One very bad day

The United States believes Russia is developing a nuclear weapon that could be put into orbit and detonated to knock out satellites. If that happened, what would you and I experience, and what would happen at a granular level to the satellites that are so central to modern life? Mike Gruss set out to find out.

One thing that can be said with certainty is this: If a nuclear bomb were detonated in orbit, there would be no mushroom cloud since there would be no atmosphere for the warm air and debris to rise through.

Another is that things would be bad.

“So bad,” one expert says. “Catastrophic,” says another. “Warranted hyperbole,” says a third.

In 1962, the final time the United States detonated a nuclear device in space, a mere two dozen satellites orbited Earth. Now there are some 10,000 active ones, and growing. Lots of them are military in nature, some are hybrids and others are purely civilian. Taken together, they show us where we are and where we’re going, make our debit cards work, connect us across continents, keep watch of the weather and our changing environment, provide intelligence for winning wars and avoiding them, and more. There are now, literally, too many applications to name.

And so in February, minds quickly went to a nuclear device when a U.S. lawmaker revealed the existence of intelligence about a “serious national security threat” that he did not specify. At first, the White House called the purported weapon an “anti-satellite capability” that was in development by Russia but declined to say whether it was a nuclear weapon. A clue came in April, when Japan and the U.S. introduced a resolution at the United Nations Security Council that would have reaffirmed the 57-year-old international ban against stationing nuclear weapons in space. Russia vetoed the resolution, even though President Vladimir Putin had earlier said that the country is “categorically opposed to the deployment of nuclear weapons in space.” Then, in what remains the clearest statement about the intelligence, National Security Adviser Jake Sullivan said the U.S. believes Russia is developing “a new satellite carrying a nuclear device.”

If the U.S. intelligence is accurate, detonating such a weapon would harm more than the interests of the U.S.

“This capability could pose a threat to all satellites operated by countries and companies around the globe, as well as to the vital communications, scientific, meteorological, agricultural, commercial, and national security services we all depend upon,” John Plumb, then the Defense Department’s assistant secretary for space policy, wrote in testimony submitted during a May congressional hearing.

What exactly would we experience? First, here’s a caveat: Not everything I’m about to tell you, gleaned from speaking to eight experts in the space and atomic fields, reflects absolute certainty. “Aspects of physics governing induced nuclear-weapon environments are imprecisely known,” chimed the U.S. Defense Threat Reduction Agency in “Collateral Damage to Satellites from an EMP Attack,” a 2010 paper that discussed nuclear war in space. EMP stands for electromagnetic pulse, a wave of energy that’s caused by a surge of gamma radiation colliding with molecules in the atmosphere, according to, a website funded by the U.S. National Science Foundation.

The gap in predicting the effects of such a blast hasn’t entirely closed since that paper was written. So here goes.

For some of us, the bad begins with beauty. If we’re driving or walking in the dark of a cloudless night and the blast is out of sight beyond the horizon, an aurora erupts not unlike the northern lights seen unusually far south around the world in May. That show was caused by streams of electrons and protons spewed toward Earth in one of the sun’s periodic series of coronal mass ejections. The particles collided with the gases in the upper atmosphere, triggering billions of “tiny flashes” in sequence, giving the aurora its shifting appearance, as the Canadian Space Agency explains on its website. The mechanism would be similar after a nuclear blast: Charged subatomic particles from the detonation would slam into oxygen and nitrogen high in the atmosphere, causing the release of electromagnetic energy in the visible spectrum.

Others of us would experience a more frightening show. We sense a flash and look up to see an object as bright as the sun. In 1962, a nuclear detonation created a “spectacular pyrotechnic aftermath” that lasted 7 minutes, according to the Honolulu Advertiser: “It was like turning on all the lights all over the Hawaiian Islands.”

Next comes the figurative fallout that disrupts nearly all our lives for weeks or months — and maybe many years.

Like a log after a campfire

A nuclear detonation splits atoms into electrons and protons, and when that happens, X-ray radiation races off in all directions. This radiation would pass through the satellites nearest the weapon, those tens to hundreds of kilometers away.

