Tag: science

The eroding edge of Mars’ largest volcanic ash field

1:45 pm

Eroding yardangs at the edge of Mars' largest volcanic ash field
Click for full image.

Cool image time! In the regions between the biggest volcanoes on Mars is the Medusae Fossae Formation, a immense deposit of volcanic ash that extends across as much surface area as the nation of India. As planetary scientist Kevin Lewis of Johns Hopkins University explained to me previously,

In general, much of the [formation] seems to be in net erosion now, retaining very few craters on the surface. …One hypothesis is that this long term erosion, since it’s so enormous, is the primary source of the dust we see covering the much of the planet’s surface.

The image above, cropped and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on January 25, 2020. It shows one very small area at the very edge of the Medusae ash deposit, in a region where that deposit is clearly being eroding away by the prevailing southeast-to-northwest winds. The mesas of this ash that remain are called yardangs, their ash more tightly pressed together so that it resists erosion a bit longer than the surrounding material.

In the context map below the location of these yardangs is indicated by the white cross, right on the edge of the Medusae ash field.
» Read more

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A failed star with cloud bands like Jupiter’s

9:32 am

The uncertainty of science: Astronomers think they have detected cloud bands similar to Jupiter’s on a brown dwarf about 6.5 light years away.

A team of astronomers has discovered that the closest known brown dwarf, Luhman 16A, shows signs of cloud bands similar to those seen on Jupiter and Saturn. This is the first time scientists have used the technique of polarimetry to determine the properties of atmospheric clouds outside of the solar system, or exoclouds.

Brown dwarfs are objects heavier than planets but lighter than stars, and typically have 13 to 80 times the mass of Jupiter. Luhman 16A is part of a binary system containing a second brown dwarf, Luhman 16B. At a distance of 6.5 light-years, it’s the third closest system to our Sun after Alpha Centauri and Barnard’s Star. Both brown dwarfs weigh about 30 times as much as Jupiter.

Despite the fact that Luhman 16A and 16B have similar masses and temperatures (about 1,900° F or 1,000° C), and presumably formed at the same time, they show markedly different weather. Luhman 16B shows no sign of stationary cloud bands, instead exhibiting evidence of more irregular, patchy clouds. Luhman 16B therefore has noticeable brightness variations as a result of its cloudy features, unlike Luhman 16A.

This conclusion is based on studying the polarized light coming from both brown dwarfs. For Luhman 16A, the result suggested bands. For Luhman 16B, the result suggested patchy, irregular clouds like on Earth.

The emphasis should be on the words “suggested” and “uncertainty.” This is good science, but the data is very sparse. We will need to actually see at these objects to really determine their weather.

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First Fast Radio Burst discovered inside the Milky Way

2:22 pm

The uncertainty of science: Astronomers now think they have discovered the first Fast Radio Burst (FRB) to have occurred inside the Milky Way, only 30,000 light years away, and from this now hypothesize that the bursts come from a particular kind of neutron star called a magnetar because of its super-powerful magnetic field.

The key is that, using multiple different telescopes, they also detected X-ray emissions from the same object.

The X-ray counterpart to the SGR 1935+2154 burst was not particularly strong or unusual, said astrophysicist Sandro Mereghetti of the National Institute for Astrophysics in Italy, and research scientist with the ESA’s INTEGRAL satellite. But it could imply that there’s a lot more to FRBs than we can currently detect.

“This is a very intriguing result and supports the association between FRBs and magnetars,” Mereghetti told ScienceAlert. “The FRB identified up to now are extragalactic. They have never been detected at X/gamma rays. An X-ray burst with luminosity like that of SGR1935 would be undetectable for an extragalactic source.”

Of course, more data is needed, as well as more detections, but it appears that astronomers are beginning to hone in on the solution to the source of FBRs.

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The edge of Mars’ north polar ice cap

1:55 pm

The scarp face of the Martian north polar ice cap
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken on December 29, 2019 by the high resolution camera of Mars Reconnaissance Orbiter (MRO) and shows the many-layered scarp face of the Martian north polar ice cap. I have also rotated the image so that north is at the top. The overall height of this scarp is quite high, more than 3,500 feet.

There are a number of very cool features in this image. For example, note what at first look like puffs of clouds just below the contact between the bright and dark layers. I count almost two dozen, with the largest near the center. They are not cloud puffs, however, but areas scoured by past avalanches. According to Patricio Becerra at the University of Bern in Switzerland,

An image from a few years ago shows evidence for the same patches, so they likely happened a while back. When the avalanches or “block falls” occur, they scour the Basal Unit [the dark layer] and break up the exposed surface, causing a brighter/cloudier appearance of the ground than the undisturbed parts.

Avalanches on the scarps of the North Pole icecap occur in great numbers at the beginning of every Martian summer. As sunlight hits the scarp, it causes the carbon dioxide frost layer that settled on the cap during the winter to sublimate away as vapor, and like the freeze-melt cycle on Earth, this sublimation disturbs any unstable ice boulders on the scarp face.

