CHARLESTON, W.Va. -- On the same day NASA officials announced that Voyager 1 had become the first spacecraft to leave the solar system, the National Radio Astronomy Observatory announced that its Green Bank Telescope had pinpointed Voyager's radio signal more than 11 billion miles away.
On Thursday, NASA announced that 36 years after its launch, the plutonium-powered spacecraft had passed through the heliosphere -- the hot plasma bubble surrounding the solar system -- and escaped the sun's influence.
Voyager 1, headed away from the sun at a speed of about 38,000 miles per hour, will continue to observe exotic particles from never-explored parts of the universe, and radio data back to Earth.
While NASA's Jet Propulsion Laboratory continually tracks Voyager using a network of antennas and communication facilities located in California, Spain and Australia, NRAO astronomers believe they can locate Voyager's position on the sky with unprecedented precision.
Although Voyager's main transmitter operates at only 22 watts -- about the same power used by a car-mounted police radio or a refrigerator light bulb -- its signal is extremely strong when compared to most natural objects studied by radio telescopes.
West Virginia's Green Bank Telescope easily detected Voyager's signal, picking it out from background radio noise in less than one second, according to the NRAO.
"Voyager is the first manmade object to penetrate the interstellar medium, and we really want to be able to receive the data from this new frontier," NRAO scientist Toney Minter, who oversaw the Green Bank observations, said in a news release. "This information will provide many clues about how the interstellar medium behaves and how the sun interacts with it."
Scientists using the NRAO's Very Long Baseline Array, a network of 10 radio antennae stretching from Hawaii to the Virgin Islands, also pinpointed Voyager's position. The VLBA, which operates as a single telescope, spotted the spacecraft very near its predicted location.
Observations by the VLBA taken of Voyager after it passed through the heliosphere earlier this year may have been accurate to the milliarcsecond level, with one milliarcsecond equaling an area about 50 miles across, when taken from a distance of 11.5 billion miles.
"The ability to pinpoint the location of Voyager and other spacecraft is critical as we explore the inner solar system and beyond," said Walter Brisken, the NRAO scientist who directed the VLBA observations.
Last year, a National Science Foundation committee included both the Green Bank Telescope and the VLBA in a list of observatories to be cut off from NSF funding by 2017 in an effort to cut costs while achieving as many scientific goals as possible.
Reach Rick Steelhammer at rsteelham...@wvgazette.com or 304-348-5169.