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M2-F1 lifting body and Pares
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| Title |
M2-F1 lifting body and Paresev 1B on ramp |
| Description |
In this photo of the M2-F1 lifting body and the Paresev 1B on the ramp, the viewer sees two vehicles representing different approaches to building a research craft to simulate a spacecraft able to land on the ground instead of splashing down in the ocean as the Mercury capsules did. The M2-F1 was a lifting body, a shape able to re-enter from orbit and land. The Paresev (Paraglider Research Vehicle) used a Rogallo wing that could be (but never was) used to replace a conventional parachute for landing a capsule-type spacecraft, allowing it to make a controlled landing on the ground. The wingless, lifting body aircraft design was initially conceived as a means of landing an aircraft horizontally after atmospheric reentry. The absence of wings would make the extreme heat of re-entry less damaging to the vehicle. In 1962, Dryden management approved a program to build a lightweight, unpowered lifting body as a prototype to flight test the wingless concept. It would look like a "flying bathtub," and was designated the M2-F1, the "M" referring to "manned" and "F" referring to "flight" version. It featured a plywood shell placed over a tubular steel frame crafted at Dryden. Construction was completed in 1963. The first flight tests of the M2-F1 were over Rogers Dry Lake at the end of a tow rope attached to a hopped-up Pontiac convertible driven at speeds up to about 120 mph. This vehicle needed to be able to tow the M2-F1 on the Rogers Dry Lakebed adjacent to NASA's Flight Research Center (FRC) at a minimum speed of 100 miles per hour. To do that, it had to handle the 400-pound pull of the M2-F1. Walter "Whitey" Whiteside, who was a retired Air Force maintenance officer working in the FRC's Flight Operations Division, was a dirt-bike rider and hot-rodder. Together with Boyden "Bud" Bearce in the Procurement and Supply Branch of the FRC, Whitey acquired a Pontiac Catalina convertible with the largest engine available. He took the car to Bill Straup's renowned hot-rod shop near Long Beach for modification. With a special gearbox and racing slicks, the Pontiac could tow the 1,000-pound M2-F1 110 miles per hour in 30 seconds. It proved adequate for the roughly 400 car tows that got the M2-F1 airborne to prove it could fly safely and to train pilots before they were towed behind a C-47 aircraft and released. These initial car-tow tests produced enough flight data about the M2-F1 to proceed with flights behind the C-47 tow plane at greater altitudes. The C-47 took the craft to an altitude of 12,000 where free flights back to Rogers Dry Lake began. Pilot for the first series of flights of the M2-F1 was NASA research pilot Milt Thompson. Typical glide flights with the M2-F1 lasted about two minutes and reached speeds of 110 to l20 mph. A small solid landing rocket, referred to as the "instant L/D rocket," was installed in the rear base of the M2-F1. This rocket, which could be ignited by the pilot, provided about 250 pounds of thrust for about 10 seconds. The, Rogallo wing was never used on a spacecraft, it revolutionized the sport of hang gliding, and a different but related kind of wing will be used on the X-38 technology demonstrator for a crew return vehicle from the International space station., referred to as a `space frame.' The keel and leading edges of the wings were constructed of 2 1/2-inch diameter aluminum tubing. The leading edge sweep angle was held constant at 50 degrees by a rigid spreader bar. Additional wing structure fabricated of steel tubing ensured structural integrity. Seven weeks after the project was initiated the team rolled out the Paresev 1. It resembled a grown-up tricycle, with a rudimentary seat, an angled tripod mast, and, perched on top of the mast, a Rogallo-type parawing. The pilot sat out in the open, strapped in the seat, with no enclosure of any kind. He controlled the descent rate by tilting the wing fore and aft, and turned by tilting the wing from side to side with a control stick that came from overhead. NASA registered the Paresev, the first NASA research airplane to be constructed totally "in-house," with the Federal Aviation Administration on February 12, 1962. Flight testing started immediately. There was one space frame built called the Paresev that used four different wing types. Paresev 1 had a linen membrane, with the control stick coming from overhead in front of the pilots seat. Paresev 1A had a regulation control stick and a Dacron membrane. Paresev 1B had a smaller Dacron membrane with the space frame remaining the same. Paresev 1C used a half-scale version of the inflatable Gemini parawing with a small change to the space frame. All `space frames,' regardless of the parawing configuration, had a shield with "Paresev 1-A" and the NASA meatball on