Pioneer 11 (also known as Pioneer G) is a 259 kg (571 lb) 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.[1] 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.[2][3] Its companion, Pioneer 10, kept transmitting until 2005.


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  3. Pioneer 11: In Depth. Retrieved on 10 December 2017.