During the early Martian summer, images from MRO routinely capture many such avalanches. Scientists think there could be hundreds to thousands every summer. In many ways, this is similar to the large pieces of ice that routinely calf off the foot of glaciers here on Earth, and that tourists take cruise ships to see in the inside passage of Alaska.

For context, the overview map below indicates with a gold cross where on the icecap’s edge this image is located. The red and pink areas indicate the vast dune fields that surround the icecap.
» Read more

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Scientists better constrain time frame of Mars’ active dynamo

12:33 pm

Using data from the MAVEN orbiter, scientists have now constrained the time frame when Mars’ dynamo was active and producing a global magnetic field, between 3.7 and 4.5 billion years ago.

Magnetism in certain rocks on Mars’ surface indicate that the Martian dynamo was active between 4.3 and 4.2 billion years ago, but the absence of magnetism over three large basins – Hellas, Argyre, and Isidis – that formed 3.9 billion years ago has led most scientists to believe the dynamo was inactive by that time.

Mittelholz’s team analyzed new data from NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) orbiter and found clear evidence of a magnetic field coming from the Lucus Planum lava flow that formed about 3.7 billion years ago – much later than at other areas studied.

There is of course a lot of uncertainty here.

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Europa’s mysterious stained grooves

11:18 am

Europa's jumbled icepack
Click for full image.

From 1995 to 2003 the Galileo orbiter circled Jupiter 34 times. During those orbits the spacecraft made numerous close fly-bys of Jupiter’s moons, including eleven past the tantalizingly mysterious moon Europa.

The image to the right was taken during the eighth fly-by of Europa. It is one of three Galileo images of Europa that scientists have pulled from the Galileo archive and subjected to modern computer processing in order to improve what can be seen. The other two can be found here and here. From the release for the image to the right:

All three images were captured along the same longitude of Europa as Galileo flew by on Sept. 26, 1998, in the spacecraft’s 17th orbit of Jupiter (orbit E17). It was the eighth of Galileo’s 11 targeted flybys of Europa. High-resolution images were taken through a clear filter in grayscale (black and white). Using lower-resolution, color images of the same region from a different flyby (orbit E14), technicians recently mapped color onto the higher-resolution images.

In other words, they laid the colors from a lower resolution color image on top of the high resolution black & white image so that we could see these three images in color. The blue and white areas are made of up water ice, while the reddish areas are made up of “more non-ice materials.”

The vagueness for describing the non-ice materials is intentional, as scientists still do not know what they made of. They do believe that this material came from the planet’s interior, as the red material is always found aligned with the cracks, fissures, and grooves, as illustrated clear by this image.

What has always struck me about this surface of Europa since I first saw similar Galileo images back in 1998 and wrote about them for the magazine The Sciences is how much it resembles the Arctic ice pack as seen by early explorers during their attempts to reach the North Pole, jumbled jigsaw pieces of ice packed together but moving slowly so that the cracks between them shift and change over time.

The resemblance adds weight to the theory that there is a liquid ocean below Europa’s icepack, and the red material hints at some intriguing chemistry coming from that ocean.

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Starlink satellites, not aliens, are those strings of lights in the night sky

1:12 pm

Apparently many people have been seeing the reflected strings of SpaceX’s new Starlink satellites in the night sky, and are calling news organizations asking about them.

Some viewers have noticed the “lights” in the sky will go dark, one by one. This is due to the reflection of light from the moon and Earth and how the position of the satellites change.

Elon Musk, the founder and CEO of SpaceX, detailed a plan this week to “mitigate the impact of their Starlink satellite constellation on night sky observation,” according to an article on Tech Crunch.

In that Tech Crunch article, Musk describes how they are installing sun visors on the satellites to prevent the reflections and make them hopefully invisible to the Earthbound observers.

This will make the astronomy crowd happy, which wants its new big ground-based telescopes to be useful. I think they should instead be focusing their effort in building more space-based telescopes.

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The Sun fluctuates far less than other similar stars

12:24 pm

A new survey of 369 sun-like stars has confirmed what earlier studies have shown, that the Sun is remarkable inactive compared with similar stars.

A comprehensive catalogue containing the rotation periods of thousands of stars has been available only for the last few years. It is based on measurement data from NASA’s Kepler Space Telescope, which recorded the brightness fluctuations of approximately 150000 main sequence stars (i.e. those that are in the middle of their lifetimes) from 2009 to 2013. The researchers scoured this huge sample and selected those stars that rotate once around their own axis within 20 to 30 days. The Sun needs about 24.5 days for this. The researchers were able to further narrow down this sample by using data from the European Gaia Space Telescope. In the end, 369 stars remained, which also resemble the Sun in other fundamental properties.

