Monitoring Change, Above and Below
Since 1610, when Galileo first pointed a telescope towards the night sky, astronomers have been observing the Universe using all the means provided by technology.
About twenty years ago, scientists from multiple countries decided to join forces to build a new type of telescope and create a gigantic map of the sky, revealing hundreds of millions of stars and galaxies. This project, the Sloan Digital Sky Survey, which started its operations around 2000, connected a specially designed telescope to the largest digital camera built at the time. As a result, in its first few weeks, this machine collected more data than had been amassed in the entire history of astronomy. Since then, the telescope has been operating almost continuously.
While astronomers have been looking up, observing the sphere of the sky, orbiting satellites have been pointed downward, attempting to image the sphere of Planet Earth. Interestingly, these two groups of people share many tasks and challenges. They just happen to look in opposite directions. First, they both have to observe through the atmosphere — clouds are not their friends, they take pictures using both visible and near-infrared light and they are aiming (for different reasons) at mapping their respective sphere with about 10 trillion pixels.
The detailed maps they created for the Earth and the sky have revolutionized our knowledge of the world we live in. But what is even more interesting is to realize that this revolution is about to be taken one step further: these static maps will soon evolve into movies, showing us how things change from one day to another — both on the Earth and in space.
By launching a flock of 100 nanosatellites, Planet Labs is on its way to image the entire Earth once a day, revealing changes in vegetation, the construction of new buildings, traffic, etc. Similarly, astronomers are preparing the next survey of the sky with the Large Synoptic Survey Telescope which is being built in Chile. This telescope will image the entire night sky every three days for ten years. From one night to the next, it will see more than 10 million objects changing. Exploding stars will suddenly appear, asteroids will move, hot gas accreting onto black holes will shine and then disappear, etc. The Universe is not a quiet place and seeing all these changes will be fascinating.
Once again these two communities of scientists and engineers are facing the same challenges: how can we handle so much data? How can we detect interesting changes happening in unexpected places? Whether it is about detecting new buildings or new stars, many of the questions emerging are calling for similar answers, skills and data analysis techniques.
Planet Labs recently launched its Ambassador Program, allowing scientists to access and analyze its truly unique imaging data. This is a fantastic opportunity for collaborations between researchers from very different fields. The exploration of large datasets is often limited by our own imagination, not by the data. It will be fascinating to see all the projects emerging from this opportunity. The more we collaborate, the better we will be able to understand the world we live in.
Decades ago, Carl Sagan wrote that “Somewhere, something incredible is waiting to be known”. Seeing the Earth and space changing globally on a daily basis is something we have not yet experienced, and no one really knows what we will be able to see and discover.
We are about to enter a new phase of exploration of the Earth and space. This is an exciting time.
This piece was written by Brice Ménard, Professor of Astrophysics at Johns Hopkins University and Planet Labs Ambassador.
