baalke@mars.jpl.nasa.gov (Ron Baalke) (03/01/91)
=================== MAGELLAN IMAGES February 28, 1991 =================== I've placed two more Magellan images at the Ames SPACE archives, bringing the Magellan total to 12 images. They can be obtained via anonymous ftp from ames.arc.nasa.gov (128.102.18.3), and are in the ftp/pub/SPACE/VICAR directory. The two new files are called arach.img and lavinia.img. All of these images are in VICAR format, and each image has a corresponding caption in text files (with a .txt extension) which contain detailed descriptions of the image. The two new caption files are appended to the end of this message. Most of the VICAR images are 1MB in size. 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 ftp/pub/SPACE/IMDISP directory. I've converted all of the Magellan images into GIF format in 640x480 resolution, and they can be retrieved from the ftp/pub/SPACE/GIF directory. I've decided to do something a little different this time. In order to fit the entire image into a pixel space of 640x480, I've had to subsample the image by a factor of 2 (equivalent to zooming out twice), and this resulted in some of the details in the images being lost. So I've created additional GIF images which zoom in on the more interesting features of the images. From the arach.img and lavinia.img images, there are 6 GIF files. The files arach.gif and lavinia.gif show the entire image. I've created arach1.gif and arach2.gif, which were extracted out of the arach.gif image and show a subsection of arach.gif, but in greater detail. Similarly, lavinia1.gif and lavinia1.gif were created from lavinia.gif. ============================================================================ ARACH.TXT Arachnoids, one of the more remarkable features found on Venus, are seen on radar-dark plains in this Magellan image mosaic in the Fortuna region. The image is centered at about 40 degrees north latitude, 18 degrees longitude. As the name suggests, arachnoids are circular to ovoid features with concentric rings and a complex network of fractures extending outward. In this image, the arachnoids range in size from approximately 50 kilometers (29.9 miles) to 230 kilometers (137.7 miles) in diameter. Since arachnoids are similar in form but generally smaller than coronae (circular volcanic structures surrounded by a set of ridges and grooves as well as radial lines), one theory concerning their origin is that they are a precursor to coronae formation. The radar-bright lines extending for many kilometers may have been caused by an upwelling of magma from the interior of the planet which pushed up the surface to form "cracks." Radar-bright lava flows are present in the central part of this image, also indicative of volcanic activity in this area. Some of the fractures cut across these flows, indicating that the flows occurred before the fractures appeared; such relations between different structures provides good relative age dating of events. At present, arachnoids are found only on Venus and can now be more closely studied with the high resolution (120 meter/0.07 mile) radar imagery from Magellan. ============================================================================ LAVINIA.TXT This is a Magellan full-resolution radar mosaic of the Lavinia region of Venus. The mosaic is centered at 50 degrees south latitude, 345 degrees east longitude, and spans 540 kilometers (338 miles) north to south and 900 kilometers (563 miles) east to west. As with all Magellan images acquired thus far, the illumination of the radar is from the left-hand side of the image. This area shows a diverse set of geologic features. The bright area running from the upper right to the lower left is interpreted as part of a belt of ridges, formed by compression and thickening of the upper layers of the planet. The areas between ridges suggest flooding by radar dark (and thus presumably) smoother lavas. The varied textures of the lavas can be seen in the mottled appearance of the plains which are cut by the ridges; brighter, rougher flows are also quite common. The particularly bright flows in the lower right corner are the northern extension of Mylitta Fluctus. The bright ridges adjacent to Mylitta Fluctus at the bottom center of the image also appear to have been affected by the volcanic activity. Some of these bright features have been interpreted as down-dropped areas roughly 5 kilometers (3 miles) wide. This would imply a region of extension where the crust has been pulled apart and thus was more easily flooded by the later lava flows. The thinner fractures running from the upper left seem to end at the ridge belt in the center of this mosaic. These thinner fractures are a continuation of a pattern seen throughout much of Lavinia and suggest a pattern of compression over a very large region. At the bottom of the image, overlying the ridges, is an impact crater 10-15 kilometers (6-10 miles) in diameter. The double or overlapped crater structure and asymmetrical ejecta pattern suggests that the incoming body broke up shortly before it hit, leaving closely-spaced craters. The placement of the crater on top of the ridges implies it is younger than the ridges; in fact, the crater may be one of the youngest features in this image. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@mars.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | Is it mind over matter, ___| | | | |__) |/ | | |___ M/S 301-355 | or matter over mind? /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | Never mind. |_____|/ |_|/ |_____|/ | It doesn't matter.