Gennady Miloshevsky studies what would happen to materials following a nuclear detonation. He is an assistant professor of mechanical and nuclear engineering at Virginia Commonwealth University, and a member of a research consortium with the Pentagon’s Defense Threat Reduction Agency and Johns Hopkins University. The damage in any hypothetical scenario, he and others say, depends on two factors: how close the satellites are to the explosion and the amount of energy released, known as the yield of the weapon. The closer the distance and the greater the yield, the worse it would be.

One of the first areas to find trouble would be the solar arrays. These expanses of cells are typically made of compounds containing the soft metal gallium. The arrays are extended as far as practical from the spacecraft to maximize sun exposure, and they must be large to convert as much sunlight as possible into electricity. For example, NASA’s Europa Clipper spacecraft scheduled to be launched in October will be 30 meters long once fully deployed, but roughly 28 of those meters will come from its solar arrays.

Clipper will head off to the safety of the Jupiter system, but numerous satellites with large panels also orbit Earth. They are “potentially vulnerable to prompt radiation from a high altitude nuclear explosion,” the Defense Threat Reduction Agency said in a 2016 document, “Fundamental Research to Counter Weapons of Mass Destruction.”

As we’re making sense of what’s happening in the sky, X-rays have already wreaked havoc on solar panels. They’ve pierced their antireflexive coating, the cover glass, the adhesive and then the semiconductors, converting most of the components to a dense plasma and leaving behind a dry foam, judging from images from NASA scientists. Then, that material flakes off, leaving the arrays damaged or possibly ruined and rendering the satellite dead.

Whether the satellite is in low-Earth orbit, medium-Earth orbit or geosynchronous orbit doesn’t matter, Miloshevsky says. If the satellite is in sight of the detonation, it would be damaged.

And from there, matters get worse.

The epiphany

For at least 20 years, U.S. military leaders have talked about the importance of satellites by repeating the findings of a hypothetical “day without space.” If satellites — military, civilian or commercial — didn’t exist or were deemed unusable, what would it mean on Earth? The Pentagon began holding training to bolster awareness and funding for programs.

Then-Army Lt. Gen. Joe Cosumano dove into that scenario in the Army Space Journal in 2002: “First, most pagers, phones, personal data devices, radios and televisions would become silent because in one way or another they rely on satellites for the transmission of the information that flows to and from them,” he wrote. “All land, sea and air vehicles leveraging the Global Positioning System for precise location and navigation would have to come up with another means to determine their exact location and navigate from where they are to where they want to go. Weather forecasters would not have access to satellite photos of current weather conditions around the world and in their local areas. Mapmakers wouldn’t have current satellite images from which to update their products. And you might actually have to pay the cashier for your gas, instead of paying at the pump with your credit card.”

There were practical implications for the military as well for imagining what a world without space operations would mean. In 2008, the chief scientist at Air Combat Command conducted a nine-month study on how the Air Force could “fight through” the loss of satellites and ground stations, as well as how to rapidly rebuild what could be lost. By 2010, the Pentagon held training exercises explicitly to learn how to operate using air, ground and sea systems in the event that satellites were not available.

Since then, the world’s reliance on space has only become greater.

U.S. generals like Cosumano aren’t the only ones who have sounded the alarm over the years. World leaders have long worried about nuclear weapons in space. Members of the United Nations first started talking about proposals to limit space to peaceful and scientific purposes in the 1950s.

Amid the tension of the Cold War in the 1950s and 1960s, the U.S. and Soviet Union were demonstrating their technical prowess without shame. “The battle between East and West is seen by the USSR as a conflict in the field of science and technology,” said the United Kingdom’s Sir Bernard Lovell, director of the Radio Astronomy Laboratories at Jodrell Bank, in May 1962, according to a 1976 historical account by Los Alamos Scientific Laboratory. “Some of the American and probably some of the Russian space activities are not being guided by the purest of scientific motives,” he added.

The Soviet Union started its testing of nuclear “events” or “experiences” in space, referred to as Project K, with a first launch in October 1961 and three tests over 10 days in late October and November 1962.

The U.S. conducted at least a dozen such experiments from 1958 to 1962. Perhaps the best known was July 1962’s Starfish Prime. The U.S. made no effort to hide preparations for the experiment. It was an event of “worldwide scientific interest. Yield, altitude, and time of event were announced prior to the event,” according to the Los Alamos account.

The Air Force, at the behest of the Atomic Energy Commission, put a nuclear “device” on a missile and launched the warhead from Johnston Atoll in the Pacific Ocean. It detonated at an altitude of 400 kilometers, roughly the same altitude at which the International Space Station orbits today.

