Tag: science

Cassini’s last fly-by of Dionne on Monday

2:05 pm

Dionne

On Monday August 17 Cassini will make its last close fly-by of Saturn’s moon Dionne, dipping to within 295 miles of the surface.

During the flyby, Cassini’s cameras and spectrometers will get a high-resolution peek at Dione’s north pole at a resolution of only a few feet (or meters). In addition, Cassini’s Composite Infrared Spectrometer instrument will map areas on the icy moon that have unusual thermal anomalies — those regions are especially good at trapping heat. Meanwhile, the mission’s Cosmic Dust Analyzer continues its search for dust particles emitted from Dione.

The image of Dionne above is from a June 16, 2015 fly-by, The diagonal line at the top is Saturn’s rings.

After more than a decade, Cassini’s mission is in its final stages. When completed, we will have no way for decades to get close-up images of this gas giant, its spectacular rings, or its many very different moons.

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The wild Martian terrain

10:56 am

Yardangs on Mars

This week’s image release from the high resolution camera on Mars Reconnaissance Orbiter illustrate well the wild and mysterious geology of the Martian surface. I include cropped sections from two images here, just to give you a taste. Go to the link to do your own exploring.

The image to the right is a cropped and scaled down version of the original image, so the details are not easily seen. Make sure you look at the original. The strange yardang ridges, all aligned alike, rise up out of a relatively smooth plain.

Yardangs are formed when a surface that is composed of materials of differing strengths (i.e., of both harder and softer materials) is shaped by the abrasive action of sand and dust carried by the wind. In this case, and given the proximity of the Apollonaris Patera volcanic center, we think that these wind-carved deposits are comprised of volcanic ash and pyroclastics that erupted from Apollonaris when it was last active in the not-too-distant geologic past. Over time, the softer materials (likely volcanic ash) were eroded away, leaving behind the harder materials in the form of elongated ridges that are parallel to the direction of the prevailing wind. The end result is a stunning, out-of-this-world display of yardangs, sculpted with the artistic chisel of the Martian wind.

That’s the theory, anyway. The actual geological process that formed these ridges is probably a lot more complicated.

The image below the fold illustrates the on-going surface activity on Mars.
» Read more

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Where is Pluto’s nitrogen coming from?

9:28 am

As New Horizons’ engineers download data and plan future maneuvers to fly past one of two candidate Kuiper Belt objects, the science team today outlined the background mystery of Pluto’s nitrogen.

Pluto’s atmosphere is similar to Earth’s in that it is predominantly composed of nitrogen (N). But Pluto’s atmosphere is ~98% N, while Earth’s is only ~78% N. Pluto’s atmosphere is also considerably thinner than Earth’s with ~10,000 times lower pressure at the surface.

The nitrogen in Pluto’s atmosphere (in the form of N2 gas) is actually flowing away and escaping the planet at an estimated rate of hundreds of tons per hour. We also see what looks like flowing ice on Pluto’s surface in high resolution images made by New Horizons. The water ice (H2O) that we are familiar with on Earth would be completely rigid and stiff at Pluto’s surface temperatures, but ice made out of N2 would be able to flow like a glacier. So where does all of this nitrogen come from?

They have rejected comets as a source, and have predicted that geologic activity on Pluto itself could dredge the nitrogen up from the planet’s interior. (This prediction by the way was made before the New Horizons’ flyby, which has proved it likely.)

If their theory ends up the answer, then they will also prove that Pluto is losing mass, albeit slowly. Nitrogen from within is being processed out of the interior, into the atmosphere as gas, and then into space because Pluto’s gravity is too small to hold it.

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Sudden outburst activity on Comet 67P/C-G

8:38 am

jet on Comet 67P/C-G

Cool image time! As Comet 67P/C-G approaches perihelion, Rosetta is detecting and imaging more and more activity coming from the nucleus, including a power outburst lasting less than a half hour.

In the approach to perihelion over the past few weeks, Rosetta has been witnessing growing activity from Comet 67P/Churyumov–Gerasimenko, with one dramatic outburst event proving so powerful that it even pushed away the incoming solar wind.

