Tag: science

The size of Pluto pinned down

12:59 pm

Data from New Horizons has allowed scientists to more firmly determine, for the first time, Pluto’s precise size.

Mission scientists have found Pluto to be 1,473 miles (2,370 kilometers) in diameter, somewhat larger than many prior estimates. Images acquired with the Long Range Reconnaissance Imager (LORRI) were used to make this determination. This result confirms what was already suspected: Pluto is larger than all other known solar system objects beyond the orbit of Neptune. “The size of Pluto has been debated since its discovery in 1930. We are excited to finally lay this question to rest,” said mission scientist Bill McKinnon, Washington University, St. Louis.

Pluto’s newly estimated size means that its density is slightly lower than previously thought, and the fraction of ice in its interior is slightly higher. Also, the lowest layer of Pluto’s atmosphere, called the troposphere, is shallower than previously believed.

This means that Pluto is at this moment the largest Kuiper Belt object so far known, bigger than Eris, the Kuiper Belt planet discovered in 2005 that had been thought to be bigger than Pluto and whose existence was used by some to demote Pluto’s status as a planet.

I say, they are both planets, because they are both heavy enough for gravity to have forced them to become spherical.

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The approaching perihelion of Comet 67P/C-G

9:08 am

The Rosetta science team has prepared a FAQ outlining what we should expect next month as Comet 67P/C-G reaches and passes its closest point to the Sun, with Rosetta (and hopefully Philae) there to watch.

The most interesting detail they note is this:

Will the comet break apart during perihelion?

The comet has not broken apart during its many previous orbits, so it is not expected to do so this time, but it cannot be ruled out. Scientists are keen to watch the possible evolution of a 500 m-long fracture that runs along the surface of the neck on the comet during the peak activity.

You can see an image from Rosetta that shows this fracture here. As I wrote then,

The biggest fracture line appears to be a meandering line that is traveling from the image’s top center to its mid-right. There also appear to be parallel lines below it. As we are looking at the nucleus’s neck, these lines suggest that the connection between the two large lobes is somewhat strained, and that it is not unlikely that these two sections will break apart at some time in the future. Though there is no way to predict at this time when that will happen, it will be truly exciting if it happens when Rosetta is in the neighborhood.

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Pluto on July 11

8:55 am

Pluto on July 11

Another cool image for Monday morning: As the spacecraft zooms towards its Tuesday fly-by, it continues to take images of Pluto, even as the planet rotates. For example, compare today’s image on the right with the one I posted yesterday. You can see some of the same features (the donut-like, crater-like feature is the most obvious), but their positions are different because of the planet’s six-day rotation.

Note also that the row of black spots along the equator show more details. Not unexpectedly, they are not as simple as the early fuzzy images suggested. Unfortunately, we will not get to see even more details, as these features will not be in view during the fly-by.

Update: See this link for a new image of Charon.

More and more to come!

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The last image of Pluto’s opposition hemisphere

11:42 pm

Pluto's opposition hemisphere

Cool image time! The New Horizons team has released the best image they are ever going to get of the hemisphere that will be facing away from the spacecraft when it does its fly-by on July 14.

The spots appear on the side of Pluto that always faces its largest moon, Charon—the face that will be invisible to New Horizons when the spacecraft makes its close flyby the morning of July 14. New Horizons principal investigator Alan Stern of the Southwest Research Institute, Boulder, Colorado, describes this image as “the last, best look that anyone will have of Pluto’s far side for decades to come.”

The spots are connected to a dark belt that circles Pluto’s equatorial region. What continues to pique the interest of scientists is their similar size and even spacing. “It’s weird that they’re spaced so regularly,” says New Horizons program scientist Curt Niebur at NASA Headquarters in Washington. Jeff Moore of NASA’s Ames Research Center, Mountain View, California, is equally intrigued. “We can’t tell whether they’re plateaus or plains, or whether they’re brightness variations on a completely smooth surface.”

No one will likely have the answers to these questions for a long time, as it might take as long as a half century before before anyone can get another spacecraft there.

