Magnetometer (MAG) is an instrument suite on the ''Juno'' orbiter for planet

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...

. The MAG instrument includes both the Fluxgate Magnetometer (FGM) and Advanced Stellar Compass (ASC) instruments. There two sets of MAG instrument suites, and they are both positioned on the far end of three solar panel array booms. Each MAG instrument suite observes the same swath of Jupiter, and by having two sets of instruments, determining what signal is from the planet and what is from spacecraft is supported. Avoiding signals from the spacecraft is another reason MAG is placed at the end of the solar panel boom, about 10 m (33 feet) and 12 m (39 feet) away from the central body of the ''Juno'' spacecraft. The MAG instrument is designed to detect the

magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...

of Jupiter, which is one of the largest structures in the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...

. If one could see Jupiter's magnetic field from Earth, it would appear five times larger than the

full moon The full moon is the lunar phase when the Moon appears fully illuminated from Earth's perspective. This occurs when Earth is located between the Sun and the Moon (when the ecliptic coordinate system, ecliptic longitudes of the Sun and Moon opp ...

in the sky despite being nearly 1700 times farther away. Jupiter's internal magnetic field prevents the

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 sola ...

, a stream of ionized particles emitted by the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

, from interacting directly with its atmosphere, and instead diverts it away from the planet, effectively creating a cavity in the solar wind flow, called a magnetosphere, composed of a

plasma Plasma or plasm may refer to: Science * Plasma (physics), one of the four fundamental states of matter * Plasma (mineral), a green translucent silica mineral * Quark–gluon plasma, a state of matter in quantum chromodynamics Biology * Blood pla ...

different from that of the solar wind. Mission goals: * map the magnetic field of Jupiter * determine the dynamics of Jupiter's interior * determine the three-dimensional structure of the polar magnetosphere and its

aurora An aurora (plural: auroras or aurorae), also commonly known as the polar lights, is a natural light display in Earth's sky, predominantly seen in high-latitude regions (around the Arctic and Antarctic). Auroras display dynamic patterns of bri ...

s. Jupiter has the strongest and biggest magnetic fields known to exist in the solar system. Studying these fields is one of the goals of the ''Juno'' mission, and in particular the task rests on the Magnetometer instruments. MAG measures the field about 60 times per second, and records the direction and strength of the field. MAG collected data on Earth during its 9 October 2013 flyby en route to Jupiter (this was a

gravity assist In orbital mechanics and aerospace engineering, a gravitational slingshot, gravity assist maneuver, or swing-by is the use of the relative movement (e.g. orbit around the Sun) and gravity of a planet or other astronomical object to alter the p ...

maneuver, but also was to collect data). Another advantage to studying Jupiter's field is that on Earth, crustal magnetism interferes with measurements of the field generated deep in the core, partially shielding it from measurements. On Earth the field is generated by spinning liquid iron, whereas on Jupiter is generated by hydrogen. Jupiter is mostly hydrogen (about 90%), and as it compresses from gravity it turns conductive in a special form. However, it is not known if farther in, where it should compress into metallic form, the hydrogen continues to conduct electricity. That is one of the questions ''Juno'' may answer. In addition to studying Jupiter, the MAG also returned data on the Earth's magnetosphere. The MAG instrument was delivered to

Lockheed Martin Space Systems Lockheed Martin Space is one of the four major business divisions of Lockheed Martin. It has its headquarters in Littleton, Colorado, with additional sites in Valley Forge, Pennsylvania; Sunnyvale, California; Santa Cruz, California; Huntsville ...

' facility in Denver, Colorado, United States for integration into the ''Juno'' spacecraft by NASA's Goddard Spaceflight Center (GFSC) in October 2010. MAG was overall designed and built at the NASA Goddard Space Flight Center (GFSC) in Greenbelt, Maryland. The Advanced Stellar Compass was built and contributed by the

Technical University of Denmark The Technical University of Denmark ( da, Danmarks Tekniske Universitet), often simply referred to as DTU, is a polytechnic university and school of engineering. It was founded in 1829 at the initiative of Hans Christian Ørsted as Denmark's fi ...

. (Technical University of Denmark, or in Danish ( da, Danmarks Tekniske Universitet) commonly known as DTU) The FGM and ASC were turned on in late August after ''Juno''s launch on 5 August 2011. The ASC allow a very precise determination of the magnetometers orientation in space. They are

star tracker A star tracker is an optical device that measures the positions of stars using photocells or a camera. As the positions of many stars have been measured by astronomers to a high degree of accuracy, a star tracker on a satellite or spacecraft may ...

s that take a picture of the sky, then compare those images to a catalog of star maps to allow the orientation to be determined. The fluxgate magnetometer (FGM) is similar to previous instruments flown on spacecraft like the Voyagers,

Magsat Magsat (Magnetic field Satellite, Applications Explorer Mission-C or AEM-C or Explorer 61) was a NASA/USGS (United States Geological Survey) spacecraft, launched on 30 October 1979. The mission was to map the Earth's magnetic field, the satelli ...

