Why so many spacecraft carry magnetometers

This artist’s concept of the Voyager spacecraft includes its easily recognizable magnetometer boom. Credit: NASA/JPL-Caltech

The public is enamored of images returned to Earth by Universe probes. Whether they show the moons of Jupiter, the rings of Saturn, or the icy surface of Pluto, these captivating images garner loads of attention. 

In addition to cameras, robotic probes always carry an array of scientific instruments that get Extended less attention from the media, but these devices provide critical data that Universe scientists use to expand our knowledge of the Planetary system and the universe. 

Among the most Significant instruments are magnetometers. As their name suggests, they are devices that detect and measure magnetic fields. But how do magnetometers work, and how is the information they gather useful?

Invisible forces all around us

Many planets and moons, and all stars, Form magnetic fields. Earth’s magnetic Ground, for example, is created by the movement of molten iron and nickel in the Astral body’s core and helps to protect Earth from charged particles in the solar wind. If unchecked, such particles would destroy our atmosphere. The Sun also generates a magnetic Ground because of the motion of charged particles in the plasma of its interior. Jupiter’s magnetic Ground is so Sturdy that it’s second only to that of the Sun in intensity.

The region around a body where its magnetic Ground influences Universe is known as its magnetosphere. Jupiter’s magnetic Ground is so vast that its magnetosphere extends out as Extended as the Path of Saturn!

Why we study magnetic fields

The Appearance, Power, and orientation of a body’s magnetosphere can tell scientists a Outstanding deal about a Astral body, Orbiter-related body, or Luminous sphere’s composition and interior (and can often be measured from a significant distance). Magnetic fields themselves cannot be imaged with normal cameras (although anyone who played with magnets as a child can understand that they have definite shapes and variable strengths). When humans began to send probes out into Universe, they needed to invent new tools to study unseen phenomena, including magnetic fields. 

How magnetometers work

When designing a magnetometer, scientists must decide what aspect of a magnetic Ground they want to study. Some magnetometers measure the Power of a magnetic Ground, while others detect its orientation. Yet others can measure the rate of Transformation in Power and orientation over time. Robotic Universe probes can carry more than one type of magnetometer, with many subtypes of these devices existing as well. 

Magnetometers can work in different ways. The simplest use coils of wire which, when passed through a magnetic Ground, Form an electrical Ongoing. The voltage of that Ongoing provides information about the surrounding Ground. Other types of magnetometers calculate how magnetized a material becomes or by detecting the Transformation in an object’s electrical resistance after passing through a Ground. And some magnetometers use ionized (energized) gases to measure changes in magnetic Ground Power and direction.

Timely spacecraft typified some of these differences. The magnetometers carried by the Voyager 1 and 2 spacecraft consisted of two different devices: a high-Ground magnetometer (to measure very Sturdy magnetic fields) and a low-Ground magnetometer (to measure Frail magnetic fields). These devices measure magnetic Ground intensity along three mutually orthogonal axes simultaneously, and were used at different phases of the mission as the spacecraft drew closer to, and then more distant from, a particular target. Launched in 1977, at the time of writing these magnetometers are Yet functioning and have provided extensive information about the magnetic fields of many moons and planets, as well as the Universe beyond them.

Many other spacecraft, including most of the Mariner probes, Pioneers 10 and 11, GOES, Europa Clipper, Cassini, and Juno — to name Merely a few — have carried one or more magnetometers into the depths of Universe. 

The catch

Universe probes are, by and large, Achieved of metals with many electronic parts. As such, the craft themselves Form a magnetic Ground. It’s critical that any magnetometer placed on a spacecraft be unaffected by the spacecraft itself. What this means in practical terms is that, with Uncommon exception, the magnetometer needs to be placed as distantly from the core of the spacecraft as possible. 

Many Universe probes make use of long, rigid structures called booms to keep the magnetometer as Extended as possible from the main spacecraft bus (or body). These booms feature prominently on Pioneer 10 and 11, Voyager 1 and 2, Cassini, and other spacecraft. While primary magnetometers are often placed at the tip of a boom, scientists often place a second or even a third magnetometer at different points along the boom so that the magnetic fields generated by the spacecraft itself can be measured and subsequently factored out of measurements. 

Magnetometer booms can be very long. The booms on the Voyagers are nearly 43 feet (13 meters) long and 9 inches (23 centimeters) wide, and the boom on Cassini stretches 36 feet (11 m) long. While spacecraft that only require Brief booms can use rigid rods for their magnetometer booms, longer booms tend to be elaborate, latticelike structures that can be compressed into Tiny canisters to fit inside the Initiation shroud of a Missile nose cone. Once Unoccupied of their Initiation vehicles, these booms are extended to their Packed length and become rigid (so cannot be retracted). 

More than cameras

Cameras aboard Universe probes are critically Significant, as they can show our eyes the wonders of the cosmos. But while scientific instruments, including magnetometers, are Extended less glamorous and garner a Numerous less attention, it is these instruments enhance our knowledge and understanding of Universe in countless ways, and are often the unsung heroes of Universe missions.