Tag Archives: science

New Horizons completes another course correction before flyby

On December 2 New Horizons successfully completed another engine burn to refine its course for its January 1, 2019 flyby of the Kuiper Belt object Ultima Thule.

The maneuver was designed to keep New Horizons on track toward its ideal arrival time and closest distance to Ultima, just 2,200 miles (3,500 kilometers) at 12:33 a.m. EST on Jan. 1. At the time of the burn New Horizons was 4.03 billon miles (6.48 billion kilometers) from Earth and just 40 million miles (64 million kilometers) from Ultima – less than half the distance between Earth and the Sun. From that far away, the radio signals carrying data from the spacecraft needed six hours, at light speed, to reach home.

The team is analyzing whether to conduct up to three other course-correction maneuvers to home in on Ultima Thule.

The distance to Ultima Thule is still too much to produce detailed images. New Horizons however is going very fast, so in the coming three weeks this will change drastically, and for the better.


InSight tests its robot arm

InSight has unfolded its robot arm and is beginning to use it to photograph the surrounding area to figure out where to place the spacecraft’s ground-sensing instruments.

With a reach of nearly 6 feet (2 meters), the arm will be used to pick up science instruments from the lander’s deck, gently setting them on the Martian surface at Elysium Planitia, the lava plain where InSight touched down on Nov. 26.

But first, the arm will use its Instrument Deployment Camera, located on its elbow, to take photos of the terrain in front of the lander. These images will help mission team members determine where to set InSight’s seismometer and heat flow probe – the only instruments ever to be robotically placed on the surface of another planet.

They are proceeding carefully, so actually deployment might not occur for several months, just make everything goes well.


Sunspot update November 2018: Minimum continues

NOAA’s monthly update of the solar cycle, covering sunspot activity for November 2018, was released yesterday. As I have done every month since this website began in July 2011, I am posting it below, annotated to give it some context.

November 2018 sunspot activity

The graph above has been modified to show the predictions of the solar science community. 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.

As I have been expecting now for the last three months, NOAA has finally revised this graph to extend it past the end of 2018. The graph below is the graph from October, which follows the layout and design used since 2007. You can see the differences by comparing the two graphs. In extending the new graph to the end of 2022, they fortunately did not change the design significantly. However, because the new graph has a slightly different scale, I have stretched the green and red curves to make them fit properly. While I suspect the poor quality of the 2007 and 2009 predictions is one reason they do not include them on their graph, I think it essential to add them to better understand the limitations of the science.
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BepiColombo tests its ion engines

The joint European/Japanese mission BepiColombo has begun testing its ion engine thrusters for the first time in space as it heads to Mercury.

Testing took place during a unique window, in which BepiColombo remained in continuous view of ground-based antennas and communications between the spacecraft and those controlling it could be constantly maintained. This was the only chance to check in detail the functioning of this fundamental part of the spacecraft, as when routine firing begins in mid-December, the position of the spacecraft will mean its antennas will not be pointing at Earth, making it less visible to operators at mission control.

They have so far successfully tested two of the four engines.


Solar scientists: sunspot increase in next solar cycle

The uncertainty of science: Using new computer models, two solar scientists are now predicting that the next solar cycle will begin in about a year and will see an increase in sunspot activity, compared to the weak cycle just ending.

Their ensemble forecast surprisingly suggests it could even be stronger than the cycle which is just ending. They expect the next cycle to start rising in about a year following the end of the current sunspot cycle minimum and peak in 2024. Bhowmik and Nandi predict space environmental conditions over the next decade would be similar or slightly harsher compared to the last decade. They find no evidence of an impending disappearance of sunspot cycles and thus conclude that speculations of an imminent Sun-induced cooling of global climate is very unlikely.

Their conclusion is different than other predictions that are claiming a weak next cycle, or even the beginning of a grand minimum, with no suspots at all. Since an real understanding of the sunspot cycle remains elusive, and all these predictions rely on computer models, it is hard to say which will be right. The advantage this particular prediction has is that their model appears able to match what has happened for the past 100 years.

Stay tuned.


The vast southern highlands of Mars

Small section of Rocky Highlands

Rocky highlands

Cool image time! This week the Mars Reconnaissance Orbiter (MRO) science team made available its monthly release of new images taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The image above is just a small cropped section from one of those new images, released under the name “Rocky Highlands.” The image on the right is a cropped and reduced section of the full photograph, with the white box indicating the small section above. If you click on either you can see the full resolution uncropped photograph and explore its complex and rough terrain.

