vendredi 20 juin 2014

QuikScat's Eye on Ocean Winds Lives On with RapidScat

NASA - QuikScat Mission patch.

June 20, 2014

Image above: Using data from NASA’s QuikScat, weather forecasters were able to predict hazardous weather events over oceans 6 to 12 hours earlier than before these data were available. Orange areas show where winds are blowing the hardest and blue shows relatively light winds. Image Credit: NASA.

Today (June 19) marks the 15th anniversary of the launch of NASA's QuikScat, a satellite sent for a three-year mission in 1999 that continues collecting data. Built in less than 12 months, QuikScat has watched ocean wind patterns for 15 years and improved weather forecasting worldwide. Despite a partial instrument failure in 2009, it provides calibration data to international partners.

On this anniversary, the mission's team is preparing to calibrate ISS-RapidScat, the successor that will maintain QuikScat’s unbroken data record. After its launch in a few months, RapidScat will watch ocean winds from the International Space Station (ISS) for a two-year mission.

Much like QuikScat, ISS-RapidScat was built in less than two years and at a fraction of its predecessor’s budget. Both missions are testaments to ingenuity, craftsmanship and speedy construction in the name of improving our understanding of Earth’s winds.

“Both ISS-RapidScat and QuikScat came about to react quickly to the failure of another spaceborne instrument,” said Ernesto Rodriguez, project scientist for the ISS-RapidScat mission at NASA’s Jet Propulsion Laboratory, Pasadena, California. “What differentiates these missions is cost and risk: RapidScat had to be built with a fraction of the QuikScat budget, and the mission accepted a much riskier approach,” Rodriguez said. RapidScat was constructed primarily from QuikScat’s spare parts and will be the first scatterometer to berth on the International Space Station.

Scatterometers help scientists estimate the speed and direction of winds at the ocean’s surface by sending microwave pulses to Earth’s surface. Strong waves or ripples scatter the microwaves, sending some of them back toward the scatterometer. Based on the strength of this backscatter, scientists can estimate the strength and direction of the wind at the ocean’s surface.

Scatterometer data are critical for observing global weather patterns. They also help ocean fishermen decide where to fish, ship captains choose shipping lanes and researchers track hurricanes, cyclones and El Niños.

“The usefulness of this wind measurement is enormous,” said JPL’s Jim Graf, who served as project manager for the QuikScat mission in the 1990s and is now the deputy director of JPL’s Earth Science and Technology Directorate. “One of the dominant factors in understanding the climate is to assess what is happening in the ocean circulation. And one of the dominant factors in ocean circulation is the wind at the surface, which is what scatterometers measure.”

Image above: QuikScat could detect differences in average wave height much smaller than inch (a centimeter) during its 15 years watching ocean winds. Image Credit: Wikimedia Commons.

NASA launched its first scatterometer satellite in 1978 and its second instrument, the NASA Scatterometer (NSCAT), on a Japanese satellite in 1996. Each lasted less than a year, but collected hundreds of times more data about ocean winds than ships or buoys and improved weather forecasts from the National Oceanic and Atmospheric Administration (NOAA).

But the spacecraft carrying NSCAT malfunctioned in 1997. Immediately, a team of JPL scientists and engineers raced to get a scatterometer satellite back into space.

“We had the idea that a partially developed spacecraft bus could be mated with an advanced version of the instrument that was already under development, and we could get something up quickly. So we went to NASA, and they said, ‘Okay, let’s give it a shot, but we want you to be ready to go one year from the go-ahead,’” Graf said. “And so we took off running, and we didn’t stop for a whole year.”

In that year, Ball Aerospace & Technologies Corp., Boulder, Colorado, built the QuikScat satellite bus while JPL finished the new SeaWinds scatterometer instrument. It launched in 1999. For the next decade, QuikScat made about 400,000 daily measurements of wind speed and direction. Over 15-mile (25-kilometer) segments of ocean, its measurements were detailed enough to estimate average wind speed within 6 feet (2 meters) per second.

The SeaWinds instrument on QuikScat used a rotating antenna to measure a swath of Earth’s surface 1,118 miles (1,800 kilometers) wide -- about the distance from Los Angeles to Seattle. As QuikScat flew, the rotations overlapped to cover more than 90 percent of Earth’s surface every day.

But by the end of 2009, long after the expected end of QuikScat’s mission, the lubricant coating the antenna’s bearings dried up. Instead of tracing a round swath on Earth’s surface, it pointed straight down and only watched the waves directly below it. Still, those data were sufficient to help calibrate newer satellites.

QuikScat satellite. Image Credit: NASA

“Since 2009, we’ve been able to keep QuikScat operating quite successfully,” said QuikScat Project Manager Rob Gaston of JPL. “We used QuikScat’s highly successful backscatter measurements, which were well understood and had demonstrated stability, as a calibration standard for many instruments, including other scatterometers.” The European Space Agency and Indian Space Research Organization have both used QuikScat data to calibrate scatterometers in the last five years.

QuikScat’s final task will be to calibrate its successor, RapidScat. The satellite will continue collecting data until April 2015, when it will be decommissioned after nearly 16 years in orbit.

RapidScat, like QuikScat, was built in a fraction of the timeline for most missions. The two missions even share hardware: JPL engineers used SeaWinds test parts to build much of RapidScat, which also uses a rotating dish antenna.

RapidScat will launch aboard a SpaceX Dragon resupply mission this summer. Flying in the space station’s orbit means RapidScat will spend more time observing Earth's tropics than previous scatterometer satellites, which orbited farther north and south.

“RapidScat will be able to, for the first time, map the evolution of winds as the day progresses, which is important for understanding how clouds and precipitation develop, especially in the tropics, which are key regions in Earth's climate system,” Rodriguez said. “It will provide a common reference to tie all of these measurements together.”

Together with scatterometers managed by India and Europe, RapidScat will maintain the continuous climate record QuikScat began while adding its own unique perspective from orbit.

