Path: utzoo!news-server.csri.toronto.edu!rutgers!gatech!udel!wuarchive!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke From: baalke@mars.jpl.nasa.gov (Ron Baalke) Newsgroups: comp.graphics Subject: Magellan Images Keywords: Magellan, JPL Message-ID: <1991Mar13.213459.1452@jato.jpl.nasa.gov> Date: 13 Mar 91 21:34:59 GMT Sender: news@jato.jpl.nasa.gov Reply-To: baalke@mars.jpl.nasa.gov (Ron Baalke) Organization: Jet Propulsion Laboratory, Pasadena, CA. Lines: 94 Nntp-Posting-Host: mars.jpl.nasa.gov =================== MAGELLAN IMAGES March 13, 1991 =================== I've placed two more Magellan images in VICAR format and 11 in GIF format at the Ames SPACE archives, bringing the Magellan total to 14 VICAR images and 28 GIF images. They can be obtained via anonymous ftp from ames.arc.nasa.gov (128.102.18.3), and are in the pub/SPACE/VICAR and pub/SPACE/GIF directories, respectively. The two new VICAR files are called pancakes.img and bahet.img. All of the VICAR images have a corresponding caption files (with a .txt extension) which contains detailed descriptions of the image. Make sure you are in binary mode when transferring the image files, and in ASCII mode when transferring the text files. The two new caption files are appended to the end of this message. The VICAR images can be viewed on an IBM PC computer with the IMDISP program stored in a zip file called imdisp56.zip, located in the pub/SPACE/IMDISP directory. The VICAR format is the format used by the Image Processing Lab (MIPL) at JPL. Most of the VICAR images are in 1024x1024 pixel resolution and are 1MB in size. The pancakes.img image is the image showing the 7 pancake volcanoes. The pan10.img file that I had uploaded earlier shows 3 of the 7 volcanoes. I've converted all of the Magellan VICAR images into GIF format in 640x480 resolution. The new GIF files are: saca1.gif pancakes.gif saca2.gif pancake1.gif saca3.gif bahet.gif saca4.gif bahet1.gif saca5.gif bahet2.gif saca6.gif The saca GIFs were all derived from the original saca.img file which I placed at the Ames site earlier. The original file is quite large at 2.8 MB. This saca.img file had to be reduced by a factor of 4 in order for it to fit in the 640x480 GIF resolution. The six new saca GIF files are closeups of various parts of the saca.img with no detail loss. The pancakes.gif was converted from pancakes.img, with pancake1.gif zooming in on 4 of the volcanoes. Likewise, bahet.gif was converted from bahet.img, with bahet1.gif and bahet2.gif being subsections of bahet.img, showing it in greater detail. ============================================================================ PANCAKES.TXT (same as PAN10.TXT) This image of the eastern edge of Alpha Regio, 30 degrees south latitude, 11.8 east longitude, was acquired on November 7, 1990. It shows seven circular domical hills averaging 25 kilometers (15 miles) in diameter and maximum heights of 750 meters (2475 feet). These features can be interpreted as viscous or thick eruptions of lava coming from a vent on the relatively level ground allowing the lava to flow in an even lateral pattern. The concentric and radial fracture pattern on their surfaces suggests if they are extrusive that a chilled outer layer formed then further intrusion in the interior stretched the surface. The domes may be analogous to volcanic domes on Earth. An alternative interpretation is that the domes are the result of shallow intrusions up-doming the surface layers. If they are intrusive, then magma withdrawal near the end of the eruptions then produced the fractures. The bright margins possibly indicate the presence of rock debris or talus at the slopes of the domes. Fractures on the surrounding plains are both older and younger than the domical hills. Resolution of the Magellan data is about 120 meters (400 feet). ============================================================================ BAHET.TXT This mosaic of Magellan data in the Fortuna region of Venus, centered at 49 degrees north latitude, 2 degrees longitude, shows two coronae. Coronae are large circular or oval structures first identified in Soviet radar images of Venus. The structure on the left, Bahet Corona, is about 230 kilometers (138 miles) long and 150 kilometers (90 miles) across. A portion of Onatah Corona, over 350 kilometers (210 miles) in diameter, can be seen on the right of the mosaic. Both features are surrounded by a ring of ridges and troughs, which in places cut more radially-oriented fractures. The centers of the features also contain radial fractures as well as volcanic domes and flows. Coronae are thought to form due to the upwelling of hot material from deep in the interior of Venus. The two coronae may have formed at the same time over a single upwelling, or may indicate movement of the upwelling or the upper layers of the planet to the west over time. A 'pancake' dome, similar to low-relief domes see in the southern hemisphere, is located just to the southwest of Bahet. Resolution of the Magellan data is about 120 meters (400 feet). ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@mars.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |___ M/S 301-355 | Change is constant. /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | |_____|/ |_|/ |_____|/ |