Electromagnetic pulse attacks are one of those things that keep some military officials wide awake at night -- and put others soundly asleep. It all depends on who you’re talking about.
For the former, including a number of doomsayers, missile-defense boosters, and prominent politicos, the risk is that a rogue state could emit a blast of electromagnetic energy by way of a nuclear explosion in the upper atmosphere, frying electronic systems from California to Cape Cod.
For skeptics -- and many scientists -- it’s all an overblown theory containing loads of technical and practical problems. More realistically, it'd be lights out when we’re eventually hit by a rare and exceedingly powerful solar storm.
But concerns about weaponized EMP persist. The Defense Threat Reduction Agency, a Pentagon body focused on countering threats from nuclear weapons, has put out the call for new studies into the phenomenon, according to a notice from the agency posted in December. Specifically, DTRA wants to research "high-altitude weapons electromagnetic pulse effects modeling" for satellites.
The ultimate goal is to come up with a uniform military standard for EMP effects on satellites, which could later be used to harden them against an attack. The term "effects modeling" in the notice refers to laboratory simulations. DTRA has also stressed it's not trying to predict the likelihood of an e-bomb attack, just the expected results of one.
We have some experience with this -- albeit with several gaps.
For one, we do know that satellites in low-earth orbit would be in grave danger of getting zapped by EMP. Satellites at these orbits include ones used for high-resolution imagery, monitoring the weatherb and handling telecommunications. They also include a large number of military situational awareness satellites and the International Space Station.
Four years ago, DTRA rounded up research into 16 high-altitude nuclear detonations during the Cold War that damaged or destroyed at least eight satellites. Most famously, Telstar 1 -- the world's first communications satellite -- was damaged in 1962 after its transistors were bombarded by electrons released by the 1.4-megaton, 250-mile-high Starfish Prime nuclear test.
While most low-earth-orbit satellites would avoid being immediately knocked out by an EMP, the presence of radiation exposure over the long term is a "serious long-term hazard" that "could seriously hamper any war effort, particularly in remote regions," the agency noted in a 2010 report.
Little is known about effects of EMP at higher altitudes, above 370 or so, or below 60 miles. For a ballistic missile defense system that successfully strikes and detonates a nuclear ICBM at high altitudes, "strategies may risk being designed on the basis of inappropriate levels of nuclear effects, at least for detonations in the upper half of the mid-course battle space," the report added.
The good news is that the agency doesn't think mid- and high-earth orbit satellites are at great risk for any damage beyond a slightly shorter lifespan. "Satellites in MEO or GEO are not at risk to immediate loss from radiation damage resulting from a credible EMP attack anywhere on Earth," the agency concluded.
At high orbits, spy satellites from the National Reconnaissance Office, military communications satellites, and ballistic missile detectors -- plus the Global Positioning System -- are already heavily shielded from radiation. Radiation injected by a weapon at high orbits would also decay within days instead of years like in low orbits, lessening the effect further.
There are several things you could do to make satellites more survivable, though. There's hardening and shielding, which can add weight and cost -- a problem for private companies that own and operate LEO satellites jointly used by the military. The often-misunderstood, $250 million High Frequency Active Auroral Research Program (HAARP) is even used by the Air Force to research how to scrub the magnetosphere of electrons emitted by nuclear weapons that could screw up satellite transistors.
But then there's the practical problem for whoever's doing the nuking which makes the scenario not that plausible. If you’re a rogue dictator with some loose H-bombs, why launch them into space when you could just nuke a city? Either way you've started a nuclear war with the world's most powerful nuclear power. The risk of starting Armageddon is still the same. What makes EMP so different?
Still, you can't fault DTRA for at least being interested in the idea. And on the flip side, there's always the potential for non-nuclear EMP space weapons to get panicky about. Don't lose too much sleep over it, though.