The comet reaches perihelion on Thursday, the moment in its 6.5-year orbit when it is closest to the Sun. In recent months, the increasing solar energy has been warming the comet’s frozen ices, turning them to gas, which pours out into space, dragging dust along with it.

The three pictures above were taken 18 minutes apart. The first shows nothing, and in the last the jet has almost completed dissipated. In the middle image, however, the jet is well defined, and data from the spacecraft indicated that it was so strong that it “had pushed away the solar wind magnetic field from around the nucleus.”

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Scientists narrow the next Mars rover candidate landing sites to 8

9:13 am

Jezero Crater

For the next Mars rover, scheduled to launch in 2020, scientists have now narrowed their candidate landing sites to eight, with Jezero Crater (pictured on the right) the favorite choice.

The top vote getter was Jezero crater, which contains a relic river delta that could have concentrated and preserved organic molecules. “The appeal is twofold,” says Bethany Ehlmann, a planetary scientist at the California Institute of Technology (Caltech) in Pasadena. “Not only is there a delta, but the rocks upstream are varied and diverse.”

The image clearly shows the scientific attraction of Jezero Crater, with an obvious meandering river canyon opening out into an obvious river delta. The crater in the delta will also give them an opportunity to do some dating research, since that crater had to have been put there after the delta was formed.

The choice however illustrates the difference in goals between scientists and future colonists. Scientists are looking for the most interesting locations for understanding the geological history of Mars. Future colonists want to find the best places to establish a home. Jezero Crater, as well as the other eight candidate sites, do not necessarily fit that settlement need. For a colonist it might be better to put a rover down on the flanks of Arsia Mons, one of Mars’ giant craters where scientists have evidence of both water-ice and caves. None of the candidate sites, however, are aimed anywhere close to this volcanic region, because scientifically it is not as interesting.

This is not to say that the candidate sites might not be good settlement sites. It is only to note that the focus of these scientists is research only. Furthermore, it is probably premature anyway to look for settlement sites. We need to know more about Mars itself.

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The bog bodies of Europe

3:37 pm

Link here. The peat bogs preserve the bodies, providing scientists a window into the past. However, the bodies exhibit one mysterious tendency: violent death.

Since the 18th century, the peat bogs of Northern Europe have yielded hundreds of human corpses dating from as far back as 8,000 B.C. Like Tollund Man, many of these so-called bog bodies are exquisitely preserved—their skin, intestines, internal organs, nails, hair, and even the contents of their stomachs and some of their clothes left in remarkable condition. Despite their great diversity—they comprise men and women, adults and children, kings and commoners—a surprising number seem to have been violently dispatched and deliberately placed in bogs, leading some experts to conclude that the bogs served as mass graves for offed outcasts and religious sacrifices. Tollund Man, for example, had evidently been hanged.

Read it all. It is a fascinating combination of history, archeology, and forensics.

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The sunspot decline continues

2:59 pm

On Monday NOAA posted its monthly update of the solar cycle, showing the Sun’s sunspot activity in July. As I have done every month since 2010, I am posting it here, below the fold, with annotations to give it context.

Sunspot counts continue to decline at a rate faster than predicted or is usual during ramp down from solar maximum. Normally the ramp down is slow and steady. This time it has so far been more precipitous. While the 2009 prediction of the solar science community (indicated by the red curve) suggests minimum will occur sometime after 2020, the actual counts suggest it will occur much sooner.

» Read more

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Curiosity looks ahead at its future travels

2:17 pm

The future terrain at Mt Sharp

Cool image time! The above image is a cropped version of a full resolution image taken by Curiosity of the terrain the rover will be traveling in the coming years.

I have also enhanced the contrast slightly to bring out the details. The terrain is rugged and very diverse, from rounded buttes to rocky outcrops.

Gravel and sand ripples fill the foreground [not shown in my cropped version above], typical of terrains that Curiosity traversed to reach Mount Sharp from its landing site. Outcrops in the midfield are of two types: dust-covered, smooth bedrock that forms the base of the mountain, and sandstone ridges that shed boulders as they erode. Rounded buttes in the distance contain sulfate minerals, perhaps indicating a change in the availability of water when they formed. Some of the layering patterns on higher levels of Mount Sharp in the background are tilted at different angles than others, evidence of complicated relationships still to be deciphered.

