Tag: science

Hubble finds galaxy with no evidence of dark matter

12:29 pm

The uncertainty of science: Using the Hubble Space Telescope astronomers have discovered a nearby galaxy that apparently has little or no evidence of dark matter.

The unique galaxy, called NGC 1052-DF2, contains at most 1/400th the amount of dark matter that astronomers had expected. The galaxy is as large as our Milky Way, but it had escaped attention because it contains only 1/200th the number of stars. Given the object’s large size and faint appearance, astronomers classify NGC 1052-DF2 as an ultra-diffuse galaxy. A 2015 survey of the Coma galaxy cluster showed these large, faint objects to be surprisingly common.

But none of the ultra-diffuse galaxies discovered so far have been found to be lacking in dark matter. So even among this unusual class of galaxy, NGC 1052-DF2 is an oddball.

Van Dokkum and his team spotted the galaxy with the Dragonfly Telephoto Array, a custom-built telescope in New Mexico they designed to find these ghostly galaxies. They then used the W.M. Keck Observatory in Hawaii to measure the motions of 10 giant groupings of stars called globular clusters in the galaxy. Keck revealed that the globular clusters were moving at relatively low speeds, less than 23,000 miles per hour. Stars and clusters in the outskirts of galaxies containing dark matter move at least three times faster. From those measurements, the team calculated the galaxy’s mass. “If there is any dark matter at all, it’s very little,” van Dokkum explained. “The stars in the galaxy can account for all the mass, and there doesn’t seem to be any room for dark matter.”

The galaxy is unusual in many other ways.

The Hubble images also revealed the galaxy’s unusual appearance. “I spent an hour just staring at the Hubble image,” van Dokkum recalled. “It’s so rare, particularly these days after so many years of Hubble, that you get an image of something and you say, ‘I’ve never seen that before.’ This thing is astonishing: a gigantic blob that you can look through. It’s so sparse that you see all of the galaxies behind it. It is literally a see-through galaxy.”

The ghostly galaxy doesn’t have a noticeable central region, or even spiral arms and a disk, typical features of a spiral galaxy. But it doesn’t look like an elliptical galaxy, either. The galaxy also shows no evidence that it houses a central black hole. Based on the colors of its globular clusters, the galaxy is about 10 billion years old. Even the globular clusters are oddballs: they are twice as large as typical stellar groupings seen in other galaxies.

The bottom line here is that we have only circumstantial evidence that dark matter exists, based solely on the fact that in all other measured galaxies, the outer stars rotate much faster than they should. That rotation speed however does not guarantee the existence of dark matter, only that something is causing the fast rotation. And the lack thereof in this galaxy puts a big crimp in the theory that dark matter exists, since the theories that posit its existence almost require it to be present in every galaxy.

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The James Webb Telescope: a signpost for identifying fake news sources

11:35 am

The news yesterday that NASA will once again have to delay the launch of the James Webb Space Telescope due to a variety of technical issues and management errors not only exemplified the fundamental failure of the federal government, it also illustrated the routine failures of today’s mainstream press.

First, Webb’s new delay epitomizes the systemic incompetence of Washington. Despite being 13 years behind schedule and costing eight times more than originally planned, NASA and its contractors still couldn’t get things right.

Most of the problems have occurred with the spacecraft half of the project, which was built by Northrop Grumman in California and is undergoing testing there. During the teleconference, NASA officials, including acting Administrator Robert Lightfoot, expanded upon technical problems first reported publicly by the agency’s inspector general last month.

These include leaky valves within the spacecraft’s propulsion system and difficulties encountered during deployment tests of the sun shield. Not only did the thin, five-layer sun shield snag during the deployment, but technicians also found seven tears up to 10cm long within the material. NASA and Northrop Grumman have identified fixes for these problems, but their repair has added months of delays to the project, and engineers cannot be sure that more issues will not crop up during further testing.

Such failures, in NASA and in all big federal projects in recent years, are hardly news. Only the willfully blind or those who support wasting tax dollars to distribute pork will deny they exist.

The failures of the federal government however is not the focus of this essay. Instead, the announcement yesterday and the coverage of it by the press provides us a perfect and very obvious signpost for differentiating between the fake news sources that are generally unreliable or too often allow their biases to influence their reporting, and those sources that do a good job.

That signpost is one simple fact: Webb is not a replacement or successor to the Hubble Space Telescope, despite NASA making this false claim for decades. Hubble is an optical telescope. Webb will view the universe in the infrared. These are too entirely different things.

Yet, too many news sources today repeated NASA’s false claim, illustrating how little they know about both telescopes and their design, while revealing their complete inability to do some basic journalistic research. Instead they merely rewrite old press releases, and thus prove clearly by their bad reporting why so many people have so little respect for the modern press.

