Thursday, May 31, 2012

Dragon is Home From First ISS Visit

The Space Explorations Technologies (SpaceX) Dragon spacecraft has safely splashed down about 560 miles to the west of Baja, California. Splashdown time was 11:42 AM EDT / 8:42 AM PDT. The reported coordinates were Latitude 27 degrees North, Longitude 120 degrees West, inside the planned landing area. A NASA aircraft was overhead to provide infrared imagery of Dragon's return, and recovery vessels were nearby, ready to collect the spacecraft after spashdown.

It is expecte that in approximately two days the recovery vessels will make port in Long Beach, California, where more time-sensitive items will be removed from Dragon and turned over to NASA. Following that, the spacecraft will proceed to SpaceX facilities in McGregor, Texas where SpaceX and NASA teams will "safe" the spacecraft (bleeding off the maneuvering thruster propellants, etc.) and then complete the unloading of the equipment and materials from the International Space Station (ISS).

This is the first of 12 ISS cargo missions that SpaceX has contracted for NASA through 2015, a contract totaling $1.6 billion. SpaceX has hope of expanding their ISS support role to include the transport of crew members. For more on SpaceX, visit their home page: http://www.spacex.com/

To learn more about the International Space Station, visit the following URL: www.nasa.gov/station

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Dragon on Way Home from ISS

This morning, at 4:07 AM EDT / 1:07 AM PDT, the crew of the International Space Station (ISS) released the motorized bolts that held it to the Space Exploration Technologies (SpaceX) Dragon spacecraft. All the while the spacecraft was securely held by the station's Canadian-built robotic are. The arm move the Dragon spacecraft to a safe distance from the ISS. Then, at 5:49 AM EDT / 2:49 AM PDT, the ISS crew released the arm's hold and the SpaceX ground crew assumed full control. SpaceX is currently managing the process of re-entry and and splashdown off the Baja, California peninsula. Splashdown is estimated to occur at 11:44 AM EDT / 8:44 PDT.



This is the first of 12 cargo mission that SpaceX has contracted for NASA through 2015, totaling $1.6 billion. SpaceX has hope of expanding their ISS support role to include the transport of crew members. For more on SpaceX, visit their home page: http://www.spacex.com/


To learn more about the International Space Station, visit the following URL: www.nasa.gov/station


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The Smokin' Cigar


Here is an update on the things astronomers are learning from the Spitzer Infrared Nearby Galaxy Survey, which is currently underway. The above image is a composite if the the "Cigar galaxy," Messier 82. On the left is a visible-light image from the National Optical Astronomy Observatory. On the right is a "smokin'" infrared image from NASA's Spitzer Space Telescope.

The visible-light picture of Messier 82, shows only a bar of light against a dark patch of space. Longer exposures of the galaxy have revealed cone-shaped clouds of hot gas above and below the galaxy's plane. It took Spitzer's three sensitive instruments to show that the galaxy is also surrounded by a huge, hidden halo of smoky dust (red in infrared image).

Of those instruments, Spitzer's infrared spectrograph told astronomers that the dust contains a carbon-containing compound, called polycyclic aromatic hydrocarbon. This smoky molecule can be found on Earth in tailpipes, barbecue pits and other places where combustion reactions have occurred.

Messier 82 is located about 12 million light-years away in the Ursa Major constellation. It is viewed from its side, or edge on, so it appears as a thin cigar-shaped bar. The galaxy is termed a starburst because its shrouded core is a fiery hotbed of stellar birth. A larger nearby galaxy, called Messier 81, is gravitationally interacting with Messier 82, prodding it into producing the new stars.

The infrared image was taken by Spitzer's infrared array camera as a part of the Spitzer Infrared Nearby Galaxy Survey. Blue indicates infrared light of 3.6 microns, green corresponds to 4.5 microns, and red to 5.8 and 8.0 microns. The contribution from starlight (measured at 3.6 microns) has been subtracted from the 5.8- and 8-micron images to enhance the visibility of the dust features.

You can read more and see more images at the article URL: www.jpl.nasa.gov/spaceimages/details.php?id=PIA02917

The visible-light picture is from the National Optical Astronomy Observatory, Tucson, Arizona. To learn more, visit the observatory home page: noao.edu

The Spitzer Space Telescope (SST) operations are extended through Fiscal year 2014 with closeout planned for Fiscal year 2015. Launched August 2003 aboard a Delta II rocket, Spitzer Space Telescope is an infrared space observatory, the fourth and final of the NASA Great Observatories program. The observatory was renamed in honor of Lyman Spitzer, one of the 20th century's great scientists. The mission website is: http://www.spitzer.caltech.edu/

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Wednesday, May 30, 2012

GRAIL Completes Mission in Record Time

The above image is an artist's depiction of the twin GRAIL spacecraft in the science collection phase of its mission. Image Credit: NASA/JPL-Caltech/MIT


Since March 8th, NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission has studied the moon from crust to core using its twin lunar probes, Ebb and Flow, flying in polar orbits and collecting three complete sets of data. On Tuesday, May 29th, NASA announced that GRAIL had completed its prime mission ahead of schedule. The GRAIL team is now preparing for extended science operations which will begin August 30th and continue through December 3rd.

The GRAIL mission has gathered unprecedented detail about the internal structure and evolution of the moon. This information will increase our knowledge of how Earth and its rocky neighbors in the inner solar system developed into the diverse worlds we see today.


An instrument called the Lunar Gravity Ranging System onboard each spacecraft transmits radio signals that allow scientists to translate the data into a high-resolution map of the moon's gravitational field. The spacecraft returned their last data set of the prime mission today. The instruments were turned off on Tuesday at 1 PM EDT / 10 AM PDT, when the two spacecraft were 37 miles (60 kilometers) above the Sea of Nectar.


Both spacecraft instruments will be powered back on August 30th. The spacecraft will have to endure a lunar eclipse on June 4, as well as the associated sudden changes in temperature and the energy-sapping darkness that accompanies the phenomena were expected and do not concern engineers about the spacecraft's health.

The extended mission goal is to take an even closer look at the moon's gravity field. To achieve this, GRAIL mission planners will halve their current operating altitude to the lowest altitude that can be safely maintained, averaging 14 miles (23 kilometers) during the extended mission. And the probes will be clearing some of the moon's higher surface features by about 5 miles (8 kilometers).

And now, the mission particulars...

The GRAIL mission is managed by JPL for NASA's Science Mission Directorate in Washington. The mission is part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. NASA's Deep Space Network is an international network of antennas that supports interplanetary spacecraft missions and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected Earth-orbiting missions. Lockheed Martin Space Systems in Denver built the spacecraft. JPL is a division of the California Institute of Technology in Pasadena.


For more information about GRAIL, visit: www.nasa.gov/grail .


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Tuesday, May 29, 2012

Transit Trivia: Tahiti, 1769


The above image is a drawing of Fort Venus, constructed on the island of Tahiti for the 1769 transit of Venus. The drawing was made in 1771 by Charles Praval from a picture by H.D. Söring. Image Credit: The Image is in the Public Domain.

When the Royal Society chose observing locations for viewing the 1769 transit of Venus, it followed the suggestions of the late Edmund Halley in his 1716 article. The Society chose the North Cape at the Arctic tip of Norway, Fort Churchill at Hudson Bay Canada and a yet-to-be-named island in the South Pacific.

In June 1767, British navigator Samuel Wallis (1728 – 1795) discovered the island of Tahiti. Wallis returned from his voyage in time to help the Royal Society decide that Tahiti would be an ideal location. Tahiti had a big advantage in that it was one of the few islands in the South Pacific for which they knew the longitude and latitude. But the British Admiralty was less concerned with the choice of the South Pacific island and more concerned with the secret mission that would follow the transit -- the search for the mysterious Terra Australis Incognita (the unknown land of the South).