What should immediately strike you looking at the small inset section above is the difficulty anyone is going to have traversing this country. There are no flat areas. Every inch seems to be a broken and shattered collection of ridges, pits, craters, or rippled dunes. And the inset above is only a tiny representation of the entire image, all of which shows the same kind of badlands.

This forbidding place is located in the southern highlands of Mars, north of Hellas Basin and south of the transition zone that drops down to the northern lowland plains. The white cross on the map below indicates the image location, with green representing the transition zone, blue the northern plains, and red/orange the southern highlands..
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The bottom of Mars

Hellas Basin ripples

Cool image time! The photo on the right, cropped and reduced to post here, was taken by the high resolution camera of Mars Reconnaissance Orbiter (MRO) on May 2, 2018, and shows some very strange ripples and erosion features in one of the lowest elevation locations on Mars, inside Hellas Basin. If you click on the image you can see the full photograph, at full resolution. There are a lot of strange features here, so make sure you take a look at it. The ripples highlighted in the image are between what appear to be three lower basins, and seem to my eye to be ridges created as liquid ebbed and flowed in the basins, depositing material at the shoreline at repeatedly higher and lower levels.

hellas basin

This particular location is not only in Hellas Basin, but it is also located in the deepest part of Hellas, a curved valley located in the basin’s northwest quadrant, as shown by the darker areas in the overview image to the right. The red boxes are other MRO high resolution images, with the cross indicating where this image is located.

This is the bottom of Mars, what could be called its own Death Valley. The difference however is that unlike Death Valley, conditions here could be more amendable to life, as the lower elevation means the atmosphere is thicker. The ripples also suggest that liquid water might have once been here, a supposition supported by other low area images of Hellas Basin, most of which show a flattish dappled surface that to me resembles what one would think a dry seafloor bed would look like The image in this second link also shows what looks like ghost craters that over time became partly buried, something one would also expect to happen if they were at the bottom of a lake, though this could also happen over time on Mars with wind erosion and the movement of dust.

It is also possible that these features come from lava events, so please take my theorizing here with a great big grain of salt. At the same time, recent results have found evidence of paleo lakes scattered all along the eastern rim of the basin, reinforcing the possibility that these were water filled lakes once as well.

Nonetheless, the ripples in the first image above are truly fascinating, as it is clear that at the highest peaks erosion has ripped those peaks away, leaving behind a hollow shaped by the ripples themselves. These features remind me of some cave features I have seen, where mud gets piled but by water flow, and then is over time covered with a crust of harder calcite flowstone. Later, water then washes out the mud underneath, leaving the curved flowstone blanket hanging in the air.

Here in Hellas Basin it looks like something similar has happened, except that at these peaks the outside crust got broken away, allowing wind to slowly suck out the material underneath, leaving these ripple-shaped pits. Whether it was liquid water or lava that helped create these features, the geology left behind is both beautiful and intriguing. I wonder at the chemical make-up of the crust as well as the materials below. And I especially wonder if there is water sources buried within Hellas Basin.


OSIRIS-REx at Bennu

OSIRIS-REx has successfully completed its last maneuver engine burn to place it in proximity orbit around the asteroid Bennu.

The link takes you to the live NASA stream, which has been a bit hokey. This event is actually not that visually exciting, a bunch of engineers staring at computer screens awaiting data back from the spacecraft indicating that all has occurred as planned. In fact, some felt a bit staged, though the actual event was really happening.

The OSIRIS-REx team has released relatively little data so far, compared to most NASA missions. There will be a press conference in a week when they say they will release more information. I guess we will have to wait until then.

Update: the live stream has shifted to the docking of the manned Soyuz capsule at ISS, which is in itself a more riveting event than OSIRIS-REx’s last engine burn.


Four more gravitational wave detections

The uncertainty of science: The scientists running the LIGO gravitational wave detector have announced the detection of four more gravitational waves, bringing to eleven the total number so far observed.

During the first observing run O1, from September 12, 2015 to January 19, 2016, gravitational waves from three BBH mergers were detected. The second observing run, which lasted from November 30, 2016, to August 25, 2017, yielded a binary neutron star merger and seven additional binary black hole mergers, including the four new gravitational wave events being reported now. The new events are known as GW170729, GW170809, GW170818 and GW170823 based on the dates on which they were detected. With the detection of four additional BBH mergers the scientists learn more about the population of these binary systems in the universe and about the event rate for these types of coalescences.

The observed BBHs span a wide range of component masses, from 7.6 to 50.6 solar masses. The new event GW170729 is the most massive and distant gravitational-wave source ever observed. In this coalescence, which happened roughly 5 billion years ago, an equivalent energy of almost five solar masses was converted into gravitational radiation.