The worst examples made this false claim right in the headline:
» Read more

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Webb telescope delayed again to 2020

10:34 am

NASA has announced that it is once again delaying the launch of the James Webb Space Telescope, from 2019 to 2020.

The observatory was supposed to fly this year. But last fall, NASA bumped the launch to 2019. NASA announced the latest delay on Tuesday. “We have one shot to get this right before going into space,” said Thomas Zurbuchen, NASA’s associate administrator of science. He said some mistakes were made while preparing the telescope, and NASA underestimated the scale of the job. [emphasis mine]

None of this is a surprise. Webb is more pork than science. It was originally budgeted at $1 billion, with a planned launch in 2011. It will now cost more than $9 billion, and be delayed almost a decade. Since the project began in the early 2000s, by the time it launches it will have been in development for almost two decades, which is almost a lifetime career for some people.

And note, the article includes the lie that Webb is “a successor to the Hubble Space Telescope.” It is not. Hubble is an optical telescope. Webb will only look in the infrared. These are very different things.

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Tabby’s Star dims again

8:37 am

Scientists studying Tabby’s Star have revealed that it suddenly dimmed last week, the most since 2013, and then just as quickly returned almost to normal.

The latest dimming event started with a slow decline and ended with a rapid increase in brightness, Boyajian and her team wrote on their blog. Dust from a backward comet tail and then larger chunks from the broken-up body would explain that uneven pattern.

At this time the evidence clearly points not to alien megastructures but to clouds of fine dust whose structure and origin remain puzzling.

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India delays Chandrayaan-2 six months

5:46 pm

Because engineers wished more time, India has delayed the launch of its second unmanned Moon mission, Chandrayaan-2, from April to October.

Union Minister of State in the Prime Minister’s Office, in-charge of the Department of Space, Jitendra Singh had on 16 February last said the lunar mission under which the Isro will for the first time attempt to land a rover on the moon’s south pole, will be launched in April.

Sivan (head of ISRO) had earlier said the window to launch the Rs800 crore mission was between April and November 2018. While the “targeted date” was April, Isro would launch the mission in October or November, he had said.

This is a very ambitious mission, so pushing the launch back to October seems quite reasonable. That they are aiming for the south pole is also smart, especially since NASA has abandoned that location as a target to instead build a giant Potemkin village orbiting the Moon, where it can accomplish nothing.

Posted between Flagstaff and Phoenix as we head back from a very successful four-day caving expedition in the Grand Canyon.

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Mars rover update: March 21, 2018

2:10 pm

Summary: Curiosity continues its exploration of Vera Rubin Ridge, including several drilling attempts. Opportunity is halfway down Perseverance Valley.

For a complete list of all past updates going back to July 2016, see my February 8, 2018 update.

Curiosity

Curiosity's traverse map, Sol 1993

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

Since my February 8, 2018 update, the Curiosity science team has apparently been loath to leave Vera Rubin Ridge. They had begun the trek to the northeast that would take them towards the exit ridge heading to the southeast, as indicated by the dotted red line on the traverse map above, but then continued past that planned route to continue to the northeast. Along the way they attempted to drill twice using an improvised approach that they hoped would bypass the drill’s stuck feed mechanism, without apparent success.

The panorama below is looking to the west and south, as indicated by the yellow lines in the image above.
» Read more

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Star’s close approach 70,000 years ago pinned to cometary orbits

10:03 am

Astronomers now think they have pinned the orbits of about 340 comets to another star’s close approach to our solar system 70,000 years ago.

About 70,000 years ago, when the human species was already on Earth, a small reddish star approached our solar system and gravitationally disturbed comets and asteroids. Astronomers from the Complutense University of Madrid and the University of Cambridge have verified that the movement of some of these objects is still marked by that stellar encounter. At a time when modern humans were beginning to leave Africa and the Neanderthals were living on our planet, Scholz’s star – named after the German astronomer who discovered it – approached less than a light-year from the Sun. Nowadays it is almost 20 light-years away, but 70,000 years ago it entered the Oort cloud, a reservoir of trans-Neptunian objects located at the confines of the solar system.

This discovery was made public in 2015 by a team of astronomers led by Professor Eric Mamajek of the University of Rochester (USA). The details of that stellar flyby, the closest documented so far, were presented in The Astrophysical Journal Letters.

