Reading passage
For decades, satellites were among the most expensive machines ever built. A typical Earth-observation or communications satellite could be the size of a bus, weigh several tonnes, and cost hundreds of millions of dollars to design, build, and launch. Because so much money was at stake, every component was tested exhaustively, projects took many years, and a single failure could end an entire programme. Only governments and large corporations could afford to participate. Space, in effect, was closed to almost everyone else.
That began to change in 1999, when professors at Stanford University and California Polytechnic State University published the CubeSat standard. A CubeSat is built from units, each a cube measuring ten centimetres on each side and weighing little more than one kilogram. Units can be combined like building blocks: a '3U' CubeSat, for example, is the size of a loaf of bread. The standard told rocket operators exactly what to expect, which made it far easier to find room for small satellites on launches.
Several technological trends made the revolution possible. The smartphone industry drove the miniaturisation of cameras, batteries, radios, and processors, all of which could be bought cheaply off the shelf rather than custom-made for space. A university team could assemble a working satellite for the price of a family car and test it in a student laboratory. What had once demanded a national budget now fitted inside a shoebox. Software followed the same path. Free operating systems and open-source code replaced custom electronics, and student teams could borrow proven designs from earlier missions instead of starting from nothing. Radio amateurs contributed too, building ground stations that let universities track their craft with equipment costing a few hundred dollars. Several national agencies now run competitions that give winning student teams a free ride into orbit.
Launch costs fell at the same time. Small satellites rarely fly alone; instead they travel as secondary payloads, squeezed into spare capacity on rockets whose main cargo is a larger satellite. Rideshare missions, in which a single rocket releases dozens of small satellites at once, have become routine, dividing the cost of reaching orbit among many customers. Prices that once exceeded twenty thousand dollars per kilogram have fallen to a fraction of that figure. Some new rockets are even designed to serve small satellites exclusively, offering frequent, dedicated flights.
The results have been striking. The American company Planet operates a constellation of more than 200 small imaging satellites that photograph the entire land surface of the Earth every day, allowing farmers to monitor crops, aid agencies to track disasters, and researchers to document deforestation as it happens. Because each satellite is inexpensive, operators can replace them frequently, keeping the fleet's technology current. Other constellations relay data from remote sensors on ships, pipelines, and weather buoys, connecting machines that lie far beyond the reach of mobile networks.
CubeSats have also opened space to newcomers. Hundreds of universities, and even some secondary schools, have built and flown their own satellites, giving students hands-on experience of an entire space mission within a two-year degree. Space agencies now send CubeSats beyond Earth orbit: in 2018, two briefcase-sized craft accompanied a lander to Mars, relaying its signals back to Earth, and several have since travelled to the Moon and near-Earth asteroids.
The boom, however, carries risks. Every satellite launched adds to the congestion of low Earth orbit, where derelict hardware already travels at eight kilometres per second, fast enough to destroy anything it strikes. A major collision could generate clouds of debris that trigger further collisions, a chain reaction known as the Kessler syndrome. Regulators now require operators to dispose of satellites within five years of a mission's end, and most new small satellites are designed to burn up quickly in the atmosphere.
Astronomers raise a different concern: trains of bright satellites crossing the night sky leave streaks on telescope images and may change the character of the night itself. Operators have responded by darkening surfaces and adjusting orbits, though no complete fix exists. None of these disputes has slowed the trend. Tens of thousands of small satellites are planned for the coming decade, and the cheapest ticket to orbit keeps getting cheaper, redrawing the map of who gets to use space.