In two BBHs (GW151226 and GW170729) it is very likely that at least one of the merging black holes is spinning. One of the new events, GW170818, detected by the LIGO and Virgo observatories, was very precisely pinpointed in the sky. It is the best localized BBH to date: its position has been identified with a precision of 39 square degrees (195 times the apparent size of the full moon) in the northern celestial hemisphere. [emphasis mine]

The highlighted quote above illustrates the amount of uncertainty here. Though these appear to be gravitational waves, and have been confirmed in multiple ways, the data is very coarse, providing only a limited amount of basic information about each event. This limited information is still very valuable, and certainly advances our understanding of black holes and their formation, but it is important to recognize the limitations of that data.


Astronomers get best and earliest view of supernovae ever

Using ground-based telescopes as well as the space telescope Kepler astronomers have obtained their best and earliest view of a Type Ia supernova.

The supernova, named SN 2018oh, was brighter than expected over the first few days. The increased brightness is an indication that it slammed into a nearby companion star. This adds to the growing body of evidence that some, but not all, of these thermonuclear supernovae have a large companion star that triggers the explosion.

Las Cumbres Observatory (LCO), based in Goleta, California, is a global network of 21 robotic telescopes that obtained some of the best data characterizing the supernova in support of the NASA mission. Wenxiong Li, the lead author of one of three papers published today on the finding, was based at LCO when much of the research was underway. Five other LCO astronomers, who are affiliated with the University of California Santa Barbara (UCSB), also contributed to two of the papers.

Understanding the origins of Type Ia supernovae is critical because they are used as standard candles to map out distances in cosmology. They were used to discover Dark Energy, the mysterious force causing the universe to accelerate in its expansion. Astronomers have long known that a supernova is the explosion of a dense white dwarf star (A white dwarf has the mass of the sun, but only the radius of the Earth; one teaspoon of a white dwarf would weigh roughly 23000 pounds) What triggers the explosion is less well understood. One theory holds that the explosions are the merger of two white dwarf stars. Another is that the second star is not a white dwarf at all, but a normal-sized or even giant star that loses only some of its matter to the white dwarf to initiate the explosion. In this theory, the explosion then smashes into the surviving second star, causing the supernova to be exceedingly bright in its early hours.

Finding that Type Ia supernovae can be brighter than previously believed throws a wrench into the results that discovered dark energy, since those results made assumptions about the brightness and thus the distance of those supernovae. If the brightness of these supernovae are not as reliable as expected, they are also less of a standard candle for estimating distance.


More ice cliffs found on Mars!

Another ice cliff

In my review of the November image download from the high resolution camera on Mars Reconnaissance Orbiter (MRO), I am, as a cave explorer and cartographer, naturally attracted to any image with “pit” in the title. The image to the right, cropped, rotated and reduced to post here, was released with the title “Pit in Mid-Latitude Mantle”. That immediately caught my eye, and in looking at it I was at first unimpressed. The three apparent collapses are interesting in that they all have south-facing sharp cliffs, but other than that I wasn’t sure why they were of interest.

Then I took at look at this image’s location. It is somewhat far south on Mars, at latitude -60 degrees, sitting south of Hellas Basin, the deepest basin on Mars. This location is in the same general area where scientists announced in January the discovery of eight cliffs with visible exposed ice layers. The white horizontal bar below Hellas Basin on the map below and to the right shows the region where seven of those ice cliffs were located. To quote the January press release:

The location of known ice scarps on Mars

These eight scarps, with slopes as steep as 55 degrees, reveal new information about the internal layered structure of previously detected underground ice sheets in Mars’ middle latitudes.

The ice was likely deposited as snow long ago. The deposits are exposed in cross section as relatively pure water ice, capped by a layer one to two yards (or meters) thick of ice-cemented rock and dust. They hold clues about Mars’ climate history. They also may make frozen water more accessible than previously thought to future robotic or human exploration missions.

Researchers who located and studied the scarp sites with the High Resolution Imaging Science Experiment (HiRISE) camera on MRO reported the findings today in the journal Science. The sites are in both northern and southern hemispheres of Mars, at latitudes from about 55 to 58 degrees, equivalent on Earth to Scotland or the tip of South America. “There is shallow ground ice under roughly a third of the Martian surface, which records the recent history of Mars,” said the study’s lead author, Colin Dundas of the U.S. Geological Survey’s Astrogeology Science Center in Flagstaff, Arizona. “What we’ve seen here are cross-sections through the ice that give us a 3-D view with more detail than ever before.”