Now two astronomers from the Complutense University of Madrid, the brothers Carlos and Raúl de la Fuente Marcos, together with the researcher Sverre J. Aarseth of the University of Cambridge (United Kingdom), have analyzed for the first time the nearly 340 objects of the solar system with hyperbolic orbits (very open V-shaped, not the typical elliptical), and in doing so they have detected that the trajectory of some of them is influenced by the passage of Scholz´s star.

It is likely that the close approach influenced a lot more objects, many of which might not have yet arrived in the inner solar system. Moreover, their computer models suggest that the star might have come closer to the Sun than 0.6 light years.

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New theory suggests Mars’ oceans formed earlier and intermittently

11:19 am

Scientists have proposed a new model for the existence of oceans on Mars’ northern plains that proposes they formed earlier, were shallower, were variable in size, and formed in conjunction with the eruptions that formed the planet’s giant volcanoes.

The proposal by UC Berkeley geophysicists links the existence of oceans early in Mars history to the rise of the solar system’s largest volcanic system, Tharsis, and highlights the key role played by global warming in allowing liquid water to exist on Mars. “Volcanoes may be important in creating the conditions for Mars to be wet,” said Michael Manga, a UC Berkeley professor of earth and planetary science and senior author of a paper appearing in Nature this week and posted online March 19.

…The new model proposes that the oceans formed before or at the same time as Mars’ largest volcanic feature, Tharsis, instead of after Tharsis formed 3.7 billion years ago. Because Tharsis was smaller at that time, it did not distort the planet as much as it did later, in particular the plains that cover most of the northern hemisphere and are the presumed ancient seabed. The absence of crustal deformation from Tharsis means the seas would have been shallower, holding about half the water of earlier estimates. “The assumption was that Tharsis formed quickly and early, rather than gradually, and that the oceans came later,” Manga said. “We’re saying that the oceans predate and accompany the lava outpourings that made Tharsis.”

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Scientists theorize that Oumuamua came from a binary star system

8:17 am

Based on statistics and computer modeling, some scientists believe that the interstellar object Oumuamau likely came from stellar binary system.

For the new study, published in the journal Monthly Notices of the Royal Astronomical Society, Jackson and his co-authors set about testing how efficient binary star systems are at ejecting objects. They also looked at how common these star systems are in the Galaxy. They found that rocky objects like ‘Oumuamua are far more likely to come from binary than single star systems. They were also able to determine that rocky objects are ejected from binary systems in comparable numbers to icy objects.

Their conclusion does make sense, though any good scientist would retain a gigantic sense of skepticism. While it is statistically reasonable to conclude that a majority of interstellar objects should come from binary systems, there is no guarantee that Oumuamua in particular did so. Even if the odds were one in a million, there is always that one, and the universe often seems prone to fooling us.

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North American mountains get 3Xs the snow previously estimated

8:30 am

The uncertainty of science: A new analysis based on computer models suggests that the mountains of North America get three times more snow each year than scientists has previously estimated.

Those figures come thanks to a new analysis in which researchers used computer simulations to estimate the typical annual snowfall in each of 11 North American mountain ranges. After supercomputer simulations of regional climate that would have taken 50 years on the average laptop, the team found that those mountain ranges receive about 3018 cubic kilometers of snow a year. Although those ranges together cover only about 25% of the area stretching from the Arctic Ocean down to Mexico’s southern border, they get about 60% of its snow, the researchers report in Geophysical Research Letters. That’s nearly three times the estimate for mountain snow from one previous study, the team notes.

First, this is based on computer simulations, not actual data in the field. I wouldn’t put much money on it. Second, it does show us how little climate scientists really know about the climate, as this simulation is still using all the knowledge they have, and it comes up with a conclusion that confounds them. Third, I was astonished the article didn’t try to push the idea that this larger estimate should be blamed on human-caused global warming. It didn’t, which I suppose is a sign of some progress.

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Dawn finds recent changes on Ceres

4:28 pm

New data from Dawn has found at least one spot on Ceres where recent changes appear to have occurred on the surface.

Observations obtained by the visible and infrared mapping spectrometer (VIR) on the Dawn spacecraft previously found water ice in a dozen sites on Ceres. The new study revealed the abundance of ice on the northern wall of Juling Crater, a crater 12 miles (20 kilometers) in diameter. The new observations, conducted from April through October 2016, show an increase in the amount of ice on the crater wall. “This is the first direct detection of change on the surface of Ceres,” said Andrea Raponi of the Institute of Astrophysics and Planetary Science in Rome.

Raponi led the new study, which found changes in the amount of ice exposed on the dwarf planet. “The combination of Ceres moving closer to the sun in its orbit, along with seasonal change, triggers the release of water vapor from the subsurface, which then condenses on the cold crater wall. This causes an increase in the amount of exposed ice. The warming might also cause landslides on the crater walls that expose fresh ice patches.”

