11 Aug 2016

50th Anniversary of Lunar Orbiter 1 Mission

Today is the 50th anniversary of the launch of the first of five lunar orbiters that returned images of 99 percent of both the near- and far-side surfaces of the moon. The orbiters sent back a total of 3,062 photos.

Lunar_Orbiter_NASM_medLunar Orbiter 1, built by The Boeing Co., was launched Aug. 10, 1966 on an Atlas SLV-3 Agena-D rocket from Cape Canaveral in Florida. It was designed primarily to photograph smooth areas of the moon’s surface for selection of landing sites for the Surveyor and Apollo missions.

Radiation experiments on the orbiters also confirmed that the design of Apollo spacecraft hardware would protect astronauts from short-term exposure to solar particle events.

The orbiters were commanded to crash on the moon before their attitude control gas ran out so they would not be a navigational or communications hazard to Apollo flights.

The program was managed by NASA Langley Research Center in Hampton, Virginia.

Young stars in Sagittarius cluster excite astronomers

The star cluster Messier 18 and its surroundings

M18 – NGC 6613 | RA 18h 17m  DEC – 5 deg 09’ | Mag +7.5 | Size 7 arc minutes |

Ashampoo_Snap_2016.08.09_23h34m54s_001_Messier 18 was discovered and catalogued in 1764 by Charles Messier — for whom the Messier Objects are named — during his search for comet-like objects. It lies within the Milky Way, approximately 4600 light-years away in the constellation of Sagittarius, and consists of many sibling stars loosely bound together in what is known as an open cluster.

There are over 1000 known open star clusters within the Milky Way, with a wide range of properties, such as size and age, that provide astronomers with clues to how stars form, evolve and die. The main appeal of these clusters is that all of their stars are born together out of the same material.

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[Click on the images to enlarge]

In Messier 18 the blue and white colours of the stellar population indicate that the cluster’s stars are very young, probably only around 30 million years old. Being siblings means that any differences between the stars will only be due to their masses, and not their distance from Earth or the composition of the material they formed from. This makes clusters very useful in refining theories of star formation and evolution.

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Astronomers now know that most stars do form in groups, forged from the same cloud of gas that collapsed in on itself due to the attractive force of gravity. The cloud of leftover gas and dust — or molecular cloud — that envelops the new stars is often blown away by their strong stellar winds, weakening the gravitational shackles that bind them. Over time, loosely bound stellar siblings like those pictured here will often go their separate ways as interactions with other neighbouring stars or massive gas clouds nudge, or pull, the stars apart. Our own star, the Sun, was most likely once part of a cluster very much like Messier 18 until its companions were gradually distributed across the Milky Way.

The dark lanes that snake through this image are murky filaments of cosmic dust, blocking out the light from distant stars. The contrasting faint reddish clouds that seem to weave between the stars are composed of ionised hydrogen gas. The gas glows because young, extremely hot stars like these are emitting intense ultraviolet light which strips the surrounding gas of its electrons and causes it to emit the faint glow seen in this image. Given the right conditions, this material could one day collapse in on itself and provide the Milky Way with yet another brood of stars — a star formation process that may continue indefinitely.

This mammoth 30 577 x 20 108 pixel image was captured using the OmegaCAM camera, which is attached to the VLT Survey Telescope (VST) at ESO’s Paranal Observatory in Chile.

9 Aug 2016

Celebrate the Royal Greenwich Observatory

45 Years-ago the magnificent 28 inch refractor returned to the Royal Greenwich Observatory after a period of safe keeping. It was housed at Herstmonceux Castle for a while, then on 23 October 1971 Sir Patrick Moore was on hand to record the event for the BBC Sky at Night program.

In July I went back to the Royal Greenwich Observatory to meet the Curator Dr Louise Devoy, who was kind enough to show me around and learn something about the other telescopes their. Then I went over to see the 28 inch refractor itself. It is the 10th biggest refractor telescope in the world today, and the only one that visitors can look through on observational nights at Greenwich.

The Royal Greenwich Observatory was established in 1675 by King Charles II to find a means of measuring Longitude so mariners would not get lost at sea. The King appointed John Flamsteed as the first astronomer Royal.

