Tag: science

Akatsuki to finally begin studying Venus

8:46 am

After a five year delay because its initial attempt to enter Venus orbit failed, the Japanese probe Akatsuki is finally about to begin science operations.

Its present orbit is less than ideal, passing 440,000km from the planet at its farthest point. That is roughly five times greater than initially planned and means the orbit time is now nine days. The change in orbit has affected the probe’s observation plan. Of its seven planned missions, Akatsuki will be able to complete only one: taking serial images of clouds. Unfortunately, the probe’s five cameras, each capturing images in different wavelengths, including infrared and ultraviolet, will not be able to provide the same resolution at this greater distance. Observing volcanic eruptions on the Venusian surface may also be difficult.

There is an upside to the situation, however. Takeshi Imamura, an associate professor at JAXA’s Institute of Space and Astronautical Science, says the longer orbital period means the probe will be able to collect longer continuous stretches of data.

Considering everything, it is magnificent that Akatsuki will be able to do any science at Venus at all.

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Pinpointing Curiosity’s location in Gale Crater

3:07 pm

Curiosity's traverse

The Curiosity science team recently released a new Mars Reconnaissance Orbiter image, showing Curiosity’s overall route since its landing on Mars in August 2012. I have posted a reduced version on the right.

Similarly, on the Curiosity website you can view this more detailed map of its traverse route. This map is updated regularly as Curiosity continues its climb up Mount Sharp.

Neither of these maps is to me very satisfying or useful, however. Neither shows the overall location of Curiosity within Gale Crater. Nor do they give one a sense of how far it is has come on its climb up the mountain. In fact, it is very unclear how close the rover actually is to the peak from either image.

Thus, I decided to do a little research to get some better context of Curiosity’s position and its overall journey.
» Read more

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Mathematicians discover pattern in prime numbers

9:18 am

The uncertainty of science: Mathematicians have discovered that, among the first billion prime numbers, there is a peculiar uneven distribution that is not random to the last digit of each prime.

[I]f the sequence were truly random, then a prime with 1 as its last digit should be followed by another prime ending in 1 one-quarter of the time. That’s because after the number 5, there are only four possibilities — 1, 3, 7 and 9 — for prime last digits. And these are, on average, equally represented among all primes, according to a theorem proved around the end of the nineteenth century, one of the results that underpin much of our understanding of the distribution of prime numbers. (Another is the prime number theorem, which quantifies how much rarer the primes become as numbers get larger.)

Instead, Lemke Oliver and Soundararajan saw that in the first billion primes, a 1 is followed by a 1 about 18% of the time, by a 3 or a 7 each 30% of the time, and by a 9 22% of the time. They found similar results when they started with primes that ended in 3, 7 or 9: variation, but with repeated last digits the least common. The bias persists but slowly decreases as numbers get larger.

As the article notes, this pattern does not appear to have any practical use, though it definitely fascinates everyone who hears about.

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Good HDL cholesterol might not be so good

8:55 am

The uncertainty of science: New research now suggests an explanation for why in some cases having a high level of the supposedly good HDL cholesterol is not a good thing.

They think it is genetic, and that some people are missing the genes that help the HDL work to clean cholesterol out of the body. It is important however to recognize the uncertainties here. They still do not understand very well how this all works.

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Rosetta detects magnetic-free bubble around comet

8:34 am

Scientists using Rosetta have finally detected the expected bubble or region surrounding Comet 67P/C-G where there is no magnetic field and the Sun’s solar wind does not enter.

The bubble is caused by the material being ejected from the comet. Scientists had detected the same thing around Halley’s Comet back in 1986, but it turns out the bubble around Comet 67P/C-G is larger than expected based on those previous measurements, and also fluctuates in size more than predicted.

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ExoMars ready for launch

2:07 am

The European ExoMars Mars orbiter and lander mission, set for launch on March 14, is assembled on its Proton rocket and is ready for launch.

This European project was originally going to be in partnership with NASA, but the Obama administration pulled out of the deal. The Russians then offered to come in and provide a rocket for the mission.

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Monthly Solar Cycle update

11:07 am

NOAA released on Monday its monthly update of the solar cycle, showing the Sun’s sunspot activity in February. I am once again posting it here on Behind the Black, as I have done monthly since 2010.

February 2016 Solar Cycle graph

The graph above has been modified to show the predictions of the solar science community. The green curves show the community’s two original predictions from April 2007, with half the scientists predicting a very strong maximum and half predicting a weak one. The red curve is their revised May 2009 prediction.

