NASA Finds Super-Hot Planet with Unique Comet-Like Tail

Astronomers using NASA's Hubble Space Telescope have confirmed the existence of a baked object that could be called a "cometary planet." The gas giant planet, named HD 209458b, is orbiting so close to its star that its heated atmosphere is escaping into space.

Observations taken with Hubble's Cosmic Origins Spectrograph (COS) suggest powerful stellar winds are sweeping the cast-off atmospheric material behind the scorched planet and shaping it into a comet-like tail.

"Since 2003 scientists have theorized the lost mass is being pushed back into a tail, and they have even calculated what it looks like," said astronomer Jeffrey Linsky of the University of Colorado in Boulder, leader of the COS study. "We think we have the best observational evidence to support that theory. We have measured gas coming off the planet at specific speeds, some coming toward Earth. The most likely interpretation is that we have measured the velocity of material in a tail."

The planet, located 153 light-years from Earth, weighs slightly less than Jupiter but orbits 100 times closer to its star than the Jovian giant. The roasted planet zips around its star in a short 3.5 days. In contrast, our solar system's fastest planet, Mercury, orbits the Sun in 88 days. The extrasolar planet is one of the most intensely scrutinized, because it is the first of the few known alien worlds that can be seen passing in front of, or transiting, its star. Linsky and his team used COS to analyze the planet's atmosphere during transiting events. During a transit, astronomers study the structure and chemical makeup of a planet's atmosphere by sampling the starlight that passes through it. The dip in starlight because of the planet's passage, excluding the atmosphere, is very small, only about 1.5 percent. When the atmosphere is added, the dip jumps to 8 percent, indicating a bloated atmosphere.

Illustration Credit: NASA, ESA, and G. Bacon (STScI)

COS detected the heavy elements carbon and silicon in the planet's super-hot, 2,000-degree-Fahrenheit atmosphere. This detection revealed the parent star is heating the entire atmosphere, dredging up the heavier elements and allowing them to escape the planet.

The COS data also showed the material leaving the planet was not all traveling at the same speed. "We found gas escaping at high velocities, with a large amount of this gas flowing toward us at 22,000 miles per hour," Linsky said. "This large gas flow is likely gas swept up by the stellar wind to form the comet-like tail trailing the planet."

Hubble's newest spectrograph has the ability to probe a planet's chemistry at ultraviolet wavelengths not accessible to ground-based telescopes. COS is proving to be an important instrument for probing the atmospheres of "hot Jupiters" like HD 209458b.

Another Hubble instrument, the Space Telescope Imaging Spectrograph (STIS), observed the planet in 2003. The STIS data showed an active, evaporating atmosphere, and a comet-tail-like structure was suggested as a possibility. But STIS wasn't able to obtain the spectroscopic detail necessary to show a tail, or an Earthward-moving component of the gas, during transits. The tail was detected for the first time because of the unique combination of very high ultraviolet sensitivity and good spectral resolution provided by COS.

Although this extreme planet is being roasted by its star, it won't be destroyed anytime soon. "It will take about a trillion years for the planet to evaporate," Linsky said.

The results appeared in the July 10 issue of The Astrophysical Journal.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc. in Washington, D.C.

For more information visit http://www.nasa.gov/mission_pages/hubble/science/planet-tail.html

Atlantis' Crew Celebrates Charitable Strides with Commemorative Cargo

There are lots of ways for an everyday item to take on a special significance, but few work better than carrying that item into space.

The crew of STS-132 aims to make scores of objects already precious in their meaning more inspirational by taking them on this mission to the International Space Station.

A lapel pin from the Susan G. Komen Foundation’s “Race for a Cure,” for example, will be tucked inside an Atlantis locker. A green and black rubber wristband from Eli’s Army Cancer Survivors also is making the trip, along with a wristband from Team G Force Cancer Survivors.

There also are mementos from several other organizations inside Atlantis. A teddy bear from the Cleft Palate Foundation of Chapel Hill, N.C., a lapel pin from the Alzheimer’s Association of Chicago, and flags from the Juvenile Diabetes Foundation International and Make-A-Wish Foundation will be flown into orbit.