The exact analysis of the brightness variations of these stars from 2009 to 2013 reveals a clear picture. While between active and inactive phases solar irradiance fluctuated on average by just 0.07 percent, the other stars showed much larger variation. Their fluctuations were typically about five times as strong. “We were very surprised that most of the Sun-like stars are so much more active than the Sun,” says Dr. Alexander Shapiro of MPS.

It is possible that this inactivity might be because the Sun just happens to be going through a quiet phase, but that is becoming increasingly less likely as the surveys find more and more sun-like stars, and none as inactive as the Sun.

If the Sun is this unusual, we must ask if this inactivity is a fundamental requirement for life to form. Active stars provide a more inhospitable environment. If inactive stars like the Sun are very rare, however, that suggests that life itself in the universe could be very rare as well.

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Hubble photographs break-up of Comet ATLAS

10:53 am

The break-up of Comet ATLAS
For the full images go to April 20 and April 23.

Cool image time! Scientists using the Hubble Space Telescope have captured the break-up of Comet ATLAS over a period of several days. The two images to the right, cropped and annotated to post here, were taken on April 20th and April 23rd respectively.

Hubble identified about 30 fragments on April 20, and 25 pieces on April 23. They are all enveloped in a sunlight-swept tail of cometary dust. “Their appearance changes substantially between the two days, so much so that it’s quite difficult to connect the dots,” said David Jewitt, professor of planetary science and astronomy at UCLA, Los Angeles, California, leader of one of two teams who photographed the doomed comet with Hubble. “I don’t know whether this is because the individual pieces are flashing on and off as they reflect sunlight, acting like twinkling lights on a Christmas tree, or because different fragments appear on different days.”

That there are fewer pieces in the later image could also be because the smaller fragments had crumbled even more during the three days between photos, and thus were simply too small to see any longer.

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A Martian lava flood plain

1:21 pm

A Martian lava flood plain?
Click for full image.

Cool image time! The photo to the right, cropped to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on March 2, 2020, and shows some inexplicable shallow pits and depressions in the middle of a relatively flat and featureless plain.

Make sure you click on the image to see the full photo. Though the plain looks remarkably smooth, a handful of dark splotches are scattered about, almost all of which occur on top of small craters.

What causes these depressions? The MRO team calls this “Landforms near Cerberus Tholi.” Cereberus Tholi is a a collection of several indistinct and relatively small humps that scientists think might be shield volcanoes.

More clues come from the overall context.
» Read more

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More data from interstellar Comet 2I/Borisov as it zipped past Sun in December

10:00 am

Astronomers studying interstellar Comet 2I/Borisov as it zipped past Sun in December have found that while in many ways it resembled solar system comets, the differences were revealing.

During its trip through the solar system, the comet lost nearly 61 million gallons (230 million liters) of water — enough to fill over 92 Olympic-size swimming pools. As it moved away from the Sun, Borisov’s water loss dropped off — and did so more rapidly than any previously observed comet. Xing said this could have been caused by a variety of factors, including surface erosion, rotational change and even fragmentation. In fact, data from Hubble and other observatories show that chunks of the comet broke off in late March.

…Swift’s water production measurements also helped the team calculate that Borisov’s minimum size is just under half a mile (0.74 kilometer) across. The team estimates at least 55% of Borisov’s surface — an area roughly equivalent to half of Central Park — was actively shedding material when it was closest to the Sun. That’s at least 10 times the active area on most observed solar system comets. Borisov also differs from solar system comets in other aspects. For example, astronomers working with Hubble and the Atacama Large Millimeter/submillimeter Array, a radio telescope in Chile, discovered Borisov produced the highest levels of carbon monoxide ever seen from a comet at that distance from the Sun.

Because more of the comet’s entire surface had water ice than seen in solar system comets, it suggests that the comet has never been close to another star before. That the water release dropped off precipitously however also suggests that that surface layer of ice was not very deep.

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Of almost 3,300 prisoners infected with COVID-19, 96% have no symptoms

10:05 am

Almost 3,300 prisoners in four state U.S. prison have tested positive for the Wuhan flu, with 96% exhibiting no symptoms at all.

When the first cases of the new coronavirus surfaced in Ohio’s prisons, the director in charge felt like she was fighting a ghost. “We weren’t always able to pinpoint where all the cases were coming from,” said Annette Chambers-Smith, director of the Ohio Department of Rehabilitation and Correction. As the virus spread, they began mass testing.

They started with the Marion Correctional Institution, which houses 2,500 prisoners in north central Ohio, many of them older with pre-existing health conditions. After testing 2,300 inmates for the coronavirus, they were shocked. Of the 2,028 who tested positive, close to 95% had no symptoms. “It was very surprising,” said Chambers-Smith, who oversees the state’s 28 correctional facilities.

As mass coronavirus testing expands in prisons, large numbers of inmates are showing no symptoms. In four state prison systems — Arkansas, North Carolina, Ohio and Virginia — 96% of 3,277 inmates who tested positive for the coronavirus were asymptomatic, according to interviews with officials and records reviewed by Reuters. That’s out of 4,693 tests that included results on symptoms.