The HMS Bark Endeavour was chosen to carry the Tahiti expedition. James Cook was commissioned as Lieutenant and appointed to command the vessel. Cook was chosen for his outstanding seamanship, his navigational qualifications, his astronomical skills, and the fact that he had previously observed the 1761 transit of Venus in Canada for the Royal Society. Also in the expedition were British astronomer Charles Green (1735 – 1771), Swedish naturalist Daniel Solander (1733 – 1782), Lieutenant and second-in-command Zachary Hickes (c. 1729 – 1771), and British American Captain John Gore (died 1790).

Two days after the Endeavour reached Tahiti, Cook began construction of an observatory on shore. The observatory would be known as "Fort Venus." In addition to the Fort Venus observations, Cook had Hickes lead a party to a point on the east coast of the island, and had Gore lead another group of thirty-eight on the neighboring island of Eimeo (now Mo'orea). In addition to these, Cook, Green and Solander would take independent observations with their own telescopes. Cook was taking every step he could think of to ensure that accurate observations were recorded for the transit.

On the day of the transit, the sky was clear and all of the locations were able to observe and record the four transit contact points. But when their results were compared, the times differed greatly, particularly for the times of second and third contact. The disagreement of the times for second and third contact is now understood to be the result of the optical phenomenon known as the black-drop effect. Cook suggested that the time differences were evidence that Venus had an atmosphere.

Following the transit, Cook and the Endeavour expedition proceeded on its secret mission to discover the southern continent. In 1770, Cook officially discovered and charted for the British government the Eastern coastline of Terra Australis (land of the South), which is known today as Australia. Cook named the charted coastline New South Wales.

During the charting of coastline, the Endeavour was damaged in a collision with the Great Barrier Reef. On the return voyage to England, the Endeavour stopped for ten weeks of repairs at the Dutch port of Batavia (now Jakarta). At that time the port was rife with fever and dysentery. Green took ill and died there. Hickes also died at Batavia, but in his case it was from consumption, an archaic name for pulmonary tuberculosis. Cook later reported that Hickes had been so afflicted since leaving England, but that it had not interfered with his duties.

Upon review of Cook's report, the Royal Society decided that the transit timing discrepancies were a failure in the observations. The Society also decided to blame Green, who was dead and so could not defend himself. Cook was also rebuked, and in a manner so sharp that the Society had it removed from its official proceedings. The Royal Society eventually learned that other observing locations had similar problems in timing because of the black-drop effect.

The next transit of Venus will occur over June 5-6. To learn more, visit these links.

2012 Transit of Venus, NASA/Goddard Space Flight Center: eclipse.gsfc.nasa.gov/OH/transit12.html

Transit of Venus, Sun-Earth Day 2012, NASA: sunearthday.nasa.gov/transitofvenus/

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Asteroid 2012 KT42 Flyby Today

Newly-discovered asteroid 2012 KT42 is flying past Earth today (May 29th) only about 14,000 km above the planet's surface. This means 2012 KT42 will actually fly inside the Clark Belt of geosynchronous satellites. 2012 KT42 is 3- to 10-meter wide and ranks # 6 on the top 20 list of closest-approachers to Earth. According to the asteroid's orbit, there is no danger of a collision. Even if it did eventually hit Earth, it is too small to cause significant damage. It would likely disintegrate almost entirely in the atmosphere, peppering the ground below with relatively small meteorites.

The asteroid was discovered by A. R. Gibbs in the course of Mt. Lemmon Survey with a 1.5-m reflector + CCD on May 28, 2012 at magnitude ~18.1.

To learn more about 2012 KT42 and the survey which led to its discovery, follow this URL:
remanzacco.blogspot.it/2012/05/2012-kt42-close-approach.html?m=1

To learn more about NASA' Near-Earth Object Program, follow this URL: neo.jpl.nasa.gov

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A New Twist on "Guess Your Weight"

This computer generated image of asteroid 1999 RQ36 was derived from data acquired by the NASA-supported Arecibo Observatory in Puerto Rico. Image Credit: NASA/NSF/Cornell/Nolan


I think this man use to work the "guess your weight" booth on the midway at the fair. Steve Chesley, a scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, has accurately determined the mass of a nearby asteroid from millions of miles away. Chesley works at JPL's Near-Earth Object Program Office and accomplished this feat by utilizing data from three NASA assets — the Goldstone Solar System Radar in the California desert, the orbiting Spitzer Space telescope, and the NASA-sponsored Arecibo Observatory in Puerto Rico.


Chesley presented his findings on Saturday, May 19, at the Asteroids, Comets and Meteors 2012 meeting in Niigata, Japan.


For Chesley to define the asteroid's mass, he first needed to understand its orbit and everything that could affect that orbit  including neighboring celestial bodies and any propulsive force (however minute) the asteroid could generate.


Incorporating extraordinarily precise observations collected by astronomer Michael Nolan at Arecibo Observatory in September 2011, Arecibo and Goldstone radar observations made in 1999 and 2005, and the gravitational effects of the sun, moon, planets and other asteroids, Chesley was able to calculate how far the asteroid deviated from its anticipated orbit. He found that 1999 RQ36 had deviated from the mathematical model by about 100 miles (160 kilometers)in the past 12 years.  The only logical explanation for this orbital change was that the space rock itself was generating a minute propulsive force known in space rock circles as the Yarkovsky effect.


The Yarkovsky effect is named for the 19th-century Russian engineer who first proposed the idea that a small, rocky space object would, over long periods of time, be noticeably nudged in its orbit by the slight push created when it absorbs sunlight and then re-emits that energy as heat. The effect is hard to measure because it's so infinitesimally small.


Chesley reported that at its peak, when the asteroid is nearest the sun, the Yarkovsky force on 1999 RQ36 is only about a half ounce — around the weight of three grapes. This is why it takes a lot of high-precision measurements over a long time to see any orbital changes. Fortunately, the Arecibo Observatory provided a dozen years of great radar data which allowed Chesley see it.


The final piece to the puzzle was provided by Josh Emery of the University of Tennessee, Knoxville, who used NASA's Spitzer Space Telescope in 2007 to study the space rock's thermal characteristics. Emery's measurements of the infrared emissions from 1999 RQ36 allowed him to derive the object's temperatures. From there he was able to determine the degree to which the asteroid is covered by an insulating blanket of fine material, which is a key factor for the Yarkovsky effect.


With the asteroid's orbit, size, thermal properties and propulsive force (Yarkovsky effect) understood, Chesley was able to perform the space rock scientist equivalent of solving for "X" and calculate its bulk density.


The results indicate that 1999 RQ36 weighs about 60 million metric tons and it is about a half kilometer across. This suggests the asteroid has about the same density as water, and likely a very porous jumble of rocks and dust.


Asteroid 1999 RQ36 is of particular interest to NASA as it is the target of the agency's OSIRIS-REx  (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) mission. Scheduled for launch in 2016, ORIRIS-Rex will visit 1999 RQ36, collect samples from the asteroid and return them to Earth.


NASA detects, tracks and characterizes asteroids and comets passing relatively close to Earth using both ground- and space-based telescopes. The Near-Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them, and establishes their orbits to determine if any could be potentially hazardous to our planet. JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.


You can get more information about asteroids and near-Earth objects is at:
www.jpl.nasa.gov/asteroidwatch .


