Swarm is a

European Space Agency The European Space Agency (ESA) is a 23-member International organization, international organization devoted to space exploration. With its headquarters in Paris and a staff of around 2,547 people globally as of 2023, ESA was founded in 1975 ...

(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 structure of Earth, Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from ...

. 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 device that measures the proper acceleration of an object. Proper acceleration is the acceleration (the rate of change (mathematics), rate of change of velocity) of the object relative to an observer who is in free fall (tha ...

and

electric field An electric field (sometimes called E-field) is a field (physics), physical field that surrounds electrically charged particles such as electrons. In classical electromagnetism, the electric field of a single charge (or group of charges) descri ...

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 a region, 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 meteoro ...

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 cloud cover, cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmo ...

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 and climate. The Swarm constellation consists of three

satellite A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scient ...

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 abo ...

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, Russia. ESA contracted Astrium to develop and build the three orbiters, while Eurockot provided the launch services. Through a Canadian-European partnership, the

Canadian Space Agency The Canadian Space Agency (CSA; ) is the national space agency of Canada, established in 1990 by the ''Canadian Space Agency Act''. The President of the Canadian Space Agency, president is Lisa Campbell (civil servant), Lisa Campbell, who took ...

's CASSIOPE 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 dynamics, geodynamo processes, and core- mantle interaction * Lithospheric magnetization and its geological interpretation * 3D

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

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 Dynamo ...

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 ...

Secondary objectives: * Identification of the ocean circulation by its magnetic signature * Quantification of the magnetic forcing of the upper atmosphere

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 fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...

and solar radiation pressure. * ''Laser Range Reflector'' (LRR): Reflecting

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

prisms as part of the

satellite laser ranging Satellite laser ranging (SLR) is a method to measure the distance to satellites in a geocentric orbit. It consists of an astronomical observatory equipped with a laser that sends ultrashort pulses of light. The pulses hit the satellite and boun ...

network.

Mission history

Pre-launch

The three ''Swarm'' satellites arrived at the Plesetsk Cosmodrome in September 2013 to begin final testing before fuelling and incorporation with the Rokot 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 in

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 the ...

, 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, ...

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 at altitudes of 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 Earth's inner core, inner core and below its Earth's mantle, mantle. The outer core begins approximately beneath Earth's surface ...

, 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. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

, 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