ESA – ESIST

A storm rolls in (Mars)

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According to ESA Top News (This article and its images were originally posted on ESA Top News July 19, 2018 at 06:42AM.)

(Cover Image) Mars dust storm

The high resolution stereo camera on board ESA’s Mars Express captured this impressive upwelling front of dust clouds – visible in the right half of the frame – near the north polar ice cap of Mars in April this year.

It was one of several local small-scale dust storms that have been observed in recent months at the Red Planet, which is currently enduring a particularly intense dust storm season. A much larger storm emerged further southwest at the end of May and developed into a global, planet-encircling dust storm within several weeks.

The intensity of this major event means very little light from the Sun reaches the martian surface, a situation extreme enough that NASA’s 15-year old Opportunity rover has been unable to recharge its batteries and call home: it has been in hibernation mode since mid-June.

Dust storms on Mars occur regularly during the southern summer season when the planet is closer to the Sun along its elliptical orbit. The enhanced solar illumination causes stronger temperature contrasts, with the resulting air movements more readily lifting dust particles from the surface – some of which measure up to about 0.01 mm in size.

Martian dust storms are very impressive, both visually like in this image and in terms of the intensity and duration of the rarer global events, but they are generally weaker compared to hurricanes on Earth. Mars has a much lower atmospheric pressure – less than one hundredth of Earth’s atmospheric pressure at the surface – and martian storms have less than half the typical wind speeds of hurricanes on Earth.

The current storm is being monitored by five ESA and NASA orbiters, while NASA’s Curiosity rover has been observing it from the ground thanks to its nuclear-powered battery. Understanding more about how global storms form and evolve will be critical for future solar-powered missions to Mars.

This colour image was created using data from the nadir channel, the field of view of which is aligned perpendicular to the surface of Mars, and the colour channels of the high-resolution stereo camera. The ground resolution is approximately 16 m/pixel and the images are centred at about 78°N/106°E.

Mars Express is also equipped with the Visual Monitoring Camera that captures daily images of the Red Planet.

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This article and its images were originally posted on [ESA Top News] July 19, 2018 at 06:42AM. All credit to both the author and ESA Top News | ESIST.T>G>S Recommended Articles Of The Day.

Martian atmosphere behaves as one

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According to ESA Top News (This article and its images were originally posted on ESA Top News July 18, 2018 at 09:07AM.)

New research using a decade of data from ESA’s Mars Express has found clear signs of the complex martian atmosphere acting as a single, interconnected system, with processes occurring at low and mid levels significantly affecting those seen higher up.

Understanding the martian atmosphere is a key topic in planetary science, from its current status to its past history. Mars’ atmosphere continuously leaks out to space, and is a crucial factor in the planet’s past, present, and future habitability – or lack of it. The planet has lost the majority of its once much denser and wetter atmosphere, causing it to evolve into the dry, arid world we see today.

However, the tenuous atmosphere Mars has retained remains complex, and scientists are working to understand if and how the processes within it are connected over space and time.

A new study based on 10 years of data from the radar instrument on Mars Express now offers clear evidence of a sought-after link between the upper and lower atmospheres of the planet. While best known for probing the interior of Mars via radar sounding, the instrument has also gathered observations of the martian ionosphere since it began operating in 2005.

“The lower and middle levels of Mars’ atmosphere appear to be coupled to the upper levels: there’s a clear link between them throughout the martian year,” says lead author Beatriz Sánchez-Cano of the University of Leicester, UK.

“We found this link by tracking the amount of electrons in the upper atmosphere – a property that has been measured by the MARSIS radar for over a decade across different seasons, areas of Mars, times of day, and more – and correlating it with the atmospheric parameters measured by other instruments on Mars Express.”

From the polar caps to Mars’ upper atmosphere

The amount of charged particles in Mars’ upper atmosphere – at altitudes of between 100 and 200 km – is known to change with season and local time, driven by changes in solar illumination and activity, and, crucially for this study, the varying composition and density of the atmosphere itself. But the scientists found more changes than they were expecting.

“We discovered a surprising and significant increase in the amount of charged particles in the upper atmosphere during springtime in the Northern hemisphere, which is when the mass in the lower atmosphere is growing as ice sublimates from the northern polar cap,” adds Beatriz.

