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Space News Update — October 2, 2015 —

Contents

In the News

Story 1: Charon takes center stage in new batch of New Horizons images

Story 2: Scientists Tantalized as Dawn Yields Global Mineral and Topographic Maps of

Ceres

Story 3: Rosetta's First Peek at the Comet's Dark Side

Departments

The Night Sky

ISS Sighting Opportunities

Space Calendar

NASA-TV Highlights

Food for Thought

Space Image of the Week

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1. Charon takes center stage in new batch of New Horizons images

With a meandering canyon system four times as long, and twice as deep, as the Grand Canyon in the American Southwest, the crust of Pluto’s moon Charon may have been shaped by violent eruptions and complicated geology once thought improbable for such a small body in the far depths of the solar system, scientists said Thursday.

Two-and-a-half months on from its historic first-ever encounter with Pluto on July 14, NASA’s New Horizons spacecraft is beaming home bits of data and imagery a little at a time, its radio link with Earth strained by the probe’s location 3.1 billion miles away.

The latest pictures released Thursday illustrate Charon as a complex world covered in ridges, canyons, mountains and different colors, with a noticeable change in terrain between the moon’s northern and southern hemispheres.

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Said Ross Beyer, an affiliate of the New Horizons geology team from the SETI Institute and NASA’s Ames Research Center: “We thought the probability of seeing such interesting features on this satellite of a world at the far edge of our solar system was low, but I couldn’t be more delighted with what we see!”

Although Charon is relatively modest in size — just slightly bigger than Ceres, the largest object in the asteroid belt — it has more than half the diameter of its companion Pluto. The similar sizes make Pluto and Charon a binary planet, where they move around each other in a wobbly 6.4-day orbit centered on a point in space just outside Pluto.

Many scientists expected Charon to be dull, gray and pockmarked with craters like the moon, but the story is changing.

Images released Thursday by NASA are the best views yet of Charon — even sharper views are still to come — and show a network of canyons and crevasses just north of the moon’s equator. Scientists say the chasms stretch more than 1,000 miles across the face of Charon observed by New Horizons during its July flyby, and apparently wraps around to the unseen far side of the frozen world.

“Four times as long as the Grand Canyon, and twice as deep in places, these faults and canyons indicate a titanic geological upheaval in Charon’s past,” NASA said in a press release.

The New Horizons spacecraft downlinked the pictures showing the canyon system Sept. 21. The images were captured just before the probe’s closest approach to Charon.

“It looks like the entire crust of Charon has been split open,” said John Spencer, deputy lead for the mission’s geology, geophysics and imaging team at the Southwest Research Institute in Boulder, Colorado. “In respect to its size relative to Charon, this feature is much like the vast Valles Marineris canyon system on Mars.”

Farther to the south, the rugged canyon lands give way to a smooth plain informally dubbed Vulcan Planum. Geologists say the region appears to be younger than the terrain to the north, a sign that something resurfaced that part of Charon more recently.

“The team is discussing the possibility that an internal water ocean could have frozen long ago, and the resulting volume change could have led to Charon cracking open, allowing water-based lavas to reach the surface at that time,” said Paul Schenk, a New Horizons team member from the Lunar and Planetary Institute in Houston.

The eruptions could have spewed material across Charon’s landscapes, refreezing to cover up ancient craters and other features now more prevalent in the northern hemisphere.

Source: Spaceflight Now Return to Contents

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2. Scientists Tantalized as Dawn Yields Global Mineral and Topographic Maps of Ceres

Slowly but surely the mysteries of dwarf planet Ceres are being peeled back layer by layer as NASA’s Dawn spacecraft orbits lower and lower and gathers detailed measurements that have now yielded global mineral and topographic maps, tantalizing researchers with the best resolution ever.

The Dawn science team has been painstakingly stitching together the spectral and imaging products captured from the lowest orbit yet achieved into high resolution global maps of Ceres, released today Sept. 30, by NASA.

“Ceres continues to amaze, yet puzzle us, as we examine our multitude of images, spectra and now energetic particle bursts,” said Chris Russell, Dawn principal investigator at the University of California, Los Angeles, in a statement.

The color coded map above is providing researchers with valuable insights into the mineral composition of Ceres surface, as well as the relative ages of the surface features that were a near total mystery until Dawn arrived on March 6, 2015.

The false-color mineral map view combines images taken using infrared (920 nanometers), red (750 nanometers) and blue (440 nanometers) spectral filters.

“Redder colors indicate places on Ceres’ surface that reflect light strongly in the infrared, while bluish colors indicate enhanced reflectivity at short (bluer) wavelengths; green indicates places where albedo, or overall brightness, is strongly enhanced,” say officials.

