Tag: science

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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InSight has buried its Mole

9:58 am

The Mole buried

Using the scoop on InSight’s robot arm, engineers have now successfully filled the large hole that had formed around the spacecraft’s mole, the drill that has been trying but failing to dig down about fifteen feet so that a heat sensor could measure the internal temperature of Mars.

The image to the right shows the filled hole with the mole’s communications tether snaking away. Earlier this month they used InSight’s scoop to scrape surface material into the hole, as planned in June. According to the mole’s principle investigate, Tilman Spohn,

I had estimated that the first scrape of 12 centimetres swath length would raise the bottom of the pit but leave the Mole sticking out of the sand. By the way, this was the condition for some to agree to the quite controversial ‘scratch test’. As one can see in the image from Sol 600 shown below, that estimate was not quite right. The scraping was a complete success! The scrape was much more effective than expected and the sand filled the pit almost completely. The Mole is now covered, but there is only a thin layer of sand on the back cap.

Their next step will be to use the scoop to press down on the dirt of the filled hole, with the hope this added pressure will keep the dirt pressed against the mole as it hammers downward, thus holding it place with each downward stroke.

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Newly upgraded solar telescope sees first light

9:39 am

Early image from upgraded solar telescope.

Astronomers have finished a major instrument upgrade of the GREGOR solar telescope in the Canary Islands, making it possible for them to observe features on the Sun’s surface as small as thirty miles in diameter.

The image to the right is an example of the telescope’s new capability, showing the Sun’s granular surface features. From the introduction of the paper describing the upgrade:

GREGOR is Europe’s largest solar telescope. … Its 1.5 m diameter with an optical footprint of 1.44 m allows us to resolve structures on the Sun as small as 50 km at 400 nm.

…A past drawback of GREGOR was that its image quality did not reach the theoretical limit, partly because a risk was taken with untested technologies, such as silicon carbide mirrors, which could not be polished well enough, and partly because of design problems. These difficulties have recently been solved by replacing all silicon carbide mirrors with mirrors made of Zerodur, which can be polished to the required quality, and by redesigning the AO relay optics. GREGOR now operates at its diffraction limit. [emphasis mine]

In other words, the initial mirrors did not work as promised, requiring them to replace them to get the telescope to function as initially designed. By the image above, it looks like their upgrade has worked admirably.

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A star with giant misaligned rings

8:52 am

Star with misaligned rings

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have detected a nearby star, dubbed GW Ori, with multiple rings of dust with several tilted in relation to the others.

The rings, with dust equaling 75, 170, and 245 Earth masses each, are 46, 188, and 336 astronomical units (au) each from their star. (An au is the distance of the Earth to the Sun.) If you look closely at the image to the right, you can see that the inner rings are circular, while the outer rings appear oval, suggesting that we are looking directly down at the inner rings, but the outer rings are tilted to our line of sight. Moreover, another team of astronomers

…observed GW Ori with ALMA and the European Southern Observatory’s Very Large Telescope (VLT). Near infrared observation with VLT showed for the first time that the innermost ring casts a shadow on the outer rings, which is clear evidence of disk misalignment. Kraus and his colleagues also performed a computer simulation and suggest that the triple star system can create misaligned rings, without gravitational assistance from planets. The two teams have different theories for the origin of the misaligned rings, but no conclusions have been reached so far. Nevertheless, GW Ori is a precious example to understand planet formation in the complex gravitational environment around multiple stars. [emphasis mine]

As noted, there is no agreement on the cause of the misalignment, only that it does exist.

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Bright-tipped perplexing terrain on Mars

1:29 pm

Perplexing terrain on Mars
Click for full image.

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 June 24, 2020, and shows a bit of inexplicable country in Arabia Terra, the widest and largest transition zone region on Mars between the northern lowland plains and southern cratered highlands.