The change in this month’s graph is so small that you will have to look real close to see it. Essentially, the February sunspot activity dropped only a tiny amount from January’s numbers, though it did drop. As such the decline from solar maximum continues to track perfectly the decline predicted by the low prediction of the 2007 predictions. This prediction success should not be taken very seriously, however, since that same prediction expected the solar maximum to begin two years earlier than it actually did.

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Want to discover gravitational waves? You can!

9:04 am

The citizen science project, Einstein@home, will begin providing its participants data from the upgraded LIGO gravitational wave detector beginning March 9.

Rather than looking for dramatic sources of gravitational waves, such as the black-hole merger that LIGO detected on 14 September, Einstein@home looks for quieter, slow-burn signals that might be emitted by fast-spinning objects such as some neutron stars. These remnants of supernova explosions are some of the least well understood objects in astrophysics: such searches could help to reveal their nature.

Because they produce a weaker signal than mergers, rotating sources require more computational power to detect. This makes them well-suited to a distributed search. “Einstein@home is used for the deepest searches, the ones that are computationally most demanding,” Papa says. The hope is to extract the weak signals from the background noise by observing for long stretches of time. “The beauty of a continuous signal is that the signal is always there,” she says.

To participate all you have to do is let their software become your screensaver, doing its work whenever you walk away from your computer.

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NASA reschedules rather than cancels InSight

8:29 am

Forced to delay its launch because its primary instrument, built by the French, would not be ready for its 2016 launch, NASA has decided to go on with the InSight Mars mission, rescheduling it for a May 2018 launch, rather than cancelling it outright.

The seismometer, built by the French space agency CNES, will be repaired in time to make the 2018 launch window, said Jim Green, the head of NASA’s planetary sciences division in Washington DC. “That’s terrific news,” he told a planetary sciences advisory panel on 9 March. The Jet Propulsion Laboratory in Pasadena, California, will assume responsibility for building a new vacuum enclosure for the seismometer.

The last sentence above suggests that NASA has decided to take certain responsibilities from the French to make sure they get done right. It also means that the cost will be born by the NASA’s planetary program, cutting into other possible future missions.

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Ceres’s big mountain

10:26 pm

Ahuna Mons on Ceres

The Dawn science team has released an oblique angle image of Ceres’s big mountain, Ahuna Mons. I have cropped and reduced it above to show it here.

Despite looking almost toylike in this image, the mountain is quite monstrous, especially considering Ceres’s relatively small size.

This mountain is about 3 miles (5 kilometers) high on its steepest side. Its average overall height is 2.5 miles (4 kilometers). These figures are slightly lower than what scientists estimated from Dawn’s higher orbits because researchers now have a better sense of Ceres’ topography.

Consider: Mount Everest is not quite six miles high, on a planet with a diameter about 7926 miles across. Ceres however is only about 600 miles across at its widest, which means a 3 mile high mountain is 0.5% of Ceres’s entire width! Such a thing could only occur on such a small body, whose gravity is not quite great enough to force things into a completely spherical shape. It is for this reason it could be argued that Ceres doesn’t qualify as a dwarf planet, but would be better labeled a giant asteroid.

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Dawn’s chief engineer reviews the mission

8:45 am

In a long and very detailed post, the chief engineer and mission director of Dawn gives us a very detailed update on the successful state of the spacecraft’s mission.

Not only does he describe what has been gathered at Ceres since the spacecraft arrived a year ago, he gives us this crucial information about the state of this paradigm-shattering ion engine spacecraft, the first to travel to two different objects in the solar system:

Dawn has faced many challenges in its unique voyage in the forbidding depths of space, but it has surmounted all of them. It has even overcome the dire threat posed by the loss of two reaction wheels (the second failure occurring in orbit around Vesta 3.5 years and 1.3 billion miles, or 2.0 billion kilometers, ago). With only two operable reaction wheels (and those no longer trustworthy), the ship’s remaining lifetime is very limited.

A year ago, the team couldn’t count on Dawn even having enough hydrazine to last beyond next month. But the creative methods of conserving that precious resource have proved to be quite efficacious, and the reliable explorer still has enough hydrazine to continue to return bonus data for a while longer. Now it seems highly likely that the spacecraft will keep functioning through the scheduled end of its primary mission on June 30, 2016.

NASA may choose to continue the mission even after that. Such decisions are difficult, as there is literally an entire universe full of interesting subjects to study, but resources are more limited. In any case, even if NASA extended the mission, and even if the two wheels operated without faltering, and even if the intensive campaign of investigating Ceres executed flawlessly, losing not an ounce (or even a gram) of hydrazine to the kinds of glitches that can occur in such a complex undertaking, the hydrazine would be exhausted early in 2017. Clearly an earlier termination remains quite possible.