In an email correspondence today with Dr. Dundas, he confirmed that the image to the right was of ice cliffs not included in the January paper. The image was a follow-up of an earlier MRO image and was taken to confirm the ice cliff’s existence.

What I noticed in reviewing the January paper was that these three new ice scarps were actually outside the white bar on the map above, located at -60.7 degrees latitude, 83.5 degrees longitude.
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Analysis of InSight’s landing site

Link here. It appears they landed within a small crater filled with sand.

InSight landed in what’s called a hollow, a crater that has been filled in with soil and leveled flat. In images taken from the elbow of the lander’s stowed robotic arm, the edge of the crater is visible. Once the team determines the diameter of the crater—it could be meters, maybe tens of meters—researchers can infer its depth and the amount of sand blown into it. Either way, this bodes well for the heat probe instrument, called HP3, which should penetrate the material with ease. “This is about as good news for HP3 as you could possibly hope,” he says.

Landing in the hollow was fortunate for another reason. InSight didn’t quite hit the bull’s-eye of its target landing zone, and ended up in terrain that, overall, is rockier than desired. But the hollow is mostly devoid of rocks. One, about 20 centimeters across, sits close to the lander’s feet, whereas three smaller ones lie farther away—but none poses a threat to placing the instruments. The hollow is flat and lacks sand dunes, and small pebbles indicate a surface dense enough to support the weight of the instruments. “We won’t have any trouble whatsoever,” Golombek says.

They still need to pin down exactly where the lander is, on the surface. They know, within a few kilometers, but it will take more work to narrow that down to a precise location.


The lava tubes and canyons of Cerberus Fossae

Cerberus Fossae rock falls

Cool image time! In the November image release from the high resolution camera on Mars Reconnaissance Orbiter (MRO) I found the image on the right (cropped to post here), dubbed “Possible Rock Falls on Steep Slopes in Cerberus Fossae.” You can see the full image by clicking on the photo on the right.

The cropped section focuses on the steep cliffs of this deep canyon, formed when lava flowed down from the giant volcano Elysium Mons almost like water, following the faults created by the bulging volcanoes to carve a long series of parallel canyons more seven hundred miles in length. Not only can individual boulders be seen piled up on the base of the canyon, you can see on the lower right a large section of cliff that has broken off and partly fallen, propped now precariously on the cliff’s steep slope. I would not want to be hiking below it at the base of this canyon.

Elysium Mons and Cereberus Fossae

This photograph itself made me more interested in looking at other MRO images of Cerberus Fossae. The context map on the right shows that MRO has taken numerous images along the length of these faults, indicated by the red boxes. The location of the above image is shown by the white cross, at the western end where the canyons tend to be steep, deep, and pronounced. In taking a look at the many images of Cerberus Fossae, I found a variety of canyons, plus pit chains, lava tube skylights, and one especially intriguing image, posted below, that shows what appears to be an extended collapse along the length of what was once an underground lava tube.
» Read more


Scientists to pollute atmosphere to stop global warming

The coming dark age: In order to stop global warming a team of scientists plan a first test of a method designed to block sunlight by injecting aerosols (the scientific term for pollution) into the upper atmosphere.

If all goes as planned, the Harvard team will be the first in the world to move solar geoengineering out of the lab and into the stratosphere, with a project called the Stratospheric Controlled Perturbation Experiment (SCoPEx). The first phase — a US$3-million test involving two flights of a steerable balloon 20 kilometres above the southwest United States — could launch as early as the first half of 2019. Once in place, the experiment would release small plumes of calcium carbonate, each of around 100 grams, roughly equivalent to the amount found in an average bottle of off-the-shelf antacid. The balloon would then turn around to observe how the particles disperse.

The test itself is extremely modest. Dai, whose doctoral work over the past four years has involved building a tabletop device to simulate and measure chemical reactions in the stratosphere in advance of the experiment, does not stress about concerns over such research. “I’m studying a chemical substance,” she says. “It’s not like it’s a nuclear bomb.”

Nevertheless, the experiment will be the first to fly under the banner of solar geoengineering. And so it is under intense scrutiny, including from some environmental groups, who say such efforts are a dangerous distraction from addressing the only permanent solution to climate change: reducing greenhouse-gas emissions. The scientific outcome of SCoPEx doesn’t really matter, says Jim Thomas, co-executive director of the ETC Group, an environmental advocacy organization in Val-David, near Montreal, Canada, that opposes geoengineering: “This is as much an experiment in changing social norms and crossing a line as it is a science experiment.” [emphasis mine]

The number of stupid and ill-documented conclusions mentioned in this article are so many it would be hard to list them all. For one, it assumes the climate is warming in a disastrous manner, an assumption that remains entirely unproven. For another, the last paragraph in the quote above illustrates how much politics dominates this scientific field. Science has nothing to do with this experiment.

