Washington: Thirty-seven years after it was launched, Voyager 1 is not only alive and kicking, but continuing its journery into the great void.
Lunched in 1977, the spacecraft has entered inter-stellar space, the first man-made object to do so, the US National Aeronautics and Space Administration (NASA) said.
Inter-stellar space is the region between the stars filled with a thin soup of charged particles, also known as plasma. NASA said last September that Voyager 1 might have left the sun`s heliosphere and entered inter-stellar space Aug 25, 2012.
"Normally, inter-stellar space is like a quiet lake," Xinhua quoted Ed Stone, the Voyager mission`s project scientist, as sayibng. "But when our sun has a burst, it sends a shock wave outward that reaches Voyager about a year later. The wave causes the plasma surrounding the spacecraft to sing."
NASA said three such waves had reached Voyager 1 since it entered inter-stellar space in 2012.
The first was too small to be noticed when it occurred and was only discovered later, but the second was clearly registered by the spacecraft`s cosmic ray instrument in March 2013.
Thanks to the second wave, the mission team acquired evidence that Voyager had been flying for more than a year through plasma that was 40 times denser than measured before -- a telltale indicator of inter-stellar space.
A third wave was registered in March this year, and data showed that the density of the plasma was similar to what was measured previously, confirming the spacecraft was in inter-stellar space.
Voyager is the only human-made probe farthest from the Earth, and the first to enter the vast sea between stars.