Traversing this rugged terrain will be a challenge but it is necessary to obtain data that will help decipher its origins. The immediate goal will be to reach the light brown terrain in the distance. In the full image, that region gently slopes upward to the left to the mountain summit, providing a route to the rover’s eventual goal.

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New Ebola vaccine 100% successful in trial

10:06 am

Using a different experimental approach aimed not only to test a new vaccine but also to stem an Ebola outbreak, scientists have found the new vaccine is 100% successful in providing exposed individuals protection from the virus.

Rather than create a complicated time-consuming trial with a control group getting a placebo — which also allows the epidemic to rage undisturbed — they focused on a different approach:

The Guinea trial — called ‘Ebola, ça suffit’ in French (‘Ebola, that’s enough’) — tested a ring vaccination design, a strategy that was borrowed from successful smallpox eradication efforts in the 1970s. After one patient contracts the disease, their close contacts are vaccinated in the hope of stemming the onward spread of the virus.

The Guinea trial included two arms: one in which adults who had been in contact with someone infected with Ebola and their subsequent contacts were vaccinated shortly after the original patient developed Ebola, and a second in which contacts instead received the vaccine three weeks later. The trial tested a vaccine called rVSV-ZEBOV, which is composed of an attenuated livestock virus engineered to produce an Ebola protein. The vaccine was developed by the Public Health Agency of Canada and then licensed to the drug companies NewLink Genetics and Merck.

Of the 2,014 people who received the vaccine immediately as part of the first arm, none developed Ebola ten days after getting the vaccine. The 10-day window allows the vaccine to summon an immune response and accounts for any pre-existing Ebola infection. (A few people in the immediate vaccination group, however, did develop the disease between 1 and 10 days after vaccination.) That compares with 16 infections among the 2,380 people in the second arm.

The findings mean that the vaccine provided 100% protection from the virus.

The results bring hope that Ebola is now a defeated virus.

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Alan Stern gives the IAU a piece of his mind

9:39 am

New Horizons’ principle investigator yesterday told the International Astronomical Union what he thinks of their definition of a planet:

“It’s bulls—,” he told Tech Insider (and said we could quote him on that).

The problem, Stern said, is that the reclassification largely stemmed from the opinions of astronomers, not planetary scientists. His beef here is that astronomers study a large variety of celestial objects and cosmic phenomena, while planetary scientists focus solely on planets, moons, and planetary systems.

“Why would you listen to an astronomer about a planet?” Stern said. He compared it to going to a podiatrist for brain surgery instead of a brain surgeon. “Even though they’re both doctors, they have different expertise,” Stern said. “You really should listen to planetary scientists that know something about this subject. When we look at an object like Pluto, we don’t know what else to call it.”

Stern’s opinion is not unique among planetary scientists. I have interviewed many, and read reports by others, which consistently say that they object strongly to the IAU’s definition. To them, if a object has enough mass to force it into a sphercial shape, it is a planet.

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Philae results published

9:32 am

Cool image time! The Philae science team yesterday published in Science a set of papers describing their results from the lander’s approach and bouncing landing on Comet 67P/C-G.

Data were obtained during the lander’s seven-hour descent to its first touchdown at the Agilkia landing site, which then triggered the start of a sequence of predefined experiments. But shortly after touchdown, it became apparent that Philae had rebounded and so a number of measurements were carried out as the lander took flight for an additional two hours some 100 m above the comet, before finally landing at Abydos.

Some 80% of the first science sequence was completed in the 64 hours following separation before Philae fell into hibernation, with the unexpected bonus that data were ultimately collected at more than one location, allowing comparisons between the touchdown sites.

The images from lander so far released show the approach to the first site, with one boulder getting larger and larger as it descends, followed by images at the final landing site, showing a fractured, uneven, and very rough surface with the lander apparently sitting sideways with one foot off the ground.

An animation of the first touchdown, created by these images, can be viewed here.

Update: A good summary of the results can be read here.

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The supernova of 1987 finally begins to fade

7:32 pm

Almost thirty years after Supernova 1987a became the first naked eye supernova since the invention of the telescope, the necklace ring of spots that the explosion’s shockwave ignited in the late 1990s are finally beginning to fade.