Mars’ polar caps are made up of a mix of water ice and frozen carbon dioxide. Each winter, up to a third of the mass in Mars’ atmosphere condenses to form an icy layer at each of the planet’s poles. Every spring, some of the mass within these caps sublimates to rejoin the atmosphere, and the caps visibly shrink as a result.

“This sublimation process was thought to mostly only affect the lower atmosphere – we didn’t expect to see its effects clearly propagating upwards to higher levels,” says co-author Olivier Witasse of the European Space Agency, and former ESA Project Scientist for Mars Express.

“It’s very interesting to find a connection like this.”

The finding suggests that the atmosphere of Mars behaves as a single system.

This could potentially help scientists to understand how Mars’ atmosphere evolves over time – not only with respect to external disturbances such as space weather and the activity of the Sun, but also with respect to Mars’ own strong internal variability and surface processes.

Mars Express

Understanding the complex atmosphere of Mars is one of the key objectives of ESA’s Mars Express mission, which has been operating in orbit around the Red Planet since 2003.

“Mars Express is still going strong, with one of its current key objectives being to explore exactly how the martian atmosphere behaves, and how different layers of it are connected to one another,” says ESA Mars Express Project Scientist Dmitri Titov.

“Having a long baseline of data is fundamental to our study of Mars – there’s now over a decade of observations to work with. These data don’t just cover a long time period, but also the entirety of Mars and its atmosphere.

“This wealth of comprehensive and complementary observations by different instruments on Mars Express makes studies like this one possible and, together with ESA’s Trace Gas Orbiter and NASA’s MAVEN mission, is helping us to unravel the secrets of the martian atmosphere.”

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This article and its images were originally posted on [ESA Top News] July 18, 2018 at 09:07AM. All credit to both the author Beatriz Sánchez-Cano and ESA Top News | ESIST.T>G>S Recommended Articles Of The Day.

The Standard Cosmological Model Just Got Confirmed Thanks to an Epic Sky Survey

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According to ScienceAlert (This article and its images were originally posted on ScienceAlert July 18, 2018 at 03:40AM.)

A four-year survey of the entire sky has just delivered results, and they are awesome: we have confirmation that the standard cosmological model, which describes the age, rate of expansion, history and contents of the Universe, is indeed accurate.

For four years, the European Southern Observatory’s Planck satellite sailed the skies, constantly scanning and collecting data so that we could study the radiation from the beginning of the Universe, across the entire sky.

Now, five years after that mission ended, the finalised data is in. It’s as complete and accurate as it possibly can be.

The Planck satellite maps radiation in the microwave wavelength; this radiation was produced very shortly after the Big Bang, just 380,000 years into the existence of our Universe.

It’s important because it’s the earliest we can peer back in time. Prior to this point, the Universe had been completely dark and opaque – but when it cleared, electromagnetic radiation could move freely.

We call this map the cosmic microwave background (CMB); it was originally caused by photons, which became stretched into the microwave wavelength as the Universe expanded.

By studying differences and changes in the CMB across different regions of the sky, astronomers can calculate various characteristics of the Universe as it has evolved, over time. And this is what they did.

The first image of the CMB was published in 2013, corroborating the standard model of cosmology. Then, a second dataset, as well as analyses, came out in 2015. They contained both temperature and polarisation data – but there was a caveat.

Planck scientists felt that the quality of some of the polarisation data in that 2015 release – concerning the orientation of the light waves – was lacking, and was perhaps not good enough to be used for cosmology.

That brings us to this new release, called the legacy release. In the intervening years, the Planck consortium reprocessed the data, comparing it with observations made by other instruments, analyses and experiments. And they are pleased with the results.

“Now we really are confident that we can retrieve a cosmological model based on solely on temperature, solely on polarisation, and based on both temperature and polarisation,” said cosmologist Reno Mandolesi of the University of Ferrara in Italy.

“And they all match.”

The new data still supports the standard cosmological model, and is more accurate and reliable for scientists going forward.

This model is, the consortium believes, an excellent description of the Universe, including the structure and distribution of galaxies; the abundance of normal baryonic matter and cold dark matter; dark energy; and an inflation phase at the very beginning of the Universe.

