Comet Interceptor

Comet Interceptor

Mission type	Comet flyby
Operator	ESA / JAXA
Website	www.cometinterceptor.space/mission.html
Mission duration	≈ 5 years
Spacecraft properties
Spacecraft	Comet Interceptor
Launch mass	Approx. 850 kg (1,870 lb). [1]
Start of mission
Launch date	2029 (planned) [2]
Rocket	Ariane 62
Launch site	Kourou ELA-4
Contractor	Arianespace
Flyby of a long-period comet yet to be selected
Cosmic Vision ←  ARIEL ATHENA  →

The Comet Interceptor is a robotic spacecraft mission led by the European Space Agency (ESA) planned for launch in 2029. ^[2] The spacecraft will be "parked" at the Sun-Earth L₂ point and wait for up to three years for a long-period comet to fly by at a reachable trajectory and speed.

The Principal Investigator is Geraint Jones, from the Mullard Space Science Laboratory in the United Kingdom. The maximum cost of the spacecraft bus is set at €150M, excluding science instruments and launch services. ^[1]

Overview

Artist's impression of the Comet Interceptor in space

Long-period comets have highly eccentric orbits and periods ranging from 200 years to millions of years, ^[3] so they are usually discovered only months before they pass through the inner Solar System and return to the distant reaches of the outer Solar System, which is too little time to plan and launch a mission. Therefore, ESA will "park" the Comet Interceptor spacecraft on a stable halo orbit around the Sun-Earth L₂ point and wait for the discovery of a suitable comet that it can reach for a close flyby. ^[4]

The Comet Interceptor mission is unique in that it is designed to encounter an as-yet unknown target, having to wait between 2 and 3 years for a target it can reach with a reasonable change in velocity (delta-v) within a total mission length of approximately 5 years. ^{[4] [5]} The baseline design is solar electric propulsion. ^[4]

Finding a suitable comet to fly by will rely on ground-based observational surveys such as Pan-STARRS, ATLAS, or the future Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST). ^[1] In the case that no long-period comet can be intercepted in time, a backup short period comet (baseline: 73P/Schwassmann–Wachmann) can be studied. ^[4] There is also the potential of intercepting an interstellar object passing through the Solar System, if the speed and direction permit. ^{[4] [6] [7]}

The mission's primary science goal is stated as "to characterise, a dynamically-new comet, including its surface composition, shape, structure, and the composition of its gas coma." ^[8]

Comet Interceptor is being developed as ESA's first Fast class (F-class) of the Cosmic Vision programme. The mission is being planned and developed by a consortium that includes the ESA and Japan's space agency JAXA. Comet Interceptor will share the launch vehicle with ESA's ARIEL space telescope, which is also bound for Lagrange point 2. ^[2]

Secondary spacecraft

Comet Interceptor instruments

One-two days before the comet flyby, the main spacecraft (spacecraft A) will deploy two small probes (B1 and B2) to venture even closer to the target, carrying complementary instrument payloads and to sample the coma. ^{[9] [10]} Each of the three spacecraft will sample gas composition, dust flux, density, magnetic fields, and plasma and solar wind interactions, to build up a 3D profile of the region around the comet. ^[11]

Spacecraft element	Agency	Science payload [12]
A	ESA	CoCa: Visible/near-infrared imager MANIaC: Mass Analyzer for Neutrals and Ions at Comets (mass spectrometer) MIRMIS: NIR and Thermal IR spectral imagers, and MIR spectrometer DFP: Dust, Fields and Plasma
B1	JAXA	HI: Lyman-alpha Hydrogen imager PS: Plasma Suite WAC: wide angle camera
B2	ESA	OPIC: Optical Imager for Comets (Vis/IR) EnVisS: Entire Visible Sky coma mapper DFP: Dust, Fields and Plasma

Timeline

• In 2019, Comet Interceptor has been selected as ESA’s new Fast-class mission ^{[13] [14]}

• In June 2022, the mission was adopted by ESA during the Agency’s Science Programme Committee ^{[15] [16]}