There is a certain irony here. For eons, the only alien body that humans were able to get a good look at, the Moon, was also an object where almost nothing changed. Even today, after humans have visited its surface and numerous orbiting spacecraft have photographed its surface in numbing detail, the Moon has generally been found to be stable and unchanging. Though impacts do occur, and the surface does evolve over time, the Moon is probably one of the most static bodies in the solar system.

The irony is that this lunar stability gave us an incorrect impression of the rest of the solar system. Based on the Moon, it was assumed that airless or almost airless bodies like Mercury, Mars, Pluto, the large moons of Jupiter and Saturn, and asteroids like Ceres would also be stable and unchanging. What we have instead found is that the Moon is the exception that proves the rule. Most of these other worlds are unlike the Moon. They show a lot of surface evolution, over relatively short time scales. They change.

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Kepler to run out of fuel in the coming months

1:08 pm

After nine years of success, the Kepler space telescope is running out of fuel, which will force an end to the mission sometime in the next several months.

The Kepler team is planning to collect as much science data as possible in its remaining time and beam it back to Earth before the loss of the fuel-powered thrusters means that we can’t aim the spacecraft for data transfer. We even have plans to take some final calibration data with the last bit of fuel, if the opportunity presents itself.

Without a gas gauge, we have been monitoring the spacecraft for warning signs of low fuel— such as a drop in the fuel tank’s pressure and changes in the performance of the thrusters. But in the end, we only have an estimate – not precise knowledge. Taking these measurements helps us decide how long we can comfortably keep collecting scientific data.

They are doing a dance here. If they run out of fuel while collecting data, that data will be lost. If they stop collecting data too soon, however, to transmit it to Earth, they will not maximize the data obtained.

Meanwhile, the next exoplanet hunter, TESS, is scheduled for launch on April 16 on a Falcon 9 rocket.

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Chandra looks back at the Crab Nebula

8:22 am

Link here. It is almost twenty years since the Chandra X-Ray Observatory was launched, and in celebration the science team have released another X-ray image of the Crab Nebula, taken in 2017 in league with an optical image from the Hubble Space Telescope and an infrared image from the Spitzer Space Telescope. They have also provided links to all similar past images, going back to 1999.

Some of the images are actually videos, in 2002 and 2011, showing the Crab’s dynamic nature. You can actually see flares and waves of radiation rippling out from its center.

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New Horizons team picks Ultima Thule as nickname for 2014 MU69

5:27 pm

In their continuing effort to give interesting names to their targets, the New Horizons team has chosen the name Ultima Thule for 2014 MU69, the Kuiper Belt object it will fly past on January 1, 2019.

With substantial public input, the team has chosen “Ultima Thule” (pronounced ultima thoo-lee”) for the Kuiper Belt object the New Horizons spacecraft will explore on Jan. 1, 2019. Officially known as 2014 MU69, the object, which orbits a billion miles beyond Pluto, will be the most primitive world ever observed by spacecraft – in the farthest planetary encounter in history.

Thule was a mythical, far-northern island in medieval literature and cartography. Ultima Thule means “beyond Thule”– beyond the borders of the known world—symbolizing the exploration of the distant Kuiper Belt and Kuiper Belt objects that New Horizons is performing, something never before done.

“MU69 is humanity’s next Ultima Thule,” said Alan Stern, New Horizons principal investigator from Southwest Research Institute in Boulder, Colorado. “Our spacecraft is heading beyond the limits of the known worlds, to what will be this mission’s next achievement. Since this will be the farthest exploration of any object in space in history, I like to call our flyby target Ultima, for short, symbolizing this ultimate exploration by NASA and our team.”

Their spacecraft will be the first to see this object up close. It is their right to name it. And if the International Astronomical Union objects, they can go to hell. I guarantee that future generations of space-farers will know this tiny world by this name, and this name alone.

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An even more spectacular movie of Jupiter’s storms

8:45 am

Cool image time! Yesterday I posted a short gif created by citizen scientist Gerald Eichstädt, using twelve Juno images, that showed some cloud changes over time. Today, I discovered that Eichstädt has created an even more spectacular movie, which I have embedded below the fold, based on images taken during Juno’s tenth close fly-by.

This movie shows the short-term dynamics Jupiter’s southern storms derived from raw JunoCam images of Juno’s Perijove-10 flyby on Dec 16, 2017.

You might also notice the effect of changing solar illumination on the appearance of the haze bands. JunoCam usually takes a time-lapse sequence of images during each perijove showing Jupiter’s polar regions. These images are taken from different perspectives along Juno’s trajectory. But it’s possible to reproject the JunoCam images to a common perspective. Displaying such a sequence rapidly reveals cloud motion in Jupiter’s storm systems.

