Swarm is a

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 (1205 ...

(ESA) mission to study the

Earth's magnetic field Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magnetic f ...

. High-precision and high-resolution measurements of the strength, direction and variations of the Earth's magnetic field, complemented by precise navigation,

accelerometer An accelerometer is a tool that measures proper acceleration. Proper acceleration is the acceleration (the rate of change of velocity) of a body in its own instantaneous rest frame; this is different from coordinate acceleration, which is accele ...

and

electric field An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field fo ...

measurements, will provide data for modelling the geomagnetic field and its interaction with other physical aspects of the Earth system. The results offer a view of the inside of the Earth from space, enabling the composition and processes of the interior to be studied in detail and increase our knowledge of atmospheric processes and ocean circulation patterns that affect

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologic ...

and

weather Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmosphere, the ...

Overview

The overall objective of the Swarm mission is to build on the experience from the Ørsted and CHAMP missions and to provide the best ever survey of the geomagnetic field (multi-point measurements) and its temporal evolution, to gain new insights into the Earth system by improving our understanding of the

Earth's interior The internal structure of Earth is the solid portion of the Earth, excluding its atmosphere and hydrosphere. The structure consists of an outer silicate solid crust, a highly viscous asthenosphere and solid mantle, a liquid outer core wh ...

and climate. The Swarm constellation consists of three

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...

s (Alpha, Bravo and Charlie) placed in two different

polar orbit A polar orbit is one in which a satellite passes above or nearly above both poles of the body being orbited (usually a planet such as the Earth, but possibly another body such as the Moon or Sun) on each revolution. It has an inclination of about ...

s, two flying side by side at an altitude of and a third at an altitude of .SWARM Technical Annex
2004 The launch was delayed and rescheduled to 12:02:29 UTC on 22 November 2013, from

Plesetsk Cosmodrome Plesetsk Cosmodrome ( rus, Космодром «Плесецк», r=Kosmodrom "Plesetsk", p=kəsmɐˈdrom plʲɪˈsʲet͡sk) is a Russian spaceport located in Mirny, Arkhangelsk Oblast, about 800 km north of Moscow and approximately 200 ...

, Russia. ESA contracted

Astrium Astrium was an aerospace manufacturer subsidiary of the European Aeronautic Defence and Space Company (EADS) that provided civil and military space systems and services from 2006 to 2013. In 2012, Astrium had a turnover of €5.8 billion and 1 ...

to develop and build the three orbiters, while

Eurockot Eurockot Launch Services GmbH is a commercial spacecraft launch provider and was founded in 1995. Eurockot uses an expendable launch vehicle called the Rockot to place satellites into low Earth orbit (LEO). Eurockot is jointly owned by ArianeGroup ...

provided the launch services. Through a Canadian-European partnership, the

Canadian Space Agency The Canadian Space Agency (CSA; french: Agence spatiale canadienne, ASC) is the national space agency of Canada, established in 1990 by the ''Canadian Space Agency Act''. The president is Lisa Campbell, who took the position on September 3, 2020 ...

CASSIOPE Cascade, Smallsat and Ionospheric Polar Explorer (CASSIOPE), is a Canadian Space Agency (CSA) multi-mission satellite operated by the University of Calgary. The mission development and operations from launch to February 2018 was funded through ...

satellite's e-POP instrument suite was formally integrated as the fourth satellite in the Swarm constellation in 2018, joining Alpha, Bravo, and Charlie as Echo.

Scientific objectives

Primary objectives: *

Earth core The internal structure of Earth is the solid portion of the Earth, excluding its atmosphere and hydrosphere. The structure consists of an outer silicate solid crust, a highly viscous asthenosphere and solid mantle, a liquid outer core wh ...

dynamics,

geodynamo In physics, the dynamo theory proposes a mechanism by which a celestial body such as Earth or a star generates a magnetic field. The dynamo theory describes the process through which a rotating, convecting, and electrically conducting fluid can ...

processes, and core- mantle interaction *

Lithospheric A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of up to thousands of years or ...

magnetization and its geological interpretation * 3D

electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allow ...

of the mantle * Currents flowing in the

magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior dynam ...

and

ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an ...

Secondary objectives: * Identification of the

ocean circulation An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, s ...

by its magnetic signature * Quantification of the magnetic forcing of the

upper atmosphere Upper atmosphere is a collective term that refers to various layers of the atmosphere of the Earth above the troposphere and corresponding regions of the atmospheres of other planets, and includes: * The mesosphere, which on Earth lies between the ...