For more information about ISS-RapidScat, visit:

For more information about QuikScat, visit:

NASA monitors Earth's vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

For more information about NASA's Earth science activities in 2014, visit:

Images (mentioned), Text, Credits: NASA.


Science and spacewalks on Space Station

ESA - Blue Dot Mission patch.

20 June 2014

Flying over Earth

Three weeks into ESA astronaut Alexander Gerst’s Blue Dot mission on the International Space Station and the new arrival is now spending more time on scientific research in the microgravity laboratory.

Alexander has worked on controlled fires in space and continuously monitored his sleep patterns, at the same time as making sure the orbital outpost is working at full capacity.

Apart from continuing the long-term studies on eyes and headaches in space, Alexander recorded his temperature and hormones over 36 hours to understand his sleep patterns.

Columbus laboratory

Astronauts on the Station witness 16 sunrises and sunsets each day – whereas on Earth our bodies rely on sunlight to kick-start hormone production that make us sleepy or wake us up.

Researchers are interested to see how the unique 90-minute days influence sleep. Aside from making sure astronauts feel awake at critical moments, this research in space allows sleep specialists to test theories that they couldn’t anywhere else.

Alexander acted as a weightless firestarter and firefighter this week when he ignited small samples of fuels safely contained in ESA’s glovebox to see how they burn in space. He volunteered as a fireman before becoming an astronaut, so the experiment was in good hands.

This research will improve computer models for fire detectors and extinguishers, both in space and on Earth. He explained the experiment via Twitter: “Burning things in space for better fire safety on Earth.”

Burning fuel in space

Elsewhere, Alexander took samples of his blood and saliva and collected data on his eyes, his skin and his body so researchers can understand how astronauts react to weightlessness.

Other notable experiments included the harvesting of space-grown salads – unfortunately for the astronauts, they are not allowed to eat them.


Yesterday, cosmonauts Oleg Armetyev and Alexander Skvortsov spent over six hours working outside the Station to install an antenna, take samples and move experiments. Meanwhile the four astronauts inside continued their science activities.

Checking spacesuit

Earlier, Alexander thoroughly checked a newly arrived US spacesuit. Before being declared ready for use, he had to make sure it had survived its climb into space.


Image above: Russian cosmonauts Alexander Skvortzov and Oleg Artemyev spent over six hours working outside the International Space Station on 19 June 2014. This picture was taken by ESA astronaut Alexander Gerst from inside the orbital outpost.

Alexander even had time this week for educational activities for Earth Guardian, inspiring children to observe geographical features such as oceans, rivers, landscapes, mountains and forests in their areas during the summer holidays.

Related links:

All about Blue Dot:

Connect with Alexander Gerst:

Where is the International Space Station?:

Images, Text, Credits: ESA / NASA.


Beautiful Brazil

ESA - Proba-V Mission logo.


Proba-V imaging Brazil

As football fans worldwide keep their eyes trained on Brazil, ESA’s Proba-V minisatellite captures the entire country in a single image.

The Andean Plateau, or Altiplano, of neighbouring Bolivia, including Lake Titicaca and the giant Salar Uyuni salt flat, are visible towards the scene’s western edge.

Proba is smaller than a cubic metre but its view spans a mighty 2250 km. It reveals details 300 m across but the central part of the image is sharper – down to 100 m – as demonstrated in the right-hand image, which shows a detail of the River Negro joining the mighty River Amazon.

Proba-V is a miniaturised ESA satellite tasked with a full-scale mission: to map land cover and vegetation growth across the entire planet every two days.

Artist's view of the Proba-V satellite

The camera’s continent-spanning field of view collects light in the blue, red, near-infrared and mid-infrared wavebands, ideal for monitoring plant and forest growth as well as inland water bodies.

Proba’s images are processed and distributed to hundreds of scientific end users by VITO, Belgium’s Flemish Institute for Technological Research, extending the coverage of previous generations of the Vegetation camera flown on the Spot-4 and Spot-5 satellites.

For more information about Proba-V, visit:

Images, Text, Credits: ESA / BELSPO.


Spacewalk of the Russian cosmonauts completed

ISS - Expedition 40 Mission patch / ROSCOSMOS - Russian Cosmonaut patch.


Roscosmos cosmonauts Alexander Skvortsov and Oleg Artemyev, exit hatch docking module "Pirs"

Exit hatch docking module "Pirs" closed, the crew members MKS-40/41 Roscosmos cosmonauts Alexander Skvortsov and Oleg Artemyev, completed a spacewalk.

Russian cosmonaut duo make first spacewalk outside ISS

Astronauts set to work in the open space in 18 hours 10 minutes Moscow time. During the exit 38 on the Russian segment of the ISS program have completed installation of the external unit AFAR for subsequent installation of communication with Earth via relay satellites of "Ray".

Roscosmos cosmonauts Alexander Skvortsov and Oleg Artemyev

The unit of PVK-2 experiment scientific equipment "decor" was moved in the direction of the instrument compartment of the service module "Zvezda "astronauts check the working condition of locks on the universal workplace implemented reinstallation monoblock TM / TC and SVPI farm carrying scientific equipment MPAC & SEED, and took samples from the outer surface of the window number 2 on the IV plane working compartment within the space experiment "Test".

Roscosmos cosmonaut Alexander Skvortsov

Exit hatch was closed June 20, 2014 at 1:00 34 minutes Moscow time. Alexander Skvortsov and Oleg Artemyev first performed the work in open space, the duration of extravehicular activity was 7:00 24 minutes.

ROSCOSMOS Press Release:

Images, Video, Text, Credits: Roscosmos press service / ROSCOSMOS / Euronews / NASA TV / Translation: Aerospace.

Best regards,

Swiftly moving gas streamer eclipses supermassive black hole

ESA - Hubble Space Telescope logo.

20 June 2014

Astronomers have discovered strange and unexpected behaviour around the supermassive black hole at the heart of the galaxy NGC 5548. The international team of researchers detected a clumpy gas stream flowing quickly outwards and blocking 90 percent of the X-rays emitted by the black hole. This activity could provide insights into how supermassive black holes interact with their host galaxies.

