Magnetosphere of Jupiter By 1973 the magnetic moment was known within a factor of two, whereas the tilt was correctly estimated at about 10°. The modulation of Jupiter's DAM by Io (the so-called Io-DAM) was discovered in 1964, and allowed Jupiter's rotation period to be precisely determined. The definitive discovery of the Jovian magnetic field occurred in December 1973, when the Pioneer 10 spacecraft flew near the planet. As of 2009 a total of eight spacecraft have flown around Jupiter and all have contributed to the present knowledge of the Jovian magnetosphere. The first space probe to reach Jupiter was Pioneer 10 in
Helena Russell stated his given name was 'Telford'.) In 1994, Helena was widowed when Lee Russell departed on the Astro Seven mission to Jupiter and never returned. All hands of the mission were declared dead. The couple never had children. After her husband's death, she was employed on Earth by the World Space Commission. In 1997, she was part of a team evaluating the mental state of Captain Tony Cellini. Cellini, the sole survivor of the Ultra Probe mission, returned to Earth speaking of his ordeal with a deadly space 'dragon' lifeform in a spaceship graveyard on the far side of planet