This movie applies this technique. At the same time, it is changing the simulated perspective along Juno’s trajectory. The same short sequence of images is displayed in a loop, but due to the changing way of reprojecting the raw images, the shown surface area is changing more or less continuously.

Eichstädt warns that the blinking nature of the film might make it unsuitable for those with epilepsy. If this is not an issue for you, you should then definitely take a look.
» Read more

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A Juno movie of cloud motions

9:12 am

Cool image time! Citizen scientist Gerald Eichstädt, using twelve Juno images, has compiled a short gif movie that shows a tiny amount of cloud movement.

I think this is one of the first times Juno has show us even a tiny bit of cloud evolution, information that is essential for gaining a true understanding of Jupiter’s slightly less than 2000 mile deep atmosphere. To see it, go to the link. As Eichstadt notes, “Individual images are noisy, but we see cloud motion.”

When you watch, zoom in on the upper right quarter. This is the area that the cloud motion is seen best.

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Martian craters go splat!

2:17 pm

Overview of the volcanic Tharsis Bulge on Mars

Cool image time! In continuing my exploration of this month’s Mars Reconnaissance Orbiter (MRO) image release, I found two interesting images of small craters, one as part of that image release, the other found completely by accident.

The map on the right, taken from the MRO HiRISE archive page, shows the locations of these two images. Both are located in the lava plains that surround the giant volcano Pavonis Mons, the central volcano of the three volcanoes to the east of Olympus Mons. Previously, I have done posts focusing specifically on both Pavonis Mons and Arsia Mons. Not only is the geology of these gigantic volcanoes fascinating, there is evidence that ancient glacial ice lurks in lava tubes on their slopes, making them potentially prime real estate for future explorers.

The first image, labeled #1 on the image above, was taken in January 2018 to get a better look at a small crater on the surrounding lava plains, and was part of the MRO March image release. I have cropped it to post here, focusing on the crater itself.

My first reaction on seeing the image was, “Did this impact not go splat when it hit?”
» Read more

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Jupiter has a 1,900 mile deep atmosphere

5:13 pm

The uncertainty of science: New results from Juno reveal that the jet-stream-type bands visible on the surface extend down to 1,900 miles, deeper than expected. Below that,

…the planet rotates nearly as a rigid body.”This is really an amazing result, and future measurements by Juno will help us understand how the transition works between the weather layer and the rigid body below,” said Tristan Guillot, a Juno co-investigator from the Université Côte d’Azur, Nice, France, and lead author of the paper on Jupiter’s deep interior. “Juno’s discovery has implications for other worlds in our solar system and beyond. Our results imply that the outer differentially-rotating region should be at least three times deeper in Saturn and shallower in massive giant planets and brown dwarf stars.”

Scientists had not expected the atmosphere go that deep.

Other results show that that the gas giant’s complex polar regions are surprising as well.

Its north pole is dominated by a central cyclone surrounded by eight circumpolar cyclones with diameters ranging from 2,500 to 2,900 miles (4,000 to 4,600 kilometers) across. Jupiter’s south pole also contains a central cyclone, but it is surrounded by five cyclones with diameters ranging from 3,500 to 4,300 miles (5,600 to 7,000 kilometers) in diameter. Almost all the polar cyclones, at both poles, are so densely packed that their spiral arms come in contact with adjacent cyclones. However, as tightly spaced as the cyclones are, they have remained distinct, with individual morphologies over the seven months of observations detailed in the paper.

“The question is, why do they not merge?” said Adriani. “We know with Cassini data that Saturn has a single cyclonic vortex at each pole. We are beginning to realize that not all gas giants are created equal.”

I am always baffled when scientists are surprised at the infinite variety of the universe. It is absurd to assume Jupiter and Saturn would be alike, especially considering the history of solar system exploration since the dawn of the space age. Since the first probe got a close look at the Moon, every single new object observed has been completely different from every other previously observed object. Every object has been unique. None have been the same.

Jupiter should be no different. And I guarantee that the next fifty gas giants we finally get a close look at out there among the stars will be as different from each other as they are from Jupiter. It is going to take a lot of exploration for us to finally get a handle on the overall patterns of planetary formation.

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ESA successfully tests an air-breathing ion thruster

8:01 am

Engineers from the European Space Agency (ESA) and an Italian company have successfully tested a prototype of an ion engine that would obtain its fuel from the thin atmosphere available in low Earth orbit, thus allowing it to operate practically indefinitely.