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Ceres’ white spots might be salt not water

6:16 pm

The uncertainty of science: The principal investigator of Dawn has indicated that the preliminary data they have gotten of Ceres’ white spots strongly suggests that they are not water but salt.

The mystery is far from completely solved, Russell cautioned. The team failed to get the quality of measurements they wanted in examining the spots, and they’ll have to try again at a closer orbit — like the next planned mapping orbit, which will take them from 2,700 miles over the surface to just 900. The photos taken at that height will also have significantly better resolution, which should further help the team determine what the spots are made of.

But based on the spectral data the team did get, Russell said, the spots “really don’t look like mounds of ice. … The bright spots are probably — like you might find in the desert on Earth — a salt plain where maybe water came out at one time and evaporated,” Russell said.

None of this is confirmed, and won’t be until they lower Dawn’s orbit to get higher resolution images. However, this must wait because they have extended Dawn’s mapping orbit for now as they review the issue that caused the safe mode incident on June 30.

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Another new Pluto image

6:02 pm

Pluto geology

Cool image time! The New Horizons science team released another image of Pluto on Friday, this time showing enough details that they can begin to see geological features.

New Horizons’ latest image of Pluto was taken on July 9, 2015 from 3.3 million miles (5.4 million kilometers) away, with a resolution of 17 miles (27 kilometers) per pixel. At this range, Pluto is beginning to reveal the first signs of discrete geologic features. This image views the side of Pluto that always faces its largest moon, Charon, and includes the so-called “tail” of the dark whale-shaped feature along its equator. (The immense, bright feature shaped like a heart had rotated from view when this image was captured.)

“Among the structures tentatively identified in this new image are what appear to be polygonal features; a complex band of terrain stretching east-northeast across the planet, approximately 1,000 miles long; and a complex region where bright terrains meet the dark terrains of the whale,” said New Horizons principal investigator Alan Stern.

Be sure to click on the link to see the full resolution version of the image.

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The incivility and hostility of the Mauna Kea protesters

11:07 am

The management of Mauna Kea has released event logs by both their rangers [pdf] and the visitor center [pdf], outlining the generally hostile and illegal behavior of the TMT protesters during the past four months, including threats of violence against visiters and workers to the mountain.

The news story above does not really give the full flavor of the protesters’ generally rude and hostile behavior. They repeatedly threatened workers and visitors, damaged both existing facilities as well as the natural environment on which they camped illegally, and interfered with others who had come to the mountain to star-gaze or work. The logs also include numerous examples of the protesters exhibiting incredible ignorance about the astronomy on the mountain as well as the Thirty Meter Telescope itself. If you get the chance, read these logs yourself. They clarify for everyone which side stands on the side of civilization and which does not.

Finally there is this important tidbit:

From March 24, 2015 through present, groups of protesters, some up to nearly 200 persons, have sporadically been onsite on the University of Hawaii management lands and DLNR lands on Maunakea. A group of about 10 protesters has maintained a continuous presence day and night. [emphasis mine]

As is usual for protests like this, the actual numbers are miniscule, and are magnified by a press that wants to promote the protesters’ agenda, even though a very large majority does not agree with that agenda.

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Juno flight plan at Jupiter revised

10:16 am

In preparation for its arrival in orbit around Jupiter in about a year, engineers for the unmanned probe Juno have revised their planned orbital maneuvers.

Following a detailed analysis by the Juno team, NASA recently approved changes to the mission’s flight plan at Jupiter. Instead of taking 11 days to orbit the planet, Juno will now complete one revolution every 14 days. The difference in orbit period will be accomplished by having Juno execute a slightly shorter engine burn than originally planned.

The revised cadence will allow Juno to build maps of the planet’s magnetic and gravity fields in a way that will provide a global look at the planet earlier in the mission than the original plan. Over successive orbits, Juno will build a virtual web around Jupiter, making its gravity and magnetic field maps as it passes over different longitudes from north to south. The original plan would have required 15 orbits to map these forces globally, with 15 more orbits filling in gaps to make the map complete. In the revised plan, Juno will get very basic mapping coverage in just eight orbits. A new level of detail will be added with each successive doubling of the number, at 16 and 32 orbits.

