Tag: science

Pluto’s mountains are white-capped but with methane not ice

6:23 pm

Pluto's white-capped mountains
Pluto’s mountains, capped with methane snow.
Click for full figure.

Scientists now theorize that the white-capped mountains first photographed by New Horizons during its 2015 fly-by of Pluto are capped not with ice but with methane snow, as part of that planet’s methane gas-ice cycle.

The image to the right, from their paper, shows these white-capped mountains on Pluto.

The exact composition of this frost on Pluto was unclear. While researchers identified methane, it was unknown whether it is pure frozen methane, frozen methane diluted with frozen nitrogen or a mix of both. The uncertainty about the frost’s composition made it unclear how it might have formed.

To help solve these mysteries, scientists in this new study examined high-resolution data from New Horizons, focusing on the composition of the frost at high altitudes. This new analysis revealed that the snowcap frost “is almost pure methane ice, with traces of nitrogen ice,” Bertrand said.

The researchers also developed high-resolution computer simulations of Pluto’s climate. They focused on how methane circulates around the dwarf planet. [emphasis mine]

Though their simulations of the methane cycle that produces the caps are reasonable, I purposely highlight the fact that this is what they are, and as such must be treated with great skepticism. We might now know the composition of these snowcaps, but our overall knowledge of Pluto remains to limited to trust blindly any computer model.

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Lava cones, fissures, and channels from Olympus Mons

9:11 am

A lava cone, fissure, and channel on Mars
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken on June 29, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). In this one spot we see three obvious volcanic features, all however formed by different processes.

The location of this image is west of Olympus Mons. It sits on the vast lava plain that was laid down by that volcano, the largest in the solar system.

In order of likely occurrence, the cone probably came first. It likely indicates a past eruption coming up from below to create a small volcano.

The shallow meandering channel that sweeps around it to the north and east probably marks a later lava flow coming down from Olympus Mons.

The deeper straight fissure to the south probably came last. It is a graben, a crack caused by the uplift of the entire surface because of pressure from a magma chamber below, causing cracks to form as the surface is stretched.

Three different volcanic events, each probably taking thousands of years, with maybe thousands to millions of years between them. The context map below adds weight to the scale of time and size represented by this one Martian photo.
» Read more

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Juno science team proposes fly-bys of Jupiter’s moons

8:30 am

The Juno science team has proposed doing fly-bys of three of Jupiter’s moons, should NASA extend the mission beyond ’21.

Juno’s five-year primary mission phase ends in July 2021, and mission managers have proposed an extension that would continue operations until September 2025. The spacecraft’s additional orbits around Jupiter will bring Juno closer to the planet’s moons, allowing for a more diversified set of scientific targets.

…The moon flybys would begin in mid-2021 with an encounter with Ganymede, Jupiter’s largest moon, at a distance of roughly 600 miles (1,000 kilometers), according to Bolton.

After a series of distant passes, Juno would swoop just 200 miles (320 kilometers) above Europa in late 2022 for a high-speed flyby. Only NASA’s Galileo spacecraft, which ended its mission in 2003, has come closer to Europa.

There are two encounters with Jupiter’s volcanic moon Io planned in 2024 at distances of about 900 miles (1,500 kilometers), according to the flight plan presented by Bolton last month.

The extended mission would also allow scientists to get a better look at Jupiter’s north pole.

NASA will decide on the extension by the end of the year. From a cost and scientific perspective, it makes perfect sense to extend this mission for as long as possible. Compared to launching a new mission, extending an active one is far cheaper. It is also already in place.

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A massive Martian glacier that looks just like a glacier on Earth

2:06 pm

Massive glacier on Mars
Click for full image.

If you ever had any doubt about the existence of glaciers on Mars, today’s cool image should ease those doubts. The photo to the right, taken on August 27, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and rotated, cropped, and reduced to post here, shows many features that are appear identical to features found on typical massive glaciers on Earth.