The effects of the electromagnetic pulse and resulting geomagnetic storm were felt in Hawaii 1,400 kilometers away. Three hundred street lights in Oahu were knocked out, according to the Honolulu Star-Bulletin. Burglar alarms were reportedly set off and telephone lines damaged.

The effects were also felt in space: Within a month, at least six satellites failed, which was a significant number given that just 24 satellites were on orbit at this time. The world was experiencing an epiphany about the dangers of nuclear detonation in space.

Fifteen months after Starfish Prime, the U.N. passed a resolution calling on nations to “refrain from placing in orbit around the earth any objects carrying nuclear weapons or any other kinds of weapons of mass destruction.” That passage later became part of the 1967 Outer Space Treaty, signed by the U.S., Soviet Union and 87 other countries.

It’s that treaty that diplomats and U.S. leaders point to today. “A nuclear detonation in space would present a catastrophic impact to space activity,” says Eric Buhr, senior project leader in the Aerospace Corp.’s electrical systems assurance department.

Risk of redout

Assuming the solar arrays on a satellite can still turn sunlight to electricity, another concern is the satellite’s instruments.

Space experts have worried for years about dazzling — when a bright light or laser causes an imaging instrument to temporarily lose its ability to capture an image — or blinding, when such a flash causes permanent damage by saturating the instrument’s detectors. A nuclear detonation would do something similar, sending high-energy photons flooding into the instruments and causing them to stop working, at least temporarily. The flash can burn out a sensor or flood an instrument’s sensors, such as a camera, referred to as a blackout or redout.

The effect threatens not just imaging satellites used for map-making, agricultural applications and intelligence gathering such as examining weapon sites but also for the star tracker cameras carried by many satellites. These look at star patterns and constellations so that the satellite can maintain its proper attitude, or orientation.

As for the EMP, just like in Starfish Prime, gamma rays from the explosion cause air molecules to ionize, creating a pulse of energy that produces a geomagnetic storm that boosts the atmosphere’s conductivity. Large spikes in voltage reach Earth’s surface while exposing satellites to immediate gamma rays and X-ray radiation.

If a power grid is grounded to the earth, the current goes there, says Jeffrey Love, a geophysicist who has studied some effects of EMP.

“You end up with these uncontrolled currents in the power grid system, which is designed for tightly controlled currents, and that can cause the power grid to malfunction and possibly even damage it,” he says.

That is what happened in Hawaii with Starfish Prime. The electricity generated by the detonation needed somewhere to go, and it found a home by spreading through connected street lights that subsequently shorted out. If the detonation took place over the continental U.S. — and not thousands of kilometers away like with Starfish Prime — a power outage could extend to wide swaths of the country.

“That’s an effective way to spread mischief,” Love says.

The fallout continues

Some spacecraft will be far enough from the blast that they won’t be knocked offline, but their owners should not breathe a sigh of relief. As Aerospace Corp.’s Buhr puts it, “Surviving spacecraft orbiting in the same orbit regime as the nuclear detonation likely would experience premature degradation and/or failures.”

Here’s why: The initial blast creates an artificial radiation belt, almost like a bubble, that circles Earth. That belt includes electrons and protons that do not fall into the atmosphere but are instead trapped in space by Earth’s magnetic field.

It might be days or weeks or months, but as satellites fly through that belt, many — possibly hundreds or even thousands — would likely fail.

“Energetic electrons and protons penetrate spacecraft materials creating ionization,” according to a 2014 article from Dispatch, the Defense Threat Reduction Information Analysis Center newsletter. “Accumulated exposure … can result in damage and degraded operation of electronic components, solar cells, and mirror surfaces.”

Think back to 1962. Today, there are 400 times more active satellites on orbit, many of which are smaller and some just the size of a shoebox. While many of these designs are meant to last only a few years, either from a business perspective or for academic reasons, they almost certainly are not hardened to withstand a sudden or sustained increase in radiation. That’s a luxury that many satellite owners simply cannot afford or need, says Michael Swartwout, an associate professor of aerospace and mechanical engineering at St. Louis University. Instead, many would start to degrade in weeks or months.