The change will extend the official mission from 15 to 20 months, though I expect that even this will be extended if the spacecraft’s fuel holds out.

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New radio communications from Philae

9:35 am

On July 9 Philae successfully transmitted data to Rosetta for the first time in more than two weeks.

Although the connection failed repeatedly after that, it remained completely stable for those 12 minutes. “This sign of life from Philae proves to us that at least one of the lander’s communication units remains operational and receives our commands,” said Koen Geurts, a member of the lander control team at DLR Cologne.

The mood had been mixed over the last few days; Philae had not communicated with the team in the DLR Lander Control Center (LCC) since 24 June 2015. After an initial test command to turn on the power to CONSERT on 5 July 2015, the lander did not respond. Philae’s team began to wonder if the lander had survived on Comet 67P/Churyumov-Gerasimenko.

The intermittent nature of Philae’s attempts at communication are puzzling. Normally, they either would have communications or they would not. For good communications to break off like this repeatedly is puzzling. It is almost as if there is a loose wire causing communications to go on and off, which seems an unlikely explanation for this problem.

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New image of Pluto and Charon

12:02 am

Pluto and Charon

The New Horizons science team today released a new image showing both Pluto and Charon, and not unexpectedly, they are very different from each other.

A high-contrast array of bright and dark features covers Pluto’s surface, while on Charon, only a dark polar region interrupts a generally more uniform light gray terrain. The reddish materials that color Pluto are absent on Charon. Pluto has a significant atmosphere; Charon does not. On Pluto, exotic ices like frozen nitrogen, methane, and carbon monoxide have been found, while Charon’s surface is made of frozen water and ammonia compounds. The interior of Pluto is mostly rock, while Charon contains equal measures of rock and water ice. “These two objects have been together for billions of years, in the same orbit, but they are totally different,” said Principal Investigator Alan Stern of the Southwest Research Institute (SwRI), Boulder, Colorado.

For a half century, since the first probes left Earth to visit other worlds, the one consistent axiom we have learned from every mission is that no two objects are going to be alike, and that every object out there is going to be incredibly unique. Pluto and Charon, in finishing the human race’s first inventory of the solar system, prove this axiom once again.

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A bullseye in space

11:18 am

Cool image time! The science team of the Swift space telescope has released a movie compiled from X-ray images taken of the first outburst from black hole V404 Cygni in 26 years. [link fixed!]

Astronomers say the rings result from an “echo” of X-ray light. The black hole’s flares emit X-rays in all directions. Dust layers reflect some of these X-rays back to us, but the light travels a longer distance and reaches us slightly later than light traveling a more direct path. The time delay creates the light echo, forming rings that expand with time.

Detailed analysis of the expanding rings shows that they all originate from a large flare that occurred on June 26 at 1:40 p.m. EDT. There are multiple rings because there are multiple reflecting dust layers between 4,000 and 7,000 light-years away from us. Regular monitoring of the rings and how they change as the eruption continues will allow astronomers to better understand their nature.

V404 Cygni is located about 8,000 light-years away. Every couple of decades the black hole fires up in an outburst of high-energy light. Its previous eruption ended in 1989.

The animation below the fold is a smaller resolution version of the movie, showing the rings as they expand outward.
» Read more

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A new double dynamo theory to explain the Sun’s solar cycle

10:45 am

A team of solar scientists have proposed a new theory that they think explains the ebb and flow of the Sun’s eleven year solar cycle, and if right can explain the periodic occurrence of grand minimums where there are essentially no sunspots for decades, such as the Maunder Minimum in the 1600s.

The theory proposes that the Sun has two different dynamos that produce different magnetic waves in its interior. Like waves that can either cancel each other out or combine for more power, these two dynamos do the same over time and thus effect the Sun’s sunspot/solar cycle.