But now the hotspots have slowly begun to fade, Claes Fransson (Stockholm University, Sweden) and colleagues report in the June 10th Astrophysical Journal Letters. The team studied images taken by the Hubble Space Telescope from 1994 to 2014, and spectra from the Very Large Telescope spanning 2000 to 2013. Based on the rate at which the hotspots are fading, the researchers predict the glittering necklace will fade away sometime between 2020 and 2030, with the calculations favoring closer to 2020. The clumps of gas in the central ring are likely dissolving, thanks to a combination of instabilities and conduction in the hot gas surrounding the clumps. In other words, the central ring is being destroyed.

The show really isn’t over. The aftermath of a star exploding goes on for thousands of years. So to will SN1987a’s show.

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Astronomers confirm existence of Earthlike exoplanet 21 light years away

12:22 pm

Worlds without end: Astronomers have confirmed the existence of a rocky Earthlike exoplanet only 21 light years away.

HD 219134b is also the closest exoplanet to Earth to be detected transiting, or crossing in front of, its star and, therefore, perfect for extensive research. “Transiting exoplanets are worth their weight in gold because they can be extensively characterized,” said Michael Werner, the project scientist for the Spitzer mission at NASA’s Jet Propulsion Laboratory in Pasadena, California. “This exoplanet will be one of the most studied for decades to come.”

The planet has a mass 4.5 times that of Earth, and orbits its sun every three days, which means it is not likely to harbor life. Its sun also harbors three other small exoplanets, but little is known of them.

Expect a lot more news coming from HD 219134b, however. With transits every three days, astronomers are going to have a lot of opportunities to study its atmosphere and make-up.

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Counting bats on a Saturday evening

8:00 am

While most normal people spend their Saturday evenings going out to dinner followed by either a movie or a show, I spent this past Saturday doing something entirely different: counting bats!

There is a local cave here in the Tucson area that is a maternity colony for one species of bats. During the summer the females gather here to gossip and then give birth to their babies, after which they move on until next year. Because of a desire to help these bats, a few years ago the managers of the cave decided to close it during the summer months. This way humans wouldn’t be there to disturb the mothers during their labor.

The managers also decided to do regular bat counts of the bats leaving the cave each evening to feed, in order to get an estimate of the population size. To everyone’s delight they found the numbers rising year-to-year, following the summer closure. The total population of bats isn’t actually going up, but it appears that bats are finding this cave to be a good place to give birth, so more and more of them are making it their summer residence.

In the end the situation will contribute to an actual rise in population, as providing the maternity colony a safe haven will allow for more successful births and more babies.

In the past three years the bat count numbers over each summer would exhibit a typical bell curve, going up and then declining as the summer progressed, with the largest numbers ranging between 75 to 150 each night. However, last year there was one evening in which no bats left the cave. The bat biologist leading the bat count, Sandy Wolf, has theorized that this might be because the mothers are synchronizing their labor so that everyone gives birth at the same time and, because of that, on that night no one exits for feeding.. She knows that some species do this, but for this particular species such behavior has never been documented.

Anyway, she decided to find out. This has required that someone be at the entrance counting the bats at least every other evening. (In past years the counts were only done about once a week.) This has required more help, and thus Sandy has called for volunteers to do the work.

And that is how I and fellow caver Jerry Isaman ended up hiking up the hill to the cave with digital camera, infrared lights, and monitor this past Saturday.

» Read more

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Puzzling red arcs on the Saturn moon Tethys

10:44 am

Red arcs on Tethys

Baffling image time! Images taken in April 2015 by Cassini of the Saturn moon Tethys have produced the best images yet of the puzzling red arcs on the moon’s surface, first identified in 2004.

The origin of the features and their reddish color is a mystery to Cassini scientists. Possibilities being studied include ideas that the reddish material is exposed ice with chemical impurities, or the result of outgassing from inside Tethys. They could also be associated with features like fractures that are below the resolution of the available images.

