Other space probes had their instruments examining Halley's Comet:
Pioneer 7 was launched on August 17, 1966. It was put into heliocentric orbit with a mean distance of 1.1 AU to study the solar magnetic field, the solar wind, and cosmic rays at widely separated points in solar orbit. 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.[1]
Pioneer Venus Orbiter in orbit of Venus, was positioned perfectly to take measurements of Halley's Comet during its perihelion February 9, 1986. Its UV-spectrometer observed the water loss when Halley's Comet was difficult to observe from the Earth.[2]
The Space Shuttle Challenger, on its launch on January 28, 1986, was carrying SPARTAN-203 with the mission to make observations of Halley's Comet. STS-51Lfailed to reach orbit, resulting in the total loss of crew and vehicle. That launch failure resulted in the cancellation of dozens of subsequent shuttle missions, including the next scheduled launch, STS-61-E, planned for March 6, 1986, with a payload including the ASTRO-1 observatory, which was intended to make astronomical observations of Halley's Comet.
Any observations of Halley's Comet made by the crew of Soyuz T-15, which made the first trip to the Mirspace station and the last to Salyut 7 in March 1986, are unknown.