“We found magnetic wave components appearing in pairs, originating in two different layers in the Sun’s interior. They both have a frequency of approximately 11 years, although this frequency is slightly different, and they are offset in time. Over the cycle, the waves fluctuate between the northern and southern hemispheres of the Sun. Combining both waves together and comparing to real data for the current solar cycle, we found that our predictions showed an accuracy of 97%,” said Zharkova.

Zharkova and her colleagues derived their model using a technique called ‘principal component analysis’ of the magnetic field observations from the Wilcox Solar Observatory in California. They examined three solar cycles-worth of magnetic field activity, covering the period from 1976-2008. In addition, they compared their predictions to average sunspot numbers, another strong marker of solar activity. All the predictions and observations were closely matched.

Looking ahead to the next solar cycles, the model predicts that the pair of waves become increasingly offset during Cycle 25, which peaks in 2022. During Cycle 26, which covers the decade from 2030-2040, the two waves will become exactly out of synch and this will cause a significant reduction in solar activity.

“In cycle 26, the two waves exactly mirror each other – peaking at the same time but in opposite hemispheres of the Sun. Their interaction will be disruptive, or they will nearly cancel each other. We predict that this will lead to the properties of a ‘Maunder minimum’,” said Zharkova. “Effectively, when the waves are approximately in phase, they can show strong interaction, or resonance, and we have strong solar activity. When they are out of phase, we have solar minimums. When there is full phase separation, we have the conditions last seen during the Maunder minimum, 370 years ago.”

And on this same subject, last week NOAA posted its monthly update of the solar cycle, showing the Sun’s sunspot activity in June. As I have done every month since 2010, I am posting it here, below the fold, with annotations to give it context.
» Read more

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Watch Opportunity’s full journey on Mars, in 8 minutes

9:54 am

The science team for the Mars rover Opportunity have released an 8-minute movie compiled from the rover’s hazard-avoidance cameras. Enjoy!

One comment: There is a long stretch of territory south of Albuquerque, New Mexico called Jornada de Muerto, which means “Journey of Death” in English. It gets its name from its lack of water or life. This video makes that stretch of land look like a water park, strongly highlighting the utter barrenness of the Martian surface.

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Best image yet of Pluto

9:29 am

Pluto

Very cool image time! The New Horizons science team today released [link fixed] their best image yet of Pluto, taken on July 7 immediately following the spacecraft’s recovery from safe mode.

This view is centered roughly on the area that will be seen close-up during New Horizons’ July 14 closest approach. This side of Pluto is dominated by three broad regions of varying brightness. Most prominent are an elongated dark feature at the equator, informally known as “the whale,” and a large heart-shaped bright area measuring some 1,200 miles (2,000 kilometers) across on the right. Above those features is a polar region that is intermediate in brightness.

For the first time these features look like actual surface areas on a planet, not fuzzy blobs. We are still seeing Pluto like we saw all planets prior to the space age, but at least now we know what we are looking at.

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Dance of the stars

8:51 am

Astronomers have found a stellar system made up of five stars, two binary systems orbiting each other, with a fifth star orbiting one of the stars in one of the binaries.

Co-author Dr Markus Lohr, from the Open University, told BBC News that these contact binaries were stars that orbit so closely they share an outer atmosphere. The other star pair – a detached binary – has a separation distance of some three million km. The two binaries orbit in the same plane at a distance of 21 billion km.

Follow-up observations of different wavelengths of light coming from the star system uncovered a fifth star, which is linked to the detached binary star. “This is a truly exotic star system. In principle there’s no reason why it couldn’t have planets in orbit around each of the pairs of stars. Any inhabitants would have a sky that would put the makers of Star Wars to shame,” Dr. Lohr said. “There could sometimes be no fewer than five Suns of different brightnesses lighting up the landscape.”

Dr. Lohr is being a bit extravagant. Though planets are a possibility here, I suspect it very unlikely that they are habitable.

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A New Horizons map of Pluto

11:54 pm

New Horizons map of Pluto

Cool image time! The New Horizons science team today released their best global map of Pluto, as seen so far.