, Active Magnetospheric Particle Tracer Explorers,

Mars Global Surveyor ''Mars Global Surveyor'' (MGS) was an American robotic space probe developed by NASA's Jet Propulsion Laboratory and launched November 1996. MGS was a global mapping mission that examined the entire planet, from the ionosphere down through the a ...

, etc. This style of FGM uses twin wide-range, triaxial flux gate sensors mounted far away from the spacecraft body in which the magnetic flux is periodically switched (hence the ame flux-gate). Two FGM's are used so the separate readings can be combined to make the magnetic field calculation. MAG has two vector fluxgate magnetometers supported by advanced star trackers. The star tracking system allows the orientation of the FGM to be calculated and determined more accurately enhancing the usefulness of the FGM readings. Jupiter's magnetic fields were previously observed in the 1970s with ''

Pioneer 10 ''Pioneer 10'' (originally designated Pioneer F) is an American space probe, launched in 1972 and weighing , that completed the first mission to the planet Jupiter. Thereafter, ''Pioneer 10'' became the first of five artificial objects to ach ...

'' and ''

Pioneer 11 ''Pioneer 11'' (also known as ''Pioneer G'') is a robotic space probe launched by NASA on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, solar winds, and cosmic rays. It was the first probe to encounter ...

'', and ''

Voyager 1 ''Voyager 1'' is a space probe launched by NASA on September 5, 1977, as part of the Voyager program to study the outer Solar System and interstellar space beyond the Sun's heliosphere. Launched 16 days after its twin ''Voyager 2'', ''Voya ...

'' and ''

Voyager 2 ''Voyager 2'' is a space probe launched by NASA on August 20, 1977, to study the outer planets and interstellar space beyond the Sun's heliosphere. As a part of the Voyager program, it was launched 16 days before its twin, ''Voyager 1'', on a ...

''. Magnetometers related to ''Juno'' include ones on ''

MAVEN MAVEN is an American spacecraft orbiting Mars to study the loss of its atmospheric gases to space, providing insight into the history of the planet's climate and water. The spacecraft name is an acronym for "Mars Atmosphere and Volatile Evolu ...

'', MGS, Voyager, AMPTE,

GIOTTO Giotto di Bondone (; – January 8, 1337), known mononymously as Giotto ( , ) and Latinised as Giottus, was an Italian painter and architect from Florence during the Late Middle Ages. He worked during the Gothic/Proto-Renaissance period. Giot ...

CLUSTER may refer to: Science and technology Astronomy * Cluster (spacecraft), constellation of four European Space Agency spacecraft * Asteroid cluster, a small asteroid family * Cluster II (spacecraft), a European Space Agency mission to study t ...

Lunar Prospector ''Lunar Prospector'' was the third mission selected by NASA for full development and construction as part of the Discovery Program. At a cost of $62.8 million, the 19-month mission was designed for a low polar orbit investigation of the Moon, ...

, ''

MESSENGER ''MESSENGER'' was a NASA robotic space probe that orbited the planet Mercury between 2011 and 2015, studying Mercury's chemical composition, geology, and magnetic field. The name is a backronym for "Mercury Surface, Space Environment, Geoche ...

'',

STEREO Stereophonic sound, or more commonly stereo, is a method of sound reproduction that recreates a multi-directional, 3-dimensional audible perspective. This is usually achieved by using two independent audio channels through a configuration ...

, and

Van Allen Probes The Van Allen Probes, formerly known as the Radiation Belt Storm Probes (RBSP), were two robotic spacecraft that were used to study the Van Allen radiation belts that surround Earth. NASA conducted the Van Allen Probes mission as part of the L ...

. At one point,

JPL The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, United States. Founded in the 1930s by Caltech researchers, JPL is owned by NASA an ...

was working on including a Scalar Helium Magnetometer on ''Juno'', in addition to the FGM and ASC suite.

Results and papers

In 2017, a paper called ''The analysis of initial Juno magnetometer data using a sparse magnetic field representation'' included analysis of data from the Juno magnetometer which passed 10 times closer than previous probes. The nature of Jupiter's magnetic field was examined, combining the latest results from MAG with a mathematical model called VIP4 spherical harmonic model for the magnetic field of Jupiter.

References

External links

NASA News - NASA's ''Juno'' Peers Inside a Giant - June 29, 2016
{{Satellite and spacecraft instruments Spacecraft instruments Juno (spacecraft) Goddard Space Flight Center Magnetometers

Results and papers

See also

References

External links