[meteorite-list] Meteorite Picture of the Day
Today's Meteorite Picture of the Day: Agoult Contributed by: Solar Anamnesis http://www.tucsonmeteorites.com/mpodmain.asp?DD=03/04/2017 __ Visit our Facebook page https://www.facebook.com/meteoritecentral and the Archives at http://www.meteorite-list-archives.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com https://pairlist3.pair.net/mailman/listinfo/meteorite-list
[meteorite-list] AD > Amazing dual lithology lunar for sale
Hi everyone, Here's one of my auctions, for an amazing dual lithology lunar slice : NWA 10272. www.ebay.com/itm/Lunar-meteorite-NWA-10272-feldspathic-breccia-with-2-lithologies-incredible-/112322314210 Pierre-Marie Pelé Meteor-Center Météorites : achat - vente - expertise - expéditions - recherche http://www.meteor-center.com Membre de la Meteoritical Society Membre de l'International Meteorite Association Collectors __ Visit our Facebook page https://www.facebook.com/meteoritecentral and the Archives at http://www.meteorite-list-archives.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com https://pairlist3.pair.net/mailman/listinfo/meteorite-list
[meteorite-list] MAVEN Orbiter Steers Clear of Mars Moon Phobos
https://www.jpl.nasa.gov/news/news.php?feature=6764 NASA Orbiter Steers Clear of Mars Moon Phobos Jet Propulsion Laboratory March 2, 2017 NASA's MAVEN spacecraft performed a previously unscheduled maneuver this week to avoid a collision in the near future with Mars' moon Phobos. The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft has been orbiting Mars for just over two years, studying the Red Planet's upper atmosphere, ionosphere and interactions with the sun and solar wind. On Tuesday, Feb. 28, the spacecraft carried out a rocket motor burn that boosted its velocity by 0.4 meters per second (less than 1 mile per hour). Although a small correction, it was enough that -- projected to one week later when the collision would otherwise have occurred -- MAVEN would miss the lumpy, crater-filled moon by about 2.5 minutes. This is the first collision avoidance maneuver that the MAVEN spacecraft has performed at Mars to steer clear of Phobos. The orbits of both MAVEN and Phobos are known well enough that this timing difference ensures that they will not collide. MAVEN, with an elliptical orbit around Mars, has an orbit that crosses those of other spacecraft and the moon Phobos many times over the course of a year. When the orbits cross, the objects have the possibility of colliding if they arrive at that intersection at the same time. These scenarios are known well in advance and are carefully monitored by NASA's Jet Propulsion Laboratory in Pasadena, California, which sounded the alert regarding the possibility of a collision. With one week's advance notice, it looked like MAVEN and Phobos had a good chance of hitting each other on Monday, March 6, arriving at their orbit crossing point within about 7 seconds of each other. Given Phobos' size (modeled for simplicity as a 30-kilometer sphere, a bit larger than the actual moon in order to be conservative), they had a high probability of colliding if no action were taken. Said MAVEN Principal Investigator Bruce Jakosky of the University of Colorado in Boulder, "Kudos to the JPL navigation and tracking teams for watching out for possible collisions every day of the year, and to the MAVEN spacecraft team for carrying out the maneuver flawlessly." MAVEN's principal investigator is based at the University of Colorado's Laboratory for Atmospheric and Space Physics, Boulder. The university provided two science instruments and leads science operations, as well as education and public outreach, for the mission. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the MAVEN project and provided two science instruments for the mission. Lockheed Martin built the spacecraft and is responsible for mission operations. The University of California at Berkeley's Space Sciences Laboratory also provided four science instruments for the mission. NASA's Jet Propulsion Laboratory in Pasadena, California, provides navigation and Deep Space Network support, as well as the Electra telecommunications relay hardware and operations. News Media Contact By Nancy Neal Jones NASA's Goddard Space Flight Center in Greenbelt, Maryland 301-286-0039 nancy.n.jo...@nasa.gov Laurie Cantillo NASA Headquarters, Washington Guy Webster Jet Propulsion Laboratory, Pasadena, Calif. 818-354-6278 guy.webs...@jpl.nasa.gov 2017-057 __ Visit our Facebook page https://www.facebook.com/meteoritecentral and the Archives at http://www.meteorite-list-archives.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com https://pairlist3.pair.net/mailman/listinfo/meteorite-list
[meteorite-list] Dawn Journal - February 27, 2017