From the press release:

Replacing onboard propellant with atmospheric molecules would create a new class of satellites able to operate in very low orbits for long periods. Air-breathing electric thrusters could also be used at the outer fringes of atmospheres of other planets, drawing on the carbon dioxide of Mars, for instance. “This project began with a novel design to scoop up air molecules as propellant from the top of Earth’s atmosphere at around 200 km altitude with a typical speed of 7.8 km/s,” explains ESA’s Louis Walpot.

Think about it. You supply your planetary probe one or more of these engines, and once it reaches orbit around its target it has an unlimited fuel supply to do research just about forever. More important, such technology when further refined is going to enhance human exploration as well. For example, rather than use the atmosphere at it arrives, later designs could simply dive into the atmosphere to get the spaceship’s tank refilled. Such engines would make spacecraft free from the tether of Earth.

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Sunspot update for February 2018

12:25 pm

It’s time for my monthly sunspot update. On Sunday NOAA posted its monthly update of the solar cycle, covering sunspot activity for February 2018. Below the fold is my annotated version of that graph.

Sunspot activity in February continued the low activity seen in November, December, and January, with November 2017 still the most inactive month for sunspots since the middle of 2009. In fact, the low activity we are seeing now is somewhat comparable to the low activity seen during the ramp down to solar minimum in the first half of 2008. By the end of that year we had hit solar minimum, the deepest and longest in a hundred years, suggesting that we might even hit solar minimum before the end of this year. That would have this happen at least a year earlier than all predictions.
» Read more

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More weird Mars geology

8:55 am

Low resolution of full image of crater

Cool image time! Yesterday the Mars Reconnaissance Orbiter team released 460 images taken by the spacecraft’s high resolution camera, HiRISE, as part of their normal and routine image release program. Obsessed with space exploration as I am, I like to scan through these new images to see if there is anything interesting hidden there that will show up eventually in a press release. For example, the first image in this release is a look at Vera Rubin Ridge and Curiosity. I would not be surprised if there is a press release soon using this image, probably aimed at outlining the rover’s future route up Mount Sharp. (The present overview traverse map is getting out of date.)

Sometimes however I find images that might never get a press release but probably deserve it. The image on the right, reduced in resolution to show here, is one such example. It is a strip taken from rim to rim across an unnamed crater located in the mid-northern latitudes of Mars, west of Olympus Mons. A review of past images by other Mars orbiters/probes suggests that no good high resolution image of this crater had ever been taken before.

If you click on the image on the right, or go to the actual image site, you can see the original in full resolution. It is definitely worthwhile doing this, because the strip shows some strange and inexplicable geology on the floor of the crater as well in its confusing central peak region. Numerous features appear to have been exposed by later erosion. The many small craters for example are I think what planetary geologists call pedestal craters. The surrounding terrain is less erosion-resistant, so as that terrain erodes away it leaves the crater behind, with its floor actually sitting higher than the surrounding flats.

What makes these craters even weirder however is that their rims appear to have eroded away even more than the surrounding terrain, so that all of these small craters (assuming that is what they are) have ringlike depressions surrounding a circular platform.

In the crater’s central peak region the terrain is even more strange. Sticking up out of the ground are some arched short ridgelines, which appear to have been exposed by erosion. That peak area however also has many strange flow features that I find completely baffling. It almost appears to me that as the molten peak area started to solidify after impact, someone went in with a stirring spoon and did some mixing!

The map below the fold provides the location context for this crater, with the crater’s location indicated by the arrow.
» Read more

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Methane detected on Enceladus could come from microbes

8:38 am

The uncertainty of science: New research has found that the methane that Cassini detected being released from Enceladus’s interior could conceivably come from at least one Earth-type microbe.

Using various mixtures of gases held at a range of temperatures and pressures in enclosed chambers called “bioreactors,” Rittmann and his co-authors cultivated three microorganisms belonging to the oldest branch of Earth’s tree of life, known as Archaea. In particular, they focused on Archaean microbes that are also methanogens, which are able to live without oxygen and produce methane from that anaerobic metabolism. The team examined the simplest types of microbes, which could be the primary producers of methane at the base of a possibly more complex ecological food chain within the moon.

They tried to simulate the conditions that could exist within and around Enceladus’s hydrothermal vents, which are thought to resemble those found at a few deep-sea sites on Earth, often near volcanically active mid-oceanic ridges. According to their tests, only one candidate, the deep-sea microbe Methanothermococcus okinawensis, could grow there—even in the presence of compounds such as ammonia and carbon monoxide, which hinder the growth of other similar organisms.

