Tag: science

“We have a snow-man!”

12:30 pm

Ultima Thule, the snowman

The quote in the headline comes from Alan Stern, the principle scientist for New Horizons, during today’s press conference revealing the first high resolution images of Ultima Thule. The press release for this conference is now online. The image on the right is a reduced cropped version of the main release image today. If you click on it you can see the full resolution version.

The images reveal that Ultima Thule actually is two objects in contact with each other. In addition, the snowman description is apt, as it has a mottled appearance as if it was shaped roughly and somewhat gently over time. Tiny pebbles and rocks softly came together to form two snowballs that then eventually came to touch and join.

They describe this as the most primitive object ever observed. It is also dark, and red in color, like dark reddish dirt.

More images and data is still coming in, to be released in another press conference tomorrow.

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First faint image of Ultima Thule

8:09 am

Ultima Thule, first image

In anticipation of receiving data from the fly-by just past midnight last night, the New Horizons team has released the image above, taken 24 hours earlier.

Just over 24 hours before its closest approach to Kuiper Belt object Ultima Thule, the New Horizons spacecraft has sent back the first images that begin to reveal Ultima’s shape. The original images have a pixel size of 6 miles (10 kilometers), not much smaller than Ultima’s estimated size of 20 miles (30 kilometers), so Ultima is only about 3 pixels across (left panel). However, image-sharpening techniques combining multiple images show that it is elongated, perhaps twice as long as it is wide (right panel). This shape roughly matches the outline of Ultima’s shadow that was seen in observations of the object passing in front of a star made from Argentina in 2017 and Senegal in 2018.

This object is definitely strangely shaped.

New Horizons is traveling fast, which is why we won’t get good images until practically the instant the fly-by happens. And the first downloads from that fly-by are due to arrive within the next two hours. Keep your fingers crossed that the spacecraft operated as programmed and captured Ultima Thule in all its weird glory.

One point about the sad state of journalism these days. Numerous media publications posted stories last night celebrating that fly-by, as if they knew it was a success. This is bunk. We won’t know what happened until this morning. To imply we do is the hallmark of fake news.

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OSIRIS-REx moves into close orbit with Bennu

4:02 pm

OSIRIS-REx has successfully completed an eight second engine burn to place it into a close orbit with the asteroid Bennu.

Now, the spacecraft will circle Bennu about a mile (1.75 kilometers) from its center, closer than any other spacecraft has come to its celestial object of study. (Previously the closest orbit of a planetary body was in May 2016, when the Rosetta spacecraft orbited about four miles (seven kilometers) from the center of the comet 67P/Churyumov-Gerasimenko.) The comfortable distance is necessary to keep the spacecraft locked to Bennu, which has a gravity force only 5-millionths as strong as Earth’s. The spacecraft is scheduled to orbit Bennu through mid-February at a leisurely 62 hours per orbit.

There is a bit of hype here. Other spacecraft have gotten far closer (NEAR, Hayabusa-1, Hayabusa-2) but then retreated for a variety of reasons. What makes this different is the plan to stay this close while they compile detailed data about Bennu’s surface in preparation for touchdown to grab a sample.

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Juno images volcano plume on Io

1:49 pm

Volcano plume on Io

Using several instruments, the Juno science team has successfully photographed an active volcano plume in Io’s polar regions. Two instruments measured the plume’s heat and radiation. Juno’s cameras meanwhile took the color image on the right. The bright spot on Io’s night side matches the location of the heat and radiation signatures from the other instruments.

JunoCam acquired the first images on Dec. 21 at 12:00, 12:15 and 12:20 coordinated universal time (UTC) before Io entered Jupiter’s shadow. The Images show the moon half-illuminated with a bright spot seen just beyond the terminator, the day-night boundary. “The ground is already in shadow, but the height of the plume allows it to reflect sunlight, much like the way mountaintops or clouds on the Earth continue to be lit after the sun has set,” explained Candice Hansen-Koharcheck, the JunoCam lead from the Planetary Science Institute.