Downhill is to the northwest. The many parallel grooves or fractures running along the length of the glacier resemble what are seen in many similar Earth glaciers. Some of these fractures are caused by the glaciers slow drift downward, with different sections moving at slightly different rates, thus causing a separation along the flow. Hence the parallel fractures.

These fractures also show evidence of some erosion. Because these Martian glaciers are no longer getting more snowfall, they are no longer growing. However, if the thin layer of dust and debris that protects the ice gets blown off or removed by motion, the ice is exposed and can then sublimate into gas so that the glacier erodes.

On the flow’s edges the darker parallel lines also resemble features seen on Earth, showing the exposed layers of the glacier’s past levels. The same thing can be seen on either side of the canyon’s walls.

The wide smooth section near the center of the parallel lines could very well be an impact crater that landed on this glacier sometime in the far past, and has since been distorted in shape as the glacier flowed downward.

If you still have doubts, the context image below, taken by MRO’s wide angle context camera, should help further allay those doubts.
» Read more

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Astronomers watch star’s destruction as supermassive black hole eats it

10:27 am

Astronomers, using a number of ground-based and orbiting telescopes, successfully observed a star’s destruction as it was ripped apart and eaten by a supermassive black hole at the center of a galaxy 215 million light years away.

The team carried out observations of AT2019qiz, located in a spiral galaxy in the constellation of Eridanus, over a 6-month period as the flare grew in luminosity and then faded away. “Several sky surveys discovered emission from the new tidal disruption event very quickly after the star was ripped apart,” says Wevers. “We immediately pointed a suite of ground-based and space telescopes in that direction to see how the light was produced.”

Multiple observations of the event were taken over the following months with facilities that included X-shooter and EFOSC2, powerful instruments on ESO’s VLT and ESO’s NTT, which are situated in Chile. The prompt and extensive observations in ultraviolet, optical, X-ray and radio light revealed, for the first time, a direct connection between the material flowing out from the star and the bright flare emitted as it is devoured by the black hole. “The observations showed that the star had roughly the same mass as our own Sun, and that it lost about half of that to the monster black hole, which is over a million times more massive,” says Nicholl, who is also a visiting researcher at the University of Edinburgh.

Astronomers have seen similar events previously, but never so close and never so early in the event.

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CDC study: Masks do nothing to stop COVID-19 infection

10:52 pm

A new CDC study shows that masks appear to have zero effect in stopping the spread of the COVID-19 virus.

An underreported, recently-published CDC study adds to the pile of evidence that cloth masks or other forms of mandated face coverings only contribute negatives to our COVID-19 problem. The study also displays — despite the constant accusations of widespread misbehavior from public health officials — that Americans are adhering to mask wearing, but mask wearing is not doing us any good.

The CDC study, which surveyed symptomatic COVID-19 patients, has found that 70.6% of respondents reported “always” wearing a mask, while an additional 14.4% say they “often” wear a mask. That means a whopping 85% of infected COVID-19 patients reported habitual mask wearing. Only 3.9% of those infected said they “never” wear a face covering.

The graph below from the study is damning. It shows that wearing a mask made no difference between those who got the disease (left column) and those in the control group.

CDC study graph: masks made no difference.

In either case, the number of cases remained the same no matter how much you wore the mask.

I suspect however that a larger study will find more infections among full-time mask wearers, especially if that study delineates between those medical professionals who are trained to wear the mask properly and with care, keeping it anti-septic, and the general public who fingers their mask continually and then sticks it in their pocket between uses.

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A lunar landslide

10:03 am

Landslide on the Moon
Click for full image.

Cool image time! The image to the right was posted by the Lunar Reconnaissance Orbiter (LRO) science team on October 9, 2020, and shows a spectacular landslide almost a mile and a half long that had occurred on the interior rim of a crater on the Moon.

The top of the rim is on the left, with the landslide breaking out onto the floor of the crater on the right.