There are a lot of fake news stories today trumpeting this result as proof that alien microbes can exist on Enceladus. The data does no such thing. All it shows that one methane producing microbe could possibly live in an environment that researchers guess might somewhat resemble the situation on Enceladus. However, as the article admits,

Scientists do not really know the precise conditions on Enceladus yet, of course. And in any case it is possible any life there, if it exists, is nothing like any DNA-based organism on our planet, rendering our Earth-based extrapolations moot. What’s more, these findings only show microbial life might exist in one particular subset of possible environments within the moon’s dark ocean.

This result is interesting, but it really proves nothing about Enceladus itself.

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New backers to run Arecibo

8:27 am

The National Science Foundation this week revealed the make-up of the consortium that is taking over the operation of the Arecibo radio telescope in Puerto Rico.

The new agreement is valued at $20.15 million over five years, subject to the availability of funds, and is scheduled to begin April 1, according to the statement.

The new partnership represents a mixture of academic and corporate interests. The Universidad Metropolitana in San Juan, Puerto Rico, and Yang Enterprises Inc. in Oviedo, Florida, will partner with [the University of Central Florida] to manage the observatory. The team plans to expand the capabilities of the telescope, officials said.

This relieves the National Science Foundation (and the taxpayers) of the the cost burden for this facility, at least directly.

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Hubble finds new figure for universe expansion rate

6:58 am

The uncertainty of science: Using data from the Hubble Space Telescope astronomers have found evidence that universe’s expansion rate is faster than estimated in previous measurements.

The new findings show that eight Cepheid variables in our Milky Way galaxy are up to 10 times farther away than any previously analyzed star of this kind. Those Cepheids are more challenging to measure than others because they reside between 6,000 and 12,000 light-years from Earth. To handle that distance, the researchers developed a new scanning technique that allowed the Hubble Space Telescope to periodically measure a star’s position at a rate of 1,000 times per minute, thus increasing the accuracy of the stars’ true brightness and distance, according to the statement.

The researchers compared their findings to earlier data from the European Space Agency’s (ESA) Planck satellite. During its four-year mission, the Planck satellite mapped leftover radiation from the Big Bang, also known as the cosmic microwave background. The Planck data revealed a Hubble constant between 67 and 69 kilometers per second per megaparsec. (A megaparsec is roughly 3 million light-years.)

However, the Planck data gives a constant about 9 percent lower than that of the new Hubble measurements, which estimate that the universe is expanding at 73 kilometers per second per megaparsec, therefore suggesting that galaxies are moving faster than expected, according to the statement.

“Both results have been tested multiple ways, so barring a series of unrelated mistakes, it is increasingly likely that this is not a bug but a feature of the universe,” Riess said. [emphasis mine]

I should point out that one of the first big results from Hubble in 1995 (which also happened to be the subject one of my early published stories), the estimate then for the Hubble constant was 80 kilometers per second per megaparsec. At the time, the astronomers who did the research were very certain they had it right. Others have theorized that the number could be as low as 30 kilometers per second per megaparsec.

What is important about this number is that it determines how long ago the Big Bang is thought to have occurred. Lower numbers mean it took place farther in the past. Higher numbers mean the universe is very young.

That scientists keep getting different results only suggests to me that they simply do not yet have enough data to lock the number down firmly.

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Microbes found that survive in the driest desert on Earth

6:18 am

Scientists have found that certain microbes can remain dormant for years in the Atacama Desert and then come to life during the rare times water is available.

The Atacama Desert stretches inland 1000 kilometers from the Pacific coast of Chile, and rainfall can be as low as 8 millimeters per year. There’s so little precipitation that there’s very little weathering, so over time the surface has built up a crusty layer of salts, further discouraging life there. “You can drive for 100 kilometers and not see anything like a blade of grass,” Neilson says. Although she and others have found some bacteria there, many biologists have argued that those microbes are not full-time residents, but were blown in, where they die a slow death.

But that didn’t deter Dirk Schulze-Makuch, an astrobiologist at the Technical University of Berlin. “I like to go to places where people say nothing is alive,” he says. “We decided to take a shotgun approach and throw all the new [analytical] approaches at everything—fungi, bacteria, viruses”—that might be there. He and his team collected samples from eight places in the Atacama—from the coast eastward to the driest places—over 3 years. They first gathered material a month after a record-setting rain in 2015, and then followed up with yearly collections in some of the same places in 2016 and 2017. They sequenced all the copies of a gene known to distinguish microbial species to determine what was in those samples and even recovered some full genomes. The researchers also did a test to determine the proportion of DNA that came from intact, living cells. Finally, they assessed the amount of cellular activity; of adenosine triphosphate (ATP), a molecule the fuels this activity; and of byproducts—including fatty acids and protein building blocks—that resulted from that activity to look for additional evidence of life.