The stuff visible in this image falls into what I call “What the heck?” geology. It is very clear we are looking at a collection of straight and curved ridges and mesas, all of which for some reason are bright at their tips and edges. Some of the curved ridges might be the rims of craters, but only some. Other ridge lines look more like leftovers following a strange erosion process. The problem is that to my uneducated eye I can find little rhyme or reason to these shapes. The mesas and canyon on the image’s right edge might be explained by the erosion processes that create chaos terrain on Mars, but that process does not do a good job of explaining anything else in the photo.

That this uncaptioned image is merely labeled “Arabia Terra” suggests that the scientists involved in getting this image were equally perplexed by it, and could not give it a better description.

The overview map below provides some location context, including how this geology relates to the landing site of Europe’s Rosalind Franklin rover, now scheduled for a 2022 launch.
» Read more

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Biggest black hole merger yet detected by gravitational waves

3:30 pm

The uncertainty of science: In May 2020 scientists using the LIGO and VIGO gravitational waves telescopes detected evidence of a merger from two giant black holes, one of which was of a size that according to all theories had been considered “impossible.”

The short gravitational wave signal, GW190521, captured by the LIGO and Virgo gravitational wave observatories in the United States and Europe on 21 May last year, came from two highly spinning, mammoth black holes weighing in at a massive 85 times and 66 times the mass of the Sun, respectively.

But that is not the only reason this system is very special. The larger of the two black holes is considered `impossible’. Astronomers predict that stars between 65 – 130 times the mass of the Sun undergo a process called pair instability, resulting in the star being blown apart, leaving nothing behind.

With a mass of 85 solar masses, the larger black hole falls squarely in that forbidden range, referred to as the upper black hole mass gap, and should be `impossible’.

The explanation the scientists propose is that this black hole initially formed with a mass smaller than 65 solar masses, and then sucked in matter, including a possible additional black hole merger, that raised its weight to 85 solar masses.

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The longest lava tube in the solar system?

9:19 am

A lava tube on Mars
Click for full image.

Before I delve into today’s cool image, I think it important to explain to my readers why I seem to post so many cool images from Mars. The simple explanation is that Mars right now is where almost all the cutting edge planetary research is taking place, and as a science journalist focused on space exploration I must go to that cutting edge. My dear readers know that I love variety (just consider the evening pauses on Behind the Black), but you can’t ignore the reporting of real discoveries simply to increase the diversity of one’s posts. This is too often what modern news outlets do, which is also why they often miss the real story.

Anyway, today’s cool image to the right, rotated, cropped, and reduced to post here, shows only a small section of what might be the longest lava tube in the entire solar system. Taken on May 5, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), it shows a string of pits along a meandering depression coming down the northwest flank of the giant volcano Arsia Mons. The image was a follow-up to a July 2014 photo of the same location, and was taken to produce a stereo pair.

The feature strongly suggests a lava tube, with the pits being skylights into the meandering underground void. From top to bottom this section of the tube is a little over three miles long. Since there are lava tubes on Earth far longer, this one image hardly makes this the longest tube in the solar system.

The tube, however, extends off the image both at the bottom and at the top. Not many high resolution images have been taken in this area, so it is therefore hard to say how far the tube extends. Other nearby high resolution images in this area however have found similar lava tubes, which conceivably could be part of the same tube. The overview map below shows the relationship.
» Read more

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A collapsed Martian crater in a glacier?

12:43 pm

Collapsed crater in glacier?
Click for full image.

Today’s cool image to the right, cropped and reduced to post here, is another example of evidence that the mid-latitudes of Mars are covered with glaciers and ice. The photo, taken on April 25, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), shows many of the squashed and blobby features found in these mid-latitudes.

What makes the image even more interesting is the small crater in the center of the larger crater. The floor of that larger crater seems filled with glacial fill, and it appears that when that smaller impact occurred it caused the nearby surrounding fill to collapse downward, producing the oblong off-center depression. At least that’s my uneducated guess, which I admit could easily be wrong.

Even if my hypothesis is wrong, the visual evidence here supports the theory that this region, dubbed Deuteronilus Mensae, has lots of buried ice glaciers. Consider for example the distorted crater to the southwest of the big crater. It sure looks like at some point it was heated suddenly, maybe by the impact of the main crater, so that its rim was warped and reshaped, in the manner that ice would be warped and reshaped by sudden heat. Moreover, all the craters in full image appear to have glacial fill.

