Voyager 1 Nearing Interstellar Space
August 5, 2012

Voyager 1 Close To Crossing Into Interstellar Space

[ Watch the Video: Voyager 1 at the Final Frontier ]

redOrbit Staff & Wire Reports - Your Universe Online

The levels of high-energy cosmic rays originating from outside our solar system and the levels of lower-energy particles originating from within have been undergoing changes at a faster rate than at any other time in the past seven years, NASA officials announced on Friday.

Citing data obtained from the Voyager 1 spacecraft, the US space agency revealed that there was a five-percent jump in the high-energy rays on July 28, and that later on that day, the lower-energy particles dropped by 50%.

Three days later, however, both sets of readings, which experts say are among the three key signs of changes anticipated at the boundary of interstellar space, had normalized, officials from the NASA Jet Propulsion Laboratory (JPL) in California explained.

Scientists are currently analyzing data relating to the third of those signposts, the direction of the magnetic field, in order to see whether or not it, too, had changed. The preliminary analysis of that information is expected to come sometime in the next month.

"These are thrilling times for the Voyager team as we try to understand the quickening pace of changes as Voyager 1 approaches the edge of interstellar space," Edward Stone, a Voyager project scientist based at the California Institute of Technology, said in a statement.

"We are certainly in a new region at the edge of the solar system where things are changing rapidly. But we are not yet able to say that Voyager 1 has entered interstellar space," he added.

The levels of the high-energy cosmic ray particles had been increasing for years, but the recent growth has been occurring at a much faster rate, the scientists explained. The last spike came in May and was just five percent. Likewise, the lower-energy particle levels have been declining over the past 24 months, and they are expected to become close to zero by the time Voyager 1 actually crosses into interstellar space.

"The increase and the decrease are sharper than we've seen before, but that's also what we said about the May data," Stone said. "The data are changing in ways that we didn't expect, but Voyager has always surprised us with new discoveries."

Voyager 1, which was launched along with Voyager 2 in 1977, is currently 11 billion miles from the sun -- slightly less than 2 billion miles ahead of its younger sibling. Both of the 35-year-old probes "will cross into interstellar space," JPL Voyager Project Manager Suzanne Dodd said. "It's just a question of when."