Grand Finale – Painting inspired by the Cassini Mission to Saturn
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Also in Exploring the Solar System Exploring the Solar System: The Mass of the Sun Marvellous Mars Drawing Workshop at Dunsink Observatory Dublin Astronomical Sketching – Education in action Stars Wonderful Stars at Wexford Town Library Ireland Get ready the Perseids are coming Space the final Frontier – World Space Week 2016 On the richness of the lunar surface Dark Sky Magic at Ballycroy National Park Mayo Ireland Grand Finale – Painting inspired by the Cassini Mission to Saturn View the entire series … Continue reading

Titan: Frozen Moon of Saturn
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It’s hard to believe that it’s been 12 years since the Huygens probe touched down on the surface of Saturn’s moon Titan – the only moon in the solar system with a dense atmosphere and clouds. The probe returned images of rugged terrain as it descended, and revealed what appears to be drainage channels flowing down to a possible shoreline. The lander returned data for about 90 minutes after touchdown. Huygens is the most distant landing of any human-made craft. The Huygens lander was part of the Cassini mission to Saturn; the mission was so successful, it was extended in 2008, and again in 2010. The spacecraft has flown by numerous moons, and returned a treasure trove of scientific data; it has also returned some of the most spectacular imagery ever produced by a robotic probe. Cassini is now in its final months at Saturn, with the probe slated to burn up on Saturn’s atmosphere this September. From JPL Press Release 2017-006: 2005 Historic Descent … Continue reading

Cassini’s Final Months at Saturn
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NASA’s Cassini mission to Saturn is in its final months. The spacecraft has been put into a polar orbit which brings it over Saturn’s poles, and very close to the main rings. Cassini has sent back spectacular views of  Saturn’s north polar region shortly before it made its first close pass by the outer edge of Saturn’s main rings. In late April, Cassini will again change its orbit, bringing the spacecraft between Saturn’s innermost ring, and its cloudtops. These orbits send tingles through my spine when I think about them; there is a chance that a ring particle might impact the spacecraft, rendering it nonfunctional. According to NASA Eyes on the Solar System, when Cassini passes through the ring plane from now through April, it will be travelling at 21 km/sec. When it changes orbit in late April, and gets closer to Saturn, it will be passing over the cloudtops at about 34 km/sec. If Cassini survives all its passes … Continue reading

Venus and Mars in the Evening, Jupiter in the Morning
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Venus is low and bright, and Mars is high and dim in the southwestern sky after dusk. Jupiter is low in the predawn sky to the southeast. Venus orbits the Sun faster than the Earth, and as it catches up with the Earth over the next couple months, it will continue to appear higher in the evening sky. In mid-February, Venus will start to appear lower in the sky each evening, until it disappears into the glare of the Sun in early March. Venus will reappear in the predawn sky starting in early April. Mars will continue to dim as the Earth puts more distance between the two planets, until it disappears into the glare of the Sun in mid-April. Mars will reappear in the predawn skies in late September. Jupiter will be visible in the predawn skies for several months, slowly moving from east to west; it will appear high in the southern sky in January, and low in … Continue reading

Enceladus, Ocean World
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NASA’s Cassini mission scientists have determined that the slight wobble observed in Saturn’s moon Enceladus, as it orbits the ringed giant planet, is too large for the moon to be entirely frozen to its core. This wobble, referred to as a libration, reveals that the icy crust of Enceladus is disconnected from its rocky interior. In other words: Enceladus’ icy crust is sliding around on top of a global ocean of liquid water, and where there’s water, life may follow. This graphic (above) is an update to Enceladus: Possible Hydrothermal Activity (left), which showed only a regional sea beneath the south polar region of Enceladus. As Enceladus orbits Saturn, it is subject to tidal forces due to gravitation. These forces stretch the moon, causing friction, which heat up the moon’s interior. This is a process is called tidal heating. Jupiter’s moon Io is the most volcanically active body in the solar system, as a result of tidal heating. It was … Continue reading

Dione and Cassini
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“This view from NASA’s Cassini spacecraft looks toward Saturn’s icy moon Dione, with giant Saturn and its rings in the background, just prior to the mission’s final close approach to the moon on August 17, 2015. At lower right is the large, multi-ringed impact basin named Evander, which is about 220 miles (350 kilometers) wide. The canyons of Padua Chasma, features that form part of Dione’s bright, wispy terrain, reach into the darkness at left. Imaging scientists combined nine visible light (clear spectral filter) images to create this mosaic view: eight from the narrow-angle camera and one from the wide-angle camera, which fills in an area at lower left. The scene is an orthographic projection centered on terrain at 0.2 degrees north latitude, 179 degrees west longitude on Dione. An orthographic view is most like the view seen by a distant observer looking through a telescope. North on Dione is up. The view was acquired at distances ranging from approximately … Continue reading