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“Scientists use this technique in order to highlight subtle color differences across Ceres, which would appear fairly uniform in natural color. This can provide valuable insights into the mineral composition of the surface, as well as the relative ages of surface features.”

Researchers say the mineral variations at Ceres “are more subtle than on Vesta, Dawn’s previous port of call.”

The asteroid Vesta was Dawn’s first orbital target and conducted extensive observations of the bizarre world for over a year in 2011 and 2012.

The Dawn team is meeting this week to review and publish the mission results so far at the European Planetary Science Conference in Nantes, France.

Dawn is Earth’s first probe in human history to explore any dwarf planet, the first to explore Ceres up close and the first to orbit two celestial bodies.

Ceres is a Texas-sized world, ranks as the largest object in the main asteroid belt between Mars and Jupiter, and may have a subsurface ocean of liquid water that could be hospitable to life.

The newly released maps were created from data gathered at Dawn’s current science orbit, known as the High Altitude Mapping Orbit (HAMO) phase of the mission, during August and September.

At HAMO, Dawn is circling Ceres at an altitude of barely 915 miles (1,470 kilometers) above the heavily cratered surface.

“Dawn arrived in this third mapping orbit [HAMO] on Aug. 13. It began this third mapping phase on schedule on Aug. 17,” Dr. Marc Rayman, Dawn’s chief engineer and mission director based at NASA’s Jet Propulsion Laboratory, Pasadena, California, told Universe Today.

Each HAMO mapping orbit cycle lasts 11 days and consists of 14 orbits lasting 19 hours each. Ceres is entirely mapped during each of the 6 cycles. The third mapping cycle started on Sept. 9.

Dawn’ instruments, including the Framing Camera and Visible and Infrared Spectrometer (VIR) will be aimed at slightly different angles in each mapping cycle allowing the team to generate stereo views and construct 3-D maps.

“The emphasis during HAMO is to get good stereo data on the elevations of the surface topography and to get good high resolution clear and color data with the framing camera,” Russell told me.

“We are hoping to get lots of VIR IR data to help understand the composition of the surface better.”

“Dawn will use the color filters in its framing camera to record the sights in visible and infrared wavelengths,” notes Rayman.

The new maps at HAMO provide about three times better resolution than the images captured from its previous orbit in June, and nearly 10 times better than in the spacecraft’s initial orbit at Ceres in April and May.

The science team also released a new color-coded topographic map annotated with over a dozen Cerean feature names recently approved by the IAU.

“The names for features on Ceres are all eponymous for agricultural spirits, deities and festivals from cultures around the world. These include Jaja, after the Abkhazian harvest goddess, and Ernutet, after the cobra-

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headed Egyptian harvest goddess. A 12-mile (20-kilometer) diameter mountain near Ceres’ north pole is now called Ysolo Mons, for an Albanian festival that marks the first day of the eggplant harvest.”

The biggest Cerean mystery of all remains the nature of the bright spots at Occator crater. It’s still under analysis and the team released a new color coded topographic map.

The imagery and other science data may point to evaporation of salty water as the source of the bright spots.

“Occasional water leakage on to the surface could leave salt there as the water would sublime,” Russell told me.

“The big picture that is emerging is that Ceres fills a unique niche,” Prof. Chris Russell, Dawn principal investigator told Universe Today exclusively.

“Ceres fills a unique niche between the cold icy bodies of the outer solar system, with their rock hard icy surfaces, and the water planets Mars and Earth that can support ice and water on their surfaces,” said Russell.

“The irregular shapes of craters on Ceres are especially interesting, resembling craters we see on Saturn’s icy moon Rhea,” says Carol Raymond, Dawn’s deputy principal investigator based at NASA’s Jet Propulsion Laboratory, Pasadena, California. “They are very different from the bowl-shaped craters on Vesta.”

Source: Universe Today Return to Contents

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3. Rosetta's First Peek at the Comet's Dark Side

Since its arrival at comet 67P/Churyumov-Gerasimenko, the European Space Agency's Rosetta spacecraft has been surveying the surface and the environment of this curiously shaped body. But for a long time, a portion of the nucleus -- the dark, cold regions around the comet's south pole -- remained inaccessible to almost all instruments on the spacecraft.

Due to a combination of its double-lobed shape and the inclination of its rotation axis, Rosetta's comet has a very peculiar seasonal pattern over its 6.5-year-long orbit. Seasons are distributed very unevenly between the two hemispheres. Each hemisphere comprise parts of both comet lobes and the "neck."

