Tag: science

Sunspot update May 2019: The long ramp down

12:18 pm

NOAA yesterday released its May update for the Sun’s sunspot cycle. The graph is posted below, annotated by me to give it some context.

The Sun in May continued to show the exact same amount of activity as it had shown for March and April. This steady uptick in sunspot activity once again shows that the ramp down to full solar minimum will be long and extended.

May 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.

That we are definitely ramping downward to minimum, even with the slight increase in the past three months, is shown by the fact that the Sun has shown no sunspots for the past fifteen days. In fact, all the activity shown in May comes from the first half of the month. This pattern is actually a reflection of the Sun’s 27-day rotation period. As I noted in my February 2017 update,

January’s activity however illustrated a statistical phenomenon that is typical of the sunspot count. That count is determined not by the numbers of sunspots on the entire surface of the Sun, but on the sunspots visible on the side of the Sun facing the Earth. Since it is not unusual for one face to be more active than the other, as we transition from maximum to minimum the sunspot counts will often show a more pronounced up-and-down curve reflecting this fact. Since the Sun’s day equals about 27 Earth days, this means that about every two weeks the active side will dominate our view until it rotates away and the inactive side reveals itself for two weeks.

In 2017 the number of spots were greater, so the period of inactivity was generally less. Now, it is not unusual for the Sun to be blank for weeks at a time. When it does become active, it is also not unusual for that activity to be confined to one hemisphere, so we get two weeks or less of activity, followed by two weeks or more of blankness.

So far there have been no sunspots in June. Expect that to continue for at least another week, when the more active hemisphere of the Sun returns to face us. I would not be surprise however if that other hemisphere arrives with its sunspots gone, so that the present streak of blankness continues unabated.

Meanwhile, solar scientists struggle to figure out what is going to happen next. Unlike climate scientists, who know as little about the climate, the solar science community admits to its ignorance about the Sun, and the uncertainty of its solar models.

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VLT snaps image of double asteroid zipping past Earth

9:04 am

Double asteroid imaged by VLT

The Very Large Telescope (VLT) in Chile was successfully able to photograph the double asteroid that flew past the Earth on May 25 at a distance of 3.2 million miles and a speed of 43 thousand miles per hour.

The left image on the right is the raw image, while the right image is their reconstruction after applying adaptive-optics (AO) to the raw image. From the press release:

Bin Yang, VLT astronomer, declared “When we saw the satellite in the AO-corrected images, we were extremely thrilled. At that moment, we felt that all the pain, all the efforts were worth it.” Mathias Jones, another VLT astronomer involved in these observations, elaborated on the difficulties. “During the observations the atmospheric conditions were a bit unstable. In addition, the asteroid was relatively faint and moving very fast in the sky, making these observations particularly challenging, and causing the AO system to crash several times. It was great to see our hard work pay off despite the difficulties!”

To put it mildly, that right image is a fantasy. Astronomers love to tout the wonders of adaptive optics, but no matter how good it might be, it still is garbage-in-garbage-out, a computer simulation based on their guess at what the object would look like if there was no atmosphere in the way. In this particular case, they are being especially fantastic, and guaranteed to be wrong. It is impossible for them to extrapolate such minute surface details from the fuzzy image on the left.

Still, getting an image of this asteroid as it zipped by at that speed using such a large telescope is an achievement, and bodes well for the use of ground-based astronomy of near Earth asteroids.

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Solar scientists struggle to predict the next sunspot cycle

9:10 am

Link here. This is a detailed article describing the meeting in March where the solar science community gathered to formulate its prediction for the next solar cycle.

What stands out about the meeting is the outright uncertainty the scientists have about any prediction they might make. It is very clear that they recognize that all their predictions, both in the past and now, are not based on any actual understanding the Sun’s magnetic processes that form sunspots and cause its activity cycles, but on superficial statistics and using the past visual behavior of the Sun to predict its future behavior.

“There’s not very much physics involved,” concedes panelist Rachel Howe of the University of Birmingham in the United Kingdom, who has been tasked with reviewing the mishmash of statistical models. “There’s not very much statistical sophistication either.”

Panelist Andrés Muñoz-Jaramillo of the Southwest Research Institute in Boulder agrees with Howe. “There is no connection whatsoever to solar physics,” he says in frustration. McIntosh, who by now has walked downstairs from his office and appears in the doorway, is blunter. “You’re trying to get rid of numerology?” he says, smirking.

The result, as I repeatedly note in my monthly sunspot updates, is that the last prediction failed, and that there is now great disagreement among these scientists about what will happen in the upcoming cycle.

