Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Study Puts Solar Spin on Asteroids, their Moons & Earth Impacts

Asteroids with moons, which scientists call binary asteroids, are common in the solar system. A longstanding question has been how the majority of such moons are formed. In this week’s issue of the journal Nature, a trio of astronomers from Maryland and France say the surprising answer is sunlight, which can increase or decrease the spin rate of an asteroid.

Derek Richardson, of the University of Maryland, his former student Kevin Walsh, now Poincaré Fellow in the Planetology Group in the Cassiopée Laboratory of CNRS at the Cote d'Azur Observatory, France, and that group’s leader, co-author Patrick Michel outline a model showing that when solar energy “spins up” a “rubble pile” asteroid to a sufficiently fast rate, material is slung off from around the asteroid’s equator. This process also exposes fresh material at the poles of the asteroid.

If the spun off bits of asteroid rubble shed sufficient excess motion through collisions with each other, then the material coalesces into a satellite that continues to orbit its parent.

Because the team’s model closely matches observations from binary asteroids, it neatly fills in missing pieces to a solar system puzzle. And, it could have much more down-to-earth implications as well. The model gives information on the shapes and structure of near-Earth binary asteroids that could be vital should such a pair need to be deflected away from a collision course with Earth.

Finally, the authors say, these findings suggest that a sample return mission to such a binary asteroid could bring back exposed pristine material from the poles of the parent asteroid, providing a chance to probe the internal composition of an asteroid without having to dig into it.

Solar Spin Power
It’s estimated that about 15 per cent of near-Earth and main-belt asteroids with diameters less than 10 kilometers have satellites. Scientists have determined that these small binary asteroid pairs were not formed at the beginning of the solar system, indicating that some process still at work must have created them.

“It was at first thought the moons in these asteroid pairs probably formed through collisions and/or close encounters with planets,” said Richardson, an associate professor of astronomy at the University of Maryland. “However, it was found that these mechanisms could not account for the large number of binary asteroids present among near-Earth and inner main belt asteroids.”

Recent studies have outlined a thermal process – known as the YORP effect after the scientists (Yarkovsky, O’Keefe, Radzievskii, Paddack) who identified it – by which sunlight can speed up or slow down an asteroid’s spin. Widespread evidence of this mechanism can be seen in the “notable abundance of both fast and slow rotators among [near-Earth asteroids] and small main belt asteroids,” Walsh, Richardson and Michel write in the Nature paper.

The trio modeled different types of 'rubble pile' asteroids -- chunks of rock held together by gravity. This work, supported by the National Science Foundation and NASA, as well as the European Space Agency and the French National Planetology Program, is the first to show how the slow spinup of such asteroids leads over millions of years to mass loss that can form binaries.

“Our model almost exactly matches the observations of our test case, binary asteroid KW4, which was imaged incredibly well by the NSF-supported Arecibo radio telescope in Puerto Rico,” Walsh said.

Asteroid Deep Impacts
“Based on our findings, the YORP effect appears to be the key to the origin of a large fraction of observed binaries,” said Michel. “The implications are that binary asteroids are preferentially formed from aggregate objects [rubble piles], which agrees with the idea that such asteroids are quite porous. The porous nature of these asteroids has strong implications for defensive strategies if faced with an impact risk to Earth from such objects, because the energy required to deflect an asteroid depends sensitively on its internal structure,” he said.

Doublet craters formed by the nearly simultaneous impact of objects of comparable size can be found in a number of places on Earth, suggesting that binary asteroids have hit our planet in the past. Similar doublet craters also can be found on other planets.

The authors say that their current findings also suggest that a space mission to a binary asteroid could bring back material that might shed new light on the solar system’s early history. The oldest material in an asteroid should lie underneath its surface, explained Richardson, and the process of spinning off this surface material from the primary asteroid body to form its moon, or secondary body, should uncover the deeper older material.

“Thus a mission to collect and return a sample from the primary body of such a binary asteroid could give us information about the older, more pristine material inside an asteroid, just as the University of Maryland-led Deep Impact gave us information about the more pristine material inside a comet,” Richardson said.

Michel added, “Bringing back pristine material is the goal of our proposed Marco Polo mission, which is currently under study by the European Space Agency, in partnership with JAXA in Japan.”

Lee Tune | Newswise Science News
Further information:

More articles from Physics and Astronomy:

nachricht Sharpening the X-ray view of the nanocosm
23.03.2018 | Changchun Institute of Optics, Fine Mechanics and Physics

nachricht Drug or duplicate?
23.03.2018 | Fraunhofer-Institut für Angewandte Festkörperphysik IAF

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: Space observation with radar to secure Germany's space infrastructure

Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.

The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...

Im Focus: Researchers Discover New Anti-Cancer Protein

An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.

The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

New solar solutions for sustainable buildings and cities

23.03.2018 | Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

Latest News

For graphite pellets, just add elbow grease

23.03.2018 | Materials Sciences

Unique communication strategy discovered in stem cell pathway controlling plant growth

23.03.2018 | Agricultural and Forestry Science

Sharpening the X-ray view of the nanocosm

23.03.2018 | Physics and Astronomy

Science & Research
Overview of more VideoLinks >>>