http://dawn.jpl.nasa.gov/mission/journal_02_27_17.html Dawn Journal Dr. Marc Rayman February 27, 2017 Dear Pedawntic Readers, A sophisticated spaceship in orbit around an alien world has been firing its advanced ion engine to execute complex and elegant orbital acrobatics. On assignment from Earth at dwarf planet Ceres, Dawn is performing like the ace flier that it is. The spacecraft's activities are part of an ambitious bonus goal the team has recently devised for the extended mission. Dawn will maneuver to a location exactly on the line connecting Ceres and the sun and take pictures and spectra there. Measuring the opposition surge we explained last month will help scientists gain insight into the microscopic nature of the famous bright material in Occator Crater. Flying to that special position and acquiring the pictures and spectra will consume most of the rest of the extended mission, which concludes on June 30. This month, we will look at the probe's intricate maneuvers. Next month, we will delve more into the opposition surge itself, and in April we will describe Dawn's detailed plans for photography and spectroscopy. In May we will discuss further maneuvers that could provide a backup opportunity for observing the opposition surge in June. [Image of Ernutet Crater] This image combines several photographs of Ernutet Crater taken through different color filters in Dawn's science camera. (Ernutet was an Egyptian goddess, often depicted with the head of a cobra, who provided food and protected grains by eating pests such as rodents.) The colors have been enhanced to bring out subtle differences in the chemical composition of the material covering the ground that would not be visible to your unaided eye (even assuming your unaided eye were in the vicinity of Ceres). Using data acquired by the spacecraft's infrared mapping spectrometer, scientists have determined that the red regions are rich in organic compounds. The organic molecules are based on chains of carbon atoms and represent a class of chemicals important in biochemistry. Such a finding, along with Dawn's earlier discoveries of ice and other chemicals that likely were formed through interactions with water, makes Ceres very interesting for studies of astrobiology. Nevertheless, future colonists on Ceres would be expected to have little need for protection from native pestilential threats. The 32-mile (52-kilometer) Ernutet Crater is on this map at 53°N, 46°E. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA First, however, it is worth recalling that this is not Dawn's primary responsibility, which is to continue to measure cosmic rays in order to improve scientists' ability to establish the atomic species down to about a yard (meter) underground. Sensing the space radiation requires the spacecraft to stay more than 4,500 miles (7,200 kilometers) above the dwarf planet that is its gravitational master. The gamma ray and neutron detector will be operated continuously as Dawn changes its orbit and then performs the new observations. The ongoing high-priority radiation measurements will not be affected by the new plans. The principal objective of the orbital maneuvers is to swivel Dawn's orbit around Ceres. Imagine looking down on Ceres' north pole, with the sun far to the left. (To help your imagination, you might refer to this figure from last month. As we will explain in May, Dawn's orbital plane is slowly rotating clockwise, according to plan, and it is now even closer to vertical than depicted in January. That does not affect the following discussion.) From your perspective, looking edge-on at Dawn's orbit, its elliptical path looks like a line, just as does a coin seen from the edge. In its current orbit (labeled 6 in that figure), Dawn moves from the bottom to the top over the north pole. When it is over the south pole, on the other side of the orbit, it flies from the top of the figure back to the bottom. The purpose of the current maneuvering is to make Dawn travel instead from the left to the right over the north pole (and from the right to the left over the south pole). This is equivalent to rotating the plane of the orbit around the axis that extends through Ceres' poles and up to Dawn's altitude. From the sun's perspective, Dawn starts by revolving counterclockwise and the orbit is face-on. We want to turn it so it is edge-on to the sun. That may not sound very difficult. After all, it amounts mostly to turning right at the north pole or left at the south pole. Spaceships in science fiction do that all the time (although sometimes they turn right at the south pole). However, it turns out to be extremely difficult in reality, not to mention lacking the cool sounds. When going over the south pole, from the top of the figure to the bottom, the spacecraft has momentum in that direction. To turn, it needs to cancel that out and then develop momentum to the left.