The Cassini Solstice mission roles on as planet’s shadow shortens

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Turning a midsummer night's dream into reality, NASA's Cassini spacecraft began its new mission extension -- the Cassini Solstice Mission – in September 2010. The mission extension takes Cassini a few months past Saturn's northern summer solstice (or midsummer) through September 2017.

A complete seasonal period on Saturn has never been studied at this level of detail.

The shadow of Saturn on the rings, which stretched across all of the rings earlier in Cassini's mission (see PIA08362), now barely makes it past the Cassini division.

The changing length of the shadow marks the passing of the seasons on Saturn. As the planet nears its northern-hemisphere solstice in May 2017, the shadow will get even shorter. At solstice, the shadow's edge will be about 28,000 miles (45,000 kilometres) from the planet's surface, barely making it past the middle of the B ring.

The moon Mimas is a few pixels wide, near the lower left in this image.

This view looks toward the sunlit side of the rings from about 35 degrees above the ring plane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on May 21, 2016.

The view was obtained at a distance of approximately 2.0 million miles (3.2 million kilometres) from Saturn. Image scale is 120 miles (190 kilometres) per pixel.

8 Aug 2016

Rainer Weiss wins Kavli Prize in Astrophysics

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LIGO inventor shares award for direct detection of gravitational waves.

Rainer Weiss, emeritus professor of physics, is a recipient of the 2016 Kavli Prize in Astrophysics. The Kavli Prizes are awarded biennially to recognize scientists who have made seminal advances in three categories: astrophysics, nanoscience, and neuroscience.

Weiss will share the prize, including a cash award of $1 million, with Ronald Drever, emeritus professor of physics at Caltech, and Kip Thorne, Caltech’s Richard P. Feynman Professor of Theoretical Physics, emeritus. The three scientists, who are co-founders of the Laser Interferometer Gravitational-wave Observatory (LIGO), have received the prize for the direct detection of gravitational waves, according to the award citation:

“This detection has, in a single stroke and for the first time, validated Einstein’s General Theory of Relativity for very strong fields, established the nature of gravitational waves, demonstrated the existence of black holes with masses 30 times that of our sun, and opened a new window on the universe.”

On September 14, 2015, LIGO’s two interferometers — one in Washington, the other in Louisiana — picked up a signal that lasted just one-fifth of a second. For the next few months, LIGO scientists around the world would carefully analyse, verify, and verify again, to determine that this signal represented the first direct detection of gravitational waves — ripples across the universe, created by extreme cataclysmic events billions of years ago.

The scientists determined that the incredibly faint signal was produced by the spectacularly violent collision of two black holes, each about 30 times as massive as the sun, 1.3 billion light years away.

Announcing the Kavli Astrophysics recipients, in an address in Oslo, Norway, Mats Carlsson, chair of the astrophysics committee, read from the award citation:

“The detection of gravitational waves is an achievement for which hundreds of scientists, engineers, and technicians around the world share credit. Drever, Thorne, and Weiss stand out: Their ingenuity, inspiration, intellectual leadership, and tenacity were the driving force behind this epic discovery.”

Pushing for a signal

In 1972, Weiss had worked out the basic concept for an interferometer to detect gravitational waves — an idea he originally drew up as an exercise for students in his general relativity course at MIT. His concept would eventually serve as the essential blueprint for LIGO.

From LIGO’s earliest days to its most recent detection, “Weiss provided technical leadership and devoted his extraordinary experimental acumen over the next decades, contributing to every aspect of the final apparatus,” the citation reads.

In 1974, a research team led by physicists Russell Hulse and Joseph Taylor made the first detection of gravitational waves, by analysing the behaviour of two orbiting neutron stars — a detection for which the pair was awarded the Nobel Prize in physics in 1993. The detection, however, was not a direct one.

In 1975, Weiss and Thorne met for the first time at a NASA committee meeting in Washington, D.C., where they began to think about how Weiss’ interferometer design could be scaled up to make a direct detection of gravitational waves. Since the 1960s, Thorne had been evaluating how extreme events such as colliding black holes and neutron stars generate gravitational waves, and how those waves might be detected from Earth.

