Slashdot Mirror

← Back to Stories (view on slashdot.org)

NASA Proposes a Magnetic Shield To Protect Mars' Atmosphere (phys.org)

Posted by BeauHD on from the science-fiction-to-science-fact dept.

New submitter Baron_Yam writes: Apparently it is no longer necessarily science fiction to consider terraforming the red planet in a human lifetime. NASA scientists have proposed putting a magnetic shield at the Mars L1 Lagrange Point, diverting sufficient solar wind in hopes that the Martian atmosphere would thicken and heat the planet to the point of melting the ice caps, causing what remains of Martian water to pool on the surface. While not enough of a change to allow walking around without a space suit, this would make human exploration of the planet a much easier task.

22 of 211 comments (clear)

  1. No real information by Anonymous Coward · · Score: 2, Informative

    They don't mention much about how this magical magnetic barrier is going to be generated or powered. They also don't really know how long it will take a habitable atmosphere to form assuming it works at all, or what happens to everything if the shield fails at a later date and what kind of upkeep it would require. It sounds a lot like wishful thinking and hand-waving.

    1. Re:No real information by jandersen · · Score: 5, Interesting

      It sounds a lot like wishful thinking and hand-waving.

      It probably is, at that. In my (limited) experience, phys.org tends to publish stories rich in big, glossy pictures, slightly sensationalising headlines and with a rather too "popular" (read: dumbed down) style. Maybe I'm being unfair, but I don't think their stories tend to qualify as real news, when most of it is a glossy writeup of things I have already seen elsewhere, on general news media like the BBC.

      I think this is a fundamental problem when popularising science news - when you look at the totality of science, and especially the amazing discoveries made in the first half of the 20th century, it really is quite mind-blowing, but unfortunately this does not reflect the day-to-day reality of most science. Which is why most attempts at making science news popular and exciting are doomed to be disappointing.

      As for the actual idea - I think it is well-established that a magnetic shield would be just the thing to protect the atmosphere of a planet (or the passengers of a spacecraft), but the technical challenges are enormous, and the benefits to Mars would probably be slow and rather minor. At this point it is mostly speculation, but of course, all the great things we now take for granted once were little more than dreams and handwaving, so who knows? Perhaps we find a way to produce a magnetic fields big and strong enough that would endure long enough with little maintenance, and perhaps we find a way to replenish Mars' atmostphere quickly enough to make it worth doing.

    2. Re:No real information by Joce640k · · Score: 4, Funny

      They don't mention much about how this magical magnetic barrier is going to be generated or powered.

      If only there was an easy way to make working superconductors in near-zero ambient temperature environments.

      (or even an easy way to read articles from the comfort of home)

      --
      No sig today...
    3. Re: No real information by Anonymous Coward · · Score: 3, Funny

      That's what they told me initally.

      Now I have hairless genitalia.

    4. Re:No real information by rgbatduke · · Score: 2

      So, 1-2 Tesla peak in a device how large? A meter? Ten meters? A kilometer? (what are we going to pay for, in other words) sitting in the middle of nowhere is going to be enough to deflect off-axis charged particles by how much? Bear in mind that Mr. Sun subtends a pretty substantial arc. One such that an entire planetoid object the size of the moon barely obstructs line of sight in a tiny penumbra, sometimes, at 384K kilometers...

      So just how large a region WOULD we have to cover to actually put the entire planet of Mars in its deflection penumbra? Hmmm....

      If we're going to this place, why not do the same thing for Mother Earth -- put a large cloud of stuff at the lagrange point, reduce insolation, fight global warming. Price is no object! Fantasies are free! Besides, what could go wrong?

      rgb

      --
      Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.
    5. Re:No real information by ElizabethGreene · · Score: 2

      L1 is an unstable Lagrange point though, so this contraption would need constant tweaking to stay in the right spot.

      It would be nifty if we could figure out a way to tack into the Solar wind so this didn't require continuous resupply of propellant.

    6. Re:No real information by rgbatduke · · Score: 5, Informative

      Well, that escalated quickly! Howbow I just reply to your first questions, because sunlight blocking isn't related nor makes much sense to me.