The discovery of the unusual behaviour in NGC 5548 is the result of an intensive observing campaign using major ESA and NASA space observatories, including the NASA/ESA Hubble Space Telescope [1]. In 2013 and 2014 the international team carried out the most extensive monitoring campaign of an active galaxy [2] ever conducted.

There are other galaxies that show gas streams near a black hole, but this is the first time that a stream like this has been seen to move into the line of sight.

Supermassive black hole at the heart of NGC 5548

The researchers say that this is the first direct evidence for the long-predicted shielding process that is needed to accelerate powerful gas streams, or winds, to high speeds. “This is a milestone in understanding how supermassive black holes interact with their host galaxies,” says Jelle Kaastra of the SRON Netherlands Institute for Space Research, who led the research team [3]. “We were very lucky. You don’t normally see this kind of event with objects like this. It tells us more about the powerful ionised winds that allow supermassive black holes in the nuclei of active galaxies to expel large amounts of matter. In larger quasars than NGC 5548, these winds can regulate the growth of both the black hole and its host galaxy.”

As matter spirals down into a black hole it forms a flat disc, known as an accretion disc. The disc is heated so much that it emits X-rays, near to the black hole, and less energetic ultraviolet radiation further out. The ultraviolet radiation can create winds strong enough to blow gas away from the black hole, which otherwise would have fallen into it. But, the winds only come into existence if their starting point is shielded from X-rays.

Earlier observations had seen the effects of both X-rays and ultraviolet radiation on a region of warm gas for away from the black hole, but these most recent observations have shown the presence of a new gas stream between the disc and the original cloud. The newly discovered gas stream in the archetypal Seyfert galaxy NGC 5548 — one of the best-studied sources of this type over the past half-century — absorbs most of the X-ray radiation before it reaches the original cloud, shielding it from X-rays and leaving only the ultraviolet radiation. The same stream shields gas closer to the accretion disc. This makes the strong winds possible, and it appears that the shielding has been going on for at least three years.

Directly after Hubble had observed NGC 5548 on 22 June 2013, the team discovered unexpected features in the data. “There were dramatic changes since the last observation with Hubble in 2011. We saw signatures of much colder gas than was present before, indicating that the wind had cooled down, due to a strong decrease in the ionising X-ray radiation from the nucleus,” said team member Gerard Kriss of the Space Telescope Science Institute in Baltimore, USA.

After combining and analysing data from the six observatories involved, the team was able to put the pieces of the puzzle together. NGC 5548’s persistent wind, which has been known about for two decades, reaches velocities exceeding 3.5 million kilometres per hour. But, a new wind has arisen which is much stronger and faster than the persistent wind.

Artist’s impression of gas filament eclipsing a black hole

“The new wind reaches speeds of up to 18 million kilometres per hour, but is much closer to the nucleus than the persistent wind,” says Kaastra. “The new gas outflow blocks 90 percent of the low-energy X-rays that come from very close to the black hole, and it obscures up to a third of the region that emits the ultraviolet radiation at a distance of a few light-days from the black hole.”

Strong X-ray absorption by ionised gas has been seen in several other sources, and it has been attributed for instance to passing clouds. “However, in our case, thanks to the combined XMM-Newton and Hubble data, we know this is a fast stream of outflowing gas very close to the nucleus,” said team member Massimo Cappi, of INAF-IASF Bologna. “It may even originate from the accretion disc,” added team member Pierre-Olivier Petrucci, of CNRS, IPAG Grenoble.

These results are being published online in the 19 June issue of Science Express.

[1] The observatories include ESA’s X-ray Multi-Mirror Mission (XMM-Newton), the NASA/ESA Hubble Space Telescope, NASA’s Swift, NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR), NASA’s Chandra X-ray Observatory, and ESA's International Gamma-Ray Astrophysics Laboratory (INTEGRAL).

[2] An active galaxy is a galaxy which hosts an active galactic nucleus (AGN). An AGN is a compact region at the centre of a galaxy that has a much higher than normal luminosity. The high level of radiation, sometimes across the whole of the electromagnetic spectrum, is thought to be a result the supermassive black hole at the centre pulling in mass from the surroundings.

[3] The interactions between black holes and their host galaxies are believed to have a fundamental importance on the way galaxies evolve.

Notes for editors:

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


Images of Hubble:

For images and more information about Hubble, visit: and

Image, Text, Credits: ESA/Hubble and NASA/Acknowledgement: Davide de Martin/A. Feild (STScI).


Spitzer Spies an Odd, Tiny Asteroid

NASA - Spitzer Space Telescope logo.

June 20, 2014

Astronomers using NASA's Spitzer Space Telescope have measured the size of an asteroid candidate for NASA's Asteroid Redirect Mission (ARM), a proposed spacecraft concept to capture either a small asteroid, or a boulder from an asteroid. The near-Earth asteroid, called 2011 MD, was found to be roughly 20 feet (6 meters) in size, and its structure appears to contain a lot of empty space, perhaps resembling a pile of rubble. Spitzer's infrared vision was key to sizing up the asteroid.

I Spy a Little Asteroid With My Infrared Eye

Image above: This image of asteroid 2011 MD was taken by NASA's Spitzer Space Telescope in Feb. 2014, over a period of 20 hours. The long observation, taken in infrared light, was needed to pick up the faint signature of the small asteroid (center of frame). Image credit: NASA/JPL-Caltech/Northern Arizona University/SAO.

"From its perch up in space, Spitzer can use its heat-sensitive infrared vision to spy asteroids and get better estimates of their sizes," said Michael Mommert of Northern Arizona University, Flagstaff, lead author of a new study appearing today, June 19, in the Astrophysical Journal Letters. David Trilling, also of Northern Arizona University, leads the team of astronomers.

