with detonating nuclear charges at high altitudes, including in near space.

The first space nukes

When nuclear weapons were first developed in the mid-20th century, no one knew exactly what they were capable of. Nuclear powers conducted dozens of test explosions to determine how blast waves could affect bridges, buildings, and armored vehicles. It also wasn’t clear what effects the gamma radiation from a nuclear explosion could have on people in open areas, trenches, or varied terrain. To find answers to these questions, bombs were detonated underwater, on the Earth’s surface, and at various altitudes, including in space.

However, the first explosions in space were very different from other nuclear tests. Their purpose wasn’t to test the design of nuclear devices or how well military infrastructure could withstand such an explosion (at that time, there wasn’t any military infrastructure in space). They were largely scientific experiments aimed at testing certain hypotheses about near-Earth space and the effects of explosions on its properties.

The energy of a nuclear explosion in the initial stage is primarily released in the form of X-rays and gamma radiation, but a significant part of this energy is also released as nuclear decay products — neutrons, nuclear fragments, electrons, and protons. In an explosion within Earth’s atmosphere, these particles are quickly absorbed, but in space, nothing impedes their travel.

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In 1958, American physicist Nicholas Christofilos hypothesized that a nuclear explosion several hundred miles above the Earth would act as a powerful source of high-energy particles and create a shell of high-energy electrons in the upper layers of the atmosphere, oriented along the Earth’s magnetic field (similar to Earth’s two naturally occurring Van Allen radiation belts).

Christofilos’ assumptions were of great interest to the U.S. military because of the impact this kind of artificial radiation belt could have on defense systems. His hypothesis suggested that a nuclear warhead detonated high above the Earth could seriously impair or even interrupt radio signal transmission and reception, as well as radar operations. An artificial radiation belt could also damage the electronic systems of a ballistic missile flying through it.

In order to test this, the U.S. conducted the first series of experiments with nuclear explosions in orbit in history: Operation Argus. In late August and early September of 1958, the U.S. military detonated three low-yield warheads over the South Atlantic Ocean. Observations showed that warheads with a yield of one to two kilotons, detonated at an altitude of about 90-125 miles, did indeed create artificial radiation belts between Earth’s two natural ones. Artificial auroras appeared in the area of the explosion over the South Atlantic and at the mirror point in the north, near the Azores. Most importantly for the military, there were malfunctions in radar operations.

Four years later, the U.S. conducted a new nuclear test, Starfish Prime, with a significantly more powerful charge and at a higher altitude — and with a wider range of objectives. The U.S. military wanted to know whether a nuclear detonation in space could damage ballistic missile warheads flying at that altitude and how it might affect military communication and control systems. They also wanted to determine whether a nuclear explosion in space could conceal enemy missiles flying in that area and whether artificial radiation belts could be used as weapons.

On July 9, 1962, after two failed attempts, the U.S. military launched a 1.45-megaton nuclear charge from Johnston Atoll in the Pacific Ocean and detonated it at an altitude of 250 miles, about the height where the International Space Station (ISS) currently orbits. The explosion generated a powerful electromagnetic pulse significantly stronger than the scientists expected — so much so that most of the measurement equipment didn’t work properly, making it impossible to get accurate readings. About 800 miles away in Hawaii, around 300 streetlights went out due to blown fuses, security alarm systems activated on their own, and residents reported garage doors opening and closing by themselves. Increased radiation from the blast lingered for years, damaging satellites that flew through the area and leading to their demise.

From 1961 to 1962, the Soviet Union conducted its own series of nuclear tests in space, known as the K Project, over a test site in Kazakhstan. The detonations significantly damaged local infrastructure, causing underground power cables to fail, disrupting telephone service, and triggering numerous short circuits and fires.

Since there’s no medium in orbit for a shock wave to propagate through, the primary destructive effects of a nuclear detonation in space are radiation and electromagnetic pulse. Gamma radiation from the explosion interacts with atoms in the upper atmosphere, ejecting electrons from them. These electrons, captured by Earth’s magnetic field, create variable electric currents and powerful electromagnetic fields, which, in turn, can induce strong currents in conductors and disable electronic equipment. The electrons and ions produced at the moment of the explosion behave in a similar manner, contributing to the overall effect.

The impact of charged particles and ionizing radiation on satellite networks would be incredibly destructive. The flow of high-energy particles from a nuclear explosion in space would take out electrical control systems, causing transistor breakdowns and short circuits and rendering the spacecraft useless space debris.

In 1963, just one year after Starfish Prime and the K Project, the U.S. and the Soviet Union signed the Limited Test Ban Treaty, which includes a prohibition on nuclear testing in the atmosphere or outer space. This was partly because, even at the dawn of the space age, it was clear that a nuclear explosion could destroy one’s own satellites just as easily as the enemy’s.

Defining a weapon

While there are treaties limiting the militarization of space and the placement of certain types of weapons there, this doesn’t mean there isn’t military infrastructure in space. In fact, many U.S. and Soviet space projects began as military initiatives (or at least space agencies used military interest in their projects to secure funding). Optical and radio reconnaissance satellites, as well as military communication and navigation satellites, are commonplace. In recent years, however, U.S. officials and intelligence have accused Russia of starting an arms race in space, claiming that Moscow is developing and testing something in orbit that doesn’t fit within the framework of the Outer Space Treaty. Their statements are vague but mainly refer to two things: anti-satellite weapons and inspector satellites.