A box of commemorative items for NASA was packed inside space shuttle Atlantis for the STS-132 mission. Photo credit: NASA

Lapel pins and similar-sized commemoratives often are carried because they are small and lightweight, but their symbolism can be immense. The crew tucked a pin from the "Imagine There's No Hunger" campaign, for example, into the flight kit.

There also is room for bulkier items including banners, shirts and jerseys. For instance, Atlantis astronauts are taking a red T-shirt from the charity organization Save the Children.

The astronauts also are carrying several other lighthearted personal items, such as a 4 by 6-inch photo of Peter Pizza in Brooklyn, a piece for a Lego space shuttle and a DVD from the 2009 induction ceremony for the Rock and Roll Hall of Fame. A red squeeze ball from the business network CNBC also is along for the ride.

Such commemorative items typically reflect a personal interest or achievement by a crew member and NASA makes room for them. The expectation is that, back on Earth, many of the objects will inspire future explorers and achievements.

A pair of large boxes holding flags, patches and other items have been anchored to the support struts for the airlock in Atlantis' cargo bay. Photo credit: NASA

Atlantis and the other shuttles typically carry a host of things, such as patches, flags and other objects intended as special rewards to groups or individuals or goodwill items.

Two large boxes, outfitted for space duty, have been bolted between the braces on Atlantis’ airlock in the payload bay. The triangular containers have been packed with 3 1/2-inch American flags, some 755 small international flags and 1,200 Space Shuttle Program flags. There also are six packages of the red, white and blue flags designed for the individual orbiters.

Shuttles have carried such mementos for more than 30 years. Space shuttle Enterprise, for example, was loaded with patches and flags when it was released from a 747 on several test flights in 1977. Columbia carried a similar assortment on STS-1 and each mission thereafter has included a host of similar items.

Astronaut Gus Grissom is credited with carrying the first mementos into space when he took rolls of dimes on his Mercury flight in 1961.

Almost 50 years later, the goal and effect remain the same: to celebrate and inspire exploration.

For more information visit http://www.nasa.gov/mission_pages/shuttle/behindscenes/whatsgoingup132.html

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X-15 Pilot Robert White Dies

On July 17, 1962, Major Robert White flew the X-15 to an altitude of 314,750 feet, or 59 miles, becoming the first "winged astronaut." He was the first to fly at Mach 4, Mach 5 and Mach 6; he was the first to fly a winged vehicle into space. After a career of 'firsts' White died on March 17, 2010.

White was one of the initial pilots selected for the X-15 program, representing the Air Force in the joint program with NASA, the Navy, and North American Aviation. Between April 13, 1960, and Dec. 14, 1962, he made 16 flights in the rocket-powered aircraft.

His July 17, 1962, flight to an altitude of 314,750 feet set a world record. This was 59.6 miles, significantly higher than the 50 miles the Air Force accepted as the beginning of space, qualifying White for astronaut wings. The X-15 rocket-powered aircraft were built by North American Aviation and developed to provide in-flight information and data on aerodynamics, structures, flight controls and the physiological aspects of high-speed, high-altitude flight.

X-15 with test pilot Major Robert M. White. Credit: NASA.

A follow-on program used the aircraft as testbeds to carry various scientific experiments beyond the Earth's atmosphere on a repeated basis. Information gained from the highly successful X-15 program contributed to the development of the Mercury, Gemini and Apollo manned spaceflight programs, and also the space shuttle program. The X-15s made a total of 199 flights and the first aircraft X-15-1, serial number 56-6670, is now located at the National Air and Space Museum in Washington, D.C.

According to an article by Al Hallonquist, White's achievements as an X-15 pilot "allowed him to become the fifth American to attain astronaut wings and only the second Air Force pilot to do this."

White retired from the Air Force as a Major General.

For more information visit http://www.nasa.gov/topics/aeronautics/features/robert-white.html

New Science Findings From Messenger's Third Mercury Flyby

> Click for press release

Presenter #1 - Sean Solomon , MESSENGER Principal Investigator,
The Carnegie Institution of Washington, Washington, D.C.

