Pioneer is the name of the space program by Nasa that sent unmanned
spacecraft around our solar system. The program was a direct result of the
Soviet program that produced Sputnik I and II and also the American
Explorer program. These made scientists realize that the environment
surrounding our planet is a very complex system of electromagnetism and
particles. The Pioneer program was started with the explicit goal of
studying the magnetic environment outside Earth.
Pioneer 1, Pioneer 2 and Pioneer 3 were all sent to the moon, but they all
failed and fell back onto earth, where they burnt as they entered the atmosphere.
Pioneer 3 did manage to discover and send some data about the van Allen
belts,
which were unknown at the time, however. Pioneer 4 and Pioneer 5 were sent into
orbits circling the Sun, and returned data about the structure, activity,
magnetic field and solar winds. They also functioned as test probes for
space communications.
Pioneer's 6 through Pioneer 9 introduced the concept of spinning the spacecraft,
which made them easier to control and navigate. These passed the sun and took
orbit about the distance of the Earth from the Sun, 1 AU. Before these probes,
scientists believed that space was filled with cosmic dust which would make
space travel dangerous. This turned out not to be true. At least until now, when
there's plenty of dead satellites out there...
Anyhow, Pioneer 10 followed, and this time Jupiter was the target. The 10
became the first man made spacecraft to pass the Asteroid Belt between Mars
and Jupiter. It would study the gas giant and its moons. After doing this, it
would catapult out of the solar system, using the planet's gravity as a
slingshot. Pioneer 10 also brought with it a message of its origin, intended for
distant civilizations or intelligences. Pioneer 11 followed with a similar
task and both these probes returned unique and valuable information about the
structure and origins of the outer planets.
Pioneer 11 was targeted to intercept Saturn once it had passed Jupiter. In
order to do this, the track it took through space brought it very close to
Jupiter, giving new pictures and data about the surface and the polar regions.
Since Saturn is twice as far from the Sun as Jupiter, the data that had been
collected from Earth was fairly inaccurate. The two Pioneers sent back huge
amounts of data, which has been invaluable in understanding the origins of the
planets and our solar system. Besides this, a vast amount of moons and rings
were discovered.
Make sure you read fiddlesticks' excellent writeups on Pioneer 10 and 11.
Pioneer 12 and Pioneer 13 were sent to Venus, our closest neighbor, and
they provided a radar image of the planet's surface. Pioneer 13 sent probes down
to the surface, examining the atmosphere and clouds and the environment on the
plants. Venus' is entirely covered with a thick layer of clouds, so little can
be studied by optical means.
Today, Pioneer 10 and 11 has now left the solar system, and are traveling at
the speed of 12 km/s (7.5 miles/s). After 30 years in space, number 10 still transmits
data, even though the signal is getting hard to interpret. Number 11 is now
silent, awaiting for some distant civilization to find it and listen to its
recordings from Earth. It'll be some 4 million years before it reaches the stars
of constellation Aquila. Pioneer 6 is still out there orbiting the Sun and a
brief contact was made on its 35th anniversary last year. Not bad for something
built to function for 6 months...
Name Launch Date Mission Status
Pioneer 1 11 Oct. 1958 Moon reached 2,765 mi. altitude
Pioneer 2 8 Nov. 1958 Moon reached 963 mi. altitude
Pioneer 3 6 Dec. 1958 Moon reached 63,580 mi. altitude
Pioneer 4 3 Mar. 1959 Moon passed 37,300 mi. from Moon, entered solar orbit
Pioneer 5 11 Mar. 1960 Solar Orbit Entered solar orbit, in function for 106 days
Pioneer 6 16 Dec. 1965 Solar Orbit Still Operating, last contact 2000
Pioneer 7 17 Aug. 1966 Solar Orbit Still Operating, last contact 1995
Pioneer 8 13 Dec. 1967 Solar Orbit Still Operating, last contact 1996
Pioneer 9 8 Nov. 1968 Solar Orbit Signal lost in 1983
Pioneer E 7 Aug. 1969 Solar Orbit Launch failure
Pioneer 10 2 Mar. 1972 Jupiter Still operating in outer Solar System, signals very weak
Pioneer 11 5 Apr. 1973 Jupiter Continued to Saturn and still operating, signal lost 1995
Pioneer 12 20 May 1978 Venus Still operating in orbit around Venus
Pioneer 13 8 Aug. 1978 Venus Successful entry of four probes and bus into atmosphere of Venus
Source: ne.se, nasa