Image above: How to Measure the Size of an Asteroid Observations of infrared light coming from asteroids provide a better estimate of their true sizes than visible-light measurements. Image credit: NASA/JPL-Caltech.

The Spitzer results confirm that asteroid 2011 MD has characteristics suitable for the ARM proposal, elevating it to the "valid candidate" level. Valid candidates are those asteroids with the right size, mass and rotation rate to be feasibly captured by the robotic spacecraft. Two other valid candidates have been identified so far. (The proposal to capture a boulder from an asteroid involves a different set of criteria.) NASA continues to search for and find new potential candidates using its ground-based asteroid survey programs.

Prior to the Spitzer study, the size of 2011 MD was only very roughly known. It had been observed in visible light, but an asteroid's size cannot be determined solely from visible-light measurements. In visible light alone, for example, a white snowball in space could look just as bright as a dark mountain of cosmic rock. The objects may differ in size but reflect the same amount of sunlight, appearing equally bright.

Image above: The Spitzer Space Telescope whizzes in front of a brilliant, infrared view of the Milky Way galaxy's plane in this artistic depiction. Image credit: NASA/JPL-Caltech.

Infrared light, on the other hand, is a better indicator of an object's true size. This is because an object's infrared glow depends largely on its temperature, not its reflectivity.

From the new Spitzer data, the team was able to measure the size of asteroid 2011 MD. When the infrared and visible-light observations were combined, the asteroid's density and mass could also be measured. The density of 2011 MD is remarkably low -- about the same as water, which agrees with a separate analysis of observations taken in 2011. Since rock is about three times more dense than water, this implies that about two-thirds of the asteroid must be empty space.

What does an asteroid with that much empty space look like? The team doesn't know, but proposes two possible solutions: it might be a collection of loosely bound rocks, like a fleet of flying boulders, or a solid rock with surrounding fine debris.

A similar "rubble-pile" type of composition was also found for asteroid 2009 BD, another valid candidate for ARM. Trilling and colleagues used Spitzer to help pin down the size of that asteroid to roughly 10 to 13 feet (3 or 4 meters).

Image above: Solid as a Rock? Porosity of Asteroids. Asteroids can differ in the degree of porosity, or the amount of empty space that makes up their structures. Image credit: NASA/JPL-Caltech.

In both studies, Spitzer stared at the asteroids for about 20 hours. Such long observations are scheduled more often in Spitzer's "warm" mission, a phase that began in 2009 when the spacecraft ran out of coolant, as planned. Spitzer, which still has two infrared channels that operate without coolant, now specializes in longer, targeted observing campaigns.

"With Spitzer, we have been able to get some of the first measurements of the sizes and compositions of tiny asteroids," said Trilling. "So far, we've looked at two asteroids and found both of them to be really weird -- not at all like the one solid rock that we expected. We're scratching our heads."

The team says the small asteroids probably formed as a result of collisions between larger asteroids, but they do not understand how their unusual structures could have come about. They plan to use Spitzer in the future to study more of the tiny asteroids, both as possible targets for asteroid space missions, and for a better understanding of the many asteroid denizens making up our solar system.

Other authors of the Spitzer paper are: D. Farnocchia, P. Chodas and S. R. Chesley of NASA's Jet Propulsion Laboratory, Pasadena, California; J. L. Hora, G. G. Fazio and H.A. Smith of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts; M. Mueller of the SRON Netherlands Institute for Space Research, Netherlands; and A. W. Harris of the DLR Institute for Planetary Research, Germany.

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.

Through its Asteroid Initiative, NASA is developing a first-ever mission to identify, capture and redirect a near-Earth asteroid to a stable orbit around the moon with a robotic spacecraft. Astronauts aboard an Orion spacecraft, launched by a Space Launch System rocket, will explore the asteroid in the 2020s, returning to Earth with samples. Experience in human spaceflight beyond low-Earth orbit through this Asteroid Redirect Mission will help NASA test new systems and capabilities needed to support future human missions to Mars. The Initiative also includes an Asteroid Grand Challenge, which is seeking the best ideas to find all asteroid threats to human populations and accelerate the work NASA already is doing for planetary defense.

JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.

More information about asteroids and near-Earth objects is available at:

More information about Spitzer is at:

Images (mentioned), Text, Credits: NASA / JLP / Whitney Clavin.


jeudi 19 juin 2014

NASA's Swift Satellite Tallies Water Production of Mars-bound Comet

NASA - SWIFT Mission patch.

June 19, 2014

In late May, NASA's Swift satellite imaged comet Siding Spring, which will brush astonishingly close to Mars later this year. These optical and ultraviolet observations are the first to reveal how rapidly the comet is producing water and allow astronomers to better estimate its size.

"Comet Siding Spring is making its first passage through the inner solar system and is experiencing its first strong heating from the sun," said lead researcher Dennis Bodewits, an astronomer at the University of Maryland College Park (UMCP). "These observations are part of a two-year-long Swift campaign to watch how the comet's activity develops during its travels."

"Fresh" comets like Siding Spring, which is formally known as C/2013 A1, contain some of the most ancient material scientists can study. The solid part of a comet, called its nucleus, is a clump of frozen gases mixed with dust and is often described as a "dirty snowball." Comets cast off gas and dust whenever they venture near enough to the sun.

Image above: This composite of C/2013 A1 (Siding Spring) merges Swift UVOT images taken between May 27 and 29, 2014. Sunlight reflected from the comet's dust, which produces most of the light in this image, appears yellow; violet shows ultraviolet light produced by hydroxyl (OH), a molecular fragment of water. Image Credit: NASA/Swift/D. Bodewits (UMD), DSS.

What powers this activity is the transformation of frozen material from solid ice to gas, a process called sublimation. As the comet approaches the sun and becomes heated, different gases stream from the nucleus, carrying with them large quantities of dust that reflect sunlight and brighten the comet. By about two and a half times Earth's distance from the sun (2.5 astronomical units, or AU), the comet has warmed enough that water becomes the primary gas emitted by the nucleus.