Weiss and Thorne pushed the concept of LIGO through numerous hurdles in funding and design, and eventually oversaw the observatory’s construction, in the form of two identical and massive instruments, each 4 kilometres long and 3,000 kilometres apart.

In 1979, Drever joined the team as the third co-founder of LIGO, and helped to perfect the design and operation of the interferometers, devising ways to increase the power and efficiency of the optical systems central to LIGO’s sensitivity.

“For the first time in history we can explore the universe’s mysteries in three regimes: electromagnetic, particle, and gravitational regime,” said France C√≥rdova, director of the National Science Foundation, who spoke as part of the awards announcement.

“Humming with signals”

Weiss received his BS in 1955 and his PhD in 1962, both from MIT. After appointments at Tufts University and Princeton University, Weiss returned to MIT as a faculty member in 1964. He has also served as an adjunct professor of physics at Louisiana State University since 2011. Weiss is a co-founder and science advisor of the NASA Cosmic Background Explorer (COBE) satellite mission, which measured the spectrum of cosmic microwave background radiation supporting the Big Bang scenario. 

Weiss has received numerous awards and honours, including the 2003 Medaille de l’ADION, the 2006 Gruber Prize in Cosmology, and the 2007 Einstein Prize of the American Physical Society. He is a fellow of the American Association for the Advancement of Science, the American Academy of Arts and Sciences, and the American Physical Society, as well as a member of the National Academy of Sciences. Earlier this year, Weiss received a Special Breakthrough Prize in Fundamental Physics and the 2016 Gruber Prize in Cosmology, both shared with Drever and Thorne. Most recently, the three co-founders were also awarded the Shaw Prize in Astronomy.

Today, Weiss and Thorne watched a live broadcast of the Kavli Prize announcement from New York, as part of the World Science Festival. As their names were announced, the pair, who are close friends, shared a hug, to a standing ovation.

In a panel held after the Kavli Prize announcement to discuss the significance of each Kavli Prize, Nergis Malvalvala, who is the Curtis and Kathleen Marble Professor of Astrophysics and associate head of the Department of Physics at MIT, a LIGO team member, and a former student of Weiss’, said of LIGO’s future: “We have so much still to do. We’ve really just uncovered the very first signal. The universe is humming with signals we have yet to pick up.”

7 Aug 2016

NASA peers inside a rocket plume imaged for the first time

You’ve never truly seen what a rocket plume looks like. They are extremely bright and therefore, have never been photographed properly and unless you want to stare directly into one, it’ll be nearly impossible to imagine. Although that’s difficult, considering there haven’t been cameras that could capture its image before.

However, NASA unveiled a new camera during its recent space launch test, which is able to show the detail in a rocket plume. And it looks pretty spectacular.

Normally cameras can’t properly capture something like a rocket plume. You can fiddle with the exposure settings, but reducing them darkens the rest of the image. Most cameras also only record one exposure at a time.

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However, the new High Dynamic Range Stereo X (HiDyRS-X) project overcomes this by being able to record multiple slow motion exposures at once and combining them into a more high-quality video. It uses a similar technique to what night photographers use when they splice multiple images together in post to get an impressive image.

The photo below is of the plume taken without the camera, so you can clearly see the difference.

Photo credit: NASA

According to a statement from NASA, scientists tried out the camera while testing its booster, QM-2. They monitored the camera from a safe distance, but its automatic timer failed to go off, meaning scientists had to start it manually.

And apparently, the force of the booster test was so great that it disconnected the camera’s power source. So NASA got confirmation that its camera works, but also that its rocket is very powerful.

Currently, this is just a prototype. Scientists plan to build a second one with more advanced capabilities, including with alignment. We’re looking forward to seeing more amazing photos, NASA! Don’t keep us waiting.

6 Aug 2016

Comet Panstarrs X1 is a spectacle in the celestial hare

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2016 July 24 18h04m UT, FLI PL16200, ASA 12" f/3.6. LRGB 8/4/4/4 min., Farm Tivoli, Namibia, Remote © 2016 Gerald Rhemann

panstars

Despite being rather faint, Mag 12, Panstarrs X1 is putting on a nice show for observers in the southern hemisphere. The comet is in the constellation of Hydra and lies close to the stat Pi Hydrae.

