European space scientists are asking for help from the public to detect signs of activity on a comet.
For two years, between 2014 and 2016, the European Space Agency has Rosetta spacecraft caught up to the comet 67P / Churyumav-Gerasimenko, also known as simply 67P. This ambitious mission was the first to hit a comet and stay with it as it swung past the sun. It was the first opportunity to observe in detail how a comet produces its signature tail.
Comets are extremely old solar system objects made of a combination of rock and ice, loosely assembled into strangely shaped objects just a few kilometers across. 67P is about three times five kilometers and shaped like a rubber duck.
Most comets are found in the cold depths of space outside Neptune where they remain silent and frozen. But every now and then one of them walks inwards towards the sun. As it approaches the inner solar system, the heat of the sun evaporates its ice, and water vapor and dust rise from the surface to form the long beautiful tails that we sometimes see draped over our sky on earth.
67P has an orbit that only takes it as far as Jupiter. As a result, it makes repeated visits to the inner solar system every 6.5 years, making it a good target for study. Other familiar visiting comets have much longer orbits. The most famous – Halley’s comet – takes about 75 years on its journey around the sun and takes it as far as Pluto.
During her mission, Rosetta took almost 100,000 images of the entire surface of the comet. Now the space agency is asking for the public’s help to go through them to help detect any changes that occurred when it followed the comet around the sun.
It turns out that the human eye is the best tool for picking out subtle changes in images taken from the spacecraft. Images of the comet are variable due to the ever-changing vantage point and the illumination of the comet. This makes it difficult to automate the process of observing the comet because computers cannot see the difference between changing lighting and perspective and actual changes in the comet. The human eye and brain are still unsurpassed in this type of pattern recognition task.
Uses a program called ZoouniversumFor example, people can examine before and after images of a region on the comet and note any differences they see.
Some of the changes are small. Maybe a new crack occurs, or a stone changes position due to material eroding under it. Volunteers need to look closely and carefully, like the challenges in magazines that give the reader the task of identifying the differences between two almost identical photos or drawings.
The point of the project is to determine exactly how a comet loses ice and dust, where the material comes from – whether it comes straight from the surface or out through valves – and how much the comet is affected by the sun’s heat.
Researchers hope that this will provide information about the life cycle of a comet, especially one like 67P that makes regular return visits. These visits will eventually erode all the ice from the comet’s mass, reducing it to a flying pile of debris that no longer develops a tail.
Comets have been the subject of lore for centuries, creating both fear and fascination. Now you have the opportunity to contribute to real science and get up close with one of these dazzling celestial visitors from space.