Cassini Returns to a Near Equatorial Orbit Around Saturn
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A dual view of Saturn’s icy moon Rhea marks the return of NASA’s Cassini spacecraft to the realm of the planet’s icy satellites. This follows nearly two years during which the spacecraft’s orbits carried it high above the planet’s poles. Those paths limited the mission’s ability to encounter the moons, apart from regular flybys of Titan. Cassini’s orbit will remain nearly equatorial for the remainder of 2015, during which the spacecraft will have four close encounters with Titan, two with Dione and three with the geyser-moon, Enceladus. The two views of Rhea were taken about an hour-and-a-half apart on Feb. 9, 2015, when Cassini was about 30,000 to 50,000 miles (50,000 to 80,000 kilometers) away from the moon. Cassini officially began its new set of equatorial orbits on March 16. The views show an expanded range of colors from those visible to human eyes in order to highlight subtle color variations across Rhea’s surface. In natural color, the moon’s surface … Continue reading

Across the Universe: Fire and Ice
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Originally published in The Tablet in March, 2006. This year’s Lunar and Planetary Science Conference, held outside the Johnson Space Center in Houston, has been unusually rich. We saw fiery dust from an ice-rich comet; startling images from Mars; a new type of lunar rock… and that was just on Monday morning. By Friday afternoon, I was exhausted. I had already heard the Stardust results (see Across the Universe) at the Sunday welcome cocktail party when one of the mission scientists whispered to me, “We’ve found CAIs!” (Another friend on the team described Stardust Principle Scientist Don Brownlee’s first comment when they finally got the samples: “I can’t believe it actually worked!”) These high-temperature grains of Calcium and Aluminum oxides that appear as Inclusions in certain meteorites are thought to represent the first solid materials to crystallize out from the hot gases that made the sun and planets. How did they wind up wrapped in comet ices, stored in the … Continue reading

Titan’s Surface Imaged Using New Technique
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Radar images of Titan have always had a grainy appearance due to electronic noise. A new tool suppresses the noise, resulting in clearer views than ever before. During 10 years of discovery, NASA’s Cassini spacecraft has pulled back the smoggy veil that obscures the surface of Titan, Saturn’s largest moon. Cassini’s radar instrument has mapped almost half of the giant moon’s surface; revealed vast, desert-like expanses of sand dunes; and plumbed the depths of expansive hydrocarbon seas. What could make that scientific bounty even more amazing? Well, what if the radar images could look even better? Thanks to a recently developed technique for handling noise in Cassini’s radar images, these views now have a whole new look. The technique, referred to by its developers as “despeckling,” produces images of Titan’s surface that are much clearer and easier to look at than the views to which scientists and the public have grown accustomed. Typically, Cassini’s radar images have a characteristic grainy … Continue reading

Across the Universe: The best way to travel
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First published in The Tablet in January, 2007   Dark and dreary, January is a time to take off to new and exotic climes; or at least, to daydream about such trips. My own January voyage was a visit to my old hometown, snow-dusted Detroit, to attend a science fiction convention. But a panel discussion at that meeting, “Travel Destinations of the Solar System,” challenged us to imagine really exotic localities. Where among the planets would we love to go? And what it would be like to be standing there, in person? Panelist Bill Higgins, a radiation physicist at Fermi Lab in Chicago, regularly presents spaceflight results as a Nasa “Solar System Ambassador” at events like this. He described how Pluto and its moon Charon orbit each other while locked in a spin state that keeps each body always facing the other. “What if we could stretch a “beanstalk” across the 17,000 km gap between them?” he asked. “We could … Continue reading

Across the Universe: Desert or a dessert?
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First published in The Tablet in January, 2005, just after the Huygens probe landed on Saturn’s moon Titan. This text is based on what I submitted, which was edited for length when it was printed.   The most remarkable thing about the images from Saturn’s moon, Titan, which ESA’s Huygens probe has just sent us, is how “familiar” they look. They remind me of Nadar’s 19th century Collodion “wet plate” photographs taken from a balloon above Paris. Black and white, a bit fuzzy, these patterns of light and darkness can be grasped and processed by imagination and memory until we impose meaning on them. I picture myself floating through the clouds, gazing across at an intricate pattern of riverbeds cutting through rough light-colored mountains, flowing down to a flat, wine-dark sea. If these are riverbeds – and they certainly look like textbook examples of the many-branched “dendritic channels” made by rainfall flowing down hills on Earth – the fluid in them can’t have … Continue reading

Saturn: Beauty in Sight and Sound
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Created by stitching together over 30,000 photographs taken by the robotic Cassini spacecraft – No 3D models, CGI or texture maps used! Set to “Adagio for Strings” performed by the Greensboro Symphony Orchestra and conducted by Dmitry Sitkovetsky. This excerpt from the IMAX movie “In Saturn’s Rings” never fails to bring tears to my eyes due to its sheer beauty. Watch closely as the razor-thin rings momentarily vanishes as orbiter crosses the plane of their orbit. The Cassini orbiter was launched in October 1997, and entered orbit around Saturn on June 30, 2004. Its mission has been extended twice, and is currently scheduled to continue through September of 2017. Cassini has discovered plumes of water vapor pouring from its icy moon Enceladus, and discovered a new type of “Dusty Plasma” near Enceladus. Cassini landed a probe on Saturn’s largest moon, Titan, and has imaged hydrocarbon oceans and river-like structures there. Cassini has witnessed tiny shepherd moons within Saturn’s rings, and … Continue reading