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Monday, May 28, 2012

Transit Trivia: Guillaume Le Gentil


The above image is a portrait of Guillaume Le Gentil (1725 - 1792). The date of the original painting and the artist is unknown. Image Credit: The image is in the Public Domain.

For the 1761 transit of Venus, French astronomer Guillaume Le Gentil (1725 – 1792) tried sailing to Pondicherry in India. But when Le Gentil learned of the British occupation there, he turned back for Île de France (now Mauritius) in the Indian Ocean off the southeast coast of Africa. He was aboard a rolling ship when the day came, and so was not able to make proper observations of the transit.

After having come this far, Le Gentil thought he might as well stay and wait eight years for the 1769 transit of Venus. While waiting, Le Gentil spent some of his time mapping the eastern coast of Madagascar, the large island nation located between Île de France and the southeastern coast of Africa.

Le Gentil decided to observe the 1769 transit of Venus from Manila in the Philippines, but he encountered hostility from the Spanish authorities there. Le Gentil then decided to head back to Pondicherry, which had been his original choice for the 1761 transit, and which had been restored to France by a peace treaty in 1763.

Le Gentil arrived in Pondicherry in March 1768. He built a small observatory and patiently waited. During the month which led up to the transit, the weather was beautiful. Le Gentil had every reason to anticipate a great success.

But on the day of the transit, June 4, 1769, the skies became overcast an Le Gentil saw nothing. Years of waiting far from his home, two transits of Venus passed, and Le Gentil did not even have one recorded observation to take back to France. His disappointment drove him to the brink of insanity.

At last Le Gentil recovered enough sense and strength to return to France. But the return trip was delayed by dysentery. Later, his ship was caught in a storm and Le Gentil was dropped off at Île Bourbon (Réunion) just southwest of Île de France. There he had to wait until a Spanish ship would take him home.

Le Gentil finally arrived in Paris October 1771, eleven years after he had departed for the 1761 transit. But he soon learned that during his long absence he had been declared legally dead. As a result, someone else was given his seat in the Royal Academy of Sciences, his wife remarried, and all of Le Gentil's relatives eagerly divided his estate.

Le Gentil pursued lengthy litigation and the intervention of King Louis XV was ultimately required before normalcy was reached. In the end, Le Gentil got back his seat in the academy, he remarried, and apparently lived happily for another 21 years until his death.

The next transit of Venus will occur over June 5-6. To learn more, visit these links.

2012 Transit of Venus, NASA/Goddard Space Flight Center: eclipse.gsfc.nasa.gov/OH/transit12.html

Transit of Venus, Sun-Earth Day 2012, NASA: sunearthday.nasa.gov/transitofvenus/

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NuSTAR News Conference May 30

The above image gives a overview of the Pegasus XL NuSTAR mission profile. Image Credit: NASA

As we recently reported, NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) mission is on schedule for a June 13th launch.  On that date, no earlier than 11:30 AM EDT / 8:30 AM PDT, NuSTAR will launch from Kwajalein Atoll in the Marshall Islands. The spacecraft will lift off on an Orbital Sciences Pegasus XL launch vehicle, released from an aircraft flying south of Kwajalein.

In a couple of days, we will learn a lot more about the mission. NASA will hold a news conference on Wednesday, May 30 at 1 PM EDT / 10 AM PDT to discuss NuSTAR. The event will be at NASA Headquarters in Washington and will be broadcast live on NASA Television and streamed on NASA's website. In addition, the event will be carried live on Ustream, with a moderated chat available, at www.ustream.tv/nasajpl2 . You can ask question via Twitter using the hashtag #asknasa.

NuSTAR will observe some of the hottest, densest and most energetic objects in the universe, including black holes, their high-speed particle jets, ultra-dense neutron stars, supernova remnants and our sun. It will observe high-energy X-rays with much greater sensitivity and clarity than any mission flown to date. Among its several goals, NuSTAR will address the puzzle of how black holes and galaxies evolve together over time.

The news conference participants are:

— Paul Hertz, Astrophysics Division director at NASA Headquarters in Washington

— Fiona Harrison, NuSTAR principal investigator at the California Institute of Technology in Pasadena, California

— Daniel Stern, NuSTAR project scientist at NASA's Jet Propulsion Laboratory in Pasadena

— Yunjin Kim, NuSTAR project manager at JPL

For NASA TV streaming video, downlink and scheduling information, visit: www.nasa.gov/ntv .

And now, the mission particulars...

NuSTAR is a Small Explorer mission led Caltech and managed by JPL for NASA's Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation, Dulles, Virginia. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley; Columbia University, New York; NASA's Goddard Space Flight Center, Greenbelt, Maryland; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Livermore, California; and ATK Aerospace Systems, Goleta, California. NuSTAR will be operated by UC Berkeley, with the Italian Space Agency providing its equatorial ground station located at Malindi, Kenya. The mission's outreach program is based at Sonoma State University, Rohnert Park, Calif. NASA's Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.

For more information, visit www.nasa.gov/nustar and www.nustar.caltech.edu/ .

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Sunday, May 27, 2012

Transit Trivia: David Rittenhouse

The above image is a portrait of the American astronomer, inventor, mathematician, surveyor, scientific instrument craftsman, and public official, David Rittenhouse (1732 - 1796). The portrait includes a telescope of his own construction. The portrait was painted in 1796 by Charles Willson Peale (1741–1827) and is part of the Smithonian National Portrait Gallery. Image Credit: The image is in the Public Domain.


When Pennsylvanian David Rittenhouse was very young, his uncle died and left David his carpentry tools and instructional books. David used these to begin a career as an inventor. He also enjoyed building scale models. Rittenhouse was self-taught and showed great ability in science and mathematics. By the age of 13, Rittenhouse had mastered Isaac Newton's laws of motion and gravity.


When he was 19, Rittenhouse started a scientific instrument shop at his father's farm. His skill with instruments, particularly clocks, led Rittenhouse to construct two orreries (scale models of the solar system) for Rutgers University in New Jersey. In return for the gift, the college gave him a scholarship to attend the college, enabling him to obtain a degree in philosophy.


At the age of 28, Rittenhouse published his first mathematical paper. This would be one of many he published throughout his life.


Rittenhouse was one of the first to build a telescope in the United States. He used natural spider silk to form the reticle for the instrument, he used im his own observatory on his family farm.


In 1768, Rittenhouse was elected to membership in the American Philosophical Society, where he served as librarian, secretary and, following the death of Benjamin Franklin in 1790, vice president.


In the year that he joined, Rittenhouse announced to the Society his plans to observe the pending transit of Venus from several locations. In favor of the plan, the Society persuaded the legislature to grant 100 toward the purchase of new telescopes, and Society members volunteered to staff half of the 22 telescope stations. Rittenhouse worked tirelessly for a year in preparation for the event, even to the point of becoming ill a week before the appointed day.


Rittenhouse rallied before June 3rd and was able to begin his observations on time, but he fainted during the transit. Lying on his back beneath his telescope, trained at the afternoon sun, Rittenhouse regained consciousness after a few minutes and continued his observations. Rittenhouse's account of the transit, which was published in the American Philosophical Society's Transactions, does not mention his fainting, but it is otherwise meticulous in its documentation.


Rittenhouse used the observations to calculate a distance from Earth to the Sun of 93-million miles. (This is the approximate average distance between Earth and the Sun.) The published report of the transit was hailed by European scientists, and Rittenhouse would go on to correspond with famous contemporary astronomers, such as Jérôme Lalande and Franz Xaver von Zach.


