vendredi 29 juin 2012

Chinese Space Capsule With 3 Taïkonauts Returns to Earth










CNSA - China National Space Administration logo.

June 29. 2012

Three Chinese Taïkonauts returned to Earth Thursday (June 28) after 13 days in space on a historic mission that made their country only the third nation ever to successfully dock a manned spacecraft to another in orbit.

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China's Shenzhou-9 spacecraft returns to Earth

China's Shenzhou 9 space capsule landed at about10 p.m. EDT (10 a.m. Friday, June 29 Beijing time) in Inner Mongolia, an autonomous region of the People's Republic of China. To prepare for their journey home, the space crew — which included China's first female Taïkonaut Liu Yang — separated the Shenzhou 9 capsule its target, the Tiangong 1 prototype space module, on Wednesday (June 27).


Image above: This photograph of a China CCTV broadcast shows the Shenzhou 9 space capsule lying on its side after landing in an autonomous region of China in Inner Mongolia on June 29, 2012 Beijing time (10 p.m. June 28 EDT) to end a 13-day mission to the Tiangong 1 space lab module. Credit: CCTV.

Their landing was broadcast live on China's state-run CCTV television network, showing the capsule streaking through the atmosphere like a meteor, deploying its main parachute, then making the final landing and rolling over on its side in a rough touchdown.

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China's Shenzhou-9 spacecraft undocking & returns to Earth

"We fulfilled the first manned manual docking," mission commander Jing Haipeng told CCTV reporters after exiting the Shenzhou 9 capsule. His comments in Chinese were translated into English by CCTV. "For the country and people all across the country, thank you for your concerns." 
Jing and crewmates Liu Yang and Liu Wang appeared to be in good health after their space mission. The trio wore broad smiles and waved to cameras after leaving their spacecraft, but did sit in reclined chairs to help ease their adaptation back to Earth's gravity after nearly two weeks in weightlessness.


Image above: Chinese Taïkonaut Jing Haipeng, commander of the Shenzhou 9 mission, salutes after exiting the space capsule following landing in Inner Mongolia autonomous mission on June 28, 2012. Credit: China Central Television/CCTV.

Shortly after the landing, China's Premier Wen Jiabao proclaimed the Shenzhou 9 mission a complete success.

"This manned docking mission of Tiangong 1 and Shenzhou 9 marks a large milestone, a major breakthrough for China to master the space docking technology," Wen said while reading a statement. "And also, it marks a decisive step forward on China's second step on its space strategy."

For more information about CNSA, visit: http://www.cnsa.gov.cn/n615709/cindex.html

Images (mentioned), Videos, Text, Credits: AP / China Central Television / CCTV / IBTime / CNSA.

Best regards, Orbiter.ch

Has the Speediest Pulsar Been Found?













NASA - Chandra X-ray Observatory patch / ESA - XMM Newton Mission patch.

June 29, 2012

Researchers using three different telescopes -- NASA's Chandra X-ray Observatory and ESA's XMM-Newton in space, and the Parkes radio telescope in Australia -- may have found the fastest moving pulsar ever seen.


The evidence for this potentially record-breaking speed comes, in part, from the features highlighted in this composite image. X-ray observations from Chandra (green) and XMM-Newton (purple) have been combined with infrared data from the 2MASS project and optical data from the Digitized Sky Survey (colored red, green and blue, but appearing in the image as white).

The large area of diffuse X-rays seen by XMM-Newton was produced when a massive star exploded as a supernova, leaving behind a debris field, or supernova remnant known as SNR MSH 11-16A. Shocks waves from the supernova have heated surrounding gas to several million degrees Kelvin, causing the remnant to glow brightly in X-rays.

The Chandra image shown in the inset ("X-ray close-up") reveals a comet-shaped X-ray source well outside the boundary of the supernova remnant. This source consists of a point-like object with a long tail trailing behind it for about 3 light years. The bright star nearby and also the one in SNR MSH11-16A are both likely to be foreground stars unrelated to the supernova remnant.

The point-like X-ray source was discovered by the International Gamma-Ray Astrophysics Laboratory, or INTEGRAL, and is called IGR J11014-6103 (or IGR J11014 for short). It may be a rapidly spinning, super-dense star (known as a "pulsar", a type of neutron star) that was ejected during the explosion. If so, it is racing away from the center of the supernova remnant at millions of miles per hour.

The favored interpretation for the tail of X-ray emission is that a pulsar wind nebula, that is, a "wind" of high-energy particles produced by the pulsar, has been swept behind a bow shock created by the pulsar's high speed. (A similar case was seen in another object known as PSR B1957+20 [http://chandra.harvard.edu/photo/2003/b1957/closer_look.html].

The elongated emission is pointing towards the center of MSH 11-61A where the pulsar would have been formed, supporting the idea that the Chandra image is of a pulsar wind nebula and its bow shock. Another interesting feature of the Chandra image, also seen with XMM-Newton, is the faint X-ray tail extending to the top-right. The cause of this feature is unknown, but similar tails have been seen from other pulsars that also do not line up with the pulsar's direction of motion.

Based on earlier observations, astronomers estimate that the age of MSH 11-61A is approximately 15,000 years, and it lies at a distance of about 30,000 light years away from Earth. Combining these values with the distance that the pulsar has appeared to have traveled from the center of the MSH 11-61A, astronomers estimate that IGR J11014 is moving at a speed between 5.4 million and 6.5 million miles per hour.

