Farther south in Mountain View, Skybox captures high-resolution imaging data from its first satellite in orbit as it prepares another 23 to launch in the coming years. Some things, though, can be shrunk only so far and larger satellites are needed for a telescope to obtain the higher resolutions required for the firm’s analysis. While Skybox’'s minisatellites weigh around 100kg, a fairly common size for small satellites, the firm proved its concept to investors using CubeSats. “Being able to put something in space at very low cost allows you to demonstrate the technology to get more money,” says Dan Berkenstock, one of the company’s founders.
The CubeSat specification came out of the academic world in the late 1990s. Bob Twiggs, then at Stanford University and now at Morehead State University, was frustrated by long delays on a large-satellite programme and set about thinking how much satellite capability might be crammed into a much smaller craft that could be launched cheaply. Space launches usually comprise one or more primary payloads and require ballast to balance the rocket. CubeSats, reasoned Mr Twiggs, could take the place of some of this ballast, so long as they did not jeopardise the main mission. The optimum size Mr Twiggs came up with was based on a box used to display Beanie Babies. Later, with Jordi Puig- Suari of California Polytechnic State University, it was turned into a full specification. Mr Twiggs also developed the 5cm PocketQube, which has a maximum weight of 180 grammes.
Small satellites benefit from the constant improvements in price and performance being achieved by the consumer- electronics industry, particularly in smartphones. A typical phone is now likely to contain an accelerometer to measure how fast it is moving, a magnetometer to detect magnetic fields and provide a compass reading, a GPS receiver to pick up satellite data, multiple radios, a gyroscope to measure its position, a barometer to detect pressure, two cameras and much more.
Last year the world’s first “phonesat” went into orbit. It was a Google Nexus One smartphone incorporated into a three- unit CubeSat called STRaND-1. This was built by Surrey Satellite Technology, a British firm that specialises in small satellites and which is part of the European Airbus group. The idea was to test the components of the smartphone ina space environment. The phone was loaded with a number of experimental apps for such things as taking photographs and recording magnetic fields during orbit.
Smartphones and other consumer electronics provide a wealth of ready-made technologies that can enable a CubeSat to perform many of the functions of a satellite a hundred times heavier and much larger, but at substantially less cost. Including the launch, a nanosat of CubeSat dimensions might cost $150,000-1m, rather than $200m-1 billion for a full- sized one.
Low cost and a tolerance of less-stringent standards allow multiple nanosats to be built faster. This allows for a higher risk of failure. Nanosats have a relatively short life, which might be no more than a year or two in low-Earth orbit before re-entering the atmosphere and burning up. Planet Labs, for one, expects to replace some of its nanosats with new versions every year.
Into space in a flash
In an industry in which preparing some missions has taken decades, the speed at which nanosats can be developed and put into orbit makes the biggest in the space business take notice. NASA has also found ways to leverage the consumer-electronics industry, says Bruce Yost of the space agency’s Ames Research Centre in California. His group (some former members of which founded Planet Labs) has launched five phonesats and is now planning a small fleet of them to experiment with communications between satellites.
Nanosat parts are readily available to researchers. One supplier, Pumpkin, operates from a residential San Francisco neighbourhood. Andrew Kalman, its founder, started in 2000 selling standard components that Mr Twiggs and his colleagues at Stanford needed. Pumpkin now sells items ranging from brackets for a few hundred dollars up to complete systems for hundreds of thousands of dollars. The company has also supplied America’s National Reconnaissance Office with 12 three-unit CubeSats to help the agency demonstrate the technology.
Although many satellites already circle the globe taking pictures, some of the images may not be updated for days, months or even years. Commercial services can provide relatively rapid satellite images on demand, a number of them taking pictures down to a resolution of 50cm (ie, 50cm x 50cm per pixel, the legal limit in America for commercial satellites, although military ones can peer closer). But such satellites may cover only part of the globe each day. Once their fleets are complete, Planet Labs will offer images with resolutions of between 500cm to 300cm and Skybox, with its bigger minisatellites, 90cm. The companies will provide pictures that can be updated in hours for a variety of scientific and commercial applications.
They could, for instance, be used to track environmental conditions, illegal tree-felling or changes in the course of rivers—which, even in their initial deployment, Planet Labs has discovered happen surprisingly often. The frequency of
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