The overview map below adds weight to this conclusion.
» Read more

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Revisiting Mars’ glacier country

1:16 pm

Glacial cracks or pits on Mars
Click for full image.

With today’s cool image we return to what I have labeled glacier country on Mars, though this time the image shows a Martian glacial feature that while resembling vaguely such features seen on Earth, has an alienness to it that requires some explanation.

The photo to the right, cropped to post here, was taken on March 24, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The section I have focused on is the floor of a depression with a number of parallel pits, more or less aligned with the packed north-south ridges that cover the entire floor.

Normally, the north-south ridges would suggest repeated glacial flows moving to either the west or to the east. Such movement could over time, cause the ridges to separate, creating the cracks or pits that we see here. The trouble is that the slope of this depression is very unclear. In fact, the wider view below shows that this depression appears mostly enclosed, or if not it does not seem to be flowing in any particular direction.
» Read more

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Problem with InSight’s weather station

3:18 pm

Engineers are troubleshooting a problem with the weather sensors on the InSight lander on Mars that has prevented them from collecting data since August 16th.

[The weather system] is in safe mode and unlikely to be reset before the end of the month while mission team members work toward a diagnosis. JPL engineers are optimistic that resetting the control computer may address the issue but need to investigate the situation further before returning the sensors to normal.

Overall InSight has turned out to be of mixed success. The seismometer has worked as planned, but the mole designed to drill the heat thermometer sixteen feet into the ground has so far failed to work, and now the weather station has shut down, though hopefully only temporarily.

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Cracks and scallops on the lowland plains of Mars

2:37 pm

Utopia Basin cracks and scallops
Click for full image.

Cool image time! To the right is some of the strange terrain seen in the northern lowland plains of Mars. The photo, cropped to post here, was taken on May 4, 2020 by the high resolution camera of Mars Reconnaissance Orbiter (MRO) of an area in the northwest part of Utopia Planitia.

Next year China’s first attempt to soft land a rover on Mars will occur somewhere in Utopia Planitia. Utopia Planitia, also called Utopia Basin, is quite large, however, and in fact is the largest recognizable impact basin on Mars, with a diameter of more than 2,000 miles or about two thirds the width of the United States. If this strange spot was put near Seattle, Tianwen-1 is expected to touch down somewhere near Houston, Texas.

The MRO science team labeled the image “Scalloped terrain in Utopia Planitia.” The curved cliffs in the image illustrate those scallops, found frequently in Utopia. Their formation is believed related to the sublimation of underground ice, changing directly from ice to gas. The theories of this process however are somewhat uncertain at this time.

What stuck me about the image were the north-south oriented cracks. They extend through the full image, all oriented in the same direction. I haven’t the faintest idea what caused them, but they are intriguing, are they not?

This terrain is also different than most Utopia Planitia images I have previously posted. Most look squishy and blobby and distorted, suggesting the presence of soft slush and underground ice. This image instead suggests hard bedrock, even though it is farther north than the previous images and should thus be expected to have more ice underground. Quite mysterious.

I suspect the ice is here, but is simply not made obvious by any surface event. Then again, who knows? The geology of Mars is definitely not obvious, no matter how obvious it sometimes seems.

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Curiosity captures a dust devil

11:33 am

During its recent and last several-week-long drilling effort in the clay unit in Gale Crater, the rover Curiosity was also able to luckily capture the passing of a nearby dust devil.

It’s almost summer in Gale crater, which puts us in a period of strong surface heating that lasts from early spring through mid-summer. Stronger surface heating tends to produce stronger convection and convective vortices, which consist of fast winds whipping around low pressure cores. If those vortices are strong enough, they can raise dust from the surface and become visible as “dust devils” that we can image with our cameras. The animated GIF shows a dust devil movie we took with Navcam on Sol 2847, covering a period of about five minutes. We often have to process these images, by enhancing what’s changed between them, before dust devils clearly show up. But this dust devil was so impressive that – if you look closely! – you can just see it moving to the right, at the border between the darker and lighter slopes, even in the raw images.