[They] dutifully tabulate the estimates, and come up with a peak sunspot range: 95 to 130. This spells a weak cycle, but not notably so, and it’s marginally stronger than the past cycle. [They do] the same with the votes for the timing of minimum. The consensus is that it will come sometime between July 2019 and September 2020. Maximum will follow sometime between 2023 and 2026.

The range of predictions here is so great that essentially it shows that there really is no consensus on what will happen, which also explains why the prediction has still not been added to NOAA’s monthly sunspot graph. For past cycles the Sun’s behavior was relatively consistent and reliable, making such statistical and superficial predictions reasonably successful.

The situation now is more elusive. For the past dozen or so years the Sun has not been behaving in a consistent or reliable manner. Thus, the next cycle might be stronger, it could be weak, or we might be heading into a grand minimum, with no sunspots for many decades. These scientists simply do not know, and without a proper understanding of the Sun’s dynamo and magnetic field, they cannot make a sunspot prediction that anyone can trust.

And so they wait and watch, as we all. The Sun will do what the Sun wants to do, and only from this we will maybe be able to finally begin to glean an understanding of why.

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Astronauts recover towel left on outside of ISS ten years ago

8:01 am

During a spacewalk this week Russian astronauts recovered a towel that had been left on the outside of ISS during an earlier spacewalk ten years ago.

The towel was originally meant to clean astronauts’ spacesuits during their work in outer space. It was left by a Russian cosmonaut about a decade ago. Mr Kononenko and Mr Ovchinin removed the towel from the station’s surface and placed it in a special container. It will be sent back to Earth and delivered to a group of experts for further examination.

Though unplanned, this towel will provide some good data on the ability of microorganism to survive in space. It almost certainly had such things within it when it was taken outside a decade ago, and the question now will be whether they survived or not, and their condition in either case.

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Rover update: May 30, 2019

12:28 pm

Summary: Curiosity confirms clay in the clay unit. Yutu-2 begins its sixth day on the far side of the Moon. Three other rovers move towards completion and launch.

For the updates in 2018 go here. For a full list of updates before February 8, 2018, go here.

Clouds over Gale Crater
Clouds over Gale Crater

Curiosity

For the overall context of Curiosity’s travels, see my March 2016 post, Pinpointing Curiosity’s location in Gale Crater.

Curiosity’s journey up the slopes of Mount Sharp in Gale Crater goes on! On the right is one of a number taken by the rover in the past week, showing water clouds drifting over Gale Crater.

These are likely water-ice clouds about 19 miles (31 kilometers) above the surface. They are also “noctilucent” clouds, meaning they are so high that they are still illuminated by the Sun, even when it’s night at Mars’ surface. Scientists can watch when light leaves the clouds and use this information to infer their altitude.

While these clouds teach us something about Martian weather, the big rover news this week was that the data obtained from the two drill holes taken in April show that the clay formation that Curiosity is presently traversing is definitely made of clay, and in fact the clay there has the highest concentration yet found by the rover.

This clay-enriched region, located on the side of lower Mount Sharp, stood out to NASA orbiters before Curiosity landed in 2012. Clay often forms in water, which is essential for life; Curiosity is exploring Mount Sharp to see if it had the conditions to support life billions of years ago. The rover’s mineralogy instrument, called CheMin (Chemistry and Mineralogy), provided the first analyses of rock samples drilled in the clay-bearing unit. CheMin also found very little hematite, an iron oxide mineral that was abundant just to the north, on Vera Rubin Ridge. [emphasis mine]

That two geological units adjacent to each other are so different is significant for geologists, because the difference points to two very different geological histories. The formation process for both the clay unit and Vera Rubin Ridge must have occurred at different times under very different conditions. Figuring out how that happened will be difficult, but once done it will tell us much about both Gale Crater and Mars itself.

With the success of their clay unit drilling campaign, the Curiosity science team has had the rover begin its trek back from the base of the cliff below Vera Rubin Ridge to its planned travel route up the mountain.

An updated description of that route was released by the Curiosity science team last week, while I was in Wales. Below is their image showing that route, with additional annotations by me and reduced to post here.
» Read more

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First movie of solar eclipse rediscovered

9:56 am

The first movie ever made of a solar eclipse, taken in 1900, has been rediscovered and restored.

The film was taken by British magician turned pioneering filmmaker Nevil Maskelyne on an expedition by the British Astronomical Association to North Carolina on 28 May, 1900. This was Maskelyne’s second attempt to capture a solar eclipse. In 1898 he travelled to India to photograph an eclipse where succeeded but the film can was stolen on his return journey home. It was not an easy feat to film. Maskelyne had to make a special telescopic adapter for his camera to capture the event. This is the only film by Maskelyne that we know to have survived.

