Important Missions for Solar System Exploration

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Important Missions for Solar System Exploration

• An overview from early 50s to today
• Part III

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Mariner 8 05.09.71
Mariner-71H (also called Mariner-H) was the
first of a pair of American spacecraft intended
to explore the physical and dynamic
characteristics of Mars from Martian orbit. The
overall goals of the series were to search for an
environment that could support life to collect
data on the origin and evolution of the planet
to gather information on planetary physics,
geology, planetology, and cosmology and to
provide data that could aid future spacecraft
such as the Viking Landers.
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Mariner 9 05.30.71
Mariner 9 was the first spacecraft to orbit
another planet. It carried an instrument payload
similar to Mariners 6 and 7, but, because of the
need for a larger propulsion system to control
the spacecraft in Mars orbit, it weighed more
than Mariners 6 and 7 combined. When Mariner 9
arrived at Mars, the atmosphere was so dusty that
the surface was obscured. This unexpected
situation made a strong case for the desirability
of studying a planet from orbit rather than
merely flying past. Mariner 9's computer was thus
programmed from Earth to delay imaging of the
surface for a couple of months until the dust
settled. After 349 days in orbit, Mariner 9 had
transmitted 7,329 images, covering over 80 of
Mars' surface. The images revealed river beds,
craters, massive extinct volcanoes, canyons
including Valles Marineris, a massive system of
canyons over 4,000 kilometers about 2,500 miles
long. The vast chasm is named in honor of the
spacecraft. Mariner 9 also found evidence of wind
and water erosion and deposition, weather fronts,
fogs, and more. Mars' tiny moons, Phobos and
Deimos, were also photographed. The findings from
the Mariner 9 missions laid the groundwork for
the Viking program.
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Pioneer 10 03.02.72
Pioneer 10 was the first spacecraft to travel
through the asteroid belt and reach the outer
solar system, flying past Jupiter at a distance
of about 130,354 km (81,000 miles) from the
cloudtops. During its Jupiter encounter, Pioneer
10 imaged the planet and its moons, and took
measurements of Jupiter's magnetosphere,
radiation belts, magnetic field, atmosphere, and
interior. These measurements of the intense
radiation environment near Jupiter were crucial
in designing the Voyager and Galileo spacecraft.
Also, as the first spacecraft to use a planetary
gravity assist to change its velocity, Pioneer 10
then headed out of the solar system in the
direction opposite to the Sun's motion through
the Milky Way galaxy. Except for Voyager 1, which
is travelling in the opposite direction, Pioneer
10 is farther from Earth than any other human
artifact. Even so, it will take another 2 million
years for Pioneer 10 to reach the first star on
its trajectory. Pioneer 10 carries a plaque
intended to communicate something about its home
planet should the spacecraft ever meet up with
another intelligent species. Routine tracking of
Pioneer 10 ended in 1997, but the spacecraft
continued to send out signals until January 2003.
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Pioneer 11 04.05.73
Pioneer 11 was the second spacecraft (following
Pioneer 10) to visit the outer solar system and
the first spacecraft to visit Saturn. Borrowing
momentum from Jupiter during its flyby, Pioneer
11 was hurled above the ecliptic (the plane in
which most of the planets orbit the Sun) on a
trajectory that brough it about 22,000 km (13,000
miles) from Saturn. It took close-up pictures and
discovered an additional ring.
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Mariner 10 11.03.73
Mariner 10 was the first spacecraft to use a
gravity assist trajectory, accelerating as it
entered the gravitational influence of Venus,
then being flung by the planet's gravity onto a
slightly different course to reach Mercury. It
was also the first spacecraft to encounter two
planets at close range. Placed into orbit around
the Sun going in the opposite direction from
Earth's orbit, Mariner 10's orbit crossed
Mercury's the first time at a distance of 703
kilometers (437 miles) from the planet, the
second time at 48,069 kilometers (29,870 miles),
and a third time at 327 kilometers (203 miles).
In total, Mariner 10 imaged about half the
planet. Mercury was revealed to have a very
cratered, Moon-like surface and a faint, mostly
helium atmosphere.
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Helios 1 11.10.74
Helios 1 was a joint German- American deep space
mission to study the main solar processes and
solar-terrestrial relationships. Specifically,
the spacecraft's instruments were designed to
investigate phenomena such as solar wind,
magnetic and electric fields, cosmic rays, and
cosmic dust in regions between Earth's orbit and
approximately 0.3 AU from the Sun.
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Viking 1 08.20.75
The Viking Mars mission was performed by two
spacecraft, Viking 1 and Viking 2, launched
within a couple of weeks of each other. Each
spacecraft consisted of an orbiter and a lander,
which traveled attached together for nearly a
year to reach Mars orbit. The orbiters then began
taking pictures of the Martian surface, from