I have embedded the movie below the fold. The dust devil looks like a ghostly white tower moving from the left to the right just above the darkest band of landscape cutting across the middle of the image.
» Read more

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NASA’s first Orbiting Geophysical Observatory to burn up in atmosphere

11:11 am

The first of six Orbiting Geophysical Observatories, dubbed OGO-1, is set to to burn up in the atmosphere sometime in the next week.

Launched September 5, 1964, OGO-1 operated until 1969. It along with the five later OGO satellites were designed to study the Earth’s magnetic field as well as the Van Allen Belts across a solar minimum and maximum. Together they proved the magnetosphere was homogeneous, somewhat the same wherever data was obtained.

As the first such observatory, the spacecraft was also a technology test. Thus, the failure of its attitude control system, preventing about half its instruments from gathering data, was not really a failure. It laid the groundwork for all such research satellites to follow over the next half century.

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More glaciers and eroding gullies on Mars

2:51 pm

Crater with gullies and glacial fill
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, shows the interior south-facing rim of a small crater in the southern cratered highlands of Mars. Taken on May 30, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), the image release is merely labeled “Gullied Slope”. The photo was taken as part of regular monitoring of these gullies since 2011 to see if they change from season to season. The 2011 image was captioned by planetary scientist Alfred McEwen, who wrote the following about the gullies:

These are erosional features with depositional fans. Some of the gully fans have a bluish color: these are probably quite recent deposits, less than a few tens of years old.

Since they were considered so very young, it makes great sense to look at them frequently. In making a quick comparison between the 2011 and 2020 images however I could not spot any changes, but that might be because the versions I downloaded are not at the fullest resolution.

This crater, at 39 degrees south latitude, is also worthwhile because its floor appears covered with glacial material, what scientists have dubbed concentric crater fill. As McEwen noted in his 2011 caption,

On the floor of the crater (bottom of this image) are ridges that likely formed from the flow of ice, perhaps a few million years ago.

Those glaciers, generally protected by thin layers of dust and debris, are considered inactive at this time in Martian geological history. The many ridges however hint at the many many cycles in the Martian climate, fluctuating between periods when these mid-latitude glaciers were growing while the polar ice caps were shrinking, and periods when the mid-latitude glaciers were shrinking while the polar ice caps were growing.

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Hubble maps giant gas halo around Andromeda

11:38 am

Astronomers using the Hubble Space Telescope’s ability to observe in ultraviolet wavelengths have now mapped the giant halo of gas that surrounds the Andromeda galaxy 2.5 million light years away.

The work found that the halo appears to have both an inner and outer shell.

“We find the inner shell that extends to about a half million light-years is far more complex and dynamic,” explained study leader Nicolas Lehner of the University of Notre Dame in Indiana. “The outer shell is smoother and hotter. This difference is a likely result from the impact of supernova activity in the galaxy’s disk more directly affecting the inner halo.”

A signature of this activity is the team’s discovery of a large amount of heavy elements in the gaseous halo of Andromeda. Heavier elements are cooked up in the interiors of stars and then ejected into space—sometimes violently as a star dies. The halo is then contaminated with this material from stellar explosions.

The Andromeda galaxy, also known as M31, is a majestic spiral of perhaps as many as 1 trillion stars and comparable in size to our Milky Way. At a distance of 2.5 million light-years, it is so close to us that the galaxy appears as a cigar-shaped smudge of light high in the autumn sky. If its gaseous halo could be viewed with the naked eye, it would be about three times the width of the Big Dipper. This would easily be the biggest feature on the nighttime sky.

Though there is of course uncertainty here, this research is confirming earlier work, making its conclusions more robust.

A side note: Ultraviolet observations can only be done in space, as the atmosphere blocks it. Hubble I think is the only telescope in space right now with this capability. There used to be others, the most noteworthy of all being the International Ultraviolet Explorer, which functioned from 1978 to 1996 but was then decommissioned because neither NASA nor ESA were willing to fund its operation any longer.