Between May 27 and 29, Swift's Ultraviolet/Optical Telescope (UVOT) captured a sequence of images as comet Siding Spring cruised through the constellation Eridanus at a distance of about 2.46 AU (229 million miles or 368 million km) from the sun. While the UVOT cannot detect water molecules directly, it can detect light emitted by fragments formed when ultraviolet sunlight breaks up water -- specifically, hydrogen atoms and hydroxyl (OH) molecules.

"Based on our observations, we calculate that at the time of the observations the comet was producing about 2 billion billion billion water molecules, equivalent to about 13 gallons or 49 liters, each second," said team member Tony Farnham, a senior research scientist at UMCP. At this rate, comet Siding Spring could fill an Olympic-size swimming pool in about 14 hours. Impressive as it sounds, though, this is relatively modest water emission compared to other comets Swift has observed.

NASA's Swift spacecraft. Image Credit: NASA's Goddard Space Flight Center

Based on these measurements, the team concludes that the icy nucleus of comet Siding Spring is only about 2,300 feet (700 meters) across, placing it at the lower end of a size range estimated from earlier observations by other spacecraft.

The comet makes its closest approach to Mars on Oct. 19, passing just 86,000 miles (138,000 km) from the Red Planet -- so close that gas and dust in the outermost reaches of the comet's atmosphere, or coma, will interact with the atmosphere of Mars.

For comparison, the closest recorded Earth approach by a comet was by the now-defunct comet Lexell, which on July 1, 1770, swept to within 1.4 million miles (2.3 million km) or about six times farther than the moon. During its Mars flyby, comet Siding Spring will pass more than 16 times closer than this. 

Scientists have established that the comet poses no danger to spacecraft now in orbit around Mars. These missions will be pressed into service as a provisional comet observation fleet to take advantage of this unprecedented opportunity.

The Swift observations are part of a larger study to investigate the activity and evolution of new comets, which show distinct brightening characteristics as they approach the sun not seen in other comets. Bodewits and his colleagues single out comets that can be observed by Swift at distances where water has not yet become the primary gas and repeatedly observe them as they course through the inner solar system. This systematic study will help astronomers better understand how comet activity changes with repeated solar heating.

Related links:

Comet to Make Close Flyby of Red Planet in October 2014:

NASA's Hubble Space Telescope Spots Mars-Bound Comet Sprout Multiple Jets:

NASA's Swift Monitors Departing Comet Garradd (4.13.2012):

Swift’s Comet Tally Highlighted in Observatory Webcast (04.03.2009)

NASA's Swift Spies Comet Lulin (02.20.2009):

NASA's Swift Looks to Comets for a Cool View (12.03.2008):

Images (mentioned), Text, Credits: NASA's Goddard Space Flight Center / Francis Reddy.


Rosetta’s comet: expect the unexpected

ESA - Rosetta Mission patch.

19 June 2014

An image snapped earlier this month by ESA’s Rosetta spacecraft shows its target comet has quietened, demonstrating the unpredictable nature of these enigmatic objects.

Comet on 4 June

The picture was captured on 4 June by Rosetta’s scientific camera, and is the most recent full-resolution image from the narrow-angle sensor. It has been used to help fine-tune Rosetta’s navigation towards comet 67P/Churyumov–Gerasimenko, which was 430 000 km away at the time.

Strikingly, there is no longer any sign of the extended dust cloud that was seen developing around nucleus at the end of April and into May, as shown in our last image release. Indeed, monitoring of the comet has shown a significant drop in its brightness since then.

“The comet is now almost within our reach – and teaching us to expect the unexpected,” says the camera’s Principal Investigator Holger Sierks from the Max Planck Institute for Solar System Research in Germany.

“After its onset of activity at the end April, our images are currently showing a comet back at rest.”

Comet on 30 April

While it is not uncommon for comets to display varying levels of activity, it is the first time that scientists have witnessed changes in dust production from such a close distance.

A comet’s ‘coma’ develops as it moves along its orbit progressively closer to the Sun, the increasing warmth causing surface ices to sublimate and gas to escape from its rock–ice nucleus.

As the gas flows away from the nucleus, it also carries a cloud of tiny dust particles out into space, which slowly expands to create the coma.

The warming continues and activity rises as the comet moves ever closer to the Sun. Eventually, pressure from the solar wind causes some of the material to stream out into a long tail.

As comets are non-spherical and lumpy, this process is often unpredictable, with activity waxing and waning as they warm. The observations made over the six weeks from the end of April to early June show just how quickly the conditions at a comet can change.

Since Rosetta’s instruments were reactivated earlier this year after a long hibernation, the scientific and navigation cameras have been regularly acquiring images to help define Rosetta’s trajectory to the comet.

Using this information, the spacecraft has been making a series of manoeuvres that will slowly bring it in line with the comet before their rendezvous in the first week of August.

Four manoeuvres have been completed already – the most recent was yesterday – with six more to go. The last in the sequence is planned for 6 August, when Rosetta will be 100 km from the comet and will embark on a series of complex manoeuvres to bring it closer still.

Rosetta spacecraft

But today, even six weeks and about 165 000 km out, Rosetta’s science instruments have already started collecting data on the comet’s environment and its evolution. 

For example, Rosetta is capable of measuring the coma and determining the rates at which water and gases such as carbon dioxide are being produced, and how those rates change with time. These measurements will provide insight into the chemical makeup of the comet’s surface and interior.

The plasma environment of the comet can also be assessed as the coma develops and interacts with particles in the solar wind.

Later, as it gets even closer, Rosetta will start collecting gas and dust particles from the coma, and analysing them in its miniaturised onboard laboratories.

“It’s great to have started regularly receiving science data, especially after a long 10 year journey towards our destination,” says Matt Taylor, ESA’s Rosetta project scientist. “The variable activity of the comet shows it definitely has personality, which makes us all the more eager to get there to learn just how it ticks.”