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For most of the comet's orbit, the northern hemisphere experiences a very long summer, lasting over 5.5 years, while the southern hemisphere undergoes a long, dark and cold winter. However, a few months before the comet reaches perihelion -- the closest point to the sun along its orbit -- the situation changes, and the southern hemisphere transitions to a brief and very hot summer.

When Rosetta arrived at 67P/C-G in August 2014, the comet was still experiencing its long summer in the northern hemisphere, and regions on the southern hemisphere received very little sunlight. Moreover, a large part of this hemisphere, close to the comet's south pole, was in polar night and had been in total darkness for almost five years.

With no direct illumination from the sun, these regions could not be imaged with Rosetta's OSIRIS (the Optical, Spectroscopic, and Infrared Remote Imaging System) science camera, or its Visible, InfraRed and Thermal Imaging Spectrometer (VIRTIS). For the first several months after Rosetta's arrival at the comet, only one instrument on the spacecraft could observe and characterize the cold southern pole of 67P/C-G: the Microwave Instrument for Rosetta Orbiter (MIRO).

In a paper accepted for publication in the journal Astronomy and Astrophysics, scientists report on the data collected by MIRO over these regions between August and October 2014.

"We observed the 'dark side' of the comet with MIRO on many occasions after Rosetta's arrival at 67P/C-G, and these unique data are telling us something very intriguing about the material just below its surface," said Mathieu Choukroun from NASA's Jet Propulsion Laboratory (JPL), Pasadena, California, lead author of the study.

Observing the comet's southern polar regions, Choukroun and colleagues found significant differences between the data collected with MIRO's millimeter and sub-millimeter wavelength channels. These differences might point to the presence of large amounts of ice within the first few tens of centimeters below the surface of these regions.

"Surprisingly, the thermal and electrical properties around the comet's south pole are quite different than what is found elsewhere on the nucleus," said Choukroun. "It appears that either the surface material or the material that's a few tens of centimeters below it is extremely transparent, and could consist mostly of water ice or carbon-dioxide ice."

The difference between the surface and subsurface composition of this part of the nucleus and that found elsewhere might originate in the comet's peculiar cycle of seasons. One of the possible explanations is that water and other gases that were released during the comet's previous perihelion, when the southern hemisphere was the most illuminated portion of the nucleus. The water condensed again and precipitated on the surface after the season changed and the southern hemisphere plunged again into its long and cold winter.

These are, however, preliminary results, because the analysis depends on the detailed shape of the nucleus. At the time the measurements were made, the shape of the dark, polar region was not known with great accuracy.

"We plan to revisit the MIRO data using an updated version of the shape model, to verify these early results and refine the interpretation of the measurements," added Choukroun.

Rosetta scientists will be testing these and other possible scenarios using data that were collected in the subsequent months, leading to the comet's perihelion, which took place on Aug. 13, 2015 and beyond.

Source: JPL Return to Contents

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The Night Sky Friday, October 2

After dark, look just above the northeast horizon — far below Cassiopeia — for bright Capella on the rise. How soon Capella rises, and how high you'll find it, depend on your latitude. The farther north you are, the sooner and higher.

Saturday, October 3

By about 11 or midnight, the waning Moon rises in the east-northeast. To its right in the east, Orion is also rising. The first bright star you hit looking to the right from the Moon is Betelgeuse: Orion's orange shoulder.

Sunday, October 4

Last-quarter Moon (exact at 5:06 p.m. Eastern Daylight Time). The Moon rises around midnight tonight, just beneath the horizontal stick figures of Gemini (for North America).

Monday, October 5

Look low in the southeast at nightfall for Fomalhaut coming up. It passes highest in the south about 11 p.m.

Tuesday, October 6

Vesta, the brightest asteroid, is still magnitude 6.2 a week past its opposition. It's easy in binoculars in western Cetus, especially now that the Moon has gone. Use the finder charts in the September Sky & Telescope, pages 48–49.

Uranus, magnitude 5.7, is also nearby! Finder chart.

Source: Sky & Telescope Return to Contents

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ISS Sighting Opportunities

For Denver: Date Visible Max Height Appears Disappears

Fri Oct 2, 8:38 PM 1 min 23° 10 above SW 23 above SW

Sat Oct 3, 7:46 PM 4 min 46° 11 above SSW 32 above E

Sun Oct 4, 6:58 PM 2 min 20° 20 above ESE 10 above ENE

Sun Oct 4, 8:32 PM 1 min 36° 24 above W 36 above NNW

Mon Oct 5, 7:39 PM 4 min 66° 23 above WSW 18 above NE

Tue Oct 6, 8:25 PM 2 min 20° 17 above NW 19 above N

Sighting information for other cities can be found at NASA’s Satellite Sighting Information