There are many tributes to the work of David Rittenhouse. Outside of his Philadelphia farm house is an historic marker commemorating Rittenhouse's observations of, and the resulting calculations from, the 1769 transit of Venus. Elsewhere in the town, one of William Penn's original city squares — Southwest Square — was renamed Rittenhouse Square. And nearby, on Walnut Street, the University of Pennsylvania houses its Physics and Mathematics departments in the David Rittenhouse Laboratory.


The next transit of Venus will occur over June 5-6. To learn more, visit these links.


2012 Transit of Venus, NASA/Goddard Space Flight Center: eclipse.gsfc.nasa.gov/OH/transit12.html


Transit of Venus, Sun-Earth Day 2012, NASA: sunearthday.nasa.gov/transitofvenus/


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False-Color Crater Pic Prior to Opportunity Roll-Out


Above, NASA's Mars Rover Opportunity catches its own late-afternoon shadow in this dramatically lit view eastward across Endeavour Crater on Mars.
Image Credit: NASA/JPL-Caltech/Cornell/Arizona State Univ.


Like a tourist waiting for just the right lighting to snap a favorite shot, NASA's Mars Exploration Rover Opportunity used a low sun angle for a memorable view of the large Martian crater Endeavour.

The resulting view catches a shadow of the rover in the foreground and the giant basin in the distance. Opportunity is perched on the western rim of the crater looking eastward. The crater spans about 14 miles (22 kilometers) in diameter. Opportunity has been studying the edge of Endeavour Crater since arriving there in August 2011.

The scene is presented in false color to emphasize differences in materials such as dark dunes on the crater floor. This gives portions of the image an aqua tint.

Opportunity took most of the component images on March 9, 2012, while the solar-powered rover was spending several weeks at that location to preserve energy during the Martian winter. Opportunity has since resumed driving and is currently investigating a patch of windblown Martian dust near its winter haven. 

And now, the mission particulars...

The rover Opportunity and its twin, Spirit, completed their three-month prime missions on Mars in April 2004. Both rovers continued for years of bonus, extended missions. Both have made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life. Spirit stopped communicating in 2010. Since landing in the Meridiani region of Mars in January 2004, Opportunity has driven 21.4 miles (34.4 kilometers).

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, in Pasadena, manages the Mars Exploration Rover Project for NASA's Science Mission Directorate, Washington.

To lean more about the planet Mars and more about NASA's Exploring Mars Program, visit this URL:
marsprogram.jpl.nasa.gov/

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Saturday, May 26, 2012

Transit Trivia: Preparing for 1769

In 1663, Scottish mathematician James Gregory proposed using the transits of Mercury and Venus to determine the solar parallax and, from that, determine the distance from Earth to the sun, a measurement known today as the Astronomical Unit. In a 1716 issue of the Philosophical Transactions of the Royal Society, Edmund Halley repeated this proposal and explained it further. In his report, Halley suggested places that a full transit should be viewed due to a "cone of visibility." The places Halley recommended included the Hudson Bay, Norway and the Molucca Islands in the Pacific.


The viewing of the 1761 transit involved the effort of 120 observers from nine nations. But British astronomer and mathematician Thomas Hornsby (1733 - 1810) later reported that the 1761 observations were on the whole unsuccessful, primarily due to poor weather conditions. Hornsby alerted the Royal Society in 1766 that preparations needed to begin for the 1769 transit. Hornsby's publication in the Philosophical Transactions of the Royal Society in 1766 focused attention on the "cone of visibility" indicating, like Halley, some of the better places to observe the transit. The Royal Society boasted that the British "were inferior to no nation on earth, ancient or modern" and were eager to make another attempt.


When choosing locations for viewing the 1769 transit, The Royal Society basically chose those Halley suggested in his 1716 article. The committee recommended that the transit be observed from three points: the North Cape at the Arctic tip of Norway, Fort Churchill at Hudson Bay, Canada and a suitable island in the South Pacific. They stated that two competent observers were to be sent to each location. King George III approved of the project and arranged for the Navy to provide ships. He allocated to the society 4,000 pounds to help fund the British expeditions.


The Czech Jesuit, astronomer and teacher Christian Mayer (1719 - 1783) was invited by Empress of Russia Catherine the Great to observe the transit in Saint Petersburg along with Swedish-born Russian astronomer, mathematician, and physicist Anders Johan Lexell (1740 - 1784). Other members of the Russian Academy of Sciences went to eight other locations in the Russian Empire.


In Philadelphia, the American Philosophical Society erected three temporary observatories and appointed a committee led by the renowned American astronomer, inventor, clockmaker, mathematician, surveyor, scientific instrument craftsman and public official, David Rittenhouse (1732 - 1796). The results of these observations would later be printed in the first volume of the Society's Transactions, published in 1771.


In addition, scientists traveled to San José del Cabo (Baja California, then under Spanish control). Regardless of the expedition and the location, all observers had high hopes for results that were better than the 1761 transit...

The next transit of Venus will occur over June 5-6. To learn more, visit these links.

2012 Transit of Venus, NASA/Goddard Space Flight Center: eclipse.gsfc.nasa.gov/OH/transit12.html

Transit of Venus, Sun-Earth Day 2012, NASA: sunearthday.nasa.gov/transitofvenus/

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Dawn Rising Over Vesta



The above images are of Aquilia crater and the surrounding surface. The left image shows the apparent brightness of the surface. The right image is a color-coded representation of the topography. Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA


Let's check in on NASA's Dawn mission to Vesta and Ceres in the asteroid belt. At the moment, Dawn and Vesta are orbiting the sun at a point that is roughly opposite the sun as seen from Earth. Only a few Earth probes have ever operated so far from home.


Beginning December 1, the Dawn spacecraft performed a low-altitude study of Vesta, orbiting at an average altitude of 210 kilometers (130 miles). At this point in the mission, the Dawn team could not be happier, and for two very good reasons. First, because the mission got 40-day extension to their stay at Vesta. And second, because that extension allow them to spend another month in their low orbit, and collect even more great data.


On May 1, the team began navigating the Dawn spacecraft through a six-week ascent to high orbit. And thanks to the earlier extension, the team will have more time up there to study Vesta before departing on August 26, 2012 (my birthday) for the long journey to Ceres.


As of May 22nd, the Dawn spacecraft was at an average altitude of about 450 kilometers (280 miles), over twice its altitude during its low-orbit phase. But the planned ascent has another three weeks to go and the ion propulsion system continues to run just fine. Dawn's destination is an altitude of about 680 kilometers (420 miles), where it will conduct a series of mapping orbits.


While Dawn is rising (pun intended), we have some time to learn a bit about how Dawn gather's it surface data. The above images of Aquilia crater and the surrounding surface can provide an example of the process. The left-hand image is a Dawn FC (framing camera) image, which shows the apparent brightness of Vesta's surface. The right-hand image is based on this apparent brightness image, which has had a color-coded height representation of the topography overlain onto it. The topography is calculated from a set of images that were observed from different viewing directions, which allows stereo reconstruction. The various colors correspond to the height of the area. The white and red areas in the topography image are the highest areas and the blue areas are the lowest areas. Aquilia crater is the large crater that dominates the top part of both images. The three-dimensional structure of Aquilia is clearer in the topography image: the deepest part of the crater (colored blue) is offset from the crater's center, the smaller crater on Aquila's rim is also relatively deep and the top side of Aquila is steeper than the opposite side.


These images are located in Vesta's Pinaria quadrangle, in Vesta's southern hemisphere. NASA's Dawn spacecraft obtained the apparent brightness image with its framing camera on Oct. 16, 2011. This image was taken through the camera's clear filter. The distance to the surface of Vesta is 700 kilometers (435 miles) and the image has a resolution of about 70 meters (230 feet) per pixel. This image was acquired during the HAMO (high-altitude mapping orbit) phase of the mission. These images are lambert-azimuthal map projected.


