Researchers from Kobe University and the National Institute of Technology, Oshima College have conducted a detailed reanalysis of image data from Voyager 1, 2 and Galileo spacecraft in order to investigate the orientation and distribution of the ancient tectonic troughs found on Jupiters moon Ganymede.
They discovered that these troughs are concentrically distributed across almost the entire surface of the satellite. This global distribution indicates that these troughs may be actually part of one giant crater covering Ganymede.
Based on the results of a computer simulation conducted using the PC Cluster at the National Astronomical Observatory of Japan (NAOJ), it is speculated that this giant crater could have resulted from the impact of an asteroid with a radius of 150km. If so, the structure is the largest impact structure identified in the solar system so far.
The European Space Agencys JUICE (Jupiter Icy Moon Explorer) mission, which will be launched in 2022 and arrive in Jupiters system in 2029, aims to increase our knowledge regarding Jupiters satellites, including Ganymede. It is hoped that this exploration will confirm the results of this study and further advance our understanding of the formation and evolution of Jupiters satellites.
The research team consisted of Kobe University Graduate School of Sciences Assistant Professor HIRATA Naoyuki and Professor OHTSUKI Keiji (both of the Department of Planetology), and Associate Professor SUETSUGU Ryo of National Institute of Technology, Oshima College.
Images of Ganymedes surface taken by Voyager 2 (left) and Galileo (right). The Dark Terrain and Bright Terrain areas can be recognized, with concurrent furrows present in these Dark Terrains. (Image credit: NASA)
Main Points
Research Background
Both Voyager 1 and Voyager 2 have closely approached Ganymede in 1979 and 1980 respectively, taking detailed images of the surface. In addition, the Galileo spacecraft orbited Jupiter from 1995 to 2003, obtaining a large amount of Ganymede image data. Ganymede is the largest satellite in the solar system and is bigger than both Pluto and Mercury.
The formation and evolution of Jupiters moons including Ganymede is strongly connected to the formation and evolution of the Jupiter system, and by extension, of the solar system. Consequently, there are various ongoing and planned spacecraft missions to explore the satellite system, including NASAs JUNO mission that is ongoing, the Europa Clipper scheduled to perform a detailed investigation of Jupiters moon Europa in around 2030, and the aforementioned JUICE mission.
The study was conducted with the aims of clarifying one aspect of the formation and evolution of Jupiters satellites and of contributing towards these spacecraft missions. The group reanalyzed image data of Ganymede. In particular, the researchers focused on furrows (Figure 1), tectonic troughs that are believed to be the oldest surface features on the satellite. Therefore, the research group hypothesized that they could reconstruct the early history of Ganymede by analyzing these geological formations.
Research Findings
Ganymedes surface is categorized into areas of Dark Terrain and Bright Terrain. Dark Terrain is extremely old and has many remaining craters, as well as trough formations (Figure 1). Bright Terrain is comparatively recent, with hardly any craters. These two types of terrain are not coherently arranged and are randomly distributed over Ganymedes entirety. Furrows are believed to be Ganymedes oldest geological features because they are only found on Dark Terrain and many impact craters (*1) have been formed on top of them later on.
This study reanalyzed the distribution of these trough formations over Ganymedes entire surface, revealing for the first time that almost all of these furrows are concentrically aligned around a single point (Figure 2). The study showed that these furrows form giant, concentric rings over the entire satellite. From this, it can be assumed that there was a giant multiring impact crater which covered the entire surface of Ganymede before the formation of the Bright Terrain areas.
A similar ring structure known as the Valhalla Crater remains on the surface of Callisto, another satellite of Jupiter. Until now, the Valhalla Crater has been the largest identified multiring crater in the solar system, with a radius of approximately 1900km. However, the multiring crater on Ganymede has a radial extent of 7800km measured along the satellites surface.
The research team conducted a simulation to estimate the scale of the impact that formed this giant crater. This was carried out using the PC Cluster at the National Astronomical Observatory of Japan (NAOJ). The results indicated that an asteroid with a radius of 150km impacting Ganymede at a speed of 20km/s would be sufficient to form the observed structures on the satellites surface (Figure 3). It is believed that such an impact occurred around 40 billion years ago.
