Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UA Scientists Find Asteroids Are Missing, and Possibly Why

27.02.2009
University of Arizona scientists have uncovered a curious case of missing asteroids.

The main asteroid belt is a zone containing millions of rocky objects between the orbits of Mars and Jupiter. The scientists find that there ought to be more asteroids there than researchers observe. The missing asteroids may be evidence of an event that took place about 4 billion years ago, when the solar system's giant planets migrated to their present locations.

UA planetary sciences graduate student David A. Minton and UA planetary sciences professor Renu Malhotra say missing asteroids is an important piece of evidence to support an idea that the early solar system underwent a violent episode of giant planet migration that might possibly be responsible for a heavy asteroidal bombardment of the inner planets.

The scientists are reporting on their research in an article, "A record of planet migration in the Main Asteroid Belt," in the Feb. 26 issue of Nature.

Minton and Malhotra began by looking at the distribution of asteroids in the main asteroid belt. Astronomers first discovered a series of gaps in the asteroid belt, now called the Kirkwood gaps, back in the 1860s when only a handful of asteroids were known. The gaps occur at distinct regions of the asteroid belt where Jupiter's and Saturn's gravity strongly perturbs and ejects asteroids. The present-day orbits of Jupiter and Saturn explain why these unstable regions are devoid of asteroids.

"What we wanted to know was, how much of the structure of the asteroid belt could be explained simply by the gravitational effects of the giant planets, as are the Kirkwood gaps," Minton said.

Minton and Malhotra looked at the distribution of all asteroids with diameters greater than 50 kilometers, or about 30 miles. All asteroids of this size have been found, giving the UA researchers an observationally complete set for their study. Also, almost all asteroids this large have remained intact since the asteroid belt formed more than 4 billion years ago, a time record spanning all but the very beginning of solar system history.

"We ran massive sets of simulations with computer planets where we filled up the asteroid belt region with a uniform distribution of computer asteroids," Minton said. The scientists then had the computers simulate the billions of years of solar system history.

Their simulations ultimately ended with far more asteroids remaining than are actually observed in the asteroid belt. When the simulated asteroid belt was compared with the actual asteroid belt, they discovered a peculiar pattern in the differences. The simulated asteroid belt matched the real asteroid belt quite well on the sunward-facing sides of the Kirkwood gaps, but the real asteroid belt seemed to be depleted in asteroids on the Jupiter-facing sides.

"Then we simulated the migration of the giant planets," Minton said. "The perturbing effects of the migrating planets sculpted our simulated asteroid belt. After the migration was over, our simulated asteroid belt looked much more like the observed asteroid belt."

The UA scientists' research was funded by NASA and by the National Science Foundation.

"Our interpretation is that as Jupiter and Saturn migrated, their orbital resonances swept through the asteroid belt, ejecting many more asteroids than is possible with the planets in their current orbits," Malhotra said. "And the particular pattern of missing asteroids is characteristic of the pattern of Jupiter's and Saturn's migration."

"Our work explains why there are fewer asteroids on the Jupiter-facing side of the Kirkwood gaps compared to the sun-facing side," Minton said. "The patterns of depletion are like the footprints of wandering giant planets preserved in the asteroid belt."

Their results corroborate other lines of evidence indicating that the giant planets ? Jupiter, Saturn, Uranus and Neptune ? formed in a more tightly compacted configuration, and then Jupiter moved slightly closer to the sun, while the other giant planets moved farther apart from each other and farther away from the sun.

Minton and Malhotra say that their result has implications for how far and how fast the planets migrated early in solar system history, and the possibility that planet migration perturbed asteroids that may have contributed to a heavy bombardment of the inner solar system.

"Our result doesn't directly answer the question of whether the timing of this can be tied to inner solar system heavy bombardment ? that's open for debate," Minton said. "But what it does say is that there was an event that destabilized asteroids over a relatively short period of time.

"All the asteroids being kicked out of the asteroid belt had to go somewhere,"
he added. "The implication of this is that when all those asteroids were getting kicked out of the main belt, they could have become projectiles impacting the Earth and the moon, Mars, Venus and Mercury."
SCIENCE CONTACTS:
David A. Minton (520-621-7274; daminton@lpl.arizona.edu) Renu Malhotra (520-626-5899; renu@lpl.arizona.edu)

Lori Stiles | University of Arizona
Further information:
http://www.arizona.edu

More articles from Physics and Astronomy:

nachricht From rocks in Colorado, evidence of a 'chaotic solar system'
23.02.2017 | University of Wisconsin-Madison

nachricht Prediction: More gas-giants will be found orbiting Sun-like stars
22.02.2017 | Carnegie Institution for Science

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

From rocks in Colorado, evidence of a 'chaotic solar system'

23.02.2017 | Physics and Astronomy

'Quartz' crystals at the Earth's core power its magnetic field

23.02.2017 | Earth Sciences

Antimicrobial substances identified in Komodo dragon blood

23.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>