Third, the risks involved in doing this kind of geoengineering are impossible to measure. They very easily could be very negative, for us and the environment. Fourth, the only objections to this experiment quoted in the article come from activist groups who believe in global warming, but would rather impose political restrictions on freedom and property rights than do geoengineering. Skepticism of the global warming theory is merely mentioned as an aside, coming from “the occasional conspiracy theorist.”

I could go on. The worst part of this article and the scientists proposing this work is their utter refusal to consider the gigantic amounts of research that has shown the many benefits of increased atmospheric carbon dioxide and warming for agriculture and plant growth. Global warming, should it happen, could have negative consequences, but the data so far is very far from conclusive.

Let me add one more side note: The same environmentalists who generally support geoengineering to halt global warming are also likely to agree with this infantile op-ed: Richard Branson and Elon Musk threaten the purity of space.

Despite all the money the US and Russia have spent attempting to show who has the biggest balls, space remains pure. But, while Nasa re-engages and fuels up for another go, so-called space pioneers and entrepreneurs are already selling seats.

I don’t know about you, but I don’t want space to be commercialised, owner [sic] by Richard Branson or Elon Musk. For me, this would ruin something very special.

I’d suggest you read it all, but I would fear your level of education and ability to think will be seriously damaged.

For these anti-human environmentalists, manipulating the Earth’s atmosphere, based on weak scientific theories, is perfectly okay. Having humans and private enterprise in space, however, is evil and must be prevented at all costs.

The empty-headed lack of thought and ignorance required to come to these conclusions, simultaneously, boggles my mind.


InSight’s solar panels have opened

InSight engineers have now reported that solar panels have opened and are functioning properly.

NASA’s InSight has sent signals to Earth indicating that its solar panels are open and collecting sunlight on the Martian surface. NASA’s Mars Odyssey orbiter relayed the signals, which were received on Earth at about 5:30 p.m. PST (8:30 p.m. EST). Solar array deployment ensures the spacecraft can recharge its batteries each day. Odyssey also relayed a pair of images showing InSight’s landing site.

“The InSight team can rest a little easier tonight now that we know the spacecraft solar arrays are deployed and recharging the batteries,” said Tom Hoffman, InSight’s project manager at NASA’s Jet Propulsion Laboratory in Pasadena, California.

This was the last major event in the landing sequence, and with it they can now shift to the slow deployment of instruments over the next few weeks. Results from this spacecraft will not be sudden or spectacular. It is going to take time to get the spectrometer placed and than time to gather quake data.


Quasars that shut off

The uncertainty of science: Astronomers have discovered a class of quasars that suddenly turn off, something that no theory had predicted possible.

LaMassa, an astronomer now at the Space Telescope Science Institute, was mystified. Until that moment in 2014, she, like so many others, had expected quasars to be relatively stagnant. “Then you see these drastic changes within a human lifetime, and it’s pretty cool,” she said.

Confusion turned into excitement, and a hunt began to find more of these oddities. Although less luminous examples had already been seen, astronomers wanted to know if changes as dramatic as the one LaMassa discovered were common. It was no straightforward task, given that surveys tend not to go back and look at objects they have previously observed. But astronomers searched through archived data and discovered 50 to 100 more of what became known as “changing-look quasars.” Some of these have dimmed substantially more than LaMassa’s first example. Others have transitioned in the space of a month or two. And others, after disappearing, have reappeared again.

“It’s clear that the reason we weren’t finding these objects before is that we weren’t looking for them,” said Eric Morganson, an astronomer at the University of Illinois.

The article does a fine job of explaining the whole problem, including outlining the theories now being posited to explain these events. Bottom line: the universe is always more complicated that expected by initial observations.


Bennu from 85 miles

Bennu at 85 miles

The OSIRIS-REx science team today released a new image of Bennu, taken by the spacecraft from only 85 miles on November 16, two weeks ago Its contrast has been increased to bring out the details.

The asteroid continues to remind me of Ryugu, a rubble pile of boulders with few smooth spots. I suspect the OSIRIS-REx engineers are going to struggle as much as the Hayabusa-2 engineers are in an effort to find a safe spot to grab a sample. The advantage however for OSIRIS-REx is that the main body of the spacecraft doesn’t have to get as close to the surface as with Hayabusa-2. They will come down only close enough for the robot arm to touch down.

