NASA's Pioneer programme, started in the 1950s, launched a series of spacecraft to a number of destinations in the Solar System. As the name suggests, Pioneer missions paved the way for later probes.
Important members of the Pioneer family include Pioneer 4, which flew by the Moon in 1959, and Pioneers 6-9, the first network of Sun-monitoring satellites.
Launched in 1972, Pioneer 10 was the first mission to Jupiter and the first probe to travel beyond Neptune. In 1979 Pioneer 11 became the first craft to visit Saturn. The 1978 Pioneer Venus missions (12 and 13) were the first long-term American Venus missions.
Photo: Artist's impression of Pioneer 11 (NASA)
Trailblazing missions travel across the Solar System.
Sir Patrick Moore talks about Pioneer 13's mission.
Sir Patrick Moore describes the Pioneer 13 probe's findings in a 1982 edition of the Sky at Night. He talks about volcanism on the planet and the hostile conditions at the surface. Though Sir Patrick speaks about active volcanism on Venus, a volcanic eruption has not been witnessed there.
Scientists propose competing theories to explain Venusian geology.
The Pioneer missions to Venus (Pioneer 12 and 13), launched in 1978, investigated the planet's atmosphere and created a crude radar map of the surface. The findings lead scientists to develop competing theories about the geological processes that shaped the Venusian surface. A later mission called Magellan would provide more information for geologists and lead to new theories.
Earth and Venus are alike in some ways - so why is Venus so hot?
Launched in 1978, the American Pioneer Venus probes (Pioneer 12 and 13) tried to find out why Venus is so much hotter than theory predicted it should be given its distance from the Sun. Using data from the mission, scientists created computer models that suggested that early water on the Venusian surface boiled away to form a thick, insulating atmosphere that trapped heat.
Sir Patrick Moore discusses Pioneer's long journey to Saturn.
Sir Patrick Moore and his guest Dr Garry Hunt of University College London discuss Pioneer 11's arrival at Saturn in 1979. It took the first close-up photographs of Saturn, saw Jupiter's Great Red Spot and returned data about the solar wind. Like Pioneer 10, a major part of the probe's mission was to discover potential hazards awaiting later missions such as the Voyager 1 and 2 probes.
Patrick Moore discusses the search for life with Sagan.
Sir Patrick Moore spoke to Dr Carl Sagan in 1974 about the search for other civilisations.
The Pioneer program is a series of United States unmanned space missions that were designed for planetary exploration. There were a number of such missions in the program, but the most notable were Pioneer 10 and Pioneer 11, which explored the outer planets and left the solar system. Pioneer 10 and Pioneer 11 carry a golden plaque, depicting a man and a woman and information about the origin and the creators of the probes, should any extraterrestrials find them someday.