Terraforming Mars is one of the great dreams of humanity. Mars has a lot
going for it. Its day is about the same length as Earth's, it has plenty of
frozen water just under its surface, and it likely could be given a
reasonably breathable atmosphere in time. But one of the things it lacks is
a strong magnetic field. So if we want to make Mars a second Earth, we'll
have to give it an artificial one.
The reason magnetic fields are so important is that they shield a planet
from solar wind and ionizing particles. Earth's magnetic field prevents most
high-energy charged particles from reaching the surface. Instead, they are
deflected from Earth, keeping us safe. The magnetic field also prevents
solar winds from stripping Earth's atmosphere over time. Early Mars had a
thick, water-rich atmosphere, but it was gradually depleted without the
protection of a strong magnetic field.
Unfortunately, we can't just recreate Earth's magnetic field on Mars. Our
field is generated by a dynamo effect in Earth's core, where the convection
of iron alloys generates Earth's geomagnetic field. The interior of Mars is
smaller and cooler, and we can't simply "start it up" to create a magnetic
dynamo. But there are a few ways we can create an artificial magnetic field,
as a recent study shows.
Ideas for generating a Martian magnetic field have been proposed before, and
usually involve either ground-based or orbital solenoids that create some
basic level of magnetic protection. In the TV series "The Expanse," you can
see a couple of scenes where you catch a glimpse of them. While this latest
study acknowledges that might work, it proposes an even better solution.
As the study points out, if you want a good planetary magnetic field, what
you really need is a strong flow of charged particles, either within the
planet or around the planet. Since the former isn't a great option for Mars,
the team looks at the latter. It turns out you can create a ring of charged
particles around Mars, thanks to its moon Phobos.
Phobos is the larger of the two Martian moons, and it orbits the planet
quite closely—so closely that it makes a trip around Mars every eight hours.
So the team proposes using Phobos by ionizing particles from its surface,
then accelerating them so they create a plasma torus along the orbit of
Phobos. This would create a magnetic field strong enough to protect a
terraformed Mars.
It's a bold plan, and while it seems achievable, the engineering hurdles
would be significant. But as the authors point out, this is the time for
ideas. Start thinking about the problems we need to solve, and how we can
solve them, so when humanity does reach Mars, we will be ready to put the
best ideas to the test.
Reference:
R.A. Bamford et al, How to create an artificial magnetosphere for Mars, Acta
Astronautica (2021).
DOI: 10.1016/j.actaastro.2021.09.023
Tags:
Space & Astrophysics