Being a Reuters story, the goal is to spin this result as a terrifying disaster: “We can’t contain it! The disease is everywhere!”

In truth, this result is once again remarkably encouraging. It once again shows that the Wuhan flu is simply no threat to a very large percentage of the population, and that if enough of that population would stop social distancing and allow the infection to spread, they would end up killing it because it would soon have no place to go.

It also lends weight to the hypothesis that death rate from coronavirus is really not much different than the flu. There are almost certainly a vast number of people out there infected with the Wuhan virus who have showed no symptoms, meaning that our present estimates of the death rate are much too high.

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Movie of OSIRIS-REx’s 1st landing rehearsal

12:55 pm

Closest NavCam-2 image during rehearsal
Click for full movie.

The OSIRIS-REx science team has released a short movie taken by one of the spacecraft’s navigation camera (NavCam-2) during its first landing rehearsal on April 14. The image to the right, cropped to post here, is the closest image in the sequence, and shows the relatively smooth Nightingale target landing site near the bottom of the image, approximately 50 feet in diameter.

According to the release,

NavCam 2 captures images for the spacecraft’s Natural Feature Tracking (NFT) navigation system. The NFT system allows the spacecraft to autonomously guide itself to Bennu’s surface by comparing real-time images with an onboard image catalog. As the spacecraft descends to the surface, the NFT system updates the spacecraft’s predicted point of contact depending on OSIRIS-REx’s position in relation to Bennu’s landmarks. During the sample collection event, scheduled for August, the NavCam 2 camera will continuously image Bennu’s surface so that the NFT system can update the spacecraft’s position and velocity relative to Bennu as it descends towards the targeted touchdown point.

When the image above was taken the spacecraft was at its closest point, about 213 feet above the surface. Based on this movie, it looks like the system was working, and the spacecraft was refining its aim to head towards Nightingale.

Still, the landing site is not in the center of the image, which I would think is a concern, especially because Nightingale is only one-third the size of the kind of smooth target areas they had designed the system for. (When launched they expected to see smooth areas at least 160 feet across, and designed the system for this.)

The second rehearsal is presently scheduled for June 23, and will drop OSIRIS-REx to within 82 feet of the surface.

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Scientists fine tune the cause of the super-rotation of Venus’ atmosphere

10:39 am

Scientists using data collected from the Japanese Venus orbiter Akatsuki have now refined their theories on the atmospheric processes that cause that atmosphere to rotate sixty times faster than the planet.

This super-rotation increases with altitude, taking only four Earth days to circulate around the entire planet towards the top of the cloud cover. The fast-moving atmosphere transports heat from the planet’s dayside to nightside, reducing the temperature differences between the two hemispheres.

What they found was that at equatorial latitudes the heat transfer is generated by what they call “atmospheric tidal waves”, generated by the dayside solar heat. At high latitudes the transfer is instead caused by atmospheric turbulence.

From what I can gather, they are calling these tidal waves because the Sun’s heat causes the atmosphere to expand upward on the day side, much as the Moon’s gravity pulls the ocean upward on Earth. It then is quickly drawn to the colder night side, driven I think in one direction because of the planet’s slow rotation.

As always, we must recognize the uncertainties. The data here is somewhat limited because there have been so few atmospheric orbiters so far sent to study Venus. While several future missions are under study in the U.S. and Russia, only India appears to have one targeted for launch, though the date has been pushed back from 2020 to 2023.

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China names its 2020 Mars mission

10:19 am

China’s official state-run press today announced that their 2020 Mars mission will be called Tianwen-1, noting that this name will be applied to all further planetary missions.

The link goes to that government state-run press, which provides no further information on Tianwen-1, such as where on Mars its lander/rover will land, its exact launch date, the instruments on board, etc. So far very very few details have been released.

What this propaganda press announcement does do is spout a lot of blather about how wonderful China is, and how we should all be thankful the communists have been in charge there. Here are some snippets to lighten your day:

  • …signifying the Chinese nation’s perseverance in pursuing truth and science
  • …a window for the Chinese public and the world to get a better understanding of China’s aerospace progress.
  • Chinese space engineers and scientists have overcome various difficulties and achieved aerospace development through self-reliance and independent innovation.
  • …promoting human welfare on the basis of equality, mutual benefit, peaceful utilization and inclusive development.

While China’s achievements in space are real (though much of the engineering was stolen or borrowed from others), these propaganda claims are junk and lies. Chinese space engineers are “self-reliant” and have “independence”? Don’t make me laugh. Everything done in their space program is dictated and controlled from the top, by the Chinese government and the Communist Party. No one is free to do anything, without their permission.

As for China’s pursuit of “truth and science”, their behavior during the Wuhan flu epidemic, originating from their country and very possibly caused deliberately or incompetently by them, makes this claim ludicrous on its face. They have lied, arrested scientists, blocked research, and distorted the scope and magnitude of the epidemic from day one.

