Comet Interceptor Approved for Construction

Science & Exploration

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ESA’s Comet Interceptor mission to visit a pristine comet or other interstellar object that has just begun its journey into the inner solar system has been ‘adopted’ this week; the study phase has been completed and, after selection of the spacecraft prime contractor, construction of the mission will begin soon.

Comet Interceptor will share a ride to space with ESA’s Ariel exoplanet mission in 2029. The mission will build on the successes of Rosetta and Giotto, ESA missions that visited both comets with a ‘short period’. While these missions completely changed our understanding of comets, their targets had already orbited the sun many times and therefore had changed significantly since their inception.

Kuiper belt and Oort cloud in context

Comet Interceptor aims to investigate a comet that has spent little time in the inner Solar System, or may be visiting it for the first time. While Rosetta’s target came from the rocky Kuiper belt just beyond Neptune, that of comet interceptor could have come from the vast Oort cloud, more than a thousand times farther from the sun.

Though much rarer, another potential target could be an “interstellar invader” from outside the solar system — something akin to “Oumuamua that unexpectedly flew past the sun in 2017. Studying such an object could provide an opportunity to investigate how comet-like bodies form and evolve in other galaxies.

Comet 67P/Churyumov-Gerasimenko, target of ESA’s Rosetta mission

Comet Interceptor was adopted by ESA at the Agency’s Science Program Committee meeting on June 8. The mission is led by ESA with support from the Japan Space Agency (JAXA).

“The adoption of Comet Interceptor builds on the breakthroughs of our visionary Giotto and Rosetta missions, accelerating us to the next level of comet science,” said Günther Hasinger, ESA’s Director of Science. “It will keep European scientists at the forefront of cometary research and position ESA as a leader in this exciting field.”

Comet Interceptor will consist of a main spacecraft and two probes, which will surround the comet to observe it from multiple angles. In this way, the innovative mission builds a 3D profile of its as-yet undiscovered target. ESA is responsible for the main spacecraft and one of the probes, while JAXA is responsible for the second probe.

“A comet in its first orbit around the sun would contain raw material from the beginning of the solar system,” explains ESA’s Comet Interceptor researcher Michael Küppers. “By studying such an object and sampling this material, we can understand not only more about comets, but also how the solar system formed and evolved over time.”

Travel to a comet

Location of Lagrange point (L2)

Comet Interceptor was presented to ESA in July 2018 and selected in June 2019. It is an example of a ‘fast’ or F-class mission, taking only about eight years from selection to launch. These smaller missions weigh less than 1000 kg.

The mission is expected to be launched in 2029 along with ESA’s exoplanet study Ariel mission. The two missions will travel together to L2 – a location 1.5 million km ‘behind’ the Earth as seen from the sun. There, Comet Interceptor awaits a suitable target. Once one is spotted and selected, the mission continues its journey.

With recent advances in ground-based telescopes, ‘new’ comets are now usually detected more than a year before they get closest to the sun. This is still too short to plan, build and launch a special space mission. But it’s enough time for the ready-made Comet Interceptor to travel from L2 to the comet’s location.

Controlling spacecraft over millions of miles of space is always a challenge, but Comet Interceptor has a truly unique flight profile. Navigating the spacecraft to the target comet, releasing the probes at the right moment and performing a flyby will require steady hands and calm minds from the ESA mission team.

A visionary mission – with benefits in space and on Earth

Artist impression of ‘Oumuamua

The three flight elements – the main spacecraft and two smaller probes – that make up Comet Interceptor will each be equipped with different high-tech instruments that will help us discover more about the dynamic nature of a pristine comet. ESA will lead the development of the main spacecraft and one of the probes, both with unique instruments mainly built by European industry. The other probe is being developed by JAXA.

Comet Interceptor has pioneering goals to characterize the surface composition, shape and structure of a pristine comet for the first time and to investigate the composition of its gas and dust coma. In some cases, this will require existing technologies to be refined, giving a boost to the aerospace and mechanical engineering industries in many ESA member states.

“As with most ESA missions, Comet Interceptor will foster collaboration between different companies, institutions and countries, accelerating the development of innovative technologies that could have completely different applications in the future,” said ESA’s Comet Interceptor project manager Nicola Rando.

Comet Interceptor also contributes to ESA’s planetary defense efforts. We know of nearly 120 comets and more than 29,000 asteroids orbiting the sun close to Earth. By studying these objects, we not only discover secrets of the solar system, but also become better equipped to protect our planet if and when one is discovered on a collision course with Earth. Comet Interceptor joins a fleet of global missions related to planetary defense, including ESA’s Hera mission, which is involved in the world’s first asteroid deflection test.

Nicola concludes: “Having spent the past few years conceiving and developing the Comet Interceptor concept, we are now ready to take the mission to the next phase, select the main contractor and then start the implementation phase.”

For more information, please contact:

ESA Media Relations

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