Even during the Cold War, both the U.S.S.R. and the U.S. were developing satellites to destroy missiles and missiles to destroy satellites, along with other missile defense systems. But more recent concerns about anti-satellite weapons began in 2007 when the Chinese military shot down an old weather satellite. It disintegrated, leaving over 3,000 documented fragments in orbit. This one test increased the amount of space debris by 10 percent, posing risks to other spacecraft, as well as the ISS.

The following year, the U.S. conducted its own anti-satellite test for the first time since 1986, shooting down the USA-193 satellite. The official explanation was that the satellite's rapidly decaying orbit and remaining toxic hydrazine fuel necessitated its destruction. However, Moscow claimed this was merely a pretext for testing missile defense systems. This time, there was significantly less debris: the satellite was in low orbit when it was shot down, and within a year and a half, it had all burned up in the atmosphere.

Since 2014, the U.S. has been claiming that Russia is developing and testing its own anti-satellite missiles. These concerns were confirmed in November 2021 when the Russian military tested the Nudol anti-satellite missile, shooting down the Cosmos-1408 satellite and adding about 1,500 new pieces of debris to orbit.

Additionally, U.S. military officials have repeatedly asserted that Russia is developing and deploying another type of anti-satellite weapon — orbital devices capable of approaching other satellites and potentially disabling or inspecting them. This seems to be true: in 2020, amateur astronomers who monitor satellites in orbit discovered that the Russian Cosmos-2542 was actively hunting a U.S. reconnaissance satellite.

A fundamentally new threat

In February 2024, after U.S. intelligence about a new Russian weapon described as “anti-satellite technology” came to light, The New York Times reported that the intelligence concerned Russian plans to launch a nuclear-armed device into space. The weapon, if detonated, is allegedly capable of disabling thousands of satellites — potentially disrupting communications, navigation, and Earth observation systems in numerous countries. Russia denies the accusations. In May, The Wall Street Journal, citing its own sources, reported that Russia already has a satellite in orbit testing components for a future orbital anti-satellite nuclear bomb — Cosmos-2553.

Russia launched Cosmos-2553 from the Plesetsk Cosmodrome on February 5, 2022 — just weeks before beginning its full-scale invasion of Ukraine. As with all other Russian military vehicles, officials didn’t disclose its purpose. However, they did say the satellite is “equipped with newly developed onboard instruments and systems for their testing under conditions of exposure to radiation and heavy charged particles.” Virtually all the verifiable information about the project is that the satellite is being kept in a 2,000-kilometer (1,243-mile) orbit with an inclination of 67.1 degrees.

Bart Hendrickx, a journalist and Russian language teacher who’s studied the Russian space program for many years, asserts that this spacecraft is actually a satellite called Neitron, developed by NPO Mashinostroyeniya on the basis of its Kondor series. (Kondor satellites are used for radar imaging of Earth and likely also double as radar or optical reconnaissance satellites.) Independent observers agree with his assessment.

Hendrickx supports his claim by noting that the launch vehicles and expected orbital inclinations of both spacecraft are identical. However, his primary argument is based on Cosmos-2553’s orbit, which is too high for an optical reconnaissance satellite but suitable for radar imaging. He points out that the satellite passes over the same point on Earth’s surface every four days, making it “ideal for interferometric synthetic aperture radar (InSAR) imaging” — a method that combines multiple images of the same location to create a 3D map of the Earth’s surface.

It’s unclear how exactly this is connected to nuclear weapons. Historically, intelligence data is often inaccurate, and sources leaking information to the press may have their own political agendas.

The main question seems to be why Russia would need a hypothetical nuclear device in orbit in the first place. The NYT suggests that it could be a way for Vladimir Putin to hold the U.S. satellite network at gunpoint, a tool he could use to “destroy economies without targeting humans on earth” should he not get what he wants. 

There are also possible military arguments in favor of placing nuclear bombs in orbit. As military historian Igor Kurtukov notes, the situation in near-Earth space has changed in recent decades: instead of single expensive satellites, there are now swarms of cheap, easily replaceable ones, launched by the dozens. It no longer makes sense to shoot down satellites one by one with anti-satellite missiles when they’re working together in a network, transmitting data to each other. To combat them, you need a weapon that can disable many satellites at once: either a bomb filled with space debris or something more reliable — like an electromagnetic pulse and charged particles from a nuclear explosion.

But launching a nuclear bomb into orbit is an extremely risky venture: the satellite carrying it could malfunction, collide with a piece of space debris, or fall out of orbit and crash somewhere unpredictable. This already happened in 1978 when the Soviet satellite Cosmos-954, which had an onboard nuclear reactor, crashed on Canadian territory, causing radioactive contamination. And even if satellites did need to be destroyed with nuclear weapons, tests like Starfish Prime show this can be done with a standard ballistic missile carrying a nuclear warhead.

“Placing nuclear weapons in space makes no sense,” Pavel Podvig, a senior researcher at the U.N. Institute for Disarmament Research, told Meduza. “If you try to destroy a [satellite] network, then firstly, there’s no guarantee at all of success. And secondly, you’d destroy many other satellites [in the process].”