No replacements have been launched because the budget for space astronomy has almost entirely been eaten by the overbudget and long delayed James Webb Space Telescope, with future budgets to be eaten similarly by the Roman.Space Telescope.

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UAE’S Hope Mars Orbiter images Mars

9:09 am

The United Arab Emirates’ (UAE) Hope Mars Orbiter has successfully imaged Mars for the first time using its star tracker camera, proving both that the spacecraft is on course and that its pointing capabilities are working as well .

“The Hope probe is officially 100 million km [60 million miles] into its journey to the Red Planet,” Mohammed bin Rashid Al Maktoum, prime minister of the UAE, wrote on Twitter on Monday (Aug. 24). “Mars, as demonstrated in the image captured by the probe’s star tracker, is ahead of us, leaving Saturn and Jupiter behind. The Hope probe is expected to arrive to Mars in February 2021.”

The star tracker is designed to keep Hope on course, telling the spacecraft precisely where it is. In addition, the probe carries a more traditional camera for use once it arrives at Mars and begins its science work.

Arrival in Mars orbit will take place in February ’21.

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Astronomers discover three merging supermassive black holes

9:03 am

Using telescopes on Mauna Kea in Hawaii, astronomers have discovered three different galaxies that have pairs of supermassive black holes at their center, with all three likely to merge at some point in the future.

First the scientists used the Subaru Telescope to survey more than 34,000 known quasars, high energy supermassive black holes.

The team identified 421 promising cases. However, there was still the chance many of these were not bona-fide dual quasars but rather chance projections such as starlight from our own galaxy. Confirmation required detailed analysis of the light from the candidates to search for definitive signs of two distinct quasars.

Using Keck Observatory’s Low Resolution Imaging Spectrometer (LRIS) and Gemini Observatory’s Near-Infrared Integral Field Spectrometer, Silverman and his team identified three dual quasars, two of which were previously unknown. Each object in the pair showed the signature of gas moving at thousands of kilometers per second under the influence of a supermassive black hole.

From this survey work they now tentatively estimate that only 0.3% of all known quasars are likely made up of a binary, which in turn gives them a rough estimate of how often galaxies with such supermassive black holes collide and merge. This in turn helps them develop theories on galaxy formation.

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What OSIRIS-REx will grab from the asteroid Bennu in October

6:16 pm

Closest view of Nightingale taken by OSIRIS-REx

On August 11th the spacecraft OSIRIS-REx did a sample grab-and-go rehearsal that put the spacecraft as close as 135 feet from the asteroid Bennu. During the rehearsal the spacecraft’s mapping camera (MapCam) snapped 22 images of the approach, showing the landing site, dubbed Nightingale, at the highest resolution yet.

From those images the science team created a movie. To the right is the closest image from that movie, lightened slightly and reduced to post here. It gives us the best view of the Nightingale landing site we will have prior to the October sample grab.

In essence, we are looking at the material that OSIRIS-REx will grab, though which particular rocks will be grabbed from this gravel pile are of course unknown. The spacecraft’s equipment is designed to capture pebbles smaller than 0.8 inches across. There are a good number of such rocks here, interspersed with a lot of larger rocks, including the several more than a foot across.

As I have noted previously, this landing site is about half the diameter of the landing sites the spacecraft was designed to touch down on. The rehearsal however gives us strong hope that OSIRIS-REx will be able to hit the bullseye. See this second movie, which shows the approach from two different cameras, with a wider context image provided to show how the spacecraft successfully hones in on its target.

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Wormlike glacier on Mars

9:30 am

Glacial flow in the mid-latitude southern cratered highlands
Click for full image.

Cool image time! The image to the right, cropped and reduced to post here, shows a very typical glacial-type feature found frequently in the mid-latitudes of Mars. Taken on May 23, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), it is labeled a “Lobate Flow Feature within Channel in Nereidum Montes.” Nereidum Montes is a rough mountainous region along the northwestern margin of Argyre Basin, the second largest impact basin on Mars, after Hellas Basin.