Today, the roughly 4 km-wide comet scales to about one pixel in the narrow-angle camera – meaning no details of the nucleus can be discerned. But within a few weeks, Rosetta will be close enough to see far more: by early July, it should span five pixels and by the start of August, 500 pixels.

With that in mind, we will now begin publishing images on a more regular basis. The next image is foreseen on or around 3 July, and then on a weekly basis until rendezvous on 6 August. The images will be published in the Rosetta image gallery and via the Rosetta mission blog.

One thing seems certain: as Rosetta comes ever closer to its destination, more exciting surprises surely await us.

More about Rosetta:

More about OSIRIS:

Rosetta image gallery:

Rosetta mission blog:

Related links:
Rosetta at Astrium:

Rosetta at DLR:

Ground-based comet observation campaign:

Images, Text, Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.

Best regards,

Swarm reveals Earth’s changing magnetism

ESA - SWARM Mission logo.

June 19, 2014

Magnetic field changes

The first set of high-resolution results from ESA’s three-satellite Swarm constellation reveals the most recent changes in the magnetic field that protects our planet.

Launched in November 2013, Swarm is providing unprecedented insights into the complex workings of Earth’s magnetic field, which safeguards us from the bombarding cosmic radiation and charged particles.

Earth's ever-changing magnetic field

This animation above shows changes in Earth’s magnetic field from January to June 2014 as measured by ESA’s Swarm trio of satellites.

The magnetic field protects us from cosmic radiation and charged particles that bombard Earth, but it is in a permanent state of flux. Magnetic north wanders, and every few hundred thousand years the polarity flips so that a compass would point south instead of north. Moreover, the strength of the magnetic field constantly changes – and it is currently showing signs of significant weakening.

The field is particularly weak over the South Atlantic Ocean – known as the South Atlantic Anomaly. This weak field has indirectly caused many temporary satellite ‘hiccups’ (called Single Event Upsets) as the satellites are exposed to strong radiation over this area. Video Credits: ESA/Dot2Dot.

Measurements made over the past six months confirm the general trend of the field’s weakening, with the most dramatic declines over the Western Hemisphere.

But in other areas, such as the southern Indian Ocean, the magnetic field has strengthened since January.

June 2014 magnetic field

The latest measurements also confirm the movement of magnetic North towards Siberia.

These changes are based on the magnetic signals stemming from Earth’s core. Over the coming months, scientists will analyse the data to unravel the magnetic contributions from other sources, namely the mantle, crust, oceans, ionosphere and magnetosphere.

This will provide new insight into many natural processes, from those occurring deep inside our planet to space weather triggered by solar activity. In turn, this information will yield a better understanding of why the magnetic field is weakening.

Earth's magnetic field

“These initial results demonstrate the excellent performance of Swarm,” said Rune Floberghagen, ESA’s Swarm Mission Manager.

“With unprecedented resolution, the data also exhibit Swarm’s capability to map fine-scale features of the magnetic field.”

The first results were presented today at the ‘Third Swarm Science Meeting’ in Copenhagen, Denmark.

Sofie Carsten Nielsen, Danish Minister of Higher Education and Science, highlighted the Danish contribution to the mission. Swarm continues the legacy of the Danish Ørsted satellite, which is still operational, as well as the German Champ mission. Swarm’s core instrument – the Vector Field Magnetometer – was provided by the Technical University of Denmark.

Swarm constellation

Denmark’s National Space Institute, DTU Space, has a leading role – together with 10 European and Canadian research institutes – in the Swarm Satellite Constellation Application and Research Facility, which produces advanced models based on Swarm data describing each of the various sources of the measured field.

“I’m extremely happy to see that Swarm has materialised,” said Kristian Pedersen, Director of DTU Space.

For more information about SWARM mission, visit:

Third Swarm science meeting:

Images, Video (mentioned), Text, Credits: ESA/DTU Space/ATG Medialab.


Small but significant

ESA - Hubble Space Telescope logo.

19 June 2014

Astronomers use Hubble to study bursts of star formation in the dwarf galaxies of the early Universe

GOODS field containing distant dwarf galaxies forming stars at an incredible rate

They may only be little, but they pack a star-forming punch: new observations from the NASA/ESA Hubble Space Telescope show that starbursts in dwarf galaxies played a bigger role than expected in the early history of the Universe.

GOODS field containing distant dwarf galaxies forming stars at an incredible rate (annotated)

Although galaxies across the Universe are still forming new stars, the majority of the stars were formed between two and six billion years after the Big Bang. Studying this early epoch of the Universe's history is key in order to fully understand how these stars formed, and how galaxies have grown and evolved since.

Concept illustration of a grism image

A new study using data from Hubble's Wide Field Camera 3 (WFC3) has allowed astronomers to take a new step forward in understanding this crucial era by peering at a sample of dwarf galaxies in the early Universe and, in particular, a selection of starburst galaxies within this sample. These starburst galaxies form stars at a furiously fast rate, far above the "normal" star formation rate expected of galaxies. Previous studies of starburst galaxies have focussed on analysing mid-range or high-mass galaxies, leaving out the huge number of dwarf galaxies that existed in this era of prolific star formation.

 Zoom into GOODS field containing distant dwarf galaxies forming stars at an incredible rate

It was not previously possible to study these distant small galaxies closely. Astronomers could only observe small galaxies at smaller distances or larger galaxies at greater distances. The highly sensitive infrared capabilities of WFC3 and its unique grism spectroscopy mode [1] have now allowed astronomers to peer at low-mass dwarf galaxies in the distant Universe and to deduce the contribution of the starburst galaxies to the total star formation within dwarf galaxies at that time.

Pan of GOODS field containing distant dwarf galaxies forming stars at an incredible rate

"We already suspected that dwarf starbursting galaxies would contribute to the early wave of star formation, but this is the first time we’ve been able to measure the effect they actually had," says Hakim Atek of the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, lead author of the new paper. "They appear to have had a surprisingly significant role to play during the epoch where the Universe formed most of its stars."

