Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Small collisions make big impact on Mercury's thin atmosphere

02.10.2017

Mercury, our smallest planetary neighbor, has very little to call an atmosphere, but it does have a strange weather pattern: morning micro-meteor showers.

Recent modeling along with previously published results from NASA's MESSENGER spacecraft -- short for Mercury Surface, Space Environment, Geochemistry and Ranging, a mission that observed Mercury from 2011 to 2015 -- has shed new light on how certain types of comets influence the lopsided bombardment of Mercury's surface by tiny dust particles called micrometeoroids. This study also gave new insight into how these micrometeoroid showers can shape Mercury's very thin atmosphere, called an exosphere.


Scientists used models along with earlier findings from the MESSENGER mission to shed light on how certain types of comets influence the micrometeoroids that preferentially impact Mercury on the dawn side of the planet. Here, data from the Mercury Atmosphere and Surface Composition Spectrometer, or MASCS, instrument is overlain on the mosaic from the Mercury Dual Imaging System, or MDIS.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The research, led by Petr Pokorný, Menelaos Sarantos and Diego Janches of NASA's Goddard Space Flight Center in Greenbelt, Maryland, simulated the variations in meteoroid impacts, revealing surprising patterns in the time of day impacts occur. These findings were reported in the Astrophysical Journal Letters on June 19, 2017.

"Observations by MESSENGER indicated that dust must predominantly arrive at Mercury from specific directions, so we set out to prove this with models," Pokorný said. This is the first such simulation of meteoroid impacts on Mercury. "We simulated meteoroids in the solar system, particularly those originating from comets, and let them evolve over time."

Earlier findings based on data from MESSENGER's Ultraviolet and Visible Spectrometer revealed the effect of meteoroid impacts on Mercury's surface throughout the planet's day. The presence of magnesium and calcium in the exosphere is higher at Mercury's dawn -- indicating that meteoroid impacts are more frequent on whatever part of the planet is experiencing dawn at a given time.

This dawn-dusk asymmetry is created by a combination of Mercury's long day, in comparison to its year, and the fact that many meteroids in the solar system travel around the Sun in the direction opposite the planets. Because Mercury rotates so slowly -- once every 58 Earth days, compared to a Mercury year, a complete trip around the Sun, lasting only 88 Earth days -- the part of the planet at dawn spends a disproportionately long time in the path of one of the solar system's primary populations of micrometeoroids.

This population, called retrograde meteoroids, orbits the Sun in the direction opposite the planets and comprises pieces from disintegrated long-period comets. These retrograde meteroids are traveling against the flow of planetary traffic in our solar system, so their collisions with planets -- Mercury, in this case -- hit much harder than if they were traveling in the same direction.

These harder collisions helped the team further key in on the source of the micrometeoroids pummeling Mercury's surface. Meteroids that originally came from asteroids wouldn't be moving fast enough to create the observed impacts. Only meteoroids created from two certain types of comets -- Jupiter-family and Halley-type -- had the speed necessary to match the obseravations.

"The velocity of cometary meteoroids, like Halley-type, can exceed 224,000 miles per hour," Pokorný said. "Meteoroids from asteroids only impact Mercury at a fraction of that speed."

Jupiter-family comets, which are primarly influenced by our largest planet's gravity, have a relatively short orbit of less than 20 years. These comets are thought to be small pieces of objects originating in the Kuiper Belt, where Pluto orbits. The other contributor, Halley-type comets, have a longer orbit lasting upwards of 200 years. They come from the Oort Cloud, the most distant objects of our solar system -- more than a thousand times farther from the Sun than Earth.

The orbital distributions of both types of comets make them ideal candidates to produce the tiny meteoroids that influence Mercury's exosphere.

Pokorný and his team hope that their initial findings will improve our understanding of the rate at which comet-based micrometeoroids impact Mercury, further improving the accuracy of models of Mercury and its exosphere.

Sarah Frazier | EurekAlert!

More articles from Physics and Astronomy:

nachricht New manifestation of magnetic monopoles discovered
08.12.2017 | Institute of Science and Technology Austria

nachricht NASA's SuperTIGER balloon flies again to study heavy cosmic particles
07.12.2017 | NASA/Goddard Space Flight Center

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: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

Im Focus: Virtual Reality for Bacteria

An interdisciplinary group of researchers interfaced individual bacteria with a computer to build a hybrid bio-digital circuit - Study published in Nature Communications

Scientists at the Institute of Science and Technology Austria (IST Austria) have managed to control the behavior of individual bacteria by connecting them to a...

Im Focus: A space-time sensor for light-matter interactions

Physicists in the Laboratory for Attosecond Physics (run jointly by LMU Munich and the Max Planck Institute for Quantum Optics) have developed an attosecond electron microscope that allows them to visualize the dispersion of light in time and space, and observe the motions of electrons in atoms.

The most basic of all physical interactions in nature is that between light and matter. This interaction takes place in attosecond times (i.e. billionths of a...

Im Focus: A transistor of graphene nanoribbons

Transistors based on carbon nanostructures: what sounds like a futuristic dream could be reality in just a few years' time. An international research team working with Empa has now succeeded in producing nanotransistors from graphene ribbons that are only a few atoms wide, as reported in the current issue of the trade journal "Nature Communications."

Graphene ribbons that are only a few atoms wide, so-called graphene nanoribbons, have special electrical properties that make them promising candidates for the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

Blockchain is becoming more important in the energy market

05.12.2017 | Event News

 
Latest News

Making fuel out of thick air

08.12.2017 | Life Sciences

Rules for superconductivity mirrored in 'excitonic insulator'

08.12.2017 | Information Technology

Smartphone case offers blood glucose monitoring on the go

08.12.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>