The center of the map shows the area that New Horizons will see close-up during the fly-by.

The elongated dark area informally known as “the whale,” along the equator on the left side of the map, is one of the darkest regions visible to New Horizons. It measures some 1,860 miles (3,000 kilometers) in length. Directly to the right of the whale’s “snout” is the brightest region visible on the planet, which is roughly 990 miles (1,600 kilometers) across. This may be a region where relatively fresh deposits of frost—perhaps including frozen methane, nitrogen and/or carbon monoxide—form a bright coating.

Continuing to the right, along the equator, we see the four mysterious dark spots that have so intrigued the world, each of which is hundreds of miles across. Meanwhile, the whale’s “tail,” at the left end of the dark feature, cradles a bright donut-shaped feature about 200 miles (350 kilometers) across. At first glance it resembles circular features seen elsewhere in the solar system, from impact craters to volcanoes. But scientists are holding off on making any interpretation of this and other features on Pluto until more detailed images are in hand.

Some of these features will not be resolved much clearer than this, as Pluto’s day is six Earth days long, and will thus not be visible any longer to the spacecraft during its last week approach. In addition, much of the southern hemisphere will also not be imaged at all, as the planet’s inclination puts much of that hemisphere out of view entirely.

Nonetheless, we will see a great deal that has never been seen before. Stay tuned!

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Brainstorm – the world’s smartest mouse

6:01 pm

An evening pause: You might say this a variation on a Rube Goldberg device, except that instead of gravity running the show it is a mouse.

Hat tip Phill Oltmann.

Readers: I am always looking for tips for my evening pauses. If you see a video you think might fit, make a comment here mentioning that you have something, but don’t post the link. I will email you to get it from you.

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Dawn recovers from safe mode

9:17 am

Spot 1

Beginning on June 30 Dawn experienced an as yet unexplained “anomaly” that put it into safe mode for several days.

According to JPL, engineers have uploaded “configuration changes” that solved the problem, and the spacecraft has returned to normal operations, continuing its second mapping orbit of Ceres. From this position they are gathering wide angle images of the entire planet, from which they will construct a detailed global map to be used as a baseline during later more detailed close-up orbits. For example, they released this very nice image today of what is called “Spot 1”, shown on the right. I have cropped it to focus on the spot itself. Looks almost like scattered snow on the surface, doesn’t it?

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Obamacare continues to cause health insurance premiums to skyrocket

1:06 pm

Finding out what’s in it: Health insurance companies are now requesting (and getting) rate increases from 23 to 54 percent due to the increased costs imposed by Obamacare.

Blue Cross and Blue Shield plans — market leaders in many states — are seeking rate increases that average 23 percent in Illinois, 25 percent in North Carolina, 31 percent in Oklahoma, 36 percent in Tennessee and 54 percent in Minnesota, according to documents posted online by the federal government and state insurance commissioners and interviews with insurance executives.

The Oregon insurance commissioner, Laura N. Cali, has just approved 2016 rate increases for companies that cover more than 220,000 people. Moda Health Plan, which has the largest enrollment in the state, received a 25 percent increase, and the second-largest plan, LifeWise, received a 33 percent increase.

At the same time, many insurance companies are merging or leaving the market because of the law makes profitability impossible.

Obviously, we must all then vote for Democrats so they can use their brilliance (demostrated so clearly with Obamacare) to solve this problem by nationalizing healthcare.

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New Horizons temporarily loses contact with Earth

9:38 am

Engineers lost contact with New Horizons for an hour and twenty-one minutes on Saturday.

Engineers have since begun talking with the probe again, but NASA says it will take up to several days to get New Horizons back to normal. In the meantime, the US$700-million spacecraft is not recording science data. It is just 11 million kilometres from Pluto, and closing in fast.

