The constellation of Earth-imaging satellites launched yesterday—28 individual sputniks, called “Doves,” each about the size of its namesake and weighing in at a svelte five kilograms—is on its way to the International Space Station. If all goes well, by the end of the month “Flock 1,” as the group is called, will distribute its nanosatellites in Earth orbit, the better to photograph the complete surface of the planet at high resolution 365 days a year. The satellites will provide near-continuous pictures of Earth’s surface at a resolution of three to five meters per pixel.
Planet Labs, the San Francisco start-up that built Flock 1, is one of a growing group of companies and governments launching very small satellites. As their cost and size have plummeted, partly in response to the availability of standardized off-the-shelf components, nanosatellites such as CubeSat, have opened up unprecedented opportunities in remote sensing. Unlike traditional Earth-imaging satellites, which cost millions to build and launch, each of Planet Labs’ diminutive sky cameras, which in its predeployed state resembles a child’s kaleidoscope, comes in at a fraction of that cost.
Planet Labs plans to be the first to capture high-resolution whole-Earth images nearly continuously. (Full disclosure: one of us—Boettiger—serves without remuneration as an advisor to Planet Labs.) Test satellites launched in April and November demonstrated that the company’s engineers can accurately position the orbiters and capture a continuous stream of images with a resolution of three to five meters—fine enough to distinguish individual trees in a rainforest, but not sharp enough to identify a person tending his garden. Whereas most of the nine spectral bands of imagery captured by the National Oceanic and Atmospheric Administration’s Landsat 8, launched in 2013, for example, are delivered at 30-meter resolution, other commercial providers of remote-sensing images, such as Skybox Imaging and BlackBridge (formerly RapidEye), have the capability to deliver much higher resolutions—as fine as one meter per pixel. These companies even offer features such as high-resolution, real-time video. But these satellites are tasked with photographing specific targets, meaning customers rent the use of a satellite (much as one might hire a photographer) to capture detailed images of very specific patches of the globe. Planet Labs executives say that continuous whole-Earth images would have the potential to serve many purposes simultaneously, from a single set of data. “We've become used to having imagery of the entire Earth,” says Tim O’Reilly, of O’Reilly AlphaTech Ventures, one of Planet Labs’s investors. “What we haven't yet understood is how transformative it will be when that imagery is regularly and frequently updated.”
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Planet Labs faces some difficult challenges, not least the engineering required to build, launch, power, position and communicate with a constellation of this size. The company will have to store the equivalent of a 10-terapixel image (roughly one million cell phone images) for each complete image of Earth. The company has already engineered much of the software it needs to stitch the massive number of images collected by its orbiters into a single texture applied to a topographic model of Earth. Unlocking the value of this image will require using image recognition, change detection and other technologies to solve problems in data mining and information extraction. The task combines "science, technology expertise and know-how learned at NASA with a bottoms-up maker's mentality,” says Juan Carlos Castilla-Rubio, CEO of the Planetary Skin Institute and co–chair of the World Economic Forum Global Agenda Council on Measuring Sustainability 2012–14.
Although the technology has many commercial applications, it also offers opportunities for humanitarian purposes. The high frequency of imaging will potentially be useful in detecting global changes in crop cover, construction, animal migrations, pest infestations, surface water, natural disasters, refugee camps, sea ice, pollution, traffic patterns.