the front of the vehicle. PARESEV-1 After the space frame was completed a sailmaker was asked to sew the wing membrane according to the planform developed by NASA Flight Research Center personnel. He suggested using Dacron instead of the linen fabric chosen, but yielded to the engineers' specs. A nylon bolt rope was attached in the trailing edge of the 150-square-foot wing membrane. The rope was unrestrained except at the wing tips and was therefore free to equalize the load between the two lobes of the wing. This worked reasonably well, but flight tests proved the wing to be too flexible with it flapping and bulging in alarming ways. The poor membrane design led to trailing edge flutter, with longitudinal and lateral stick forces being severe. A number of different rigging modifications to improve the flying characteristics were tried, but very few were successful and none were predictable. Everything seemed to affect stick forces in the worst way. The fifth flight aloft lasted 10 seconds. On a ground tow the Paresev and pilot fell 10 feet. Considerable damage was done to the Paresev with the pilot, Bruce Peterson, being taken to the base hospital. Injuries sustained by the pilot were not serious. After this accident the Paresev was extensively rebuilt and renamed, Paresev-1A. PARESEV 1-A The sailmaker was asked again to construct a 150-square-foot membrane the way he wanted to. The resulting wing membrane had excellent contours in flight and, rocket could be used to extend the flight time near landing if needed. More than 400 ground tows and 77 aircraft tow flights were carried out with the M2-F1. The success of Dryden's M2-F1 program led to NASA's development and construction of two heavyweight lifting bodies based on studies at NASA's Ames and Langley research centers--the M2-F2 and the HL-10, both built by the Northrop Corporation, and the U.S. Air Force's X-24 program, with an X-24A and -B built by Martin. The Lifting Body program also heavily influenced the Space Shuttle program. The M2-F1 program demonstrated the feasibility of the lifting body concept for horizontal landings of atmospheric entry vehicles. It also demonstrated a procurement and management concept for prototype flight test vehicles that produced rapid results at very low cost (approximately $50,000, excluding salaries of government employees assigned to the project). The Paresev (Paraglider Rescue Vehicle) was an indirect outgrowth of kite-parachute studies by NACA Langley engineer Francis M. Rogallo. In the early 1960s the "Rogallo wing" seemed an excellent means of returning a spacecraft to Earth. The delta wing design was patented by Mr. Rogallo. In May 1961, Robert R. Gilruth, director NASA's Space Task Group, requested studies of an inflatable Rogallo-type "Parawing" for spacecraft. Several companies responded, North American Aviation produced the most acceptable concept and development was contracted to that company. In November 1961 NASA Headquarters launched a paraglider development program, with Langely doing wind-tunnel studies and the NASA Flight Research Center supporting the North American test program. The North American concept was a capsule type vehicle with a stowed "parawing" that could be deployed and controlled from within for a landing more like an airplane instead of a "splash down" in the ocean as was the practice in the Mercury and later the Gemini and Apollo programs. The logistics became enormous and the price exorbitant, besides which, NASA pilots and engineers felt some baseline experience like building a vehicle and flying a Parawing should be accomplished first. The Paresev (Paraglider Research Vehicle) was used to gain in-flight experience with four different membranes (wings) and was not used to develop the more complicated inflatable deployment system. The Paresev was designed by Charles Richard, of the Flight Research Center's Vehicle and System Dynamics Branch, with the rest of the team being: engineers Richard Klein, Gary Layton, John Orahood, and Joe Wilson, Frank Fedor and LeRoy Barto from the Maintenance and Manufacturing Branch, Project Manager Victor Horton, with Gary Layton becoming Project Manager later on in the Program. Mr. Paul Bikle, Director of the Center, gave instructions that were short and to the point: build a single-seat Paraglider and "do it quick and cheap." The Paresev was unpowered, the "fuselage" an open framework fabricated of welded 4130 steel tubing, was made from 6 ounce Dacron. The space frame was rebuilt with more sophistication than the Paresev 1 had. The shock absorbers were Ford automotive parts, the wing universal joint was a 1948 Pontiac part, and the tires and wheels were from a Cessna 175 aircraft. The overhead stick was replaced with a stick and pulley arrangement that operated more like conventional aircraft controls. This vehicle had much improved stick forces and handling qualities. The instrumentation used to obtain data was quite