This image is not the first time a spacecraft has caught an active volcanic plume on Io. In fact, practically the very first good images of Io during the Voyager 1 fly-by did this, confirming then that volcanoes are active on the Jupiter moon.

What this image further confirms however is how active Io really is. Volcanoes erupt there so continuously that it apparently isn’t that hard to catch one as it happens.

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Engineers adjust Chang’e-4’s orbit

7:39 am

The new colonial movement: Engineers have adjusted Chang’e-4’s lunar orbit in preparation for landing.on the Moon’s far side.

The probe has entered an elliptical lunar orbit, with the perilune at about 15 km and the apolune at about 100 km, at 8:55 a.m. Beijing Time, said CNSA.

Since the Chang’e-4 entered the lunar orbit on Dec. 12, the ground control center in Beijing has trimmed the probe’s orbit twice and tested the communication link between the probe and the relay satellite Queqiao, or Magpie Bridge, which is operating in the halo orbit around the second Lagrangian (L2) point of the earth-moon system.

The space engineers also checked the imaging instruments and ranging detectors on the probe to prepare for the landing.

They need to time the landing so that it comes down in the Moon’s early morning. This will not only provide better visuals, with shadows to see surface details, but more importantly will give them 14 Earth days before sunset to get settled on the surface and initiate rover operations.

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Why the Drake equation is overrated

5:59 pm

The uncertainty of science: An astrophysicist explains why the Drake equation is useless for predicting the number of alien species in the universe.

While the Drake equation may have spurred the early scientific discussion of the search for extraterrestrial intelligence, it doesn’t have much value beyond that. We can’t use to it further our understanding, and we can’t use it to properly guide our thinking. The huge uncertainties in the parameters, the unknown ways those uncertainties mix, and the absolute lack of any guidance in even choosing those parameters robs it of any predictive power. Prediction is at the heart of science. Prediction is what makes an idea useful. And if an idea isn’t useful, why keep it around?

I just wish this same logic was applied to all climate models. They are as useless. Their own huge uncertainties have made them utterly unable to predict anything, for decades. Yet, despite this ongoing failure, vast amounts of research money continues to be poured into the cottage industry that produces them. Worse, too many people in both the intellectual and journalist communities take them far too seriously.

It is a tragedy that is hurting science badly.

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Nancy Roman passes away at 93

8:37 am

R.I.P. Nancy Roman, NASA’s first chief astronomer, died on Christmas at the age of 93.

Her name is largely forgotten, but her support for building the Hubble Space Telescope in the 1960s and the 1970s was critical in getting it done. As important, her support for all in-space astronomy in these early years eventually made it possible. During her term NASA built and launched the first space telescopes. Some were duds. Some were incredible successes. Regardless, her leadership proved that astronomy in space made sense, leading to the achievements that have followed in the half century that has followed.

God speed, Nancy Roman.

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Japan quits global whaling regulatory body

8:41 am

Japan yesterday announced that it is quitting the International Whaling Commission, a global whaling regulatory body founded shortly after World War II to regulate commercial whaling that has instead in recent years attempted to ban all commercial whaling, except for favored native tribes in Russia and the Arctic.

The article’s last few paragraphs provide the real political background to this move by Japan:

An IWC-Japan divorce is the culmination of a wide ideological divide at the commission between ardent anti-whaling nations and countries seeking recognition of limited commercial whaling activities as legitimate. The anti-whaling forces have the upper hand, even though IWC’s expansion has seen more pro-whaling countries joining in recent years.

At the Brazil gathering, Japan had attempted to nudge the IWC toward reforms that would have potentially paved the way for a resumption of commercial whaling. The IWC was initially established to regulate whaling but has enforced an outright moratorium on commercial whaling operations since the 1980s in a desperate bid to prevent the extinction of several whale species. Many whale species have since recovered to a degree, but a few are still considered endangered.