The walls of Kepler crater (30 kilometer diameter) exhibit numerous landslides. In this example, a landslide of dark material begins about 100 meters below the rim from a narrow box canyon. The box canyon is about 50 meters wide and 300 meters long. Overall, the slide is extends some 2300 meters (from the end of the canyon to its base). The base of the slide is on a fault block that lies some 1800 meters below the rim. The wall slope is about 33 degrees.

This slide is actually composed of a series of narrow landslides 20-30 meters wide. Along most of the slope, the individual slides overrun each other forming a band of debris up to about 180 meters wide. At the base of the slope, the individual slides can be recognized as they move apart forming a fan of material. A few individual isolated slides also occur adjacent to the main mass. The overlapping nature of these small slides indicate that the overall feature may have formed over a period of time, rather than all at once.

From above and at this resolution, the landslide looks almost like frozen flowing liquid. It allso looks like it began with a scattering of boulders breaking free at the top all at once that quickly consolidated into a single massive avalanche.

At the link you can zoom in or out to look at the entire image, at full resolution.

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A mile-long trail of human footprints about 12,000 years old

9:41 am

Scientists have found in New Mexico a mile-long trail of human footprints from about 12,000 years ago that was probably left by a woman and toddler.

Even more interesting, the tracks show that the woman (or male adolescent) retraced her route, without the child.

Unlike many other known footprint trackways, this one is remarkable for its length – over at least 1.5km [almost a mile] – and straightness. This individual did not deviate from their course. But what is even more remarkable is that they followed their own trackway home again a few hours later.

Each track tells a story: a slip here, a stretch there to avoid a puddle. The ground was wet and slick with mud and they were walking at speed, which would have been exhausting. We estimate that they were walking at over 1.7 metres per second – a comfortable walking speed is about 1.2 to 1.5 metres per second on a flat dry surface. The tracks are quite small and were most likely made by a woman, or possibly an adolescent male.

At several places on the outward journey there are a series of small child tracks, made as the carrier set a child down perhaps to adjust them from hip to hip, or for a moment of rest. Judging by the size of the child tracks, they were made by a toddler maybe around two years old or slightly younger. The child was carried outward, but not on the return.

There is also evidence of a mammoth and sloth crossed the tracks in-between the outward and return journey, with the sloth apparently sensing the human tracks or presence.

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More Martian pits!

2:28 pm

Pit #1
Click for full image.

Pit #2
Click for full image.

Though the number of new pictures showing pits and possible caves from the high resolution camera on Mars Reconnaissance Orbiter (MRO) has significantly tailed off in the past year, as I noted in my previous post on Martian pits in September, the pictures are still rolling in. This post will highlight five new photos and the pits therein.

The first two, on the right, are both located on the southern flanks of the giant volcano Arsia Mons, where many such pits are found. They were taken respectively on August 16, 2020 and August 27, 2020. The first was a captioned image from MRO’s science team:

In this image, the ceiling of the lava tube collapsed in one spot and made this pit crater. The pit is about 50 meters (150 feet) across, so it’s likely that the underground tube is also at least this big (much bigger than similar caves on the Earth). HiRISE can’t see inside these steep pits because it’s always late afternoon when we pass overhead and the inside is shadowed at that time of day.

What I find most interesting about both images is that the skylights do not occur where you’d expect. In image #1, the meandering rill that suggests an underground lava tube is about 1,000 feet south of the pit. The pit itself seems unrelated to that rill. In image #2, the surface shows no obvious evidence of an underground tube matching the three aligned pits. There is the hint of a narrow depression along the alignment of the three pits, but this could just as easily be evidence of wind-blown dust along that alignment.

In the full image all three pits appear to sit inside a very wide and very shallow northwest-to-southwest depression, but this is hardly certain, and regardless the three pits align in a different direction.