Dawn has proven the value of ion engines. I would expect to see them used many more times in the future, especially missions heading to low gravity environments.

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Clouds on Pluto?

8:05 pm

A report from New Scientist today claims that the New Horizons science team has possibly seen individual clouds in some images.

Grundy had spotted features in the haze on the edge – or “limb” – of Pluto that seemed to stand out from the distinct layers. But more intriguingly, he had also seen a bright feature crossing different parts of the landscape, suggesting it was hovering above. The email kicked off a discussion as to whether the clouds were real, because it was difficult to see whether they cast shadows on the ground. The team also deliberated over the exact distinction between clouds and hazes. “One way to think of it is that clouds are discrete features, hazes widespread,” wrote Alan Stern, who heads up the New Horizons mission.

There has been no public mention of the clouds, suggesting that the team isn’t sure about the detection.

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Getting higher on Mount Sharp

9:03 am

Looking across Gale Crater

Cool image time! The above image, cropped and reduced slightly for presentation here, was taken by one of Curiosity’s navigation cameras on March 2. Though the science team has not captioned it, I think it is looking down from the heights that Curiosity has climbed and across the plains of Gale Crater to its rim in the far distance. The image itself appears to have been taken after the rover spent several days climbing up to what they have dubbed Naukluft Plateau.

Be sure to check out the full resolution image that can be found here.

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Methane ice on Pluto’s mountain peaks

8:34 am

New images from New Horizons of the dark Cthulhu region have revealed white-capped mountain peaks, thought to be methane ice.

Scientists think this bright material could be predominantly methane that has condensed as ice onto the peaks from Pluto’s atmosphere. “That this material coats only the upper slopes of the peaks suggests methane ice may act like water in Earth’s atmosphere, condensing as frost at high altitude,” said John Stansberry, a New Horizons science team member from Space Telescope Science Institute, Baltimore, Maryland.

We as humans are attracted to features on other worlds that remind us of Earth, mainly because this allows us to quickly understand what we are seeing. It is important however to remind ourselves continually that Pluto is not Earth, and is in fact a very alien place. Many things we think we recognize are really very different than what we assume. For example, the methane ice here is coating mountains made of water ice that is as stable as granite in Pluto’s super cold environment.

One more thing: It appears that at this point, seven months after New Horizons flew past Pluto, they have still only downloaded less than half the data obtained. This is not a problem, as this is how things were planned, but it does mean that there are likely many more discoveries yet for us to see.

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Hubble finds galaxy with record-breaking redshift

4:01 pm

The uncertainty of science: Using the Hubble Space Telescope astronomers have discovered a galaxy with the largest redshift ever measured, 11.1, making it the most distant object so far measured and only about 400 million years after the Big Bang..

The uncertainty is that all theories have said that this galaxy was not supposed to exist at that time.

However, the discovery also raises many new questions as the existence of such a bright and large galaxy is not predicted by theory. “It’s amazing that a galaxy so massive existed only 200 million to 300 million years after the very first stars started to form. It takes really fast growth, producing stars at a huge rate, to have formed a galaxy that is a billion solar masses so soon,” explains Garth Illingworth of the University of California, Santa Cruz.

Marijn Franx, a member of the team from the University of Leiden highlights: “The discovery of GN-z11 was a great surprise to us, as our earlier work had suggested that such bright galaxies should not exist so early in the Universe.” His colleague Ivo Labbe adds: “The discovery of GN-z11 showed us that our knowledge about the early Universe is still very restricted. How GN-z11 was created remains somewhat of a mystery for now.”

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Titan’s changing shorelines

8:53 am

Shoreline changes on Titan

Cool image time! Using radar images taken during the past decade by Cassini scientists have discovered changes taking place along the shorelines of Titan’s hydrocarbon seas.

Analysis by Cassini scientists indicates that the bright features, informally known as the “magic island,” are a phenomenon that changes over time. They conclude that the brightening is due to either waves, solids at or beneath the surface or bubbles, with waves thought to be the most likely explanation. They think tides, sea level and seafloor changes are unlikely to be responsible for the brightening.

The images in the column at left show the same region of Ligeia Mare as seen by Cassini’s radar during flybys in (from top to bottom) 2007, 2013, 2014 and 2015.

These shoreline changes are not the only ones spotted by Cassini. However, because these are radar images, not visual, there are many uncertainties about what causes the changes, which is why they list several possibilities. For example, with radar, a simple roughness on the surface (such as waves) could cause a brightening.

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