Voyager Has Left The Solar System (This Time For Real!)
Stop us if you've heard this one: A spacecraft flies out of the solar system ...
Yes, the planetary probe Voyager 1, launched in the era of Jimmy Carter and bell-bottoms, has finally left the room, so to speak, years after completing its primary mission: a "grand tour" of the gas giants Jupiter and Saturn (twin Voyager 2 also visited Uranus and Neptune).
And years after we first started talking about its departure.
Rewind to 2003. NPR's Richard Harris reported that Voyager 1 is "starting to probe the outermost edge of the solar system."
That's the first of many stories we've done over the years anticipating Voyager's arrival at the mysterious boundary called the heliopause, a region of space where the solar wind dies out and interstellar space begins.
In 2005, Edward Stone, Voyager's chief scientist, told All Things Considered host Melissa Block that the probe had reached "a turbulent zone" roughly marking the edge of the solar system.
Jump ahead to 2010 and listen to an interview with astronomer Neil deGrasse Tyson on the subject of the probe's imminent departure.
Just in the last year or so, we've done six more stories in what might be dubbed "Voyager's long goodbye":
June 21, 2012: A Final Voyage, Into The Wild Black Yonder
July 22, 2012: Voyager 1 Bids Farewell to the Solar System
Sept. 5, 2012: After 35 Years, Voyager Nears Edge Of Solar System
Dec. 4, 2012: NASA's Voyager 1 Reaches The 'Magnetic Highway'
Aug. 19, 2013: Has Voyager 1 Left The Solar System?
Aug. 25, 2013: Far Out: Voyager 1 Might Be Over The Edge, Into Deep Space
The problem is, that "it's not that clear because there's no signpost telling you that you're now leaving the solar system," Arik Posner, Voyager's program scientist, told me in an interview last year.
Signpost or no signpost, Posner and others now say (and are pretty confident this time) that Voyager crossed over the boundary (drumroll ...) more than a year ago — Aug. 25, 2012, to be precise.
Which leads us to Thursday's fairly definitive headline: See Ya, Voyager: Probe Has Finally Entered Interstellar Space.
And just in time: Voyager 2, a few billion miles behind Voyager 1, is nearing the edge of the solar system.