Tag: science

A star that is devouring its planets?

12:55 pm

Astronomers now think that a nearby star that erratically dims inexplicably does so because of clouds of debris left by the destruction of one or more exoplanets.

A team of U.S. astronomers studying the star RZ Piscium has found evidence suggesting its strange, unpredictable dimming episodes may be caused by vast orbiting clouds of gas and dust, the remains of one or more destroyed planets. “Our observations show there are massive blobs of dust and gas that occasionally block the star’s light and are probably spiraling into it,” said Kristina Punzi, a doctoral student at the Rochester Institute of Technology (RIT) in New York and lead author of a paper describing the findings. “Although there could be other explanations, we suggest this material may have been produced by the break-up of massive orbiting bodies near the star.”

Their data also suggest that the star is young.

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The best infrared image yet of a star’s surface

10:34 am

The surface of a star

Astronomers, using the Very Large Telescope in Chile have taken the best infrared image of the surface of a star, revealing gigantic granules or convection cells, across the star’s surface. These cells are somewhat similar to the bubbles you see when you simmer tomato sauce. Our own Sun usually has about two million such cells across its surface. For this aging red giant, which has the same mass as the Sun but has expanded to 350 times its diameter, things are different.

[The astronomers] found that the surface of this red giant has just a few convective cells, or granules, that are each about 120 million kilometres across — about a quarter of the star’s diameter [2]. Just one of these granules would extend from the Sun to beyond Venus.

I have posted the image on the right, reduced slightly in resolution to show here. The press release says that this is the first time that such granules have been imaged, but I think that is a bit of an overstatement. In fact, one of the very first articles I ever wrote, back in 1994, described an infrared image taken of Betelgeuse that showed similar giant bubbles or cells. What makes this image significant is its improved resolution. The ability to see smaller details on the faces of distant stars continues to improve.

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Two finalists for 2020 deep space planetary mission picked by NASA

1:16 pm

NASA has narrowed its choice for a 2020s deep space planetary mission to two finalists, either a sample return mission to Comet 67P/C-G or a drone that would fly through Titan’s atmosphere.

The sample return mission sounds very doable with today’s technology. The Titan drone mission however is far more intriguing.

Dragonfly is a dual-quadcopter lander that would take advantage of the environment on Titan to fly to multiple locations, some hundreds of miles apart, to sample materials and determine surface composition to investigate Titan’s organic chemistry and habitability, monitor atmospheric and surface conditions, image landforms to investigate geological processes, and perform seismic studies.

If it was up to me and I had unlimited funds, I’d go with Dragonfly. We know far less about the outer solar system, and this mission would be an ideal way to increase that knowledge. It is also far more daring, which carries the risk that the costs to build and launch will rise uncontrollably.

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Oumuamua has a thick carbon crust built up by its interstellar travel

8:59 am

New results of observations of the interstellar object Oumuamua suggest that it has a thick crust of organic carbon soot that was slowly built up during the millions of years it traveled between the stars.

New observations of the cigar-shaped body found evidence for a deep surface layer that formed when organic ices – such as frozen carbon dioxide, methane and methanol – that make up the object were battered by the intense radiation that exists between the stars.

…The deep outer crust may have formed on the body over millions or even billions of years and gives ‘Oumuamua a dark red colour, according to researchers who investigated the object with the William Herschel Telescope on La Palma in the Canary Islands and the European Southern observatory in Chile’s Atacama desert.

There have been a slew of news stories today about these results, all focusing not on the crust of the object, which tells us nothing really about its interior, but on one quote by one scientist from the press release, who theorized — based on zero data — that the interior of the object could be icy. From this quote I have seen at least a half dozen stories exclaiming that Oumuamua thus could be like a comet, based on no information at all.

All we have learned is that traveling for a long time in interstellar space causes a build up of carbon-rich materials on the surface of an object. What might be hidden under that crust remains entirely unknown. It could be icy, but we don’t know that.

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Mars rover update: December 18, 2017

11:44 am

Summary: The scientists and engineers of both Curiosity and Opportunity have route decisions to make.

Curiosity

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

Since my November 16 update, Curiosity’s travels crossing Vera Rubin Ridge, a geological bedding plain dubbed the Hematite Unit, has continued apace. They however have not been following the route that had been planned beforehand, as shown by the yellow dotted line on the right. Instead, they have headed south, along the red dotted line. For the past week or so they have been doing a variety of research tasks in the same area, analyzing samples taken months before, studying sand deposits, and taking many images of some interesting rock layers.

I also suspect that the lack of movement in the past week is partly because they need to make some route-finding decisions. The planned yellow route shown above appears to be somewhat rough in the full resolution orbital image. While I suspect they will still head in that direction, I also think they are doing some very careful analysis of this route and beyond, to make sure they will not end up in a cul de sac where the rover will not be able to continue its climb of Mount Sharp.

Opportunity

For the context of Opportunity’s recent travels along the rim of Endeavour Crater, see my May 15, 2017 rover update.
» Read more

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More films of early nuclear test released

10:52 am

The uncertainty of science: Researchers have released more films taken during numerous 1950s and 1960s atmospheric nuclear bomb tests to the public, while noting that modern computer simulations of nuclear explosions, based on the data taken from these early tests, could be as much as 30 percent in error.