And now, the mission particulars...


The Dawn mission to Vesta and Ceres is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, for NASA's Science Mission Directorate, Washington D.C. UCLA is responsible for overall Dawn mission science. The Dawn framing cameras have been developed and built under the leadership of the Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, with significant contributions by DLR German Aerospace Center, Institute of Planetary Research, Berlin, and in coordination with the Institute of Computer and Communication Network Engineering, Braunschweig. The Framing Camera project is funded by the Max Planck Society, DLR, and NASA/JPL.


For more information about the Dawn mission, visit: www.nasa.gov/dawn and dawn.jpl.nasa.gov .

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Friday, May 25, 2012

ISS Captures a Dragon

The above image shows the the SpaceX Dragon spacecraft immediatly following capture by the ISS robotic arm. Image Credit: NASA

A few minutes ago, at 8:56 AM CT / 9:56 AM ET, the crew of the International Space Station (ISS) used their robotic arm to successfully capture the Space Exploration Technologies (SpaceX) Dragon spacecraft as it held position meters from the ISS. At the time of capture, the ISS and Dragon were on the night side of Earth, passing over northwestern Australia.

Once the ISS crew completes their visual inspection of the spacecraft, they and the ground crews will begin the process of caring the Dragon spacecraft to the designated ISS docking port for the "birthing" of the spacecraft. Some time later, the ISS crew will step through a two-hour process to open the Dragon hatch and then begin unloading the ISS supplies. While these steps may seem a bit tedious, they are necessary precautions because of the new spacecraft, new SpaceX ground support crew and new procedures.

This is the first of 12 cargo mission that SpaceX has contracted for NASA through 2015, totaling $1.6 billion. SpaceX has hope of expanding their ISS support role to include the transport of crew members. For more on SpaceX, visit their home page: http://www.spacex.com/

To learn more about the International Space Station, visit the following URL: www.nasa.gov/station

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NuSTAR on Schedule for June Launch

The above image is an artist's concept showing the NuSTAR X-ray telescope in orbit. NuSTAR uses two identical optics modules (shown at right) in order to increase sensitivity. The background shows an image of the galactic center as taken from the Chandra X-ray Observatory. Image Credit: NASA

Here is an update on pre-launch preparations for NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR. To remind you, NuSTAR is a space-based X-ray telescope that will focus high energy X-rays to (1) conduct a deep survey for black holes a billion times more massive than our sun, (2) to understand how particles are accelerated to within a fraction of a percent of the speed of light in active galaxies, and (3) to understand how the elements are created in the explosions of massive stars by imaging the remains, or supernova remnants.

The mission was scheduled for a March 21 launch, but was postponed in mid-March because of software issues with the Pegasus launch vehicle. The mission is scheduled to launch no earlier than June 13 from Kwajalein Atoll in the Marshall Islands. The NuSTAR observatory will launch from the belly of Orbital Sciences Corporation's L-1011 "Stargazer" aircraft aboard the company's Pegasus rocket.

Technicians at Vandenberg Air Force Base in central California are busy installing the rocket's fairing, or nose cone, around the observatory. A flight computer software evaluation is also nearing completion and should be finished before the Flight Readiness Review, which is scheduled for June 1. A successful launch simulation of the Orbital Sciences' Pegasus XL rocket was conducted last week.

The mission plan is for NuSTAR and the Pegasus to be attached to the Stargazer aircraft on June 2. The aircraft will depart California on June 5 and arrive at the Kwajalein launch site on June 6. The launch of NuSTAR from the Stargazer is targeted for 8:30 AM PDT (11:30 AM EDT) on June 13.

And now, the mission particulars...

NuSTAR is the eleventh mission of the NASA Small Explore satellite program (SMEX-11) and the first space-based direct-imaging X-ray telescope at energies beyond those of the Chandra X-ray Observatory and XMM-Newton. NuSTAR is led by the California Institute of Technology in Pasadena and managed by NASA's Jet Propulsion Laboratory, also in Pasadena, for NASA's Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation, Dulles, Virginia. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley; Columbia University, New York; NASA's Goddard Space Flight Center, Greenbelt,  Maryland; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Livermore, California; and ATK Aerospace Systems, Goleta, California. NuSTAR will be operated by UC Berkeley, with the Italian Space Agency providing its equatorial ground station located at Malindi, Kenya. The mission's outreach program is based at Sonoma State University, Rohnert Park, California. NASA's Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.

For more information, visit www.nasa.gov/nustar .

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Thursday, May 24, 2012

SpaceX Dragon Set for ISS Docking May 25


The above image shows the SpaceX Dragon spacecraft (below and to the right of center) about 2.4 kilometers below the International Space Station on Thursday, May 24. Image Credit: NASA

Congratulations to Space Exporation Technologies (SpaceX) on their achievements so far this week. On Tuesday, May 22, at 3:44 AM ET, SpaceX's Falcon 9 rocket launched from Cape Canaveral, sending the Dragon spacecraft on its first NASA-contracted resupply mission to the International Space Station (ISS).

On Thursday, Dragon approached to 2.4 kilometers below the ISS. The spacecraft completed two key tests at that distance: Dragon demonstrated its Relative GPS and established a communications link with the International Space Station using CUCU. The ISS crew was able to command Dragon’s strobe light to confirm the link was working.

Friday morning, around 9:00 AM ET, astronauts aboard the ISS will grapple Dragon with the stations robotic arm and attach the craft to the station. If all goes well, the ISS crew will begin a two-hour procedure to open the Dragon hatch, enter the spacecraft and being unloading the supplies.

SpaceX currently has a $1.6 billion contract with NASA for 12 cargo missions through 2015. And the company has hopes of expanding their support role to include the transport of ISS crew members. For more on SpaceX, visit their home page: http://www.spacex.com/

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Kepler Sees a Possibly-Evaporating Exoplanet


The above image is an artist's concept of the comet-like tail that may be trailing from a super Mercury-size planet candidate as it transits its parent star, KIC 12557548. Image Credit: NASA/JPL-Caltech

What a switch! Astronomers have seen comets disintegrate as they circle too closely around our star. But now, using NASA's Kepler mission, astronomers may have detected evidence of an exoplanet candidate 1,500 light-years away from Earth, disintegrating under the searing heat of its own star.

This super Mercury-size planet appears to be trailing debris similar to a comet. But if this is correct, the planet won't last for long. Scientists calculate that, at the current rate of evaporation, the dusty world could be completely vaporized within 200 million years.

Launched March 2009, the Kepler observatory mission detects planets and planet candidates by measuring dips in the brightness of more than 150,000 stars to search for planets crossing in front of — transiting — their stars. The current commotion started when astronomers identified an unusual light pattern emanating from a star named KIC 12557548, one of those in Kepler's field-of-view.

Orbiting a star smaller and cooler than our sun, the planet candidate completes its orbit in less than 16 hours — making it one of the shortest orbits ever detected. At an orbital distance of only twice the diameter of its star, the surface temperature of the planet is estimated to be a smoldering 3,300 degrees Fahrenheit (1,816 degrees Celsius).

Scientists think that the star-facing side of the potentially rocky inferno is an ocean of seething magma. The surface melts and evaporates at such high temperatures that the energy from the resulting wind is great enough to allow dust and gas to escape into space. This dusty effluence trails behind the body as it disintegrates around the star.

Additional follow-up observations are needed to confirm the candidate as a planet. More details on the finding can be found in a Massachusetts Institute of Technology news release at: web.mit.edu/newsoffice/2012/dusty-exoplanet-0517.html .