Further Developments
The discovery that the aftermath of a large-scale impact remains on Ganymedes surface is greatly significant in terms of the satellites formation process and evolution. For example, Jupiters satellite Callisto is around the same size as Ganymede, however it is believed that it doesnt have an internal structure composed of differentiated layers. On the other hand, Ganymede is thought to be composed of a differentiated layer structure consisting of rock, iron and ice. An enormous amount of heat is necessary to form these differentiated layers. It is possible that the aforementioned large-scale impact could have been the source of this heat.
This studys discovery will also have substantial significance for the Ganymede exploration programs scheduled in the coming decades. The image data from both Voyager and Galileo missions only provide partial views of the satellites surface. It is hoped that future explorations will be able to confirm or test this studys results by conducting detailed investigations into the multiring formations and whether or not there are any other remains of large-scale impacts. Hopefully, this will result in a deeper understanding of the origins and evolution of Ganymede as well as Jupiters other moons.
Kobe University
Header Image Credit : Public Domain
Continue reading here:
Ring-like Structure on Ganymede May Have Been Caused by a Violent Impact - HeritageDaily
- Lilah Brown's Planets, Part II (or, Season II preview) - November 8th, 2009 [November 8th, 2009]
- Snow White needs a bailout - November 8th, 2009 [November 8th, 2009]
- To the moon - November 8th, 2009 [November 8th, 2009]
- S/1 90482 (2005) needs your help - November 8th, 2009 [November 8th, 2009]
- We'll always have Regulus - November 8th, 2009 [November 8th, 2009]
- Orcus Porcus - November 8th, 2009 [November 8th, 2009]
- Kant's Crowded Universe - November 8th, 2009 [November 8th, 2009]
- Look up! - November 8th, 2009 [November 8th, 2009]
- Baby Pictures - November 8th, 2009 [November 8th, 2009]
- Encore: Yelping at Saints - November 8th, 2009 [November 8th, 2009]
- Godspeed - November 8th, 2009 [November 8th, 2009]
- Heavens above! - November 8th, 2009 [November 8th, 2009]
- Homeward bound - November 8th, 2009 [November 8th, 2009]
- Sony Pictures and the end of the world - November 8th, 2009 [November 8th, 2009]
- Thank you from the future - November 8th, 2009 [November 8th, 2009]
- Lunar dreams - November 8th, 2009 [November 8th, 2009]
- The first of the Pluto books! - November 8th, 2009 [November 8th, 2009]
- Don't try to blame it on Rio - November 8th, 2009 [November 8th, 2009]
- Rio roundup - November 8th, 2009 [November 8th, 2009]
- The long road to a Titan storm - November 8th, 2009 [November 8th, 2009]
- Planetary Placemats - November 8th, 2009 [November 8th, 2009]
- Fog! Titan! Titan Fog! (and a peer review experiment) - November 8th, 2009 [November 8th, 2009]
- Millard Canyon Memories - November 8th, 2009 [November 8th, 2009]
- The problem with science - November 8th, 2009 [November 8th, 2009]
- P.S. on the problem with science - November 8th, 2009 [November 8th, 2009]
- How Big is 10 TB? - November 8th, 2009 [November 8th, 2009]
- Showing You Your Servers - November 8th, 2009 [November 8th, 2009]
- Pick Your Partnership: Referral Partners, Resellers and Affiliates - November 8th, 2009 [November 8th, 2009]
- Server Form Factors: Towers v. Rack-Mounts - November 8th, 2009 [November 8th, 2009]
- Lights-Out in the Data Centers - November 8th, 2009 [November 8th, 2009]
- Disruptive Technologies: Virtualization and The Cloud - November 8th, 2009 [November 8th, 2009]