crude, partially as a result of the desire to keep the program simple and low in cost and also because there was no onboard power. To measure performance, technicians installed a large alpha vane on the wing apex with a scale at the trailing edge that the pilot could read directly. A curved bubble level measured the vehicle's attitude, and a Fairchild camera recorded the glide slope PARESEV 1-B The Paresev 1-B used the Paresev 1-A space frame with a smaller Dacron wing (100 square feet) and was flight tested to evaluate its handling qualities with lower lift-to-drag values. One NASA project engineer described its gliding ability as "pretty scary." PARESEV 1-C The space frame of the vehicle remained almost unchanged from the earlier vehicles. However, a new control box gave the pilot the ability to increase or decrease the nitrogen in the inflatable wing supports to compensate for the changing density of the air. Two bottles of nitrogen provided an extra supply of nitrogen. The vehicle featured a partially inflatable wing. The whole wing was not inflatable, the three chambers that acted as spars and supported the wing inflated. The center spar ran fore and aft and measured 191 inches, two other inflatable spars formed the leading edges. These three compartments were filled with nitrogen under pressure to make them rigid. The Paresev in this configuration was expected to closely approximate the aerodynamic characteristics that would be encountered with the Gemini space capsule with a parawing extended. The Paresev was very unstable in flight with this configuration. The first Paresev flights began with tows across the dry lakebed, in 1962, using a NASA vehicle, an International Harvester carry-all (6 cylinder). Eventually ground and airtows were done using a Stearman sport biplane (450 hp), a Piper Super Cub (150-180 hp), Cessna L-19 (200 hp Bird Dog) and a Boeing-Vertol HC-1A. Speed range of the Paresev was about 35-65 mph. The Paresev completed nearly 350 flights during a research program from 1962 until 1964. Pilots flying the Paresev included NASA pilots Milton Thompson, Bruce Peterson, and Neil Armstrong from Dryden, Robert Champine from Langley, and astronaut Gus Grissom, plus North American test pilot Charles Hetzel. The Paresev was legally transferred to the National Air and Space Museum of the Smithsonian Institute, Washington, D.C. Despite its looks, the Paresev was a useful research aircraft that helped develop a new way to fly. Although the |
| Date |
01.01.1963 |
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Nez Perce Reservation : Imag
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nasa, nasaimageofthedaygalle
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The Clearwater River cuts ca
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nezperce_l7_1999190
| mediatype |
IMAGE |
| mediatype |
image |
| date |
1999-07-09 |
| creator |
NASA -- NASA image created by Jesse Allen, Earth Observatory, using data obtained from the University of Maryland's glcf.umiacs.umd.edu/index.shtml Global Land Cover Facility. |
| identifier |
nezperce_l7_1999190 |
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Alluvial Fan Along a Crater
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PIA09666
Sol (our sun)
HiRISE
| Title |
Alluvial Fan Along a Crater Wall |
| Original Caption Released with Image |
Click on image for larger version This HiRISE image (PSP_003269_1600 [ http://hirise.lpl.arizona.edu/PSP_003269_1600 ]) covers an alluvial fan along the wall of a large crater in the mid latitudes of the southern hemisphere of Mars. The fan was formed when water and sediments drained down the steep wall of the crater creating a cone-shaped pile of debris at the base. As the fan grew with time, the channels carrying water and sediment across the fan surface changed locations, producing a layered deposit capped by channels radiating from the fan apex along the crater wall. Subsequent stripping of the fan surface by the wind has left the coarser channel deposits in relief and exposed the fine scale layering within the fan in many locations. While is it is not known whether the source of the water responsible for creating the fan was related runoff from precipitation or groundwater or perhaps both, alluvial fans of broadly similar form are observed in many locations on Earth and are usually formed by runoff from precipitation. Observation Toolbox Acquisition date: 4 April 2007 Local Mars time: 3:42 PM Degrees latitude (centered): -19.9° Degrees longitude (East): 123.2° Range to target site: 258.6 km (161.6 miles) Original image scale range: 25.9 cm/pixel (with 1 x 1 binning) so objects ~78 cm across are resolved Map-projected scale: 25 cm/pixel and north is up Map-projection: EQUIRECTANGULAR Emission angle: 4.7° Phase angle: 48.6° Solar incidence angle: 53°, with the Sun about 37° above the horizon Solar longitude: 215.1°, Northern Autumn NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo. |
