Is the Voyager 1 spacecraft in interstellar space? NASA says yes, but a small but respected community of researchers isn’t convinced.
A quick review of the facts: Last year, NASA scientists penned a research paper that concluded the spacecraft, traveling at 38,000 mph, became the first man-made object to leave the solar system sometime around August 25, 2012.
The article’s authors, who based their announcement on a number of advanced models, stated “after long disagreements, that is now the consensus view of Voyager mission team leaders.”
One contrary model put forward recently in the journal Geophysical Research Letters argues that a phenomenon in which our sun’s wind gets compressed at the solar system’s end could mislead scientists looking at the data. If this model is correct, Voyager has yet to cross out of the region of the sun’s influence, called the heliosphere (the solar system is defined as a much larger area that extends beyond an icy belt called Oort Cloud, which is 50,000 times further from the sun than Earth).
“It is the nature of the scientific process that alternative theories are developed in order to account for new observations,” says Ed Stone, NASA’s lead Voyager project scientist. “This paper differs from other models of the solar wind and the heliosphere and is among the new models that the Voyager team will be studying as more data are acquired by Voyager.”
Voyager launched on Sept. 5, 1977 for a mission to the gas giants.
One element of the Voyager mission isn’t under debate, though: the 35-year old spacecraft is still relying on GE technology, including command computers and power generators.
The spacecraft is now than 11.9 billion miles from home—more than 53,000 times farther than a trip to the moon. The Voyager 1 and its sibling the Voyager 2 launched in 1977. They were expected to last only a few years, but carried . “NASA considered everything past the Saturn encounter a bonus,” said Dr. Howard Butler, who ran GE’s Aerospace Electronic Systems Department.
NASA now estimates that the probes will survive until 2025. Each probe holds a special phonograph record, a 12-inch encoded gold-plated copper disc containing music, sounds and images selected to portray the diversity of life and culture on Earth, from Bach and Chuck Berry to birds, heartbeat, and laughter.
Voyager’s gold record, “The Sights and Sounds of Earth.”
GE engineers designed the Voyagers’ command computers directing the flight path and providing communication links with NASA Mission Control, as well as the probes’ power source called radioisotope thermoelectric generators (RTGs). These devices still remain in service and convert the heat produced from the natural radioactive decay of plutonium into electricity for the spacecraft’s instruments, computers, radio and other systems.
Scientists have been speculating for several years about the exact timing spacecraft’s departure from the heliosphere, the limit of the particles thrown off by the sun. Last October, GE’s science and technology publication Txchnologist noted that since September 2012, the craft’s instruments have sensed a major, sustained drop in the low-energy charged particles released by the sun that reach it. The prediction was about five days off: the exact date of departure was Aug. 25, 2012.
Top image: The original paths of Voyager 1 and 2. All GIFs Courtesy NASA/JPL-Caltech.