Pioneer 7:
Identical to Pioneer 6, Pioneer 7 was put into heliocentric orbit at 1.01 ? 1.125 AU (a little farther from the Sun than Earth's orbit) to study the solar magnetic field, the solar wind, and cosmic rays at widely separated points in solar orbit.
On 7 September 1968, the spacecraft was correctly aligned with the Sun and Earth to begin studying Earth's magnetic tail. In 1977, eleven years after its launch, Pioneer 7 registered the magnetic tail 19.3 million kilometers out, three times further into space than recorded previously.
On 20 March 1986, the spacecraft flew within 12.3 million kilometers of Halley's Comet and monitored the interaction between the cometary hydrogen tail and the solar wind. On 31 March 1995, more than 29 years after launch, the plasma analyzer was turned on during 2 hours of contact with the ground.
Along with Pioneers 6, 8, and 9,the spacecraft formed a ring of solar weather stations spaced along Earth's orbit. Measurements by the four Pioneers were used to predict solar storms for approximately 1,000 primary users, including the Federal Aviation Administration; commercial airlines; power companies; communication companies; military organizations; and entities involved in surveying, navigation, and electronic prospecting.
Pioneer 7 helped provide data used to predict solar storms.