Using grism to find faint dwarf galaxies furiously forming stars

"These galaxies are forming stars so quickly that they could actually double their entire mass of stars in only 150 million years — this sort of gain in stellar mass would take most normal galaxies 1-3 billion years," adds co-author Jean-Paul Kneib, also of EPFL.

This result contributes to a decade-long investigation to understand the links between galaxies' mass and their star-forming activity, and helps to paint a consistent picture of events in the early Universe.

Artist’s impression of starburst regions

As well as adding new insight into how and where the stars in our Universe formed, this new finding will certainly help to unravel the secrets of galactic evolution. It is unusual to find a galaxy in a state of starburst, implying that they are the result of some strange incident, such as a merger, a tidal interaction with another galaxy, or the shockwave from a supernova. By studying these galaxies more closely and understanding how they formed and behaved in their earliest years, astronomers hope to discover the cause of these violent bursts and learn more about galactic evolution throughout the Universe.

A paper based on this research will be published online in The Astrophysical Journal on 19 June 2014.


[1] The grism splits up the light from the galaxies, revealing the distribution of brightness and colour in the Universe. This allows scientists to deduce facts about their chemical composition and distance from Earth that would not be possible without such a detailed view from Hubble's space-based perspective.

Notes for editors:

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

[1] The international team of astronomers in this study consists of Hakim Atek (EPFL, Switzerland); Jean-Paul Kneib (EPFL, Switzerland); Camilla Pacifici (Yonsei University Observatory, Republic of Korea); Matthew Malkan (University of California, USA); Stephane Charlot (Institut d’Astrophysique de Paris,France); Janice Lee(Space Telescope Science Institute,USA); Alejandro Bedregal ( Minnesota Institute for Astrophysics, USA); Andrew J. Bunker (University of Oxford, UK); James W. Colbert (Spitzer Science Center, USA); Alan Dressler (Observatories of the Carnegie Institution for Science, USA); Nimish Hathi(Aix Marseille University, France); Matthew Lehnert (Institut d’Astrophysique de Paris, France); Crystal L. Martin (Dep’t. of Physics, Univ. of Calif, USA); Patrick McCarthy (Observatories of the Carnegie Institution for Science, USA); and Marc Rafelski (Spitzer Science Center, USA); Nathaniel Ross (University of California, USA); Brian Siana (University of California Riverside, USA); and Harry I. Teplitz (Caltech, USA)
More information


Images of Hubble:

Hubblecast 75: Dwarf Galaxies that Pack a Punch:

For images and more information about Hubble, visit: and

Images, Text, Credits: NASA, ESA, the GOODS Team and M. Giavalisco (STScI/University of Massachusetts)/Acknowledgement: H.Atek (EPFL, Switzerland) and J-P.Kneib (EPFL, Switzerland)/Videos: ESA/Hubble, NASA, Martin Kornmesser (ESA/Hubble).

Best regards,

NASA Astronauts David Leestma and Andrew Thomas Retire

NASA patch.

June 19, 2014

NASA has bid farewell to two veteran astronauts who have retired after a combined 66 years of federal service.

David Leestma has retired after more than 44 years of government service. A veteran of three spaceflights, Leestma served as a space shuttle mission specialist on STS-41G in 1984, STS-28 in 1989 and STS-45 in 1992.

Before joining NASA, Leestma served in the U.S. Navy as a pilot and flew missions in the Mediterranean/North Atlantic areas while assigned to the USS John F. Kennedy. He was selected to join the astronaut corps in 1980. After flying in space, Leestma held multiple technical and leadership assignments, including director of Flight Crew Operations. In his last role, Leestma led the Technical Transfer and Commercialization Efforts office at NASA's Johnson Space Center in Houston.

Image above: NASA astronauts David Leestma and Andrew Thomas are retiring from the astronaut corps after a combined 66 years in federal service. Image Credit: NASA.

"From the day we came together as astronaut classmates, Dave stood out as a remarkable leader, friend, and loyal teammate," said NASA Administrator Charles Bolden, who flew with Leestma on shuttle Atlantis' STS-45 mission. "He possessed seemingly infinite wisdom of the space shuttle and all its systems and never ceased to amaze me with his performance. We wish him the best."

Leestma holds a Bachelor of Science degree from the United States Naval Academy, Annapolis, Maryland, and a Master of Science degree from the Naval Postgraduate School in Monterey, California.

A retired Navy captain, Leestma has logged more than 3,500 flight hours. He ends his NASA career having logged more than 23 days in space on three shuttle missions.

Andrew Thomas also has retired from NASA after more than 22 years of service to the agency.

Thomas, who holds a doctorate in mechanical engineering, was selected to join NASA's astronaut corps in 1992. Before joining NASA, Thomas worked in private industry as a research scientist responsible for designing vehicle aerodynamics, flight controls and propulsion systems.

"Andy is an extraordinary researcher, engineer and astronaut who has done it all in his 22 years as a NASA astronaut," said Janet Kavandi, director of Flight Crew Operations at Johnson. "In his 177 days in space over four missions, Andy served as the payload commander for a dedicated research mission, lived aboard the Russian Mir space station, conducted a spacewalk during an International Space Station assembly mission and served a vital role as a crew member on our crucial Return to Flight mission, STS-114, following the tragic Columbia accident. Since his last flight, Andy has helped shape NASA's future through his tireless work supporting the development of future exploration technology. We will miss him deeply."

Thomas traveled to Mir in 1998 to assist in the transition to space station operations. He was the last American to live on Mir and performed numerous life and physical sciences experiments during the course of his stay. His research aboard Mir provided the framework for the multinational cooperation and collaborative research on today's International Space Station.

Thomas held multiple technical and leadership assignments during his NASA career, including deputy chief of the Astronaut Office.

For Leestma's complete biography, visit:

For Thomas' complete biography, visit:

Image (mentioned), Text, Credits: NASA / Joshua Buck / Johnson Space Center / Jay Bolden.


mercredi 18 juin 2014

Five Things We’ll Learn from Orion’s First Flight Test

NASA - Orion Multi-Purpose Crew Vehicle patch.