baalke@mars.jpl.nasa.gov (Ron Baalke) (03/14/91)
=================== 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 | |_____|/ |_|/ |_____|/ |
baalke@mars.jpl.nasa.gov (Ron Baalke) (03/25/91)
=================== MAGELLAN IMAGES March 24, 1991 =================== I've placed five more Magellan images in VICAR format and 18 in GIF format at the Ames SPACE archives, bringing the Magellan total to 19 VICAR images and 46 GIF images. All of the images are obtainable 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. All of the Magellan images I've uploaded to Ames are public release images from the Magellan project, and are in the public domain and can be freely distributed. The five new VICAR files and their sizes are: alpha.img 1,049,600 bytes lavin.img 1,049,600 bytes ovdac.img 1,574,400 bytes ovdan.img 3,147,776 bytes tick.img 2,347,458 bytes 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 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/SOFTWARE directory. I am one of the programmers for IMDISP, and would welcome any feedback on the program. The VICAR format is used by the Image Processing Lab (MIPL) at JPL. Most of the VICAR images are in 1024x1024 pixel resolution and are about 1MB in size. I've converted all of the Magellan VICAR images into GIF format in 640x480, 256 color resolution. The new GIF files are: alpha.gif ovdac.gif alpha1.gif ovdac1.gif alpha2.gif ovdac2.gif alpha3.gif ovdac3.gif lavina.gif ovdan.gif lavina1.gif ovdan1.gif lavina2.gif ovdan2.gif tick.gif ovdan3.gif tick1.gif tick2.gif ============================================================================ ALPHA.TXT Thirty-six orbits of full-resolution data from the northern edge of central Alpha Regio are shown in this image. The image width is about 600 kilometers (375 miles). The bright lineated terrain is a series of troughs, ridges, and faults that are oriented in many directions. The lengths of these features generally range from 10 kilometers (6.3 miles) to 50 kilometers (31.3 miles). The topographic elevation within Alpha Regio varies over a range of 4 kilometers (2.5 miles). Local topographic lows, whose outlines are generally controlled by structures within the central region, are relatively radar-dark and filled with volcanic lavas. Source vents for this volcanism appear as bright spots within the smooth plains units. A distinct example of late-stage deformation of Alpha is the narrow band of southwest-northeast trending faults that disrupt older terrain between -20 degrees and -22 degrees latitude. Another interesting feature is the 35 kilometers (21.9 miles) diameter volcanic edifice located at the upper right of the image. The center of the volcano is a local topographic low and its western edge appears to be breached. ============================================================================ LAVIN.TXT This Magellan image mosiac located in the Lavinia region shows the crater Carson, a 38 km (23 mile) diameter crater. The image is centered at about 24 degrees south latitude, 344 degrees longitude. Impact craters in the Magellan data are frequently surrounded by radar-dark halos. Several of these halos were noted to have a hyperbolic shape, extending hundreds of kilometers to the west of the craters. Five of these dark halos were also seen extending out from craters in Magellan emissivity data. Magellan emissivity data, derived from the altimeter data, provides information about the porosity (soil versus solid rock) and the composition of the surface. The darkness in the emissivity data indicates a very smooth surface, leading to the interpretation that these halos may be thick, smooth sediment deposits formed by the 'crushing' blow of the atmosphere associated with the incoming projectile that formed the impact crater. But why are only about 5% of the craters surrounded by these halos? On the surface of most planets, the population of impact craters can be used to obtain both relative and absolute surface ages. On Venus, as on Earth, there are relatively few craters, making relative age dating (comparing one region of the planet to another) statistically difficult. The number of craters on Venus indicates that the surface may be only about 400 million years old. The dark halos may indicate the very youngest craters on the planet- where the harsh conditions on Venus have not yet caused these dark halos to 'roughen up' and disappear. The halos could possibly be used as 'geologic clocks.' Volcanic flows or tectonic structures cutting one of these halos are interpreted to have occurred even more recently than the craters. This image shows such a situation, where flows associated with the crater cut across the halo, indicating a very young age. Scientists are continuing to identify these