Space portals allowing travelers to navigate vast distances between the stars have long been a theme in popular science fictions stories such as Stargate.
And now a NASA-funded researcher at the University of Iowa has managed to locate a portal category which he describes as X-points or electron diffusion regions.
"They're places where the magnetic field of Earth connects to the magnetic field of the Sun, creating an uninterrupted path leading from our own planet to the sun's atmosphere 93 million miles away," explained plasma physicist Jack Scudder.
Observations by NASA's THEMIS spacecraft and Europe's Cluster probes suggest the magnetic portals open and close dozens of times each day. Typically located a few tens of thousands of kilometers from Earth where the geomagnetic field meets the onrushing solar wind, most portals are small and short-lived, while others are yawning, vast and sustained. Tons of energetic particles typically flow through the openings, heating Earth's upper atmosphere, sparking geomagnetic storms and igniting bright polar auroras.
NASA is planning a mission called "MMS," or Magnetospheric Multiscale Mission to study the phenomenon. Due to launch in 2014, the four MMS spacecraft will spread out in Earth's magnetosphere and surround the portals to observe how they function.
However, there is just one problem. Finding them will be difficult, as magnetic portals are invisible, unstable, and elusive, often opening and closing without warning.
Nevertheless, Scudder says he has found portal "signposts" that will help astronomers locate and observe the phenomenon. Indeed, portals form via the process of magnetic reconnection - as mingling lines of magnetic force from the sun and Earth criss-cross, joining to create the openings.
"'X-points' are where the criss-cross takes place," said Scudder. "The sudden joining of magnetic fields can propel jets of charged particles from the X-point, creating an electron diffusion region. In the late 1990s, NASA's Polar spacecraft spent years in Earth's magnetosphere and it encountered many X-points during its mission."
Data from NASA's Polar spacecraft, circa 1998, helped provide crucial clues to tracking down magnetic X-points. Because Polar was equipped with sensors similar to those of MMS, Scudder decided to see how an X-point looked to Polar.
"Using Polar data, we found five simple combinations of magnetic field and energetic particle measurements that tell us when we've come across an X-point or an electron diffusion region. A single spacecraft, properly instrumented, can make these measurements," he added.
Essentially, this means that a single member of the MMS constellation - using the diagnostics - will be capable of location a portal and alerting other members of the constellation.