Image 1.1


A MESSENGER color observation of Mercury obtained as the spacecraft approached the planet for its third and final flyby on 29 September 2009. The 1000, 700, and 430 nm filters were combined in red, green, and blue to create this color image (approximately 5 km/pixel resolution), the last that will be acquired until MESSENGER goes into orbit around Mercury in March of 2011. Only 6% of Mercury's surface in this image had not been viewed previously by spacecraft, and most of the measurements made by MESSENGER's other instruments during this flyby were made prior to closest approach. The observations nonetheless revealed fresh surprises.

Presenter #2 - Ronald J. Vervack, Jr., MESSENGER Participating Scientist,
The Johns Hopkins University Applied Physics Laboratory, Laurel, Md.

Image 2.1


Illustration of the major source and loss processes that generate and maintain Mercury’s exosphere. The panels on the left summarize the three primary sources of exospheric material. Photon-stimulated desorption occurs when solar photons excite surface-bound atoms or molecules, releasing them to the exosphere. Sunlight also heats the surface, causing atoms and molecules to evaporate. These are both low-energy processes, so most of the released material reaches only low altitudes and usually returns to the surface. Ion sputtering occurs when ions from the solar wind or Mercury’s magnetosphere impact the surface, “knocking off” atoms and molecules. Meteoroid vaporization occurs when incoming meteoroids, generally small dust particles, impact Mercury’s surface at high speeds, causing the surface material to vaporize. Both ion sputtering and meteoroid vaporization are high-energy processes and the released material can reach high altitudes. All the material in the exosphere is accelerated in the anti-sunward direction by radiation pressure; atoms and molecules at high enough altitudes for this force to overcome the gravitational influence of the planet enter Mercury’s neutral tail. Neutral constituents in the tail either escape the Mercury system or are ionized by solar radiation. The ionized material can also escape along open magnetic field lines but some of the ions are returned to the surface by Mercury’s magnetosphere.

Image 2.2



Comparison of neutral sodium observed during MESSENGER’s second and third Mercury flybys. The left panel shows that emission from neutral sodium in Mercury’s tail, which extends away from the planet in the anti-sunward direction, was a factor of 10-20 less than during the second flyby. This difference is due to variations in the pressure that solar radiation exerts on the sodium as Mercury moves in its orbit. During the third flyby, the net effect of radiation pressure was small, and the sodium atoms released from Mercury’s surface were not accelerated anti-sunward as they were during the first two flybys, resulting in a diminished sodium tail. These predictable changes lead to what are effectively “seasonal” effects on the distribution of exospheric species.

Image 2.3


Comparison of the neutral sodium observed during the second and third Mercury flybys to models. The top left and right panels show the same images as in Image 2.2, but the color scale for the third flyby has been stretched to show the distribution of sodium more clearly. As in previous flybys, the distinct north and south enhancements in the emission that result from material being sputtered from the surface at high latitudes on the dayside are seen. The lower two panels show Monte Carlo models of the sodium abundance in Mercury’s exosphere for conditions similar to those during the two flybys. These models illustrate that the “disappearance” of Mercury’s neutral sodium tail is consistent with the change in conditions. Observations of the sodium exosphere and tail throughout Mercury’s orbit during MESSENGER’s orbital mission phase will enable such “seasonal” effects to be studied. Refinement of models similar to these will lead to an improved understanding of the source and loss processes and their variations among Mercury’s different exospheric “seasons.”

Image 2.4


Observations of calcium and magnesium in Mercury’s neutral tail during the third MESSENGER flyby. The distribution of neutral calcium in the tail appears to be centered near the equatorial plane and the emission rapidly decreases to the north and south as well as in the anti-sunward direction. In contrast, the distribution of magnesium in the tail exhibits several strong peaks in emission and a slower decrease in the north, south, and anti-sunward directions. These distributions are similar to those seen during the second flyby, but the densities were higher during the third flyby, a different “seasonal” variation than for sodium. Studying the changes of the “seasons” for a range of species during MESSENGER’s orbital mission phase will be key to quantifying the processes that generate and maintain the exosphere and transport volatile material within the Mercury environment.

