Tag: science

Fractured and collapsed Martian crater floor

4:06 pm

Fractured and collapse Martian crater floor
Click for full image.

Time for some puzzling Martian geology. The image on the right, rotated, cropped, and reduced to post here, comes from the Mars Reconnaissance Orbiter (MRO) high resolution archive, and shows a strangely collapsed and fractured crater floor. In fact, like a number of other Martian craters, rather than having a central peak, the center of the crater floor, shown at the image’s center right, seems depressed.

The crater is located in a region dubbed the Cerberus Plains, in a hilly subregion called Tartarus Colles. Of the transition zone between the northern lowlands and the southern highlands these plains comprise the second largest region.

Being in the transition zone I would guess that the geology here is strongly influenced by the ebb and flow of the slowly retreating intermittent ocean that is thought to have once existed in the nearby lowlands. As water came and went, it created a variety of shoreline features scattered about, but not in a single sharp line as we would expect on Earth. Think more like tidal pools, where in some areas water gets trapped and left behind only to sublimate away at at later time.

We can see some hints of these processes in the images of the floors of two other craters that I have previously highlighted, here and here.

With this geological overview in mind, the broken plates here remind me of features I’ve seen in caves. Mud gets washed into a passage, partly filling it. Over time a gentle water flow over the surface of the mud deposits a crust of calcite flowstone on top of the mud. Should the water flow suddenly increase, it will wash out the mud below the crust. If the crust is not very strong or thick, it will crack into pieces as it falls, and thus resemble what we see here in this Martian crater.

There are cases where the crust becomes thick enough to remain standing, which produces some spectacular hanging calcite draperies that seem to defy explanation.

The collapse in the center of the crater is more puzzling, but suggests, based on comparable-looking Earth geology, that any perched water in this canyon might have actually drained out through underground drainage, accessed through the depression.

Be warned: All my explanations above are based on what exists on Earth, and Mars is very different from Earth. The lower gravity, colder temperatures, and different chemistry guarantee that the geological processes there will not be identical. We start by using what we know here, but recognize that we need to learn more about Mars to truly understand what goes on there.

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The temperature on Phobos

3:04 pm

The temperature on Phobos
Click for full image.

The Mars Odyssey science team today released false color images of the Martian Moon Phobos showing the temperature range that the spacecraft has detected, shown above in a reduced form.

The April 24, 2019 image is the first time Mars Odyssey had gotten a full moon look at the Moon. Not surprisingly, the hottest spots on the surface are at the center, at noon, with it getting cooler as one gets to the outer edges near dawn and dusk and at the poles.

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The temperature on Bennu

9:22 am

The OSIRIS-REx science team have released a short movie, compiled from data obtained in November 2018 as the spacecraft was first approaching the asteroid Bennu, that shows the dayside surface temperature and how it changes as the asteroid rotates.

I have embedded the movie below the fold.

Within a distance of only about 850 feet the temperature rises more than 270 degrees, from -99.67 °F to 170.33 °F. This change also occurs at every spot as the asteroid rotates. At dawn it will be that cold, and by noon it will be that hot.
» Read more

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Sunspot update April 2019: Not quite minimum

9:24 am

Time for the monthly sunspot update: NOAA yesterday released its the monthly update for the Sun’s sunspot cycle, adding sunspot activity for April 2019 to its graph. As I do every month, I have annotated that graph to give it some context and am posting it below.

While the Sun is clearly at the beginning of what might be an extended or very extended solar minimum, the continuing uptick in activity in both March and April illustrates that we have still not arrived at full minimum.

April 2019 sunspot activity

The graph above has been modified to show the predictions of the solar science community for the previous solar maximum. The green curves show the community’s two original predictions from April 2007, with half the scientists predicting a very strong maximum and half predicting a weak one. The red curve is their revised May 2009 prediction, extended in November 2018 four years into the future.

As the Sun ramps down to minimum it will have months where there is no activity, as happened in February 2019, and months, such as in March and April, where more sunspots appear.

Eventually the quiet months will become dominate, and soon thereafter, when activity increases again (assuming it does), the solar science community will then announce the date of true minimum.

We are not there. Normally it can take a year or more for the Sun to settle down. If activity declines as indicated by the red curve, it could take as long four years, which would be a record-long minimum. The difference will tell us whether the eleven-year solar cycle is continuing, or the Sun is heading into a grand minimum, with no significant sunspots for decades.