NASA-TV Highlights (all times Eastern Daylight Time)

10 a.m., Monday, October 5 - ISS Expedition 45 In-Flight Educational Event with the Robinson Secondary School in Fairfax, Virginia and ISS Commander Scott Kelly with Flight Engineers Kjell Lindgren of NASA and Kimiya Yui of JAXA (starts at 10:20 p.m.) (all channels)

Watch NASA TV on the Net by going to the NASA website. Return to Contents

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Space Calendar • Oct 02 - [Sep 26] MEXSAT 2 (Morelos 3) Atlas 5 Launch • Oct 02 - Moon Occults Aldebaran • Oct 02 - Comet 61P/Shajn-Schaldach Perihelion (2.114 AU) • Oct 02 - Asteroid 15 Eunomia At Opposition (7.4 Magnitude) • Oct 02 - Apollo Asteroid 2000 SM10 Near-Earth Flyby (0.030 AU) • Oct 02 - Asteroid 6563 Steinheim Closest Approach To Earth (1.281 AU) • Oct 02 - Asteroid 8275 Inca Closest Approach To Earth (1.349 AU) • Oct 02 - Giuseppe (Bepi) Colombo's 95th Birthday (1920) • Oct 03 - Comet 88P/Howell Closest Approach To Earth (1.337 AU) • Oct 03 - Apollo Asteroid 2015 SR Near-Earth Flyby (0.038 AU) • Oct 03 - Apollo Asteroid 2012 CL19 Near-Earth Flyby (0.045 AU) • Oct 03 - Apollo Asteroid 2009 DB43 Near-Earth Flyby (0.070 AU) • Oct 03 - 30th Anniversary (1985), STS-51-J Launch (Space Shuttle Atlantis, DOD) • Oct 03 - Walter Alvarez's 75th Birthday (1940) • Oct 03 - Charles Duke's 80th Birthday (1935) • Oct 04 - Soyuz TMA-18M Soyuz-FG Launch (International Space Station) • Oct 04 - Comet C/2014 W5 (Lemmon-PANSTARRS) At Opposition (2.108 AU) • Oct 04 - Comet 33P/Daniel Closest Approach To Earth (2.319 AU) • Oct 04 - Comet 117P/Helin-Roman-Alu Closest Approach To Earth (2.940 AU) • Oct 04 - Apollo Asteroid 2015 FS332 Near Earth Flyby (0.048 AU) • Oct 04 - Asteroid 149244 Kriegh Closest Approach To Earth (1.313 AU) • Oct 04 - Asteroid 1284 Latvia Closest Approach To Earth (1.340 AU) • Oct 04 - Asteroid 128036 Rafaelnadal Closest Approach To Earth (1.637 AU) • Oct 04 - Viktor Knorre's 175th Birthday (1840) • Oct 04 - Eustachio Divini's 405th Birthday (1610)

• Oct 04-10 - [Sep 27] World Space Week • Oct 05 - Jilin 1A/1B/1C CZ-2D Launch • Oct 05 - Cassini, Orbital Trim Maneuver #423 (OTM-423) • Oct 05 - Amor Asteroid 2009 TK Near-Earth Flyby (0.045 AU) • Oct 05 - Pavel Popovich's 85th Birthday (1930) • Oct 05 - Paul Wild's 90th Birthday (1925) • Oct 06 - Comet 205P-B/Giacobini Perihelion (1.540 AU) • Oct 06 - Kuiper Belt Object 2008 ST291 At Opposition (58.708 AU) • Oct 06 - 25th Anniversary (1990), STS-41 Launch (Space Shuttle Discovery, Ulysses Deployment) • Oct 06 - David Brin's 65th Birthday (1950) • Oct 06 - Jorgen Christensen-Dalsgaard's 65th Birthday (1950) • Oct 06 - Jesse Ramsden's 280th Birthday (1735)

Source: JPL Space Calendar Return to Contents

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Food for Thought

Rock samples from Western US teach how to hunt for life on Mars

The search for life beyond Earth is one of the grandest endeavors in the history of humankind -- a quest that could transform our understanding of our universe both scientifically and spiritually.

With news coming this week that NASA has confirmed the presence of flowing saltwater on the surface of Mars, the hunt for life on the Red Planet has new momentum.

"One of the many reasons this is exciting is that life as we currently know it requires water," said Alison Olcott-Marshall, assistant professor of geology at the University of Kansas. "So the fact that it's present at Mars means that the most basic and universal requirement for life was fulfilled."

In the journal Astrobiology, Olcott-Marshall recently has published an analysis of Eocene rocks found in the Green River Formation, a lake system extending over parts of Colorado, Utah and Wyoming.

