Constellation of satellites will provide frequently updated images of Earth

MIT Technology Review : Planet Labs, based in San Francisco, California, plans to launch a constellation of 28 CubeSats on an Antares rocket as early as December. Each of the 10-cm³ satellites will take medium-resolution images of Earth. At that resolution, objects at least 3–5 m wide should be visible. Because of the number of satellites, Planet Labs will be able to take pictures more frequently than current systems can, which will be useful for updating online maps and for environmental monitoring. Orbiting at an altitude of 400 km, the satellites will form a ring on a tilted axis around Earth. The CubeSats, which have no engines, will be powered by solar panels. The company says that they should stay in orbit for 2 to 5 years before atmospheric drag causes them to fall back to Earth. Three ground stations will receive and process the images and put them online for customers to use. Some of the company’s claims have been questioned, however, particularly its prediction of the satellites’ lifespan and ability to handle the large amounts of data that will be generated.