Japan’s reform push was easily voted down. Instead, a majority of IWC members voted to have the commission turn its back on commercial whaling for good. That successful resolution also condemned Japan’s scientific whaling practices, widely regarded as a clandestine commercial operation as Japan’s whaling fleet takes hundreds of whales each year, with the meat ending up in grocery stores and restaurants.

IWC also approved subsistence whale hunts for Arctic aboriginal communities.

The large Japanese delegation at Brazil didn’t hide its frustration. The government accuses IWC members of hypocrisy for allowing culture exemptions from the moratorium for Alaskan and Russian native groups, but not for Japan and Scandinavian whaling cultures.

In other words, this commission has become increasingly political. Rather than focusing on protecting whale populations while allowing whaling by all parties, it has decided to pick and choose who can whale, and has decided to ban Japan while giving others the right to whale.

This political bias is not much different than what was seen at the Paris climate accords. Those agreements put odious restrictions on U.S. commercial activity, while putting no restrictions on China and others. It was this political bias, totally divorced from any sincere effort to reduce CO2 emissions, that prompted Trump to exit that agreement.

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Gale Crater dunes: dry and volcanic in origin

8:26 am

Using data from orbit and from the rover Curiosity, scientists have determined that the material in the dunes in Gale Crater that Curiosity has visited are very dry and volcanic in origin.

This dryness is in contrast with the underlying ground, which shows evidence of water. The data also suggests that the material either came from multiple volcanic sources producing different compositions, or some of the sand was somehow changed at a later time.

In other words, the sand in the dunes came from elsewhere.

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Dried mud cracks on Mars?

3:10 pm

Mud cracks on Mars?

Cool image time! The image to the right, cropped and rotated to post here, was one of the uncaptioned photographs in the December Mars Reconnaissance Orbiter (MRO) image release. If you click on the image you can see the entire photograph. I have cropped the most interesting area, though cracks can be seen in other areas in the image.

What we appear to have here is a darker lower valley filled with dried mud, which over time has cracked as it dried. At its edges there appear to be ripples, almost like one sees on the beach as waves wash the shore. The perimeter slopes even show darker streaks as if the water in some places lapped up the slopes, and in others flowed downward into the valley.

Later, several meteorite impacts occurred, the largest of which produced concentric dried cracks on its outside perimeter. This impact also provides a rough idea of the depth of the mud in this valley.

Mud of course suggests that this lower valley once was filled with water. Was it? It is not possible now to come to a firm conclusion, but this image’s location shown by the red dot in the overview map below and to the right, provides a clue that strengthens this hypothesis.
» Read more

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OSIRIS-REx flies over Bennu’s north pole

10:09 am

Bennu's north pole

Cool movie time! OSIRIS-REx has completed its first planned fly-over of Bennu, this time above its north pole, and the science team has released a short movie showing part of that fly-over. I have embedded the movie below the fold.

This series of MapCam images was taken over the course of about four hours and 19 minutes on Dec. 4, 2018, as OSIRIS-REx made its first pass over Bennu’s north pole. The images were captured as the spacecraft was inbound toward Bennu, shortly before its closest approach of the asteroid’s pole. As the asteroid rotates and grows larger in the field of view, the range to the center of Bennu shrinks from about 7.1 to 5.8 miles (11.4 to 9.3 km).

They have four more fly-overs of the asteroid’s poles and equator as they assemble a detailed map of its surface.
» Read more

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New asteroid radar images

12:59 pm

near-Earth asteroid 2003 SD220

Cool radar images! The set of radar images above of near-Earth asteroid 2003 SD220 were created by combining radar data from three different radar telescopes on Earth, Arecibo in Puerto Rico, Green Bank in West Virginia, and Goldstone in California. As the press release notes:

The asteroid will fly safely past Earth on Saturday, Dec. 22, at a distance of about 1.8 million miles (2.9 million kilometers). This will be the asteroid’s closest approach in more than 400 years and the closest until 2070, when the asteroid will safely approach Earth slightly closer.

The radar images reveal an asteroid with a length of at least one mile (1.6 kilometers) and a shape similar to that of the exposed portion of a hippopotamus wading in a river.