Image 2.5


First observations of emission from ionized calcium in Mercury’s tail region compared with simultaneous observations of neutral calcium. Neutral calcium is rapidly converted to ionized calcium by sunlight, explaining the generally rapid decrease of neutral calcium away from the planet. The high degree of correlation between the two observed distributions reflects the rapid conversion of neutrals to ions and demonstrates that ionized calcium represents a significant fraction of the overall calcium abundance. Simultaneous measurement of the abundances of calcium neutrals and ions is therefore necessary to measure the total calcium abundance in Mercury’s exosphere accurately. This situation is in contrast to that for sodium and magnesium, which are ionized much more slowly. The significantly longer lifetime for neutral magnesium may explain why its abundance is more widely distributed in the tail region when compared to calcium (Image 2.4).

Presenter #3 - David J. Lawrence, MESSENGER Participating Scientist,
The Johns Hopkins University Applied Physics Laboratory, Laurel, Md.

Image 3.1


Schematic view of Mercury’s interior showing its large, iron-rich core, which constitutes at least ~60% of the planet’s mass. Observations from Earth and by MESSENGER at visible and near-infrared wavelengths have shown that Mercury’s surface has a very low concentration of iron (Fe) in silicate minerals, leading to the common view that Mercury’s surface and crust are generally low in iron. A puzzle for investigations of Mercury’s formation and evolution is how a planet with such a large Fe-rich core could form with such an Fe-poor surface?

Image 3.2

Areas on Mercury’s surface measured with the MESSENGER Neutron Spectrometer (NS) during the first and third Mercury flybys (M1 and M3, respectively) are shown as circles. The spacecraft ground tracks for M1 and M3 are indicated by the black and blue lines, respectively. A mosaic of Mercury’s surface in cylindrical projection is shown as background. The inset is a schematic illustration of how thermal neutrons are used to probe the iron (Fe) and titanium (Ti) content of Mercury’s surface. Fe and Ti capture thermal neutrons very efficiently, so low fluxes of thermal neutrons indicate high abundances of these elements.

Image 3.3

Modeled and measured neutron counting rates for M1. The solid lines show predicted neutron counting rates for three different composition models: low Fe and Ti (blue), high Fe and Ti (red), and highest Fe and Ti (green). The low Fe and Ti model similar in composition to the lunar highlands. The high and highest Fe and Ti models are similar in composition to lunar basalts from Mare Fecunditatis (Luna 16) and Mare Tranquillitatis (Apollo 11), respectively. A spacecraft maneuver was executed at 19:00 UTC that enabled the NS to measure an enhanced signal of thermal neutrons. The NS data (black circles) show that Mercury’s surface fits the model with high Fe and Ti abundances, in contrast to previous ideas that Mercury’s surface is low in Fe and Ti.

Image 3.4
Modeled and measured neutron counts for M3. While the data stop prior to 21:50 UTC because of the spacecraft safing event that shut off all data collection, enough NS data were returned to again show that Mercury’s surface fits the model with high abundances of Fe and Ti. These results from both M1 and M3 demonstrate that Mercury’s surface has a significantly higher Fe+Ti content than was previously appreciated. Models for Mercury’s formation and crustal evolution must be revised to take this finding into account.


Presenter #4 - Brett Denevi, MESSENGER Imaging Team member and Postdoctoral Researcher,
Arizona State University, Tempe, Ariz.

Image 4.1


Combined image coverage map of Mercury after Mariner 10 and MESSENGER’s first two flybys of Mercury. Although 90% of Mercury’s surface had been imaged after MESSENGER’s second flyby, there was a gap in longitudinal coverage centered at about 60° E.

Image 4.2


Image coverage map of Mercury after the third MESSENGER flyby. The approach trajectory of the third flyby allowed the longitudinal gap to be seen as a part of a mosaic created from 58 images. The nearly complete (98%) coverage now leaves unimaged only portions of the polar regions before MESSENGER is placed into orbit about Mercury in March 2011. Despite the now-complete equatorial coverage, it is worth noting that illumination conditions were far from uniform during the various flybys, and images of many areas did not favor observations of surface texture and topography. Imaging of these areas from orbit under more optimum lighting conditions and higher resolution will improve our understanding of the evolution of Mercury’s surface.