Marshall and co-author Nicholas A. Cestari, a masters student in her lab, found these Green River rocks have features that visually indicate the presence of life, and they argue that probes to Mars should identify similar

indicators on that planet and double-check them through chemical analysis.

"Once something is launched into space, it becomes much harder to do tweaks -- not impossible, but much, much harder," Olcott-Marshall said. "Scientists are still debating the results of some of the life-detection experiments that flew to Mars on the Viking Missions in the late '70s, in a large part because of how the experiments were designed. Looking at Earth-based analogs lets us get some of these bumps smoothed out here on Earth, when we can revise, replicate and re-run experiments easily."

The researchers examined cored samples of rock from 50 million years ago that included sections of "microbial mats."

"Microbial mats are essentially the microbial world's version of apartment buildings -- they are layered communities of microbes, and each layer represents a different metabolic strategy," Olcott-Marshall said. "Generally, the photosynthetic microbes are at the top, and then every successive layer makes use of the waste products of the level above. Thus, not only does a microbial mat contain a great deal of biology, but a great number of chemicals, pigments and metabolic products are made, which means lots of potential biosignatures."

At times during the Eocene, the Green River Formation's water chemistry purged fish and other organisms from the lake, providing room for these microbes to thrive.

"During these times, 'microbialites' formed -- these are rocks thought to be made by microbial processes, essentially the preserved remnants of microbial mats. The Green River Formation has a wide variety of these structures, and these features are why we went looking in these rocks, as microbialites are one life-detection target on Mars."

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First, the researchers visually inspected the cored samples for signs of biology by identifying geological signs associated with microbialites -- such as "stromatolites."

"These are things like finely laminated sediments, where each lamination follows the ones below, or signs of cohesive sediment, things like layers that roll over onto themselves or are at an angle steeper than what gravity would allow," Olcott-Marshall said. "These are all thought to be signs that microbes are helping hold sediment together."

If visual examination pointed to the presence of biology in sections of the rock cores, the researchers looked to confirm the presence of life. They powdered those rock samples in a ball mill, and then used hot organic solvents like methanol to remove any organic carbons that might have been preserved in the rocks. That solvent was then concentrated and analyzed with gas chromatography/mass spectroscopy.

"GC/MS allows an identification of compounds, including organic molecules, preserved in a rock," Olcott-Marshall said. "Viking was the first time that a GC/MS was sent to Mars, and there is one up there right now on Curiosity collecting data."

Through GC/MS, the researchers determined that rock structures appearing to be biological indeed hosted living organisms millions of years ago: analysis showed the presence of lipid biomarkers.

"A lipid biomarker is the preserved remnant of a lipid, or a fat, once synthesized by an organism," Olcott-Marshall said. "These can be simple or very complex. Different organisms make different lipids, so identifying the biomarker can often allow a deeper understanding of the biota or the environment present when a rock was formed. These are a type of biosignature."

The researchers said their results could be a powerful guide for sample selection on Mars.

"There is a GC/MS on Curiosity right now, but there are only nine sample cups dedicated for looking for biomarkers like these," Olcott-Marshall said. "It's crucial those nine samples are ones most likely to guarantee success.

Additionally, one of the goals of the planned 2020 rover mission is to identify samples for caching for eventual return to Earth. The amount of sample that can be returned is likely very small, thus, once again, doing our best to guarantee success is very important. What this shows is that we can use visual inspection to help us screen for these samples that are likely to be successful for further biosignature analysis."

She said microbial and non-microbial rocks are found in similar environments, with identical preservation histories for millions of years, and many of the same chemical parameters, such as amounts of organic carbon preserved in the rocks.

"The only difference is that one rock is shaped in a way people have associated with biology, and sure enough, those rocks are the ones that seem to preserve the biosignatures, at least in the Green River," she said.

Source: Eureka Alert Return to Contents

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Space Image of the Week

Hubble Zooms in on the Veil Nebula

Not long before the dawn of recorded human history, our distant ancestors would have witnessed what appeared to be a bright new star briefly blazing in the northern sky, rivaling the glow of our moon. In fact, it was the titanic detonation of a bloated star much more massive than our sun. Now, thousands of years later, the expanding remnant of that blast can be seen as the Cygnus Loop, a donut-shaped nebula that is six times the apparent diameter of the full moon. The Hubble Space Telescope was used to zoom into a small portion of that remnant, called the Veil Nebula. Hubble resolves tangled rope-like filaments of glowing gases. Supernovae enrich space with heavier elements used in the formation of future stars and planets — and possibly life.

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Source: HubbleSite Return to Contents