Satellites: Our invisible infrastructure

‘Space’, in the context of geopolitics, does not mean stars and planets. It does not mean astronauts nor the Moon, except for their symbolism and speculative future potential. Policy statements often group ‘space’ and ‘cyberspace’ together in the same sentence for good reason: in strategic terms, space is primarily a realm of information, and the pieces of equipment that transmit it—satellites. 

What is a satellite?

A satellite is any piece of equipment placed into orbit around Earth. They are a diverse bunch: the smallest not much larger than a laptop, the largest the size of a bus. They range in cost from a few hundred thousand dollars for a low-spec ‘cubesat’ to upwards of half a billion for a GPS satellite.

The stereotypical image of a satellite is generally accurate: a shiny metal box with solar panel ‘wings’ and a communication dish—shiny to regulate its temperature, boxy because it needn’t be aerodynamic, solar panelled because nobody can reach it to replace its batteries, and equipped with a communication dish because a satellite’s main and often only function is to transmit data. (In the latter respect, satellites resemble telegraph poles more closely than aircraft.)

Satellites are disposable. Servicing and repairing them is usually physically impossible and always prohibitively expensive. So they are built to last—built to continue working, often for a decade or more, in a radioactive environment and amid temperatures hotter and colder than anywhere on earth.

What do satellites do?

Most traffic between earth and space takes the form not of rockets but of electromagnetic waves carrying data. The function of satellites is to transmit this data, and occasionally to create it.

Most satellites do one of three things: telecommunications, Earth observation, and global positioning.

As a rule of thumb, Earth observation satellites are in low orbits, where they are closer to the things they want to look at. Telecommunications satellites are in high orbits so that they can ‘see’ (and communicate with) larger areas of Earth at any given time, and global positioning satellites are in medium orbits where few other satellites go.

Telecommunications satellites are the most ubiquitous and account for the lion’s share of the space economy. Their functions include television broadcasting (the most lucrative segment of the entire space sector) and two-way voice and data transmission, with broadband internet the fastest-growing segment. Military uses of satellite communication include piloting drones and communicating securely with forces in the field, making satellites the nerve system of a modern military. In a conflict between advanced military powers, neutralising the adversary’s communication satellites would be a high priority for both sides.

Earth observation (or ‘remote sensing’) includes spy satellites and weather satellites, the latter increasingly relevant to national security as extreme weather events grow more frequent. 

Satellites can ‘see’ parts of the electromagnetic spectrum that the human eye cannot. They can penetrate cloud cover using radar, and they can detect changes in temperature over large areas and changes in foliage (including crops) that are invisible to the human eye.

Commercial satellite operators sell imagery of ever-rising quality, giving buyers access to capabilities that not long ago were the exclusive and highly classified preserve of a handful of governments. This now allows routine open-source imagery analysis of, for instance, North Korea’s nuclear programme and China’s island-building in the South China Sea. Citizen activist groups like Bellingcat have used commercial satellite imagery to expose corruption and human rights abuses.

For decades, governments have used remote sensing satellites to verify compliance with arms control treaties, but the most strategically sensitive of all are the early warning satellites that alert governments to the launch of ballistic missiles by detecting the heat given off when they ignite. Because these satellites are the first line of defence against nuclear attack, interfering with another country’s would be reckless.

The US military developed global positioning satellites for locating friends and targeting foes. They underpin satellite navigation and also carry highly accurate atomic clocks whose signals are used for the high-precision time-stamping of transactions in global financial markets. They are the satellites most integral to the functioning of the global economy and would cause widespread and immediate disruption if they suddenly went offline.

The Global Positioning System (GPS) is the most accurate and widely used. It provides an unencrypted signal free of charge to anyone worldwide, but the US Space Force controls the satellites themselves, so Russia, China, and Europe have built duplicate systems to maintain strategic independence. 

Invisible infrastructure

Satellites are a bigger part of our lives than most of us realise. We rarely notice them in the sky, but we take their invisible presence for granted whenever we check the weather forecast, read news about a drone strike or ask Google Maps for directions. Most of us would be lost without them. Literally.