AN INTERNET in orbit. Dynamite and a laser beam. All meant how to secure military communications in space.

SATELLITES are crucial military infrastructure for spying and communications. But they are also vulnerable to attack and disruption.

In November 2021, three months before it invaded Ukraine, Russia fired a missile into a defunct satellite. Then, in October, a Russian diplomat declared even commercial satellites could be legitimate targets.

The Space-Based Adaptive Communications Node (Space-bacn, or “Space Bacon”, to its friends) will, if successful, create a laser-enabled military internet in orbit around Earth by piggybacking on a number of satellites that would have been launched anyway.

Space Bacon is a brainchild of DARPA, the especial projects research arm of the Department of Defence, and is an intriguing orbiting echo of the original, terrestrial ARPANET, which evolved into the internet. [ It was so named at a point in DARPA'S history when the organisation lacked the initial ''D'' for ''defence''.]

The plan is to fit as many newly launched satellites as possible with laser transceivers that will be able to communicate with counterparts as far away as 5,000km. Satellite owners will pay for these transceivers, but will then receive payments from the American government for their use.

'' Zipping the light fantastic '' : Space Bacon promises many benefits. Unlike radio, the normal mode of communication with and between satellites, transmissions by laser beam are hard to intercept and almost impossible to jam.

Indeed, adversaries might not even know when a transmission is taking place, a bonus for operational secrecy.

LASERS also offer far higher data rates than radio waves. Some satellite constellations do already use lasers for communication between members, and these achieve about two gigabits per second [ about 200 times what radio can manage].

DARPA however, has asked Space Bacon's contractors to develop equipment that can transmit, in a single beam, 100 gigabits per second. That is enough for several high-definition movies to be sent in that time.

The ability to hand military information from bird to bird like this - and without the constraints imposed by differences in the communication protocols of the satellites providing the piggyback - will greatly simplify matters.

Individual satellites can download data only when in range of terrestrial antenna belonging to their particular network, or via another member of that network, which is likely to be in a similar orbit.

A satellite in the Space Bacon System, by contrast can hand off data to another, possibly belonging to another operator, in a different orbit. And that satellite may, in turn, hand it to yet another, until a suitable ground antenna is within reach.

At the moment, reporting delays caused by lack of network interoperability mean, say, that a military tank spotted by a satellite may have driven off by the time its location has been received by anyone who could make use of the information. Space Bacon will more or less eliminate this latency.

It will also offer one of the vaunted phases of the original ARPANET design, which the internet inherited. This is automatic rerouting of a message if a node [ ie, a particular satellite or ground station ] is disabled.

Also, by bringing pretty-well every relevant ground station into play, data that are especially sensitive can, as Greg Kuperman, Space Bacon’s programme manager, observes, be routed through antennae in places where attempts to eavesdrop on the final, radio-transmitted, leg of the journey are considered less likely.

The Master Global Essay continues. The World Students Society thanks The Economist.


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