Good question about Halleys Comet, I couldn't find anything sig. about it except this:
The last perihelion passage of the comet was on February 9, 1986. In March 1986, six uncrewed spacecraft encountered Halley's Comet and produced data that have greatly enhanced the understanding of comets. The comet will return to its perihelion in 2061.Is there any danger from Comet Halley?
"Before anyone understood the nature and orbits of comets, people worried about the effects a comet might have on us. Today we know enough about these objects to provide a reassuring "environmental impact statement.'' Unless a comet physically collides with the Earth (which Halley will be far from doing), these small chunks of dirty ice pose no danger to us. Their effects are on the mind, stimulating our curiosity and kindling our imaginations".