I have embedded the movie below the fold.
» Read more

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Hayabusa-2 successfully places reference target at man-made crater

8:48 am

Close-up during Hayabusa-2's close approach

Hayabusa-2 has successfully dropped a small reference target at the man-made crater on Ryugu, getting within 10 meters of the surface.

The image to the right is the last image taken by the spacecraft’s navigation camera during the operation. Unfortunately, the science team did not provide any further information, such as the height from which this image was taken, nor the scale of the features. Based on the sequence of images, it clearly occurred at the moment of closest approach.

I have tried to see if I could pinpoint the crater in the image by comparing it to the planning image post here. Unfortunately, I have been unable to identify comparable features.

Either way with the successful placement of the reference target on the surface, they can now begin planning the sample grab touch-and-go at this location.

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The mysterious slope streaks of Mars

12:10 pm

Massive flow on Mars
A typical Martian slope streak.

The uncertainty of science: In the past decade or so scientists have documented in detail a number of features on the Martian surface that evolve or change over time. From the constantly changing poles to the tracks of dust devils to landslides to the appearance of seasonal frost, we have learned that Mars is far from a dead world. Things are happening there, and while they are not happening as quickly or with as much energy as found on Earth, geological changes are still occurring with regular frequency, and in ways that we do not yet understand.

Of the known changing features on Mars, two are especially puzzling. These are the two types of changing streaks on the slopes of Martian cliffs, dubbed recurring slope lineae (referred as RSLs by scientists) and slope streaks.

Lineae are seasonal, first appearing during the Martian summer to grow hundreds of feet long, and then to fade away with the arrival of winter. Their seasonal nature and appearance with the coming of warm temperatures suggests that water plays a part in their initiation, either from a seep of briny water or an avalanche of dust. Or a combination of both. The data however does not entirely fit these theories, and in fact is downright contradictory. Some studies (such as this one and this one) say that the seasonal lineae are caused by water. Other studies (such as this one and this one) say little or no water is involved in their seasonal formation.

The answer remains elusive, and might only be answered, if at all, when Curiosity takes a close look at two lineae in the coming years.

Slope streaks however are the focus of this post, as they are even more puzzling, and appear to possibly represent a phenomenon entirely unique to Mars. I became especially motivated to write about these mysterious ever newly appearing features when, in reviewing the May image release from the high resolution camera on Mars Reconnaissance Orbiter (MRO), I found four different uncaptioned images of slope streaks, all titled “Slope Stream Monitoring.” From this title it was clear that the MRO team was re-imaging each location to see if any change had occurred since an earlier image was taken. A quick look in the MRO archive found identical photographs for all four slope streak locations, taken from 2008 to 2012, and in all four cases, new streaks had appeared while older streaks had faded. You can see a side-by-side comparison of all four images below the fold.
» Read more

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NASA IG finds both Europa missions a mess

10:25 am

Our incompetent federal government: A report released today [pdf] by NASA’s inspector general has found that the management of the Europa Clipper orbiter and the later Europa lander missions, both mandated by Congress, are facing serious budget and schedule risks, despite being given more than three-quarters of a billion dollars more than requested.

Congress has taken a strong interest in the project and since fiscal year (FY) 2013 has appropriated about $2.04 billion to NASA for a Europa mission—$1.26 billion more than the Agency requested.

…Despite [this] robust early-stage funding, a series of significant developmental and personnel resource challenges place the Clipper’s current mission cost estimates and planned 2023 target launch at risk. In addition, although Congress directed NASA to use the SLS to launch the Clipper, it is unlikely to be available by the congressionally mandated 2023 date and therefore the Agency continues to maintain spacecraft capabilities to accommodate both the SLS and two commercial launch vehicles, the Delta IV Heavy and Falcon Heavy. [emphasis mine]

The lander meanwhile is in even worse shape, especially because its congressionally-mandated launch date on SLS in 2025 seems impossible.

It seems to me that this entire project could be the poster boy for the overall incompetence of our so-called “betters” in Washington, who in the past three decades have failed spectacularly in practically every major project they have undertaken. The project was mandated on NASA by Congress, led by former congressman John Culberson (R-Texas), who was then the chairman of the House subcommittee that was in charge of funding the agency. It was his pet project. Though the planetary science community were glad to have this mission, it was listed as their second priority in their 2011 decadal survey. Culberson made it first, and also made sure it got a lot of money, far more than NASA ever requested.

Despite this strong support, the inspector general has now found that the project is being badly mismanaged and faces budget overruns and scheduling problems. The scheduling problems partly result from the project’s bad management, but mostly because of Congress’s demand that the spacecraft fly on SLS. Our vaunted elected officials wanted to give that boondoggle (they own pet project) a mission, something it didn’t have, and Europa Clipper and Lander were therefore given that task.