Communication issues are exacerbated by the fact that it takes four and a half hours to send a signal, traveling at light speed, across the nearly 4.8 billion kilometres to the spacecraft — and four and a half hours back. In that elapsed time, the Earth has rotated so much that mission controllers must switch from one to another of the three deep-space antennas that communicate with spacecraft: in Goldstone, California; Canberra; and Madrid.

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The jets on Comet 67P/C-G come from its sinkholes

10:18 am

More on the comet sinkholes! New data from Rosetta has now confirmed that some of the plumes or jets that the spacecraft has seen emanating from Comet 67P/C-G come directly from the sinkholes that they have discovered on the nucleus.

In a study reported today in the science journal Nature, 18 quasi-circular pits have been identified in the northern hemisphere of the comet, some of which are the source of continuing activity. The pits are a few tens to a few hundreds of metres in diameter and extend up to 210 m below the surface to a smooth dust-covered floor. Material is seen to be streaming from the most active pits. “We see jets arising from the fractured areas of the walls inside the pits. These fractures mean that volatiles trapped under the surface can be warmed more easily and subsequently escape into space,” says Jean-Baptiste Vincent from the Max Planck Institute for Solar System Research, lead author of the study.

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TMT protesters complain about road closure

9:59 am

The leader of the protest that is opposing the construction of the Thirty Meter Telescope (TMT) is now complaining about the road closure imposed by Hawaii’s government that is preventing him and his followers from returning to the mountain.

“The telescope employees have been able to access the mountain every single day to go up and come back down and even we as protectors of the mountain have been given daily access to conduct pule and religious practices on the mountain,” said Kahookahi Kanuha, a member of Ku Kia’i Mauna, which hopes to keep the telescope from being built. “So, if they do deem it unsafe, it is quite irresponsible of them to allow other individuals up the mountain.”

So let me get this straight: He thinks it is wrong for the people who own or lease the mountain — who have legal right to control access — to block the protesters, but he sees nothing wrong with him going there — trespassing — and blocking access to others. What a hypocrite.

This article proves that my analysis from Tuesday is correct. The government has shut the road mainly to quietly get the protesters out of the way and let things cool down. When construction resumes, I guarantee that road access will restricted to prevent the protesters from returning and blocking the road. (Update: The quotes here from the state’s attorney general provide even further confirmation that the state will not allow protests to obstruct future access to construction crews.)

One other note: The author of the first article above uses the typical dishonest mainstream media technique of only quoting one protester, the activist leader, while claiming that “protesters” are objecting. The data in the article, however, does not document this spin. As far as I can tell, the only one complaining about the road closure is this one guy.

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What we will and will not see during the Pluto fly-by

9:32 am

Pluto's two hemispheres

The images above, released today by the New Horizons’ science team, provide the best global view so far of Pluto’s two hemispheres. I have cropped and rearranged the original to focus on Pluto.

The images illustrate some basic new knowledge about the planet. For one, scientists have now identified the planet’s poles, based upon its rotation. While scientists had had a very rough vague idea of Pluto’s rotation and inclination beforehand, they have now pinned it down pretty precisely.

The images also show the planet’s most striking and unique features, though not with enough resolution to tell us what they are.

New color images from NASA’s New Horizons spacecraft show two very different faces of the mysterious dwarf planet, one with a series of intriguing spots along the equator that are evenly spaced. Each of the spots is about 300 miles in diameter, with a surface area that’s roughly the size of the state of Missouri.

Scientists have yet to see anything quite like the dark spots; their presence has piqued the interest of the New Horizons science team, due to the remarkable consistency in their spacing and size. While the origin of the spots is a mystery for now, the answer may be revealed as the spacecraft continues its approach to the mysterious dwarf planet. “It’s a real puzzle—we don’t know what the spots are, and we can’t wait to find out,” said New Horizons principal investigator Alan Stern of the Southwest Research Institute, Boulder. “Also puzzling is the longstanding and dramatic difference in the colors and appearance of Pluto compared to its darker and grayer moon Charon.”

This image release also shows us what we will and will not see during the fly-by. The image on the left is the “encounter hemisphere.” This is the hemisphere that will be in view during New Horizons’ July 14 fly-by. We shall get very nice high resolutions of much of this hemisphere.

