May, 2005....J. Dana Hrubes...updated May 31, 2005 , 0900 GMT

During an aurora an Iridium satellite flares as it reflects sun from one of its antennas

May at the Pole - darkness, stars, auroras, satellites

May is the first full month of darkness. At the South Pole Station Space Sciences Laboratory (formerly the South Pole Cusp and Cosray Labs) it is an exciting time of the year. The laboratory is made up of a combination of projects investigating the physics of the Earth's upper atmosphere and the effects of solar-terrestrial interaction. From numerous antennas, magnetometers and other sensors as far as a mile off station, we measure fluctuations in the magnetic field of the earth, electromagnetic waves from extremely low frequency (ELF) through high frequency (HF), cosmic rays from our sun and galactic sources, and cosmic radio noise absorption in the upper atmosphere. These measurements are all influenced by solar events and fluctuations in the solar wind. This time of the year, however, when the sun is below the horizon for six months, we are able to also experience one of visually awesome effects of solar terrestrial interaction, auroras.      aurora with red highlights        red aurora       aurora with full moon       rays      aurora over the new station    aurora over the geodesic dome      large aurora      

The combination of the magnetic field of the Earth and the flux of charged solar particles create what is called that magnetosphere, a complex region surrounding the earth where extremely large electrical currents are generated and transferred, ultimately to the ionosphere, resulting in the creation of aurora. It is primarily electrons with very high energies that strike and excite air molecules and atoms between about 50 and 250 miles above the Earth's surface. Once these excited molecules and atoms relax back to their normal state they emit light energy or photons, each at specific wavelengths or colors, much like the excited neon atoms in a neon bulb emit a specific wavelength of orange light.

When particularly strong solar events occur that eject an increased flux of charged particles in a direction that intersects the Earth, like the coronal mass ejection (CME) that occurred on May 13th, we can expect markedly increased disturbances in the magnetosphere and the ionosphere resulting in exceptionally beautiful auroral displays. The speed of the charged particles varies, depending on the strength of the event, but it usually takes 1 to 3 days for the bulk of the particles to reach the earth. In this recent case, the bulk of the particles from the CME on the 13th reached to Earth at about 0300 GMT on May 15th resulting in bright auroral displays not only at the South Pole and Antarctica, but in regions of the northern hemisphere as far south as Arizona.      circular aurora           huge aurora with the southern cross        aurora backlighting the SETI telescope site          telescope       distant aurora         aurora over the dome and the new station

Auroras can be observed almost every day during the long dark winter at the geographic South Pole. On a typical day in the Cusp Laboratory, on the first floor of skylab, one can hear and “see” auroras as they occur. A speaker is connected to the output of the VLF radio receiver and since most of the VLF band is within the audio band you can hear VLF events such as auroral hiss, which sounds like bacon frying under a microphone. Auroral hiss frequently occurs 10 or more minutes before an aurora is visible. Once I hear that sound, I glance over to my charts, look at the real time magnetic field and photometer plots and frequently find that an aurora is taking shape. I then run out the back door of skylab for visual confirmation and if it is a good aurora I will make an all-station announcement. Another sign of geomagnetic disturbance, and frequently, auroral displays, are rapid oscillations of the Earth's magnetic field. Other audible electromagnetic VLF wave events are named “whistlers”, “chorus”, “auroral kilometric radiation (AKR)” and “saucers”.      strip chart showing onset of the CME        event with VLF radio emission prior to magnetic field oscillations and auroral display    

The Cusp Laboratory at the South Pole was named after the geomagnetic cusp, a "window" over the polar regions where charged particles from the solar wind are able to enter the Earth's upper atmosphere.  This laboratory, currently in the skylab building, will be moved up to the new station in November, 2005.      the space sciences "cusp" laboratory       

The upper atmosphere is studied in order to gain a better understanding of the effects of the sun on our planet and its magnetic field. Data is collected to aid in modeling this complex system and enable us to predict when severe events and geomagnetic storms will occur. Major disturbances in our upper atmosphere and magnetosphere can effect us here on earth by disrupting and damaging satellites, causing power surges and damage to power distribution networks in the higher latitudes, generating electrical potentials, currents and subsequent damage in long pipelines and cable systems as well as many other things that affect life on this planet.

The South Pole experienced numerous Iridium satellite flares this month (see April, 2005 for more information on Iridium flares).         iridium flare viewed near the Atmospheric Research Observatory       iridium flare with aurora  

During a two day flare period in mid May (we get flares every 9.16 minutes), we saw rare double flares apparently caused by the reflection of the sun from one of the satellite's solar panels, about 15 seconds after the main flare or reflection from one of the antennas.         double flare (photo by K. Siman)          double flare (photo by R. Schwarz)   

Iridium satellite flare from the reflection of the sun from one of its antennas backlit with a mild aurora

During a 3 day period from May 29 through May 31 we again had both "standard" Iridium flares caused by the sun's reflection from one of the satellite antennas and flares caused by reflection from a solar panel. Each flare was occurring every nine minutes, but this time the antenna reflections were occurring on satellites from one of the six orbital planes containing 11 satellites and the solar panel flares were occurring on satellites from a different orbital plane containing 11 other satellites. That means were saw Iridium flares every nine minutes under Alpha and Beta Centauri and another set of Iridium flares every nine minutes near the tip of the tail of Scorpio, resulting in 2 flares every 9 minutes!

Moon over the geodesic dome

I have been in communication with one of the first winterovers at the French-Italian station named Concordia at Dome C.  Dome C is one of the highest points in the Antarctic plateau and is colder than South Pole and this is the first group ever to winter there. For information on dome C and reasons why it is a good place for scientific research check out the facts from one of the winterovers there.    Dome C facts      

Here is a panorama of Dome C and station Concordia along with G. Dargaud's website and the Concordia station site.
Panorama of Concordia Station (photo by Guillaume Dargaud)       winterover at Dumont d'Urville     

Finally, here is a bit of South Pole winterover trivia from Bill Spindler's website.           winterover trivia                

NEXT MONTH:  midwinter at the Pole

      A Real-Time Photo of South Pole Station as Seen from the ARO Building (live when satellite is up)

      A Comprehensive South Pole Web Site by Bill Spindler

       Winterover Web Pages (Bill Spindler's List)