On 14 August the comet can be found at:

RA 14h 19m 52.7s DEC –29 53’ 08”

The above photograph was taken on the night of 24 July 2016 when Panstarrs X1 was in the constellation of Centaurus.

5 Aug 2016

The Night Sky for 15 August

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This is the night sky at 10pm for the middle of August. The Summer Triangle is prominent, it is made up from the bright stars Deneb in Cygnus, Vega in Lyra, and Altair in Aquila the eagle. The constellations of Autumn are now rising in the East, so the great Andromeda galaxy (M31) is on display for binocular observers. Scan across the Milky Way and you will many nice star clusters, and in the constellation of Hercules try to view the bright globular cluster (M13). Click on the image for more detailed information about the planets & constellations now on view in The Sky at Night.

4 Aug 2016

A postcard from Dawn: Liber crater

PIA20863Another postcard from NASA’s Dawn spacecraft.

This view features Liber Crater (14 miles, 23 kilometres wide) in Ceres' northern hemisphere, at right.

Dawn took this image on June 17, 2016, from its low-altitude mapping orbit, at a distance of about 240 miles (385 kilometres) above the surface. The image resolution is 120 feet (35 meters) per pixel.

Image Credit: NASA/JPL Caltech/UCLA/MPS/DLR/IDA

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In the next program of Astronomy & Space we will be looking at the Asteroids of the solar system. Including NASA's new asteroid-sampling mission OSIRIS-REx. It will be available to watch from 29 August.

Scientists discover Ceres to be an icy ‘slush ball’ in space

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The minor planet Ceres is the largest of the Minor planets, situated in the large gap between the planets Mars & Jupiter. It is 427 miles in diameter and takes just over 4 1/2 years to orbit around the Sun.

NASA’s Dawn spacecraft has been in orbit around Ceres for the last year taking hundreds of photographs, and making careful science observations.

Since gravity dominates Dawn's orbit at Ceres, scientists can measure variations in Ceres’ gravity by tracking subtle changes in the motion of the spacecraft. Using data from Dawn, scientists have mapped the variations in Ceres' gravity for the first time in a new study in the journal Nature, which provides clues to the dwarf planet's internal structure.

"The new data suggest that Ceres has a weak interior, and that water and other light materials partially separated from rock during a heating phase early in its history," said Ryan Park, the study’s lead author and the supervisor of the solar system dynamics group at NASA’s Jet Propulsion Laboratory, Pasadena, California.

Ceres' gravity field is measured by monitoring radio signals sent to Dawn, and then received back on Earth, by NASA’s Deep Space Network. This network is a collection of large antennas at three locations around the globe that communicate with interplanetary spacecraft. Using these signals, scientists can measure the spacecraft's speed to a precision of 0.004 inches (0.1 millimetres) per second, and then calculate the details of the gravity field.

Ceres has a special property called "hydrostatic equilibrium," which was confirmed in this study. This means that Ceres' interior is weak enough that its shape is governed by how it rotates. Scientists reached this conclusion by comparing Ceres' gravity field to its shape. Ceres' hydrostatic equilibrium is one reason why astronomers classified the body as a dwarf planet in 2006.

The data indicate that Ceres is “differentiated,” which means that it has compositionally distinct layers at different depths, with the densest layer at the core. Scientists also have found that, as they suspected, Ceres is much less dense than Earth, the moon, giant asteroid Vesta (Dawn’s previous target) and other rocky bodies in our solar system. Additionally, Ceres has long been suspected to contain low-density materials such as water ice, which the study shows separated from the rocky material and rose to the outer layer along with other light materials.

pia20358_main"We have found that the divisions between different layers are less pronounced inside Ceres than the moon and other planets in our solar system," Park said. “Earth, with its metallic core, semi-fluid mantle and outer crust, has a more clearly defined structure than Ceres," Park said.