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Alluvial Fan Along a Crater
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PIA09666
Sol (our sun)
HiRISE
| Title |
Alluvial Fan Along a Crater Wall |
| Original Caption Released with Image |
Click on image for larger version This HiRISE image (PSP_003269_1600 [ http://hirise.lpl.arizona.edu/PSP_003269_1600 ]) covers an alluvial fan along the wall of a large crater in the mid latitudes of the southern hemisphere of Mars. The fan was formed when water and sediments drained down the steep wall of the crater creating a cone-shaped pile of debris at the base. As the fan grew with time, the channels carrying water and sediment across the fan surface changed locations, producing a layered deposit capped by channels radiating from the fan apex along the crater wall. Subsequent stripping of the fan surface by the wind has left the coarser channel deposits in relief and exposed the fine scale layering within the fan in many locations. While is it is not known whether the source of the water responsible for creating the fan was related runoff from precipitation or groundwater or perhaps both, alluvial fans of broadly similar form are observed in many locations on Earth and are usually formed by runoff from precipitation. Observation Toolbox Acquisition date: 4 April 2007 Local Mars time: 3:42 PM Degrees latitude (centered): -19.9° Degrees longitude (East): 123.2° Range to target site: 258.6 km (161.6 miles) Original image scale range: 25.9 cm/pixel (with 1 x 1 binning) so objects ~78 cm across are resolved Map-projected scale: 25 cm/pixel and north is up Map-projection: EQUIRECTANGULAR Emission angle: 4.7° Phase angle: 48.6° Solar incidence angle: 53°, with the Sun about 37° above the horizon Solar longitude: 215.1°, Northern Autumn NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo. |
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Alluvial Fans in Mojave Crat
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PIA09399
Sol (our sun)
HiRISE
| Title |
Alluvial Fans in Mojave Crater: Did It Rain on Mars? |
| Original Caption Released with Image |
Click on image for larger version This HiRISE image at up to 29 cm/pixel scale supports the alluvial fan interpretation, in particular by showing that the sizes of the largest rocks decrease away from the mouths of the fans. Aptly-named Mojave crater in the Xanthe Terra region has alluvial fans that look remarkably similar to landforms in the Mojave Desert of southeastern California and portions of Nevada and Arizona. Alluvial fans are fan-shaped deposits of water-transported material (alluvium). They typically form at the base of hills or mountains where there is a marked break, or flattening of slope. They typically deposit big rocks near their mouths (close to the mountains) and smaller rocks at greater distances. Alluvial fans form as a result of heavy desert downpours, typically thundershowers. Because deserts are poorly vegetated, heavy and short-lived downpours create a great deal of erosion and nearby deposition. There are fans inside and around the outsides of Mojave crater on Mars that perfectly match the morphology of alluvial fans on Earth, with the exception of a few small impact craters dotting this Martian landscape. Channels begin at the apex of topographic ridges, consistent with precipitation as the source of water, rather than groundwater. This remarkable landscape was first discovered from Mars Orbital Camera images. Mars researchers have suggested that impact-induced atmospheric precipitation may have created these unique landscapes. Image PSP_001415_1875 [ http://hiroc.lpl.arizona.edu/images/PSP/PSP_001415_1875/ ] was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on November 14, 2006. The complete image is centered at 7.6 degrees latitude, 327.4 degrees East longitude. The range to the target site was 273.5 km (170.9 miles). At this distance the image scale ranges from 27.4 cm/pixel (with 1 x 1 binning) to 109.4 cm/pixel (with 4 x 4 binning). The image shown here has been map-projected to 25 cm/pixel and north is up. The image was taken at a local Mars time of 3:29 PM and the scene is illuminated from the west with a solar incidence angle of 52 degrees, thus the sun was about 38 degrees above the horizon. At a solar longitude of 135.4 degrees, the season on Mars is Northern Summer. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo. |
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Alluvial Fans in Mojave Crat
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PIA09399
Sol (our sun)
HiRISE
| Title |
Alluvial Fans in Mojave Crater: Did It Rain on Mars? |
| Original Caption Released with Image |