And as I have said repeatedly in the past five years, a grand minimum could significantly impact the global climate, cooling it. Or not. It is that unknown that will be answered should a grand minimum occur. Circumstantial data suggests an inactive Sun cools the planet, and the arrival of a new grand minimum will allow scientists to confirm or refute that circumstantial data.

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Bennu from two miles

9:02 am

Bennu from two miles
Click for full image.

In late March OSIRIS-REx completed its fourth fly-by of the asteroid Bennu. The image on the right, cropped and reduced to post here, was taken when the spacecraft was only 2.1 miles above the surface. If you were standing among these large boulders, we could easily see you.

The image itself shows the asteroid’s southern limb, and thus the shadows are accentuated. This makes it easier to see surface details. Though it is clear once again that Bennu is a pile of boulders and rocks cemented together and floating in space, the photograph also shows that it also has areas where the material is either much larger or fused together more solidly, as shown by the more massive sections in the left center of this picture. We might be looking a very large boulders peeking up from below the surface, or possibly this is the hint of some real bedrock.

The OSIRIS-REx team is continuing the spacecraft’s survey phase, gathering high resolution images in order to compile a detailed map of the surface, prior to planning the touch-and-go sample grab.

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More gravitational waves detected

9:47 am

Using the LIGO and Virgo gravitational wave telescopes astronomers have detected two more gravitational waves.

On April 25, 2019, one of the twin LIGO instruments and the Virgo detector observed a candidate signal which – if confirmed – would be the first binary neutron star merger during the third observation run, which began on April 1. A second candidate signal was seen on April 26, which – if confirmed – could be a never-observed-before collision of a neutron star with a black hole. The latter candidate was observed by both LIGO instruments and the Virgo detector. Dozens of telescopes on the Earth and in space are searching for electromagnetic or astro-particle counterparts. No identification with an electromagnetic transient signal nor a host galaxy has been made to date for either candidate.

The resolution of LIGO and VIRGO are somewhat limited, so other telescopes have to scan a very large part of the sky to spot a counterpart. It is therefore likely that it will be years before the first counterpart event is identified. When it is however it will tell us how far away the event was and confirm what kind of event it was. Right now, they are only making educated guesses.

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Satellites map out Earth’s Great Whirl

8:56 am

Using more than two decades of satellite data scientists have mapped out the yearly evolution of the
Great Whirl, a gigantic weather formation that routinely forms off the coast of Somalia each year, lasts for more than half the year, and is closely linked to India’s annual monsoon season.

Using 23 years of satellite data, the new findings show the Great Whirl is larger and longer-lived than scientists previously thought. At its peak, the giant whirlpool is, on average, 275,000 square kilometers (106,000 square miles) in area and persists for about 200 days out of the year.

More than being just a curiosity, the Great Whirl is closely connected to the monsoon that drives the rainy season in India. Monsoon rains fuel India’s $2 trillion agricultural economy, but how much rain falls each year is notoriously difficult to forecast. If researchers can use their new method to discern a pattern in the Great Whirl’s formation, they might be able to better predict when India will have a very dry or very wet season compared to the average.

Below the fold is a short video showing the Whirl’s behavior during 2000. It appears that the Great Whirl is an atmospheric eddy formed by the prevailing east winds as they hit the coast of Somalia.
» Read more

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X-37B passes 600 days in orbit

8:44 am

One of the Air Force’s two X-37B reusable mini-shuttles has now passed 600 days in orbit.

At this moment this is third longest X-37B mission. However, if the mission lasts four more months it will become the longest.

The article states that it is “unclear” what the mission’s overall purpose is, though we do know that some onboard experiments are testing the ability of some technology to function for long periods in space. I suspect that the spacecraft itself is testing this. When it returns they will look at it closely to see if its design was sufficient for it to do long multi-year missions and then go back to do it again. Moreover, knowing how to build such a craft is essential for building interplanetary spaceship that carry humans to and from the planets.

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Lunar eclipse meteorite hit the Moon at almost 38,000 mph

10:33 am

By analyzing the data obtained of the meteorite impact that hit the Moon during the January 21 lunar eclipse, astronomers now estimate it crashed into the surface at almost 38,000 miles per hour and would have produced a crater about 50 feet across.