Rendezvous is set for December 3.


Present and future landing sites on Mars

With InSight’s landing on Mars set for 11:54 am (Pacific) this coming Monday, November 26, 2018, I decided to put together a map of Mars showing the location of all the successful landers/rovers, adding the landing sites for the planned landers/rovers through 2020. This will give some context to InSight’s landing site.

Landing sites on Mars

The map does not show the landing sites for the failed Soviet, American, and British landers.

As I noted in describing the Mars2020 landing site, the location of the bulk of these landing sites, along the transition zone from the southern highlands and the northern lowlands, demonstrates the areas of the planet that interest geologists the most. It is here that we find many shoreline features, suggestive of the ocean that many scientists theorize existed intermittently in the northern lowlands. It is here that planetary scientists can quickly gather the most information about Martian geological history. And it is here that they have the opportunity to study the widest range of rock types.

From an explorer’s perspective, however, this approach has its limits. It does not provide us a look at a wide variety of locations. It is not directly aimed at finding lower latitude locations where ice might actually exist. And it is decidedly not focused in studying the planet from the perspective of future colonists. I am sometimes frustrated that we have as yet no plans to send any rovers into Marineris Valles, or to the western slopes of Arsia Mons, the southern most volcano in the chain of three giant volcanoes where there are indications that ice might exist underground, or to any of the places where caves are known to exist where a colony could be built more easily. In fact, the caves on the slopes of Arsia Mons seems a prime exploration target.

Eventually these locations will be explored, likely by private landers aimed at scouting out locations for future private settlements. I am just impatient.


India wants international instruments for its Venus mission

The new colonial movement: India has requested science instruments proposals from the international community for its planned Venus orbiter, set to launch in 2023.

ISRO has already selected 12 instruments, proposed by Indian scientists, including cameras and chemical analyzers to study the atmosphere. Now, it’s hoping other scientists will join. “Planetary exploration should be all about global partnerships,” says Kailasavadivoo Sivan, a rocket scientist and ISRO’s chair. (The deadline for submitting proposals is 20 December.)

For me, the big news with this article is that it is the very first I have seen that actually spells out Sivan’s first name. Since he became head of ISRO in January 2018, he has only been listed as “K. Sivan” in every single article, even those describing his background when he was appointed. Now that I have learned what a tongue-twister that first name is, I can understand why they abbreviate it.

On a more serious note, this article indicates the growing maturity of India’s space effort. They not only are planning a mission to Venus, they will fly missions to the Moon in January and Mars in 2022, and intend to launch their first manned mission in that same time period.


Another star found that dims strangely like Tabby’s Star

Astronomers have found a second star that dims in an inexplicable manner, like Tabby’s Star.

Known as VVV-WIT-07, the star appears to be much older and redder than our sun, although the amount of interstellar dust between our solar system and the star’s home closer to the galactic center makes exact classification and distance measurements very difficult. What is certain is that in the summer of 2012, the object’s brightness faded slightly for 11 days, then plummeted over the following 48 days, suggesting that something blocked more than three quarters of the star’s light streaming toward Earth. But what could that “something” be?

According to Eric Mamajek, an astrophysicist at the University of Rochester unaffiliated with the VVV survey, such a profound degree of dimming suggests that a staggeringly large object or group of objects is blocking the light. “It’s got to be over a million kilometers wide, and very dense to be able to block that much starlight,” he says. Mamajek should know: He led the team that discovered J1407, another strange star periodically eclipsed by a planet-sized object thought to boast a massive ring system some 200 times broader than that of Saturn. In this latest case, he says, the strange signals from VVV-WIT-07 could arise from clumps or clouds of material passing between Earth and the star, though he cautioned that the data were preliminary and more observations are required.

Tabetha Boyajian agrees. Boyajian, an astronomer at Louisiana State University, was the lead author for the 2015 paper announcing the strange dimming of KIC 8462852, also known as Tabby’s Star, an unusual object first spotted by NASA’s Kepler Space Telescope. VVV-WIT-07 would have to harbor “a very peculiar kind of dust cloud to make these kinds of dips,” Boyajian says. Boyajian’s study helped spark a surge of public interest in Tabby’s Star because the star’s unusual dimming could be seen as evidence of an alien civilization building an artificial structure that soaked up the star’s light. More conventional explanations include a swarm of comets or fragments from a shattered planet, both of which would create significant clouds of dust and debris that could also occlude the star’s light. But, so far, no simple single explanation fits the complexities of the dimming seen around the star; researchers remain stymied in their attempts to understand the true nature of the strange dimming of Tabby’s Star.

