Canadian meteorite's roof crash leads to research on space rock orbits and building strikes

Scientists are on the hunt for the origin story of a meteorite that smashed through the roof into a bedroom in Canada on Oct. 3.

The "fall" of a space rock attracted an unusual amount of media attention after ending up on a pillow next to the face of resident Ruth Hamilton, who had been sleeping in her Golden, British Columbia home for several hours before her dog heard a crash on the roof around 11:30 p.m. local time (2:30 a.m. EDT or 0630 GMT Oct. 4.)

"The next thing was just a huge explosion and debris all over my face," Hamilton said in an interview with the Canadian Broadcasting Corp. (CBC), a national news service, on Oct. 12. Minutes later, a shocked Hamilton — while on the phone with 911 — recovered a 2.9 pound (1.3 kg) charcoal-grey rock from her pillowcase. A police investigation quickly ruled out construction from a nearby company when the workers on site reported a bright light in the sky and sonic booms, Hamilton told Victoria News.

Related: How often do meteorites hit the Earth?

That meteorite is now in the hands of scientists, who will spend several months piecing together the wider implications of the rock's history, such as what its composition is, what parent body it may have come from and what its orbit was in space. The meteorite may also add to a small but growing amount of information available concerning space-rock strikes on buildings.

Ontario's Western University (in central Canada) and Alberta's University of Calgary (in the province just east of B.C.) are asking the public to help search for fragments and to submit video footage to gather more information. 

This map from Western shows the likely impact sites of meteorites and the size of space rocks that could potentially be found there. Peter Brown, a prominent meteorite astronomer at Western University urged the public to prioritize looking for regions where smaller rocks might have fallen, as there are likely dozens available to find.

"You're looking for dark rocks on the outside that are heavier than typical rock, with a higher bulk density than your typical surface rock, and lightly attracted to a magnet," Brown told Space.com. 

"You can use that map," he added, "and as you go further north and into the east you're looking at smaller and smaller objects ... so that's something you want to keep in mind. People often will want to go look at the areas where the biggest fragments came down, but there's very few of those. In fact, it's possible all of the [bigger] ones that fell have been recovered."

So far, there are a few other pieces of evidence flowing in. A team led by Alan Hildebrand, a planetary scientist at the University of Calgary, recovered a second meteorite, roughly 0.7 kilograms (1.5 pounds), on a residential roadside near Edelweiss; the town is roughly a five-minute drive northwest of Golden. 

Meanwhile, the American Meteor Society has 30 reports (and a single video) of the fireball in a cluster of states and provinces stretching across the United States-Canada border, in Washington State, Idaho, British Columbia and Alberta.

Ongoing analysis

Figuring out more about the meteorite will take some time. One of the first things we will learn will be the composition of the meteorite. Based on its appearance, Brown said he can say it's an "ordinary chondrite," a very carbon-rich type of meteorite. But what type of chondrite can only be determined in the lab. 

Western paleogeographer Phil McCausland will likely perform a standard set of measurements on the meteorite such as microprobe analysis for major elements, or X-ray fluorescence to determine the minerals and major elements, all of which will assist with the categorization. Results should be available within a few weeks, if not sooner.

In the minutes before Brown's Space.com interview, he was examining the air waves the meteorite produced from two infrasound stations in Manitoba and in the United States. "That will give us an independent handle on the energy and hence, the mass" of the body that hit Earth's atmosphere, Brown said. The upper estimate of its mass is roughly 220 pounds (100 kg), but that measurement has considerable uncertainty right now.

Western has also received new video from amateur astronomers but hasn't yet secured permission from submitters to release footage to media. "We're hoping that the camera data will be able to give us a path and an orbit" for the object that hit the atmosphere, Brown said. Eventually, Brown said his team wants to learn what orbit it had in space and any possible parent bodies, although again that investigation will take weeks at the least.

Another point of interest — more on the statistical side — is the fact that the meteorite hit a building. Brown said the research shows about half of meteorite falls are recovered because they hit "structures or things that people interact with, like cars or driveways. It doesn't mean that's super common," he continued, "but it just means the meteorites we recover, often the reason we recovered is because somebody comes into contact with it."

There is little literature available about meteorite strikes on buildings, although Western did produce a poster at a 2017 International Academy of Astronautics conference in Tokyo focused on planetary defense, using the peer-reviewed information that was available at the time. The poster was led by William Cooke, who is today lead of NASA's Meteoroid Environments Office.

"A fragment hits a structure ... somewhere on the order of about half a dozen times per year globally," Brown said, based on the research the science team pulled up for the poster, a copy of which he provided to Space.com. "In North America, there's a building hit every three to five years."

There's a one-in-10 chance that somewhere in the world, a bed will get hit by meteorite due to simple math: About one meteorite is reported hitting a bed every decade. "In the last 50 years, there have been about five or six beds that have been hit by meteorites ... and any one person's bed [individually] has about a million-to-one chance of being hit by a meteorite," Brown said.

As for injuries, there has only been two ever reported. One was that of Ann Hodges in Sylacauga, Alabama, who received a large bruise on her side after a meteorite fell into her home on Nov. 30, 1954, bouncing off a radio console on the way down. This meteorite was the size of a softball with a mass of about 8.5 pounds (3.8 kg), or roughly seven to eight times the mass of the Golden meteorite.

The other injury report was a 1992 Mbale, Uganda meteorite fall in which a much smaller (only 4 gram) meteorite struck a young boy, according to the poster. The extent of the boy's injuries was not revealed, although the poster said neither the 1954 or 1992 incidents was fatal.

"The statistics for [injuries] are such that we expect it'll be hundreds of years, normally, between people being hurt and hundreds — even thousands — of years for someone to actually be hit by a meteorite big enough to kill them," Brown said. 

He cautioned that the upper estimates on injuries are "orders of magnitude" uncertain due to the small number of data points available in the statistics. "We have a better sense of small meteorites hitting a structure that might cause something that would be noticeable damage," he added. "You're talking tens of structures per year globally. It's quite a lot."

Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook.