Posted: Fri, Sep 13, 2013, 10:15 AM ET (1415 GMT)
NASA's Voyager 1 spacecraft has cross the heliopause and is now in interstellar space, the first spacecraft to do so, project scientists confirmed on Thursday. In a paper published in the journal Science, space scientists said their analysis of data returned by instruments on the 36-year-old spacecraft indicated that the spacecraft had crossed the heliopause, the boundary between solar and interstellar plasma, in August of last year. The plasma data coincided with an abrupt change in energetic particles detected by the spacecraft on August 25, 2012. Scientists had been anticipating for years the passage of Voyager 1 into interstellar space, although project officials has rejected two reports earlier this year that suggested the spacecraft already had passed through the heliopause. Voyager 1, powered by an RTG, should be able to continue to return data on the space environment until 2020.

Related Links:

•  Washington Post article
•  SPACE.com article
•  New York Times article
•  AP article
•  NASA press release