Except for a few small craters on Saturn’s moon Dione, reddish-tinted features are rare on other moons of Saturn. Many reddish features do occur, however, on the geologically young surface of Jupiter’s moon Europa. “The red arcs must be geologically young because they cut across older features like impact craters, but we don’t know their age in years.” said Paul Helfenstein, a Cassini imaging scientist at Cornell University, Ithaca, New York, who helped plan the observations. “If the stain is only a thin, colored veneer on the icy soil, exposure to the space environment at Tethys’ surface might erase them on relatively short time scales.”

I could also file this under “the uncertainty of science”, as the scientists at this point haven’t the slightest idea what created these arcs.

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How Comet 67P/C-G interacts with the solar wind

9:19 am

Accumulating data from Rosetta is now giving scientists an excellent picture of how this comet interacts with the solar wind as it moves in towards its closest approach to the Sun.

They have seen that the number of water ions – molecules of water that have been stripped of one electron – accelerated away from the comet increased hugely as 67P/C-G moved between 3.6AU (about 538 million km) and 2.0AU (about 300 million km) from the Sun. Although the day-to-day acceleration is highly variable, the average 24-hour rate has increased by a factor of 10,000 during the study, which covered the period August 2014 to March 2015.

The water ions themselves originate in the coma, the atmosphere of the comet. They are placed there originally by heat from the Sun liberating the molecules from the surface ice. Once in gaseous form, the collision of extreme ultraviolet light displaces electrons from the molecules, turning them into ions. Colliding particles from the solar wind can do this as well. Once stripped of some of their electrons, the water ions can then be accelerated by the electrical properties of the solar wind.

Not all of the ions are accelerated outwards, some will happen to strike the comet’s surface. Solar wind particles will also find their way through the coma to hit home. When this happens, they cause a process called sputtering, in which they displace atoms from material on the surface – these are then ‘liberated’ into space.

There’s more at the link, including animations and simulations.

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New Pluto data released

11:54 am

Pluto

Cool image time! During today’s New Horizons’ press conference, principal investigator Alan Stern noted that only 4%-5% of the data has been recovered. They have finished first phase of download and are moving into second phase, which will be dominated by engineering and other data, not images. So, for the next couple of months they will only be able to release images once and awhile. Beginning in September images, however, they will begin downloading images at a much faster pace.

Some results from today:
» Read more

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Worlds without end

1:01 pm

Last week’s fly-by of Pluto by New Horizons illustrated forcefully once again the power of exploration on the human mind, and how that exploration always carries surprises that delight and invigorate us.

First of all, the images from that fly-by demonstrated clearly that the decision by the International Astronomical Union (IAU) to declare Pluto a non-planet was very much premature. Even project scientist Alan Stern himself enthusiastically noted at the start of Friday press conference that Pluto-Charon was a “double planet system”.

The IAU definition itself was faulty and difficult to apply. The clause that required a planet to have “cleared the neighborhood around its orbit” made little sense in the real universe, as even the Earth has not successfully cleared its orbit after several billion years. Was the IAU suggesting the Earth was not a planet?

New Horizons’s discovery last week that even a small object like Pluto, orbiting the Sun on its own with no gas giant nearby to provide tidal heating, can still exhibit significant and on-going geological activity, shows that our understanding of what defines a planet is at this time quite limited. We simply don’t know enough about planetary evolution and formation to definitively define the term. Nor do we have enough knowledge to determine if Pluto falls into that category, though the data strongly suggests that it does.

Are planets made up of only gas giants, rocky terrestrial planets like the Earth, and dwarf planets like Ceres and Pluto? Or are there numerous other as yet unknown categories?
» Read more

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Astronomers confirm Kepler discovery of near twin of Earth

10:08 am

Worlds without end! In the release today of another set of Kepler data, astronomers have announced the discovery in that dataset of a new twin of Earth.

The newly discovered Kepler-452b is the smallest planet to date discovered orbiting in the habitable zone — the area around a star where liquid water could pool on the surface of an orbiting planet — of a G2-type star, like our sun. The confirmation of Kepler-452b brings the total number of confirmed planets to 1,030. …

Kepler-452b is 60 percent larger in diameter than Earth and is considered a super-Earth-size planet. While its mass and composition are not yet determined, previous research suggests that planets the size of Kepler-452b have a good chance of being rocky. While Kepler-452b is larger than Earth, its 385-day orbit is only 5 percent longer. The planet is 5 percent farther from its parent star Kepler-452 than Earth is from the Sun. Kepler-452 is 6 billion years old, 1.5 billion years older than our sun, has the same temperature, and is 20 percent brighter and has a diameter 10 percent larger.