It hasn’t solved everything, though.

In fact, because the model is now more accurate, it presents an interesting conundrum: the Hubble Constant.

That’s the name given to the rate of the expansion of the Universe. Recently, two telescopes in space teamed up, using Cepheid variable stars to determine the Hubble Constant with just 2 percent uncertainty.

They came up with 73.5 kilometres (45.6 miles) per second per megaparsec.

The problem is that, according to the Planck data, the Hubble Constant is 67.4 kilometres (41.9 miles) per second per megaparsec… with less than one percent uncertainty.

Because there’s no single satisfactory astrophysical solution that can explain this discrepancy, this has led some to suggest that we need some sort of “new physics” to explain it. But it could be something more mundane, too.

“For the moment, we shouldn’t get too excited about finding new physics: it could well be that the relatively small discrepancy can be explained by a combination of small errors and local effects,” said Planck project scientist Jan Tauber of the ESA.

“But we need to keep improving our measurements and thinking about better ways to explain it.”

One couldn’t, actually, expect a better result from any data: confirmation of previous ideas, and some fascinating questions just begging for an answer.

If you’re looking to do some science, or just poke around, the new data has been published free for use on the Planck Legacy Archive website.

Meanwhile, a series of pap

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This article and its images were originally posted on [ScienceAlert] July 18, 2018 at 03:40AM. All credit to both the author MICHELLE STARR and ScienceAlert | ESIST.T>G>S Recommended Articles Of The Day.

ExoMars Has Sent Back its First Images From Mars

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According to Universe Today

On October 19th, 2016, the European Space Agency’s Exobiology on Mars (ExoMars) mission established orbit around Mars. Consisting of the ExoMars Trace Gas Orbiter (TGO) and the Schiaparelli lander, the purpose of this mission is to investigate Mars for past signs of life. And whereas the Schiaparelli unfortunately crashed during deployment, the TGO has managed to begin its mission ahead of schedule.

A few weeks ago, the satellite achieved a near circular orbit around Mars after performing a series of braking maneuvers. Since that time, the orbiter’s Color and Stereo Surface Imaging System (CaSSIS) took a stunning image of the surface. This picture was not only the TGO’s first image of Mars, it was also a test to see if the orbiter is ready to being its main mission on April 28th.

The image captured a 40 km- (25 mi) long segment of the Korolev Crater, which is located high in Mars’ northern hemisphere. The image was a composite of three images in different colors that were taken simultaneously on April 15th, 2018, which were then assembled to produce this color image. The bright material that appears at the edge of the crater is water ice.

As Antoine Pommerol, a member of the CaSSIS science team working on the calibration of the data, explained in a recent ESA press release:

“We were really pleased to see how good this picture was given the lighting conditions. It shows that CaSSIS can make a major contribution to studies of the carbon dioxide and water cycles on Mars.”

Prior to the test phase, the camera team transmitted new software to the TGO, and after a few minor issues, they determined that the instrument was ready to work. The camera is one of four instruments on the TGO, which also carries two spectrometer suites and a neutron detector. The spectrometers began their science mission on April 21st by taking the first sample of the atmosphere to see how its molecules absorb sunlight.

By doing this, the TGO hopes to determine the chemical composition of Mars atmosphere and find evidence of methane and other trace atmospheric gases that could be signatures of active biological or geological processes. Eventually, the camera will help characterize features on the surface that could be related to trace gas sources. Hence the importance of this recent test.

“We aim to fully automate the image production process,” said Nicolas Thomas, the camera’s principal investigator from the University of Bern. “Once we achieve this, we can distribute the data quickly to the science community for analysis.”

A lot of challenges lie ahead, which includes a long period of data collection to bring out the details of rare (or yet to be discovered) trace gases in Mars’ atmosphere. This is necessary since trace gases (as the name would suggest) are present in only very small amounts – i.e. less than 1% of the volume of the planet’s atmosphere. But as Håkan Svedhem – the ESA’s TGO project scientist – indicated, the test image was a good start.

“We are excited to finally be starting collecting data at Mars with this phenomenal spacecraft,” he said. “The test images we have seen so far certainly set the bar high.”

