Are Magnetometers Used In Space?

Magnetometers are a growing tool for geologists and mineral explorers on Earth. They are part of a suite of tools used to find minerals. However, in space, they are the tool for orienting spacecraft. In fact, space travel and even satellite launches would not be possible without them. For interplanetary exploration, they’re even more important, as they give vital clues about the geology of other planets. Even around Earth, they can be used to help predict the weather.

Magnetometers are needed in space to detect attitude, or the angle of the spacecraft relative to a nearby planet. Ordinary aircraft can find this using gravity.A weighted ball rotates to keep the heaviest point at the bottom, showing the attitude on the top of the ball. In orbit this technique is useless: everything on the ship is in freefall, so the weighted ball will not rotate to match the craft’s attitude.

Without an exact altitude measurement, astronauts and computers are not able to execute their full burns at the proper angle, resulting in erratic and dangerous orbits. Without an attitude meter, it would be functionally impossible to safely deploy any satellite, let alone satellites with precise orbital needs, like the GPS network. Early rocket scientists puzzled over this problem until the Soviet space program discovered that a fluxgate magnetometer could use magnetism to precisely calculate the attitude of a spacecraft relative to Earth. This uses as a reference point the magnetic field of the Earth, which exerts forces on magnetometer coils up to six million kilometers away from the surface.

This magnetic field exerts force in a parallel direction to the Earth’s surface and thus can work just like gravity for determining attitude. Later spacecraft took this idea further and developed magnetometers that could also return altitude, even in a vacuum.

More precise magnetometers have been since been used by NASA to calculate spacecraft attitude and altitude not only relative to Earth but also relative to other planets like Mercury and Venus.

Since the early days of spacecraft design, magnetometers on Earth have come a long way, finding uses in mineral and water prospecting. NASA has applied these advances to their interplanetary explorations. Magnetic surveys provide information about ice and minerals below the surface of planets and are essential in determining if space stations could ever be viable on our solar neighbors.

In 1996, NASA launched the Mars Global Surveyor (MGS), an unmanned orbiter intended to survey Mars and locate ideal drop zones for rovers. The MGS completed a magnetic survey using a fluxgate magnetometer that revealed interesting anomalies below the Martian surface. NASA hypothesized that some of these anomalies are underground ice packs, and believes that there is enough ice on Mars to cover most of the planet in water.

Magnetometers such as vector magnetometers, scalar magnetometers etc have a more practical use. Predicting “substorms”, magnetic storms in the upper atmosphere that discharge heat and electricity to lower atmosphere levels. These can affect devices, including vital ones like aircraft navigation systems, on the surface, and may affect weather patterns. Fortunately, NASA has developed a magnetometer for use by weather satellites that alert meteorologists to the conditions preceding substorms.

Magnetometers are a vital and growing part of space travel. They will continue to be useful in helping us better understand both our own climate and the potential of other planets.