 |
NASA art rendering of the systems affected
by space weather: aircraft, satellites, astronauts,
and the earth
Source: NASA here gives "fun facts" about the sun |
Let me preface this with a disclaimer: I took a graduate level course in "Electricity and Magnetism" from one of the most fearsome texts ever inflicted on a student, the infamous "Jackson's E and M." It's still used to this day, and everyone that I've met has agreed with me on the difficulty.***See footnote! I not only took it once (in the physics department at the University of Colorado) but again (in the physics department at Caltech) where I didn't understand it any better than the first time around. I blame at least part of my difficulties on faculty who didn't tell me that a course in complex variables was a prerequisite--I'd never had it, and my knowledge of complex variables was limited to the square root of -1!..... Ah, it feels good to make that confession after a mere 45+ years! Hopefully this deficiency won't show up in this post!
Imagine being a telegraph operator and getting shocked by your equipment, or getting up because it was light out only to find out that it was still the middle of the night, or seeing aurorae in the Caribbean! These are some of the effects of the so-called "Carrington Event," a powerful geomagnetic storm in the earth's magnetosphere caused by a massive solar flare and a coronal mass ejection (CME). This was the largest on record, but there have been others. The scientist, Richard Carrington connected the earth's disturbance to the solar flares and is considered the father of "space weather."
A huge solar flare in 1989 shut down Hydro-Quebec, the power grid servicing all of Quebec (and if you've been in Quebec in the winter you can imagine the consequences of such a shutdown). The storm caused tripped five lines from the James Bay facility, causing a loss of over 9,000 MW during a time when the integrated power system (that included Chrchill Falls and Mania-Outardes) was demanding 21,000 MW. The system couldn't withstand that loss and collapsed within seconds. It took 9 hours to restore service and even then 17% of Quebec customers were without electricity. Restoration occurred on a Monday morning when there is typically a high demand on the system, exacerbated by a high demand in heating after 9 hours without power. Another storm in August 1989 caused a halt to trading on Toronto's stock market. Fears today are that similar storms could cause severe damage to modern "smart power grids," perhaps knocking out power for months over areas of hundreds to thousands of miles wide. Financial services, clean water supplies, and even medical care could be crippled by such an event.
In addition to disturbances in the earth's magnetic field, some effects of space weather are high radiation levels, auroras, power outages, radio blackouts, satellite damage and space radiation hazard to astronaut health. In the April 30 Eos, Transactions of the American Geophysical Union, Madhuilika Guhathakurta at NASA headquarters updates NASA space weather research. NASA needs to know the "weather" everywhere in the solar system because there are satellites currently out to the far outer reaches, and it's only a matter of time before astronauts are there as well.
Only a year ago, an intense event occurred, covered on my March 7, 2012 post (Apologies to the reader, but for some reason Blogger is not doing links properly these days). Earlier ones that I have posted including the "Newt Gingrich headliner" of November 14, 2010 that got a lot of hits when I posted it! There is a nice movie on that post. Also, see January 21, 2012, for January 23, 2012, and March 7, 2012. The last one lasted two weeks during which an "angry-looking active region rotated across the solar disk and fired off more than 50 flares, 3 of which were X-class flares, the most powerful type of flare." Before it died, it had hit every spacecraft and planet in the solar system at least once with either a CME or a burst of radiation. The Eos article reports a private communication that this massive activity caused reboots and data outages on as many as 15 NASA spacecraft.
The Eos article is entitled "Interplanetary Space Weather: A New Paradigm." The "new paradigm" is that in contrast to the 'older days' when the focus was on forecasting space weather in the vicinity of the earth, it can now be forecast throughout the solar system, and it was this capability that allowed some protection for spacecraft during the 2012 outburst. NASA has a "heliophysics" fleet of spacecraft, and now has been joined by the Japanese Aerospace Elploration Agency, the European Space Agency and NOAA. Using techniques akin to those used for hurricane forecasting tracks, massive supercomputers at NASA Goddard combine satellite and ground-based data to predict when storms will hit the planets and the NASA spacecraft. E-mails are sent to alert mission scientists when a bout of space weather is about to hit them.
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Two types of magnetic field lines, closed
lines (closed loops, A) and open lines
(the unipolar magnetic field B)
This image is from the Wiki article here.
It is actually for the sun, but imagine that
A is centered over a magnetic
center in the crust of Mars, as is B
but for B the solar wind is sweeping
the lines far out into space. |
One of the more interesting and speculative comments in the Eos article relates to the difference in solar wind interactions with Mars and earth. Citing an article by Brain*, Guhathakurta notes that the magnetic field of Mars is much more complicated than that of the earth. Strong crustal magnetic fields around the planet interact directly with the solar wind. The crustal fields are strongest in the old, heavily cratered, southern hemisphere, except in the large impact basins, such as Hellas and Argyre, which have basically no fields. Crustal fields can be detected as far as 1000 km above the surface, which has implications for the Mars-solar wind interaction. (Added to these effects is the rotation of Mars that changes the orientation of the crustal fields with respect to the solar winds over time.)
The existence of crustal sources of magnetism on Mars means that the magnetic fields are very complicated. Brain describes thee different topologies that the field lines can take on: ones with both "ends" in the interplanetary magnetic field (IMF), closed field lines connected at both ends to Mars (the so-called crustal field lines), unconnected field lines connected at both ends to the IMF, and ones that are open and connect Mars to the IMF. Changes in topology amongst these lines by reconnecting or merging allow the solar wind plasma to be trapped in so-called "magnetic field umbrellas". This leads to a possible answer to a long-standing question: Why doesn't Mars have an atmosphere? We know that Mars once had an atmosphere thick enough to allow liquid water to exist on the surface, yet now it's atmosphere is only a few millibars, a few thousandths of that of the earth. Is it possible that magnetic umbrellas were involved? Could solar wind buffeting the umbrellas cause the magnetic field to pinch off parcels of air trapped in the umbrellas and propel air-filled magnetic bubbles into space?
In 1992 Janet Luhmann and colleagues noted, from Pioneer Venus observations that the atmosphere of Venus was being stripped by the solar wind. They predicted that a substantial loss would have occurred in Martian history. Bruce Jakosky used the ratio of 38Ar/36Ar in the atmosphere and in martian meteorites, and noted that it was some 30% greater than that of the Earth and loss to space was the only process that could produce this type of enrichment in a noble gas. These studies, along with those of other isotopes, suggest that 50-50% of the atmosphere has been lost over time. These studies, amongst others, lead to NASA's MAVEN mission to Mars, set to launch in about 6 months. One goal of MAVEN is to relate the upper atmosphere/solar-wind interactions to the climate and atmospheric history to unravel the history of the surface and past or present habitability by microbes.
Wow...sure makes me wish that I'd done better in that E and M course!
*Brain, D.A., Mars Global Surveyor Measurements of the Martian Solar Wind Interaction, Space Science Reviews, 126, 77-112, 2006.
***See the hilarious comments about this book
here (second edition, the
red book) and
here (third edition, the
blue book)! We true veterans have the
green book, 1st edition!
