How could nuclear weapons be used in space?

The Financial Times newspaper has published an article claiming that US warnings over the Russian anti-satellite programme revive Cold War-era concerns about the risks of an orbital conflict. Caliber.Az reprints the article.

Russia is developing a new space-based anti-satellite nuclear weapon, according to intelligence shared by the US government with Congress and European allies. 

Few details are available, so it is hard to know how serious any potential threat might be. Jim Himes, the top Democrat on the House of Representatives intelligence committee, said people “should not panic”.

But the claims have sparked a race to determine what capabilities such a nuclear weapon might have — and what would be the impact on space and on Earth if this type of weapon were to be used.

Why might Russia want to target satellites? 

The US and European countries make extensive use of satellites for military purposes. Their capabilities include monitoring movements of troops and the building of bases, detecting missile launches and organising combat communications. 

Satellites are a significant advantage that the US holds over Russia in conducting conventional warfare, said James Acton, nuclear policy programme co-director at the US-based Carnegie Endowment for International Peace.

Ukraine’s use of the internet provided by Starlink, a private venture of Elon Musk’s SpaceX, against Russian forces shows the importance of satellite-based communications on the battlefield.

In that sense, it is easy to see why Russia might look at ways to damage Western countries’ satellite communications capacity.

The strategic attraction of a nuclear weapon is that it has the potential to destroy many satellites at once. Even the existence of such a device might have a deterrent effect, whether it was ever used or not.

“The US military uses space in a very effective way,” Acton said. “And Russia believes that attacking satellites is a way to level the playing field in that conflict.” 

Russia has, however, a mixed record of developing high-tech weaponry. It has deployed the hypersonic Kinzhal missile in Ukraine, a strategic “super weapon” whose speed was supposed to make it hard to shoot down — but Ukrainian air defences have regularly managed to intercept the devices.

What would be the impact of an attack on satellites? 

The world of satellites is complex, varied — and increasingly crowded. Earth communications and infrastructure increasingly depend on them, from international shipping to home entertainment and smartphone map applications.

Satellites can send signals to — and receive them from — a large number of places on Earth. They bypass the problem of the planet’s curvature, which blocks purely land-based long-distance communications. 

Private sector operators are building constellations of satellites in low Earth orbit. Higher up lie so-called geostationary satellites, located about 36,000km above Earth. The time geostationary satellites take to circle Earth matches the planet’s own 24-hour rotation period, meaning they remain in the same relative position. This enables smooth civil and military communications and means the receiver device never has to change location. 

Russia would have to consider significant practical downsides were it to deploy a nuclear weapon, or threaten explicitly to do so. Any atomic detonation would probably affect other countries’ satellites — including those of the Kremlin’s allies. And fast-moving debris from any explosion could damage or destroy other spacecraft in unpredictable ways.

Have satellites been targeted before? 

Space has increasingly become a realm of superpower competition. Russia, China, India and the US have all destroyed redundant spacecraft in tests of anti-satellite missiles, but the space junk such explosions create could cause havoc in orbit if the debris collides with other satellites.

The most recent strike took place in November 2021, when a Russian missile shot down an old Kosmos 1406 signals intelligence satellite 500km above the Earth. 

The prospect of interference with space-based communications and the development of techniques to do so is increasingly preoccupying military planners. Such methods include using lasers to dazzle satellites. In 2021, Nato pushed through measures to strengthen its response to attacks on satellites.

Militaries are, meanwhile, developing new technologies, such as quantum sensors, that do not rely on global positioning satellites for navigation.

Are there further risks from a nuclear strike in space?

The greatest damage, both to satellites and on Earth, would probably be caused by the electromagnetic pulse that a nuclear explosion would generate. The effects would be similar to those expected from a natural geomagnetic storm following a severe solar flare.

Such an intense burst of electromagnetic radiation would destroy the electronic circuitry in satellites and a vast range of terrestrial computing and communications infrastructure. Power oscillations in electric grids would lead to extensive blackouts.

Radioactive particles generated by an explosion in orbit would spread around the globe at high altitudes. However, humans would not be anywhere near as exposed as they would be from the high levels of radiation produced by an explosion close to the ground. 

The high-altitude nuclear explosions carried out by the US and Soviet Union in 1962, shortly before they agreed to ban atmospheric testing, demonstrated the potential impact. The 1.45 megaton Starfish H-bomb detonated over the Pacific disrupted power and telephone services in Hawaii, while the few satellites then in orbit — including the telecoms pioneer Telstar — were damaged.

What laws prohibit nuclear weapons in space?

The 1962 detonations focused attention on regulating nuclear activities in space. The 1967 Outer Space Treaty forbids the deployment of nuclear weapons there. The leading space nations are parties to the agreement, including Russia, the US and China. 

Under the treaty, which is overseen by the UN, the parties commit not to put into Earth orbit “any objects carrying nuclear weapons”. They undertake not to “install such weapons on celestial bodies, or station such weapons in outer space in any other manner”.

Crucially, the agreement does not cover the firing of nuclear weapons from Earth. “The treaty . . . does not prohibit the launching of ballistic missiles, which could be armed with WMD warheads, through space,” according to the Arms Control Association, a US non-profit group. 

Using nuclear weapons in space would have a big political impact. For Nato countries, it could raise questions about whether Article 5 — the principle that an attack on one member of the alliance represents an attack on all — extends beyond Earth. 

Even countries that have reasonable relations with President Vladimir Putin’s government in Russia would be troubled by the implications for global security of nuclear activity in space. 

This week Putin said his country was “categorically against the deployment of nuclear weapons in space”, but added: “If the west tries to inflict a strategic defeat on us, we will have to think about what strategic stability is.”