      Let's try to make it make sense. The solar wind is driven by light pressure. Particles do not, however, follow strict radii out from the sun. They have transverse velocity components as well as radial ones. Also, they are pushed by photons from all over the face of the sun, which have different impact angles, which constantly change their transverse velocity. To put it another way, the particles driven away from the sun that will eventually hit Mars have a phase space envelope at least as large as the truncated cone formed by the surface of revolution whose boundaries are the circumference of the Sun on one end and the circumference of mars at the other.

      Now consider a satellite (say) 100m in diameter. Suppose you locate it at the Lagrange point so that it is always along the line between the center of the Earth and the center of the Sun. Question: Will it dim the total sunlight received by the Earth?

      Not measurably. The penumbra of this little satellite extends from its dark side to the tip of the extended cone formed by the circumference of the satellite and the circumference of the Sun. Since the Sun is basically 0.5 degrees from the Earth or the Lagrange point either way, the height of this cone is found from tan(0.5 degrees \approx 0.02 rad) \approx 0.02 rad = 100/H, or
      50x100 = 5 km. So the satellite will cast a complete shadow of the sun that starts out 100 m wide right behind the satellite, then shrinks to zero around 5 km (give or take a km, I'm being lazy) . Beyond that you are in the umbra, which basically means that you are in bright sunlight from the annulus of sun surface visible around the satellite. The further out you go, the smaller the ratio of the occluded part to the directly visible part. By the time you reach the earth, the satellite is completely invisible -- the umbra is irrelevantly dimmed relative to no satellite at all, and it "covers" less of the sun's face from any viewpoint on Earth than a medium sized sunspot.

      Now, if somebody were to tell you "hey, we're going to fix global warming by putting a sun shield in geosync orbit to reduce the total insolation of the Earth", your first concern would be to think about the geometry of that penumbral cone with a known cone height of roughly 5 earth radii vs a 0.5 degree Sun. Just how large would it have to be to reduce total insolation by a single whopping percent? The answer is really, really large. Even at only 5 Earth radii, which is not the distance to a Lagrange point. At the Lagrange point, really really REALLY REALLY large.

      Now, is the solar wind deflection by a magnet going to be exactly like this? No, of course not. The magnetic field doesn't have a sharp cutoff -- it drops off roughly like 1/r^3 from the center of the (presumably dipole) magnet. Also, the force acting on the solar wind (charged only) particles depends on their charge and speed, the acceleration depends on their mass as well, and it has the usual nasty cross products in it so that it only really exerts a large force when particles run across the field at right angles. One would LIKE to think that a small deflection far away produced by a magnet large enough to produce a reasonable deflection a REALLY REALLY large distance away from the magnet could create a shadow as large as Mars, but it is by no means clear that this is the case, and just saying "hey, we can make really big magnets" doesn't actually help. I've got really really big magnets in my house -- ones I've pulled out of dead hard drives, that can basically hold a (small) newspaper pinned to your fridge. IF you get them within an appallingly short distance of the fridge. From a meter away, you can't feel any force at all. If you take an old CRT television or computer monitor and wave this really really strong magnet from ten or twenty meters away, it has

      --
      Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.
  2. Let's do it... by Camel+Pilot · · Score: 4, Insightful

    What the hell are we waiting for? Having 4.2 Billions years of evolutionary investment held captive at the bottom of one gravity well is not a good long term strategy.

    1. Re:Let's do it... by Wescotte · · Score: 2

      Cave Johnson would like a word with you.

  3. Re:While were at it by KiloByte · · Score: 2, Informative

    Well, a 22km (72,000 foot for those using medieval units) mountain is not high enough for you? Add water and you'll have snow.

    --
    The creatures outside looked from Alt-Right to Antifa; but already it was impossible to say which was which.
  4. Re:Isn't L1 unstable? by Henning+Rogge · · Score: 2

    You don't place it exactly at L1, you place it slightly out of L1 so the pressure of the solar wind will be countered by a gravity pull towards the Sun.

    Of course you need some "thrusters" to keep the thing at the right place, but this should be easy to do by changing the shape of the magnet field, using the solar wind itself to move the shield around.

    Not easy, but technically possible

  5. Timescale is all wrong by goodmanj · · Score: 5, Insightful

    This is a cool idea, but do the math: if you were able to shut off the reported 0.1 kg/s of atmospheric mass loss, how long does it take to double the atmospheric mass (about 2.5 x 10^16 kg)?

    Related question: does it count as terraforming if the Sun blows up before you finish the job?

