Scientists Trying to Devise a Way to Trap Cosmic Dust
How do you catch something that is moving 10 times faster than a speeding bullet, vaporizes upon striking anything and requires a high-powered lens to be seen?
The secret, scientists say, is in measuring the speed and direction in which these “somethings” are traveling. But when they happen to be cosmic dust--particles that may hold clues about the origin and evolution of the solar system--catching them can pose a dilemma.
“You have to be able to find them,” said Joel Williams, who is part of a Los Alamos National Laboratory group in New Mexico that is evaluating cosmic dust catchers for the National Aeronautics and Space Administration.
Cosmic dust, Williams underscored, can be elusive.
Scientists believe the dust is valuable for what it may tell of the heavens as well as for its possible biological implications, Williams said.
Perhaps bits of dust that have streamed in from the outer reaches of the universe can reveal something about the chemistry of deep space. Maybe the dust contains precursors to amino acids, the chemical building blocks of proteins that make up all living matter on Earth.
Some scientists have hypothesized that asteroids or comets laden with the primordial chemicals of life bombarded early Earth, providing the necessary raw materials that set the stage for the evolution of plants and animals.
Challenge at Hand
But the swirling aggregates of interplanetary dust have been well known to astronomers for decades. The quest now is how to trap the particles.
Such debris, often part of great bands of dust, is found throughout the solar system and scatters light from the rising and setting sun when viewed from areas far away from city lights, giving the effect of a soft solar glow that expands the horizon.
While scientists believe the dust particles to be among the most abundant cosmic materials in the solar system, orbiting in bands between the planets and around the sun, they have had difficulty trying to catch it.
“First you have to record their direction and velocity. Then you must stop them with minimum damage,” Williams said of the cosmic specks, some measuring less than one-thousandth of an inch across, that have broken from comets, asteroids and even meteors farther away in space.
The cosmic dust sprinkled through Earth’s stratosphere, extending up to 30 miles above the planet’s surface, is puzzling scientists who are trying to figure out if the dust is a product of asteroids or comets. Studies tentatively suggest much of it may have showered down from the speeding Halley’s Comet when it made its visit to the solar system in 1986.
Williams said NASA officials hope one day to have a dust-catching wing aboard the proposed space station Freedom, from which collectors might retrieve micrometeorites, bits of comet and asteroid remains.
Los Alamos scientists are envisioning a cosmic dust catcher that would be about a foot thick and measure 10 feet by 10 feet.
So far, proposals for the unit indicate the catcher would have to remain in place for long periods, possibly up to a year at a time, because “hits” from cosmic dust would be very rare.
Moreover, dust catching materials aboard the station would have to be manufactured to provide a cushion for the specks, something akin to “catching a ball with a pillow,” Williams said.
For years scientists believed most interplanetary dust came from comets whizzing past the sun, leaving traces of their existence behind.
But a growing body of evidence from the Infrared Astronomical Satellite (IRAS) indicates a large proportion of the dust may have emanated not from comets but from asteroids.
Cornell University researchers Stanley Dermott and Philip Nicholson reported at a recent meeting of the International Astronomical Union that bands of dust orbiting the sun may have come from two specific families of asteroids.
Dermott and Nicholson conducted a computer simulation of particles orbiting the sun and compared their work to data beamed back from IRAS. They concluded that dust, which is under both planetary and sunlight influences, emanated from the Themis and Eos asteroid families.
An asteroid family forms when two large bodies collide, annihilating themselves but leaving behind a smaller group of asteroids in roughly the same orbits.
The Cornell researchers hypothesize current asteroid families developed billions of years ago. But because interplanetary dust remains in orbiting bands for approximately 10,000 years, bands now under study probably are made up of debris that has rained down from the asteroid belt.
Asteroids, also known as planetoids, are the irregularly shaped bodies made up of nickel, iron and other materials that are believed to be fragments of planets or substances that did not condense into planets eons ago.
They orbit the sun mostly at a point in space between the orbits of Mars and Jupiter.