Even a tiny bit of truth from them, from the beginning, might have prevented the panic that has overtaken the world which in turn appears to have triggered the next great economic depression, what I like to now call the Great Wuhan Depression.

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The first complete geologic map of Moon

9:15 am

Geologic map of Moon

Using data from several recent lunar orbiters, scientists have compiled and now released the first comprehensive geologic map of the Moon.

To create the new digital map, scientists used information from six Apollo-era regional maps along with updated information from recent satellite missions to the moon. The existing historical maps were redrawn to align them with the modern data sets, thus preserving previous observations and interpretations. Along with merging new and old data, USGS researchers also developed a unified description of the stratigraphy, or rock layers, of the moon. This resolved issues from previous maps where rock names, descriptions and ages were sometimes inconsistent.

“This map is a culmination of a decades-long project,” said Corey Fortezzo, USGS geologist and lead author. “It provides vital information for new scientific studies by connecting the exploration of specific sites on the moon with the rest of the lunar surface.”

The image to the right shows the Moon’s near side.

The complete map file is free to download, and I guarantee that scientists and engineers in China are downloading it even as I type, planning to use it to establish their ownership to the Moon’s most valuable real estate that we scouted for them.

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Stucco on Mars

1:13 pm

Stucco on Mars
Click for full image.

As a break from Wuhan flu madness I give you another cool image, cropped and reduced to post here, taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO). I call this stucco on Mars because that is exactly what it looks like. It is as someone laid down a layer of damp concrete and then ran over it roughly with a trowel to raise the knobs scattered across the surface.

The uncaptioned MRO image calls this “Aligned Mounds with Broad Summit Pits”. Those aligned mounds run across the top of the image. I suspect they are pedestal craters, left over because the impact had packed and hardened the crater so that it resisted erosion as the surrounding terrain was worn away.

The two insets, posted below at full resolutoin, focus on one of those pedestal craters as well as the distinct mesa at the bottom of the photo.
» Read more

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First exoplanet imaged was nothing more than a debris cloud

2:41 pm

The uncertainty of science: What had originally been thought to be the first image ever taken of an exoplanet has now turned out to be only the fading and expanding cloud of debris, left over from a collusion.

The object, called Fomalhaut b, was first announced in 2008, based on data taken in 2004 and 2006. It was clearly visible in several years of Hubble observations that revealed it was a moving dot. Until then, evidence for exoplanets had mostly been inferred through indirect detection methods, such as subtle back-and-forth stellar wobbles, and shadows from planets passing in front of their stars.

Unlike other directly imaged exoplanets, however, nagging puzzles arose with Fomalhaut b early on. The object was unusually bright in visible light, but did not have any detectable infrared heat signature. Astronomers conjectured that the added brightness came from a huge shell or ring of dust encircling the planet that may possibly have been collision-related. The orbit of Fomalhaut b also appeared unusual, possibly very eccentric. “Our study, which analyzed all available archival Hubble data on Fomalhaut revealed several characteristics that together paint a picture that the planet-sized object may never have existed in the first place,” said Gáspár.

The team emphasizes that the final nail in the coffin came when their data analysis of Hubble images taken in 2014 showed the object had vanished, to their disbelief. Adding to the mystery, earlier images showed the object to continuously fade over time, they say. “Clearly, Fomalhaut b was doing things a bona fide planet should not be doing,” said Gáspár.

The interpretation is that Fomalhaut b is slowly expanding from the smashup that blasted a dissipating dust cloud into space. Taking into account all available data, Gáspár and Rieke think the collision occurred not too long prior to the first observations taken in 2004. By now the debris cloud, consisting of dust particles around 1 micron (1/50th the diameter of a human hair), is below Hubble’s detection limit. The dust cloud is estimated to have expanded by now to a size larger than the orbit of Earth around our Sun.

This is not the first exoplanet that astronauts thought they had imaged, only to find out later that it was no such thing.

Remember this when next you hear or read some scientist telling you they are certain about their results, or that the science is “settled.” Unless you can get close enough to get a real picture in high resolution, or have tons of data from many different sources over a considerable period of time, and conclusions must always be subject to skepticism

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Rock droplets hitting a Martian plain

12:42 pm

Depressions in Amazonis Planitia
Click for full image.

Cool image time! The photo the right, rotated, cropped, and reduced to post here, is not only cool, it contains a punchline. It was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on February 11, 2020 and shows one small area between two regions in the northern lowlands of Mars, dubbed Amazonia Planitia (to the south) and Arcadia Planitia (to the north) respectively.

This region is thought to have a lot of water ice just below the surface., so much in fact that Donna Viola of the University of Arizona has said, “I think you could dig anywhere to get your water ice.”

I think this image illustrates this fact nicely. Assuming the numerous depressions seen here were caused by impacts, either primary or secondary, it appears that when they hit the ground the heat of that impact was able to immediately melt a wide circular area. My guess is that an underwater ice table immediately turned to gas so that the dusty material mantling the surface then sagged, creating these wider circular depressions.