  6. Hey by Dunbal · · Score: 2

    I know a kid inventor who can do wonders with stuff from Wal Mart I'm sure he can come up with something.

    --
    Seven puppies were harmed during the making of this post.
  7. Re:Positive feedback by Ihlosi · · Score: 3, Insightful
    Kickstart it by exploding every nuke we have on the poles as well.

    Dropping a few space rocks on Mars might work better and add even more volatiles to the planet.

  8. Actually doesn't sound all that nuts by tomxor · · Score: 2

    Trying to generate a magnetosphere in place is hard, but this is quite a strategic alternative. Nothing is cheap when talking about Mars, but this has to be one of the cheapest long range construction projects with the largest potential change to the planet.

    1. Re:Actually doesn't sound all that nuts by Baron_Yam · · Score: 3, Interesting

      There's a lot of 'Mars stuff' I'm surprised we don't toy with more. Or maybe we are, but it's all in some lab because (so far) that's good enough given our current level of technology and knowledge.

      You'd think, for instance, somewhere someone should be experimenting with the minimum requirements for rendering Martian regolith into non-toxic, fertile ground. Toying around with the power requirements to augment Martian sunlight and temperatures to levels required to support Terran plants or trying to engineer plants that will grow and thrive at Martian insolation levels. Figuring out how to reliably supply the required power.

      Or playing around with in situ production of building materials, automated mining and refining equipment, etc. Maybe we just don't have a firm enough grasp on what the Martian surface is actually like to bother starting with that. Send a robot to make a little red brick igloo, you know?

      I'd certainly be up for a really inhumane experiment - sending a colony of mice in a sealed environment to see multiple generations of mammals under 0.38g. And it might be nice to attempt a small terrarium with some automated environmental systems to see how long we can keep it going. And while we're at that... drop a scale model of an airlock and cycle it until it fails so we can see how bad the dust problem is.

    2. Re:Actually doesn't sound all that nuts by drinkypoo · · Score: 4, Informative

      You'd think, for instance, somewhere someone should be experimenting with the minimum requirements for rendering Martian regolith into non-toxic, fertile ground.

      You would think that, yeah. Indeed, we probably have some sort of simulated martian regolith that can be used for this sort of research.

      Toying around with the power requirements to augment Martian sunlight and temperatures to levels required to support Terran plants or trying to engineer plants that will grow and thrive at Martian insolation levels.

      That sounds quite handy.

      Or playing around with in situ production of building materials, automated mining and refining equipment, etc.

      Yes, it would be handy if you could make bricks, or perhaps concrete.

      I'd certainly be up for a really inhumane experiment

      When can you be ready to go?

      --
      "You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
  9. Re:Positive feedback by Ihlosi · · Score: 4, Insightful
    How do drop "space rocks" on a planet?

    1. Make a list of known space rocks of suitable size and composition.

    2. Sort list by amount of delta-v required to have each candidate impact on Mars.

    3. Pick one of the candidates with the lowest delta-v requirements.

    4. Apply necessary delta-v.

    .. what? We're talking about a plan to create a planet-sized magnetic shield. If we assume we can do that, then moving a few space rocks shouldn't be too hard?

  10. Re:While were at it by gnick · · Score: 2

    No need. Mars already has a mountain 15 miles high (Olympus Mons') you can use for that purpose after the atmosphere comes back.

    For now, maybe. But what about after the rise of the sea levels? Let's call this what it is - Man-made Martian climate change.

    --
    He's getting rather old, but he's a good mouse.
  11. Please NASA by jpellino · · Score: 5, Funny

    stop watching "Thunderbirds" in the break room.

    --
    "Win treats sysadmins better than users. Mac treats users better than sysadmins. Linux treats everyone like sysadmins."
  12. Troubling words from TFA. by fahrbot-bot · · Score: 5, Funny

    Magnetosheath, Magnetopause, Magnetotail

    Carnac the Magnificent: (opens envelope) "Things X-Man Magento doesn't want to see on his annual medical report."

    --
    It must have been something you assimilated. . . .
  13. Re:Positive feedback by PPH · · Score: 2

    1. Make a list of known space rocks of suitable size and composition.

    We tried that. But someone used MongoDB and we couldn't figure out how to query it on a time scale comparable to terraforming.

    --
    Have gnu, will travel.