which a landing site was selected. The landers
then separated from the orbiters and soft landed.
The orbiters continued imaging and, between
Viking 1 and Viking 2, imaged the entire planet
at what was then high resolution. The orbiters
also conducted atmospheric water vapor
measurements and infrared thermal mapping. The
Viking 1 orbiter flew within 90 kilometers of
Phobos to take images of this larger, inner moon
of Mars. The Viking landers took full 360-degree
pictures, collected and analyzed samples of the
Martian soil, and monitored the temperature, wind
direction, and wind speed. The Viking missions
revealed further details of volcanoes, lava
plains, huge canyons, and the effects of wind and
water. Analysis of the soils at the landing sites
showed them to be rich in iron, but devoid of any
signs of life.
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Viking 2 09.09.75
The Viking Mars mission was performed by two
spacecraft, Viking 1 and Viking 2, launched
within a couple of weeks of each other. Each
spacecraft consisted of an orbiter and a lander,
which traveled attached together for nearly a
year to reach Mars orbit. The orbiters then began
taking pictures of the Martian surface, from
which a landing site was selected. The landers
then separated from the orbiters and soft landed.
The orbiters continued imaging and, between
Viking 1 and Viking 2, imaged the entire planet
at what was then high resolution. The orbiters
also conducted atmospheric water vapor
measurements and infrared thermal mapping. The
Viking 2 orbiter flew within 22 kilometers of
Deimos and took high-resolution pictures of this
smaller of the two moons of Mars. Unlike the
Viking 1 orbiter, the orbit of Viking 2 was
inclined well above the equator so that it could
better study the polar regions. The Viking
landers took full 360-degree pictures, collected
and analyzed samples of the Martian soil, and
monitored the temperature, wind direction, and
wind speed. The Viking missions revealed further
details of volcanoes, lava plains, huge canyons,
and the effects of wind and water. Analysis of
the soils at the landing sites showed them to be
rich in iron, but devoid of any signs of life.
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Helios 2 01.15.76
Helios 2 was the second spacecraft launched to
investigate solar processes as part of a
cooperative project between the Federal Republic
of Germany and the United States in which the
former provided the spacecraft and the latter the
launch vehicle.
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Voyager 1 09.05.77
After historic visits of to Jupiter and Saturn,
Voyager 1 is now on course to be the first
human-made object to leave our solar system. In
space for more than 25 years, it has already
traveled farther from our Sun than any other
spacecraft. It is not clear when Voyager 1 will
reach the heliopause boundary, where the
influence of our Sun ends. The boundary is
thought to exist somewhere from 8 to 22.5 billion
kilometers (5 to 14 billion miles) from the Sun.
When Voyager 1 does cross over, scientists will
be able to measure the interstellar environment
without the influence of the Sun for the first
time.
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Voyager 2 08.20.77
As of September 2003, Voyager 2 was about
10,657,000,000 km (6,622,000,000 miles) from our
Sun. Even at speeds of more than 56,000 kph
(35,000 mph), it will take nearly 20,000 years
for the Voyagers to reach the middle of the comet
swarm and possibly twice this long for them to
pass the outer boundaries of cometary space. By
this time, they will have traveled a distance of
two light-years, equivalent to half of the
distance to Proxima Centauri, the nearest star.
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Pioneer Venus 05.20.78
The Pioneer Venus mission had two components an
orbiter and a multiprobe. These spacecraft were
launched separately, the orbiter arriving at
Venus just a few days ahead of the multiprobe.
The orbiter carried 17 experiments, including
instruments to see through the clouds and map the
surface, as well as measure cloud distribution,
atmospheric composition, the magnetic field, the
solar wind, properties of the ionosphere of
Venus, the gravity field, and gamma ray bursts.
The multiprobe spacecraft was actually four
separate atmospheric probes hitching a ride on a
spacecraft bus. The probes separated from the bus
12.9 million kilometers (8 million miles) before
arrival at Venus and entered the atmosphere in
different regions of the planet at the same time.
The probes made measurements of the structure and
composition of the atmosphere all the way to the
surface. Meanwhile, the probe bus made
measurements in the upper atmosphere, and the
Orbiter simultaneously made measurements for
comparison.
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ISEE-3/ICE 08.12.78

• International Sun-Earth Explorer 3's was part of
  a trio of spacecraft sent into space to study
  interplanetary space. It was the first spacecraft
  orbit at a libration point and also the first to
  detect the solar wind approaching Earth.
• It was later renamed International Cometary
  Explorer and sent to study comet Giacbini-Zinner
  and comet Halley. When last contacted, the
  spacecraft was on a trajectory that will bring it
  close to Earth in August 2014. It could possibly
  be recaptured, returned to Earth and ultimately
  be displayed at the Smithsonian Institution.