Of course, this is merely an off-the-cuff theory, and not to be taken too seriously. Other processes having nothing to do with impacts could explain what we see. For example, vents at the center of these craters might have allowed the underground ice to sublimate away, thus allowing the surface to sag.

So what’s the punchline?
» Read more

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Interstellar Comet 2I/Borisov has an excess of carbon monoxide

8:48 am

Astronomers using two difference space telescopes have found that Comet 2I/Borisov, the first known interstellar comet, has an abundance of carbon monoxide when compared to solar system comets.

The team used Hubble’s unique ultraviolet sensitivity to spectroscopically detect carbon monoxide gas escaping from comet Borisov’s solid comet nucleus. Hubble’s Cosmic Origins Spectrograph observed the comet on four separate occasions, from Dec. 11, 2019 to Jan. 13, 2020, which allowed the researchers to see the object’s chemical composition change quickly, as different ice mixtures, including carbon monoxide, oxygen, and water, sublimated under the warmth of the Sun.

The Hubble astronomers were surprised to find that the interstellar comet’s coma, the gas cloud surrounding the nucleus, contains a high amount of carbon monoxide gas, at least 50% more abundant than water vapor. This amount is more than three times higher than the previously measured quantity for any comet entering the inner solar system. The water measurement was made by NASA’s Neil Gehrels-Swift satellite, whose observations were conducted in tandem with the Hubble study.

Carbon monoxide ice is very volatile. It doesn’t take much sunlight to heat the ice and convert it to gas that escapes from a comet’s nucleus. For carbon monoxide, this activity occurs very far from the Sun, about 11 billion miles away, more than twice the distance of Pluto at its farthest point from the Sun. In contrast, water remains in its icy form until about 200 million miles from the Sun, the approximate distance of the inner edge of the asteroid belt.

However, for comet Borisov, the Hubble measurements suggest that some carbon monoxide ice was locked inside the comet’s nucleus, revealed only when the Sun’s heat stripped away layers of water ice. “The amount of carbon monoxide did not drop as expected as the comet receded from the Sun. This means that we are seeing the primitive layers of the comet, which really reflect what this object is made of,” Bodewits explained. “Because of the abundance of carbon monoxide ice that survived so close to the Sun, we think that comet Borisov comes from a much colder place and from a very different debris disk around a star than our own.”

With solar system comets, the ratios between water and carbon monoxide are the reverse, with much more water detected. They theorize, based on these results, that the comet might have come from a cool red dwarf star, but with the available data that is nothing more than a guess at this point.

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Strange terrain in the Martian lowlands

12:42 pm

Strange terrain in northern lowlands
Click for full image.

Cool image time! The science team for the high resolution camera on Mars Reconnaissance Orbiter (MRO) yesterday released a new captioned image, entitled “Disrupted Sediments in Acidalia Planitia”, noting that the photo

…shows a pitted, blocky surface, but also more unusually, it has contorted, irregular features.

Although there are impact craters in this area, some of the features … are too irregular to be relic impact craters or river channels. One possibility is that sedimentary layers have been warped from below to create these patterns. The freezing and thawing of subsurface ice is a mechanism that could have caused this.

The image to the right, rotated, cropped, and reduced to post here, shows the lower quarter of the full image. While in some areas it does appear as if changes below the surface caused the surface to warp and collapse, as suggested by the caption, in other places it looks more like the top layers themselves sublimated away without disturbing what was below them.

Note for example the pits near the bottom of the photograph. They clearly show sedimentary layers on their cliff walls, including the tiny circular mesa in the middle of the rightmost pit.

If these pits were collapsing from below, their cliffs would be more disturbed, because it would have been those lower layers that sublimated first. Instead, it appears that the top layer disappeared first, followed by each lower layer, one by one.

This region of strange terrain is located in the middle of the northern lowland plains. The overview map below gives some context, with the small white box showing this photo’s location.
» Read more

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Space radiation may increase risk of cancer

8:59 am

Using mice and models, scientists have concluded that humans who spend long periods in space, exposed to its radiation, will have a 3% higher risk for cancer.

A team led by researchers at Colorado State University and Frederick National Laboratory for Cancer Research, which is part of the National Institutes for Health, used a novel approach to test assumptions in a model used by NASA to predict these health risks. Based on the NASA model, the team found that astronauts will have more than a three percent risk of dying of cancer from the radiation exposures they will receive on a Mars mission. That level of risk exceeds what is considered acceptable. [emphasis mine]

And how did they come to this conclusion?

…For the study, Weil and first author Dr. Elijah Edmondson, a veterinary pathologist and researcher based at the Frederick National Laboratory for Cancer Research in Maryland, used a unique stock of genetically diverse mice, mimicking a human population. Mice were divided into three groups with the first group receiving no radiation exposure and the other two receiving varying levels of exposure.

