NASA is now two for two in regard to a huge achievement in space. Voyager 2 has become only the second man-made object to enter interstellar space, or the "space between the stars," as a release from the agency's Jet Propulsion Laboratory puts it. The first was its sister ship, Voyager 1, which crossed the boundary in 2012. Details and developments:
- Long mission: Voyager 2 launched in August of 1977 on a mission to study the outer planets in our solar system. (Voyager 1 went up about two weeks later, but on a different trajectory.) In fact, Voyager 2 is the only spacecraft to have studied the gas giants Jupiter, Saturn, Uranus, and Neptune, reports Space.com. After that part of the mission wrapped up decades ago, NASA steered the craft toward deep space.
- Still transmitting: One key difference between Voyagers 1 and 2 is that 2 still has a working instrument that is expected to provide "first-of-its-kind observations" from the journey, per JPL. The same instrument (the Plasma Science Experiment) conked out on Voyager 1 long before it crossed the boundary.
- Video: NASA scientists explain the mission and the milestone in this video.