NASA VOYAGER: 'TSUNAMI WAVE' STILL FLIES THROUGH INTERSTELLAR SPACE
The Voyager 1 spacecraft has experienced three shock waves. The most recent shock wave, first observed in February 2014, still appears to be going on. One wave, previously reported, helped researchers determine that Voyager 1 had entered interstellar space.
The "tsunami wave" that NASA's Voyager 1 spacecraft began experiencing earlier this year is still propagating outward, according to new results. It is the longest-lasting shock wave that researchers have seen in interstellar space.
"Most people would have thought the interstellar medium would have been smooth and quiet. But these shock waves seem to be more common than we thought," said Don Gurnett, professor of physics at the University of Iowa in Iowa City. Gurnett presented the new data Monday, Dec. 15 at the American Geophysical Union meeting in San Francisco.
A "tsunami wave" occurs when the sun emits a coronal mass ejection, throwing out a magnetic cloud of plasma from its surface. This generates a wave of pressure. When the wave runs into the interstellar plasma -- the charged particles found in the space between the stars -- a shock wave results that perturbs the plasma.
"The tsunami causes the ionized gas that is out there to resonate -- "sing" or vibrate like a bell," said Ed Stone, project scientist for the Voyager mission based at California Institute of Technology in Pasadena.
An audio clip with a graphical representation is online at:
http://www.jpl.nasa.gov/video/details.php?id=1347
This is the third shock wave that Voyager 1 has experienced. The first event was in October to November of 2012, and the second wave in April to May of 2013 revealed an even higher plasma density. Voyager 1 detected the most recent event in February, and it is still going on as of November data. The spacecraft has moved outward 250 million miles (400 million kilometers) during the third event.
"This remarkable event raises...