Magnetic Fields & Space Travel
- Sylvia Rose
- Mar 21
- 4 min read
Magnetism affects the way spaceships and astronauts travel through space. The invisible forces generated by magnetic fields influence navigation and propulsion, and protect from cosmic radiation.
Magnetism arises from the motion of electric charges. Electricity is created by movement of negatively charged particles, or electrons, which flow through a conductor such as silicon or nickel to create electric current.
The planet generates a magnetic field, the magnetosphere, from the molten metals of its outer core. Iron and nickel, excellent conductors, are in constant motion, driven by convection currents and Earth's rotation.
Their movement generates electric currents. These produce the magnetic field, a process known as the geodynamo. It forms a protective shield against solar winds and cosmic radiation, and is constantly in flux.
Earth's magnetic field is weakening, with a global average decrease of about 9% over the past 200 years. Some areas have a more rapid decline.
This can indicate a shift towards a pole reversal, a phenomenon which hasn't happened in 780,000 years. It's a gradual process over thousands of years. When the poles flip the field starts to get stronger again.
Space abounds with charged particles primarily from solar winds, at a density up to 1.5 million particles per cubic centimeter. The particles can sabotage spacecraft systems and operational safety.
The magnetosphere deflects charged particles. It prevents them from reaching the Earth's atmosphere to wreak havoc on electrical systems and communication networks.
Earth's magnetosphere extends into space about 65,000 kilometers (40,000 miles) on the sunward side. It trails out much further, forming a "magnetotail" able to extend past the moon on the night side.
Magnetism strongly affects the trajectory of spacecraft in Earth's orbit. The charged particles in the solar wind interact with the magnetosphere, creating a region of disturbed magnetic fields known as the magnetotail.
As spacecraft pass through this region, changes in the magnetic field can affect navigation and communication systems. The magnetotail can trigger electric currents in spacecraft.
Where a compass is used on Earth, spacecraft use more advanced technology like magnetometers. These measure strength and direction of magnetic fields to pinpoint their location relative to celestial bodies.
On Mars, incoming spacecraft analyze the Martian magnetic field to ensure they're properly positioned for landing. Magnetic data is highly relevant in journeys covering millions of miles.
Mars Rovers for instance travel over over 300 million miles to reach the Red Planet. Both the US and China have been able to land functioning rover craft on Mars.
Magnetic fields can move spacecraft using magnetoplasmadynamics or magnetic sailing. By creating a magnetic field to interact with solar wind, spacecraft generate propulsion force. It reduces fuel needs, increasing endurance and range.
Plasma is the fourth state of matter, abundant in space. A highly charged and ionized gas, it generates powerful magnetic fields affecting motion of celestial bodies.
Behavior of plasma and its magnetic fields is a subject of much study. It helps understand dynamics of the universe, and formation of structures such as galaxies and galaxy clusters.
Electromagnetic propulsion systems, such as ion thrusters, use magnetic fields to accelerate ions, generating thrust. This method is more efficient than traditional chemical propulsion systems, with vast fuel savings.
NASA's Dawn spacecraft travels to the asteroid belt, using ion propulsion for more than 57,000 hours. Ion propulsion can shorten travel times and reduce energy use, making long-duration missions practical.
Magnetism influences behavior of celestial bodies like stars and planets. Magnetic fields of stars can affect the motion of planets in their orbits, causing them to wobble or oscillate.
Cosmic radiation is a major threat to astronauts on extended missions. At the International Space Station (ISS), astronauts are exposed to 100 to 200 times the radiation dose of Earth.
Magnetic shielding can create a protective bubble around spacecraft. The concept imitates Earth's magnetic field. Superconducting materials or superconductors help create the shield.
When cooled below a certain temperature, superconductors have zero electrical resistance and also expel magnetic fields. This allows the electrons of electricity to flow without energy loss.
Superconductors include titanium, lead and yttrium. Strontium titanate, discovered in the 1960s, is a non-metal superconductor. It's a human-made gem material and diamond simulant known for a high refractive index.
Superconductors are used in applications needing powerful magnetic fields, such as MRI machines, particle accelerators, and maglev trains. They also function in power transmission and electronics.
In space, they're currently used in instruments requiring high sensitivity and efficiency, such as in particle astrophysics detectors, and for powering cryogenic components. R&D continues.
Magnetic fields of planets also affect atmospheric behavior, generating electric currents and winds influencing climate and weather. The magnetic field of Jupiter is the largest in the solar system.
It generates powerful auroras, or northern and southern lights. Different celestial bodies have unique magnetic fields.
Mars has a weak magnetic field, about 1% the strength of Earth's, which increases exposure to solar radiation. It's one of the hazards to overcome in hopes of landing astronauts on the planet.
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