The coastal samples contained the most number and diversity of microbes, but in 2015, there were signs of life even in the driest spots, Schulze-Makuch and his colleagues report today in the Proceedings of the National Academy of Sciences. “Following a rainfall event, there is a flush of activity and [cells] are replicating,” Neilson says.

The researchers, as well as the article, push the idea that this result makes life on Mars more possible, but I think that is pushing things quite a bit. The Earth is so filled with life that to find a spot that doesn’t have life on it is almost impossible. The odds work in the favor of hardy life in difficult places. Mars however appears generally lifeless, which makes the odds of there being life more unlikely. Moreover, while the Atacama has many similarities to Mars, the differences are quite profound. To extrapolate any possibilities to Mars from this research is a big overstatement.

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Identifying the mysterious dark bands in Venus’s atmosphere

12:10 am

The uncertainty of science: Scientists have now proposed two new best candidates for the unknown major component in Venus’s upper atmosphere that was first identified in 1974 when Mariner 10 took the first good close-up images.

We have analyzed spectra taken during the second Venus flyby of MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft on its route to Mercury, in 2007. Using a numerical code, we have reproduced the light reflected by the equatorial atmosphere of the planet and retrieved the distribution of particles in the upper atmosphere of Venus, with a cloud top of some 75 km above the surface. We have also retrieved the absorption spectrum of the puzzling absorber and compared it with some previously proposed candidates. While no perfect match is found, sulfur-bearing species (S2O and S2O2) provide the best agreement. There is still a long way to undoubtedly identify Venus’s UV absorber, but this work provides substantial spectral constraints.

The dark absorber shows up as dark streaks in the upper atmosphere, and allows images to track wind and cloud movement. No one has been able to firmly identify it.

S2O and S2O2 are disulfur monoxide and disulfur dioxide respectively, both of which are unstable on Earth. The first is thought to have been detected in Io’s numerous volcanic eruptions, with it settling as a solid around at least one volcano, Pele. The second has already been suggested as the dark absorber. This research helps confirm that earlier research.

Note however that other research says there is too little sulfur in Venus’s atmosphere for this to be its dark absorber. The science here therefore remains decidedly unsettled.

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Mars Reconnaissance Orbiter in safe mode

8:26 am

After detecting low battery voltage, Mars Reconnaissance Orbiter (MRO) went into safe mode on February 15.

The orbiter is solar-powered but relies on a pair of nickel-hydrogen batteries during periods when it is in the shadow of Mars for a portion of each orbit. The two are used together, maintaining almost identical charge during normal operations.

The spacecraft remains in communication with Earth and has been maintaining safe, stable temperatures and power, but has suspended its science observations and its service as a communications relay for Mars rovers. Normal voltage has been restored, and the spacecraft is being monitored continuously until the troubleshooting is complete.

It appears that all is under control. If MRO goes down, however it will a big loss for Mars research, as the spacecraft not only produces the highest resolution images of the ground, it also acts as one of several communications satellites between the Earth and the rovers on Mars. With two rovers there now, and at least two more planned for arrival in 2020, the loss of this communications link would be crippling.

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Aligned erosion lines of Perseverance Valley

4:52 am

The uncertainty of science: Last week, while I was flying to Israel, the Opportunity science team announced the discovery of strange aligned erosion lines, what they are calling stone stripes, in Perseverance Valley.

The ground texture seen in recent images from the rover resembles a smudged version of very distinctive stone stripes on some mountain slopes on Earth that result from repeated cycles of freezing and thawing of wet soil. But it might also be due to wind, downhill transport, other processes or a combination.

…On some slopes within the valley, the soil and gravel particles appear to have become organized into narrow rows or corrugations, parallel to the slope, alternating between rows with more gravel and rows with less.

The origin of the whole valley is uncertain. Rover-team scientists are analyzing various clues that suggest actions of water, wind or ice. They are also considering a range of possible explanations for the stripes, and remain uncertain about whether this texture results from processes of relatively modern Mars or a much older Mars.

For those who are regular readers of Behind the Black, you already knew about a variation of this discovery back in November 2017, from my regular rover updates. Then, they discovered aligned groves in the gravel that looked to me like slickensides, erosion patterns produced by glacial activity. The science team told me, however, that they were favoring wind, not ice, as a primary cause, though that conclusion was far from certain.

In the press release last week, they focused more on the aligned erosion patterns in the fine gravel that appear to align perpendicular to the slope. Though they think they have found a comparable Earth-based phenomenon that might explain these patterns, it appears that the science team remains just as unsure of their cause as they are for the rocks.

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