U.S. space weapons probably aren’t what you think
Scientific American · LC · trust 39/100
Elusive, satellite-stalking spacecraft could unleash space war—or help keep orbital peace
When the U.S. announced that it has placed weapons in space on September 14, it came as a surprise to absolutely nobody familiar with the subject.
“My initial impression was that it was about time to announce it since it was the worst-kept secret in the world,” says Doug Loverro , who was deputy assistant secretary of defense for space policy during the second Obama administration.
Military use of space isn’t new. Armed forces of the U.S. and other spacefaring countries have relied on satellites for surveillance and navigation for more than half a century—in the 1960s the U.S. and the Soviet Union even blew up nuclear bombs in space. The GPS (Global Positioning System), weather and communications satellites upon which so much of our modern lives on Earth now depend all have militaristic roots. And as this dependency has grown, so, too, have countries’ concerns about defending their assets in space. Gradually, Earth orbit has become not just a place for a god’s-eye overview of our planet but also a hotly contested war-fighting domain.
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This admission from the U.S., says Jonathan McDowell , an astrophysicist who tracks rocket launches and in-space activity, is just the next step in that process.
“It’s not out of nowhere,” he says. “The U.S. remains the country that is the most dependent on space assets for its operations, and to that extent, it remains the country that has the most to lose from space conflict.”
Loverro believes the announcement wasn’t much more than an acknowledgment of what people could already see for themselves by looking up. While their actual missions may remain secret, most classified military satellites can be easily tracked and cataloged from the ground. “If we don’t tell them what it is, they’re going to hypothesize what it is—so let’s just be clear,” he says.
Even so, no other nation has ever publicly acknowledged its possession of space weapons. The U.S.’s decision to do so now presumably signals to potential adversaries with thinly veiled space weapons of their own—namely China and Russia—that a new era of accountability for orbital saber-rattling is at hand. But two burning questions remain: What are these space weapons, exactly? And what might they mean for our future down here?
The answers probably aren’t what you’d think.
Space weapons can come in four broad categories, most experts say: nuclear bombs , directed-energy weapons , kinetic antisatellite weapons and platforms for disrupting or disabling satellites’ activity without actually destroying them. For the latter category, the most effective results would probably come from a platform getting close to an adversarial spacecraft via what’s known as rendezvous and proximity operations (RPOs).
Nuclear weapons in space are banned by the 1967 United Nations Outer Space Treaty , and the consensus is that they would be Very Bad for everyone. Blowing up a nuclear bomb in space would first destroy or disable any nearby satellites, and then the damage would spread as electronics-frying energetic particles from the explosion contaminated huge swaths of orbit. If that wasn’t bad enough, the dead satellites would start crashing into things, creating cascades of high-speed debris that could destroy most remaining satellites in a catastrophic domino effect called Kessler syndrome .
Back on Earth, we’d likely see beautiful flashes of color in the sky—followed by severe economic shocks and military conflict erupting around the globe as crucial space-based services went dark. Though the U.S. has accused Russia of seeking to loft nuclear weapons into orbit, detonating a warhead in space is highly unlikely right now, says Jeffrey Lewis , an expert on nuclear security at Stanford University.
“The only reason you would do that is if you are looking at the entire space landscape and you’re thinking to yourself, ‘I’d like to be able to hit delete,’” Lewis says.
Kinetic antisatellite weapons are things like missiles or other spacecraft that smash into and shatter satellites. The linebackers of orbit, these weapons may be effective but aren’t necessarily the most strategic. The resulting shrapnel, while less than that of a nuclear explosion, would still pose grave hazards, going against the U.S. military’s long-standing (but informal) policy of avoiding debris-generating activity in space. So that’s out.
Directed-energy weapons—think big lasers—could take down satellites, too. In some respects, these would be a military planner’s dream: they could be built and operated on the ground or carried into space, and their precision-targeted beams could move at the speed of light to intercept and disable spacecraft while creating minimal debris. Loverro, who oversaw U.S. space war fighting from 2013 to 2017, says this is probably the tool he’d reach for if he were choosing a space weapon.
But laser weapons “probably aren’t technically mature enough” yet, McDowell says, and their use would be a very aggressive show of force at this point.
That leaves the wide-ranging category of interfering with satellites through RPOs and other subtle means. One of the most obvious scenarios, McDowell says, entails a space-based platform using an RPO to approach a target and disrupt its communications or sensing; that’s why he thinks that the U.S. weapons announced earlier this month are probably satellites that will “go up next to…
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