Scientists also found that high-elevation areas on Ceres displace mass in the interior. This is analogous to how a boat floats on water: the amount of displaced water depends on the mass of the boat. Similarly, scientists conclude that Ceres’ weak mantle can be pushed aside by the mass of mountains and other high topography in the outermost layer as though the high-elevation areas "float" on the material below. This phenomenon has been observed on other planets, including Earth, but this study is the first to confirm it at Ceres.

The internal density structure, based on the new gravity data, teaches scientists about what internal processes could have occurred during the early history of Ceres. By combining this new information with previous data from Dawn about Ceres' surface composition, they can reconstruct that history: Water must have been mobile in the ancient subsurface, but the interior did not heat up to the temperatures at which silicates melt and a metallic core forms.

"We know from previous Dawn studies that there must have been interactions between water and rock inside Ceres," said Carol Raymond, a co-author and Dawn’s deputy principal investigator based at JPL. "That, combined with the new density structure, tells us that Ceres experienced a complex thermal history."

3 Aug 2016

The Fluctuating Atmosphere of Jupiter’s Volcanic Moon

nh-io-seriesJupiter’s volcanic moon Io has a thin atmosphere that collapses in the shadow of Jupiter, condensing as ice, according to a new study by NASA-funded researchers. The study reveals the freezing effects of Jupiter’s shadow during daily eclipses on the moon’s volcanic gases.

“This research is the first time scientists have observed this remarkable phenomenon directly, improving our understanding of this geologically active moon,” said Constantine Tsang, a scientist at the Southwest Research Institute in Boulder, Colorado. The study was published Aug. 2 in the Journal of Geophysical Research.

Io is the most volcanically active object in the solar system. The volcanoes are caused by tidal heating, the result of gravitational forces from Jupiter and other moons. These forces result in geological activity, most notably volcanoes that emit umbrella-like plumes of sulphur dioxide gas that can extend up to 300 miles (480 kilometres) above Io and produce extensive basaltic lava fields that can flow for hundreds of miles.

io_sulfur_dioxide_geyser_1280The new study documents atmospheric changes on Io as the giant planet casts its shadow over the moon’s surface during daily eclipses. Io’s thin atmosphere, which consists primarily of sulphur dioxide (SO2) gas emitted from volcanoes, collapses as the SO2 freezes onto the surface as ice when Io is shaded by Jupiter, then is restored when the ice warms and sublimes (I.e. transforms from solid back to gas) when the moon moves out of eclipse back into sunlight.

The study used the large eight-meter Gemini North telescope in Hawaii and an instrument called the Texas Echelon Cross Echelle Spectrograph (TEXES). Data showed that Io’s atmosphere begins to “deflate” when the temperatures drop from -235 degrees Fahrenheit in sunlight to -270 degrees Fahrenheit during eclipse. Eclipse occurs two hours of every Io day (1.7 Earth days). In full eclipse, the atmosphere effectively collapses, as most of the sulphur dioxide gas settles as frost on the moon’s surface. The atmosphere redevelops as the surface warms once the moon returns to full sunlight.

“This confirms that Io’s atmosphere is in a constant state of collapse and repair, and shows that a large fraction of the atmosphere is supported by sublimation of SO2 ice,” said John Spencer, a co-author of the new study, also at the Southwest Research Institute. “Though Io’s hyperactive volcanoes are the ultimate source of the SO2, sunlight controls the atmospheric pressure on a daily basis by controlling the temperature of the ice on the surface.  We’ve long suspected this, but can finally watch it happen.”

Io_diagram_svgPrior to the study, no direct observations of Io’s atmosphere in eclipse had been possible because Io’s atmosphere is difficult to observe in the darkness of Jupiter’s shadow.  This breakthrough was possible because TEXES measures the atmosphere using heat radiation, not sunlight, and the giant Gemini telescope can sense the faint heat signature of Io’s collapsing atmosphere.

The observations occurred over two nights in November 2013, when Io was more than 420 million miles (675 million kilometres) from Earth. On both occasions, Io was observed moving into Jupiter’s shadow for a period about 40 minutes before and after the start of the eclipse.

The research was funded by NASA’s Solar System Workings and Solar System Observations programs.