Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The Anatomy of an Asteroid

05.02.2014
ESO’s New Technology Telescope (NTT) has been used to find the first evidence that asteroids can have a highly varied internal structure.

By making exquisitely precise measurements astronomers have found that different parts of the asteroid Itokawa have different densities. As well as revealing secrets about the asteroid’s formation, finding out what lies below the surface of asteroids may also shed light on what happens when bodies collide in the Solar System, and provide clues about how planets form.


A schematic view of the strange peanut-shaped asteroid Itokawa.

By making exquisitely precise timing measurements using ESO’s New Technology Telescope, and combining them with a model of the asteroid's surface topography, a team of astronomers has found that different parts of this asteroid have different densities. As well as revealing secrets about the asteroid’s formation, finding out what lies below the surface of asteroids may also shed light on what happens when bodies collide in the Solar System, and provide clues about how planets form. The shape model used for this view is based on the images collected by JAXA's Hayabusa spacecraft.

Credit:
ESO. Acknowledgement: JAXA

Using very precise ground-based observations, Stephen Lowry (University of Kent, UK) and colleagues have measured the speed at which the near-Earth asteroid (25143) Itokawa spins and how that spin rate is changing over time. They have combined these delicate observations with new theoretical work on how asteroids radiate heat.

This small asteroid is an intriguing subject as it has a strange peanut shape, as revealed by the Japanese spacecraft Hayabusa in 2005. To probe its internal structure, Lowry’s team used images gathered from 2001 to 2013, by ESO’s New Technology Telescope (NTT) at the La Silla Observatory in Chile among others [1], to measure its brightness variation as it rotates.

This timing data was then used to deduce the asteroid’s spin period very accurately and determine how it is changing over time. When combined with knowledge of the asteroid’s shape this allowed them to explore its interior — revealing the complexity within its core for the first time [2].

“This is the first time we have ever been able to to determine what it is like inside an asteroid,” explains Lowry. “We can see that Itokawa has a highly varied structure — this finding is a significant step forward in our understanding of rocky bodies in the Solar System.”

The spin of an asteroid and other small bodies in space can be affected by sunlight. This phenomenon, known as the Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) effect, occurs when absorbed light from the Sun is re-emitted from the surface of the object in the form of heat. When the shape of the asteroid is very irregular the heat is not radiated evenly and this creates a tiny, but continuous, torque on the body and changes its spin rate [3], [4].

Lowry’s team measured that the YORP effect was slowly accelerating the rate at which Itokawa spins. The change in rotation period is tiny — a mere 0.045 seconds per year. But this was very different from what was expected and can only be explained if the two parts of the asteroid’s peanut shape have different densities.

This is the first time that astronomers have found evidence for the highly varied internal structure of asteroids. Up until now, the properties of asteroid interiors could only be inferred using rough overall density measurements. This rare glimpse into the diverse innards of Itokawa has led to much speculation regarding its formation. One possibility is that it formed from the two components of a double asteroid after they bumped together and merged.

Lowry added, “Finding that asteroids don’t have homogeneous interiors has far-reaching implications, particularly for models of binary asteroid formation. It could also help with work on reducing the danger of asteroid collisions with Earth, or with plans for future trips to these rocky bodies.”

This new ability to probe the interior of an asteroid is a significant step forward, and may help to unlock many secrets of these mysterious objects.

Notes

[1] As well as the NTT, brightness measurements from the following telescopes were also used in this work: Palomar Observatory 60-inch Telescope (California, USA), Table Mountain Observatory (California, USA), Steward Observatory 60-inch Telescope (Arizona, USA), Steward Observatory 90-inch Bok Telescope (Arizona, USA), 2-metre Liverpool Telescope (La Palma, Spain), 2.5-metre Isaac Newton Telescope (La Palma, Spain) and the Palomar Observatory 5-metre Hale Telescope (California, USA).

[2] The density of the interior was found to vary from 1.75 to 2.85 grammes per cubic centimetre. The two densities refer to Itokawa’s two distinct parts.

[3] As a simple and rough analogy for the YORP effect, if one were to shine an intense enough light beam on a propeller it would slowly start spinning due to a similar effect.

[4] Lowry and colleagues were the first to observe the effect in action on a small asteroid known as 2000 PH5 (now known as 54509 YORP, see eso0711). ESO facilities also played a crucial role in this earlier study.

More Information

This research was presented in a paper “The Internal Structure of Asteroid (25143) Itokawa as Revealed by Detection of YORP Spin-up”, by Lowry et al., to appear in the journal Astronomy & Astrophysics.

The team is composed of S.C Lowry (Centre for Astrophysics and Planetary Science, School of Physical Sciences (SEPnet), The University of Kent, UK), P.R. Weissman (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA [JPL]), S.R. Duddy (Centre for Astrophysics and Planetary Science, School of Physical Sciences (SEPnet), The University of Kent, UK), B.Rozitis (Planetary and Space Sciences, Department of Physical Sciences, The Open University, Milton Keynes, UK), A. Fitzsimmons (Astrophysics Research Centre, University Belfast, Belfast, UK), S.F. Green (Planetary and Space Sciences, Department of Physical Sciences, The Open University, Milton Keynes, UK), M.D. Hicks (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA), C. Snodgrass (Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany), S.D. Wolters (JPL), S.R. Chesley (JPL), J. Pittichová (JPL) and P. van Oers (Isaac Newton Group of Telescopes, Canary Islands, Spain).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries.

ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Contacts
Stephen C. Lowry
The University of Kent
Canterbury, United Kingdom
Tel: +44 1227 823584
Email: s.c.lowry@kent.ac.uk
Richard Hook
ESO, Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
Katie Scoggins
Press Officer, Corporate Communications Office, University of Kent
Canterbury, United Kingdom
Tel: +44 1227 823581
Email: K.Scoggins@kent.ac.uk

Richard Hook | ESO-Media-Newsletter
Further information:
http://www.eso.org

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

NASA eyes Pineapple Express soaking California

24.02.2017 | Earth Sciences

New gene for atrazine resistance identified in waterhemp

24.02.2017 | Agricultural and Forestry Science

New Mechanisms of Gene Inactivation may prevent Aging and Cancer

24.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>