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The only other neutron star associated with a supernova remnant that may rival this in speed is the candidate found in the supernova remnant known as G350.1-0.3. The speed of the neutron star candidate in this system is estimated to lie between 3 and 6 million miles per hour (http://chandra.harvard.edu/photo/2012/g350/). The high speeds estimated for both IGR J11014 and the neutron star candidate in G350.1-0.3 are preliminary and need to be confirmed. If they are confirmed, explaining the high speeds of the neutron star presents a severe challenge to existing models for supernova explosions.

One important caveat in the conclusion that IGR J11014 may be the fastest moving pulsar is that pulsations have not been detected in it during a search with the Commonwealth Scientific and Industrial Research Organization (CSIRO) Parkes radio telescope. This non-detection is not surprising for a pulsar located about 30,000 light years away.

However, there are other pieces of evidence that support the pulsar interpretation. First, the lack of detection of a counterpart to the X-ray source in optical or infrared images supports the idea that it is a pulsar, since such objects are very faint at these wavelengths. Also, there are no apparent differences in the brightness of the source between XMM-Newton observations in 2003 and the Chandra observations in 2011, behavior that is expected if IGR J11014 is a pulsar. Finally, the X-ray spectrum of the source, that is, its signature in energy, is similar to what astronomers expect to see for a pulsar.

These results were published in the May 10, 2012 issue of The Astrophysical Journal Letters. The authors were John Tomsick and Arash Bodaghee (University of California, Berkeley), Jerome Rodriguez and Sylvain Chaty (University of Paris, CEA Saclay), Fernando Camilo (Columbia University), Francesca Fornasini (UC Berkeley), and Farhid Rahoui (Harvard-Smithsonian Center for Astrophysics).

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

Read more/access all images: http://chandra.harvard.edu/photo/2012/igrj11014/

Chandra's Flickr photoset: http://www.flickr.com/photos/nasamarshall/sets/72157606205297786/with/7268281472/

Image, Video, Credits: X-ray: NASA / CXC / UC Berkeley / J. Tomsick et al and ESA / XMM-Newton; Optical: DSS, 2MASS / UMass/IPAC-Caltech / NASA / NSF.

Text Credits: NASA / Marshall Space Flight Center / Janet Anderson / Chandra X-ray Center / Megan Watzke.

Greetings, Orbiter.ch

jeudi 28 juin 2012

Hubble, Swift Detect First-Ever Changes in an Exoplanet Atmosphere














ESA - Hubble Space Telescope Logo / NASA - SWIFT Mission patch.

June 28, 2012

An international team of astronomers using data from NASA's Hubble Space Telescope has made an unparalleled observation, detecting significant changes in the atmosphere of a planet located beyond our solar system.

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Stellar Flare Sweeps Up Exoplanet's Atmosphere

The exoplanet HD 189733b lies so near its star that it completes an orbit every 2.2 days. In late 2011, NASA's Hubble Space Telescope found that the planet's upper atmosphere was streaming away at speeds exceeding 300,000 mph. Just before the Hubble observation, NASA's Swift detected the star blasting out a strong X-ray flare, one powerful enough to blow away part of the planet's atmosphere.

The scientists conclude the atmospheric variations occurred in response to a powerful eruption on the planet's host star, an event observed by NASA's Swift satellite.

"The multiwavelength coverage by Hubble and Swift has given us an unprecedented view of the interaction between a flare on an active star and the atmosphere of a giant planet," said lead researcher Alain Lecavelier des Etangs at the Paris Institute of Astrophysics (IAP), part of the French National Scientific Research Center located at Pierre and Marie Curie University in Paris.

The exoplanet is HD 189733b, a gas giant similar to Jupiter, but about 14 percent larger and more massive. The planet circles its star at a distance of only 3 million miles, or about 30 times closer than Earth's distance from the sun, and completes an orbit every 2.2 days. Its star, named HD 189733A, is about 80 percent the size and mass of our sun.


This artist's rendering illustrates the evaporation of HD 189733b's atmosphere in response to a powerful eruption from its host star. NASA's Hubble Space Telescope detected the escaping gases and NASA's Swift satellite caught the stellar flare. (Credit: NASA's Goddard Space Flight Center).

Astronomers classify the planet as a "hot Jupiter." Previous Hubble observations show that the planet's deep atmosphere reaches a temperature of about 1,900 degrees Fahrenheit (1,030 C).

HD 189733b periodically passes across, or transits, its parent star, and these events give astronomers an opportunity to probe its atmosphere and environment. In a previous study, a group led by Lecavelier des Etangs used Hubble to show that hydrogen gas was escaping from the planet's upper atmosphere. The finding made HD 189733b only the second-known "evaporating" exoplanet at the time.

The system is just 63 light-years away, so close that its star can be seen with binoculars near the famous Dumbbell Nebula. This makes HD 189733b an ideal target for studying the processes that drive atmospheric escape.

"Astronomers have been debating the details of atmospheric evaporation for years, and studying HD 189733b is our best opportunity for understanding the process," said Vincent Bourrier, a doctoral student at IAP and a team member on the new study.

When HD 189733b transits its star, some of the star's light passes through the planet's atmosphere. This interaction imprints information on the composition and motion of the planet's atmosphere into the star's light.


Image above: Swift's Ultraviolet/Optical Telescope captured this view of HD 189733b's star on Sept. 14, 2011. The image is 6 arcminutes across. Credit: NASA/Swift/Stefan Immler.

In April 2010, the researchers observed a single transit using Hubble's Space Telescope Imaging Spectrograph (STIS), but they detected no trace of the planet's atmosphere. Follow-up STIS observations in September 2011 showed a surprising reversal, with striking evidence that a plume of gas was streaming away from the exoplanet.

The researchers determined that at least 1,000 tons of gas was leaving the planet's atmosphere every second. The hydrogen atoms were racing away at speeds greater than 300,000 mph. The findings will appear in an upcoming issue of the journal Astronomy & Astrophysics.

Because X-rays and extreme ultraviolet starlight heat the planet's atmosphere and likely drive its escape, the team also monitored the star with Swift's X-ray Telescope (XRT). On Sept. 7, 2011, just eight hours before Hubble was scheduled to observe the transit, Swift was monitoring the star when it unleashed a powerful flare. It brightened by 3.6 times in X-rays, a spike occurring atop emission levels that already were greater than the sun's.


Image above: Strong X-ray emission makes the host star of HD 189733b stand out in this view from Swift's X-Ray Telescope. The image combines data from Sept. 13 and 14, 2011, and is 6 arcminutes across. Credit: NASA/Swift/Stefan Immler.

"The planet's close proximity to the star means it was struck by a blast of X-rays tens of thousands of times stronger than the Earth suffers even during an X-class solar flare, the strongest category," said co-author Peter Wheatley, a physicist at the University of Warwick in England.

After accounting for the planet's enormous size, the team notes that HD 189733b encountered about 3 million times as many X-rays as Earth receives from a solar flare at the threshold of the X class.

Hubble is a project of international cooperation between NASA and the European Space Agency. Swift is operated in collaboration with several U.S. institutions and partners in the United Kingdom, Italy, Germany and Japan. NASA's Goddard Space Flight Center in Greenbelt, Md., manages both missions.

For more information about Swift, visit: http://www.nasa.gov/swift

For more information about Hubble, visit: http://www.nasa.gov/hubble
and http://www.spacetelescope.org/

Images (mentioned), Video, Text, Credits: NASA / ESA / Goddard Space Flight Center.

Cheers, Orbiter.ch

Cassini Finds Likely Subsurface Ocean on Saturn Moon












NASA / ESA - Cassini Mission to Saturn & Titan patch.

June 28, 2012

Data from NASA's Cassini spacecraft have revealed Saturn's moon Titan likely harbors a layer of liquid water under its ice shell.


This artist's concept shows a possible scenario for the internal structure of Titan, as suggested by data from NASA's Cassini spacecraft. Image credit: A. Tavani.

Researchers saw a large amount of squeezing and stretching as the moon orbited Saturn. They deduced that if Titan were composed entirely of stiff rock, the gravitational attraction of Saturn would cause bulges, or solid "tides," on the moon only 3 feet (1 meter) in height. Spacecraft data show Saturn creates solid tides approximately 30 feet (10 meters) in height, which suggests Titan is not made entirely of solid rocky material. The finding appears in today's edition of the journal Science.

"Cassini's detection of large tides on Titan leads to the almost inescapable conclusion that there is a hidden ocean at depth," said Luciano Iess, the paper's lead author and a Cassini team member at the Sapienza University of Rome, Italy. "The search for water is an important goal in solar system exploration, and now we've spotted another place where it is abundant."

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Squeezing and Stretching Titan

Titan takes only 16 days to orbit Saturn, and scientists were able to study the moon's shape at different parts of its orbit. Because Titan is not spherical, but slightly elongated like a football, its long axis grew when it was closer to Saturn. Eight days later, when Titan was farther from Saturn, it became less elongated and more nearly round. Cassini measured the gravitational effect of that squeeze and pull.

Scientists were not sure Cassini would be able to detect the bulges caused by Saturn's pull on Titan. By studying six close flybys of Titan from Feb. 27, 2006, to Feb. 18, 2011, researchers were able to determine the moon's internal structure by measuring variations in the gravitational pull of Titan using data returned to NASA's Deep Space Network (DSN).

"We were making ultrasensitive measurements, and thankfully Cassini and the DSN were able to maintain a very stable link," said Sami Asmar, a Cassini team member at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "The tides on Titan pulled up by Saturn aren't huge compared to the pull the biggest planet, Jupiter, has on some of its moons. But, short of being able to drill on Titan's surface, the gravity measurements provide the best data we have of Titan's internal structure."


Image above: The colorful globe of Saturn's largest moon, Titan, passes in front of the planet and its rings in this true color snapshot from NASA's Cassini spacecraft. Image credit: NASA/JPL-Caltech/Space Science Institute.

An ocean layer does not have to be huge or deep to create these tides. A liquid layer between the external, deformable shell and a solid mantle would enable Titan to bulge and compress as it orbits Saturn. Because Titan's surface is mostly made of water ice, which is abundant in moons of the outer solar system, scientists infer Titan's ocean is likely mostly liquid water.

On Earth, tides result from the gravitational attraction of the moon and sun pulling on our surface oceans. In the open oceans, those can be as high as two feet (60 centimeters). While water is easier to move, the gravitational pulling by the sun and moon also causes Earth's crust to bulge in solid tides of about 20 inches (50 centimeters).

The presence of a subsurface layer of liquid water at Titan is not itself an indicator for life. Scientists think life is more likely to arise when liquid water is in contact with rock, and these measurements cannot tell whether the ocean bottom is made up of rock or ice. The results have a bigger implication for the mystery of methane replenishment on Titan.

"The presence of a liquid water layer in Titan is important because we want to understand how methane is stored in Titan's interior and how it may outgas to the surface," said Jonathan Lunine, a Cassini team member at Cornell University, Ithaca, N.Y. "This is important because everything that is unique about Titan derives from the presence of abundant methane, yet the methane in the atmosphere is unstable and will be destroyed on geologically short timescales."

A liquid water ocean, "salted" with ammonia, could produce buoyant ammonia-water liquids that bubble up through the crust and liberate methane from the ice. Such an ocean could serve also as a deep reservoir for storing methane.


Image above: The shape of the moon changes along its orbit because of the varying tidal pull from Saturn such that it is stretched into a rugby-ball shape at its closest point to the gas giant and is more spherical at its most distant point. The change in shape causes a redistribution of mass in the moon and therefore a change in the gravity field, which is measured by Cassini in the form of the change in acceleration of the spacecraft as tracked by microwave radio links with the ground antennas of NASA’s Deep Space Network.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The mission is managed by JPL for NASA's Science Mission Directorate in Washington. DSN, also managed by JPL, 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. Cassini's radio science team is based at Wellesley College in Massachusetts. JPL is a division of the California Institute of Technology in Pasadena.

For more information about the mission, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov and http://www.esa.int/esaMI/Cassini-Huygens/

Images (mentioned), Video, Text, Credits: NASA / ESA / Dwayne Brown / JPL / Jia-Rui Cook / JPL-Caltech / Space Science Institute.

Greetings, Orbiter.ch

mercredi 27 juin 2012

NuSTAR Mission Status Report












NASA - NuSTAR Mission patch.

June 27, 2012

After deploying its mast, the NuSTAR observatory began a series of checkout procedures. The procedures include measuring the alignment of all the components of the spacecraft systems that determine the pointing direction of the telescope, and bringing the X-ray digital cameras online. The team tuned up the spacecraft so that the long telescope can be pointed accurately at different locations in the sky, and they are completing the process of making the pointing direction accurate.


Artist's concept showing NASA's NuSTAR mission orbiting Earth. Image credit: NASA/JPL-Caltech. Image credit: NASA/JPL-Caltech.

The X-ray digital cameras were turned on so that the team can tune up their performance. The cameras are operating well. A calibration source was inserted in the field, and it has been determined that the cameras are accurately measuring the energy of incoming X-rays. The team is preparing for the first-light images on Thursday.

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

Image (mentioned), Credits: NASA / Text Written by NuSTAR Principal Investigator Fiona Harrison.
California Institute of Technology in Pasadena.

Greetings, Orbiter.ch

New Way of Probing Exoplanet Atmospheres












ESO - European Southern Observatory logo.

27 June 2012

Tau Boötis b revealed

Artist’s impression of the exoplanet Tau Boötis b

For the first time a clever new technique has allowed astronomers to study the atmosphere of an exoplanet in detail — even though it does not pass in front of its parent star. An international team has used ESO’s Very Large Telescope to directly catch the faint glow from the planet Tau Boötis b. They have studied the planet’s atmosphere and measured its orbit and mass precisely for the first time — in the process solving a 15-year old problem. Surprisingly, the team also finds that the planet’s atmosphere seems to be cooler higher up, the opposite of what was expected. The results will be published in the 28 June 2012 issue of the journal Nature.

The planet Tau Boötis b [1] was one of the first exoplanets to be discovered back in 1996, and it is still one of the closest exoplanets known. Although its parent star is easily visible with the naked eye, the planet itself certainly is not, and up to now it could only be detected by its gravitational effects on the star. Tau Boötis b is a large “hot Jupiter” planet orbiting very close to its parent star.

Like most exoplanets, this planet does not transit the disc of its star (like the recent transit of Venus). Up to now such transits were essential to allow the study of hot Jupiter atmospheres: when a planet passes in front of its star it imprints the properties of the atmosphere onto the starlight. As no starlight shines through Tau Boötis b’s atmosphere towards us, this means the planet’s atmosphere could not be studied before.

The parent star of the famous exoplanet Tau Boötis b

But now, after 15 years of attempting to study the faint glow that is emitted from hot Jupiter exoplanets, astronomers have finally succeeded in reliably probing the structure of the atmosphere of Tau Boötis b and deducing its mass accurately for the first time. The team used the CRIRES [2] instrument on the Very Large Telescope (VLT) at ESO’s Paranal Observatory in Chile. They combined high quality infrared observations (at wavelengths around 2.3 microns) [3] with a clever new trick to tease out the weak signal of the planet from the much stronger one from the parent star [4].

Lead author of the study Matteo Brogi (Leiden Observatory, the Netherlands) explains: “Thanks to the high quality observations provided by the VLT and CRIRES we were able to study the spectrum of the system in much more detail than has been possible before. Only about 0.01% of the light we see comes from the planet, and the rest from the star, so this was not easy”.

Wide-field view of the parent star of the famous exoplanet Tau Boötis b

The majority of planets around other stars were discovered by their gravitational effects on their parent stars, which limits the information that can be gleaned about their mass: they only allow a lower limit to be calculated for a planet’s mass [5]. The new technique pioneered here is much more powerful. Seeing the planet’s light directly has allowed the astronomers to measure the angle of the planet’s orbit and hence work out its mass precisely. By tracing the changes in the planet’s motion as it orbits its star, the team has determined reliably for the first time that Tau Boötis b orbits its host star at an angle of 44 degrees and has a mass six times that of the planet Jupiter in our own Solar System.

“The new VLT observations solve the 15-year old problem of the mass of Tau Boötis b. And the new technique also means that we can now study the atmospheres of exoplanets that don’t transit their stars, as well as measuring their masses accurately, which was impossible before”, says Ignas Snellen (Leiden Observatory, the Netherlands), co-author of the paper. “This is a big step forward.”

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Artist’s impression of the famous exoplanet Tau Boötis b

As well as detecting the glow of the atmosphere and measuring Tau Boötis b’s mass, the team has probed its atmosphere and measured the amount of carbon monoxide present, as well as the temperature at different altitudes by means of a comparison between the observations and theoretical models. A surprising result from this work was that the new observations indicated an atmosphere with a temperature that falls higher up. This result is the exact opposite of the temperature inversion — an increase in temperature with height — found for other hot Jupiter exoplanets [6] [7].

The VLT observations show that high resolution spectroscopy from ground-based telescopes is a valuable tool for a detailed analysis of non-transiting exoplanets’ atmospheres. The detection of different molecules in future will allow astronomers to learn more about the planet’s atmospheric conditions. By making measurements along the planet’s orbit, astronomers may even be able to track atmospheric changes between the planet’s morning and evening.

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Zooming in on the star Tau Boötis

"This study shows the enormous potential of current and future ground-based telescopes, such as the E-ELT. Maybe one day we may even find evidence for biological activity on Earth-like planets in this way”, concludes Ignas Snellen.

Notes:

[1] The name of the planet, Tau Boötis b, combines the name of the star (Tau Boötis, or τ Bootis, τ is the Greek letter “tau”, not a letter “t” ) with the letter “b” indicating that this is the first planet found around this star. The designation Tau Boötis a is used for the star itself.

[2] CRyogenic InfraRed Echelle Spectrometer

[3] At infrared wavelengths, the parent star emits less light than in the optical regime, so this is a wavelength regime favorable for separating out the dim planet’s signal.

[4] This method uses the velocity of the planet in orbit around its parent star to distinguish its radiation from that of the star and also from features coming from the Earth’s atmosphere. The same team of astronomers tested this technique before on a transiting planet, measuring its orbital velocity during its crossing of the stellar disc.

[5] This is because the tilt of the orbit is normally unknown. If the planet’s orbit is tilted relative to the line of sight between Earth and the star then a more massive planet causes the same observed back and forth motion of the star as a lighter planet in a less tilted orbit and it is not possible to separate the two effects.

[6] Thermal inversions are thought to be characterised by molecular features in emission in the spectrum, rather than in absorption, as interpreted from photometric observations of hot Jupiters with the Spitzer Space Telescope. The exoplanet HD209458b is the best-studied example of thermal inversions in the exoplanet atmospheres.

[7] This observation supports models in which strong ultraviolet emission associated to chromospheric activity — similar to the one exhibited by the host star of Tau Boötis b — is responsible for the inhibition of the thermal inversion.

More information:

This research was presented in a paper "The signature of orbital motion from the dayside of the planet τ Boötis b" to appear in the journal Nature on 28 June 2012.

The team is composed of Matteo Brogi (Leiden Observatory, the Netherlands), Ignas A. G. Snellen (Leiden Observatory), Remco J. de Kok (SRON, Utrecht, the Netherlands), Simon Albrecht (Massachusetts Institute of Technology, Cambridge, USA), Jayne Birkby (Leiden Observatory) and Ernst J. W. de Mooij (University of Toronto, Canada; Leiden Observatory).

The year 2012 marks the 50th anniversary of the founding of the European Southern Observatory (ESO). ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 40-metre-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links:

    Research paper in Nature: http://www.eso.org/public/archives/releases/sciencepapers/eso1227/eso1227.pdf

    Photos of the VLT: http://www.eso.org/public/images/archive/search/?adv=&subject_name=Very%20Large%20Telescope

    Other images taken with the VLT: http://www.eso.org/public/images/archive/search/?adv=&facility=31

ESO, La Silla, Paranal, E-ELT & Survey Telescopes / Richard Hook / L. Calçada / Leiden Observatory, Leiden University Leiden / Ignas Snellen / Matteo Brogi / Jayne Birkby / Space Research Organization Netherlands (SRON) / Remco de Kok / IAU and Sky & Telescope / Digitized Sky Survey 2 / Videos: ESO / L. Calçada / A. Fujii/Digitized Sky Survey 2. Music: Disasterpeace (http://disasterpeace.com/).

Curiosity Rover on Track for Early August Landing










NASA - Mars Science Laboratory (MSL) patch.

June 27, 2012


Mission Status Report

A maneuver on Tuesday adjusted the flight path of NASA's Mars Science Laboratory spacecraft for delivering the rover Curiosity to a landing target beside a Martian mountain.

The car-size, one-ton rover is bound for arrival the evening of Aug. 5, 2012, PDT (early Aug. 6, EDT and Universal Time). The landing will mark the beginning of a two-year prime mission to investigate whether one of the most intriguing places on Mars ever offered an environment favorable for microbial life.


This artist's concept features NASA's Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars' past or present ability to sustain microbial life. Image credit: NASA / JPL-Caltech.

The latest trajectory correction maneuver, the third and smallest since the Nov. 26, 2011, launch, used four thruster firings totaling just 40 seconds. Spacecraft data and Doppler-effect changes in radio signal from the craft indicate the maneuver succeeded. As designed by engineers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., the maneuver adjusts the location where the spacecraft will enter Mars' atmosphere by about 125 miles (200 kilometers) and advances the time of entry by about 70 seconds.

"This puts us closer to our entry target, so if any further maneuvers are needed, I expect them to be small," said JPL's Tomas Martin-Mur, the mission's navigation team chief. Opportunities for up to three additional trajectory correction maneuvers are scheduled during the final eight days of the flight.

The maneuver served both to correct errors in the flight path that remained after earlier correction maneuvers and to carry out a decision this month to shift the landing target about 4 miles (7 kilometers) closer to the mountain.

It altered the spacecraft's velocity by about one-tenth of a mile per hour (50 millimeters per second). The flight's first and second trajectory correction maneuvers produced velocity changes about 150 times larger on Jan. 11 and about 20 times larger on March 26.

Shifting the landing target closer to the mountain, informally named Mount Sharp, may shave months off the time needed for driving from the touchdown location to selected destinations at exposures of water-related minerals on the slope of the mountain.

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Curiosity's Seven Minutes of Terror

The flight to Mars has entered its "approach phase" leading to landing day. Mission Manager Arthur Amador of JPL said, "In the next 40 days, the flight team will be laser-focused on the preparations for the challenging events of landing day -- continuously tracking the spacecraft's trajectory and monitoring the health and performance of its onboard systems, while using NASA's Deep Space Network to stay in continuous communications. We're in the home stretch now. The spacecraft continues to perform very well. And the flight team is up for the challenge."

Descent from the top of Mars' atmosphere to the surface will employ bold techniques enabling use of a smaller target area and heavier landed payload than were possible for any previous Mars mission. These innovations, if successful, will place a well-equipped mobile laboratory into a locale especially well suited for its mission of discovery. The same innovations advance NASA toward capabilities needed for human missions to Mars.

A video about the challenges of the landing is online at: http://go.nasa.gov/Q4b35n or http://go.usa.gov/vMn .

As of June 27, the Mars Science Laboratory spacecraft carrying the rover Curiosity will have traveled about 307 million miles (494 million kilometers) of its 352-million-mile (567-million-kilometer) flight to Mars.

JPL, a division of the California Institute of Technology in Pasadena, manages the mission for the NASA Science Mission Directorate, Washington. More information about Curiosity is online at http://www.nasa.gov/msl.and http://mars.jpl.nasa.gov/msl/ . You can follow the mission on Facebook at: http://www.facebook.com/marscuriosity and on Twitter at: http://www.twitter.com/marscuriosity

Image (mentioned), Video, Text, Credits: NASA / Jet Propulsion Laboratory / Guy Webster / DC Agle.

Best regards, Orbiter.ch

Exhumed rocks reveal Mars water ran deep












ESA - Mars Express Mission patch.

27 June 2012

By studying rocks blasted out of impact craters, ESA’s Mars Express has found evidence that underground water persisted at depth for prolonged periods during the first billion years of the Red Planet’s existence.

Impact craters are natural windows into the history of planetary surfaces – the deeper the crater, the further back in time you can probe.

In addition, rocks blasted out during the impact offer a chance to study material that once lay hidden beneath the surface.

Excavating water-rich rocks

In a new study, ESA’s Mars Express and NASA’s Mars Reconnaissance Orbiter zoomed in on craters in a 1000 x 2000 km region of the ancient southern highlands, called Tyrrhena Terra, to learn more about the history of water in this region.

Focusing on the chemistry of rocks embedded in the crater walls, rims and central uplifts, as well as the surrounding exhumed material, scientists identified 175 sites bearing minerals formed in the presence of water. 

Mars Express

“The large range of crater sizes studied, from less than 1 km to 84 km wide, indicates that these hydrated silicates were excavated from depths of tens of metres to kilometres,” says Damien Loizeau, lead author of the study.

“The composition of the rocks is such that underground water must have been present here for a long period of time in order to have altered their chemistry.”

While the material excavated by impacts appears to have been in close contact with water, there is little evidence for rocks on the surface lying between the craters in Tyrrhena Terra having been altered by water.

Tyrrhena Terra (Click for enlarge)

“Water circulation occurred several kilometres deep in the crust some 3.7 billion years ago, before the majority of craters formed in this region,” says co-author Nicolas Mangold.

“The water generated a diverse range of chemical changes in the rocks that reflect low temperatures near the surface to high temperatures at depth, but without a direct relationship to the surface conditions at that time.”

By comparison, Mawrth Vallis, one of the largest identified clay-rich regions of Mars, displays a more uniform aqueous mineralogy that indicates a closer link with surface processes.

“The role of liquid water on Mars is of great importance for its habitability and this study using Mars Express describes a very large zone where groundwater was present for a long time,” says Olivier Witasse, ESA’s Mars Express project scientist.

Links:

Mars Express: http://www.esa.int/SPECIALS/Mars_Express/index.html

Mars Express in depth: http://sci.esa.int/science-e/www/area/index.cfm?fareaid=9

Mars Express blog: http://webservices.esa.int/blog/blog/7

Mars Webcam: http://www.esa.int/vmc

Images, Text, Credits: Mars Express HRSC, ESA / DLR / FU Berlin (G. Neukum); NASA / MOLA Science Team; D. Loizeau et al.

Greetings, Orbiter.ch

mardi 26 juin 2012

ISS - Wrapping up six months of work












ESA - PromISSe Mission patch.

26 June 2012

ESA astronaut André Kuipers is scheduled to leave the International Space Station and land on 1 July. André is finishing experiments and packing his bags ready for departure. One of the last experiments is looking at how a human body stays warm.

