Unprecedented 8 satellite view of magnetospheric substorm details and reconnection

Energy tracked from solar wind to Earth

In July 2012, scientists took advantage of a rare eight satellite conjunction across the magnetotail to gain more details of the substorm process.  Below is a depiction of of the satellites involved:

Credit:
NASA/SVS

The initial magnetic reconnection happened very quickly, in a region a couple hundred miles across.  Then, the energy was converted and moved the distance between the Moon and Earth, changing forms along the way.  The final destination was to light up the Aurora at high latitudes.

“One of the unique features of our research field is that microscopic things can sometimes run the whole show,” says David Sibeck, the project scientist for ARTEMIS and THEMIS at NASA’s Goddard Space Flight Center in Greenbelt, Md. “The tiniest causes may have global consequences."

Indeed, small events that happen for a millisecond can drive energy flows lasting up to 30 minutes and cover an area 10 times larger than Earth.

To cover such a vast region, multiple spacecraft are needed, situated at different points throughout the magnetosphere, the protective bubble created by the Earth's magnetic field within the flow of the solar wind.

Have a look at the video to get an idea of the scale we're talking about:

While much of these details have been known and modeled for some time, this is the first multi-scale in-situ measurement, and paid off with some new information about the process.

The energy that this represents is equivalent to a 7.1 magnitude earthquake.  For more details, check out the paper that was produced from the mission results:

Electromagnetic Energy Conversion at Reconnection Fronts
V. Angelopoulos, A. Runov, X.-Z. Zhou, D. L. Turner, S. A. Kiehas, S.-S. Li, and I. Shinohara
Science 27 September 2013: 341 (6153), 1478-1482. [DOI:10.1126/science.1236992]

Abstract
Earth’s magnetotail contains magnetic energy derived from the kinetic energy of the solar wind. Conversion of that energy back to particle energy ultimately powers Earth’s auroras, heats the magnetospheric plasma, and energizes the Van Allen radiation belts. Where and how such electromagnetic energy conversion occurs has been unclear. Using a conjunction between eight spacecraft, we show that this conversion takes place within fronts of recently reconnected magnetic flux, predominantly at 1- to 10-electron inertial length scale, intense electrical current sheets (tens to hundreds of nanoamperes per square meter). Launched continually during intervals of geomagnetic activity, these reconnection outflow flux fronts convert ~10 to 100 gigawatts per square Earth radius of power, consistent with local magnetic flux transport, and a few times 10¹⁵ joules of magnetic energy, consistent with global magnetotail flux reduction.


Late next year, NASA is scheduled to launch the Magnetospheric Multiscale (MMS) mission which will add one more important elelment of the reconnection process - getting a simultaneous measurement of the front side reconnection that preceeds the process shown above.

More information can be found at this NASA page:  Several NASA Spacecraft Track Energy Through Space

Red Sprites

Jason Ahrns, University of Alaska Fairbanks

I like to cover ongoing mysteries in science, and the topic of Sprites is a good one!  Although they were reported in scientific literature as far back as 1886, it wasn't until 1925 that the theoretical underpinnings were discussed.  Experimental proof didn't come for almost 7 decades!

This recent photo was taken by Jason Ahrns of the University of Alaska Fairbanks who was working with an airborne team of researchers from NCAR, using a 'normal' dSLR camera with an image intensifier and settings of f/1.8, ISO 6400, 3/4 second exposure.  They use more sophisticated equipment for the actual research, but bring their personal cameras along to get shots like this which are nicer to look at!

So, what are they?

Sprites are a form of electrical discharge in the upper atmosphere, called the "mesosphere" in the range of 50 to 90 km above Earth.  They are not lightning, but are related to lightning strikes.  As I said in the intro, they are a mystery and we have just begun to get a rough idea about them.  Here's a bullet list of what we do know so far:

•    they are a cold plasma phenomenon
•    they were named after "air spirits", for their rare sightings
•    they are red-orange at the tops, and bluish at their bottoms
•    they tend to appear in clusters of at least 2
•    they can be preceded by an orange halo above
•    they last for just milliseconds
•    they can be produced by both positive and negative (cloud to ground) lightning strikes, but are most often produced by the more rare positive strikes
•    positive lightning produces 7 to 10 times more halos than negative
•    every lightning strike 'tries' to create them
•    initial estimates of their energy were low by a factor of 50
•    they produce VLF & ELF radio waves
•    they consist of balls of ionization that move downward at ~10% of the speed of light, followed by upward moving balls
•    they were theoretically anticipated by C.T.E. Wilson, Cavendish Laboratory, in 1925
•    they were first captured in images by J.R. Winckler,  University of Minnesota in 1989

If you're interested in using Sprites for classroom material, I recommend this publication: THE DISCOVERY OF RED SPRITES AS AN OPPORTUNITY FOR INFORMAL SCIENCE EDUCATION


References (including above):
http://www.spaceweather.com/
http://musubk.blogspot.com/
http://www.scienceblog.com/community/older/2002/B/20026035.html
http://onlinelibrary.wiley.com/doi/10.1029/2004GL021943/abstract
http://www.nobelprize.org/nobel_prizes/physics/laureates/1927/wilson-bio.html
http://en.wikipedia.org/wiki/Sprite_%28lightning%29


UPDATE: August 18, 2013

Some of the comments from a G+ version of this story

UPDATE: Sept 17, 2013

A new video from NASA talks about their Firestation experiment aboard the ISS, which has started operations recently.

In recent decades researchers have discovered some strange things happening in the cloud tops.  High above ordinary lightning, exotic forms known as red sprites and blue elves shoot toward the heavens, cold cousins to the fiery bolts below. In some places jets of antimatter fly upwards, triggering the detectors on NASA's orbiting high-energy observatories.  And as often as 500 times a day, Earth briefly mimics a supernova, producing a powerful blast of gamma-rays known as a Terrestrial Gamma-ray Flash or TGF.

No know knows exactly how these phenomena are related either to each other or to the lightning down below. 

A new experiment called "Firestation" onboard the ISS aims to find out.  Firestation is a package of sensors designed to explore the links between TGFs, ordinary lightning, and sprites.

  

Something up there is accelerating low-energy particles of air to nearly the speed of light, producing gamma-radiation and, sometimes, a cascade of antimatter.  Rowland wants to find out what that strange, unknown "something" is.  Firestation is poised to crack the mystery. 

The full story can be read here: ISS "Firestation" to Explore the Tops of Thunderstorms

Stay tuned for the latest findings!