• In December 2022, ESA and OHB have signed a contract to move forward with the design and construction of the spacecraft ^[17]

• In 2023, the Estonian Space Office decided to support the development of OPIC, a camera system designed by the University of Tartu ^{[18] [19]}

• In July 2024, the spacecraft's magnetometer boom was undergoing vibration testing ^[20]

• In November 2024, the Probe B2’s structural qualification model passed all mechanical tests and was pronounced structurally sound ^[21]

• In December 2024, OHB Czechspace in Brno, Czechia assembled the testing article of the dust shield before transporting it to IABG test facilities in Germany. ^{[22] [23]}

See also

• Astronomy portal
• Spaceflight portal

• ARIEL – Launching on the same rocket
• List of European Space Agency programmes and missions

References

1. Jones, Geraint; Snodgrass, Colin (29 January 2019). Comet Interceptor: A proposed ESA mission to an ancient world (PDF). 20th Meeting of the NASA Small Bodies Assessment Group (SBAG). Houston, TX: Lunar and Planetary Institute . Retrieved 15 December 2022.
2. "Comet Interceptor construction moves forward". ESA . 15 December 2022. Retrieved 15 December 2022.
3. "Small Bodies: Profile". JPL . NASA. 29 October 2008. Archived from the original on 30 April 2013. Retrieved 11 August 2013.
4. Jones, Geraint (2 June 2019). "Comet Interceptor - Executive Summary" (PDF). Comet Interceptor Consortium. ESA . Retrieved 15 December 2022.
5. "Comet Interceptor - Mission". Comet Interceptor Consortium. ESA . Retrieved 1 July 2019.
6. O'Callaghan, Jonathan (24 June 2019). "European Comet Interceptor Could Visit an Interstellar Object". Scientific American . Retrieved 15 December 2022.
7. Gough, Evan (29 June 2019). "Meet the Comet Interceptor. It'll Wait Patiently In Space for a Comet, Then Pounce On It". Universe Today . Retrieved 15 December 2022.
8. "Comet Interceptor - Science". Comet Interceptor Consortium. ESA . Retrieved 1 July 2019.
9. "Comet Interceptor factsheet". www.esa.int.
10. Lakdawalla, Emily (21 June 2019). "ESA to Launch Comet Interceptor Mission in 2028". The Planetary Society . Retrieved 15 December 2022.
11. Rabie, Passant (21 June 2019). "A Triple-Threat 'Comet Interceptor' Could Explore an Undiscovered Space Object". Space.com . Retrieved 15 December 2022.
12. "Comet Interceptor's spacecraft and instruments". www.esa.int.
13. "Comet Interceptor concept". www.esa.int. Retrieved 2025-03-16.
14. Snodgrass, Colin; Jones, Geraint H (2019). "The European Space Agency's Comet Interceptor lies in wait". Nature Communications. 10 (1). doi:10.1038/s41467-019-13470-1. ISSN   2041-1723. PMC   6882810 . PMID   31780664.
15. "Comet Interceptor approved for construction". www.esa.int. Retrieved 2025-03-16.
16. "ESA Gives Green Light on its Comet Interceptor Mission". Universe Today. Retrieved 2025-03-16.
17. "Comet Interceptor construction moves forward". www.esa.int. Retrieved 2025-03-16.
18. "Estonia pioneers instrument for Comet Interceptor mission through Prodex". www.esa.int. Retrieved 2025-03-16.
19. Dorminey, Bruce. "Estonia Building Imager For ESA Mission To Intercept Long-Period Comet". Forbes. Retrieved 2025-03-16.
20. "Comet Interceptor's boom gets shaken, not stirred". www.esa.int. Retrieved 2025-03-16.
21. "Comet Interceptor's probe proves structurally sound". www.esa.int. Retrieved 2025-03-16.
22. "OHB Czechspace is assembling the Comet Interceptor dust shield". OHB Czechspace. Retrieved 2025-03-16.
23. "V Brně se chystá konstrukce pro misi Comet Interceptor – Kosmonautix.cz" (in Czech). Retrieved 2025-03-16.