What would happen if satellite communications were taken down by enemy action during a war?
It’s a question governments and militaries around the world are grappling with, and one of the more surprising answers is to train sailors brought up in a digital world to master extremely analog technology such as the use of sextants to navigate by the stars.
Prof Dale Stephens, from the University of Adelaide, is a co-editor of a new reference book for governments and civilians to understand the “rule of law in space in times of peace, heightened tension, and even armed conflict”, a global collaboration that took more than five years and posed any number of hypothetical scenarios involving space warfare.
“If you bring down the world’s GPS system, that we all rely on, then our digital world becomes sluggish and compromised and doesn’t work,” Stephens says.
“We go back to an analog world. We don’t have the internet. We have analog communications. We use landlines, we watch analog television.”
Australia’s military, like those of every other country, has become increasingly dependent on the global navigation satellite systems (GNSS), which includes GPS and other systems.
The military relies on space for communications, for position, navigation and timing (PNT) information, meteorology, intelligence, surveillance and reconnaissance. Australia now recognises space as an operational domain, alongside air, sea, land and cyber, and has established a Defence space command.
The Australian defence force already offers celestial navigation training and is working on a range of alternative navigation technologies.
It has a “navigate using celestial aids” training unit that includes learning how to construct a sun compass to establish north, south, east and west; identify celestial bodies to determine south and north; and other methods to estimate direction, time, distance and position. Defence did not respond to questions about other fallback measures.
A Defence spokesperson explains: “Royal Australian Navy maritime warfare officers and navigating officers are trained in a variety of navigational techniques including terrestrial and celestial navigation.
“Navigation by means alternate to GPS remains paramount and relevant personnel are trained in these methods from the moment they commence their journey in the Royal Australian Navy.”
The US Navy stopped using celestial navigation in 2006, but brought it back in 2016 amid concerns it was overreliant on GPS, which could be disrupted by Russia or China.
In a Senate hearing last year the US space commander, Gen James Dickinson, said he believed “we will be degraded at some point in the GPS world” and were looking at PNT capabilities. “If you’re on a Navy ship … you have a sextant that you can use,” he said, and departments were making efforts to “kind of go back to how we used to do things”.
In a 2021 US Naval Institute article, US Navy Lt Matthew Homeier wrote that the navy required submarines to carry sextants, but that to use them the boat would have to surface and a sailor would need to carry the fragile apparatus carefully up a ladder, making it “impractical and inefficient”.
UK Royal Navy ships are required to carry a nautical almanac for “emergency celestial navigation”.
Satellites in a legal grey area
The project Stephens worked on is the Woomera Manual on the International Law of Military Space Activities and Operations.
Universities, technical experts, lawyers and others from around the world worked on the book, which was then peer reviewed, and reviewed by 24 states in The Hague as well as the international committee of the Red Cross.
Stephens says they looked at potential military activities on the moon (which will be regulated by the Artemis Accords), weapons in orbit and other subjects, and that satellites were a particular focus that could be a legal grey area.
Several countries have already developed and demonstrated anti-satellite missile technology.
Earlier this month, Russia reportedly disrupted the Starlink satellite internet service that Ukrainian soldiers use to communicate, control drones and gather intelligence. Last year, France accused Russia of sidling one of its satellites up to one of theirs to tap information.
China has demonstrated its ability to “grapple” a satellite and pull it out of orbit. The US has warned that China and Russia are regularly attacking US satellites.
Stephens says the manual clarifies the laws about various anti-satellite technologies (Asats), such as targeting a satellite with a direct ascent missile.
“That is proven technology. It travels faster than a speeding bullet,” he says. “We also looked at co-orbital Asats … where you just ram one of your satellites that’s already in orbit into another one.
“[Then there are] high-energy weapons, lasers and microwave weapons where you don’t have the damage, the debris you’d have from a kinetic weapon – you’d still achieve the military aim without blowing it to pieces.”
The group also looked at “jamming”, a form of electronic interference, and cyber-attacks that can make satellites dysfunction. They looked at instances where Asats might be seen as an armed attack or use of force, and therefore subject to legal ramifications. Currently a patchwork of laws – from the Outer Space Treaty to UN conventions and individual state laws – govern aggression in space.
“Each one fits along a particular point of the spectrum of whether it’s a use of force or an armed attack and that’s relevant to what the victim state can do,” Stephens says.
A “huge” exception, he says, applies to early warning satellites belonging to China, Russia and the US, which would alert them to an imminent nuclear attack.
He says those satellites “sit outside all the other rules” because they are intended to give a nation precious minutes to decide whether to deploy defensive weapons.
Any attack on an early warning satellite would be “a clear indicator the war has begun because they are stopping you seeing what they are about to do”, he says.