While this exoplanet is certainly not identical to Earth, it is close enough that the possibility of alien life — really alien life — could very likely exist upon it.

The dataset also included 11 other Earth twin candidate exoplanets that still need to be confirmed.

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Haze spotted over Ceres’ double bright spot

9:15 am

Dawn, in orbit around Ceres, has detected a haze above the dwarf planet’s double bright spot, suggesting that the tiny asteroid/planet is still geologically active.

Haze on Ceres would be the first ever observed directly in the asteroid belt. In 2014, researchers using the European Space Agency’s Herschel Space Observatory reported seeing water vapour spraying off Ceres, which suggested that it was geologically active1. At least one-quarter of Ceres’s mass is water, a much greater proportion than seen in most asteroids.

Bright spots pepper Ceres’s surface, but the haze has so far been seen in only one location — a crater named Occator, which has a large bright area at its centre and several smaller spots nearby. Mission scientists have been trying to work out whether the bright spots are made of ice, evaporated salts or other minerals, or something else entirely.

Some team members had been leaning towards the salt explanation, but the discovery of haze suggests the presence of sublimating ice. “At noontime, if you look at a glancing angle, you can see what seems to be haze,” Russell says. “It comes back in a regular pattern.” The haze covers about half of the crater and stops at the rim.

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Mountains and craters on Pluto?

9:09 am

The edge of Tombaugh Regio

Cool image time! Even as they download new images for a press conference on Friday, the New Horizons’ science team has released a new close-up of Tombaugh Regio, showing both a new mountain range within it as well as its sharply defined western contact with the dark whale feature, which now appears to be heavily cratered and old.

“There is a pronounced difference in texture between the younger, frozen plains to the east and the dark, heavily-cratered terrain to the west,” said Jeff Moore, leader of the New Horizons Geology, Geophysics and Imaging Team (GGI) at NASA’s Ames Research Center in Moffett Field, California. “There’s a complex interaction going on between the bright and the dark materials that we’re still trying to understand.” While Sputnik Planum is believed to be relatively young in geological terms – perhaps less than 100 million years old — the darker region probably dates back billions of years. Moore notes that the bright, sediment-like material appears to be filling in old craters (for example, the bright circular feature to the lower left of center).

Make sure you click through to see the full resolution image. It is quite astonishing. They have also released a new image each of two of Pluto’s moons.

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Iran’s parliament questioning Iran nuclear deal

11:24 am

Democracy in action! Iran’s parliament is likely to demand changes to Iran deal before voting for its approval.

The ironies here are tragic. While their parliament stands up for its constitutional rights, our Congress, run by Republicans, has ceded its power to the President, with the Senate giving up its constitutional right to only approve treaties with a two-third majority. Instead, they got down on their knees and handed Obama the power to make this very bad treaty without their full consent. What idiots.

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Internet tycoon commits $100 million to alien life search

9:16 am

Russian internet entrepreneur Yuri Milner has given SETI $100 million for a ten year project to accelerate their effort to search for evidence of extraterrestrial life.

Understanding why SETI needs private funding is important:

SETI has been going on since 1960, when radio telescopes became sensitive enough to detect signals from another planet if it was broadcasting signals similar to those which our civilization does. Researchers developed devices that could monitor millions of frequencies at once for any signal that looked at all different from that produced by astronomical objects or the natural background. At first funded by universities and NASA, public funding for SETI was axed by Congress in the early 1990s. Since then, the nonprofit SETI League has received funding of a few million dollars a year from private donors.

Congress correctly cut the funds because it isn’t really the business of the federal government to search for alien life. Some taxpayers really don’t want their money used for that purpose, and they should have the right to say no. Instead, Congress essentially told SETI to do it right: Get private funding from people who want the research done. The work will be done more efficiently for less, and no one will be required to contribute who doesn’t want to.

Milner’s contribution now is the biggest donation yet, and suggests that interest in this research is building culturally.

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