As is usually the case in these cases, the explanation will not be aliens. That it could be, however, is what makes it so intriguing.


A young lunar impact crater

Lunar crater

Cool image time! The science team from Lunar Reconnaissance Orbiter (LRO) today released a new image, taken on November 3, 2018, of a relatively young small crater not easily seen from Earth.

The unnamed crater, just 1.8 kilometers across, is too small to see from Earth with unaided eyes. It is in the Moon’s wild west, just past Oceanus Procellarum and close to the line dividing the nearside from the farside, so it would be hard to glimpse in any case. If you stood on the crater rim, you would see the Earth forever slowly bobbing up, down, and sideways close to the eastern horizon.

The image above is a cropped and reduced-in-resolution section of the released image. If you click on it you can see this section at full resolution.

What I find fascinating about this crater are the black streaks that appear to only run down the outside slopes of the eastern rim, but nowhere else. At first glance it looks like prevailing winds, blowing from the west, caused this, but of course that’s wrong because the Moon has no atmosphere. The website explains:
» Read more


The soft landslides of Mars

A soft avalanche on Mars

Context image of landslide

The light gravity of Mars, combined with different materials, a lot of dust, and a geological history different from Earth, produces events that — though reminiscent of similar geological events on Earth — are definitely not the same.

The image above, cropped and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and was one of the many uncaptioned images released in the November archive. If you click on the image you can see the full resolution version. It shows the tongue of a landslide inside a crater located in the planet’s southern highlands.

You can immediately see why I call it a soft landslide. The craters on its top are barely visible, as if they hit a soft surface that absorbed most of the impact. The grooves spreading southward in the slide suggest that this solid material flowed almost like mud. And the soft, smooth surface head of the slide suggests an almost liquid-like flow. As far as I can tell, this landslide had few large boulders. It was made up instead of small particles of about the same size.

To the right is an image showing the wider context of the above image, taken by Mars Odyssey and cropped and annotated by me to post here. The white box shows the entire area photographed by the full resolution image of the landslide, with the tongue of the landslide at the bottom of the box. If you look at the floor of this crater, you can see what looks like the ghost of a past smaller impact, seemingly buried in either a field of lava or soft dusty regolith. The smoothness of the crater floor also suggests a material softness, allowing it to settle into a pondlike featureless flat plain.
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New Wolf-Rayet star discovered 8,000 light years away

Astronomers have discovered a Wolf-Rayet star — the kind of star thought to eventually cause major explosions — 8,000 light years away.

The binary star system, containing a pair of massive ‘Wolf-Rayet’ stars, has been discovered by an international team of researchers, including Professor Paul Crowther from the University of Sheffield, and published in Nature Astronomy.

Wolf-Rayet stars are amongst the hottest stars in the Universe, blast out powerful winds of hot gas, and represent the last stage in the evolution of the most massive stars prior to exploding as a supernova.

Located around 8,000 light years away – half a billion times further away than our Sun – the binary system is surrounded by a gigantic dust cloud. The collision between the winds of the two stars can form dust, which takes on elegant spiral pinwheel shapes as the stars orbit each other.

Expect to see a number of news articles hinting at how this system is a deadly threat to Earth. It is not. For one thing, it is too far away for any supernovae or gamma ray burst to cause serious harm here. Second, it will be a long time before any of that is going to happen.

Wolf-Rayet stars however are rare, and being able to study them helps astronomers better understand the life and death of stars. Having another so relatively close is a boon to astronomers.


Parker reports in

Scientists have received confirmation from the Parker Solar Probe that it successfully survived its first close fly-by of the Sun and that all its instruments were able to gather data.

All Parker Solar Probe systems are operating well and as designed. The solid state recorder on the spacecraft indicated that, as planned, the four instrument suites had recorded a significant amount of data, which is scheduled to be downloaded to Earth via the Deep Space Network over several weeks starting Dec. 7. In addition to helping scientists begin to explore fundamental questions about the physics of our star, the data from this initial perihelion — collected closer to the Sun than any before — will help instrument teams calibrate Parker Solar Probe’s instruments and plan future observations.

Parker will repeat this many times over the next seven years. And while it will provide us a ton of new knowledge about the Sun, it will also be proving out technology that future solar system travelers will use to get closer such hostile environments.


NASA picks Mars 2020 landing site: Jezero Crater

Jezero Crater

NASA has picked Jezero Crater has the landing site for its as yet unnamed 2020 Mars rover.

