has the second one explored any other planets?
Yes. Saturn
Pioneer 11
It was the first probe to encounter Saturn and the second to fly through the asteroid belt and by Jupiter.
what is magnetosphere of jupiter? The cavity created in the solar wind by the planet's magnetic field how big is the cavity? It extends up to seven million kilometers in the Sun's direction and almost to the orbit of Saturn in the opposite direction which scientist discovered it? UNANSWERABLE were there any exploration done to study on this? Until 2009 eight spacecraft have flown around Jupiter including Pioneer 10, Pioneer 11, Voyager 1 and  Voyager 2 any spacecraft which carried passengers? No. Only automated spacecraft have visited Jupiter
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Pioneer 11 [SEP] Introduction
Pioneer 11 (also known as Pioneer G) is a robotic space probe launched by NASA on April 6, 1973 to study the asteroid belt, the environment around Jupiter and Saturn, solar wind and cosmic rays. It was the first probe to encounter Saturn and the second to fly through the asteroid belt and by Jupiter. Thereafter, "Pioneer 11" became the second of five artificial objects to achieve the escape velocity that will allow them to leave the Solar System. Due to power constraints and the vast distance to the probe, the last routine contact with the spacecraft was on September 30, 1995, and the last good engineering data was received on November 24, 1995.