Scientists using Europe’s Mars Express orbiter have already found a great deal of glacial evidence in these mountains. I have also posted images of other glacial features on the north edge of Argyre. This image just reinforces that data.

This particular glacier however resembles the kind of glaciers one sees on Earth more than most Martian glaciers. As it meanders down its valley, large cracks form near its edges as friction slows their passage and drags them apart. In fact, the glacier itself might have very well carved the canyon. According to Dan Berman, senior scientist at the Planetary Science Institute in Arizona, who had requested this image,

While I can’t say for sure, the canyon was likely formed by a glacier. Whether or not the ice that remains today is part of that glacier, or one that formed later, is impossible to say.

» Read more

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The colors of Mars

1:07 pm

The different colors of Mars
Click for full image.

Actually today’s cool image tells us less about the real colors on Mars and much about the colors captured by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The photo on the right was taken on May 2, 2020, and shows a relatively featureless area to the east of 80-mile wide Byrd Crater in the high southern latitude of Mars.

The only major features seen on this photo are a series of rounded ridges that in the larger context map at the image site look almost like drainage hollows coming down from the crater’s rim about twenty miles away.

The colors, though exaggerated and not entirely as the eye would see them, still tell us something very real about the surface. As explained here [pdf]:

In spite of the variable level of color enhancement for the Extras products, we can make some generalizations to better understand what the stretched color images are showing. Dust (or indurated dust) is generally the reddest material present and looks reddish in the RGB color. … Coarser-grained materials (sand and rocks) are generally bluer … but also relatively dark, except where coated by dust. Frost and ice are also relatively blue, but bright, and often concentrated at the poles or on pole-facing slopes. Some bedrock is also relatively bright and blue, but not as much as frost or ice, and it has distinctive morphologies.

Thus, this photo is telling us that the lower areas are covered with dust (the red), while the rounded ridgelines are covered with coarser and bigger rocks. The brightest blue, which is facing towards the south pole, might also indicate frost or ice.
» Read more

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Report: Astronomy threatened by satellite constellations

11:31 am

A report issued today, resulting from a video conference of astronomers in July, has concluded that much of ground-based astronomy is threatened by the new large satellite constellations being launched by SpaceX, OneWeb, and others.

The astronomers’ report offers six solutions for solving the problem.

  • Launch fewer or no LEOsats. However impractical or unlikely, this is the only option identified that can achieve zero astronomical impact.
  • Deploy satellites at orbital altitudes no higher than ~600 km.
  • Darken satellites or use sunshades to shadow their reflective surfaces.
  • Control each satellite’s orientation in space to reflect less sunlight to Earth.
  • Minimize or eventually be able to eliminate the effect of satellite trails during the processing of astronomical images.
  • Make more accurate orbital information available for satellites so that observers can avoid pointing telescopes at them.

Notice what solution they don’t offer? Maybe astronomy should focus on building space-based telescopes, where the view would be clear, unimpeded by both the satellites and (much more importantly) the atmosphere.

In fact, the claim in the first solution above, that launching no satellites is “the only option identified that can achieve zero astronomical impact” is intellectually dishonest. All astronomers have to do is get their observatories into space, something that is very doable and affordable with today’s cheaper launch capabilities and technology. In space the impact of the satellites will once again be zero. And they will have the added benefit of getting outside the atmosphere, which by the way is actually a bigger limitation to observations than any satellite constellation.

It seems to me that this report was written by the faction of astronomers who make their living building big ground-based telescopes. Rather than think of solutions, they want to protect their turf by attacking the achievements of others.

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Hubble photographs Comet NEOWISE

12:38 pm

Comet NEOWISE, photographed by the Hubble Space Telescope
Click for full image.

Using the Hubble Space Telescope, astronomers have obtained close-up images of Comet NEOWISE after it had survived its closest approach to the Sun. The photo to the right, cropped and reduced to post here, is one of Hubble’s two images.

