Voyagers in Interstellar Space and Cassini at Saturn

The Voyager 1 and 2 spacecraft were launched in 1977. Both carry charged particle

instruments built by the University of Maryland Space Physics Group. Voyager 1 has

(probably) entered interstellar space, crossing the heliopause on Aug. 25, 2012 at a

distance of 122 AU from the Sun. Voyager 2, traveling 3.3 AU/year and currently at 109

AU, has not yet reached the heliopause. Both Voyagers explored the magnetospheres of

Jupiter and Saturn (also Uranus and Neptune for Voyager 2) during flybys on their way

out of the solar system. Another of the many space instruments built by the Space

Physics Group was carried on the Cassini spacecraft, which was launched in 1997 and

went into orbit about Saturn in 2004. That mission is scheduled to end on Sept. 15, 2017,

with a dive into Saturn’s atmosphere after a “Grand Finale” during which Cassini will zip

between Saturn and its innermost ring 22 times. I will discuss some of the Voyager and

Cassini discoveries at Saturn and in the outer heliosphere and what might be expected

during the final years of these missions (possibly another 10 years for the Voyagers).