Perseid meteor shower: August 2010 marks more than just a show
When the Perseid meteor shower peaks in the wee hours of an August Friday morning, Peter Brown & Co. will be ready.
No lawn chairs and hot-chocolate-filled thermoses here to keep meteor-shower observers happy.
Instead, Dr. Brown's team is using a new optical device it's developed for tracking meteors with unprecedented detail, pinpointing them at each spot along their paths through the sky to within about 30 feet.
From the glow of a meteor, the scientists aim to gather information on the chemistry taking place on its surface – reactions energized by the enormous heat that builds on the object as it collides with Earth's atmosphere.
Welcome to the world of meteor science – alive and well in Europe and Canada and in the midst of a renaissance in the United States after nearly two decades of neglect.
Much of the interest revolves around a need for improved predictions to reduce risks to spacecraft and astronauts on orbit.
But the study of meteors also is helping astronomers answer questions about our solar system, as well as potentially providing a new window on planet formation around other stars.
"Meteor research is a very interdisciplinary area" these days, says Brown, a physics professor and meteor maven at the University of Western Ontario in London, Ontario.
Meteors as cosmic bread crumbs
Meteors may be prime vehicles for delivering some of the organic molecules involved in the emergence of life on Earth. They have become cosmic bread crumbs leading back to the discovery of new sources for meteor shows, beyond the occasional passage of active comets. And some may be direct messengers from nearby stars hosting planets or a dusty disk from which planets are forming.
Spacecraft have detected tiny grains of interstellar dust as the spacecraft and dust flit through the solar system. But about a decade ago, researchers led by New Zealand astronomer Jack Baggaley, at the University of Canterbury in Christchurch, reported the radar detection of meteoroids entering Earth's atmosphere from beyond the solar system. Then the team traced the meteoroids to an interstellar dust streamer coming from Beta Pictoris, a star some 63 light-years away that has planets forming from a disk of dust that surrounds it.
The detection remains unconfirmed and thus contentious, Brown cautions. But if meteoroids of sufficient size do strike Earth's atmosphere and their appearance could be predicted, scientists could plan campaigns to gather spectral information from the light the meteors emit.
"It would be a new way of probing young stellar systems and newly forming planetary systems" that appear close to the solar system, Brown says.
Which puts a premium on work researchers are doing to confirm and identify the sources of some 364 meteor showers listed with the International Astronomical Union (IAU), the keeper of such information.
Charting showers
So far, 60 showers have been confirmed as each coming from a unique source, according to Peter Jenniskens, a meteor specialist at the SETI Institute in Mountain View, Calif., who heads an IAU committee tasked with naming meteor showers.
One result of this kind of work: confirming that some of the near-Earth objects astronomers are tracking for any collision risk they may present to Earth are in fact dead comets, not asteroids.
For instance, in 2003, Dr. Jenniskens and colleagues associated January's Quadrantid meteor shower with a near-Earth object discovered that year, 2003 EH1. It's thought to be a dead comet, which sheds material when portions of the loosely bound material just collapse into dust. Up to that time, scientists had associated the shower with an active comet, 96P/Machholz 1.
"It turns out that a lot of these are responsible for our meteor showers," Jenniskens says, referring to dead comets whose trips around the sun don't take them much farther away from the sun than Jupiter.
Indeed, the device that Brown's team is developing could improve scientists' ability to trace meteor showers to their sources. Its ability to track a meteor's travel across the sky with high precision will allow modelers to better determine the orbit of the dust trail it came from. That orbit can then be matched with the orbits of stony litterbugs that shed the dust.
Predicting future showers
This should improve predictions of future meteor showers.
Interest in meteors also has grown because of their potential astrobiological role, Brown adds. Direct impacts by comets and asteroids have long been leading candidates for bringing the chemical precursors for organic life to Earth's young surface. But meteors also could have played a considerable role.
These smaller objects could well be delivering organic molecules to Earth with properties and in combinations forged in the heat of a meteoroid's entry into the atmosphere.
That heating "produces a complex chemical cauldron of molecules that can be broken apart and then reassembled as things cool off," Brown says. "Could meteors have played a large role in the biological seeding and development of the Earth? Increasingly, a lot of people think that's quite plausible."