Click on image for larger version This HiRISE image at up to 29 cm/pixel scale supports the alluvial fan interpretation, in particular by showing that the sizes of the largest rocks decrease away from the mouths of the fans. Aptly-named Mojave crater in the Xanthe Terra region has alluvial fans that look remarkably similar to landforms in the Mojave Desert of southeastern California and portions of Nevada and Arizona. Alluvial fans are fan-shaped deposits of water-transported material (alluvium). They typically form at the base of hills or mountains where there is a marked break, or flattening of slope. They typically deposit big rocks near their mouths (close to the mountains) and smaller rocks at greater distances. Alluvial fans form as a result of heavy desert downpours, typically thundershowers. Because deserts are poorly vegetated, heavy and short-lived downpours create a great deal of erosion and nearby deposition. There are fans inside and around the outsides of Mojave crater on Mars that perfectly match the morphology of alluvial fans on Earth, with the exception of a few small impact craters dotting this Martian landscape. Channels begin at the apex of topographic ridges, consistent with precipitation as the source of water, rather than groundwater. This remarkable landscape was first discovered from Mars Orbital Camera images. Mars researchers have suggested that impact-induced atmospheric precipitation may have created these unique landscapes. Image PSP_001415_1875 [ http://hiroc.lpl.arizona.edu/images/PSP/PSP_001415_1875/ ] was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on November 14, 2006. The complete image is centered at 7.6 degrees latitude, 327.4 degrees East longitude. The range to the target site was 273.5 km (170.9 miles). At this distance the image scale ranges from 27.4 cm/pixel (with 1 x 1 binning) to 109.4 cm/pixel (with 4 x 4 binning). The image shown here has been map-projected to 25 cm/pixel and north is up. The image was taken at a local Mars time of 3:29 PM and the scene is illuminated from the west with a solar incidence angle of 52 degrees, thus the sun was about 38 degrees above the horizon. At a solar longitude of 135.4 degrees, the season on Mars is Northern Summer. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo. |
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The Nile
PIA02647
Sol (our sun)
Multi-angle Imaging SpectroR
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| Title |
The Nile |
| Original Caption Released with Image |
This image of the northern portion of the Nile River was captured by MISR's nadir camera on January 30, 2001 (Terra orbit 5956). The Nile is the longest river in the world, extending for about 6700 kilometers from its headwaters in the highlands of eastern Africa. At the apex of the fertile Nile River Delta is the Egyptian capital city of Cairo. To the west are the Great Pyramids of Giza. North of here the Nile branches into two distributaries, the Rosetta to the west and the Damietta to the east. Also visible in this image is the Suez Canal, a shipping waterway connecting Port Said on the Mediterranean Sea with the Gulf of Suez. The Gulf is an arm of the Red Sea, and is located on the righthand side of the picture. MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology. |
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MISR Views the Middle East
PIA02626
Sol (our sun)
Multi-angle Imaging SpectroR
…
| Title |
MISR Views the Middle East |
| Original Caption Released with Image |
This image, generated using 16 orbits of MISR data collected between August 16 and August 30, 2000, takes us to the cradle of many civilizations. The data are from the 60-degree aftward-viewing camera. Because the individual orbit swaths are only 400 kilometers wide, they were "mosaiced" together to form this composite picture, which covers about 2700 kilometers from west to east and 1750 kilometers from north to south. A few discontinuities are present in the mosaic, particularly near clouds, due to changes in the scene which occurred between dates when the individual orbit data were acquired. At the northern tip of the Red Sea, the Gulf of Suez and the Gulf of Aqaba frame the sandy deserts and spectacular mountains of the Sinai Peninsula. The highest peaks are Gebel Katherina (Mountain of St. Catherine, 2637 meters) and Gebel Musa (Mountain of Moses, also known as Mount Sinai, 2285 meters). To the northeast, Israel and Jordan flank the Dead Sea, one of the saltiest inland water bodies in the world. At its northern edge is Qumran, where the ancient Scrolls were discovered, the city of Jerusalem lies about 30 kilometers to the west. Several large rivers are prominent. Flowing southeastward through Iraq are the Tigris and Euphrates. The dark area between the two rivers, northwest of the Persian Gulf, is a very fertile region where fishing and farming are prevalent. Wending its way through eastern Egypt is the Nile. In the south is Lake Nasser and the Aswan Dam, continuing northward the Nile passes the Temple of Luxor as it sharply loops to the east. It then turns west and northward, eventually passing the capital city of Cairo, and finally spreading into a prominent delta as it empties into the Mediterranean Sea. The bright dot just west of the apex of the delta marks the location of the great Pyramids and Sphinx complexes on the Giza Plateau. On the coast, west of the delta, is the ancient city of Alexandria, Egypt's main seaport."MISR", as it turns out, is the transliteration of the Arabic name for Egypt. MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology. |