The problem, as I have documented endlessly, is that SLS is woefully behind schedule. It appears it will likely not be ready for Europa Clipper’s launch window in 2023.

But hey, let’s give our federal government more responsibility and power! Let’s go socialist!

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Hayabusa-2 has begun approach to Ryugu

9:05 am

Ryugu during approach

Hayabusa-2 has begun its approach to the man-made impact site on Ryugu in order to drop a reflective reference target there in preparation for a later touch-and-go landing.

The link provides real time delivery of the images taken by the spacecraft’s navigation camera, released approximately once every thirty minutes. The image on the right, brightened slightly to post here, is the most recent image as I write this post.

The approach will take almost twenty-four hours, so viewing the changes at the link will be somewhat equivalent to watching paint dry. I suggest returning every few hours to see the closer images of the asteroid.

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Chang’e-4 and Yutu-2 wake up for sixth lunar day

8:29 am

China’s Chang’e-4 lander and Yutu-2 rover have been reactivated this week to begin observations during their sixth lunar day on the far side of the Moon.

According to the Chinese news source,

For the sixth lunar day, the lander’s neutron radiation detector and low-frequency radio detector will be restarted to conduct scientific tasks including particle radiation observation and low-frequency radio astronomical observation.

The rover’s panoramic camera, detection radar, infrared imaging spectrometer and neutral atom detector will be restarted during the sixth lunar day.

That’s about all we know. They have not released much information about the rover’s travels, nor have they released any detailed information about the data they have obtained.

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Scientists propose planetary orbital alignments cause the sunspot cycle

10:15 am

The uncertainty of science: Scientists today proposed a new model that says the orbital alignments of the planets, most especially Venus-Earth-Jupiter, act to initiate the eleven-year solar sunspot cycle.

As with the gravitational pull of the Moon causing tides on Earth, planets are able to displace the hot plasma on the Sun’s surface. Tidal forces are strongest when there is maximum Venus-Earth-Jupiter alignment; a constellation that occurs every 11.07 years. But the effect is too weak to significantly perturb the flow in the solar interior, which is why the temporal coincidence was long neglected. However, the HZDR researchers then found evidence of a potential indirect mechanism that may be able to influence the solar magnetic field via tidal forces: oscillations in the Tayler instability, a physical effect that, from a certain current, can change the behavior of a conductive liquid or of a plasma. Building on this concept, the scientists developed their first model in 2016; they have since advanced this model in their new study to present a more realistic scenario.

More details at the link. To put it mildly, this theory is far from proven. While they mention how it might also cause grand minimums and double-peaked maximums, they are somewhat vague in explaining this process. If valid, however, they should be able to use this model to predict future cycles, including the possible arrival of a new grand minimum in the coming decades.

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Future lunar colonies at Shackleton Crater at the Moon’s south pole

9:52 am

The rim of Shackleton Crater
Click for full image.

The Lunar Reconnaissance Orbiter (LRO) science team has released a new image of the rim of Shackleton Crater, reduced slightly in resolution to post here on the right. The Moon’s south pole is located on the crater’s rim near the top right of this image. As they note at the link, the interior of Shackleton never gets any sunlight, making it what scientists call a Permanently Shadowed Region (PSR), while a ridgeline running south to de Gerlache Crater gets sunlight 90% of the time.

An elevated ridge runs roughly between Shackleton and de Gerlache craters, and the relatively high elevation of this landscape means that some portions are illuminated up to 90% of the time, but nowhere is permanently illuminated. Future explorers could take advantage of this persistent illumination by setting up solar panels in several closely spaced locations providing nearly constant solar generated electricity.

The proximity to Permanently Shadowed Regions in and around Shackleton crater adds scientific value to this destination, as PSRs are often home to compounds such as water ice that are not found elsewhere on the Moon, but which contain clues to the history of of inner Solar System water and other volatile elements. A nearby, ready source of water-ice would also be of benefit to human surface activities, either as a consumable (air or water) or as spacecraft fuel.

Below is a more detailed map they provide showing this area, with the permanently shadowed regions shaded in blue. The green dot indicates the location of the south pole. The green arrows indicate regions in sunlight in the full image.

The region around Shackleton

Sadly, I expect we are looking at the locations of future Chinese and Indian lunar bases. Though the U.S. has done all the proper legwork to find out the exact locations to build a lunar base at Shackleton, our government has decided we will instead twiddle our thumbs in lunar orbit while other countries use our legwork to land and establish bases on the Moon itself.

