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Life, Unbounded

Life, Unbounded


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The X Factor: Solar storms and life as we know it

The views expressed are those of the author and are not necessarily those of Scientific American.


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Back in February 2011 the Sun underwent a so-called X class solar flare event, prompting the following Life, Unbounded post. I thought I’d bring it out to air again in light of the solar flare events happening right now, and the potential for some disruption of our Earthly activities. There are also interesting implications for exoplanets…

Aurora seen from Space Shuttle Discovery in 1991 (NASA)

This past week (February 21st, 2011) the Sun underwent an X-class solar flare and subsequent coronal mass ejection event. It was notable for a number of reasons. The Sun is slowly emerging from a minimum of activity – part of its roughly 11 year cycle of magnetic disturbance – and this was the most significant event of the past 4 years where Earth was in the line of fire for millions of tons of protons squirting out into interplanetary space. Flares come in C, M and X classes – only M’s and X’s have the potential to cause significant impact on Earth’s upper atmosphere and geomagnetic system. It was also notable for the serious media attention it received.

In part this is probably due to a big, thorough, and thoroughly scary report that the National Academy of Sciences put together back in 2008. “Severe Space Weather Events – Understanding Societal and Economic Impacts” is actually fascinating reading, but it also pulls no punches. Modern human civilization has built itself an infrastructure that is acutely vulnerable to geomagnetic interference. Yes, satellites can get knocked out by solar storms. Yes, GPS can be disrupted for significant periods (aren’t you glad that worldwide air travel is now utterly reliant on global positioning?). But the real double-whammy comes from the trillion watt electrical currents induced in the Earth’s atmosphere and conductive surface and subsurface structures. We already know what this can do. Knock out eastern Canada’s power grid for 9 hours in 1989. Melt huge electrical transformers in New Jersey. A hundred million dollars of damage in a couple of hours. And that was mild. Back in 1859 the so-called ‘Carrington Event‘ was an upper X-class solar belch that caused large parts of the United States new telegraph system to overload and catch fire. Vivid aurora were seen in the skies as far south as Cuba. Campers thought dawn had come in the Rockies.

The National Academy report soberly estimates that another big X-class event hitting the Earth full on could cause $1-$2 trillion in basic infrastructure damage. Now that’s a deficit [oh simpler times, I wrote that in February 2011, little did I know]. Little wonder that those in communications, power supply, and a host of other industries are watching the Sun very closely. We’ve built a lot of new systems in the past 11 years that have not yet been tested by solar storms.

All of this is close to home, but it may offer some important insight to a seemingly perennial topic in the search for life elsewhere. Much attention is focused on  planets around low mass stars – over 70% of all stars are less than 1/2 the mass of our Sun. Lower stellar mass and smaller radius means that radial velocity and transit planet surveys can reach down to lower mass planets. Greater numbers also up the odds of planet-hosting systems in our immediate galactic neighborhood, far better for detailed study. These stars have extremely long hydrogen-fusing lifetimes, into the trillions of years for an object 1/10th the mass of our Sun. The drawbacks are that planets in the small and narrow habitable zones of such stars are both likely to be slow-rotating, tidally locked worlds, and subject to the excessive crankiness of this stellar class.

Illustration of M-dwarf star (NASA/Walt Feimer)

Energy transport within the lowest mass stars is almost entirely via convection. In other words, low mass stars are bubbling, seething spheres of plasma that more or less turn themselves inside out on a regular basis. Our own Sun by comparison is very static in its deep interior, energy being carried solely by photons bouncing their way up through its bulk. Low-mass stars flare like crazy for at least the first 1-2 billion years of their lives, and potentially much longer. Whether Earth-type planets in close orbits can remain habitable has long been a topic of discussion. At the crudest level it comes down to whether a planet can hold onto its atmosphere in the face of stellar onslaught. It seems that even a modest planetary magnetic field can go a long way to preventing atmospheric erosion.

Our current predicament points to another issue though. It’s awfully hypothetical, but perhaps not as much as it was a few months ago, before Kepler confirmed the planetary richness of our galaxy. Could technological life develop on a world pounded by geomagnetic disturbances? I know, big jump here. Usually I’m discussing how appallingly earth-centric we are about the nature of life, but for once let’s allow some leeway. It seems that figuring out how to exploit the flow of electrons could be severely hampered for anything but the smallest types of apparatus (planet of the iPods?). Radio-wave communication might be an enormous challenge. The radiation environment in low to high orbit could be severe – and even with a planetary magnetic field then atmospheric density variations due to flare energy input would make spacecraft stability an ongoing headache. Humans did pretty well at surviving long, long before voltaic cells – albeit as a more agrarian species. On a planet kept under electromagnetic siege there would be little to be gained by moving technology in an electrical direction. Could there be intelligent and advanced life out there that just doesn’t bother with cell-phones, GPS, or planetary radar because it’s too much hard work?

Caleb A. Scharf About the Author: Caleb Scharf is the director of Columbia University's multidisciplinary Astrobiology Center. He has worked in the fields of observational cosmology, X-ray astronomy, and more recently exoplanetary science. His latest book is 'Gravity's Engines: How Bubble-Blowing Black Holes Rule Galaxies, Stars, and Life in the Cosmos', and he is working on 'The Copernicus Complex' (both from Scientific American / Farrar, Straus and Giroux.) Follow on Twitter @caleb_scharf.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. Eniac 12:34 am 09/4/2011

    Or, in an environment where a simple conductive loop could generate significant power out of seemingly nowhere, maybe they could skip fire and get to the electrical age directly. Perhaps their (non-intelligent) plants would even use electricity, instead of light.

    Link to this

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