Tag: science

Sharp Martian ridges sticking up from the dust

10:35 am

Sharp ridges sticking up from Martian dust
Click for full image.

Today’s cool image brings us back to the region of Mars where the rover Opportunity journeyed. Taken on June 25, 2020 by the high resolution camera on Mars Reconnaissance orbiter (MRO), the photo to the right, cropped and reduced to post here, focuses on some sharp but low ridges that appear to stick up out of the Martian dust, hinting that they are the tops of some larger feature buried over the eons and only now revealed partly by recent erosion. I estimate that their height is roughly one to two hundred feet or so.

This image is in Arabia Terra, the widest and largest transitional zone region between the northern lowland plains and the southern cratered highlands. It is also only about 200 miles north of where Opportunity landed, and about 230 miles from where it died after almost fifteen years of operation, on the west rim of Endeavour Crater. The overview map below gives the context.
» Read more

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“We quarantined the healthy, and we exposed the sick.”

9:30 am

According to Jay Bhattacharya, director of both the Program on Medical Outcomes and the Center on the Demography and Economics of Health and Aging at Stanford University, the decisions made by most governments during the past six months in reaction to the Wuhan virus made no sense, and actually acted to worsen the epidemic.

“We essentially, in effect, exposed people who were at high risk in nursing homes, in assisted care facilities, elderly populations,” Bhattacharya said. “We essentially, in the early days of the epidemic, did the inverse of the right policy.”

“We quarantined the healthy, and we exposed the sick,” he added.

The professor noted that the World Health Organization, early on in the pandemic, suggested that the death rate for the disease might be as high as 3.4%, significantly higher than that of seasonal influenza. Revised estimates have put that rate as low as 0.26%, though some studies have put it closer to 0.5%. [emphasis mine]

The mortality rate for the flu is generally estimated at about 0.1%, so the Wuhan virus is higher, but really not by much. Moreover, these new estimates are much closer to what could have been gleaned from the early data, data that the WHO and many other government health officials ignored in favor of unreliable models. More important however is that, when compared to the flu, the data today suggests that COVID-19 is less dangerous to the healthy population, and a greater risk to the elderly sick, which once again shows that quarantining the healthy population (the lock downs) makes no sense. It only slows the arrival of herd immunity, giving the virus more time to reach the vulnerable population.

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The mystery of rust on the Moon

8:40 am

Link here. The data shows that there is rust on the Moon, in an environment lacking oxygen and water that should make it impossible for it to form.

Yet the rust is there, in the form of hematite, and in fact the data from India’s first lunar orbiter, Chandrayaan-1, has found that the Moon’s nearside has much more of it. To explain how it got there the scientists have come up with a complex hypothesis, first requiring the Moon to be shielded from the Sun’s solar wind by the Earth’s magnetic field for part of its orbit, then having that magnet field transport oxygen from the Earth’s upper atmosphere to the Moon.

This oxygen then reacts with the tiny amount of water that some scientists believe Chandrayaan-1 detected scattered in the Moon’s regolith, the equivalent of its topsoil. The result, according to this hypothesis, is that over time that oxygen and water reacted with the surface iron on the Moon’s nearside, facing the Earth, causing it to rust.

The explanation is elegant, and fits the known facts (though the presence of that water in the lunar regolith remains unconfirmed). It is also complex, which should raise doubts. Regardless, the nearside of the Moon appears to have more hematite than the farside, and the formation of that iron oxide remains baffling.

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No coronavirus illnesses after 1,000 HS football games

6:49 pm

Why am I not surprised? Despite more than a thousand high school football games across several states in the past month, there have been no COVID-19 outbreaks related to those games, with cases continuing to drop in each state.

Utah, for example, launched youth sports more than five weeks ago. Alabama, Indiana and Tennessee commenced with high school football roughly four weeks ago. Alaska has been allowing games for more than two weeks.

Many have been wondering whether these events would ultimately lead to an increase in COVID-19 cases being spread within communities.

Despite more than a thousand individual games having taken place, no significant recorded outbreaks of COVID-19 have occurred as a result.

Since the very start of the epidemic the evidence strongly told us that young people did not get sick from this virus. Nothing, absolutely nothing, as occurred since to change that initial assessment.

And yet American politicians tremble in terror at the idea of having children return to classrooms, and mandate that little kids wear masks. It is beyond stupid.

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A Martian starburst spider

12:44 pm

A Martian starburst spider
Click for full image.