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OSIRIS-REx moves into new science phase

9:01 am

The OSIRIS-REx science team has shifted the spacecraft’s operation into a new phase aimed at carefully mapping the surface of the asteroid Bennu in preparation for an eventual touch-and-go sample grab.

During Detailed Survey: Equatorial Stations phase, the spacecraft’s instruments will make the scientific observations needed to help the team home in on the best location on Bennu to collect a sample of regolith (loose surface material). To obtain these data, the spacecraft will execute a series of slews between Bennu’s north and south poles while taking observations from seven different stations above the equator. These data will be studied to understand the geology of Bennu. The spacecraft will also conduct searches for dust and gas plumes.

During this phase, planned to last through mid-June, they are asking for the public’s help in mapping the surface and its innumerable rocks.

For this effort, NASA is partnering with CosmoQuest, a project run out of the Planetary Science Institute that supports citizen science initiatives. Volunteers will perform the same tasks that planetary scientists do – measuring Bennu’s boulders and mapping its rocks and craters – through the use of a simple web interface. They will also mark other scientifically interesting features on the asteroid for further investigation.

The boulder mapping work involves a high degree of precision, but it is not difficult. The CosmoQuest mapping app requires a computer with a larger screen and a mouse or trackpad capable of making precise marks. To help volunteers get started, the CosmoQuest team provides an interactive tutorial, as well as additional user assistance through a Discord community and livestreaming sessions on Twitch.

Seems like fun!

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Hayabusa-2 aborts close-in drop of visual marker on Ryugu

3:09 pm

Japan’s asteroid probe Hayabusa-2 automatically aborted a planned drop of a visual markee on the asteroid Ryugu at the site where the probe created a crater in April.

Thursday’s mission was to observe the targeted area in detail and drop a marker from an altitude of 10 meters. But officials say the probe automatically suspended the operation after it descended to about 50 meters above the surface. It then headed toward its standby position of 20 kilometers above Ryugu. Hayabusa2 is designed to automatically abort its landing if it detected any irregularity. The agency is looking into the cause of the arrested descent.

Once the marker is eventually in place, they will use it for guidance during a a second touchdown to grab further samples, this time hopefully of material churned up by the explosion that created the crater.

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The floor of Marineris Valles

12:02 pm

Close-up of the floor of Marineris Valles

Larger view
Click for the full image.

To the right is small section cropped out of an image, taken by the high resolution camera of Mars Reconnaissance Orbiter (MRO) on March 30, 2019, of one very tiny area of the floor of the 2,500 mile long Marineris Valles, the biggest known canyon in the solar system.

Below this on the right is a larger section of the full image, with the white box showing the part covered by the top photograph. The general flow direction is to the east.

The photograph, uncaptioned, is titled “Terminus of Pitted Materials Emanating from Oudemans Crater.” Oudemans Crater is about 55 miles across and is located near the head of Marineris Valles to the east of the giant volcanic region dubbed the Tharsis Bulge. The meteorite that caused this crater is estimated to have been a little less than 3 miles in diameter. It is believed by some scientists that the impact heated up subsurface carbon dioxide permafrost which then explosively flooded down the Valles Marineris into the Northern Plains of Mars, pushing a lot of pulverized debris in front of it..

Instead of liquid water, what is stored underground on Mars is liquid CO2 and when a collapse occurs, this boils almost instantly and explosively to CO2 vapour, blasting the rock and regolith to dust, except for the most resistant fragments such as igneous rocks. The rest of the regolith is composed of dust and gravel, weakly cemented by water ice. On Mars, water is not a fluid, but behaves as a mineral in most situations. Grains of ice would be tumbled along in the cryogenic flows, and transported as passive solids just like quartz grains are transported as sand by rivers on Earth.

This theory, if correct, would eliminate the need for liquid water on the surface, and would explain many of the planet’s geological surface features.

Overview

The overview thumbnail to the left shows the location of both Oudemans Crater and this MRO image, indicated by the very tiny blue rectangle near the thumbnail’s center..

The “pitted materials” in the image’s title refers to that flowing avalanche of pulverized ice, rock, and dust, shown in the picture by the curved terraced cliffs descending to the east. This is where this material settled as it flowed eastward, pushed by that explosive CO2 flood.

You can see another example of this eastward flow in another MRO image taken just to the west. The canyon floor is pitted, confused, and rough, but there is an obvious flow trend to the east.

In fact, much of the floor of Marineris Valles that has been photographed at high resolution is similarly rugged. It will be a challenge to explore this place, especially because we have only imaged a small percentage at high resolution. There is much there that remains unseen and unknown.

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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.
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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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