The images have a resolution of 12 feet per pixel, so a close look should be able to reveal any large boulders, should they exist. Instead, I see a soft surface that to me resembles the surface of a sand dune, floating unattached to anything in space.

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No rotational light curve from Ultima Thule?

8:55 pm

Data from New Horizons as it is quickly approaching Ultima Thule has found that even though the object is expected to be oblong or even two objects it has shown absolutely no variation in light as it rotates.

Even though scientists determined in 2017 that the Kuiper Belt object isn’t shaped like a sphere – that it is probably elongated or maybe even two objects – they haven’t seen the repeated pulsations in brightness that they’d expect from a rotating object of that shape. The periodic variation in brightness during every rotation produces what scientists refer to as a light curve.

“It’s really a puzzle,” said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute. “I call this Ultima’s first puzzle – why does it have such a tiny light curve that we can’t even detect it? I expect the detailed flyby images coming soon to give us many more mysteries, but I did not expect this, and so soon.”

They have several theories, all implausible, to explain this. It could be they are looking at the object’s pole. Or maybe a dust cloud or numerous tumbling moons surround the object and hide the light variation.

Fortunately, we shall have an answer to this mystery in less than two weeks, when New Horizons zips past.

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InSight installs seismometer on Martian surface

8:39 am

InSight has successfully placed its first instrument, its seismometer, on Martian surface.

They aren’t yet ready to start gathering data, however.

In the coming days, the InSight team will work on leveling the seismometer, which is sitting on ground that is tilted 2 to 3 degrees. The first seismometer science data should begin to flow back to Earth after the seismometer is in the right position.

But engineers and scientists at JPL, the French national space agency Centre National d’Études Spatiales (CNES) and other institutions affiliated with the SEIS team will need several additional weeks to make sure the returned data are as clear as possible. For one thing, they will check and possibly adjust the seismometer’s long, wire-lined tether to minimize noise that could travel along it to the seismometer. Then, in early January, engineers expect to command the robotic arm to place the Wind and Thermal Shield over the seismometer to stabilize the environment around the sensors.

They plan on deploying the heat probe (which will drill down about 16 feet) in January.

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Curiosity’s future travels

2:11 pm

MRO image of Curiosity's future travels

In the December release of images from the high resolution camera on Mars Reconnaissance Orbiter (MRO), there was one image entitled “Monitor Region Near Curiosity Rover.” To the right is a reduced, cropped, and rotated section of that image, annotated by me to show Curiosity’s future planned route (indicated by the yellow line). If you click on the image you can see the untouched full resolution version.

Curiosity’s journey has not yet brought it onto the terrain shown in this image. (For the overall context of Curiosity’s travels, see Pinpointing Curiosity’s location in Gale Crater.) The rover is right now just off the left edge of the photograph, on the white ridge dubbed Vera Rubin Ridge visible in the uppermost left. This week it completed the last planned drill sampling on that ridge, and it will soon descend off the ridge and begin heading along the yellow route up the mountain. The white dots along its future route are the locations of recurring slope lines, believed to be seasonal seeps of brine coming from below and causing gentle landslides that darken the surface. As you can see, they hope to get very close to the first seep, and will observe the second from across the canyon from a distance of about 1,200 feet.

The peak of Mount Sharp is quite a distance to the south, far beyond the bottom of the photograph. Even in these proposed travels the rover will remain in the mountain’s lowest foothills, though the terrain will be getting considerably more dramatic.

Below is a full resolution section of the image showing the spectacular canyon to the south of that second seep. This is where Curiosity will be going, a deep canyon about 1,500 feet across and probably as deep, its floor a smooth series of curved layers, reminiscent of The Wave in northern Arizona. The canyon appears to show evidence of water flow down its slopes, but that is unproven.
» Read more

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BepiColombo begins first operational engine burn

9:09 am

The European/Japanese mission to Mercury has begun the first operational firing of its four ion engines, set to last for the next two months.