A technical paper is published in The Astrophysical Journal and is available for download at: arxiv.org/abs/1201.2662 .

And now, the mission particulars...

NASA's Ames Research Center in Moffett Field, California, manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory, Pasadena, California, managed the Kepler mission's development. Ball Aerospace and Technologies Corp. in Boulder, Colorado, developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters in Washington.

For more information about the Kepler mission, visit: www.nasa.gov/kepler .

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Wednesday, May 23, 2012

Transit Trivia: The Black-Drop Effect


The above image is a series of drawings of the black-drop effect as depicted by Swedish chemist and mineralogist Torbern Olaf Bergman (1735 - 1784). Bergman made the drawings based on his observations of the 1761 transit of Venus. Image Credit: The image is in the Public Domain.

We have seen that the 1761 transit of Venus was historic for several reasons. We now consider another: the first recording of the black-drop effect.

Before we go too far, we should review some terminology. The timing of a transit depends on the recording of four critical contact points. These points are quite logically labeled "first," "second," "third," and "fourth contact." First contact is the point when the transiting body first appears to touch (or bites into) the disc of the sun. Second contact is the point when the transiting body completely moves into the disc of the sun. Third contact is the point when the transiting body breaks the far edge of the sun's disc. And fourth contact is the point when the transiting body completely clears the sun's disc.

British astronomer Edmund Halley had encouraged international cooperation in observing the 1761 transit of Venus and had stressed the importance of accurately recording — to the second, the thought — the times of these four points of contact. The data from the various expeditions could then be use to determine the solar parallax and, from that, the distance from Earth to the sun — a foundational measurement in astronomy that has come to be known as the Astronomical Unit.

But the observing teams ran into difficulties in recording the times for second contact and third contact. It seemed there was not a clear agreement on the point of completely moving onto the disc (for second contact), or the point of touching the the edge of the disc (for third contact). In fact, within the same teams, different observers recorded different times.

This optical phenomenon has come to be known as the "black-drop effect." The effect gets its name from the shape created as the transiting body moves onto and off of the sun's disc. At the points of second contact and third contact, the transiting body and the nearest edge of the sun's disc appear to elongate toward each other, thus creating a shape that resembled a drop of black fluid. Some refer to this shape as a "tear drop."

Over time, different causes have been suggested for the phenomenon. At first, it was suggested that the phenomenon was evidence that Venus had an atmosphere. Later, it was suggested that the phenomenon was caused by turbulence in Earth's atmosphere or by imperfections in the viewing aparatus.

While it was later confirmed by other methods that Venus had an atmosphere, this was eventually ruled out as the reason for the black-drop effect, because the phenomenon has also be seen during transits of Mercury, which has no significant atmosphere. As to the cause being atmospheric turbulence, this possibility was eliminated following the 1999 and 2003 observations of the transit of Mercury, which were made from Earth orbit using NASA's Transition Region and Coronal Explorer (TRACE). During both transits the black drop effect was observed.

So what is the cause of the black-drop effect? An answer is proposed by Jay M. Pasachoff, Glenn Schneider, and Leon Golub, the ones who studied the results of the 1999 and 2003 Mercury transits observed by TRACE. According to the trio, the cause of the black-drop effect is a combination of two factors: the point-spread function of the imaging system and solar limb darkening.

A point-spread function (PSF) is the method by which an imaging system responds to a point source or point object. The imaging system may be artificial, as with a CCD devices, and it may be natural, as with human eyes.

Solar limb darkening refers to the gradual diminishing of the sun's brightness as one moves from the center to the edge of the solar disc. This darkening is in turn the result of two effects. The first is that the density of the star diminishes as the distance from the center increases. The second is that the temperature of the star diminishes as the distance from the center increases.

The team found that when the these two factors were removed, the black-drop effect was not evident. The team's final report is available to read online: "Space Studies of the Black-Drop Effect at a Mercury Transit." G. Schneider, J. M. Pasachoff, L. Golub. Submitted October 14, 2003. Cornell University Library. URL: arxiv.org/abs/astro-ph/0310379v1

The next transit of Venus will occur over June 5-6. To learn more, visit these links.

2012 Transit of Venus, NASA/Goddard Space Flight Center: eclipse.gsfc.nasa.gov/OH/transit12.html

Transit of Venus, Sun-Earth Day 2012, NASA: sunearthday.nasa.gov/transitofvenus/

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Herschel and the Galactic Bridge


The above image, taken by the Herschel Space Observatory, shows a giant, galaxy-packed filament ablaze with billions of new stars. The filament connects two clusters of galaxies that, along with a third cluster, will smash together in several billion years and give rise to one of the largest galaxy superclusters in the universe. A white circle outlines the 8 million light-year-long intergalactic filament in each image. In visible light, the filament does not stand out because dust obscures the star-formation activity in distant galaxies. Image Credit: ESA/NASA/JPL-Caltech/CXC/McGill University

The Herschel Space Observatory has discovered a giant, galaxy-packed filament ablaze with billions of new stars. The filament connects two clusters of galaxies that, along with a third cluster, will eventually smash together, creating one of the largest galaxy superclusters in the universe.

To refresh, Herschel is a European Space Agency (ESA) mission with important contributions by NASA. Launched May 2009 and named after British astronomer William Herschel, the orbital observatory studies the universe in the far-infrared and submillimeter portions of the electromagnetic spectrum.

The filament observed by Herschel is the first structure of its kind seen in a critical era of cosmic buildup when colossal collections of galaxies called superclusters began to take shape. The glowing galactic bridge offers astronomers a unique opportunity to explore how galaxies evolve and merge to form superclusters.

The mission team members are excited about the filament, because they think the intense star formation they see in its galaxies is related to the consolidation of the surrounding supercluster. The details appear in a new paper published April 3rd in the Astrophysical Journal Letters by members of the Herschel mission team.

The intergalactic filament, which contains hundreds of galaxies, spans 8 million light-years and links two of the three clusters that make up a supercluster known as RCS2319. This emerging supercluster is an extremely rare, distant object whose light has taken more than seven billion years to reach Earth.

RCS2319 is the subject of a huge observational study. Previous observations in visible and X-ray light had found the cluster cores and hinted at the presence of a filament. It was not until astronomers trained Herschel on the region, however, that the intense star-forming activity in the filament became clear. Dust obscures much of the star-formation activity in the early universe, but telescopes like Herschel can detect the infrared glow of this dust as it is heated by nascent stars.

The amount of infrared light suggests that the galaxies in the filament are cranking out the equivalent of about 1,000 solar masses (the mass of our sun) of new stars per year. For comparison's sake, our Milky Way galaxy is producing about one solar-mass worth of new stars per year. Researchers chalk up the blistering pace of star formation in the filament to the fact that galaxies within it are being crunched into a relatively small cosmic volume under the force of gravity. By studying the filament, astronomers will be able to explore the fundamental issue of whether "nature" versus "nurture" matters more in the life progression of a galaxy.

There is lots more to read in the new paper. Please check it out. "The Herschel Filament: A Signature of the Environmental Drivers of Galaxy Evolution During the Assembly of Massive Clusters at z= 0.9*." April 3, 2012. Astrophysical Journal Letters, Volume 749, Number 2:
iopscience.iop.org/2041-8205/749/2/L43/

And now, the mission particulars...

Herschel is a European Space Agency cornerstone mission, with science instruments provided by consortia of European institutes and with important participation by NASA. NASA's Herschel Project Office is based at NASA's Jet Propulsion Laboratory, Pasadena, California. JPL contributed mission-enabling technology for two of Herschel's three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the United States astronomical community. Caltech manages JPL for NASA. More mission information is online at http://www.herschel.caltech.edu/ , www.nasa.gov/herschel and www.esa.int/SPECIALS/Herschel .