halos in the Magellan data, and use them to understand the geologic evolution of the surface. ============================================================================ OVDAC.TXT This Magellan image shows part the interior of Ovda Regio, one of the large highlands ringing the equator of Venus. Several tectonic events formed this complex block-fractured terrain. An underlying fabric of ridges and valleys strikes NE-SW. These ridges are spaced 10-20 kilometers (6-12 miles) apart and may have been caused by shortening of the crust at right angles to this trend. These structures are cut by throughgoing extension fractures trending NW-SE, suggesting a later episode of NE-SW extension. Lastly, the largest valleys, particularly the 20 kilometer (12 mile)-wide one extending across the image, were filled with dark material, probably lava. The complex internal fabric of Ovda Regio attests to a long history of tectonic deformation. This image, centered approximately at 1 S 81 E, measures 225 kilometers (140 miles) by 150 kilometers (90 miles) and was acquired by Magellan in November 1990. ============================================================================ OVDAN.TXT This Magellan image shows part of the northern boundary of Ovda Regio, one of the large highlands ringing the equator of Venus. The scene consists largely of low-relief, rounded linear ridges. These ridges, 8-15 kilometers (5-9 miles) in width and 30-60 kilometers (20-40 miles) long, lie mostly along a 100-200 kilometer (60-120 mile) wide slope where the elevation drops 3 kilometers (2 miles) from Ovda Regio to the surrounding plains. Some of the ridges have been cut at right angles by extension fractures. Dark material, either lava or windblown dirt, fills the region between the ridges. The curvilinear, banded nature of these ridges suggests that crustal shortening, roughly oriented north-south, is largely responsible for their formation. Such crustal shortening was unexpected by Magellan scientists, who believed that Ovda Regio, a likely site of hot upwelling from the interior of Venus, should be dominated by volcanism and crustal extension. This image, centered approximately at 1 N 81 E, measures 300 kilometers (190 miles) by 225 kilometers (140 miles) and was acquired by Magellan in November 1990. ============================================================================ TICK.TXT This Magellan image is located in the Eistla Region of Venus in the southern hemisphere and is centered at 5.5 degrees east longitude, 18 degrees south latitude. It is 122.8 kilometers (76.1 miles) across east-west and 107.5 kilometers (66.6 miles) across north-south. North is oriented towards the top of the image. Shown in the image is an unusual volcanic edifice unlike all others previously observed. It is approximately 65.6 kilometers (40.7 miles) across at the base and has a relatively flat, slightly concave summit 34.8 kilometers (21.6 miles) in diameter. The sides of the edifice are characterized by radiating ridges and valleys that impart a fluted appearance to the construct. To the west, the rim of the edifice appears to have been breached by dark lava flows that emanated from a shallow summit pit approximately 5.4 kilometers (3.3 miles) in diameter and traveled west along a channel approximately 5.4 kilometers (3.3 miles) wide and 26.8 kilometers (16.6 miles) long. A series of coalescing, collapsed pits 2-10 kilometers (1.2-6.2 miles) in diameter are located 10 kilometers (6.2 miles) west of the summit rim. The edifice and western pits are circumscribed by faint, concentric lineaments up to 70.3 kilometers (43.6 miles) in diameter. A series of north-northwest-trending graben are deflected eastwards around the edifice; the interplay of these graben and the fluted rim of the edifice produce a distinctive scalloped pattern in the image. Several north-northwest-trending lineaments cut directly across the summit region. This peculiar volcanic construct is located 25-30 kilometers (15.5-18.6 miles) north of Alpha Regio, a highly deformed region of tessera terrain. A collection of at least 6 similar volcanoes has been observed near Thetis Regio, a region of tessera within Aphrodite Terra. Thus, these unusual constructs tentatively appear to be spatially associated with regions of tessera. The implications of this spatial association on the unusual morphology of these constructs are being investigated. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@mars.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |___ M/S 301-355 | Change is constant. /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | |_____|/ |_|/ |_____|/ |
baalke@kelvin.jpl.nasa.gov (Ron Baalke) (06/20/91)
