ESA/ATG medialab
We have found thousands of exoplanets, and now it is time to take a closer look. The Characterising Exoplanets Satellite (CHEOPS), a European Space Agency mission, is scheduled to launch from Kourou in French Guiana on 17 December. It will help us understand the exoplanets that have already been discovered.
CHEOPS is a relatively small observatory, measuring about 1.5 metres on each side – in comparison, the Hubble Space Telescope is 13.2 metres long and 4.2 metres across. However, while Hubble performs many different purposes, CHEOPS is much more targeted. It was built specifically to measure the radii of planets for which we already have mass estimates.
That might sound like a very specific mission, but it is a crucial one – when we know both the radius and mass of a planet, we can figure out its density, which gives us a far more precise idea of what it is made of. For example, a planet slightly heavier than Earth could be rocky like our world or, if it has a much bigger radius, could be gaseous like a mini-Neptune.
Advertisement
Read more: We’ve found 4000 exoplanets but almost zero are right for life
The ability to categorise worlds by what they are made of will also help us understand how planets evolve in different environments and determine which exoplanets are most likely to be friendly to life.
After the launch, CHEOPS will head towards its orbit 700 kilometres above Earth’s surface, where it will surf the line between day and night, always pointing away from the sun. This will ensure that it can continuously take pictures of planets in a dark sky.
Over its planned 3.5-year mission, CHEOPS will observe hundreds of worlds we have already seen, and also check those systems for unseen additional planets and moons.
It is the first space telescope designed to study exoplanets rather than just find them, but it won’t be the last: several other planned observatories are set to take even more detailed pictures, including NASA’s enormous James Webb Space Telescope, which is scheduled to launch in 2021.
More on these topics: