vendredi 5 juillet 2013

Phobos Passing Overhead












NASA - Mars Science Laboratory (MSL) patch.

July 5, 2013

video

This movie clip shows Phobos, the larger of the two moons of Mars, passing overhead, as observed by NASA's Mars rover Curiosity in a series of images centered straight overhead starting shortly after sunset.  Phobos first appears near the lower center of the view and moves toward the top of the view.  The clip runs at accelerated speed; the amount of time covered in it is about 27 minutes.

The 86 frames combined into this clip were taken by the rover's Navigation Camera (Navcam) on the 317th Martian day of Curiosity's work on Mars (June 28, 2013, PDT).  The apparent ring about halfway between the center of the frames and the edges is an artifact of the imaging due to scattering of light inside the camera.

For more about NASA's Curiosity mission, visit: http://www.nasa.gov/mars and http://marsprogram.jpl.nasa.gov/msl

Follow the mission on Facebook and Twitter at: http://www.facebook.com/marscuriosity and http://www.twitter.com/marscuriosity

Video, Text, Credits: NASA / JPL-Caltech.

Greetings, Orbiter.ch

jeudi 4 juillet 2013

Feeding Galaxy Caught in Distant Searchlight












ESO - European Southern Observatory logo.

4 July 2013

ESO’s Very Large Telescope probes growth of galaxies

Artist’s impression of a galaxy accreting material from its surroundings

Astronomers using ESO’s Very Large Telescope have spotted a distant galaxy hungrily snacking on nearby gas. Gas is seen to fall inwards towards the galaxy, creating a flow that both fuels star formation and drives the galaxy’s rotation. This is the best direct observational evidence so far supporting the theory that galaxies pull in and devour nearby material in order to grow and form stars. The results will appear in the 5 July 2013 issue of the journal Science.

Astronomers have always suspected that galaxies grow by pulling in material from their surroundings, but this process has proved very difficult to observe directly. Now ESO’s Very Large Telescope has been used to study a very rare alignment between a distant galaxy [1] and an even more distant quasar — the extremely bright centre of a galaxy powered by a supermassive black hole. The light from the quasar passes through the material around the foreground galaxy before reaching Earth, making it possible to explore in detail the properties of the gas around the galaxy [2]. These new results give the best view so far of a galaxy in the act of feeding.

“This kind of alignment is very rare and it has allowed us to make unique observations,” explains Nicolas Bouché of the Research Institute in Astrophysics and Planetology (IRAP) in Toulouse, France, lead author of the new paper. “We were able to use ESO’s Very Large Telescope to peer at both the galaxy itself and its surrounding gas. This meant we could attack an important problem in galaxy formation: how do galaxies grow and feed star formation?”

Galaxies quickly deplete their reservoirs of gas as they create new stars, and so must somehow be continuously replenished with fresh gas to keep going. Astronomers suspected that the answer to this problem lay in the collection of cool gas from the surroundings by the gravitational pull of the galaxy. In this scenario, a galaxy drags gas inwards, which then circles around the galaxy, rotating with it before falling in. Although some evidence of such accretion had been observed in galaxies before, the motion of the gas and its other properties had not been fully explored up to now.

The sky around the quasar QSO J2246-6015

The astronomers used two instruments known as SINFONI and UVES [3], both of which are mounted on ESO’s VLT at the Paranal Observatory in northern Chile. The new observations showed both how the galaxy itself was rotating, and revealed the composition and motion of the gas outside the galaxy.

“The properties of this vast volume of surrounding gas were exactly what we would expect to find if the cold gas was being pulled in by the galaxy,” says co-author Michael Murphy (Swinburne University of Technology, Melbourne, Australia). “The gas is moving as expected, there is about the expected amount and it also has the right composition to fit the models perfectly. It’s like feeding time for lions at the zoo — this particular galaxy has a voracious appetite, and we’ve discovered how it feeds itself to grow so quickly.”

Astronomers have already found evidence of material around galaxies in the early Universe, but this is the first time that they have been able to show clearly that the material is moving inwards rather than outwards, and also to determine the composition of this fresh fuel for future generations of stars. Without the quasar’s light to act as a probe this surrounding gas would be undetectable.

“In this case we were lucky that the quasar happened to be in just the right place for its light to pass through the infalling gas. The next generation of extremely large telescopes will enable studies with multiple sightlines per galaxy and provide a much more complete view,” concludes co-author Crystal Martin (University of California Santa Barbara, USA).

Notes:

[1] This galaxy was detected in the 2012 redshift z ~ 2 SINFONI survey called the SINFONI Mg II Program for Line Emitters (SIMPLE). The quasar in the background is called QSO J2246-6015, or HE 2243-60 and the galaxy itself lies at a redshift of 2.3285 — meaning that we are seeing it when the Universe was just about two billion years old.

[2] When the quasar light passes through the gas clouds some wavelengths are absorbed. The patterns of these absorption fingerprints can tell astronomers much about the motions and chemical composition of the gas. Without the quasar in the background far less information would have been be obtained — the gas clouds do not shine and are not visible in direct images.

[3] SINFONI is the Spectrograph for INtegral Field Observations in the Near Infrared, while UVES is the Ultraviolet and Visual Echelle Spectrograph. Both are mounted on ESO’s Very Large Telescope. SINFONI revealed the motions of the gas in the galaxy itself and UVES the effects of the gas around the galaxy on the light coming from the more distant quasar.

More information:

This research was presented in a paper entitled “Signatures of Cool Gas Fueling a Star-Forming Galaxy at Redshift 2.3”, to appear in the 5 July 2013 issue of the journal Science.

The team is composed of N. Bouché (CNRS; IRAP, France), M. T. Murphy (Swinburne University of Technology, Melbourne, Australia), G. G. Kacprzak (Swinburne University of Technology, Australia; Australian Research Council Super Science Fellow), C. Péroux (Aix Marseille University, CNRS, France), T. Contini (CNRS; University Paul Sabatier of Toulouse, France), C. L. Martin (University of California Santa Barbara, USA), M. Dessauges-Zavadsky (Observatory of Geneva, Switzerland).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. 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 the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links:

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

Images, Text, Credits: ESO / L. Calçada / ESA / AOES Medialab / Digitized Sky Survey 2. Acknowledgement: Davide De Martin.

Greetings, Orbiter.ch

At the foot of the Red Planet’s giant volcano












ESA - Mars Express Mission patch.

4 July 2013

 Olympus Mons southeast flank

Hundreds of individual lava flows are seen frozen in time on the flanks of Olympus Mons, the largest volcano in the Solar System.

The images, taken on 21 January 2013 by ESA’s Mars Express, focus on the southeast segment of the giant volcano, which towers some 22 km above the surrounding plains. This is more than double the height of Mauna Kea, the tallest volcano on Earth at 10 km, when measured from its oceanic base to summit.

Olympus Mons in context

Like Mauna Kea, Olympus Mons is a shield volcano, with gently sloping sides that extend outwards at low angles. But unlike other shield volcanoes, it has an abrupt cliff edge, or scarp, separating it from the surrounding plains.

The scarp circles the entire volcano, in places reaching 9 km high. It was likely formed during a number of catastrophic landslides on the flanks of the volcano, during which the resulting debris was transported several hundred kilometres beyond the extent of these images.

Lava flows cover the base of the volcano, punctuated by a handful of pointy and flat-topped blocks that were either rotated or uplifted during the collapse.

Olympus Mons flank topography

The transition from the towering heights of the volcano down onto the flat lava plain at the base of the scarp can be easily seen in the colour-coded topography image.

In the leading colour image and perspective views, extensive networks of narrow, overlapping lava flows are proof of an extremely active volcanic past. The lava, long since solidified, once spilled down the natural contours of the volcano, spreading out into broad fans as it reached the scarp and plains below.

Flows that ended before reaching the scarp did so with rounded tongues, as the lava cooled and crept to a stop.

Perspective view of Olympus Mons flanks

Some lava flows are bounded by steep channel walls, while others were contained in lava tubes. Zooming in to the top left portion of the flank in the leading image reveals one example of an ancient lava tube, its winding track partially exposed in channel segments where the roof of the tunnel has since collapsed.

Perspective view of Olympus Mons flanks

The chaotic lava flows on the flanks provide a stark contrast to the smooth plains seen surrounding the volcano.

Here, only two prominent features are visible: a ‘wrinkle ridge’ in the lower centre of the main image, which formed as lava cooled and contracted to buckle up and distort the surface, and a channel system that branches out into a horseshoe shape. This channel was likely carved by lava, but water may have once flowed here, too.

The flank of Olympus Mons in 3D

The occurrence of only a few small impact craters in this scene shows that it is relatively young compared with more heavily cratered regions elsewhere on Mars – the older the surface, the greater the exposure time to impact events by asteroids or comets.

Furthermore, by looking at how the lava flows overlap, one can determine their relative ages: those that lie on top, cutting through and overprinting other flows, are the youngest.

For example, the vast lava plain surrounding the volcano truncates the majority of lava flows extending from the flanks, suggesting it is younger still, and that it originated from a location outside of this scene.

The volcanic region hosting Olympus Mons and several other large volcanoes is thought to have been active until tens of millions of years ago, relatively recent on the planet’s geological timescale that spans 4.6 billion years.

Related links:

Mars Express overview: http://www.esa.int/Our_Activities/Space_Science/Mars_Express_overview

Mars Express 10 year brochure: http://esamultimedia.esa.int/multimedia/publications/BR-312/

High Resolution Stereo Camera: http://berlinadmin.dlr.de/Missions/express/indexeng.shtml

Behind the lens: http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Behind_the_lens

Frequently asked questions: http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Frequently_asked_questions

ESA Planetary Science archive (PSA): http://www.rssd.esa.int/PSA

NASA Planetary Data System: http://pds-geosciences.wustl.edu/missions/mars_express/hrsc.htm

HRSC data viewer: http://hrscview.fu-berlin.de/

Images, Text, Credits: ESA / DLR / FU Berlin (G. Neukum) / NASA MGS MOLA Science Team.

Best regards, Orbiter.ch

mercredi 3 juillet 2013

Spacecraft Resource-P issued the first test shots










ROSCOSMOS patch.

03.07.2013

 Artist's view of Resource-P satellite in orbit

July 2, 2013 conducted the first test include electro-optical target surveillance equipment (Geoton) installed on the spacecraft (SC) Resource-P, have been surveyed, and the first images of the Earth. According to preliminary estimates of experts, is currently performing the processing and analysis of the information received, the resulting images are broadly consistent with the specified requirements and confirm the high performance characteristics of the spacecraft.

Launching of the remote sensing of the Earth Resource-P was successfully implemented June 25, 2013 from the Baikonur Cosmodrome launch vehicle Soyuz-2.1b. Since then, the check is made on-board systems of the spacecraft. Parameters for the spacecraft (temperature, pressure in the compartments, the supply voltage) are in the normal range. Comments on the work of the on-board equipment is not.

Flight testing of the spacecraft Resource-P progress:

 One of the first images obtained from satellite Resource-P. 02.07.2013

 Another of the first images obtained from satellite Resource-P. 02.07.2013

Spacecraft Resource-P created SRP TsSKB Progress on the basis of the existing backlog and project developments to improve its performance targets in the following key areas: increasing the number of narrow spectral ranges from 3 to 5, providing hyperspectral and stereo, snap pictures with the provision of accuracy of 10-15 meters, an increase of lifetime spacecraft with 3 to 5 years.

Space complex Resource-P is for high-precision, detailed broadband and hyperspectral optical-electronic monitoring Earth's surface. This spacecraft was the second in a series of satellites of the "resource" in the domestic constellation of civilian remote sensing of the Earth c detailed level permissions.

Resource-P (Resurs-P) is intended to inform the following applications of Earth observation:

- Compiling and updating the general geographic, thematic and topographic maps;

- Control of pollution and environmental degradation;

- Inventory of natural resources and monitor business processes to ensure the rational activity in various sectors of the economy;

- Information management activities for oil exploration, natural gas, ore and other mineral deposits;

- Control of development of territories, to obtain data for engineering evaluation areas for the benefit of economic activity;

- Control of water conservation and protected areas;

- Assess ice conditions;

- Observation of emergencies, disasters, accidents, man-made disasters, as well as assess their implications for planning remediation.

The information obtained can also be used to promote international cooperation in the Russian part of the global Earth observations and solutions of other pressing problems of remote sensing of the Earth.

Other of the first images obtained from satellite Resource-P. 02.07.2013

Resource-P - a device with a qualitatively new features, including the use on it a special target equipment. One of the basic principles of formation of shape space complex (CC) Resource-P is the use of technical solutions which have been accumulated in creating QC Resource-DK. Were retained capabilities of the spacecraft Resource-DK in width of the capture and the level of resolution in panchromatic and spectral ranges. It operates at near-circular sun-synchronous orbit, which can significantly improve the observations on the Resurs-DK, working on an elliptical orbit. The new spacecraft will be able to shoot at the same height and in the same lighting conditions. The frequency of observation is reduced from six to three days. Furthermore, improved consumer properties and precision reference images transmitted to Earth dynamic characteristics of the spacecraft.

Capacity of tactical and technical characteristics of the new spacecraft achieved through the use of several types of imaging equipment. At the Resource-P is set opto-electronic equipment, which will deliver highly detailed images with a resolution of 1 m with a height of 475 km in the panchromatic band, a narrow spectral bands with a resolution of at least 4.3 meters.

 Resource-P description (in Russian)

The task of equipment Resource-P introduced two other types of imaging equipment: hyperspectral survey equipment - GSA (development of CMH) and a set of wide field multispectral imaging equipment - KSHMSA (development branch SRP TsSKB Progress - SPE OPTEKS ). Locking band hyperspectral instrument is 25 km and a resolution of about 25 m KSHMSA allows detailed observation with wide with a resolution of 12 m swath of 100 km, with a resolution of 60 m - a swath width of 440 km. Together with panchromatic images allows simultaneous recording at fixed spectral ranges.

The presence of this equipment will increase list and quality of the spacecraft solved problems in the socio-economic development of the country and its regions.

ROSCOSMOS Press Release: http://www.federalspace.ru/main.php?id=2&nid=20195

Images, Text, Credits: Press Service of the Russian Federal Space Agency (Roscosmos PAO) / ROSCOSMOS / Translation: Orbiter.ch Aerospace.

Greetings, Orbiter.ch

Anniversary of the Mars Pathfinder Landing









NASA - Mars Pathfinder Mission patch.

July 3, 2013


Mars Pathfinder was launched on Dec. 4, 1996 at 1:58:07 am EST on a Delta II rocket. After an uneventful journey, the spacecraft safely landed on the surface of Mars on July 4, 1997. The first set of data was received shortly after 5:00 p.m. followed by the release of images at 9:30 p.m. The Sojourner rover, with three Lewis components, then began its Martian trek and returned images and other data over the course of three months. After operating on the surface of Mars three times longer than expected and returning a tremendous amount of new information about the red planet, NASA's Mars Pathfinder mission completed the last successful data transmission cycle from Pathfinder at 6:23 a.m. EDT on Sept. 27, 1997.

A panoramic view of Pathfinder's Ares Vallis landing site reveals traces of a warmer, wetter past, showing a floodplain covered with a variety of rock types, boulders, rounded and semi-rounded cobbles and pebbles. These rocks and pebbles are thought to have been swept down and deposited by floods which occurred early in Mars' evolution in the Ares and Tiu regions near the Pathfinder landing site.

The image, which is a 75-frame, color-enhanced mosaic taken by the Imager for Mars Pathfinder, looks to the southwest toward the Rock Garden, a cluster of large, angular rocks tilted in a downstream direction from the floods. The Pathfinder rover, Sojourner, is shown snuggled against a rock nicknamed Moe. The south peak of two hills, known as Twin Peaks, can be seen on the horizon, about 1 kilometer (6/10ths of a mile) from the lander. The rocky surface is comprised of materials washed down from the highlands and deposited in this ancient outflow channel by a catastrophic flood.


Image above: Artist's view of the Mars Pathfinder arrived at the red planet on July 4, 1997.Image credit: NASA / JPL.

The remarkably successful Mars Pathfinder spacecraft, part of NASA's Discovery program of fast track, low-cost missions with highly focused science objectives, was the first spacecraft to explore Mars in more than 20 years. In all, during its three months of operations, the mission returned about 2.6 gigabits of data, which included more than 16,000 images of the Martian landscape from the lander camera, 550 images from the rover and about 8.5 million temperature, pressure and wind measurements.

For more information about Mars Pathfinder Mission, visit: http://www.nasa.gov/mission_pages/mars-pathfinder/ and http://mars.jpl.nasa.gov/MPF/

Images, Text, Credits: NASA / JPL.

Cheers, Orbiter.ch

Long-Running NASA / CNES Ocean Satellite Takes Final Bow











NASA / CNES - Jason-1 Ocean satellite patch.

July 3, 2013


Image above: Artist's concept of the joint NASA/CNES Jason-1 ocean altimetry satellite. During its 11-1/2-year life, Jason-1 helped create a 20-plus-year climate record of global ocean surface topography, providing new insights into ocean circulation, tracking our rising seas and enabling more accurate weather, ocean and climate forecasts. Image Credit: NASA/JPL-Caltech.

The curtain has come down on a superstar of the satellite oceanography world that played the "Great Blue Way" of the world's ocean for 11-1/2 years. The successful joint NASA and Centre National d'Etudes Spatiales (CNES) Jason-1 ocean altimetry satellite was decommissioned this week following the loss of its last remaining transmitter.

Launched Dec. 7, 2001, and designed to last three to five years, Jason-1 helped create a revolutionary 20-plus-year climate data record of global ocean surface topography that began in 1992 with the launch of the NASA/CNES Topex/Poseidon satellite. For more than 53,500 orbits of our planet, Jason-1 precisely mapped sea level, wind speed and wave height for more than 95 percent of Earth's ice-free ocean every 10 days. The mission provided new insights into ocean circulation, tracked our rising seas and enabled more accurate weather, ocean and climate forecasts. 

"Jason-1 has been a resounding scientific, technical and international success," said John Grunsfeld, associate administrator of NASA's Science Mission Directorate in Washington. "The mission met all of its requirements, performed an extended mission and demonstrated how a long-term climate data record should be established from successively launched satellites. Since launch, it has charted nearly 1.6 inches (4 centimeters) of rise in global sea levels, a critical measure of climate change and a direct result of global warming. The Jason satellite series provides the most accurate measure of this impact, which is felt all over the globe."


Graphic above: Jason-1 contributed to this 20-year data record of the global mean sea level change, providing the first direct measurement of this important indicator of global climate change.
Image Credit: University of Colorado.

During parts of its mission, Jason-1 flew in carefully coordinated orbits with both its predecessor Topex/Poseidon and its successor, the Ocean Surface Topography Mission/Jason-2, launched in 2008. These coordinated orbit periods, which lasted about three years each, cross-calibrated the satellites, making possible a 20-plus-year unbroken climate record of sea level change. These coordination periods also doubled data coverage.

Combined with data from the European Space Agency's Envisat mission, which also measured sea level from space, these data allow scientists to study smaller-scale ocean circulation phenomena, such as coastal tides, ocean eddies, currents and fronts. These small-scale features are thought to be responsible for transporting and mixing heat and other properties, such as nutrients and dissolved carbon dioxide, within the ocean.

"Jason-1 was an exemplary and multi-faceted altimeter mission and contributed so much to so many scientific disciplines," said Jean-Yves Le Gall, CNES president in Paris. "Not only did Jason-1 extend the precise climate record established by Topex/Poseidon, it made invaluable observations for mesoscale ocean studies on its second, interleaved orbit. Even from its 'graveyard' orbit, Jason-1 continued to make unprecedented new observations of the Earth's gravity field, with precise measurements right till the end."

The in-orbit Jason-2 mission, operated by the meteorological agencies of the United States and Europe (the National Oceanic and Atmospheric Administration and EUMETSAT, respectively) in collaboration with NASA and CNES, is in good health and continues to collect science and operational data. This same U.S./European team is preparing to launch the next satellite in the series, Jason-3, in March 2015. 


Image above: Regional changes in sea level based on the 19-year trend from 1993 through 2012, as measured using radar altimeter data from several satellites, including the NASA/CNES Jason-1 mission. Reds and purples represent the largest increases in sea level, with blues representing the largest decreases. These changes reflect the impact of decadal-scale climate variability on the regional distribution of sea level rise. Image Credit: University of Colorado.

Contact was lost with the Jason-1 satellite on June 21 when it was out of visibility of ground stations. At the time of the last contact, Jason-1 and its instruments were healthy, with no indications of any alarms or anomalies. Subsequent attempts to re-establish spacecraft communications from U.S. and French ground stations were unsuccessful. Extensive engineering operations undertaken to recover downlink communications also were unsuccessful.

After consultation with the spacecraft and transmitter manufacturers, it was determined a non-recoverable failure with the last remaining transmitter on Jason-1 was the cause of the loss of contact. The spacecraft's other transmitter experienced a permanent failure in September 2005. There now is no remaining capability to retrieve data from the Jason-1 spacecraft. 

On July 1, mission controllers commanded Jason-1 into a safe hold state that reinitialized the satellite. After making several more unsuccessful attempts to locate a signal, mission managers at CNES and NASA decided to proceed with decommissioning Jason-1.  The satellite was then commanded to turn off its magnetometer and reaction wheels. Without these attitude control systems, Jason-1 and its solar panels will slowly drift away from pointing at the sun and its batteries will discharge, leaving it totally inert within the next 90 days. The spacecraft will not reenter Earth's atmosphere for at least 1,000 years.

"Like its predecessor Topex/Poseidon, Jason-1 provided one of the most comprehensive pictures of changes in the tropical Pacific Ocean, including the comings and goings of El Nino and La Nina events," said Lee-Lueng Fu, Jason-1 project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "These Pacific Ocean climate cycles are responsible for major shifts in sea level, ocean temperatures and rainfall every two to five years and can sometimes be so large that worldwide weather patterns are affected. Jason-1 data have been instrumental in monitoring and predicting these ever-changing cycles."

In the spring of 2012, based on concern over the limited redundancy of Jason-1's aging control systems, NASA and CNES moved the satellite into its planned final "graveyard" orbit, depleted its extra fuel and reconfigured the mission to make observations that will improve our knowledge of Earth's gravity field over the ocean, in addition to delivering its oceanographic data products.

The first full 406-day marine gravity mission was completed on June 17. The resulting data have already led to the discovery of numerous small seamounts, which are underwater mountains that rise above the deep-sea floor. The data also have significantly increased the resolution of Earth's gravity field over the ocean, while increasing our knowledge of ocean bathymetry, which is the underwater depth of the ocean floor.

JPL manages the U.S. portion of the Jason-1 mission for NASA's Science Mission Directorate. CNES manages the French portion of the mission.

For more information on Jason-1, visit: http://sealevel.jpl.nasa.gov and http://www.aviso.oceanobs.com .

The California Institute of Technology in Pasadena manages JPL for NASA.

Images (mentioned), Text, Credits: NASA / Steve Cole / JPL / Alan Buis / Centre National d'Etudes Spatiales, Paris, France / Julien Watelet.

Best regards, Orbiter.ch

Mars Rover Opportunity Passes Half-Way Point to Next Destination

NASA - Mars Exploration Rover B "Opportunity" (MER-B) patch.

July 3, 2013

NASA's Mars Exploration Rover Opportunity has driven more than half of the distance needed to get from a site where it spent 22 months to its next destination.

The rover has less than half a mile (800 meters) to go to finish a 1.2-mile (2-kilometer) dash from one crater-rim segment, where it worked since mid-2011, to another, where mission controllers intend to keep Opportunity busy during the upcoming Martian winter.

Opportunity departed the southern tip of the "Cape York" segment six weeks ago and headed south for "Solander Point." Both are raised portions of the western rim of 14-mile-wide (22-kilometer-wide) Endeavour Crater, offering access to older geological deposits than the rover visited during its first seven years on Mars. Opportunity was launched from Florida on July 7, 2003, EDT (July 8, UTC). It landed on Mars Jan. 24, 2004, PDT (Jan. 25, EDT and UTC).


Image above: This view shows the terrain that NASA's Mars Exploration Rover Opportunity is crossing in a flat area called "Botany Bay" on the way toward "Solander Point," which is visible on the horizon. Image Credit: NASA/JPL-Caltech.

A flatter area called Botany Bay separates Cape York from Solander Point.

"We are making very good progress crossing 'Botany Bay,'" said John Callas of NASA's Jet Propulsion Laboratory, Pasadena, Calif., who is project manager for the nearly decade-old mission.

The terrain is favorable for the trek.

"The surface that Opportunity is driving across in Botany Bay is polygonally fractured outcrop that is remarkably good for driving," said Brad Joliff, an Opportunity science team member and long-term planner at Washington University in St. Louis. "The plates of outcrop, like a tiled mosaic pavement, have a thin covering of soil, not enough to form the wind-blown ripples we've had to deal with during some other long treks. The outcrop plates are light-toned, and the cracks between them are filled with dark, basaltic soil and our old friends the 'blueberries.'"

The BB-size spherules nicknamed "blueberries" are hematite-rich, erosion-resistant concretions that Opportunity discovered at its landing site and continued seeing on much of the ground between there and Endeavour Crater.

Mars Exploration Rover B "Opportunity" (MER-B). Image Credit: NASA/JPL-Caltech

The rise of Solander Point to the south gives the team a very visible destination during the drive. That destination offers both a tall cross section of rock layers for examination and also an expanse of terrain that includes a north-facing slope, which is favorable for the solar-powered rover to stay active and mobile through the coming Martian southern-hemisphere winter.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover Project for NASA's Science Mission Directorate. For more about Spirit and Opportunity, visit http://www.nasa.gov/rovers and http://marsrovers.jpl.nasa.gov . You can follow the project on Twitter and on Facebook at: http://twitter.com/MarsRovers and http://www.facebook.com/mars.rovers .

Images (mentioned), Text, Credits: NASA / JPL / Guy Webster.

Greetings, Orbiter.ch

mardi 2 juillet 2013

Comet ISON Brings Holiday Fireworks











NASA - Hubble Space Telescope patch.

July 2, 2013

This July Fourth the solar system is showing off some fireworks of its own.

Superficially resembling a skyrocket, comet ISON is hurtling toward the sun presently at a whopping 48,000 mph.

video
Hubble View of Comet ISON

Video above: Hubble View of Comet ISON. Video Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA).

Its swift motion is captured in this time-lapse movie made from a sequence of pictures taken May 8, 2013, by NASA’s Hubble Space Telescope. At the time the images were taken, the comet was 403 million miles from Earth, between the orbits of Mars and Jupiter.

The movie shows a sequence of Hubble observations taken over a 43-minute span and compresses this into just five seconds. The comet travels 34,000 miles in this brief video, or 7 percent of the distance between Earth and the moon. The deep-space visitor streaks silently against the background stars.

Unlike a firework, the comet is not combusting, but in fact is pretty cold. Its skyrocket-looking tail is really a streamer of gas and dust bleeding off the icy nucleus, which is surrounded by a bright star-like-looking coma. The pressure of the solar wind sweeps the material into a tail, like a breeze blowing a windsock.

As the comet warms as it moves closer to the sun, its rate of sublimation (a process similar to evaporation in which solid matter transitions directly into gas) will increase. The comet will get brighter and its tail will grow longer. The comet is predicted to reach naked-eye visibility in November.

The comet is named after the organization that discovered it, the Russia-based International Scientific Optical Network.


Image above: This false-color, visible-light image was taken with Hubble’s Wide Field Camera 3. Image Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA).

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

Related Links:
NASA's Asteroids and Comet Watch website: http://www.nasa.gov/mission_pages/asteroids/main/index.html

More on this image from the Space Telescope Science Institute: 1 / 2: http://hubblesite.org/news/2013/24 and http://heritage.stsci.edu/2013/24

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

For more information about NASA / ESA Hubble Space Telescope: http://www.nasa.gov/hubble and http://www.spacetelescope.org/

Image (mentioned), Video (mentioned), Text, Credits: ESA / Space Telescope Science Institute / Ray Villard / Zolt Levay.

Best regards, Orbiter.ch

Inseparable Galactic Twins












ESA - Hubble Space Telescope patch.

July 2, 2013


Image above: The galaxy pair MRK 1034. Image Credit: ESA/Hubble and NASA (acknowledgement, Judy Schmidt).

Looking towards the constellation of Triangulum (The Triangle), in the northern sky, lies the galaxy pair MRK 1034. The two very similar galaxies, named PGC 9074 and PGC 9071, are close enough to one another to be bound together by gravity, although no gravitational disturbance can yet be seen in the image. These objects are probably only just beginning to interact gravitationally.

Both are spiral galaxies, and are presented to our eyes face-on, so we are able to appreciate their distinctive shapes. On the left of the image, spiral galaxy PGC 9074 shows a bright bulge and two spiral arms tightly wound around the nucleus, features which have led scientists to classify it as a type Sa galaxy. Close by, PGC 9071 — a type Sb galaxy — although very similar and almost the same size as its neighbor, has a fainter bulge and a slightly different structure to its arms: their coils are further apart.

The spiral arms of both objects clearly show dark patches of dust obscuring the light of the stars lying behind, mixed with bright blue clusters of hot, recently-formed stars. Older, cooler stars can be found in the glowing, compact yellowish bulge towards the center of the galaxy. The whole structure of each galaxy is surrounded by a much fainter round halo of old stars, some residing in globular clusters.

Gradually, these two neighbors will attract each other, the process of star formation will be increased and tidal forces will throw out long tails of stars and gas. Eventually, after maybe hundreds of millions of years, the structures of the interacting galaxies will merge together into a new, larger galaxy.

The images combined to create this picture were captured by Hubble's Advanced Camera for Surveys.

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

For more information about NASA / ESA Hubble Space Telescope: http://www.nasa.gov/hubble and http://www.spacetelescope.org/

Image (mentioned), Text, Credits: ESA / NASA.

Cheers, Orbiter.ch

Cluster discovers steady leak in Earth's plasmasphere‏












ESA - Cluster II Mission patch.

02 July 2013

A steady wind, discovered by ESA's Cluster mission, is slowly escaping from Earth's plasmasphere - the torus of plasma that surrounds our planet's atmosphere. The outflow amounts to almost 90 tonnes a day. Predicted by theory two decades ago, this is one of the main mechanisms that replenishes Earth's magnetosphere with fresh plasma.

The environment that surrounds Earth, beyond the outermost layers of the atmosphere, is strongly shaped by the magnetic field of our planet. There, space is filled with electrons and positive ions, which move along the magnetic field lines. The interaction between Earth's magnetic field and the solar wind produces the complex topography of the magnetosphere.

The innermost part of the magnetosphere is a doughnut-shaped region called the plasmasphere, which is centred around the Earth's equator and rotates along with it. This plasmasphere, whose toroidal shape is forged by the magnetic field of Earth, exchanges mass and energy with the outer layers of the magnetosphere, and scientists have been studying the details of the interaction between these two regions.

video
Animation of the plasmaspheric wind. Credit: ESA/ATG medialab

"We have long known that the plasmasphere supplies material to the outer magnetosphere," explains Iannis Dandouras from the Institut de Recherche en Astrophysique et Planétologie (a joint CNRS and Université Paul Sabatier institute) in Toulouse, France.

"However, up until now we could only see this happening during sporadic, localised and powerful events that we call plumes."

Analysing data from ESA's Cluster mission, Dandouras has discovered another source of the supply: a steady wind that continuously transfers material from the plasmasphere into the magnetosphere. The results of his study are published in Annales Geophysicae.

"Now we have finally found proof of a permanent and continuous leakage of material from the plasmasphere outwards," he says.

"It is something similar to what happens also around the Sun, when the solar corona expands outwards at equatorial latitudes and gives rise to the solar wind."

Earth's magnetosphere. Credit: ESA/ATG medialab

Scientists had suspected that such a plasmaspheric wind must exist ever since the first observations of plume events in the early 1990s. Plumes are dense columns of plasma that form in the plasmasphere when it is hit by a geomagnetic storm – a disturbance in Earth's magnetic environment caused by sudden changes in the solar wind. After they form, plumes expand outwards and eventually burst, releasing large amounts of fresh plasma in the outer layers of the magnetosphere.

"When a plume strikes out, it partially drains the plasmasphere, which is then replenished with plasma coming from Earth's ionosphere, the top layer of the atmosphere," explains Dandouras.

Early studies of plumes monitored how long it took to refill the plasmasphere after such an event.

"Surprisingly, this process took much longer than expected, like trying to fill up a leaky container."

In 1992 two scientists approached the problem from a theoretical point of view. When Joseph Lemaire, from the Belgian Institute for Space Aeronomy in Brussels, Belgium, was visiting Robert Schunk at Utah State University, USA, they tried to simulate this puzzling finding by investigating the interplay of forces in the plasmasphere. Their study revealed a net imbalance between three players: the gravitational attraction due to Earth's mass, the centrifugal force caused by its rotation and the pressure exerted by the plasma. As a result of the imbalance, an instability develops, driving the plasma outwards.

The plasmasphere in Earth's magnetosphere. Credit: ESA/ATG medialab

The instability predicted by the work of Lemaire and Schunk is continuous rather than episodic, and takes the form of a wind of plasma. The wind is continuously flowing radially out of the doughnut-shaped plasmasphere and into the surrounding layers of the magnetosphere.

It was Lemaire who first introduced Dandouras to this particular problem.

"We were chatting about the plasmasphere at a workshop a few years ago, when Joseph Lemaire mentioned his and Schunk's prediction of this wind," remembers Dandouras.

"Quite some time had passed after their work had been published, yet only indirect evidence was found to support their prediction. As an experimental space scientist, this triggered my curiosity immediately.

"The Cluster mission was already operating and collecting data at the time, and we both agreed that the Cluster Ion Spectrometry experiment (CIS) would be the perfect tool to verify directly whether the plasmasphere is actually leaking."

The plasmaspheric wind is expected to be blowing at all times, regardless of the activity of the magnetosphere; in contrast, plumes only arise when Earth's magnetic environment is highly active. So Dandouras dug into the Cluster archive looking for data that had been gathered during quiet magnetospheric times.

"The inquiry was a very delicate process: if at all present, this wind would be very weak, and it would be really challenging to single it out from the overall distribution of the low-energy ions that make up the plasmasphere," says Dandouras.

But the high sensitivity of the CIS experiment proved crucial to the study, along with a specially developed filtering technique.

The plasmaspheric wind. Credit: ESA/ATG medialab

"After long scrutiny of the data, there it was, a slow but steady wind, releasing about 1 kg of plasma every second into the outer magnetosphere: this corresponds to almost 90 tonnes every day. It was definitely one of the nicest surprises I've ever had!"

At this rate, the mass loss is a negligible contribution to the depletion of Earth's atmosphere, whose mass amounts to over 1018 kg. However, this constant outflow plays a significant role in the supply of plasma to the outer magnetosphere, surpassed in efficiency only by the solar wind, which is also a steady source, and by the occasional and powerful plumes.

"This discovery confirms that Earth's ionosphere and plasmasphere feed the magnetosphere on a regular basis, and not only during active periods," comments Philippe Escoubet, Cluster Project Scientist at ESA. "This allows us to study Earth's atmospheric loss in great detail and to compare it with similar phenomena that occur on other planets in the Solar System at different rates, depending on the intensity of each planet's magnetic field."

Notes for editors:

The study presented here is based on data gathered with the Cluster Ion Spectrometry (CIS) experiment on board the Cluster spacecraft on three occasions in 2001, on two occasions in 2002 and once in 2006.

Cluster is a constellation of four spacecraft flying in formation around Earth. It is the first space mission able to study, in three dimensions, the natural physical processes occurring within and in the near vicinity of the Earth's magnetosphere. Launched in 2000, it is composed of four identical spacecraft orbiting the Earth in a pyramidal configuration, along a nominal polar orbit of 4 × 19.6 Earth radii (1 Earth radius = 6380 km). Cluster's payload consists of state-of-the-art plasma instrumentation to measure electric and magnetic fields over wide frequency ranges, and key physical parameters characterising electrons and ions from energies of near 0 eV to a few MeV. The science operations are coordinated by the Joint Science Operations Centre (JSOC) at the Rutherford Appleton Laboratory, United Kingdom, and implemented by ESA's European Space Operations Centre (ESOC), in Darmstadt, Germany.

Related publications:

I. Dandouras, "Detection of a plasmaspheric wind in the Earth's magnetosphere by the Cluster spacecraft", 2013, Annales Geophysicae, 31, 1143-1153, doi:10.5194/angeo-31-1143-2013:
http://sci.esa.int/cluster/object/index.cfm?fobjectid=51993

J. F. Lemaire & R. W. Schunk, "Plasmaspheric wind", 1992, Journal of Atmospheric and Terrestrial Physics, vol. 54, p. 467-477: http://sci.esa.int/cluster/object/index.cfm?fobjectid=51980

Related links:
Space Weather: http://sci.esa.int/cluster/object/index.cfm?fobjectid=33273

Cluster Mission Home: http://sci.esa.int/cluster

Images, Video, Text, Credits: ESA / ATG medialab.

Greetings, Orbiter.ch

Launch of Indian PSLV C22 Rocket with IRNSS-1 satellite











ISRO - Indian Space Research Organization logo.


July 2, 2013

video
 Launch of Indian PSLV C22 Rocket with IRNSS-1

An Indian Polar Satellite Launch Vehicle (PSLV) succesfully launched from India today, July 1st 2013 at 18:11 UTC carrying the first of seven IRNSS satellites into orbit. Indian Regional Navigation Satellite System (IRNSS) will provide real time navigation and time data to multiple users.

Indian Regional Navigation Satellite System (IRNSS) description. Image credit: thehindu.com

This was the very first night launch of the Indian Polar Satellite Launch Vehicle which uses four stages.


Image above: India has successfully put the country’s first Navigation Satellite into orbit on Monday. A Polar Satellite Launch Vehicle blasted off from the Satish Dhawan Space Center on India’s East coast at 18:11 UTC and made a flawless ascent mission delivering the IRNSS-1A spacecraft to its intended orbit about 20 minutes after launch. The flight was declared a complete success – marking the birth of India’s own navigation constellation, the Indian Regional Navigation System that will cover the country and surrounding areas. Credit ISRO.


Image above: LIFTOFF of an Indian PSLV from Satish Dhawan carrying India’s first navigation satellite. India’s first navigation satellite has arrived in orbit. Photo Screen Capture from ISRO TV.

 Indian Regional Navigation Satellite System (IRNSS). Credit: ISRO

 For more information about Indian Space Research Organization (ISRO), visit: http://www.isro.org/

Images (mentioned), Video, Text, Credits: ISRO / ISRO TV.

Best regards, Orbiter.ch

CryoSat maps largest-ever flood beneath Antarctica







ESA - CryoSat 2 Mission logo.

2 July 2013

ESA’s CryoSat satellite has found a vast crater in Antarctica’s icy surface. Scientists believe the crater was left behind when a lake lying under about 3 km of ice suddenly drained.

Far below the thick ice sheet that covers Antarctica, there are lakes of fresh water without a direct connection to the ocean. These lakes are of great interest to scientists who are trying to understand water transport and ice dynamics beneath the frozen Antarctic surface – but this information is not easy to obtain.

Site of crater

One method is to drill holes through kilometres of ice to the water – a difficult endeavour in the harsh conditions of the polar regions.

But instead of looking down towards the ice, a team of European scientists is looking to the sky to improve our understanding of subglacial water and its transport.

By combining new measurements acquired by CryoSat with older data from NASA’s ICESat satellite, the team has mapped the large crater left behind by a lake, and even determined the scale of the flood that formed it.

From 2007 to 2008, six cubic kilometres of water – about the same amount that is stored in Scotland’s Loch Ness – drained from the lake, making it the largest event of its kind ever recorded.

3D view

That amount of water equals a tenth of the melting that occurs beneath Antarctica each year.

Since the end of 2008, the lake appears to be refilling but six times slower than it drained. It could take decades to reform.

The study, published recently in Geophysical Research Letters, highlights CryoSat’s unique capacity to map changes in Antarctica’s subglacial lakes in 3D, and sheds new light on events at the base of the ice sheet.

CryoSat carries a radar altimeter that can ‘see’ through clouds and in the dark, providing continuous measurements over areas like Antarctica that are prone to bad weather and long periods of darkness.

The radar can measure both the area and depth of ice craters in high resolution, allowing scientists to calculate its volume accurately.

ESA's ice mission CryoSat

“Thanks to CryoSat, we can now see fine details that were not apparent in older satellite data records,” said Dr Malcolm McMillan from the UK’s University of Leeds and lead author of the study ‘Three-dimensional mapping by CryoSat-2 of subglacial lake volume changes’.

With every subglacial lake, there is hope of finding prehistoric marine life. The rapid draining and apparent refilling of this lake, however, suggests this was not the first time water has drained from the lake.

“It seems likely that the flood water – and any microbes or sediments it contained – has been flushed into the Southern Ocean, making it difficult to imagine that life in this particular lake has evolved in isolation,” said Prof. Andrew Shepherd, a co-author of the study.

About 400 lakes have been discovered at the base of the Antarctic ice sheet. When they drain, they disrupt subglacial habitats and can cause the ice above to slide more quickly into the sea.

Related links:

‘Three-dimensional mapping by CryoSat-2 of subglacial lake volume changes’: http://onlinelibrary.wiley.com/doi/10.1002/grl.50689/pdf

Geophysical Research Letters: http://www.agu.org/journals/gl/

University of Leeds: http://www.leeds.ac.uk/

British Antarctic Survey: http://www.antarctica.ac.uk/

University College London: http://www.ucl.ac.uk/

ICESat mission: http://icesat.gsfc.nasa.gov/

CryoSat - An Earth Explorer: http://www.esa.int/Our_Activities/Observing_the_Earth/CryoSat/An_Earth_Explorer
   
CryoSat: an icy mission: http://www.esa.int/Our_Activities/Observing_the_Earth/CryoSat/CryoSat_an_icy_mission

Images, Text, Credits: ESA / M. McMillan / AOES Medialab.

Cheers, Orbiter.ch

The Proton-M rocket with three Glonass satellites crashed after takeoff












Russian Navigation Satellites Glonass patch.

July 2, 2013

A Russian Proton-M rocket carrying three GLONASS navigation satellites crashed soon after takeoff from Kazakhstan’s Baikonur cosmodrome.

video
Proton-M with three Glonass satellites liftoff and crash

Immediately after takeoff, the rocket swerved to one side, tried to correct itself, but instead veered in the opposite direction. It then flew horizontally and started to come apart with its engines in full thrust.

Making a huge arch in the air, the rocket plummeted back to earth and exploded on impact close to another launch pad used for Proton commercial launches.

The crash was broadcast live across the country and fears of a possible toxic fuel leak immediately surfaced following the incident. While no such leak has been confirmed, the rocket was initially carrying over 600 tons of toxic propellants.

There have reportedly been no casualties to surroundings structures and the town of Baikonur was not affected. Taking into account the Proton-M rocket and three GLONASS satellites, the failed launch has potentially cost the Russian space industry around $200 million, reported Rossiya24 TV channel.

An accident board headed by Aleksandr Lopatin, deputy head of Russia’s space agency Roskosmos, has been created to investigate the crash.

The emergency ministry of Kazakhstan has warned that toxic fuel from the rocket could pose an ecological threat to the surrounding area.

A cloud of toxic smoke emanating from the burning fuel has led to the evacuation of the area in the immediate vicinity to the crash site.

Proton-M crash sequence (screen capture from the video)

622,000 Kilograms of very toxic propellants are aboard a three-stage of the Proton rocket at the liftoff. Experts point to engine failure as the likely cause of the crash.

"It's either the control system or the engine that has caused the accident. If the accident occurred in the first 10 to 20 seconds, than the engine is likely to be the cause," a source in the space agency told RIA.

An Interfax-Kazakhstan source at the cosmodrome said the rocket was out of control from the moment it took off from the launch pad.

“In line with its program, once a malfunction was detected, the rocket boosted to take itself away from the launch pad and fell about one kilometer from it,” the source said, adding that initial telemetry data suggests that the problem occurred in one of the stability guidance jet engines.

There will be no launches from Baikonur for about two-three months, a source in Russia’s space industry told RIA Novosti news agency.

“There will be no launches of Proton-M rockets while the investigation is underway. In two-three days we will know what exactly happened to the rocket. This is a well-known rocket, and the reason for the crash is the human factor and a production failure,” the source said.

“We’ve had similar accidents at Baikonur before. After the area is cleaned up, launches will resume – in two-three months,” the source continued.

Proton-M crash (screen capture from the video)

Igor Marinin, Editor-in-Chief of Russia’s Cosmonautics News magazine told RT that there have not been any rocket crashes during the  first seconds of flight for at least ten years in the Russian space industry.  “This is a phenomenal accident,” he said.

The Proton-M uses highly toxic heptyl fuel, the expert said, but “it is burning out right now so the consequences will be minor. The major threat is poisonous fumes from the burning fuel and the major task now is to make sure that nobody gets into the heptyl smoke.”

The crashed Proton-M rocket employed a DM-03 booster, which was being used for the first time since December 2010, when another Proton-M rocket with the same booster failed to deliver yet another three GLONASS satellites into orbit, crashing into the Pacific Ocean some 1,500 kilometers from Honolulu.

After the 2010 crash, the investigative commission concluded that technicians miscalculated the amount of fuel needed for the DM-3 rocket booster.

Tuesday’s incident was the fifth launch of a Proton-M rocket in 2012 and the 388th overall launch of a Proton rocket.

The Proton-M booster rocket with a DM-03 (Roscosmos Press Service)

The next Proton-M launch is scheduled for July 21, though it will likely be delayed pending an investigation. It is supposed to deliver a commercial ASTRA 2E broadcast satellite for Europe into orbit.

GLONASS is a network of Russian navigation satellites designed to ensure global positioning, and is viewed as a direct rival to the American Global Positioning System (GPS). Its worldwide operation requires 24 working satellites.

There are currently 28 GLONASS satellites in orbit, 23 of which are in operation, four in reserve and one next generation GLONASS-K satellite undergoing tests.

By 2020 Russia intends to spend over 300 billion rubles ($9 billion) on Glonass.

Russia has already conducted 15 launches from Baikonur and Plesetsk cosmodromes in 2013 and 23 more launches are expected to be made by the end of the year.

ROSCOSMOS Press Release: http://www.federalspace.ru/main.php?id=2&nid=20191

Images, Video, Text, Credits: Press Service of the Russian Federal Space Agency (Roscosmos PAO) / ROSCOSMOS / RIA Novosti.

Greetings, Orbiter.ch

lundi 1 juillet 2013

Space Station Gets an Attitude Adjustment for Solar Science












ISS - International Space Station patch.

July 1, 2013

The sun lightens our world and enlightens our scientists as they look to our closest star for a better understanding of solar activity and what it means for our planet. Unique data from solar studies help researchers build on their knowledge of the Earth’s atmosphere and climate change. June 30 marked the second time the International Space Station literally went out of its way to accommodate this research by providing a better viewing opportunity to meet Solar facility science objectives.

“The European scientists requested that we reposition the station slightly because by having this period of time they could bridge over the two Solar observing visibility windows, allowing them to view the sun for a full solar rotation without interruption,” said International Space Station Program Scientist Julie Robinson, Ph.D. “The International Space Station Program took a look at the request and was able to change the station's position to increase science return.”


Image above: The International Space Station's change in position accommodates solar research from an orbital vantage point by lengthening the window of time to observe a full rotation of the sun for data collection from the Solar observatory. Image Credit: NASA.

The first station adjustment took place between Dec. 1 and 11, 2012, when the attitude of the orbiting laboratory was temporarily altered by about 7.5 degrees to provide a longer viewing time of the sun for the European Space Agency’s (ESA) Solar observatory on the External Payload Facility of the Columbus module. This summer adjustment to the space station’s position offers an additional opportunity to follow an entire solar rotation, approximately 27 days as determined by viewing sunspots from Earth.

“A very important contribution from the Solar ‘bridging’ measurements is the possibility it brings to perform inter-comparisons over an entire period of a Solar rotation with data from other solar instruments in orbit (e.g. a comparison of ESA’s Solar-SOLACES data and NASA's SDO/EVE data),” said ESA Solar Project Scientist Astrid Orr, Ph.D. “The December bridging already shows that these particular data sets agree extremely well with each other.”



Image above: NASA's Solar Dynamics Observatory (SDO) captured this image of an M5.7-class flare on May 3. This image shows light in the 131-angstrom wavelength, a wavelength of light that can show material at the very hot temperatures of a solar flare and that is typically colorized in teal. Image Credit: NASA.

The measurements for this Solar window observation are planned to run from June 18 to July 23, with the bridging event beginning on July 1. Normally viewing from the station only allows for short visibility windows of 10 to 12 days at a frequency of about once a month. After that timeframe, the observation window is blocked by the structure of the station itself, such as the solar arrays. Changing the position of the station increases the visibility of the sun, enabling scientists to view a full rotation from the orbital vantage point.

The Solar observatory launched to the station in February 2008 and currently houses two active investigations: Solar-SOLACES and Solar-SOLSPEC. Solar-SOLACES, which stands for Solar Auto-Calibrating Extreme UV/UV Spectrophotometers, collects data between 15 and 220 nanometers (nm) for extreme-ultraviolet/ultraviolet solar spectral irradiance. Solar-SOLSPEC, which stands for Solar Spectral Irradiance Measurements, measures between 180 to 3,000 nm for absolute solar spectral irradiance. Solar irradiance measurements tell scientists how much energy reaches Earth’s atmosphere from the sun during any given period of time.


Image above: A view of the zenith and forward sides of the International Space Station’s Columbus module showing the Monitoring on the External Payload Facility of Columbus (Solar), European Technology Exposure Facility (EuTEF) and Materials International Space Station Experiment (MISSE) facility. Image Credit: NASA.

The goal of these studies is to gain accurate solar spectral irradiance measurements to understand variations in our environment due to solar radiation. With solar activity increasing, the timing of this adjustment will accommodate the investigations for improved science returns. These data can contribute to improved modeling of sunspots and other solar phenomena. The information also contributes to atmospheric and climatic models, helping researchers to predict sun and space weather activities.

“The bridging makes it possible for the scientists to develop a method for ‘melting’ both sets of data into one reference set of data in absolute physical values for the science community, which includes both solar physicists and climate researchers,” said Orr.

The June viewing window coincides with the Northern Hemisphere summer solstice—on the other side of the globe, this time period corresponds to the Southern Hemisphere winter solstice. During both the summer and winter solstices the gap between viewing opportunities is less than 10 days, making it possible to bridge two visibility windows for a full sun rotation with minimum adjustment to the station's attitude angle.


The image above shows the location along with a close up view of the European Space Agency's European Technology Exposure Facility (EuTEF) platform located externally on the Columbus module. EuTEF houses nine experiments including Earth Viewing Camera (EVC). Image Credit: NASA.

The station’s orbit is turned at this time so that it is mostly sunlit, giving the instruments optimal opportunity for measurements. This will help to meet the Solar science team’s requirements to observe the sun through a full solar rotation, which would not be possible without the station adjustment, due to orbital mechanics and maneuver limitations of the Solar platform. After the observations complete, the station will return to its standard attitude. The investigations will continue to collect data using shorter observation periods.

“The Solar detectors perform very accurate measurements of the sun's flux: they are measurements in absolute values. In other words, the real amount of flux emitted by the sun in physical units,” said Orr. “This may sound trivial but it is in fact quite difficult to achieve. Many detectors looking at the sun provide only measurements in relative units. On the other hand, absolute measurements are important in order to understand the amount of energy that the sun is emitting and that we receive at the Earth. Like, if somebody has a fever and you are trying to measure their temperature: you can put your hand on their forehead and say that it's hot, or else you can actually measure the temperature with a thermometer. It is useful if the thermometer that you are using has its units stated correctly, otherwise your measurement will be of little use.”

This is an exciting time for solar scientists because with the full solar rotation observation, they will have a second chance to compare their Solar data with results from other measurement instruments. This will give researchers a more complete data set to work with for their studies on the impact of the sun’s radiation on our planet’s environment.

ESA requested an additional temporary change to the space station’s attitude for a third viewing opportunity during Northern Hemisphere's winter solstice, which takes place from Nov. 29 to Dec. 8. “The Solar science team estimates that three ‘science visibility window’ bridging maneuvers will provide them a sufficient level of statistics in their measurements,” said Orr. “Three is a minimum, but it would be sufficient.”

For more information about the International Space Station, visit: http://www.nasa.gov/mission_pages/station/

Images (mentioned), Text, Credits: NASA / International Space Station Program Science Office / NASA's Johnson Space Center / Jessica Nimon.

Greetings, Orbiter.ch