These craft range in
distance from above Earth’s
atmosphere to Sun-Earth
L1 and on to the outskirts of
the heliosphere (the volume
of space controlled by the
Sun’s magnetic field and
solar wind). Most of them
are observatories but some
carry instruments to directly
measure the environment they
are in.
It is notable that Voyager
1 ended its studies of the
heliosphere in 2012 when
it entered interstellar space.
COURTESY OF NASA/JPL-Caltech
It is escaping the Sun but
This
artist’s
concept
depicts
NASA’s
Voyager
1
spacecraft
entering
interstellar
space.
is still influenced by solar
gravity while it sails through
mission since 2004. The Huygens probe explored
the interstellar medium. It will continue making
Titan’s atmosphere and surface in January 2005 before
measurements of this new environment
succumbing to the extreme cold there. Cassini has
By simply probably into the 2020s before its power
wanes too much for instrument operations. continued its orbital tour of the Saturnian system and
observing other Presently there are no spacecraft
is scheduled to end in September 2017, diving through
planets and operating at Mercury. Studies of Venus are the ring system three times before entering Saturn’s
being carried out by the Japanese atmosphere.
other planetary currently
Uranus and Neptune have not been visited since
Akatsuki orbiter.
systems, we gain Robotic exploration of the Moon has been NASA’s Voyager 2 went by them in 1986 and 1989,
respectively. But the outer Solar System hasn’t been
perspective. By revived over the last 25 years. NASA’s
entirely without monitors as the Voyagers cruised
Lunar Reconnaissance Orbiter continues
understanding monitoring our nearest neighbor in space through the heliosphere. In 2015, NASA’s New
Horizons made a successful flyby of the Pluto system
our neighbors, we even after additional missions from
returning eye-popping images of a dwarf planet that is
NASA and other nations have ended their
better understand activities.
apparently far more active than anyone would imagine
for an object so far from the Sun. If additional funding
The
last
of
the
terrestrial
(rocky)
our home.
is granted, New Horiz