Jezero Crater is located on the western edge of Isidis Planitia, a giant impact basin just north of the Martian equator. Western Isidis presents some of the oldest and most scientifically interesting landscapes Mars has to offer. Mission scientists believe the 28-mile-wide (45-kilometer) crater, once home to an ancient river delta, could have collected and preserved ancient organic molecules and other potential signs of microbial life from the water and sediments that flowed into the crater billions of years ago.

Jezero Crater’s ancient lake-delta system offers many promising sampling targets of at least five different kinds of rock, including clays and carbonates that have high potential to preserve signatures of past life. In addition, the material carried into the delta from a large watershed may contain a wide variety of minerals from inside and outside the crater.

The geologic diversity that makes Jezero so appealing to Mars 2020 scientists also makes it a challenge for the team’s entry, descent and landing (EDL) engineers. Along with the massive nearby river delta and small crater impacts, the site contains numerous boulders and rocks to the east, cliffs to the west, and depressions filled with aeolian bedforms (wind-derived ripples in sand that could trap a rover) in several locations.

The red dot on the map of Mars below shows this location. The blue dot is Gale Crater where Curiosity landed. The purple dot is the landing site for the European ExoMars rover. The yellow dot is where Opportunity has been roving, and the black dot is Spirit’s location.
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Computer model suggests universe has innumerable exomoons

A supercomputer simulation has shown that ice-giant planets like Uranus and Neptune can have their own dust disk during formation, thus allowing these kinds of planets to also form moons.

“So far it was believed that Uranus and Neptune are too light to form such a disk,” says the astrophysicist. Therefore, it was considered that the moons of Uranus could have formed after a cosmic collision – like our own moon, also a relatively infrequent event as the capture. Now the researchers who are also members of the NCCR PlanetS were able to refute this previous idea. Their extremely complex computer simulations reveal that in fact Uranus and Neptune were making their own gas-dust disk while they were still forming. The calculations generated icy moons in-situ, that are very similar in composition with the current Uranian satellites. From the simulations performed by the supercomputer called “Mönch” at CSCS it is clear that Neptune originally also was orbited by a Uranus-like, multiple moon system, but this must have been wiped out during the capture of Triton.

The new study has a much wider impact on moons in general, than only on our Solar System formation history. “If ice giants can also form their own satellites, that means that the population of moons in the Universe is much more abundant than previously thought,” summarizes Dr.Szulágyi.Ice giants and mini-Neptune planets are often discovered by exoplanet surveys, so this planet mass category is very frequent. “We can therefore expect many more exomoon discoveries in the next decade,” the astrophysicist says.

I actually don’t believe the assumption posited here that scientists previously believed Uranus and Neptune were too light to form disks. I think many astronomers might have believed that, while many others remained unsure, since it is more intuitive to expect such disks to form as these gas giants formed.

Either way, this computer model lends weight to those who believe the universe is littered with planets and moons, everywhere, many of which will exist in the habitable zones of all kinds of stars. These planets and moons might not have life, but they will be places we could live, when we begin colonizing interstellar space.


Sunset/sunrise on Mars

The sun on Mars's horizon

Cool image time! The image on the right, reduced to post here, was taken by Curiosity during a photo campaign this week to monitor Mars’s atmosphere. It looks out to the horizon at the Sun. I think the view is eastward, at Mount Sharp, as the Sun rises, but I am not sure. It might be looking west across the crater rim at sunset.

If you click on the image you can see it at full resolution. The haziness in the atmosphere might be left over from this summer’s global dust storm, but probably not, as I have read numerous reports in connection with Opportunity saying the storm is completely over and the atmosphere has now cleared. More likely it is from the windy conditions that are simply present these days at Gale Crater.

Regardless, it is quite cool because it illustrates how far we have come since the first planetary missions half a century ago. We can now routinely watch a sunset on Mars.


Looking at the south pole of the Milky Way

Link here. The link provides instructions for finding the spot in the sky that corresponds to the south pole of the galaxy, pointing in a perpendicular direction away from its center.

No star marks the position. It sits in the faint southern constellation of Sculptor, the sculptor’s studio, hence its identification is intellectual rather than sensorial.

This is the case of the dog that did not bark. The reason there is little to see there is that you will be looking down out of the plane of the galaxy, in a direction with the fewest stars to see. The view is therefore looking out of our galaxy, at intergalactic space, vast and empty.


OSIRIS-REx unfolds its robot arm

In preparation for its December 3 rendezvous with the asteroid Bennu OSIRIS-REx successfully unfolded its robot arm for the first time since launch this week.

The website has a nice short video showing how the arm will grab its samples. Very innovative, and not what you would expect. The technique had to be clever because Bennu is so small and has such a tiny gravity.

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