In addition, the business model of some satellite companies — think SpaceX’s Starlink or Planet’s Dove imaging satellites — depend on the regular replenishment of satellites. In the event of a nuclear detonation, their assigned orbital belts in LEO may not be safe for new satellites for years.

Conversely, some U.S. military and intelligence satellites have been hardened and designed to keep operating through intense radiation. Six of the Space Force’s Advanced Extremely High Frequency communication satellites, for example, are meant to provide protected communications even in the event of a nuclear attack that takes place on Earth, but not on orbit. Experts say whether they would survive a detonation on orbit would again be determined by the size of the weapon and the range of the blast.

The August 2010 paper written by researchers for the Defense Threat Reduction Agency said satellites in medium-Earth orbit, where GPS satellites fly, or geosynchronous orbit, where some of the military’s crown jewels, such as AEHF satellites operate, “are already designed to operate in the relatively severe natural radiation environments at such altitudes.”

But the paper acknowledged any kind of detonation in space could still take years off a GPS satellite’s expected life.

Decades of trouble

For the satellites that survive the challenge to instruments, the radiation and the electromagnetic pulse, there’s another long-term problem: debris.

In 2007, China launched a missile and destroyed one of its nonoperational weather satellites as part of a show of strength. The single event created some 3,000 pieces of long-lasting debris that researchers can track, with about 900 of those projected to still be in orbit in 2035. In the meantime, satellite operators have to navigate around the debris to avoid damaging collisions.

Experts says it’s difficult to predict how many satellites a nuclear detonation would immediately destroy. Maybe 10? Maybe hundreds? But John Crassidis, a professor of innovation in the department of mechanical and aerospace engineering at the University of Buffalo who studies space debris, says the pieces from those satellites would create a cascading effect: Debris damages a satellite, making it uncontrollable and leading it into the path of more debris, which could then create more collisions and eventually chaos.

“It might cause Kessler Syndrome to become a reality right away, where the chance of colliding with that debris is so big that it’s not worth putting satellites in low-Earth orbit anymore,” Crassidis says.

The situation could create 50 years worth of debris in two years, he suggests.

“If low-Earth orbit becomes useless, we’re in a lot of trouble,” he says.

Even if a business thought it could still operate satellites safely, the companies that insure satellites must be convinced.

“Nobody’s going to insure them anymore,” Crassidis predicts. In addition, any astronauts traveling to the moon and Mars would have to navigate through this debris field.

Much of what would happen is unknown. Still, enough is known to frighten.

“It affects everyone, right? Every single country,” the U.S. State Department’s Mallory Stewart said in May during an event hosted by the Center for Strategic and International Studies in Washington, D.C. “It’s indiscriminate in its potential effect” because “it would affect everyone, including China and India, and Russia’s own satellites. So, it’s extraordinarily destabilizing.”

So even though we would not see a mushroom cloud, the fallout would be visible just the same.

Related Topics

DefenseSpace safety

About Mike Gruss

Mike freelances from northern Virginia. Previously, he was editor-in-chief of Sightline Media Group, where he led publications including Defense News and Military Times, and was the military reporter at SpaceNews.

Side-by-side images: left, a bright white ring against a dark background; right, a glowing, orange-red nebulous shape with a blue tinge at the bottom.
The 1962 Starfish Prime test was the largest U.S. nuclear detonation in orbit, occurring at an altitude of 400 kilometers and releasing 1.4 megatons of energy — almost 100 times that of the atomic bombs that the U.S. dropped over Hiroshima and Nagasaki, Japan, in 1945. The blast was photographed from a host of perspectives. Credit: Defense Threat Reduction Agency
A night sky with streaks from star trails and satellites over a landscape of brush and distant mountains, under a partially cloudy sky.
A nuclear detonation in low-Earth orbit would leave protons and electrons lingering at the altitudes occupied by spacecraft such as this train of SpaceX Starlink satellites, whose reflected sunlight was captured in this timelapse photo of the New Mexico sky. Credit: National Optical-Infrared Astronomy Research Laboratory/M. Lewinsky
Technicians in white lab coats and hair coverings work on assembling large solar panels in a cleanroom-like environment.
One of the satellite components most vulnerable to a nuclear detonation would be the solar arrays that convert sunlight into electricity. The arrays could be degraded by the radiation such a detonation would create, or they could be pierced by the debris of other spacecraft destroyed by the detonation. Credit: NASA

One very bad day