They also estimate that the meteorite itself had a mass of about 100 pounds with a diameter of between one to two feet.

The new crater itself has not yet been spotted, and probably can only be photographed with the high resolution camera on Lunar Reconnaissance Orbiter (LRO). I expect the LRO science team has already scheduled observations for this location. It will be interesting to see if the actual crater corresponds to the estimates of these astronomers.

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New Hubble data baffles cosmologists about universe’s expansion rate

10:15 am

The uncertainty of science: New and very firm data from the Hubble Space Telescope on the universe’s expansion rate conflicts with just-as-firm data obtained by Europe’s Planck astronomical probe.

According to Planck, the present universe should be expanding at a rate of 67 kilometers per second per megaparsec. According to Hubble, the actual expansion rate is 74 kilometers per second per megaparsec.

And according to the scientists involved, both data sets are reliable and trustworthy, leaving them baffled at the difference.

“This is not just two experiments disagreeing,” explained [lead researcher and Nobel laureate Adam Riess of the Space Telescope Science Institute (STScI) and Johns Hopkins University, in Baltimore, Maryland.] “We are measuring something fundamentally different. One is a measurement of how fast the universe is expanding today, as we see it. The other is a prediction based on the physics of the early universe and on measurements of how fast it ought to be expanding. If these values don’t agree, there becomes a very strong likelihood that we’re missing something in the cosmological model that connects the two eras.”

Ya think? Any cosmologist who claims we really understand what is going on, based on our present fragile and very limited knowledge, is either fooling him or herself or is trying to fool us.

I should note that there seems to be an effort, based on the press release above as well as this second one, to downplay the amount of uncertainties that exist in this cosmological work. Both releases fail to note that when scientists announced their first expansion rate estimate from Hubble’s first data back in 1995, those scientists claimed with absolute certainty that the expansion rate was 80 kilometers per second per megaparsec. At the time some scientists, led by the late Allan Sandage of the Carnegie Observatory, disputed this high number, claiming the number could be as low as 50. Some even said it could be as low as 30 kilometers. Sandage especially found himself poo-pooed by the cosmological community for disputing that the 80 number pushed by Hubble’s scientists in 1995.

In the end, the Hubble scientists in 1995 were closer to today’s Hubble number than Sandage, but his estimate was not wrong by that much more, and he was right when he said the number had to be lower. Either way, Hubble’s modern estimate of 74 for the present expansion rate is very well constrained, and is a far more trustworthy number than previous estimates.

However, do we know with any reliability what the expansion rate was billions of years ago? No. Cosmologists think it was faster, based on supernovae data, which is where the theory of dark energy comes from. It is also where Planck’s predictions come from.

That early expansion rate, however, is based on such tentative data, containing so many assumptions and such large margins of error, that no serious scientist should take it too seriously. It suggests things, but it certainly doesn’t confirm them.

This is why their faith in the numbers derived from Planck puzzles me. It is based on a “prediction,” as Riess admits in the quote above, which means it is based on a theoretical model. It is also based on that very tentative early supernovae data, which makes it very suspect to me.

The Hubble data is real data, obtained by looking at nearby stars in a very precise matter. Its margin of error is very small. It contains only a few assumptions, mostly involving our understanding of the Cepheid variable stars that Hubble observed. While skepticism is always called for, trusting this new Hubble data more is perfectly reasonable.

In the end, to really solve this conflict will require better data from the early universe. Unfortunately, that is not something that will be easy to get.

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Hayabusa-2 confirms man-made crater on Ryugu

8:53 am

In a planned fly-over of Ryugu yesterday Hayabusa-2 took its first direct images of the location where it had fired an explosive projectile and thus confirmed the creation of a man-made crater by that projectile.

“The asteroid’s terrain has clearly been altered,” said Yuichi Tsuda, an associate professor at the Japan Aerospace Exploration Agency.

Hayabusa2, which began its descent toward the asteroid Wednesday afternoon, captured images of its surface to determine the existence of the crater after it successfully shot a metal projectile at Ryugu on April 5 in an experiment deemed the first of its kind.

According to the JAXA, the probe photographed the area hit by the projectile from a distance of 1.7 km. The agency compared images of the asteroid’s surface before and after the shooting of the projectile to determine the presence of a man-made crater.