This might seem like a ridiculously long burn, since most conventional rocket engines fire for minutes, not months. These are ion engines, however, far more efficient but producing a very tiny acceleration. It takes a long time for their burns to accumulate a velocity change.

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Comparing Ryugu and Bennu

9:30 am

Link here. As much as they are alike, which is not surprising as they both come from the same asteroid family, the article notes the surprising differences.



Both asteroids are also liberally strewn with boulders – a challenge to mission planners on each team, who hope to descend close enough to scoop up samples for return to Earth. “It’s certainly more rugged than we had expected,” Lauretta says. 

But while boulders on Ryugu look to be unpleasantly ubiquitous, Bennu’s terrain is more varied, with more-obvious places where a safe touchdown might be possible. And, Lauretta notes, the OSIRIS-REx spacecraft is only recently arrived.

“We have a long time to explore and make the crucial decisions about where to go,” he says.

The biggest difference has to do with water. Even though scientists believe them to be portions of the same parent body, which broke apart between 800 million and one billion years ago, Bennu appears to be water rich, while Ryugu is less so. Within a week of arrival, infrared spectrometers on OSIRIS-REx were finding evidence of water-bearing minerals, and not just in localised patches. “We saw this in every single one of the spectra we have taken to date,” says Amy Simon, of NASA’s Goddard Space Flight Centre in Greenbelt, Maryland. 

One of the reasons Bennu was chosen as OSIRIS-REx’s target, Lauretta says, was the hope it would be rich in water, and possibly in organic compounds.

The similarities and differences in the samples both spacecraft will bring back will be most revealing.

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New Horizons sees no hazards, will do closest fly-by of Ultima Thule

9:04 am

After three weeks of intense observations and seeing no significant objects orbiting close to the Kuiper Belt object Ultima Thule, the New Horizons team has decided to go for the closest fly-by on January 1, 2019.

After almost three weeks of sensitive searches for rings, small moons and other potential hazards around the object, New Horizons Principal Investigator Alan Stern gave the “all clear” for the spacecraft to remain on a path that takes it about 2,200 miles (3,500 kilometers) from Ultima, instead of a hazard-avoiding detour that would have pushed it three times farther out. With New Horizons blazing though space at some 31,500 miles (50,700 kilometers) per hour, a particle as small as a grain of rice could be lethal to the piano-sized probe.

We should begin to see more detailed images soon. Because of the speed in which New Horizons is traveling, it will not get very close until it is almost on top of Ultima Thule, so the best images will all occur over a very short span of time.

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Saturn’s rings are dying

8:56 am

Using new ground-based observations, scientists now predict that Saturn’s rings are dying at the fastest predicted rate, and will disappear within 300 million years, at the most.

Dr Tom Stallard, Associate Professor in Planetary Astronomy at the University of Leicester and Dr James O’Donoghue, who studied for his PhD at the University of Leicester, have found that Saturn’s rings are dying at the maximum rate estimated from Voyager 1 and 2 observations made decades ago.

The rings of ice are being pulled into Saturn by gravity as particles of ice under the influence of Saturn’s magnetic field. Dr O’Donoghue, who now works at NASA’s Goddard Space Flight Center in Greenbelt, Maryland said: “We estimate that this ‘ring rain’ drains the equivalent of an Olympic-sized swimming pool from Saturn’s rings in half an hour. The entire ring system will be gone in 300 million years.”

Dr O’Donoghue believes that the rings could even disappear quicker than this. “Add to this the Cassini-spacecraft detected ring-material falling into Saturn’s equator, and the rings have less than 100 million years to live.”

Over the decades I have read numerous papers by scientists saying that rings this bright and large must be a relatively short-lived event, and that we are lucky to have seen them. This research only reinforces this conclusion.

At the same time, we do not yet know the frequency or the cause of the events that give rise such bright rings. It could be that such rings are short-lived, but happen frequently enough that it is still not rare to see them in any solar system. And we won’t know this until we get a more complete census of many solar systems, seen up-close.