We take it for granted that our bodies stay at around 37ºC. Go jogging, spend time in a sauna, forget your coat on a cold day and your body will adapt and regulate its temperature. Blood vessels expand or contract and we sweat to keep heat or let excess warmth evaporate.

André Kuipers

On Earth, our bodies rely on convection to cool down: as liquids and gases heat up they become less dense and rise, moving heat away from our skin.

There is no convection in weightlessness so it is surprising that astronauts’ bodies adapt and do not overheat in space. 

The Thermolab project is looking at an astronaut’s temperature during long missions to help understand how our bodies adapt to weightlessness.

As temperature control is particularly important during exercise, scientists on Earth are observing André and his colleagues at rest and during exercise.

Exercise on Station

The experiment is run in conjunction with NASA research on maximum oxygen intake as astronauts on the Station use an exercise bicycle.

Using traditional thermometers in space is time-consuming and impractical. Instead, André has two sensors on his forehead and chest that measure his temperature continuously.

The sensor was first used by ESA astronaut Frank De Winne in 2009 and then extensively during the Mars500 mission to measure how body temperature depends on the night and day cycle.

Thermolab sensor for Mars500

Hospitals are showing an interest in the Thermolab equipment. Being able to monitor body temperature can provide an early warning to a change in a patient’s condition. As the system is non-invasive, it is more hygienic and easier to use.

André and his two crewmates will land at 10:15 GMT (12:15 CEST) on Sunday 1 July. Watch the landing via ESA and read his blog as he enters the last weeks of his PromISSe mission.

Related links:

Science aboard: http://www.esa.int/SPECIALS/PromISSe/SEM1LDJ37SG_0.html

Odissea: http://www.esa.int/odissea

Thermolab factsheet (PDF): http://www.koralewski.de/produkte/healthlab/ThermoLab_TL08%20_si.pdf

Follow André's mission: http://www.esa.int/SPECIALS/PromISSe/SEM2N1WWVUG_0.html

Images, Text, Credits: ESA / NASA / ZWMB, Charité Berlin.

Greetings, Orbiter.ch

A fleeting flyby of a battered world












ESA - Rosetta Mission patch.

26 June 2012

The long and tumultuous history of asteroid Lutetia was revealed by ESA’s Rosetta spacecraft as it raced past this large, ancient asteroid.

This spectacular movie shows a sequence of images snapped by Rosetta as it flew past the main-belt asteroid on 10 July 2010.

video

The sequence begins nine and a half hours before Rosetta made its closest pass, when the asteroid still appeared like a distant tumbling speck seen from a distance of 500 000 km.

Surface features quickly loom into view and the movie concludes six minutes after closest approach, with Rosetta 6300 km from the asteroid.

A wide variety of impact craters and other features that scar the surface of Lutetia, all revealed for the first time, provide a window into the asteroid’s geological past.

Perhaps the most prominent feature is a 57 km-wide crater that marks one of the most dramatic collision events in the asteroid’s long history. Lutetia’s oldest craters are estimated to be 3.4–3.7 billion years old, while the youngest regions are just a few tens of millions of years old.

Rosetta spacecraft

Networks of grooves, fractures and fault lines suggest that seismic events also played a role in shaping the asteroid’s surface.

Lutetia is thought to be a survivor from the very earliest period of Solar System formation some 4.5 billion years ago, and may even have tried to grow a metal heart, just like the planets.

The Rosetta spacecraft is now on its way to rendezvous with comet 67P/Churyumov–Gerasimenko in May 2014. A few months later, its Philae probe will separate to make the first controlled landing on a comet.

Related links:

Rosetta in depth: http://sci.esa.int/rosetta

ESA's comet chaser: http://www.esa.int/SPECIALS/Rosetta/index.html

Rosetta Blog: http://webservices.esa.int/blog/blog/5/

Image, Video, Text, Credits: ESA 2012 MPS for OSIRIS Team MPS / UPD / LAM / IAA / RSSD / INTA / UPM / DASP / IDA.

Best regards, Orbiter.ch

lundi 25 juin 2012

China completes manual space module docking










CNSA - China National Space Agency logo.

June 25, 2012

Three Chinese astronauts have manually docked their spacecraft with an orbiting module, a first for the country as it strives to match US and Russian space exploits.

The Shenzhou 9 capsule completed the manoeuvre with the Tiangong 1 module shortly before 1pm (5am GMT) on Sunday 24 June. The docking – shown live on Chinese TV – follows a docking last week that was controlled remotely from a ground base in China.


Image above: The Tiangong 1 module seen via a camera in the Shenzhou 9 spacecraft before the automatic docking.

The Chinese astronauts have been living and working in the module for the past week as part of preparations for manning a permanent space station. They returned to the Shenzhou 9 capsule early on Sunday and disconnected in preparation for the manual re-connection.

video
Chinese Astronauts Successfully Completed Manual Space Docking

The crew includes 33-year-old Liu Yang, an air force pilot and China's first female space traveller. Liu is joined by mission commander and veteran astronaut Jing Haipeng, 45, and Liu Wang, 43.

Their mission, which is expected to last at least 10 days, is China's fourth manned mission. Shenzhou 9 launched on 16 June from the Jiuquan centre on the edge of the Gobi desert in northern China.

China is hoping to join the US and Russia as the only countries to send independently maintained space stations into orbit. It is already one of just three nations to have launched manned spacecraft on their own.