- Know Thy Backups – Part I - November 8th, 2009 [November 8th, 2009]
- Know Thy Backups – Part II - November 8th, 2009 [November 8th, 2009]
- Boo Bash 2009 – Desktop Costume Included! - November 8th, 2009 [November 8th, 2009]
- Why No One Will Talk About “Cloud Computing” in 10 Years - November 8th, 2009 [November 8th, 2009]
- The end of the fall - December 13th, 2009 [December 13th, 2009]
- We Love ‘Server Huggers’ - December 13th, 2009 [December 13th, 2009]
- All About the Cloud: An Interview with Dell’s Cloud Evangelist - December 13th, 2009 [December 13th, 2009]
- Happy Solstice - December 21st, 2009 [December 21st, 2009]
- A ghost of Christmas past - December 31st, 2009 [December 31st, 2009]
- Learning from a Blender - January 5th, 2010 [January 5th, 2010]
- Changing my world - January 6th, 2010 [January 6th, 2010]
- A Server. From Scratch. - January 7th, 2010 [January 7th, 2010]
- The Planet Sand Castle: Upgrade Your Sandbox - January 12th, 2010 [January 12th, 2010]
- Hosting for Haiti - January 20th, 2010 [January 20th, 2010]
- Redefining Value - January 26th, 2010 [January 26th, 2010]
- My Experience as a Newbie at The Planet - January 28th, 2010 [January 28th, 2010]
- Confessions of Another New Planeteer - February 1st, 2010 [February 1st, 2010]
- How I Learned to Stop Worrying and Love Permissions - February 11th, 2010 [February 11th, 2010]
- Where at The Planet is Rachel? - February 15th, 2010 [February 15th, 2010]
- The Planet Storage Cloud: FYI - February 19th, 2010 [February 19th, 2010]
- Meet us in March - February 25th, 2010 [February 25th, 2010]
- The Planet in “The Channel” - March 2nd, 2010 [March 2nd, 2010]
- The Planet Server Challenge - March 13th, 2010 [March 13th, 2010]
- The Definitive Guide to Finding The Planet at SXSW - March 13th, 2010 [March 13th, 2010]
- The SXSW Iron Geek Champion! - March 15th, 2010 [March 15th, 2010]
- Drinking from the Fire Hose - March 16th, 2010 [March 16th, 2010]
- The Fastest Hands at SXSW - March 17th, 2010 [March 17th, 2010]
- System.out.println(“Hello World!”); - March 22nd, 2010 [March 22nd, 2010]
- Westmere – Get it Here - March 23rd, 2010 [March 23rd, 2010]
- Orbit on Your iPhone: A Sign of Things to Come - March 24th, 2010 [March 24th, 2010]
- #ShowMeMyServer 2.0 - March 25th, 2010 [March 25th, 2010]
- Get to Know Your Visitors - March 30th, 2010 [March 30th, 2010]
- The Next Big Thing in Hosting: The Hostatulator - April 1st, 2010 [April 1st, 2010]
- Storage Cloud and the City - April 4th, 2010 [April 4th, 2010]
- American Heart – Why I Walk - April 7th, 2010 [April 7th, 2010]
- The Cake Shouldn’t Be a Lie - April 8th, 2010 [April 8th, 2010]
- April Showers Bring May Flowers - April 9th, 2010 [April 9th, 2010]
- First at The Planet: Nehalem EX 4-Socket Servers - April 15th, 2010 [April 15th, 2010]
- Intel Guest Blog: Xeon 5600 - April 16th, 2010 [April 16th, 2010]
- Inside the Office: A Birthday Surprise - April 18th, 2010 [April 18th, 2010]
- The Planet @ Cloud Expo East - April 19th, 2010 [April 19th, 2010]
- The Planet @ ad:tech SF - April 22nd, 2010 [April 22nd, 2010]
- ad:tech Server Challenge - April 22nd, 2010 [April 22nd, 2010]
- ad:tech Panel: Developing Communities Online - April 23rd, 2010 [April 23rd, 2010]
- The Planet @ Interop Las Vegas - April 27th, 2010 [April 27th, 2010]
- Overflowing With Value: 10TB is Back! - April 28th, 2010 [April 28th, 2010]
- The Cloud is NOT the Revolution - April 29th, 2010 [April 29th, 2010]
- The Importance of Orbit 2.0 - May 5th, 2010 [May 5th, 2010]
- The Planet @ Web 2.0 Expo - May 6th, 2010 [May 6th, 2010]