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Astronomers discover most distant solar system object so far

9:17 am

Worlds without end: Astronomers have discovered a dwarf planet about 300 miles in diameter orbiting the Sun at a distance of 120 astronomical units, making it the most distant solar system object discovered so far.

“2018 VG18 is much more distant and slower moving than any other observed Solar System object, so it will take a few years to fully determine its orbit,” said Sheppard. “But it was found in a similar location on the sky to the other known extreme Solar System objects, suggesting it might have the same type of orbit that most of them do. The orbital similarities shown by many of the known small, distant Solar System bodies was the catalyst for our original assertion that there is a distant, massive planet at several hundred AU shepherding these smaller objects.”

“All that we currently know about 2018 VG18 is its extreme distance from the Sun, its approximate diameter, and its color,” added Tholen “Because 2018 VG18 is so distant, it orbits very slowly, likely taking more than 1,000 years to take one trip around the Sun.”

I guarantee there are more of these discoveries to come. Many more.

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Two dead at U.S. Antarctic station

1:12 pm

An accident of some kind has apparently killed two individuals at the U.S. McMurdo station in Antarctica yesterday.

The National Science Foundation says two technicians working on a fire-suppression system at an Antarctica scientific station were found unconscious and died.

The foundation said Wednesday the two had been working in a building at McMurdo Station, which is on Ross Island. It says they were found on the floor by a helicopter pilot who had landed after spotting what appeared to be smoke from the building.

Nothing more is as yet known.

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Trace Gas Orbiter finds no methane on Mars

11:31 am

The uncertainty of science: Europe’s Trace Gas Orbiter (TGO) has failed to detect any methane in Mars’ atmosphere, even though data from Mars Express in 2004 had said it should see some.

The Mars Express orbiter first detected hints of methane in the martian atmosphere in 2004. But some scientists said the orbiter’s instruments that found it—at a level of 10 parts per billion (ppb)—weren’t sensitive enough to produce reliable results. Ten years later, NASA’s Curiosity rover detected a methane spike of 7 ppb from its base in Gale crater, which lasted several months. Several years later, Curiosity’s scientists then discovered a minute seasonal cycle, with methane levels peaking at 0.7 ppb in the late northern summer.

To settle this mystery, the European Space Agency’s Trace Gas Orbiter (TGO), which arrived at Mars in 2016, this year began to scan the atmosphere for methane. Two of the TGO’s spectrometers—a Belgian instrument called NOMAD and a Russian one called ACS—were designed to detect methane in such low concentrations that researchers were sure they would. Both instruments, which analyze horizontal slices of the martian atmosphere backlit by the sun, are working well, scientists on the team said today at a semiannual meeting of the American Geophysical Union in Washington, D.C. There’s still some noise to clean up, said Ann Carine Vandaele, NOMAD’s principal investigator and a planetary scientist at the Royal Belgian Institute for Space Aeronomy in Brussels, in her talk. “But we already know we can’t see any methane.”

The team’s initial results show no detection of methane down to a minute level of 50 parts per trillion, with their observations going down nearly all the way to the martian surface.

The data says that any methane seen on the surface (such as by Curiosity) must be coming from below, not from off world, which in itself is a surprise since the scientists expected some methane to be coming from interplanetary dust. TGO has found none..

There are a lot of uncertainties still, so stay tuned.

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Cats might be larger now than in the past

10:44 am

The uncertainty of science: A careful analysis of cat bones from numerous Viking archeology sites going back 2000 years suggests that the size of cats increased during those centuries.

After carefully measuring the bones with an electronic caliper, Bitz-Thorsen and Gotfredsen compared them with those of modern Danish cats dating from 1870 to the present. On average, domesticated cats grew by about 16% between the Viking Age and today, they report this month in the Danish Journal of Archaeology.

The study only focused on Danish cats, so the findings may not be generalizable to other parts of the world. However, a 1987 study of a collection of cat bones from Germany bolsters the idea that domestic cats of the medieval age were smaller than modern-day pets.