Payload

The payload of the three spacecraft consists of the following instruments: * ''Vector Field Magnetometer'' (VFM): Linear and low-noise measurements of the

vector components. The fluxgate vector magnetometer is similar to the ones in the satellites Ørsted, CHAMP and SAC-C. * ''Absolute Scalar Magnetometer'' (ASM): its main goal is the calibration of the main instrument VFM. It consist in a scalar optically pumped magnetometer based on metastable helium-4 designed by CEA-Leti. * ''Electric Field Instrument'' (EFI): Measurement of ion density, drift velocity and

. * ''Accelerometer'' (ACC): Measurement of non-gravitational accelerations like air-drag, winds, Earth

albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...

and solar

radiation pressure Radiation pressure is the mechanical pressure exerted upon any surface due to the exchange of momentum between the object and the electromagnetic field. This includes the momentum of light or electromagnetic radiation of any wavelength that is a ...

. * ''Laser Range Reflector'' (LRR): Reflecting

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

prism Prism usually refers to: * Prism (optics), a transparent optical component with flat surfaces that refract light * Prism (geometry), a kind of polyhedron Prism may also refer to: Science and mathematics * Prism (geology), a type of sedimentary ...

s as part of the

satellite laser ranging In satellite laser ranging (SLR) a global network of observation stations measures the round trip time of flight of ultrashort pulses of light to satellites equipped with retroreflectors. This provides instantaneous range measurements of milli ...

network.

Mission history

Pre-launch

The three ''Swarm'' satellites arrived at the

in September 2013 to begin final testing before fuelling and incorporation with the

Rokot Rokot (russian: Рокот meaning ''Rumble'' or ''Boom''), also transliterated Rockot, was a Russian space launch vehicle that was capable of launching a payload of into a Earth orbit with 63° inclination. It was based on the UR-100N (SS- ...

launch vehicle.

Launch

The ''Swarm'' constellation was successfully launched aboard Rokot/Briz-KM on 22 November 2013.

Operations

The constellation is controlled by the

European Space Operations Centre The European Space Operations Centre (ESOC) serves as the main mission control centre for the European Space Agency (ESA) and is located in Darmstadt, Germany. ESOC's primary function is the operation of unmanned spacecraft on behalf of ESA and ...

Darmstadt Darmstadt () is a city in the States of Germany, state of Hesse in Germany, located in the southern part of the Frankfurt Rhine Main Area, Rhine-Main-Area (Frankfurt Metropolitan Region). Darmstadt has around 160,000 inhabitants, making it th ...

, Germany. By the beginning of May 2014, Swarm had finished its in-orbit commissioning. Preliminary data indicates that the constellation is performing well as data received closely matches that from a previous German mission, CHAMP. During the commissioning stage problems were discovered with the backup

Magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, o ...

on the "Charlie" satellite, which led to "Bravo" satellite being placed in the lone high altitude orbit (510 km) and "Charlie" joining "Alpha" in the lower tandem orbit (462 km) to improve the resilience of the constellation. Commissioning data also indicated greater noise in data when a satellite was in view of the sun; the current theory is this is caused by differential heating in the satellite, but this has not been confirmed. Overall, the constellation is in good health and, due to accurate orbital insertion, has significant fuel reserves remaining.

Discoveries and applications

In September 2016, scientists published a study that revealed a direct link between GPS blackouts of low-Earth-orbiting satellites and "thunderstorms" in the

. During the first two years of Swarm's operation their GPS connection was broken 166 times. The high-resolution observations from the satellite helped to link these outages to ionospheric thunderstorms 300–600 km in the Earth's atmosphere. In December 2016, scientists announced that, by using data from the Swarm satellites, they had discovered a new feature in the Earth's

outer core Earth's outer core is a fluid layer about thick, composed of mostly iron and nickel that lies above Earth's solid inner core and below its mantle. The outer core begins approximately beneath Earth's surface at the core-mantle boundary and e ...

, a ''jet-stream'' of rapidly moving liquid iron moving at around 50 km per year. In April 2017, Swarm's data was used to confirm that Steve was a previously unrecognized atmospheric phenomenon. In May 2020, Swarm revealed that Earth's magnetic field is gradually weakening in an area stretching from

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

, which might cause technical disturbances in satellites orbiting Earth.

References

External links

ESA web page on the mission

eoPortal page of Swarm
{{Orbital launches in 2013 Earth observation satellites of the European Space Agency Spacecraft launched in 2013 Spacecraft launched by Rokot rockets Geomagnetic satellites