Image 4.3


Selected features revealed during MESSENGER’s third flyby. This enhanced-color view was created with a statistical technique that highlights subtle color variations seen in the 11 filters of MESSENGER’s wide-angle camera that are often related to composition. Merged with images from the higher-resolution narrow-angle camera, the two sets of observations tell the story of the geology of the area and the compositional differences of the features observed. This region, viewed in detail for the first time during the third flyby, appears to have experienced a high level of volcanic activity. The bright yellow area near the top right is centered on a rimless depression (Image 4.4) that is a candidate site for an explosive volcanic vent. The 290-km-diameter double-ring basin in the center of the image has a smooth interior (Image 4.5) that may be the result of effusive volcanism. Smooth plains, thought to be a result of earlier episodes of volcanic activity, cover much of the surrounding area. Image resolution is 1 km/pixel.

Image 4.4


Detailed view of the irregular depression in Image 4.3. This region of high reflectance was just barely seen on the limb during MESSENGER’s second flyby, but without enough detail to characterize it as anything other than a bright spot. A more favorable viewing angle reveals this bright spot to be an irregular rimless depression approximately 30 km across surrounded by highly reflective material. Its features are distinctly different from those of impact craters and, though its origin remains ambiguous, it is suspected to be volcanic. The high-reflectance halo surrounding this enigmatic feature is distinct in color (see Image 4.3) and may represent a pyroclastic deposit greater than 150 km in diameter.

Image 4.5


Detailed view of the interior of the double-ring basin in Image 4.3. This spectacular 290-km-diameter double-ring basin seen in detail for the first time during MESSENGER’s third flyby of Mercury bears a striking resemblance to the Raditladi basin, observed during the first flyby. This still-unnamed basin is remarkably well preserved and appears to have formed relatively recently, compared with most basins on Mercury. The low numbers of superposed impact craters and marked differences in color across the basin suggest that the smooth area within the innermost ring may be the site of some of the most recent volcanism on Mercury. MESSENGER’s final flyby of Mercury brings to the fore the importance of the orbital phase of the mission that begins 18 March 2011!

Related Links:

> Presenter bios
> JHUAPL's Messenger site

Contact Information:

Paulette Campbell
The Johns Hopkins University Applied Physics Laboratory
Laurel, Maryland
Phone: 240.228.6792

Dwayne Brown
NASA Headquarters
Washington, DC
Phone: 202.358.1726/3895

Tina McDowell
Carnegie Institution of Washington
Washington, DC
Phone: 202.939.1120

Event Information:

The NASA MESSENGER Science Update will take place on Tuesday, November 3, 2009, at 1 p.m. EST. Reporters may ask questions from participating NASA locations. The briefing also will be streamed live on NASA's Web site at: http://www.nasa.gov.

For more information visit http://www.nasa.gov/mission_pages/messenger/media/flyby20091029.html

MESSENGER Spacecraft Reveals More Hidden Territory on Mercury

WASHINGTON -- A NASA spacecraft's third and final flyby of Mercury gives scientists, for the first time, an almost complete view of the planet's surface and provides new scientific findings about this relatively unknown world.

The Mercury Surface, Space Environment, Geochemistry and Ranging spacecraft, known as MESSENGER, flew by Mercury on Sept. 29. The probe completed a critical gravity assist to remain on course to enter into orbit around Mercury in 2011. Despite shutting down temporarily because of a power system switchover during a solar eclipse, the spacecraft's cameras and instruments collected high-resolution and color images unveiling another 6 percent of the planet's surface never before seen at close range.

Approximately 98 percent of Mercury's surface now has been imaged by NASA spacecraft. After MESSENGER goes into orbit around Mercury, it will see the polar regions, which are the only unobserved areas of the planet.

"Although the area viewed for the first time by spacecraft was less than 350 miles across at the equator, the new images reminded us that Mercury continues to hold surprises," said Sean Solomon, principal investigator for the mission and director of the Department of Terrestrial Magnetism at the Carnegie Institution of Washington.

