E-Mail ITHACA, N.Y. - Voyager 1 - one of two sibling NASA spacecraft launched 44 years ago and now the most distant human-made object in space - still works and zooms toward infinity. The craft has long since zipped past the edge of the solar system through the heliopause - the solar system's border with interstellar space - into the interstellar medium. Now, its instruments have detected the constant drone of interstellar gas (plasma waves), according to Cornell University-led research published in Nature Astronomy. Examining data slowly sent back from more than 14 billion miles away, Stella Koch Ocker, a Cornell doctoral student in astronomy, has uncovered the emission. "It's very faint and monotone, because it is in a narrow frequency bandwidth," Ocker said. "We're detecting the faint, persistent hum of interstellar gas."