June 18, 2014

Image above: This computer-generated art shows the launch abort system still attached and the jettison of the service module fairing panels. Image Credit: NASA.

All the superlatives associated with Orion's first mission this year – farthest a spacecraft for humans has gone in 40 years, largest heat shield, safest vehicle ever built – can be dazzling, no doubt. But the reason engineers are chomping at the bit for Orion's first mission is the promise of crucial flight test data that can be applied to the design for future missions.  Orion only has two flight test opportunities before astronauts climb aboard for the first crewed mission in 2021 – so gleaning the maximum information possible from Exploration Flight Test (EFT)-1 in December (and later, Exploration Mission-1 in 2017) is of the highest priority. Here are the top five things the engineers will be paying attention to:

1. Launch Abort System Separation – The launch abort system (LAS) is a key reason that Orion is intended to become the safest spacecraft ever built. In an emergency it could activate to pull the crew module and the astronauts it will carry away from the launch pad and the rocket in milliseconds. Hopefully it’s never needed, and since no crew will fly on EFT-1 the rescue system won’t be active.

NASA Orion Exploration Mission 1 Animation

But even when a launch goes perfectly, the 904-pound LAS jettison motor has to perform flawlessly. If it doesn’t get rid of the LAS 6 minutes and 20 seconds into the mission, there will be no landing – the LAS protects the crew module during ascent, but to do so, it blocks the parachutes that allow Orion to safely splashdown.

Image above: The three panels or fairings encapsulating a stand-in for Orion’s service module successfully detach and fall into the Fairing Catch System during a test Nov. 6, 2013 at Lockheed Martin’s facility in Sunnyvale, Calif. Image Credit: Lockheed Martin.

The Launch Abort System separation is just the first of 17 separations or jettisons that have to happen exactly as planned for the mission to be successful.

2. Parachute Deployment – For EFT-1, Orion will travel 3,600 miles above the Earth so that when it performs its deorbit burn, it will come screaming back into the Earth’s atmosphere at almost 20,000 miles per hour. Before it splashes down in the Pacific Ocean, it needs to slow down to 1/1000th of its entry speed – a relatively gentle 20 miles per hour.

Image above: A test version of NASA’s Orion spacecraft touches down in the Arizona desert after its most complicated parachute test to date. Image Credit: NASA.

Earth’s atmosphere does its part to put on the brakes, but to make landing survivable, Orion relies on its parachute system – primarily two drogue parachutes and three massive mains that together would cover almost an entire football field. They’ve been tested on Earth; test versions of Orion have been dropped from airplanes with a multitude of failure scenarios programmed into the parachute deployment sequence in an effort to make sure that every possibly problem is accounted for.

NASA Tests Orion Spacecraft Parachute Jettison Over Arizona

But the sheer number of possible problems to be tested indicates how complicated the system is – each parachute must deploy at the exact right time, open to the exact right percentages in the exact right stages, and be cut away exactly as planned. And no test on Earth can exactly simulate what the spacecraft will really experience on its return from space.

3. Heat Shield Protection – Before the parachutes even get a chance to deploy, Orion has to make it safely through Earth’s atmosphere. The reason that Orion is traveling so far and coming back in so fast is to give the heat shield a good workout – the idea is to get as close as possible to the temperatures Orion would experience during a return from Mars. At the speed it will be traveling, the temperature should reach almost 4,000 degrees Fahrenheit. At that same temperature, a nuclear reactor would melt down.

Image above: This computer-generated art depicts Orion's heat shield protecting the crew module as it enters the Earth's atmosphere. Image Credit: NASA.

Standing between the crew module and all that heat is no more than 1.6 inches of Avcoat, a material that’s designed to burn away rather than transfer the temperatures back to Orion. Some 20 percent of the Avcoat will erode during the spacecraft’s journey back to Earth, and although it’s not the first time the materials has been used for this purpose, at 16.5 feet wide, Orion’s heat shield is the largest ever built. Technicians filled with Avcoat each of the 320,000 honeycomb cells that make up the shield’s structure by hand, then machined them to the precise fractions of inches called for by the design. Getting it exactly right is all that will get Orion through one of the most dynamic periods of its mission.

4. Radiation Levels – Traveling 15 times farther into space than the International Space Station will take Orion beyond the radiation protection offered by Earth’s atmosphere and magnetic field. In fact, the majority of EFT-1 will take place inside the Van Allen Belts, clouds of heavy radiation that surround Earth. No spacecraft built for humans has passed through the Van Allen Belts since the Apollo missions, and even those only passed through the belts – they didn’t linger.

Future crews don’t plan to spend more time than necessary inside the Van Allen Belts, either, but long missions to deep space will expose them to more radiation than astronauts have ever dealt with before. EFT-1’s extended stay in the Van Allen Belts offers a unique opportunity to see how Orion’s shielding will hold up to it. Sensors will record the peak radiation seen during the flight, as well as radiation levels throughout the flight, which can be mapped back to geographic hot spots.

Image above: The Orion crew module for Exploration Flight Test-1 is shown in the Final Assembly and System Testing (FAST) Cell, positioned over the service module just prior to mating the two sections together. Image Credit: NASA/Rad Sinyak.

5. Computer Function – Orion’s computer is the first of its kind to be flown in space. It can process 480 million instructions per second. That’s 25 times faster than the International Space Station’s computers, 400 times faster than the space shuttle’s computers and 4,000 times faster than Apollo’s.

But to operate in space, it has to be able to handle extreme heat and cold, heavy radiation and the intense vibrations of launches, aborts and landings. And it has to operate through all of that without a single mistake. Just restarting the computer would take 15 seconds; and while that might sound lightning fast compared to your PC, you can cover a lot of ground in 15 seconds when you’re strapped to a rocket.

For more information about the Orion program, visit:

Images (mentioned), Videos, Text, Credit: NASA.

Best regards,