Across the Universe: Where’s the olivine?
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This column first ran in The Tablet in July 2014 It was a beautiful theory, while it lasted. Most meteorites are well-compressed lumps of primordial dust and little beads of rock. But some are chips of lava, bits of some small asteroid that melted and sorted itself into a small iron core and a crust of frozen basaltic lava. We’ve even seen one such asteroid: the spectra colors of Vesta (the brightest, and second-biggest, of the asteroids) uniquely match these basaltic meteorites [in particular, the Howardite-Eucrite-Diogenite meteorites known familiarly as the HED meteorites]. When a mixture of various minerals gets hot, as inside a volcano, only some of those minerals melt; they make the lava that erupts to the surface, leaving behind other unmolten minerals deep below the volcano. These meteorite lavas should behave the same way. During my student days in the 1970s, we calculated that that for every basaltic meteorite, there should be about four times as much … Continue reading

Spacecraft 3D: NASA’s Augmented Reality Smartphone App
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NASA has an app for smartphones that lets you learn about and interact with several different spacecraft that explore our solar system, study the Earth, and observe the cosmos. You can hold a virtual Mars rover in the palm of your hand, or watch as a rocket’s boosters fall away, and its fairing separate! Seeing the Curiosity rover popup in my hand, and being able to rotate it, zoom, and deploy its mast – using my Android – just blew me away! I think students would LOVE this! If you have an iOS/Android phone,download Spacecraft 3D now and experience #AugmentedReality! https://t.co/gPQPe62z6k pic.twitter.com/8RuPfOZktS — : NASA_Eyes (@nasa_eyes) December 8, 2016 A photo target must be used for the app to generate the spacecraft model; the photo can be small enough to fit in your hand, or printed larger for use on a tabletop. The app can email you a link to the AR target (http://www.jpl.nasa.gov/apps/images/3dtarget.pdf) which includes some cool Mars pics … Continue reading

Across the Universe: Dawn of My Belief
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This column first ran in The Tablet in June 2011 As a graduate student in 1976 I gave a paper to the Meteoritical Society about a theory that I (and my thesis advisor) had developed concerning a rare class of meteorites which appeared to be bits of lava from the surface of an asteroid. While most asteroids are collections of metal and rock, we knew that some of them must have melted; for one, asteroid Vesta’s infrared colors exactly matched the spectra of these basaltic meteorites. Our work determined that for every gram of lava in these meteorites, there should have been another nine grams of residue in its parent asteroid. After my talk, a grand old man of the field approached me. “If these meteorites come from an melted asteroid,” he asked, “lavas flowing to the top and residue in the center, then once it was broken into meteorites, shouldn’t we have we seen nine times as many meteorites from … Continue reading

Dawn Probe to Remain in Ceres Orbit
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NASA’s Dawn spacecraft has completed its primary mission – to explore the two most massive bodies in the main asteroid belt: asteroid 4 Vesta, and dwarf planet Ceres. After a recent mission extension, Dawn will continue studying Ceres – essentially becoming a long-term reconnaissance orbiter. Extended missions approved for @NASA_Dawn, Mars orbiters, @LRO_NASA, @NASANewHorizons, more: https://t.co/vPXmOYGjW5 pic.twitter.com/Qrzcyeg8zP — NASA Solar System (@NASASolarSystem) July 1, 2016 One of the advantages of long-term observations is seeing changes that occur over time, as with the seasonally recurring slope lineae on Mars, and fresh impact craters on both the Moon and Mars. There was a brief period of confusion on various social media sites, as rumors that Dawn was possibly going to leave Ceres and fly-by asteroid 145 Adeona, but Jim Green, NASA’s Director of Planetary Science, noted that long-term monitoring of Ceres had more of a potential for significant scientific discoveries than a flyby of Adeona. Scientists have found permanently shadowed craters on Ceres; … Continue reading

Dawn Mapping of Ceres Continues
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The Dawn mission as almost completely mapped the surface of dwarf planet Ceres at a resolution of 35 meters (120 feet) per pixel – far surpassing the original objective of imaging 80% percent of Ceres’ surface at a resolution of 200 meters (660 feet) per pixel. From the Dawn Blog: “Since April 11, instead of photographing the scenery directly beneath it, Dawn has been aiming its camera to the left and forward as it orbits and Ceres rotates. By May 25, it will have mapped most of the globe from that angle. Then it will start all over once more, looking instead to the right and forward from May 27 through July 10. The different perspectives on the terrain make stereo views, which scientists can combine to bring out the full three dimensionality of the alien world.” Dawn is using its gamma ray and neutron detector (GRaND) to reveal the atomic composition of Ceres’ crust to a depth of about a … Continue reading

Across the Universe: Touch the Sky
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This column first ran in The Tablet in April, 2010 Next summer [2011], the “Dawn” spacecraft will go into orbit around Ceres and Vesta, biggest and brightest of the asteroids. (Indeed they are so much larger than the other asteroids that they may be better classified as dwarf planets.) These bodies have been well studied by telescope for more than 200 years – Ceres was discovered on New Year’s Day, 1801, by the Sicilian priest-astronomer Giuseppe Piazzi – but seeing them remotely is nothing like getting a close-up view. [In April of 2010], a team of scientists and engineers met in Rome to prepare for Dawn’s arrival, and they spent a morning visiting our observatory in Castel Gandolfo. For reasons ranging from the way they reflect infrared light to the conclusions of computer models for their chemical evolution (including work I was involved with more than thirty years ago), we believe that certain meteorites in our collections are actual samples of … Continue reading