Artist illustration of the Shenzhou 9 docking with the Tiangong 1

Another manned mission to the module is planned later this year. Possible future missions could include sending a man to the moon.

The Tiangong 1, which was launched last year, is due to be replaced by a permanent space station in around 2020. That station is to weigh about 60 tonnes, slightly smaller than Nasa's Skylab of the 1970s and about one-sixth the size of the 16-nation International Space Station.

For more information about CNSA, visit: http://www.cnsa.gov.cn/n615709/cindex.html

Images, Video, Text, Credits: AFP / CNSA / CCTV.

Best regards, Orbiter.ch

Cassini Shows Why Jet Streams Cross-Cut Saturn








NASA / ESA - Cassini "Insider's" logo.

June 25, 2012

Turbulent jet streams, regions where winds blow faster than in other places, churn east and west across Saturn. Scientists have been trying to understand for years the mechanism that drives these wavy structures in Saturn's atmosphere and the source from which the jets derive their energy.

In a new study appearing in the June edition of the journal Icarus, scientists used images collected over several years by NASA's Cassini spacecraft to discover that the heat from within the planet powers the jet streams. Condensation of water from Saturn's internal heating led to temperature differences in the atmosphere. The temperature differences created eddies, or disturbances that move air back and forth at the same latitude, and those eddies, in turn, accelerated the jet streams like rotating gears driving a conveyor belt.


Image above: A particularly strong jet stream churns through Saturn's northern hemisphere in this false-color view from NASA's Cassini spacecraft. Image credit: NASA/JPL-Caltech/SSI.

A competing theory had assumed that the energy for the temperature differences came from the sun. That is how it works in the Earth's atmosphere.

"We know the atmospheres of planets such as Saturn and Jupiter can get their energy from only two places: the sun or the internal heating. The challenge has been coming up with ways to use the data so that we can tell the difference," said Tony Del Genio of NASA's Goddard Institute for Space Studies, N.Y., the lead author of the paper and a member of the Cassini imaging team.

The new study was possible in part because Cassini has been in orbit around Saturn long enough to obtain the large number of observations required to see subtle patterns emerge from the day-to-day variations in weather. "Understanding what drives the meteorology on Saturn, and in general on gaseous planets, has been one of our cardinal goals since the inception of the Cassini mission," said Carolyn Porco, imaging team lead, based at the Space Science Institute, Boulder, Colo. "It is very gratifying to see that we're finally coming to understand those atmospheric processes that make Earth similar to, and also different from, other planets."

Rather than having a thin atmosphere and solid-and-liquid surface like Earth, Saturn is a gas giant whose deep atmosphere is layered with multiple cloud decks at high altitudes. A series of jet streams slice across the face of Saturn visible to the human eye and also at altitudes detectable to the near-infrared filters of Cassini's cameras. While most blow eastward, some blow westward. Jet streams occur on Saturn in places where the temperature varies significantly from one latitude to another.

Thanks to the filters on Cassini's cameras, which can see near-infrared light reflected to space, scientists now have observed the Saturn jet stream process for the first time at two different, low altitudes. One filtered view shows the upper part of the troposphere, a high layer of the atmosphere where Cassini sees thick, high-altitude hazes and where heating by the sun is strong. Views through another filter capture images deeper down, at the tops of ammonia ice clouds, where solar heating is weak but closer to where weather originates. This is where water condenses and makes clouds and rain.

In the new study, which is a follow-up to results published in 2007, the authors used automated cloud tracking software to analyze the movements and speeds of clouds seen in hundreds of Cassini images from 2005 through 2012.

"With our improved tracking algorithm, we've been able to extract nearly 120,000 wind vectors from 560 images, giving us an unprecedented picture of Saturn's wind flow at two independent altitudes on a global scale," said co-author and imaging team associate John Barbara, also at the Goddard Institute for Space Studies. The team's findings provide an observational test for existing models that scientists use to study the mechanisms that power the jet streams.


This figure (above) examines a particularly strong jet stream and the eddies that drive it through the atmosphere of Saturn's northern hemisphere. Image credit: NASA/JPL-Caltech/SSI.

By seeing for the first time how these eddies accelerate the jet streams at two different altitudes, scientists found the eddies were weak at the higher altitudes where previous researchers had found that most of the sun's heating occurs. The eddies were stronger deeper in the atmosphere. Thus, the authors could discount heating from the sun and infer instead that the internal heat of the planet is ultimately driving the acceleration of the jet streams, not the sun. The mechanism that best matched the observations would involve internal heat from the planet stirring up water vapor from Saturn's interior. That water vapor condenses in some places as air rises and releases heat as it makes clouds and rain. This heat provides the energy to create the eddies that drive the jet streams.

The condensation of water was not actually observed; most of that process occurs at lower altitudes not visible to Cassini. But the condensation in mid-latitude storms does happen on both Saturn and Earth. Storms on Earth – the low- and high-pressure centers on weather maps – are driven mainly by the sun's heating and do not mainly occur because of the condensation of water, Del Genio said. On Saturn, the condensation heating is the main driver of the storms, and the sun's heating is not important.

Images of one of the strongest jet streams and a figure from the paper can be found at http://www.nasa.gov/cassini , http://saturn.jpl.nasa.gov and http://ciclops.org .

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute in Boulder, Colo.

Images (mentioned), Credits: NASA's Goddard Space Flight Center / Bill Steigerwald / Nancy Neal Jones / Space Science Institute / Joe Mason / JPL / Jia-Rui C. Cook.

Greetings, Orbiter.ch