The European Space Agency (ESA) plans to launch a unique comet-hunting mission in 2029.
The mission, called Comet Interceptor, was approved on Wednesday June 8 at the meeting of ESA’s Scientific Program Committee. It will be a collaboration between ESA and the Japan Aerospace Exploration Agency (JAXA).
The mission will consist of three probes – the main spacecraft and two small satellites – which will be launched into space with Europe exoplanet hunter Arielle.
The unusual thing about Comet Interceptor is that it won’t know its target until launch. The probe will move to the Point of Lagrange 2 (L2), a gravitationally stable point 930,000 miles (1.5 million km) from Earth in the direction away from Sun.
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L2 is one of five points between the Earth and the sun where the gravitational forces of the two bodies create balanced conditions. A spacecraft in this region orbits the sun in sync with the Earth while being shielded from the sun’s glare, making this region a sought-after destination for astronomy missions. (The NASA James Webb Space Telescope is one of the residents of L2.)
For Comet Interceptor, L2 will only be a temporary destination. The spacecraft will wait there for a single target to arrive inside solar systemeither a comet from the periphery of the solar system, or an even more distant object, from interstellar space, such as the famous ‘Oumuamuawhich passed 15 million miles (24 million km) from Earth in 2017.
ESA made headlines in 2014 with its Mission Rosettawho placed the Philae Lander on the surface of Comet 67P. In 1986, ESA’s Giotto spacecraft made the first-ever close observations of a comet when it flew past the famous Haley’s Comet. These comets, however, are so-called short-period comets that regularly visit the inner solar system and have flown close to the sun many times before. Each encounter with the sun changes the comet’s chemistry, the ESA said in a statement yesterday, making it less and less representative of the chemical state of the young solar system.
“A comet on its first orbit around the sun would contain unprocessed material from the dawn of the solar system,” said Comet Interceptor study scientist Michael Küppers at ESA. in the statement (opens in a new tab). “Studying such an object and sampling this material will not only help us better understand comets, but also how the solar system formed and evolved over time.”
The ESA expects Comet Interceptor won’t have to wait too long for an exciting target to appear, as new comets are currently being discovered at the rate of at least one per year. Such a time frame would be too short to build and launch a dedicated spacecraft. Comet Interceptor, however, will be able to meet the visitor quickly.
Once Comet Interceptor hits its target, the three spacecraft will separate and image the body in sync from multiple angles to create a three-dimensional profile, the ESA said in the release.
ESA will build the main spacecraft and one of the auxiliary probes, while JAXA, which landed the spacecraft on two separate asteroids with the Hayabusa 1 and Hayabusa 2 missions, will be responsible for the second smallest satellite.
Each of the probes will be equipped with different instruments to analyze the composition, shape and structure of the comet’s surface as well as the dust and gas from its coma, the tail-like cloud emanating from the surface.
The three satellites will together weigh less than 2,200 pounds (1,000 kilograms), the ESA said.