The other hemisphere, however, will not be facing us during the fly-by. Unless that can get some high resolution images before it rotates out of view, the row of large dark spots at the equator will remain a mystery.

The images also suggest that, because of Pluto’s tilt, much of the southern hemisphere is not going to be seen at all. It will remain an additional mystery for the many decades that are going to pass before another spacecraft finally returns to this distant place.

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Active sinkholes found on Comet 67P/C-G

11:00 am

pits on Comet 67P/C-G

Cool image time! Using Rosetta’s high resolution camera scientists have located a number of active pits similar to sinkholes on Earth on Comet 67P/C-G.

Based on the Rosetta observations, the team has proposed a model for the formation of these sinkholes. A source of heat beneath the comet’s surface causes ices (primarily water, carbon monoxide and carbon dioxide) to sublimate. The voids created by the loss of these ice chunks eventually grow large enough that their ceilings collapse under their own weight, giving rise to the deep, steep-sided circular pits seen on the surface of comet 67P/Churyumov-Gerasimenko.

The collapse exposes comet ices to sunlight for the first time, which causes the ice chunks to begin sublimating immediately. These deeper pits are therefore thought to be relatively young. Their shallower counterparts, on the other hand, are most likely older sinkholes with more thoroughly eroded sidewalls and bottoms that have been filled in by dust and ice chunks.

Essentially, they have found that decay of the comet’s nucleus has been mostly gentle and steady, rather than explosive, punctuated with sudden abrupt events.

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New Horizons gets closer

11:30 pm

Pluto and Charon

Cool image time! Even as the engineers successfully completed last night their last course correction engine burn, the New Horizons science team released an image showing both Pluto and Charon.

The 23-second thruster burst was the third and final planned targeting maneuver of New Horizons’ approach phase to Pluto; it was also the smallest of the nine course corrections since New Horizons launched in January 2006. It bumped the spacecraft’s velocity by just 27 centimeters per second – about one-half mile per hour – slightly adjusting its arrival time and position at a flyby close-approach target point approximately 7,750 miles (12,500 kilometers) above Pluto’s surface.

The image, which I have cropped to focus on the planets, is still somewhat fuzzy, though it also shows the increasing sharpness as the spacecraft gets closer.

Only two weeks to go!

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Another Dawn image of some of Ceres’ bright spots

10:37 am

The double bright spot, not over-exposed

Cool image time! As part JPL’s regular release of images from Dawn, one image of Ceres’ bright double spots was purposely not over-exposed. Thus, the surface is almost black (as it really looks), while the small cluster of spots stands out brightly but with some additional detail. (If you download the full image and use a graphics program to brighten it you will see that this is the double bright spot located inside a large crater.)

I have cropped and enlarged the original image to focus on the double spot. As you can see the brightest spot has a mottled look, almost like we are looking down at a snow-capped peak.

Though the leading theory remains that this is ice, this theory has not been confirmed yet. Make no assumptions or you may discover you are wrong.

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An update on Rosetta’s effort to re-establish contact with Philae

8:47 am

This update describes the status of the effort by the Rosetta science team to re-establish a stable communications channel with the Philae lander on the surface of Comet 67P/C-G.

Confirmed contacts between Rosetta and Philae have been made on 13, 14, 19, 20, 21, 23, and 24 June, but were intermittent during those contact periods. For example, the contact on 19 June was stable but split into two short periods of two minutes each. Conversely, the contact on 24 June started at 17:20 UT (on board Rosetta) and ran for 20 minutes, but the quality of the link was very patchy and only about 80 packets of telemetry were received. Prior to this, on Tuesday, 23 June, there was a 20-second contact, but no stable link was established and consequently no telemetry data were received.

There are many reasons why the contacts have been so intermittent, much of it related to Philae’s position on the surface. To improve things, they are carefully adjusting Rosetta’s position relative to the comet while avoiding placing the spacecraft in a position where the coma’s dust will cause problems.

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