Comets often break apart due to thermal and gravitational stresses at such close encounters, but Hubble’s view suggests that NEOWISE’s solid nucleus stayed intact. This heart of the comet is too small to be seen directly by Hubble. The ball of ice may be no more than 4.8 kilometres across. But the Hubble image does captures a portion of the vast cloud of gas and dust enveloping the nucleus, which measures about 18 000 kilometres across in this image.

Hubble’s observation also resolves a pair of jets from the nucleus shooting out in opposite directions. They emerge from the comet’s core as cones of dust and gas, and then are curved into broader fan-like structures by the rotation of the nucleus. Jets are the result of ice sublimating beneath the surface with the resulting dust/gas being squeezed out at high velocity.

Below the fold is a six-second movie made of Hubble’s two images, showing how the jets changed over a three hour time period on August 8th.
» Read more

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Mars: On the floor of Valles Marineris

11:50 am

Strange flow (?) on floor of Valles Marineris
Click for full image.

Cool image time! The image to the right, rotated and cropped to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on May 14, 2020, and shows a very strange bright outcrop on the floor of Valles Marineris, the largest canyon on both Mars and in the entire solar system.

MRO has photographed this spot a few times since 2007. The first image was posted with a detailed caption by Colin Dundas of the U.S. Geological Survey’s Astrogeology Science Center in Arizona, who described the feature like so:

Most of the material is light and shows many small scarps or benches. In places these appear to indicate boundaries between layers, but they are often discontinuous. The light material is buried by a thin mantle of dark material in places; the dark material is from other rock layers—possibly those above the outcrop—and has fallen or been blown over the light rock.

Near the top of the outcrop, there is a distinctive layer that appears as a dark band at low resolution. At the full resolution of HiRISE, this appears to be a layer breaking up into angular boulders, indicating different rock properties than the underlying light rock. There does appear to be some light material above this layer, suggesting that the process that deposited the light material continued for some time.

Dundas also added that the lighter material is theorized to have “formed by a variety of processes. Proposed deposition mechanisms for light-toned sediments on Mars include those from rivers or lakes, volcanic ash or wind-blown sand or dust.”

Since this lighter colored outcrop has remained as bright as it has now for more than six Martian years, I doubt it is brighter because of the surface deposit of ash, sand, or dust (though it might be made of these materials which have now become hardened). My guess is that the brightness is inherent to the outcrop. Moreover, note the plateau to the southwest. Its rim is cut sharply, suggesting erosion revealed this outcrop, and that the outcrop is made of more resistant material.

The overview map provides some context that also might help explain the geology at this location.
» Read more

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Tests this weekend to pinpoint slow leak on ISS

1:08 pm

The astronauts this weekend will shut all the hatches between different modules on ISS so that ground controllers can try to pinpoint the location of a long term slow air leak.

This leak was first spotted in September 2019, when there were “indications of a slight increase above the standard air leak rate,” NASA said in the statement. “Because of routine station operations like spacewalks and spacecraft arrivals and departures, it took time to gather enough data to characterize those measurements. That rate has slightly increased, so the teams are working a plan to isolate, identify and potentially repair the source.”

While the leak rate is higher than usual, it is still within specifications for the station and poses no immediate danger to the crew, NASA officials emphasized. Astronauts also deal with leak simulations during training for their stays on the space station, which typically are about six months long.

The weekend test will allow them to identify where the leak is located. They will then be better able to find it, and mitigate it.

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Movie of OSIRIS-REx’s last rehearsal before sample grab

3:53 pm

Closest point to Nighingale landing site during OSIRIS-REx's last rehearsal
Click image for full movie.

The OSIRIS-REx science team has released a movie made by the spacecraft’s navigation camera during its August 11th final rehearsal prior to the planned sample grab-and-go now set for October.

The image to the right is a capture of one image when the spacecraft was closest to the asteroid, about 131 feet above the surface. The target landing site, dubbed Nightingale, is the somewhat smooth area near the top half of the frame.

