Voyager Spacecraft Enters a Strange, Mysterious Region 11 Billion Miles from Earth --Upending Long-Standing Theories
Launched 36 years ago, the Voyager 1 spacecraft speeds a rate of about a million miles a day entering a bizarre and mysterious region more than 11 billion miles from Earth that scientists are struggling to make sense of. It's a region where the fierce solar winds have all but vanished and pieces of atoms blasted across the galaxy by ancient supernovae drift into the solar system, the NASA probe is causing scientists to question some long-standing theories on the nature of our solar system and life beyond its cold dark edge dubbed the "magnetic highway" --a newly discovered area of the heliosphere, the vast bubble of magnetism that shields the solar system from deadly cosmic rays.
“The models that have been thought to predict what should happen are all incorrect,” said physicist Stamatios Krimigis of the Johns Hopkins University Applied Physics Laboratory, who is lead author of one of three new papers on Voyager appearing in Science on June 27. “We essentially have absolutely no reliable roadmap of what to expect at this point.”
Voyager 1 entered the edge of the solar wind in 2003, when the spacecraft’s instruments indicated that particles around it were moving subsonically, having slowed down after traveling far from the sun. Then, toward the end of July 2012, Voyager 1's instruments reported that solar winds had suddenly dropped by half, while the strength of the magnetic field almost doubled, according to the studies. Those values then switched back and forth five times before they became fixed on Aug. 25. Since then, solar winds have all but disappeared, but the direction of the magnetic field has barely budged. This transition happened extremely fast, in a matter of a few days.
"The jumps indicate multiple crossings of a boundary unlike anything observed previously," a team of Voyager scientists wrote in one of the studies. They labeled the new area the heliosheath depletion region.
At the same time, the measurements of galactic cosmic rays increased significantly, which would be “just as we expected if we were outside the solar wind,” said physicist Ed Stone of Caltech, Voyager’s project scientist and lead author of one of the Science papers. It looked almost as if Voyager 1 had left the sun’s influence. But here's the baffling discovery: if the solar wind was completely gone, galactic cosmic rays should be streaming in from all directions.
Instead, Voyager detected an increase in galactic cosmic rays — but found that at times they were moving in parallel from one direction instead of randomly. And even though the solar particles had dropped off, the probe hasn’t measured any real change in the magnetic fields around it. That’s hard to explain because the galaxy’s magnetic field is thought to be inclined 60 degrees from the sun’s field.
"This was conceptually unthinkable for cosmic rays," said Stamatios Krimigis, a solar physicist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., and leader of another one of the studies. "There is no cosmic ray physicist I know who ever expected that they would not all be coming equally from all directions."
"This is a new region that we didn't know existed," Krimigis says. "We have no road map, and we're waiting to see what's going to happen next."
The Daily Galaxy via NASA, Wired, and the LA Times
Image credit: Southwest Research Institute