Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Large asteroid is two orbiting objects

24.10.2003


An asteroid that has eluded astronomers for decades turns out to be an unusual pair of objects traveling together in space, a UCLA planetary scientist and colleagues report.



The asteroid Hermes was rediscovered last week after being lost for 66 years. Now Jean-Luc Margot, a researcher in UCLA’s department of Earth and space sciences, has determined that the asteroid is, in fact, two objects orbiting each other. The two objects together would cover an area approximately the size of Disneyland.

Margot and colleagues are analyzing new radar measurements from the Arecibo Observatory, part of the National Astronomy and Ionosphere Center, which is operated by Cornell University under a cooperative agreement with the National Science Foundation. The researchers are scheduled to obtain additional measurements Oct. 25–26 from the observatory, located in Puerto Rico.


Hermes makes frequent close approaches to Earth, Venus and Mars, as well as Vesta, the third-largest asteroid in the main asteroid belt between Mars and Jupiter.

While several other asteroids have satellites, the other known binaries with trajectories that cross the orbit of the Earth consist of a large primary asteroid orbited by a much smaller one.

"Hermes is the first asteroid ever discovered in the near-Earth population where the two components are essentially equal in size," Margot said. "It’s a very unusual binary, a puzzle. It may have formed when it swung so close to a planet that it was ripped apart by gravitational forces, but we don’t know for sure. One of our goals is to learn more about the two components and how they rotate about each other in the hopes that we may be able to deduce how Hermes became a double asteroid.

"Because the components are close to each other, they raise appreciable tides in each other and each has slowed down the other’s spin significantly. They are now likely in a doubly synchronous state, where their spin period is equal to their orbital period. This means they constantly present the same face to each other, just like Pluto and its satellite Charon."

A fast-moving bright object was observed in 1937, named Hermes, and went undetected until last week, although it had revolved around the Sun almost 31 times since then, escaping notice, said Brian Marsden, of the Minor Planet Center in Cambridge, Mass.

On Oct. 15, Brian Skiff of the Lowell Observatory Near-Earth-Object Search sighted the mysterious object; Timothy Spahr at the Minor Planet Center identified similarities with the 1937 observations; and Steven Chesley and Paul Chodas at NASA’s Jet Propulsion Laboratory (JPL) linked the observations to Hermes.

The same day, Margot and his team proposed to observe the asteroid with the Arecibo Observatory’s high-powered radar system -- a proposal that was accepted within hours.

The goals of the proposal were to measure precisely the distance and velocity of this object, to improve the knowledge of its trajectory and help trace back its history, to characterize Hermes’ physical properties, and to search for satellites.

Margot and collaborators have been given five sessions at Arecibo and sessions at the Goldstone radar in California to observe Hermes. Due to the urgent nature of the proposal, Margot observed from his home computer while Mike Nolan, Victor Negron, Alice Hine and Don Campbell were at the Arecibo telescope.

Hermes gets as close as 378 000 miles from Earth -- which, in astronomical terms, is quite close, about 1.6 times the distance between Earth and the moon. Orbits can change appreciably over time due to gravitational influences of the planets, noted Mike Nolan, an Arecibo Observatory scientist and member of the team.

Hermes travels on an elliptical orbit and reaches deep into the inner solar system, crossing Venus’ orbit. The new research has made it possible to extend the time interval over which the trajectory can be computed reliably, said Jon Giorgini, a senior engineer at JPL and member of the team.

"As far as impact risk, there is no cause for worry in our lifetimes," Giorgini said. "Over hundreds of thousands, or millions of years, Hermes could impact the Earth, but only if it doesn’t hit Venus first."

Margot and colleagues described their observations and data in an International Astronomical Union Circular this week. Margot’s research is funded by NASA. His co-authors are Michael Nolan, Victor Negron, Alice Hine, Donald Campbell and Ellen Howell at the National Astronomy and Ionosphere Center; Lance Benner, Steven Ostro and Jon Giorgini at JPL; and Brian Marsden at the Minor Planet Center.

Stuart Wolpert | EurekAlert!
Further information:
http://www2.ess.ucla.edu/~jlmargot/NEAs/Hermes

More articles from Physics and Astronomy:

nachricht A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Quantum thermometer or optical refrigerator?
23.06.2017 | National Institute of Standards and Technology (NIST)

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>