Mariner Meteor Mystery, Solved?

He asked Wiegert, a friend and colleague, to look into it. Wiegert began to examine old comet data and-voilà-"Mariner 4 was close to the orbit of Comet D/Swift at the time of the meteor encounter."

Amazingly, Mariner 4 was not merely close to the comet's orbit, it may have been close to the comet itself. "According to our calculations, the [possibly shattered] nucleus of D/Swift was only 20 million kilometers from the spacecraft." As distances go in the solar system, that's nearby.

Photo courtesy of NASA An artist's rendition of the Mariner 4 spacecraft.

"It's like in Star Trek when Enterprise stumbles across a comet in the middle of deep space. Of course, that's crazy," says Cooke. "Space is so big, the chances of running across a comet are almost nil." Yet this may be what happened to Mariner 4.

Mariner's cameras weren't turned on at the time, so a comet could've passed by unnoticed-except for the jostling of comet dust. Telescopes on Earth saw nothing, but that's no surprise. An old, shattered nucleus wouldn't necessarily glow. It all makes sense.

Case closed? Wiegert still has doubts. "The complicating factor is that, because D/Swift was seen for only a short time in 1895-96, its orbit is not terribly well-known. Our extrapolations could be wrong. We're in the process of collecting more observations from 19th century archives and re-analyzing them. Soon, I hope there will be enough information to convict or acquit Comet D/Swift."

This investigation may lead to others. "The space between Earth and Mars is probably criss-crossed by old debris streams," says Cooke. Wiegert's methods can be used to find some of them, "so the next meteor storm won't be such a surprise."

For more information:

NSSDC - Mariner 4
http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1964-077A

Smithsonian/NASA Astrophysics Data System (ADS) - 'So Much for Fame!': The Story of Lewis Swift
http://adsabs.harvard.edu//full/seri/QJRAS/0037//0000683.000.html