They have not yet released any of these images. They will use them however for planning a touchdown and sample grab within this crater in next few months.

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Another spectacular landslide found on Mars

1:25 pm

Landslide in Hydraotes Chaos
Click for full image.

Cool image time! In perusing the April image release from the high resolution camera of Mars Reconnaissance Orbiter (MRO), I came across the image above, cropped and reduced to post here, of the discovery of another landslide within Hydraotes Chaos, one of the largest regions of chaos terrain on Mars. The image above was taken on February 9, 2019, and has since been followed up with a second image to create a stereo pair.

This is not the first landslide found in Hydraotes Chaos. I highlighted a similar slide on March 11. Both today’s landslide as well as the previous one likely represent examples of gravitational collapses as shown in this science paper about Martian ground water. Some scientists have proposed that Hydraotes Chaos was once an inland sea, and as the water drained away the loss of its buoyancy is thought to cause this kind of landslide at the base of cliffs and crater rims.

The past presence of water also helps explain the soft muddy look of this landslide. When this collapse occurred the material was likely saturated with water. Today it is most likely quite dry and hardened, but when it flowed it flowed like wet mud. Its size, almost a mile long and a quarter mile across, speaks to Mars’s low gravity, which would allow for large singular collapses like this.

Hydraotes Chaos itself is probably one of the more spectacular places on Mars. It sits at the outlet to Marineris Valles, shown in the image below. This gigantic canyon, which would easily cover the entire U.S. if placed on Earth, was the largest drainage from the large volcanic Tharsis Bulge to the west, where Mars’s largest volcanoes are located.
» Read more

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First Marsquake recorded by InSight?

1:39 pm

The InSight science team has announced that they think they have detected their first Mars quake, though it was too small to provide much information about the Martian interior.

The Martian surface is extremely quiet, allowing SEIS, InSight’s specially designed seismometer, to pick up faint rumbles. In contrast, Earth’s surface is quivering constantly from seismic noise created by oceans and weather. An event of this size in Southern California would be lost among dozens of tiny crackles that occur every day.

“The Martian Sol 128 event is exciting because its size and longer duration fit the profile of moonquakes detected on the lunar surface during the Apollo missions,” said Lori Glaze, Planetary Science Division director at NASA Headquarters.

…Three other seismic signals occurred on March 14 (Sol 105), April 10 (Sol 132) and April 11 (Sol 133). Detected by SEIS’ more sensitive Very Broad Band sensors, these signals were even smaller than the Sol 128 event and more ambiguous in origin. The team will continue to study these events to try to determine their cause.

The data so far suggests is that Mars is far quieter than Earth geologically, but any conclusions at this point would be premature.

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UAE’s space agency declares its Mars probe almost ready for launch

9:08 am

The new colonial movement: The space agency of the United Arab Emirates (UAE) today announced that its 2020 Mars orbiter, dubbed Hope, is now 85% complete and on track for making its launch window.

The Probe has already entered an intensive testing phase to ensure its readiness before the launch date, with less than 500 days are remaining for the launch. It is planned to reach Mars by 2021, coinciding with the 50th anniversary of the founding of the UAE.

Several aspects related to the design, assembly of the structure, cameras and control have been verified. So far, the Probe’s systems and components, as well as its ability to communicate with the ground station have been checked by the team. The Probe has succeeded in all the tests it has been subject to so far, ahead of the five environmental tests to be conducted on the probe from June to December 2019.

While this is likely true, we must remain a bit skeptical. Though the link goes to a Reuters Arab news source, the story appears to be entirely a copy of the press release. I know this because five different Arabian news sources used the exact same language in their stories, apparently all copying from the same release.

Thus, we don’t have any independent press in the UAE looking at what is going on here. This could be true, but who knows?

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How last year’s global dust storm changed one spot on Mars

1:36 pm

One spot on the western flank of Olympus Mons, August 2017
Click for full image.

To the right is an image taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) back in August 2017, cropped, rotated, and reduced to post here. It shows a particular spot on the western slope of the giant volcano Olympus Mons. The uncaptioned image release is entitled “Dark and Possibly Stationary Ripples in Anomalous Terrain.” The image was probably taken as a follow-up to this 2009 image to see if the the dark patches near the peaks and mounds as well as the strange wavy bands of light and dark had changed in eight years. As of 2017 however little had changed. The patches in the 2009 image seem darker, but that is almost certainly due to the lower sun angle causing longer shadows.