=================== MAGELLAN IMAGES June 19, 1991 =================== I've placed 17 more Magellan images at the Ames SPACE archives, bringing the Magellan total to 36 images. These new images are in VICAR format which is the format used at the Image Processing Lab (MIPL) at JPL. The images are obtainable via anonymous ftp from ames.arc.nasa.gov (128.102.18.3), and are in the pub/SPACE/VICAR directory. All of the Magellan images I've put at the Ames site are public release images from the Magellan project, and are in the public domain and can be freely distributed. These new images are *not* on the first Magellan CDROM released earlier this year. The new Magellan files and their sizes are: alcott.img 1,049,600 bytes ammavaru.img 1,312,000 bytes arachcom.img 971,880 bytes barton.img 2,626,020 bytes flows.img 3,616,434 bytes golubnew.img 1,025,145 bytes golubold.img 1,025,145 bytes gulamons.img 914,328 bytes hestia.img 1,422,603 bytes lakshmif.img 822,584 bytes mead.img 1,312,000 bytes navka.img 2,521,800 bytes ovda.img 1,180,310 bytes pandora.img 918,528 bytes sifflows.img 621,600 bytes test25pvo.img 1,006,304 bytes test25rm.img 1,006,304 bytes 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 txt files. 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/SOFTWARE directory, at the same Ames site. IMDISP is the same program distributed with the Voyager and Magellan CDROMs. Since I am one of the programmers for IMDISP, I would welcome any feedback on IMDISP, including any problems encountered with its use or suggestions on improving the program. A new version of IMDISP will be released in a about a couple of weeks; I'll post an an announcement when it is ready. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 301-355 | "Imagination is more /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | important than knowledge" |_____|/ |_|/ |_____|/ | Albert Einstein
datri@convex.com (Anthony A. Datri) (06/21/91)
> The VICAR images can be viewed on an IBM PC computer with the IMDISP
On convex.com [130.168.1.1] can be found pub/xl.3.0.1.patches.Z, which is
a compressed shar archive containing a couple of new files and some patches
to xloadimage version 3.0.1. The patches are largely for speed. The new
files allow xloadimage to view 8-bit VICAR and PDS files. Both the Huffman-
encoded and unencoded variants of the latter are handled. These Magellan
images are examples of VICAR. The files on the Voyager CD-ROMS are examples
of both variants of PDS.
--
Fly to the sky on GI-GI____________ and shout to
datri@convex.com
Chris_F_Chiesa@cup.portal.com (06/21/91)
In a recent posting, Ron Baalke at JPL (baalke@kelvin.jpl.nasa.gov) writes: > =================== > MAGELLAN IMAGES > June 19, 1991 > =================== > > I've placed 17 more Magellan images at the Ames SPACE archives, bringing > the Magellan total to 36 images. These new images are in VICAR format ... I have been TRYING and TRYING for the past year and a half to find a source of this kind of imagery on some kind of MEDIA that I can read at my site. I do not have FTP access, nor is it practical to download megabytes of files at 2400 baud. This posting for some reason gave me an idea that I haven't tried before, which is: Could someone of you who _CAN_ FTP these images, or even Ron Baalke himself, perhaps place them onto a magtape and USmail them to me? I'd be happy to pay a nominal fee for media and shipping if that would help. I can handle 1600 and 6250 bpi 9-track magtape, Exabyte 8mm, and -- in a pinch, and only until August -- IBM-PC 3.5" floppy diskettes. Of the three, I'd prefer the 9-track tapes since those are the most reliable here, but 8mm may not be as unreliable as my colleagues keep telling me... Data formats I can read in- clude VMS Backup (I'm ON a VMS system) and Unix "tar." You see, I work for a company which makes a high-resolution continuous-tone Digital Image Recorder, and once I get hold of an image I can write a program to convert ITS format to OUR format and generate beautiful quality paper or film hardcopy... I have been a "space fan" since early childhood and want very badly to have some images I can hang up in my office, at home, all over the place... etc... Problems so far have been OBTAINING the images, and problems yet to face are those of INTERPRETING the FORMAT. I'd like to re- quest a description of the VICAR format in addition to the imagery, while I'm at it! If anybody reading this thinks they can help me out, or knows someone else who can but who hasn't read this, "pass it on" and e-mail or phone me! Info follows after my signature, below. Thanks in advance, to everyone from the writers of Network software, to the geniuses who build and operate our space probes etc.! Chris Chiesa Chris_F_Chiesa@cup.portal.com (716) 724-2029 weekdays, Eastern time (716) 482-9573 eves/weekends