These images were captured over a three-hour period – the imaging sequence begins approximately one hour after the orbit departure maneuver and ends approximately two minutes after the back-away burn. In the middle of the sequence, the spacecraft slews, or rotates, so that NavCam 2 looks away from Bennu, toward space. Shortly after, it performs a final slew to point the camera (and the sampling arm) toward the surface again. Near the end of the sequence, site Nightingale comes into view at the top of the frame. The large, tall boulder situated on the crater’s rim (upper left) is 43 feet (13 meters) on its longest axis. The sequence was created using nearly 300 images taken by the spacecraft’s NavCam 2 camera.

Nightingale might be their best choice, but it remains about half the size they had originally wanted for their grab-and-go site, with far too many objects larger than planned. They designed the grab-and-go equipment to catch objects smaller than 0.8 inches. Little at this location, or on the entire surface of Bennu, is that small. The asteroid is truly a pile of gravel, with no dust.

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Hope completes first course correction on trip to Mars

3:24 pm

The new colonial movement: The United Arab Emirates’ (UAE) Mars Hope orbiter has successfully completed its first course correction on its journey to Mars.

The success of this maneuver is a big deal, as it appears it was controlled from the UAE’s control center by its engineers. Up to now this project has mostly been a joint U.S/UAE project, launched by Japan, with U.S. universities doing the heavy lifting while training UAE personnel. Now the UAE engineers are in charge, and so they have to get it right.

They have another half dozen course corrections scheduled before arrival in February 2021, when the spacecraft will have its big maneuver, entering Martian orbit.

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Majestic dunes on Mars

11:26 am

Beautiful dunes on Mars
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 on May 10, 2020, and shows the dune field inside a large unnamed sixty-mile-wide crater in the highlands of Mars.

Scientists have been using MRO to monitor this site to track both dust devils and dune changes since at least 2009. In 2009 the focus was on the numerous dust devil tracks, and in fact I posted in March 2020 a comparison of an earlier image with a more recent picture, showing how the earlier tracks had vanished in recent pictures, probably wiped clean by the global dust storm in 2018.

This time however I am less interested in the science, which I covered in detail in that previous post, but in the beauty of these dunes. They are large and majestic, and the color strip tells us that they exhibit striking colors of green, gold, and tan. Is there a place on Earth with dunes of such colors? If so, it is rare.

Make sure you click on the image to see the full resolution photograph. It is even more breath-taking.

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Tiny asteroid sets record for closest fly-by of Earth

9:10 am

Astronomers using the robotic Zwicky Transient Facility (ZTF) at the Palomar Observatory in California on August 16 spotted a tiny asteroid just after it had zipped past the Earth at a distance of only 1,830 miles, the closest any asteroid has ever been seen to do so without hitting the ground.

Asteroid 2020 QG is about 10 to 20 feet (3 to 6 meters) across, or roughly the size of an SUV, so it was not big enough to do any damage even if it had been pointed at Earth; instead, it would have burned up in our planet’s atmosphere.

“The asteroid flew close enough to Earth that Earth’s gravity significantly changed its orbit,” says ZTF co-investigator Tom Prince, the Ira S. Bowen Professor of Physics at Caltech and a senior research scientist at JPL, which Caltech manages for NASA. Asteroids of this size that fly roughly as close to Earth as 2020 QG do occur about once a year or less, but many of them are never detected.

The ability to spot these things is continuing to improve, though it does not appear they have yet obtained enough information to predict 2020 QG’s full orbit, or when or if it will return.

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Mars: A small volcano at the base of a big volcano

1:31 pm

Volcanic vent near Pavonis Mons
Click for full image.

Today’s cool image is of a recent high resolution image taken on May 30, 2020 by Mars Reconnaissance Orbiter (MRO) of what they label as a volcanic vent near Pavonis Mons, the middle giant volcano in the string of three that sit between Olympus Mons, the biggest Martian volcano in the solar system, and Valles Marineris, the biggest canyon in the solar system.

MRO took a previous picture of this vent back in 2010, when they labeled it instead a “small volcano.” Both labels are essentially correct. The two depressions here clearly were a vent for lava at some point in the past. The depressions also fit the definition of a small volcano, as they sit at a high point with two rills flowing down from them. In some ways they could be considered small calderas at the top of a volcano.
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