There is lots more to read in the team's paper. Please check it out. "The Herschel Filament: A Signature of the Environmental Drivers of Galaxy Evolution During the Assembly of Massive Clusters at z= 0.9*." April 3, 2012. Astrophysical Journal Letters, Volume 749, Number 2:
iopscience.iop.org/2041-8205/749/2/L43/ 

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Tuesday, May 22, 2012

WISE and PHAs


The above image presents an edge-on view if the inner solar system with the mapped positions of know potentially-hazardous asteroids, or PHAs. The PHA data was gathered by NASA's NEOWISE survey. Image Credit: NASA/JPL-Caltech


Potentially hazardous asteroids, or PHAs, are a subset of the larger group of near-Earth asteroids (NEAs). The PHAs have the closest orbits to Earth's, coming within five million miles (about eight million kilometers), and they are big enough to survive passing through Earth's atmosphere and cause damage on a regional, or greater, scale.


But recent observations from NASA's Wide-field Infrared Survey Explorer (WISE) have led to the best assessment yet of our solar system's population of PHAs. The new results come from a project surveying Near-Earth Objects using the WISE mission, called NEOWISE. The project sampled 107 PHAs to make predictions about the entire population as a whole. Findings indicate there are roughly 4,700 PHAs, plus or minus 1,500, with diameters larger than 330 feet (about 100 meters). So far, an estimated 20 to 30 percent of these objects have been found.


Previous estimates of PHAs predicted similar numbers, but they were rough approximations. NEOWISE has generated a more credible estimate of the objects' total numbers and sizes.


The new analysis also suggests that about twice as many PHAs as previously thought are likely to reside in "lower-inclination" orbits, which are more aligned with the plane of Earth's orbit. In addition, these lower-inclination objects appear to be somewhat brighter and smaller than the other near-Earth asteroids that spend more time far away from Earth. A possible explanation is that many of the PHAs may have originated from a collision between two asteroids in the main belt lying between Mars and Jupiter. A larger body with a low-inclination orbit may have broken up in the main belt, causing some of the fragments to drift into orbits closer to Earth and eventually become PHAs.


Asteroids with lower-inclination orbits would be more likely to encounter Earth and would be easier to reach. The results therefore suggest more near-Earth objects might be available for future robotic or human missions.


The discovery that many PHAs tend to be bright says something about their composition; they are more likely to be either stony, like granite, or metallic. This type of information is important in assessing their potential hazards to Earth. The composition of the bodies would affect how quickly they might burn up in our atmosphere if an encounter were to take place. The NEOWISE results have been accepted for publication in the Astrophysical Journal.


And now, the mission particulars...


The WISE spacecraft scanned the sky twice in infrared light before entering hibernation mode in early 2011. It catalogued hundreds of millions of objects, including super-luminous galaxies, stellar nurseries and closer-to-home asteroids. The NEOWISE project captured images of about 600 near-Earth asteroids, about 135 of which were new discoveries. Because the telescope detected the infrared light, or heat, of asteroids, it was able to pick up both light and dark objects, resulting in a more representative look at the entire population. The infrared data allowed astronomers to make good measurements of the asteroids' diameters and, when combined with visible light observations, how much sunlight they reflect.


JPL manages, and operates the Wide-field Infrared Survey Explorer for NASA's Science  Mission Directorate, Washington. The principal investigator, Edward Wright, is at UCLA. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colorado. Science operations and data processing and archiving take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.


More information is online at www.nasa.gov/wise and jpl.nasa.gov/wise .


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Monday, May 21, 2012

Transit Trivia: The Challenges of 1761

During the 1761 transit of Venus, astronomers observed the event from about sixty locations around the world. In addition to Mason and Dixon observing at the Cape of Good Hope, and Lomonosov observing from St. Petersburg, Russia, the list of others reads like an astronomical Who’s Who of the day.

French astronomer Jean-Baptiste Chappe d'Auteroche (1722 – 1769) was chosen to go to Tobolsk in Central Siberia. The trip was arduous and Chappe arrived in Tobolsk with little time to spare, although he was able to observe the lunar eclipse of May 18th, which enabled him to calculate the longitude of Tobolsk. The spring floods of the Tobol and Irtysh rivers had been particularly severe that year, and some of the local peasants blamed the foreigner with his strange equipment who was "messing with the Sun": Chappe had to be protected by a cordon of armed Cossacks to make his observations. Fortunately, the weather conditions were excellent, and Chappe was able to observe the entire transit. He published his results from Saint Petersburg (Mémoire du passage de Vénus sur le soleil, avec des observations sur l'astronomie et la déclinaison de la boussole faites à Tobolsk, en Sibérie), and did not return to France until 1763.

French astronomer, priest, and naval geographer Alexandre Guy Pingré (1711 – 1796) was chosen to observe on Rodrigues Island near Madagascar, of the southeastern coast of Africa. Pingré had poor eyesight, but outstanding mathematic skills. As it turned out, the visibility of the transit from this location was less than ideal.

American mathematician, physicist and astronomer John Winthrop (1714 - 1779) observed from St. Johns, Nova Scotia. Winthrop traveled there in a ship provided by the Province of Massachusetts - probably the first scientific expedition ever sent out by any incipient American state.

French astronomer and cartographer César-François Cassini de Thury (1714 – 1784) observed at Vienna in Austria. Cassini de Thury was a grandson of Giovanni Domenico Cassini, and would become the father of Jean-Dominique, comte de Cassini.

Many observers failed to get to their primary observing sites due to military action of the ongoing Seven Years’ War. For instance, Mason and Dixon were traveling to Bencoolen in Sumatra, but settled for the Cape of Good Hope.

French astronomer Guillaume Le Gentil (1725 – 1792) tried to reach Pondicherry in India. When his expedition had nearly arrived they learned that the British had occupied Pondicherry, so the frigate was obliged to return to Île de France. On June 6, the day of the transit, came, and the sky was clear, but he could not take astronomical observations with the vessel rolling about. After having come this far, he thought he might as well wait for the next transit of Venus, which would come in 1769.

The next transit of Venus will occur over June 5-6. To learn more, visit these links.

2012 Transit of Venus, NASA/Goddard Space Flight Center: eclipse.gsfc.nasa.gov/OH/transit12.html

Transit of Venus, Sun-Earth Day 2012, NASA: sunearthday.nasa.gov/transitofvenus/

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Missing Mass = Rogue Planets?


The above image from 2011 is an artist's concept of how a Jupiter-like rogue planet might appear as it drifted through space. Image Credit: NASA/JPL-Caltech


Two studies were recently published which cast doubt on the theory that a mysterious substance known as "dark matter" is responsible for the missing material in the universe. Now, another study proposes a radical and new solution — free-floating, rogue planets.


The dark matter theory that presumably would be pushed aside by this proposal — should it prove correct — was devised to explain why about four fifths of the ma­te­ri­al in the cos­mos seems to be missing, but is apparently detectable through gravitational effects over huge distances, but is un­seen.


Through extensive calculations, many astronomers have concluded that the mis­sing ma­te­ri­al should consist of enormous clouds of some sort of particles, of­ten dubbed cold dark matter. These clouds are sup­posed to envelop and fill galaxies.


These new studies raise problems with dark matter theory. One of them found that in our section of the galaxy, dark matter simply cannot be found, whether through gravitational effects or otherwise.