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Europa Impact Crater
PIA02561
Jupiter
Near Infrared Mapping Spectr
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| Title |
Europa Impact Crater |
| Original Caption Released with Image |
A newly discovered, city-sized impact crater viewed by NASA's Galileo spacecraft may shed new light on the nature of the enigmatic icy surface of Jupiter's moon Europa. This false-color image reveals the scar of a past major impact of a comet or small asteroid on Europa's surface. The bright, circular feature at center right has a diameter of about 80 kilometers (50 miles), making it comparable in size to the largest cities on Earth. The area within the outer boundary of the continuous bright ring is about 5,000 square kilometers (nearly 2,000 square miles). The diameter of the darker area within the bright ring is about 29 kilometers (18 miles), which is large enough to contain both the city of San Francisco and New York's Manhattan Island, side by side. The brightest reds in this image correspond to surfaces with high proportions of relatively pure water ice, while the blue colors indicate that non-ice materials are also present. The composition of the darker materials is controversial, they may consist of minerals formed by evaporation of salty brines, or they may be rich in sulfuric acid. The bright ring is a blanket of ejecta that consists of icy subsurface material that was blasted out of the crater by the impact, while the darker area in the center may retain some of the materials from the impacting body. Further study may yield new insights about both the nature of the impactor and the surface chemistry of Europa. Europa's surface is a question of great interest at present, since an ocean of liquid water may exist beneath the icy crust, possibly providing an environment suitable for life. Geologic investigations of Europa's surface are underway, and a new spacecraft mission, the Europa Orbiter, is planned. Impact craters with diameters of 20 kilometers (12 miles) and larger are extremely rare on Europa, as of 1999 only 7 such features were known. The rarity of larger impact craters on Europa lends greater significance to the discovery of this one. Impact crater counts are often employed to estimate the ages of the exposed surfaces of planets and satellites, and the small number of craters found on Europa implies that the surface may be quite young in geological terms. Thus the discovery of this feature may provide additional insights into questions about the age and level of geological activity of Europa's surface. Impact craters are expected to form with greater frequency on the "leading" sides of satellites that always turn the same face to their primary planet, in this case, Jupiter. The process is much like the effect of running through a rainstorm. The "apex" of Europa's leading side is located on the equator at 90 degrees West longitude, only about 10 degrees removed from the feature shown. Europa's leading side does not receive a continuous bombardment by ionized particles carried along by Jupiter's rapidly rotating magnetosphere (as is the case for the trailing side), which may allow greater preservation of the chemical, signatures of the impacting object. To the east of the bright ring-like feature are two, or perhaps three, similar but less well-defined quasi-circular features, raising the possibility that this crater is one member of a catena, or chain of craters. This would lend still greater interest to this area as a potential target for focused investigations by later missions such as the Europa Orbiter. The near-infrared mapping spectrometer on board Galileo obtained this image on May 31,1998, during that spacecraft's 15th orbital encounter with Europa. The image data was returned to Earth in several segments during both the 15th and the 16th orbital periods. Merging and processing of the full data set was accomplished in 1999. Analysis and interpretation are ongoing. Galileo has been orbiting Jupiter and its moons since December 1995. Its primary mission ended in December 1997, and after that Galileo successfully completed a two-year extended mission. The spacecraft is in the midst of yet another extended journey called the Galileo Millennium Mission. More information about the Galileo mission is available at:http://galileo.jpl.nasa.gov [ http://galileo.jpl.nasa.gov ]JPL manages Galileo for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena. |
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