The ''Comet Interceptor'' is a robotic spacecraft mission led by the

European Space Agency , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (120 ...

(ESA) planned for launch in 2029. The spacecraft will be "parked" at the Sun-Earth L₂ point and wait for up to three years for a

long-period comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena a ...

to fly by at a reachable trajectory and speed. The

Principal Investigator In many countries, the term principal investigator (PI) refers to the holder of an independent grant and the lead researcher for the grant project, usually in the sciences, such as a laboratory study or a clinical trial. The phrase is also often us ...

is Geraint Jones, from the

Mullard Space Science Laboratory The UCL Mullard Space Science Laboratory (MSSL) is the United Kingdom's largest university space research group. MSSL is part of the Department of Space and Climate Physics at University College London (UCL), one of the first universities in the ...

in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...

. The maximum cost of the

spacecraft bus A satellite bus (or spacecraft bus) is the main body and structural component of a satellite or spacecraft, in which the payload and all scientific instruments are held. Bus-derived satellites are opposed to specially produced satellites. Bus-d ...

is set at €150M, excluding science instruments and launch services.

Overview

Long-period comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena a ...

s have highly eccentric orbits and periods ranging from 200 years to millions of years, 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 A halo orbit is a periodic, three-dimensional orbit near one of the L1, L2 or L3 Lagrange points in the three-body problem of orbital mechanics. Although a Lagrange point is just a point in empty space, its peculiar characteristic is that it c ...

around the Sun-Earth L₂ point and wait for the discovery of a suitable comet that it can reach for a close flyby. 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 Delta-''v'' (more known as " change in velocity"), symbolized as ∆''v'' and pronounced ''delta-vee'', as used in spacecraft flight dynamics, is a measure of the impulse per unit of spacecraft mass that is needed to perform a maneuver such ...

) within a total mission length of approximately 5 years. The baseline design is

solar electric propulsion Solar electric propulsion (SEP) refers to the combination of solar cells and electric thrusters to propel a spacecraft through outer space. This technology has been exploited in a variety of spacecraft by the European Space Agency (ESA), th ...

. Finding a suitable comet to fly by will rely on ground-based observational surveys such as

Pan-STARRS The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1; obs. code: F51 and Pan-STARRS2 obs. code: F52) located at Haleakala Observatory, Hawaii, US, consists of astronomical cameras, telescopes and a computing facility that is ...

ATLAS An atlas is a collection of maps; it is typically a bundle of maps of Earth or of a region of Earth. Atlases have traditionally been bound into book form, but today many atlases are in multimedia formats. In addition to presenting geograp ...

, or the future

Large Synoptic Survey Telescope The Vera C. Rubin Observatory, previously referred to as the Large Synoptic Survey Telescope (LSST), is an astronomical observatory currently under construction in Chile. Its main task will be carrying out a synoptic astronomical survey, the Le ...

(LSST). 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. There is also the potential of intercepting an

interstellar object An interstellar object is an astronomical object (such as an asteroid, a comet, or a rogue planet, but not a star) in interstellar space that is not gravitationally bound to a star. This term can also be applied to an object that is on an interst ...

passing through the Solar System, if the velocity and direction permit. 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 A coma is a deep state of prolonged unconsciousness in which a person cannot be awakened, fails to respond normally to painful stimuli, light, or sound, lacks a normal wake-sleep cycle and does not initiate voluntary actions. Coma patients exhi ...

." ''Comet Interceptor'' is being developed as ESA's first Fast class (F-class) of the

Cosmic Vision Cosmic Vision is the third campaign of space science and space exploration missions in the Science Programme of the European Space Agency (ESA). Formulated in 2005 as ''Cosmic Vision: Space Science for Europe 2015–2025'', the campaign succee ...

programme. The mission is being planned and developed by a consortium that includes the ESA and Japan's space agency

JAXA The is the Japanese national air and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satellites into o ...

. ''Comet Interceptor'' will share the launch vehicle with ESA's

ARIEL Ariel may refer to: Film and television *Ariel Award, a Mexican Academy of Film award * ''Ariel'' (film), a 1988 Finnish film by Aki Kaurismäki * ''ARIEL Visual'' and ''ARIEL Deluxe'', 1989 and 1991 anime video series based on the novel series ...

space telescope, which is also bound for Lagrange point 2.

Secondary spacecraft

A few weeks 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

. Each of the three spacecraft will sample gas composition, dust flux, density, magnetic fields, and plasma and

solar wind The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the ...

interactions, to build up a 3D profile of the region around the comet.

References

{{Future spaceflights Missions to comets European Space Agency space probes 2029 in spaceflight Cosmic Vision Proposed space probes

Overview

Secondary spacecraft

See also

References