Cool image time! The photo to the right, cropped to post here, illustrates an example of a wholly unique Martian phenomenon, that is not only unique to Mars but is also found only in its south polar regions. The image was taken on July 17, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

What we are looking at is a permanent spider formation etched into the layered deposits of ice and dirt that cover the widest area surrounding Mars’ south pole. The blue dot just north of Chasma Australe on the overview map below shows the location of these starbursts, on those layered deposits.

Each winter the poles of Mars are blanketed with a thin mantle of dry ice, generally less than six feet thick. When spring arrives and sunlight hits this mantle, it heats the ice and sand on which the mantle lies, and that warmth causes the mantle’s base to sublimate back into gas. Eventually gas pressure causes the mantle to crack at its weak points so the gas can escape. By the time summer arrives that mantle is entirely gone, all of it returning to the atmosphere as CO2 gas.

This sublimation process differs between the north and south pole, due to the different terrain found at each. In the north the mantle mostly lies on ice or sand dunes, neither of which is stable over repeated years. Thus, the mantle weak points do not occur at the exact same place each year, even though they occur at the same type of locations, such as the base and crests of dunes.
» Read more

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Bennu tosses particles from its surface routinely

9:26 am

Objects ejected from Bennu
Tracked particles after August 28, 2019 ejection event.

During OSIRIS-REx’s more than twenty months flying close to the Bennu, scientists have found that the asteroid routinely kicks particles from its surface into space, with these events linked to the asteroid’s day-night cycle.

Since arrival the scientists have seen and tracked more than 300 ejection events, with the almost seven hundred objects detected ranging from about an eighth to a half inch in size. Most moved about eight inches per second, comparable to “a beetle scurrying across the ground.”

The image to the right, cropped, reduced, and brightened to post here, comes from the introductory paper of a suite of papers on the subject, published today.

The timing of the events however reveals the most.

As Bennu completes one rotation every 4.3 hours, boulders on its surface are exposed to a constant thermo-cycling as they heat during the day and cool during the night. Over time, the rocks crack and break down, and eventually particles may be thrown from the surface. The fact that particle ejections were observed with greater frequency during late afternoon, when the rocks heat up, suggests thermal cracking is a major driver. The timing of the events is also consistent with the timing of meteoroid impacts, indicating that these small impacts could be throwing material from the surface. Either, or both, of these processes could be driving the particle ejections, and because of the asteroid’s microgravity environment, it doesn’t take much energy to launch an object from Bennu’s surface.

The link includes a cool movie showing the ejections events and the tracked paths of the ejected particles.

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NASA solicits lunar landers to bid on bringing science instruments to Moon

8:56 am

UPDATE: It appears I misunderstood the nature of this NASA solicitation in my initial post. I have rewritten it to correct it. Hat tip reader Rex Ridenoure.

Capitalism in space: NASA has issued a request from the private companies building unmanned lunar landers to bid on carrying a variety of science instruments to the Moon by ’23.

Initially NASA had indicated it was farming out the design and construction of the lunar landers to private companies, but would have the science instruments designed and built in-house. Since ’19 however NASA has had private companies designing and building these fourteen small science payloads, and is now in the process of determining which private landers will bring them to the Moon.

Though this approach is not very different than past NASA arrangements, what is different is NASA’s public approach. Instead of touting NASA’s part in this work, the agency is touting the work of the private companies.

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Another pit on Mars!

12:53 pm

Isolated small pit on Mars
Click for full image.

It has been several months since my last Martian pit update, mostly caused by the lack of new pit images coming down from the high resolution camera on Mars Reconnaissance Orbiter (MRO). I think this lack is not because of a lack of additional pits or caves but instead signals the completion of a first high resolution survey of the known pits so far found on Mars. A full list of all past pit updates can be found at the bottom of this post.

Regardless, the image to the right, cropped to post here, is the only such image in months, taken on April 14, 2020, and shows a small isolated pit in the lava slopes between the giant volcanoes Arsia and Pavonis Mons. In the full photograph you can see how isolated is this pit. To the limits of the image there are no other such features, the terrain a relatively smooth plain with only some small ridges and and a scattering of what seem to be partly obscured or eroded small craters.

The overview below map shows this pit’s relationship to the volcanoes as well as to all other known nearby pits.
» Read more

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Astronomers look at one patch of sky and see no signs of alien life

9:12 am

Worlds without end: Using an Australian radio telescope array focused in the FM frequencies, astronomers did a seventeen hour sweep of one small of sky and found no evidence of alien transmissions.