They think the size increase was due to better food.

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R.I.P. Riccardo Giacconi

10:13 am

The astronomy community is mourning the passing of Riccardo Giacconi, a pioneer in space X-ray astronomy as well as the first director of the Space Telescope Science Institute, which operates Hubble.

What made him an especially interesting man is that he initially strongly opposed Hubble, preferring the money be spent on X-ray space telescopes. When, during the writing of The Universe in a Mirror, I asked him what prompted his change of opinion that made him head of Hubble, he explained that he felt he “wasn’t being used.” The money for X-ray astronomy just wasn’t there, and rather than chase rainbows he decided to hitch his wagon to something that was certain to produce new science.

The irony is that it was Hubble’s success that probably helped generate the funding for later X-ray space telescopes, such as Chandra.,

Giacconi was a unique and brilliant man. His early X-ray instruments were built by a private commercial company he ran, not a university or NASA. In a sense he was following the classic and older American model here that was abandoned in the 1970s, and is only now beginning to see a resurgence.

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OSIRIS-REx finds evidence of water on Bennu

12:01 am

Bennu from 15 miles

One of OSIRIS-REx’s instruments has now found evidence of water on the rubble-pile asteroid Bennu.

Recently analyzed data from NASA’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) mission has revealed water locked inside the clays that make up its scientific target, the asteroid Bennu.

During the mission’s approach phase, between mid-August and early December, the spacecraft traveled 1.4 million miles (2.2 million km) on its journey from Earth to arrive at a location 12 miles (19 km) from Bennu on Dec. 3. During this time, the science team on Earth aimed three of the spacecraft’s instruments towards Bennu and began making the mission’s first scientific observations of the asteroid. OSIRIS-REx is NASA’s first asteroid sample return mission.

Data obtained from the spacecraft’s two spectrometers, the OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) and the OSIRIS-REx Thermal Emission Spectrometer (OTES), reveal the presence of molecules that contain oxygen and hydrogen atoms bonded together, known as “hydroxyls.” The team suspects that these hydroxyl groups exist globally across the asteroid in water-bearing clay minerals, meaning that at some point, Bennu’s rocky material interacted with water. While Bennu itself is too small to have ever hosted liquid water, the finding does indicate that liquid water was present at some time on Bennu’s parent body, a much larger asteroid.

The image on the right, reduced to show here, was created from 12 images taken on December 2, 2018 from about 15 miles. If you click on the image you can see the full resolution photograph, which is quite incredible. While the asteroid’s shape is approximately what was expected from ground-based observations and computer modeling, the giant boulder on the limb on the bottom right is about four times bigger than expected.

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Voyager 2 enters interstellar space

11:34 am

The Voyager 2 spacecraft, launched in 1977, has entered interstellar space, becoming the second human spacecraft to achieve this.

Comparing data from different instruments aboard the trailblazing spacecraft, mission scientists determined the probe crossed the outer edge of the heliosphere on Nov. 5. This boundary, called the heliopause, is where the tenuous, hot solar wind meets the cold, dense interstellar medium. Its twin, Voyager 1, crossed this boundary in 2012, but Voyager 2 carries a working instrument that will provide first-of-its-kind observations of the nature of this gateway into interstellar space.

Voyager 2 now is slightly more than 11 billion miles (18 billion kilometers) from Earth. Mission operators still can communicate with Voyager 2 as it enters this new phase of its journey, but information – moving at the speed of light – takes about 16.5 hours to travel from the spacecraft to Earth. By comparison, light traveling from the Sun takes about eight minutes to reach Earth.

When I first wrote about these spacecraft in the 1990s, it was thought that Voyager 2 would probably not exit the solar system until the 2020s, meaning that its nuclear power source might die before that happened. That it has happened now, so much earlier, helps map the size of the heliosphere as well as the pressure that might be placed upon it by the interstellar medium

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New Horizons completes another course correction before flyby

11:53 pm

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.

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