The new proposal, published online May 8th in the re­search journal Astrophysics and Space Science, argues that a few hundred thou­sand billion free-float­ing, Earth-sized planets may ex­ist in our galaxy, the Milky Way, and would be among the old­est objects in our universe. What's more, some of these bodies may pass through our solar sys­tem or others from time to time, picking up a few stray bits of DNA or living cells along the way, creating new seed­ing sites for life. The new proposal is co-authored by N. Chandra Wickramasinghe and colleagues at the University of Buckingham, U.K.


This proposal supports the "panspermia" theory, popular in some circles of astronomers, hold­ing that life or seeds of it could spread through­out the cos­mos aboard asteroids or through other means. In 2008, an In­di­an scientist pro­posed that some unidentifiable red cells found in rain could have come from space, many researchers dismissed his claim, but this proposal defends it.


Support for panspermia is uneven among astronomers, but interest in searching for planets has reached a near fever pitch since 1995, when the first plan­et out­side our solar sys­tem was reported. All the 750 or so planets reported to date or­bit stars, and just a handful have been deemed potential candidates for life.


But the possibility of a much larger number of planets was first suggested in ear­li­er studies through the effects of "gravitational lensing." This effect occurs when an object's gravitational field distorts im­ages of other objects be­hind it. In this case, the objects in question are planet-sized bodies distorting the images of distant quasars, enormously bright light sources in the very distant universe.


Several groups of investigators have recently suggested that a few billion rogue planets could exist in the galaxy. The new proposal includes new calculations that increase the total to a few hundred thousand billion. It also estimates that a rogue planet might visit our inner solar system every 26 million years.


The Astrophysical Journal is a peer-reviewed scientific journal covering astronomy and astrophysics. To read more, visit the publication URL here: iopscience.iop.org/0004-637X


To learn more about exoplanets and NASA's planet-finding program, PlanetQuest, visit this URL: planetquest.jpl.nasa.gov


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Sunday, May 20, 2012

Transit Trivia: Mikhail Lomonosov


The above image is a portrait of Mikhail Lomonosov, painted in 1787 by L. S. Miropol'sky, copied from an original work by G. Prenner. Image Credit: The image is in the Public Domain.

During the 1761 transit of Venus, the Russian polymath, scientist and writer Mikhail Lomonosov (1711 – 1765) took his measurements from the Petersburg Observatory in Russia. Lomonosov had hoped to find the planet’s diameter by measuring the size of its dark outline. He was able to determine that Venus was similar in diameter to Earth, but the precision of his measurement was hampered by the fact that the edges of the planet’s disc were not sharp, but fuzzy and indistinct. And this led Lomonosov to another discovery… Venus had an atmosphere!

In addition to the disc of Venus being fuzzy, Lomonosov detected the refraction of solar rays and inferred that only refraction through an atmosphere could explain the appearance of a light ring around the part of Venus that had not yet come into contact with the sun’s disc during the initial phase of the transit. In his writings, Lomonosov concluded that Venus had “an atmosphere equal to, if not greater than, that which envelops our earthly sphere.”


The next transit of Venus will occur over June 5-6. To learn more, visit these links.

2012 Transit of Venus, NASA/Goddard Space Flight Center: eclipse.gsfc.nasa.gov/OH/transit12.html

Transit of Venus, Sun-Earth Day 2012, NASA: sunearthday.nasa.gov/transitofvenus/

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May 16 Video Touring Vesta's Craters

On May 16th, NASA's Dawn Mission team released a nifty new video of asteroid Vesta. The stitched-together surface images were taken by the Dawn spacecraft from August through November of 2011. The 2-minute and 25-second video presents views of the Rheasilvia basin at Vesta's south pole, the three-crater feature that has come to be known as the "snowman," and Oppia crater, in the southern hemisphere. The video was produced by NASA/JPL-Caltech/
UCLA/MPS/DLR/IDA. Enjoy.


dawn.jpl.nasa.gov/multimedia/video/TouringVestasCraters.mov


For more Vesta videos and more on NASA's Dawn Mission, visit the mission home page at this URL: dawn.jpl.nasa.gov


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Saturday, May 19, 2012

Transit Trivia: Mason and Dixon



The above image presents the surveyed line (in red) which separated Pennsylvania and Delaware from Maryland and West Virginia. The line is commonly known as the Mason-Dixon Line. Image Credit: The image is in the Public Domain.


Encouraged by the appeals of the late Edmund Halley, Many expeditions were made to various parts of the world so that precise observations could be made of the Venus transit of 1761. These observations could then be used to calculate a more precise solar parallax, and thus a more accurate distance between Earth and the sun — a measurement which we today describe as an Astronomical Unit.


Despite the fact that this transit took place during the latter half of the Seven Years' War (1756-1763), a worldwide conflict involving the major powers of the time and their colonies, the event was an early example of international scientific collaboration. Scientists and explorers from Britain, Austria and France traveled to destinations around the world, including Siberia, Norway, Newfoundland and Madagascar. Most of the teams managed to observe at least part of the transit, but successful observations were made in particular by English surveyor and astronomer Jeremiah Dixon (1733 – 1779) and English astronomer Charles Mason (1728 – 1786). The pair took their measurements from the Cape of Good Hope on the southern tip of Africa.

If the names Dixon and Mason sound otherwise familiar, it might be because of some other measurements they made together. From November 1763 to 1768, Mason and Dixon established the boundary line between the American provinces of Pennsylvania and Maryland. Colonial surveyors had been unable to accurately establish the boundary due to their poor training and inadequate scientific instruments. Mason and Dixon, accompanied by a large party of assistants, established three important boundaries: (1) the south boundary line of Pennsylvania separating it from Maryland and Virginia; (2) the west boundary of the three lower counties of Pennsylvania (now Delaware) separating it from Maryland; and (3) the south boundary of the three lower counties. The two men also conducted a number of experiments for the Royal Society such as measuring a degree of longitude.

The second boundary referenced, which would separate Pennsylvania and Maryland, became commonly known as Mason and Dixon’s Line, or the Mason-Dixon Line. When projected westward, the line came to symbolize a cultural boundary between the Northeastern United States and the Southern United States — which was later given the nickname “Dixie.”


The next transit of Venus will occur over June 5-6. To learn more, visit these links.


2012 Transit of Venus, NASA/Goddard Space Flight Center: eclipse.gsfc.nasa.gov/OH/transit12.html


Transit of Venus, Sun-Earth Day 2012, NASA: sunearthday.nasa.gov/transitofvenus/


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Safe Viewing With a Pinhole Camera

The above image demonstrates the use of a pinhole camera to safely view the sun. Such a device could be very handy for the May 20 annular eclipse and the transit of Venus over June 5-6. Image Credit: NASA/JPL-Caltech

As you may well know by now, Earth will be treated to an annular solar eclipse this Sunday, May 20th, and a transit of Venus over June 5-6. Because solar safety bears repeating, we will do so now.

ATTENTION! You should never, never look at the sun directly, even with binoculars or a telescope, because you could severely damage your eyes or even go blind! Now that we have that out of the way...

There are special filtering materials that, when used correctly, allow you to view the sun safely. If you do not have these, or you are not certain how to use them, do not take chances. Instead, view the sun using a projection method.

If you have binoculars or a telescope, you may use them to project an image. We discussed this method in a May 18th posting, so just read back.

If you do not have a telescope or binoculars, no worries! You can still enjoy the event using a pinhole camera that you can make yourself, cheaply and easily.

JPL Education has created a wonderful page, compete with pictures, that walks you through the entire project. Please check it out and tell a friend!

"How to Make a Pinhole Camera." JPL Education, NASA/JPL-Caltech: www.jpl.nasa.gov/education/index.cfm?page=341

For more information on eclipses, visit this site: eclipse.gsfc.nasa.gov/eclipse.html

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