The overview map below provides some context.
» Read more

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Flying over Jupiter

11:02 am

Cool movie time! Using images produced by Juno in orbit around Jupiter, citizen scientist Kevin Gill has produced a very nice movie of the spacecraft’s 27th fly-by on June 2, 2020.

During the closest approach of this pass, the Juno spacecraft came within approximately 2,100 miles (3,400 kilometers) of Jupiter’s cloud tops. At that point, Jupiter’s powerful gravity accelerated the spacecraft to tremendous speed — about 130,000 mph (209,000 kilometers per hour) relative to the planet.

I have embedded the movie below the fold. The choice of a piece of music by Vangellis might seem hokey, but I think in this case it works very nicely. I also was impressed with the addition of some 3D depth near the movie’s beginning.
» Read more

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A typical mid-latitude Martian crater with glacial features

2:22 pm

Typical mid-latitude Martian crater with glacial fill
Click for full image.

Cool image time! The crater on the right, the image cropped and reduced to post here, is a great example of many craters scientists have found in the mid-latitudes on Mars containing a variety of features that suggest buried glaciers. In this case we are looking at what they have dubbed a concentric crater fill, material that resembles glacial material that fills the crater’s interior and floor, and appears often to erode in a series of rings. You can see another example here.

The photo was taken on June 29, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The crater itself is located in a region of chaos terrain dubbed Nilosyrtis Mensae, located in the transition zone between the cratered southern highlands and the lowland northern plains.

Nilosyrtis Mensae is part of a region of Mars I call glacier country. When you include the mensae regions Protonilus and Deuteronilus to the west, this transition zone of random mesas, knobs, and criss-crossing canyons stretches about 2,000 miles. The context map below focuses in on Nilosyrtis Mensae, where this crater is located.
» Read more

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Radio astronomers claim negative impact from satellite constellations

10:35 am

Put them on the Moon! Radio astronomers have released a paper claiming that the coming large communication satellite constellations, such as Starlink and OneWeb, will seriously impact observations with the Square Kilometer Array (SKA) of radio telescopes being built in the remote western outback of Australia.

Saturation of the instruments: very strong interfering signals can saturate the receiver systems and thereby drown out all other signals seen by the Band 5b receivers. As a consequence, all data in that frequency band would be lost, rendering these receivers useless for a portion of the time. For the first phase of the constellation deployments (about 6,400 satellites in total), saturation is predicted to occur for a few percent of the time assuming there is no direct illumination of the dishes by the satellites. For significantly larger constellation sizes (up to more than 100,000 satellites), saturation would be essentially continuous without significant mitigation measures implemented by the satellite operators.

Based on this conclusion, the astronomers estimate that for observations in this particular band they will need to look about 70% longer to get the same data, thereby cutting the number of observations by about half.

The astronomers propose this solution:

One of these mitigation techniques is for the satellite transmitters not to point their beams near the SKAO dishes. SKAO would require operators to steer their satellites’ beams away from the telescope site, a measure which would require a simple software modification with no repercussion on the constellation’s deployment, positioning or hardware. While a cost-effective implementation of this solution does depend on the hardware and software deployed on the satellites, operators already use this technique to comply with international regulations when their satellites cross the path between geostationary satellites in higher orbit and their receiving ground stations, for example to avoid affecting telecommunications and TV transmissions.

This mitigation could reduce the impact on the SKA by a factor of 10 over that noted previously and result in a 7% increase of integration time for SKA observations within the satellite transmission range 4. While any loss of sensitivity is regrettable, SKAO recognises the need for compromise between the competing scientific and commercial drivers.

The solution seems reasonable, but in truth it is only a temporary one. The permanent and smart solution for the astronomical community is to move their telescopes, in all wavelengths, off the Earth. For radio astronomy the far side of the Moon would be ideal.

And with SpaceX now developing a reusable big rocket, Starship, to put such payloads in orbit at low cost, the astronomers need to start thinking about taking advantage of this engineering. The situation for ground-based astronomer will only get worse.

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