Edmondson, who conducted the research while completing a veterinary residency in pathology at CSU, said that for this type of research project, genetic variability is crucial. “Humans are very genetically diverse,” he explained. “You want to model that when it’s appropriate and feasible to do so.”

Weil said although the research team saw different tumor types, similar to humans, but the heavy ions did not cause any unique types of cancer. They also saw differences by sex. In humans, women are more susceptible to radiation-induced cancers than men; one of the main reasons is that women live longer, allowing sufficient time for cancer to develop. In assessing the cancer risk between male and female mice in the study, scientists said the findings parallel human data.

Edmondson said the study validates the NASA model to measure cancer risks for humans from space radiation.

In a sense, this study is junk. First, it discovers the obvious (radiation increases your chances of getting cancer). Second, it is too model-dependent, so assigning any precise percentage to that increase in humans is absurd, especially when based on a sample comprised of mice.

Third, and most important, it completely forgets the reality that life is risk, exploration is dangerous, and to do great things you need to take greater chances. That NASA concludes these questionable numbers are unacceptable means that NASA will never send humans anywhere beyond Earth orbit. Ever.

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Chang’e-4 and Yutu-2 reactivated for 17th lunar day on Moon’s surface

8:40 am

Engineers have reactivated both the lander Chang’e-4 and the rover Yutu-2 for their seventeenth lunar day on the far side of the Moon.

The report comes from the state-run Chinese press, so of course, it provides no useful new information other than what I wrote above. It did have this bit of Chinese propaganda, however:

The Chang’e-4 mission embodies China’s hope to combine wisdom in space exploration with four payloads developed by the Netherlands, Germany, Sweden and Saudi Arabia. [emphasis mine]

China’s wisdom sure did everyone a lot of good in Wuhan, didn’t it?

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Rover update: Curiosity heads downhill

2:49 pm

Curiosity's last look across the Greenheugh Pedimont
Click for higher resolution.

[For the overall context of Curiosity’s travels, see my March 2016 post, Pinpointing Curiosity’s location in Gale Crater. For the updates in 2018 go here. For a full list of updates before February 8, 2018, go here.]

After finally reaching the top of the Greenheugh Pedimont (see both the March 4 and March 8, 2020 rover updates) and spending more than a month there, drilling one hole, getting samples, and taking a lot of photos, the Curiosity science team in the past week has finally sent the rover retreating back downhill, following the same route it used to climb uphill.

The panorama above was taken on April 10, 2020, and shows the last view looking south across that pedimont towards Mount Sharp, before that descent. As you can see, trying to traverse that terrain would have been very difficult, and probably very damaging to Curiosity’s wheels.
» Read more

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Movie of OSIRIS-REx touch-and-go rehearsal

10:47 am

Checkpoint rehearsal: last image
Click for movie.

The OSIRIS-REx science team yesterday released a short movie, compiled from thirty images taken during the April 14, 2020 rehearsal of the spacecraft’s planned August touch-and-go sample grab from the asteroid Bennu.

The rehearsal brought the spacecraft through the first two maneuvers of the sampling event to a point approximately 213 feet (65 meters) above the surface, before backing the spacecraft away. These images were recorded over a ten-minute span between the execution of the rehearsal’s “Checkpoint” burn, approximately 394 feet (120 meters) above the surface, and the completion of the back-away burn, which occurred approximately 213 feet (65 meters) above the surface. The spacecraft’s sampling arm – called the Touch-And-Go Sample Acquisition Mechanism (TAGSAM) – is visible in the central part of the frame, and the relatively clear, dark patch of Bennu’s sample site Nightingale is visible in the later images, at the top. The large, dark boulder that the spacecraft approaches during the sequence is 43 feet (13 meters) on its longest axis.

The image to the right is the last frame of the movie, as the spacecraft has begun its retreat. The smoother area of Nightingale is at the top.

Based on the video, it appears as if the spacecraft would have missed the Nightingale target site had the rehearsal continued to touchdown. This might not be so, however. And even if it is, the reason for the rehearsal is to allow engineers to refine the process to make it more accurate. We shall see what changes in the second rehearsal in about a month or so.

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Astronomers claim to have discovered most powerful supernova ever

9:38 pm

The uncertainty of science: Astronomers have now calculated that a supernova that was spotted in 2016 was possibly the brightest ever detected, and might have been caused by the merger of two massive stars, each about sixty times as massive as the Sun.

SN 2016aps was discovered by the Panoramic Survey Telescope and Rapid Response System (Pan- STARRS) Survey for Transients on February 22, 2016 with an apparent magnitude of 18. Also known as PS16aqy, the explosion occurred in a low-mass galaxy some 3.1 billion light-years from Earth.

University of Birmingham’s Dr. Matt Nicholl and colleagues believe SN 2016aps could be an example of an extremely rare ‘pulsational pair-instability’ supernova, possibly formed from two massive stars that merged before the explosion. Such an event so far only exists in theory and has never been confirmed through astronomical observations.