The slope goes downhill to the left. The wavy bands are thought to be geological layers exposed by erosion. The cause of the dark patches remain unknown.

I stumbled upon these two early images because of a third new image of this location, taken in February 2019 and spotted by me during my review of April 2019 images downloaded from MRO. That uncaptioned new image was titled “Change Detection in Olympus Maculae.” Had scientists spotted some new volcanic activity at this spot? To find out I dug into the MRO archive at this location and found both the 2009 and 2017 images.

The 2019 image is below. It is cropped, rotated, and reduced to match exactly with the image above in order to highlight any changes that might have occurred.
» Read more

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Five exoplanets discovered with orbits from 15 to 40 years long

9:30 am

Twenty years of observations have now resulted in the discovery of five exoplanets with long solar orbits ranging from 15 to 40 years.

“As early as 1998, a planetary monitoring programme was set up and carried out scrupulously by the many … observers [using the EULER telescope belonging to Geneva University, Switzerland,] who took turns every two weeks in La Silla [Chile] for 20 years”, says Emily Rickman. The result is remarkable: five new planets have been discovered and the orbits of four others known have been precisely defined. All these planets have periods of revolution between 15.6 and 40.4 years, with masses ranging approximately from 3 to 27 times that of Jupiter. This study contributes to increasing the list of 26 planets with a rotation period greater than 15 years.

The press release is very poorly written. It does not explain how 21 years of observations pinpointed the orbit of an exoplanet of forty years. I suspect they have seen enough of the star’s wobble to extrapolate that orbit, but the press release should have explained this.

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Mercury’s core is solid

8:48 am

By comparing computer models with data gathered during the closest orbits of the Messenger spacecraft when it was in orbit around Mercury scientists have concluded that the planet’s inner core is solid like the Earth’s, though much larger than the Earth’s relative to the planet’s size.

Genova and his team put data from MESSENGER into a sophisticated computer program that allowed them to adjust parameters and figure out what the interior composition of Mercury must be like to match the way it spins and the way the spacecraft accelerated around it. The results showed that for the best match, Mercury must have a large, solid inner core. They estimated that the solid, iron core is about 1,260 miles (2,000 kilometers) wide and makes up about half of Mercury’s entire core (about 2,440 miles, or nearly 4,000 kilometers, wide). In contrast, Earth’s solid core is about 1,500 miles (2,400 kilometers) across, taking up a little more than a third of this planet’s entire core.

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All high resolution images from Rosetta now available

8:35 am

The Rosetta science team has now made available to the public all 70,000 images taken by the spacecraft’s high resolution camera.

Between 2014 and 2016, the scientific camera system OSIRIS onboard ESA’s Rosetta spacecraft captured almost 70000 images of comet 67P/Churyumov-Gerasimenko. They not only document the most extensive and demanding comet mission to date, but also show the duck-shaped body in all its facets. In a joint project with the Department of Information and Communication at Flensburg University of Applied Sciences, the Max Planck Institute for Solar System Research (MPS), head of the OSIRIS team, has now published all of these images. The OSIRIS Image Viewer is suited to the needs of both laymen and expert and offers quick and easy access to one of the greatest scientific treasures of recent years.

The Rosetta archive can be found here.

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Seasonal frost in a gully on Mars

12:32 pm

Frost in a gully on Mars
Click for full image.

Cool image time! The photo on the right, cropped, reduced, and brightened slightly to post here, was part of the April image release from the high resolution camera on Mars Reconnaissance Orbiter (MRO). According to the titled of this release, it purports to show visible frost on what looks like an avalanche debris slope on the rim of a large crater. The frost is the bright streaks on the upper left of the slope.

I wonder. During last month’s 50th Lunar and Planetary Science Conference in Texas, there was one paper that I reported on that showed something very similar to this, and proposed that white streaks like this in a gully were actually exposed snow/ice. They proposed that the snow/ice was normally covered by dust, and the white streaks were where the dust had blown away to reveal the ice below. This in turn would then sublimate into gas, which in turn would cause the gully avalanches over time.

Below is a close-up of the white streaks on this rim.
» Read more

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