Spacecraft magnetometer

There are ongoing missions using magnetometers,[example needed] including attempts to define the shape and activity of Saturn's core.

The first spacecraft-borne magnetometer was placed on the Sputnik 3 spacecraft in 1958 and the most detailed magnetic observations of the Earth have been performed by the Magsat[1] and Ørsted satellites.

Many instruments have been used to measure the strength and direction of magnetic field lines around Earth and the Solar System.

Many later magnetometers contain small ring-coils oriented at 90° in two dimensions relative to each other forming a triaxial framework for indicating direction of magnetic field.

[2] In 1959 the Soviet "Luna 1"/Ye1.4 carried a three-component magnetometer that passed the Moon en route to a heliocentric orbit at a distance of 6,400 miles (10,300 km), but the magnetic field could not be accurately assessed.

[2] Eventually the USSR managed a lunar impact with "Luna 2", a three component magnetometer, finding no significant magnetic field in close approach to the surface.

During 1958 and 1959 failure tended to characterize missions carrying magnetometers: 2 instruments were lost on Able IVB alone.

Only Mariner 2 survived launch and as it passed Venus on December 14, 1962 it failed to detect a magnetic field around the planet.

This was in part due to the distance of the spacecraft from the planet, noise within the magnetometer, and a very weak Venusian magnetic field.

The Lunar Prospector-1 uses ring-coil made of these alloys extended away from each other and its spacecraft to look for remnant magnetism in the Moons 'non-magnetic' surface.

Later it was discovered that creating a spherical structure with feedback loops wire transverse to the ring in the sphere could negate this effect.

[10] In September 1979 a Vela satellite collected evidence of a potential nuclear burst over the South Western Indian Ocean.

[11] And currently it is investigating magnetic fields at 10 to 30 Earth radii with the THEMIS satellites[12] THEMIS, which stands for Time History of Events and Macroscale Interactions during Substorms is an array of five satellites which hope to gather more precise history of how magnetic storms arise and dissipate.

The magnetometer was fouled accidentally which caused it to overheat, it worked for a period of time but 52 h into the mission transmission went dead and was not regained.

[14] Ranger 1 and 2 carried a rubidium vapor magnetometer, failed to reach lunar orbit.

[2] This type of magnetometer depends on the variation in helium absorptivity, when excited, polarized infrared light with an applied magnetic field.

[16] Mariner 5 used a similar device For this experiment a low-field helium magnetometer was used to obtain triaxial measurements of interplanetary and Venusian magnetic fields.

Several strategies can be employed, it is easier to rotate a space craft about its axis than to carry the weight of an additional magnetometer.

One of the problems, for example in studying planets with low magnetic fields like Venus, does require more sensitive equipment.

Ironically satellites launched more the 20 years ago still have working magnetometers in places where it would take decades to reach today, at the same time the latest equipment is being used to analyze changes in the Earth here at home.

On Pioneer 6 and Injun 1 the magnetometers were mounted to a bracket external to the space craft and readings were taken as the spacecraft rotated every 120°.

[19] The fluxgate on Explorer 6 was mounted along the spin axis to verify spacecraft tracking magnetic field lines.

The Sun was used to sense the position of the boom mounted device, and triaxial vector measurements could be calculated.

One of the first Dual technique systems was the abbreviated Explorer 10 mission which used a rubidium vapor and biaxial fluxgate magnetometers.

The Overhauser magnetometer is situated at the end of an 8 meter long boom, in order to minimize disturbances from the satellite's electrical systems.

For relatively insensitive work, such as "compasses" (attitude sensing) in Low Earth orbit, this may be sufficient.

The most sensitive magnetometer instruments are mounted on long booms, deployed away from the craft (e.g., the Voyagers, Cassini).

Magnetometer booms for vector instruments must be rigid, to prevent additional flexing motions from appearing in the data.

Some vehicles mount magnetometers on simpler, existing appendages, such as specially-designed solar arrays (e.g., Mars Global Surveyor, Juno, MAVEN).