…The researchers observed SN 2016aps for two years, until it faded to 1% of its peak brightness. Using these measurements, they calculated the mass of the supernova was between 50 to 100 solar masses. Typically supernovae have masses of between 8 and 15 solar masses.

They theorize that the supernova became especially bright when the explosion collided with a gas shell that already surrounded both stars.

Lots of assumptions and guesswork here, based on a tiny amount of data. The biggest lack is that they don’t have any observations of the star (or stars) prior to the supernova, so any theory about what those stars were like is exactly that, a theory.

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Baby Martian volcanoes

1:28 pm

Cratered cone near Noctis Fossae
Click for full image.

Cool image time! I came across this strange feature shown on the right in my normal rummaging through the archive of the high resolution camera on Mars Reconnaissance Orbiter (MRO). The photo, rotated, cropped, and reduced to post here, focuses on what they label a “cratered cone.”

The immediate thought is that this is a volcano cone, and the craters at its peak are not impact craters but calderas. In science however such a knee-jerk conclusion is always dangerous. For example, this might instead be a pedestal crater, where the surrounding terrain was worn away over eons, leaving the crater sitting high and dry.

It is therefore important to look deeper to determine what origin of this feature might be.

First, its location, as shown in the overview map below, provides us our first clue.
» Read more

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Earth-sized exoplanet in habitable zone found in old Kepler data

10:25 am

A review of the data produced by the space telescope Kepler, now retired, has discovered an exoplanet about the same size as Earth and also located in the habitable zone that had been missed previously by software.

Scientists discovered this planet, called Kepler-1649c, when looking through old observations from Kepler, which the agency retired in 2018. While previous searches with a computer algorithm misidentified it, researchers reviewing Kepler data took a second look at the signature and recognized it as a planet. Out of all the exoplanets found by Kepler, this distant world – located 300 light-years from Earth – is most similar to Earth in size and estimated temperature.

This newly revealed world is only 1.06 times larger than our own planet. Also, the amount of starlight it receives from its host star is 75% of the amount of light Earth receives from our Sun – meaning the exoplanet’s temperature may be similar to our planet’s as well. But unlike Earth, it orbits a red dwarf. Though none have been observed in this system, this type of star is known for stellar flare-ups that may make a planet’s environment challenging for any potential life.

A number of Earth-like planets have been found around red dwarf stars. Whether life could evolve in such places is entirely unknown. Red dwarfs are small, and would have likely formed in a nebula cloud with a dearth of many elements and materials needed for life. Moreover, because they are also so dim, the habitable zone is very near the star, meaning that, as the article mentions, strong flares are more dangerous.

At the same time, red dwarfs are the most common star, and the most long-lived, capable of burning for tens of billions of years. With enough time and numbers anything is still possible.

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Confirmed: Comet ATLAS has broken apart

8:47 am

Astronomers have now confirmed the fact that Comet ATLAS has broken into several pieces, and will not put on a spectacular sky show this coming May.

Just a month ago, it looked like the icy wanderer, officially known as C/2019 Y4 Atlas, might put on a dazzling sky show around the time of its closest approach to the sun, or perihelion, which occurs on May 31.

But relatively lackluster behavior soon dimmed such hopes. And optimism surrounding the comet is now pretty much extinguished, for it’s no longer in one piece. Comet Atlas “has shattered both its and our hearts,” astrophysicist Gianluca Masi, the founder and director of the Virtual Telescope Project in Italy, said in an emailed statement on Sunday (April 12). “Its nucleus disintegrated, and last night I could see three, possibly four main fragments.”

A nice picture of the break-up can be seen here.

We are due for another great comet, like Comet Hale-Bopp in the late 1990s. Unfortunately, Comet ATLAS won’t be that comet.

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OSIRIS-REx successfully completes touch-and-go rehearsal

8:44 am

OSIRIS-REx yesterday successfully completed its first dress rehearsal of the maneuver that will allow it in August to touch the surface of the asteroid Bennu and grab a sample.

Four hours after departing its 0.6-mile (1-km) safe-home orbit, the spacecraft performed the Checkpoint maneuver at an approximate altitude of 410 feet (125 meters) above Bennu’s surface. From there, the spacecraft continued to descend for another nine minutes on a trajectory toward – but not reaching – the location of the sampling event’s third maneuver, the “Matchpoint” burn. Upon reaching an altitude of approximately 246 ft (75 m) – the closest the spacecraft has ever been to Bennu – OSIRIS-REx performed a back-away burn to complete the rehearsal.

During the rehearsal, the spacecraft successfully deployed its sampling arm, the Touch-And-Go Sample Acquisition Mechanism (TAGSAM), from its folded, parked position out to the sample collection configuration. Additionally, some of the spacecraft’s instruments collected science and navigation images and made spectrometry observations of the sample site, as will occur during the sample collection event.

They plan one more rehearsal, getting even closer to the asteroid, before the August 25 sample grab.

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