Bright Spot on Ceres in Hi-Rez
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The Dawn mission team has produced this high-resolution enhanced-color image of the bright spots in Occator crater on Ceres. In the crater’s center, the close-up reveals a fractured dome surrounded by a smooth-walled pit. The image above was created by combining high-resolution images of Occator crater obtained in February 2016, with color images obtained in September 2015. Color images were taken using 438, 550 and 965 nanometer filters (the latter in the near-infrared, and slightly beyond the range of human vision). Compare that with the image below, taken during Dawn’s approach to Ceres in early 2015; at that time, the spots were all over the news as “The Mysterious Bright Spots.” The bright spots on Ceres are best explained as the result of briny water erupting from Ceres’ interior, and then sublimating away into space, leaving behind salty deposits and ammonia-rich clays. More Info: Dawn Mission Page Also in The Dawn Misson to the Asteroid Belt Dawn Mission Sees Dwarf … Continue reading

Color Topography of Ahuna Mons on Ceres
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The Dawn mission team as released colorized topographic views of the region around Ahuna Mons, a mysterious conical mountain on Ceres. Both views were created using images taken at an orbital distance of about 385 km (240 mi) above the surface, with a resolution of about 35 m (120 ft) per pixel. The elevations span a range of about 9 km (5.5 mi) from the lowest places (blue) to the highest terrains (brown). The side perspective view (below) was created by draping image mosaics over a shape model. Congratulations to the Dawn mission team for winning not one but TWO awards! National Aeronautic Association Robert J. Collier Trophy, presented annually “for the greatest achievement in aeronautics or astronautics in America, with respect to improving the performance, efficiency and safety of air or space vehicles.” National Space Club and Foundation’s Nelson P. Jackson Award, presented annually for “a significant contribution to the missile, aircraft or space field.” More Info: Dawn Mission … Continue reading

Images from Dawn’s Low Altitude Mapping Orbit
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NASA’s Dawn spacecraft recently reached its lowest altitude orbit over dwarf planet Ceres, and has been returning images of craters on Ceres with a network of cracks, bright material exposed on crater rims, and in spots all over the surface, and rough cratered terrain everywhere. The Dawn spacecraft has returned more than 16,000 pictures of Ceres in 2015, including more than 2,000 since descending to its low orbit in December 2015. January 1, 2016 is the 215th anniversary of Giuseppe Piazzi’s discovery of Ceres. More: New Details On Ceres Seen in Dawn Images Dawn Blog Also in The Dawn Misson to the Asteroid Belt Dawn Mission Sees Dwarf Planet Ceres Rotating Dawn Images of Ceres now Better Than the Hubble Space Telescope Dawn Inches Ever Closer to Ceres Ceres Ever Closer Ceres to Capture Dawn Today Where are all the new images of Ceres? Just a Sliver of Ceres Dawn Spies Ceres’ North Pole Ceres from Dawn’s RC3 Orbit Cratered … Continue reading

Ceres South Polar Region
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The Dawn spacecraft is orbiting Ceres at its final altitude of 385 km (240 mi). The Dawn Twitter feed has been awash recently with images of the surface of the dwarf planet. The image above shows an area near Ceres’ south polar region. The shadows appear elongated because from this perspective, so close to Ceres’ south pole, the sun is never very high in the sky. On Dec. 18, 2015, the Dawn twitter feed posted that the spacecraft had begun intensive observations of Ceres. Update: Today I begin my intensive observations of #Ceres at this lowest altitude (~240 mi) pic.twitter.com/yUWFsPaxj9 — NASA's Dawn Mission (@NASA_Dawn) December 18, 2015 Today, on the final day of 2015, the Dawn Twitter feed posted a video showing some of the amazing images the Dawn spacecraft has returned from Ceres over the past year. I've had an amazing first year at #Ceres! Some photos of my journey: pic.twitter.com/g3z1SMRBF7 — NASA's Dawn Mission (@NASA_Dawn) December 31, … Continue reading

Pickled Ceres
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The Dawn spacecraft has reached its Low Altitude Mapping Orbit (LAMO) above dwarf planet Ceres, and is preparing for new observations with its gamma ray and neutron detector (GRaND). Energies and numbers of these two components of nuclear radiation will be measured using this instrument on December 18th; scientists will use this data to determine the abundances of some elements on Ceres. In the days before the GRaND observations start, Dawn will take more photographs of Ceres, and do some infrared spectroscopy. I have reached my final orbital altitude! 240 mi (385 km) from #Ceres pic.twitter.com/yUWFsPaxj9 https://t.co/sfBXnsQZPq — NASA's Dawn Mission (@NASA_Dawn) December 9, 2015 In the image below, Occator Crater, containing the brightest area on Ceres, is shown inset at top left; Oxo Crater, the second-brightest feature on Ceres, is at the top right. Diffuse hazes were identified at both Occator and Oxo craters; these hazes appear when the sun shines on these craters, likely from the sublimation of … Continue reading

Dawn Mission High Altitude Mapping Orbit Complete
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NASA’s Dawn Mission has completed its High Altitude Mapping Orbit (HAMO) survey mission of dwarf planet Ceres, and is sending data back to Earth. The Dawn Twitter feed posts announcements and new images frequently. I have completed my #Ceres mapping campaign at my current altitude! Beaming data back now; will start descending later this week. — NASA’s Dawn Mission (@NASA_Dawn) October 21, 2015 Later this year, the spacecraft it will spiral down from it’s current altitude of 1,470 km (915 mi) to its fourth and final orbital altitude at about 375 km (230 mi) above Ceres; it will take two months to descend to this new Low Altitude Mapping Orbit (LAMO). Once at its LAMO, Dawn will record spectra of visible & infrared light, neutrons & gamma rays, and measure the distribution of mass inside Ceres. And take pictures… lots and LOTS of pictures. Maybe then, we’ll finally know what those bright spots in Occator crater are. Next year, the … Continue reading