Many new features were revealed during the third flyby, including a region with a bright area surrounding an irregular depression, suspected to be volcanic in origin. Other images revealed a double-ring impact basin approximately 180 miles across. The basin is similar to a feature scientists call the Raditladi basin, which was viewed during the probe's first flyby of Mercury in January 2008.

"This double-ring basin, seen in detail for the first time, is remarkably well preserved," said Brett Denevi, a member of the probe's imaging team and a postdoctoral researcher at Arizona State University in Tempe. "One similarity to Raditladi is its age, which has been estimated to be approximately one billion years old. Such an age is quite young for an impact basin, because most basins are about four times older. The inner floor of this basin is even younger than the basin itself and differs in color from its surroundings. We may have found the youngest volcanic material on Mercury."

One of the spacecraft's instruments conducted its most extensive observations to date of Mercury's exosphere, or thin atmosphere, during this encounter. The flyby allowed for the first detailed scans over Mercury's north and south poles. The probe also has begun to reveal how Mercury's atmosphere varies with its distance from the sun.

"A striking illustration of what we call 'seasonal' effects in Mercury's exosphere is that the neutral sodium tail, so prominent in the first two flybys, is 10 to 20 times less intense in emission and significantly reduced in extent," says participating scientist Ron Vervack, of the Johns Hopkins University Applied Physics Laboratory, or APL, in Laurel, Md. "This difference is related to expected variations in solar radiation pressure as Mercury moves in its orbit and demonstrates why Mercury's exosphere is one of the most dynamic in the solar system."

The observations also show that calcium and magnesium exhibit different seasonal changes than sodium. Studying the seasonal changes in all exospheric constituents during the mission orbital phase will provide key information on the relative importance of the processes that generate, sustain, and modify Mercury's atmosphere.

The third flyby also revealed new information on the abundances of iron and titanium in Mercury's surface materials. Earlier Earth and spacecraft-based observations showed that Mercury's surface has a very low concentration of iron in silicate minerals, a result that led to the view that the planet's crust is generally low in iron.

"Now we know Mercury's surface has an average iron and titanium abundance that is higher than most of us expected, similar to some lunar mare basalts," says David Lawrence, an APL participating mission scientist.

The spacecraft has completed nearly three-quarters of its 4.9-billion-mile journey to enter orbit around Mercury. The full trip will include more than 15 trips around the sun. In addition to flying by Mercury, the spacecraft flew past Earth in August 2005 and Venus in October 2006 and June 2007.

The spacecraft was designed and built by APL. The mission is managed and operated by APL for NASA's Science Mission Directorate in Washington.

For more information about the mission, visit:

http://www.nasa.gov/messenger

And http://www.nasa.gov/home/hqnews/2009/nov/HQ_09-257_Messenger.html

NASA to Release New Images and Findings from Third Mercury Flyby

WASHINGTON -- NASA will host a media teleconference at 1 p.m. EST on Tuesday, Nov. 3, to announce scientific findings and release new images from the third and final flyby of Mercury by the Mercury Surface, Space Environment, Geochemistry and Ranging spacecraft, known as MESSENGER.

The probe's cameras and instruments collected high-resolution and color images of the planet on Sept. 29, unveiling another six percent of Mercury's surface never before seen by a spacecraft.

The briefing participants are:

• Sean Solomon, principal investigator, Carnegie Institution of Washington
• Ronald J. Vervack, Jr., participating scientist, The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md.
• David J. Lawrence, participating scientist, APL
• Brett Denevi, imaging team member and postdoctoral researcher, Arizona State University, Tempe

To participate in the teleconference, reporters should e-mail Sonja Alexander at:

sonja.r.alexander@nasa.gov

Audio of the teleconference will be streamed live at:

http://www.nasa.gov/newsaudio

At the beginning of the briefing, related images will be available online at:

http://messenger.jhuapl.edu/news_room

And For more information visit http://www.nasa.gov/home/hqnews/2009/oct/HQ_M09-208_Messenger_telecon.html