“We observed the sky around the constellation of Vela for 17 hours, looking more than 100 times broader and deeper than ever before. With this dataset, we found no technosignatures—no sign of intelligent life.”

Professor Tingay said even though this was the broadest search yet, he was not shocked by the result. “As Douglas Adams noted in The Hitchhikers Guide to the Galaxy, ‘space is big, really big’. … And even though this was a really big study, the amount of space we looked at was the equivalent of trying to find something in the Earth’s oceans but only searching a volume of water equivalent to a large backyard swimming pool.

The radio array used in this search is only a small precursor to a much larger array, dubbed the Square Kilometer Array (SKA), which is under construction and many times more sensitive.

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Strange glacial flow features on Mars?

1:16 pm

Flow features in Reull Vallis
Click for full image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on May 26, 2020, and shows what the scientists dub “Flow features in Reull Vallis.”

These features are typical in the mid-latitudes, and once again suggest the presence of buried glacial ice. The two lobes on the left and right both evoke such flows, as does the material in the drainage channel near the top of the photo.

What is more intriguing however are the strange features in the box. Below is that section, at full resolution.
» Read more

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Sunspot update: More evidence of an upcoming maximum

11:39 am

NOAA last week updated its monthly graph for tracking the Sun’s monthly sunspot activity. As I have done now for every month since 2011, I am posting that graph elow with additional annotations by me to show the past and new solar cycle predictions.

August 2020 sunspot activity

The graph above has been modified to show the predictions of the solar science community for the previous solar maximum. The green curves show the community’s two original predictions from April 2007 for the previous maximum, with half the scientists predicting a very strong maximum and half predicting a weak one. The blue curve is their revised May 2009 prediction. The red curve is the new prediction, first posted by NOAA in April 2020.

August continued the trends seen in the past two months whereby sunspot activity actually exceeded the prediction for this particular month.

Does this mean the prediction of a weak maximum in 2025 will be wrong? Hardly. Sunspot activity in any given month can easily be above or below the prediction, as is obvious if you compare the fluctuations of the last maximum with the prediction. We will not really know if these higher numbers the past few months mean anything until a lot more time has passed, with the gathering of a lot more data.

What is clear is that the activity does herald the next maximum. As in the past few months, the sunspots in August all had polarities that assigned them to the new maximum. While it is not impossible for there to be a handful of sunspots in the next few months that belong to the last maximum, it now appears that the last cycle is pretty much over. We are entering the ramp up to the next maximum, presently predicted by a portion of the solar science community aligned with NOAA to be a weak one.

Above all, the real scientific mystery remains: Scientists do not really yet understand the causes and processes that produce this sunspot cycle. They know without question that it is caused by cycles in the Sun’s magnetic dynamo, but their understanding of the details behind this process remain quite unknown.

Furthermore, the Sun’s importance to the climate on Earth is unquestioned. What we still do not know is its precise influence on long term climate changes. There is circumstantial evidence that it causes cooling and warming of the climate on scales of decades and centuries, but this remains unconfirmed. Once again, our understanding of the details behind the changes in the climate remain quite unknown.

And as always, the devil is in the details.

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The icy Erebus Mountains near where Starship will land on Mars

2:20 pm

Overview of all SpaceX images in Arcadia Planitia

Glacial filled crater in Erebus Montes
Click for full image.

It has been several months since I posted any new photos of the region on Mars which SpaceX considers its prime candidate landing site for its Starship spacecraft/rocket, now under development. The map to the right shows the location of all the images that SpaceX has obtained from the high resolution camera on Mars Reconnaissance Orbiter (MRO) of this landing region, located in the northern lowland plains at the border between Arcadia and Amazonis and to the east of the Erebus Mountains. (See my post on November 13, 2019 for an analysis of the reasoning for SpaceX to choose this region, along with links to each of the numbered images.)

Time to take another look, this time at the very center of the southern cluster of the Erebus mountains. The crater to the right, its location indicated by the tiny red rectangle on the map above, was taken by MRO on May 6, 2020, and shows the typical glacial features scientists find in mid-latitude Martian craters. The floor appears filled with glacial material, with the repeated cyclical flows repeatedly coming down off the north-facing interior rim. That rim would generally be colder and get less sunlight, so snowfall is more likely to pile up there and then flow downward like a glacier, only to sublimate away once it moves out of shadow.

What makes these mountains enticing, only about 400 miles from the Starship landing zone, is not simply what is inside this crater, but what surrounds it. Below is the wider view provided by MRO’s context camera.
» Read more

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