This month the skies became fuller with Earth observation satellites.  Google added four new SkySat satellites on September 15, while Planet added eight more Doves to its collection this month.  Both companies are building large constellations that will provide near round-the-clock coverage of the Earth's surface, feeding the imagery into huge databases for numerous commercial and not-for-profit ventures.

The four SkySat satellites, constructed for and operated by Google's Terra Bella subsidiary, were put into orbit by a Vega rocket launched from Europe's Guiana Space Center in French Guiana.  Built by Space Systems Loral, each satellite weighs in at around 240 pounds and will deliver 90 centimeter resolution for black and white images and 2 meter resolution for color and video.  

Terra Bella, founded in 2009, views itself not as a traditional “satellite” company, but a Big Data shop, using lower-cost small satellites simply as the means to collect geospatial information that can be used to provide insight into everything from ships moving in and out of a particular port – leading to key measurements on the flow of goods and commodities and supply chain improvements – to observation of gold mining activities in Mongolia.  

Terra Bella's Big Data imagery provides information about change over time, both natural and man-made, with its satellites constantly photographing the Earth. The company now has seven satellites in orbit and will add another six to its constellation in early 2017 with a launch on a U.S. rocket from Vandenberg Air Force Base.   In addition, there are another eight satellites on order that should ultimately provide the company with the ability to get a picture of anywhere on earth in less than two hours.

Planet's smaller Dove satellites added to its constellation entered orbit by way of the International Space Station, with a total of 8 satellites deployed this week through a station airlock coming up on a March cargo flight. Each satellite at 10 by 10 by 30 centimeters in size would be around the size of a bread box (look it up Millennial and younger folks), weighs under 10 pounds and provides resolution between 3 to 5 meters.  

Dove satellites are essentially cheap and disposable, with an expected orbital lifetime of about a year before falling back to Earth and burning up.  The company has so far put a total of 133 into orbit with 50 to 60 currently in operation, with the next generation of 100 to go up in about a year.  Each satellite takes about a week to build.

With so many satellites, Planet is collecting multiple terabytes of imagery per day. Customers can search and analyze data through web interface or use REST APIs to build more sophisticated reusable.  Developers and potential customers also have open access up to two GB of commercial imagery of California under a Creative Commons License, so they can experiment with existing data and create new applications.

At three to five meter resolution, Planet's view of the world is less granular than Terra Bella's, but still more than good enough to use for agricultural, energy, infrastructure, finance, forestry, mapping, and environmental monitoring.  Planet has over 100 customers, including a recent deal with geo-analytics firm Orbital Insight.   Using Planet's and other satellite data, Orbital Insight uses a combination of cloud computing, big data analysis, and machine learning to provide insights on metrics such as U.S. retail traffic, world oil traffic,  global water reserves, and China's economic development.