[meteorite-list] Martian Winds Carve Mountains, Move Dust, Raise Dust (MSL)
https://www.jpl.nasa.gov/news/news.php?feature=6758 Martian Winds Carve Mountains, Move Dust, Raise Dust Jet Propulsion Laboratory February 27, 2017 Fast Facts: * Wind is a dominant force shaping landscapes on Mars, despite the thin air. * A recent study supports the idea that a mountain that is oddly in the middle of a Martian crater was formed by wind subtracting other material after the crater had been filled to the brim with sediments. * Modern winds in the crater show effects such as dusty whirlwinds, shifting sand and active dunes. * NASA's Mars rover Curiosity has begun investigating linear-shaped dunes during the crater's windy summer season. On Mars, wind rules. Wind has been shaping the Red Planet's landscapes for billions of years and continues to do so today. Studies using both a NASA orbiter and a rover reveal its effects on scales grand to tiny on the strangely structured landscapes within Gale Crater. NASA's Curiosity Mars rover, on the lower slope of Mount Sharp -- a layered mountain inside the crater -- has begun a second campaign of investigating active sand dunes on the mountain's northwestern flank. The rover also has been observing whirlwinds carrying dust and checking how far the wind moves grains of sand in a single day's time. Gale Crater observations by NASA's Mars Reconnaissance Orbiter have confirmed long-term patterns and rates of wind erosion that help explain the oddity of having a layered mountain in the middle of an impact crater. "The orbiter perspective gives us the bigger picture -- on all sides of Mount Sharp and the regional context for Gale Crater. We combine that with the local detail and ground-truth we get from the rover," said Mackenzie Day of the University of Texas, Austin, lead author of a research report in the journal Icarus about wind's dominant role at Gale. The combined observations show that wind patterns in the crater today differ from when winds from the north removed the material that once filled the space between Mount Sharp and the crater rim. Now, Mount Sharp itself has become a major factor in determining local wind directions. Wind shaped the mountain; now the mountain shapes the wind. The Martian atmosphere is about a hundred times thinner than Earth's, so winds on Mars exert much less force than winds on Earth. Time is the factor that makes Martian winds so dominant in shaping the landscape. Most forces that shape Earth's landscapes -- water that erodes and moves sediments, tectonic activity that builds mountains and recycles the planet's crust, active volcanism -- haven't influenced Mars much for billions of years. Sand transported by wind, even if infrequent, can whittle away Martian landscapes over that much time. How to Make a Layered Mountain Gale Crater was born when the impact of an asteroid or comet more than 3.6 billion years ago excavated a basin nearly 100 miles (160 kilometers) wide. Sediments including rocks, sand and silt later filled the basin, some delivered by rivers that flowed in from higher ground surrounding Gale. Curiosity has found evidence of that wet era from more than 3 billion years ago. A turning point in Gale's history -- when net accumulation of sediments flipped to net removal by wind erosion -- may have coincided with a key turning point in the planet's climate as Mars became drier, Day noted. Scientists first proposed in 2000 that the mound at the center of Gale Crater is a remnant from wind eroding what had been a totally filled basin. The new work calculates that the vast volume of material removed -- about 15,000 cubic miles (64,000 cubic kilometers) -- is consistent with orbital observations of winds' effects in and around the crater, when multiplied by a billion or more years. Other new research, using Curiosity, focuses on modern wind activity in Gale. The rover this month is investigating a type of sand dune that differs in shape from dunes the mission investigated in late 2015 and early 2016. Crescent-shaped dunes were the feature of the earlier campaign -- the first ever up-close study of active sand dunes anywhere other than Earth. The mission's second dune campaign is at a group of ribbon-shaped linear dunes. "In these linear dunes, the sand is transported along the ribbon pathway, while the ribbon can oscillate back and forth, side to side," said Nathan Bridges, a Curiosity science team member at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. The season at Gale Crater is now summer, the windiest time of year. That's the other chief difference from the first dune campaign, conducted during less-windy Martian winter. "We're keeping Curiosity busy in an area with lots of sand at a season when there's plenty of wind blowing it around," said Curiosity Project Scientist Ashwin Vasavada of NASA's Jet Propulsion Laboratory, Pasadena, California. "One aspect we want to learn more about is the wind's effect
[meteorite-list] AD - St. Patrick's Day
Something special for Saint Patrick's Day, March 17. http://www.tucsonmeteorites.com/limerick.asp Cheers Paul Swartz IMCA 5204 Meteorite Picture of the Day Web Master __ Visit our Facebook page https://www.facebook.com/meteoritecentral and the Archives at http://www.meteorite-list-archives.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com https://pairlist3.pair.net/mailman/listinfo/meteorite-list
[meteorite-list] Morocco's stone rush: Hunting meteorites is big business for nomads
http://www.middleeasteye.net/in-depth/features/rush-rare-stones-morocco-1695033044 Regards! Tom __ Visit our Facebook page https://www.facebook.com/meteoritecentral and the Archives at http://www.meteorite-list-archives.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com https://pairlist3.pair.net/mailman/listinfo/meteorite-list