By 2020, the second part of the ExoMars mission is scheduled to launch. This will consist of a Russian surface platform and a European rover landing on the surface in support of a science mission that is expected to last into 2022 or longer. Alongside NASA’s proposed Mars 2020 rover, the Red Planet is due to have several more visitors in the coming years!

Further Reading: ESA

Collapsing star gives birth to a black hole

Astronomers have watched as a massive, dying star was likely reborn as a black hole. It took the combined power of the Large Binocular Telescope (LBT), and NASA’s Hubble and Spitzer space telescopes to go looking for remnants of the vanquished star, only to find that it disappeared out of sight.

It went out with a whimper instead of a bang.

The star, which was 25 times as massive as our sun, should have exploded in a very bright supernova. Instead, it fizzled out—and then left behind a black hole.

“Massive fails” like this one in a nearby galaxy could explain why astronomers rarely see supernovae from the most massive stars, said Christopher Kochanek, professor of astronomy at The Ohio State University and the Ohio Eminent Scholar in Observational Cosmology.

As many as 30 percent of such stars, it seems, may quietly collapse into black holes—no supernova required.

“The typical view is that a star can form a black hole only after it goes supernova,” Kochanek explained. “If a star can fall short of a supernova and still make a black hole, that would help to explain why we don’t see supernovae from the most massive stars.”

He leads a team of astronomers who published their latest results in the Monthly Notices of the Royal Astronomical Society.

Among the galaxies they’ve been watching is NGC 6946, a spiral galaxy 22 million light-years away that is nicknamed the “Fireworks Galaxy” because supernovae frequently happen there—indeed, SN 2017eaw, discovered on May 14th, is shining near maximum brightness now. Starting in 2009, one particular star, named N6946-BH1, began to brighten weakly. By 2015, it appeared to have winked out of existence.

A team of astronomers at The Ohio State University watched a star disappear and possibly become a black hole. Instead of becoming a black hole through the expected process of a supernova, the black hole candidate formed through a “failed supernova.” Credit: NASA’s Goddard Space Flight Center/Katrina Jackson

After the LBT survey for failed supernovas turned up the star, astronomers aimed the Hubble and Spitzer space telescopes to see if it was still there but merely dimmed. They also used Spitzer to search for any infrared radiation emanating from the spot. That would have been a sign that the star was still present, but perhaps just hidden behind a dust cloud.

All the tests came up negative. The star was no longer there. By a careful process of elimination, the researchers eventually concluded that the star must have become a black hole.

It’s too early in the project to know for sure how often stars experience massive fails, but Scott Adams, a former Ohio State student who recently earned his doctorate doing this work, was able to make a preliminary estimate.

“N6946-BH1 is the only likely failed supernova that we found in the first seven years of our survey. During this period, six normal supernovae have occurred within the galaxies we’ve been monitoring, suggesting that 10 to 30 percent of massive stars die as failed supernovae,” he said.

“This is just the fraction that would explain the very problem that motivated us to start the survey, that is, that there are fewer observed supernovae than should be occurring if all massive stars die that way.”

To study co-author Krzysztof Stanek, the really interesting part of the discovery is the implications it holds for the origins of very massive black holes—the kind that the LIGO experiment detected via gravitational waves. (LIGO is the Laser Interferometer Gravitational-Wave Observatory.)

It doesn’t necessarily make sense, said Stanek, professor of astronomy at Ohio State, that a massive star could undergo a supernova—a process which entails blowing off much of its outer layers—and still have enough mass left over to form a massive black hole on the scale of those that LIGO detected.

“I suspect it’s much easier to make a very massive black hole if there is no supernova,” he concluded.

Explore further: Astronomer discovers supernova in Fireworks Galaxy

More information: S. M. Adams et al. The search for failed supernovae with the Large Binocular Telescope: confirmation of a disappearing star, Monthly Notices of the Royal Astronomical Society (2017). DOI: 10.1093/mnras/stx816 , On Arxiv: https://arxiv.org/abs/1609.01283

This article and images was originally posted on [Phys.org – latest science and technology news stories] May 25, 2017 at 06:36AM

Provided by: NASA’s Goddard Space Flight Center

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