Once upon a time, Mars was an expansive, lush planet filled with canyons and lakes. But over time it cooled, its magnetic field dissipated, and streams of ionizing radiation began stripping its atmosphere away. Today it’s an inhospitable desert.
MGS has observed many different kinds of PADs across many regions, which has enabled researchers to study their topologies.
Earth’s magnetosphere
The magnetosphere, Earth’s protective magnetic field, serves to shield it from solar winds and cosmic rays that could otherwise harm it. Extending several tens of thousands of kilometers into space, its extended reach shields both surface-based satellites as well as orbiting satellites from these charged particles while shielding its upper atmosphere – including its ozone layer – from harmful ultraviolet radiation. Created through interaction between solar magnetic fields and rotational movement of planets like Mars; unlike its counterparts Mars does not possess an overarching global magnetic field; rather patches remain buried deep beneath its crust that are remnants from earlier days of its history – remnants from early days when its magnetism existed buried under its crust remnants from early days when life existed on planet.
Mars’ ionosphere structure depends on the strength and orientation of its crustal magnetic fields. A region with lower outward flux for oxygen-containing ions forms above strong crustal fields on Mars’ day side (closer to the Sun) while it gradually dissipates over night side at higher altitudes – this region can be identified using MAVEN spacecraft data.
MAVEN has measured that Mars’ crustal magnetic fields have been evolving over time. A planet’s strength and polarity depends on where its spin axis points relative to the Sun and any angle formed between this vector and radial velocity vector – this direction being known as its magnetosphere’s inclination angle.
An intense magnetic field on Earth can trap atmospheric ions, protecting them from being stripped away by the Sun. But weak magnetic fields – like what exists after Mars’ dynamo shut down – may actually deplete atmospheres faster than without one at all, according to research conducted by Sakata et al.
The team utilized magnetohydrodynamic simulations to understand how an inclined magnetic field impacts its behavior on a planet like Mars, where its dynamo has not been active since dynamo stop spinning, which have revealed that even weak fields such as Mars’ non-active one can send atmospheric ions out into space up to 100 times faster than without such magnetic fields present.
Earth’s dynamo
The Earth’s magnetic field, created by dynamo effect in its rotating iron core, extends far into space. This field protects our atmosphere from being blown into space by solar wind (stream of charged particles) as well as reduce radiation that would otherwise threaten life on Earth. The dynamo mechanism is powered by convective motion of electrically conducting liquid metal within its core; faster rotation speed and higher temperature enhance its effectiveness.
A dynamo’s magnetic field induces electric currents in its outer core and creates a secondary magnetic field, which attracts electrons from outside the core and forces them into loops that conduct electricity. Together these magnetic fields interact to produce electromagnetic waves that form the planet’s magnetosphere; its magnetic field also forms a “magnetotail”, an area surrounding Earth that has been altered by its own magnetic field.
Scientists speculate that Earth and Mars both experienced magnetic fields generated through similar processes during their early lives, however this dynamo eventually stopped working, possibly coinciding with climate change as early environments transformed to their current inhospitable state.
In 2008, an MIT-led team led by Weiss discovered evidence of magnetic traces in rock chunks formed when planetesimals collided 4.5 billion years ago, suggesting that planets don’t require large cooling cores in order to sustain dynamos; planetesimals might instead help provide this source of power.
The InSight probe has conducted detailed magnetic field analyses of Mars, which boasts crustal magnetic fields 30 times stronger than those on Earth. These maps illustrate that its crustal magnetic fields were once active but shut down over 4 billion years ago – coinciding with its thick early atmosphere dissipating and the planet shifting towards an icy cold environment.
Mars’ dynamo
Planetary magnetic fields play an essential role in protecting atmospheres from solar wind, which speeds the loss of water molecules into space, as well as deflecting harmful cosmic rays that could cause life forms harm and accelerate erosion on the surface. But on Mars creating such an infrastructure would require immense strength. Even using its moon Phobos may prove insufficient.
Magnetospheres would reduce the amount of solar wind reaching its surface and affecting climate. They’d also provide some protection from atomic particles released by expanding and cooling Sun. According to their model, creating such a magnetic shield on Mars should be as straightforward as placing a huge magnet at L1 Lagrange point between Mars and Sun; at least 2 Tesla dipole magnets should do the trick without interfering with orbits or disrupting their paths.
The study uses new data from MAVEN satellite, currently exploring Mars. It measures magnetic fields at the ionosphere’s boundary created by plasma flowing from Mars’ surface into space, measuring magnetic fields there as well. Results reveal that regions with stronger crustal magnetic fields tend to have denser ionosphere layers than those with weaker ones.
These discoveries hold important implications for understanding why and how a Martian dynamo ended. Most discussions thus far have assumed that ancient Martian fields were dipolar, while MAVEN observations indicate otherwise. Furthermore, these findings shed light on processes responsible for magnetizing Mars’ crust as well as timing and characteristics of past dynamo activity on this world.
Dynamos require two components in order to generate magnetic fields: a liquid core and the process known as compositionally driven convection. When launched in 2021, InSight will assess whether Mars’ core is liquid and has properties suitable for compositionally driven convection; additionally it will look for evidence of magnetospheres around Mars that would make exploration simpler.
Mars’ magnetic field
Mars’ magnetic field plays an essential role in maintaining Earth-like conditions on its surface while also shielding it from harmful cosmic radiation. It acts as a dynamic and complex barrier against solar winds – supersonic flows of magnetized plasma from the Sun – due to interaction with an ionosphere layer with weakly ionized gas known as an ionosphere and strong crustal fields rotating with Mars that affect how solar wind drapes around this ionosphere and can even produce north or southward twists of tail. Spacecraft measurements have demonstrated how these fields influence solar wind drape around an ionosphere layer; spacecraft measurements have confirmed their influence, with north or southward twists of tail being produced due to interactions between this complex field interaction of interaction between these fields and how much influence there is created when it comes to protecting against cosmic radiation exposure from cosmic sources from cosmic sources coming from cosmic sources outside.
Satellite instruments and ground-based sensors have collected magnetic field data on Mars to gain more of a deep understanding of its magnetic field and evolution, yet there remain several outstanding questions concerning its distribution, its origins and history – these questions motivate further study in areas listed in Table 1.
Mars’ hybrid magnetosphere results from interactions between its induced and intrinsic magnetic fields, with one feeding into the other. While its induced component resembles Venus’ global dipole field-driven magnetosphere, its intrinsic component more closely resembles Earth due to the contributions from draped fields cancelling each other out to near zero Bx/|B| (Xu et al 2020). By contrast, when studying open fields alone we observe dipole-like tail lobe configurations that suggest its role in mars’ interaction with solar wind energy.
Recent work utilizing magnetic topology has successfully isolated both induced and intrinsic components of Mars’ hybrid magnetosphere. Results demonstrate that draped fields remain induced/Venus-like while open fields reveal dipole-like intrinsic fields reminiscent of dipole dipole interactions seen on Earth. These findings support the notion that Mars’ magnetosphere and solar wind interactions resemble those on Earth more closely than previously believed. Though its causes remain enigmatic, such intrinsic fields could help explain why Mars has more of a twist to its tail during ICME encounters than its counterparts on other planets.