Ten years ago, Spriggs was asked to write a computer code related to nuclear weapons effects, but his calculations didn’t agree with what was published in the 1950s and ’60s. When he dug in to find out why there was a discrepancy, he discovered that the manual measurements made in the ’50s and ’60s were off, in some cases by 20 percent to 30 percent. His new mission had become clear: reanalyze all the nuclear test films to ensure future computer simulations would be validated.

“It was driving me nuts,” Spriggs said. “No matter what I did, I couldn’t get my calculations to agree. Eventually, I came to the conclusion that the data must be off. To prove our simulations are correct, we rely on quality benchmark data. That’s why this project is so important. It is providing the data our physicists need to ensure our deterrent remains viable into the future.”

They are scanning and reanalyzing all the footage so that they can refine their models. They also note that the analysis done in the 50s and 60s was actually quite good, but today’s computer technology allows for greater accuracy and objectivity.

Hat tip Wayne DeVette.

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Initial analysis of radio observations of Oumuamua detect no artificial signals

1:34 pm

The initial analysis of the first set of radio observations of Oumuamua by Breakthrough Listen has so far not detected any artificial signals.

No such signals have been detected, although the analysis is not yet complete. So far, data from the S-band receiver (covering frequencies from 1.7 to 2.6 GHz) has been processed, and analysis of the remaining three bands is ongoing. A subset of the S-band data is now available for public inspection in the Breakthrough Listen archive3, and additional data will be added as it becomes available.

The data is stored in specialized formats, and analyzing it may be challenging for non-experts. We invite those who are interested to study the tutorial material provided by the Breakthrough Listen science team at the University of California, Berkeley, SETI Research Center and to assist with the analysis not only of this intriguing object, but of the entire Breakthrough Listen dataset.

They still plan three more observation sessions.

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New exoplanet makes eight in rival solar system

1:27 pm

comparing solar systems

Worlds without end: Astronomers using Kepler data mined by computers have discovered an eighth planet in another solar system, making that system somewhat comparable to our own.

The newly discovered Kepler-90i — a sizzling hot, rocky planet orbiting its star once every 14.4 days — was found using computers that “learned” to find planets in data from NASA’s Kepler space telescope. Kepler finds distant planets beyond the solar system, or exoplanets, by detecting the minuscule change in brightness when a planet transits (crosses in front of) a star.

Vanderburg, a NASA Sagan fellow at UT Austin, and Shallue, a Google machine learning researcher, teamed up to train a computer to learn how to identify signs of an exoplanet in the light readings from distant stars recorded by Kepler. Similar to the way neurons connect in the human brain, this “neural network” sifted through the Kepler data to identify the weak transit signals from a previously missed eighth planet orbiting Kepler-90, a sun-like star 2,545 light-years from Earth in the constellation Draco. “For the first time since our solar system planets were discovered thousands of years ago, we know for sure that our solar system is not the sole record holder for the most planets,” Vanderburg said.

The image to the right compares the planet sizes between this solar system and ours. It does not show that, for this distant star, all eight planets have orbits closer to the star than the Earth, and would therefore be very unlikely to harbor life.

One more thing: This story is very cool, but it also is another one of those NASA press releases that the agency PR department overhyped beforehand, even allowing some reporters to think that it might involve the discovery of life beyond Earth. Not surprisingly, several news sources and radio shows asked me to talk about it. To their disappointment I said I’d rather wait, since NASA has overhyped more than a few stories like this in recent years. Once again, my instincts were right. This story has nothing to do with alien life, and though interesting, is actually not that big a deal.

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A variety of geological activity caused bright areas on Ceres

10:33 am

Occator Crater

Based on the data obtained of Ceres from Dawn scientists have concluded that a variety of geological activities caused the bright areas on the planet, and that some of those activities could still be happening today.

Since Dawn arrived in orbit at Ceres in March 2015, scientists have located more than 300 bright areas on Ceres. A new study in the journal Icarus, led by Nathan Stein, a doctoral researcher at Caltech in Pasadena, California, divides Ceres’ features into four categories.

The first group of bright spots contains the most reflective material on Ceres, which is found on crater floors. The most iconic examples are in Occator Crater [shown in the image above, reduced and cropped to post here], which hosts two prominent bright areas. Cerealia Facula, in the center of the crater, consists of bright material covering a 6-mile-wide (10-kilometer-wide) pit, within which sits a small dome. East of the center is a collection of slightly less reflective and more diffuse features called Vinalia Faculae. All the bright material in Occator Crater is made of salt-rich material, which was likely once mixed in water. Although Cerealia Facula is the brightest area on all of Ceres, it would resemble dirty snow to the human eye.

More commonly, in the second category, bright material is found on the rims of craters, streaking down toward the floors. Impacting bodies likely exposed bright material that was already in the subsurface or had formed in a previous impact event.

Separately, in the third category, bright material can be found in the material ejected when craters were formed.

The mountain Ahuna Mons gets its own fourth category — the one instance on Ceres where bright material is unaffiliated with any impact crater. This likely cryovolcano, a volcano formed bythe gradual accumulation of thick, slowly flowing icy materials, has prominent bright streaks on its flanks.

The report is somewhat vague about why they think that there might be some geological activity even today.

The image above, released as part of this press release, gives us a simulated oblique look at Occator Crater and its bright areas. It is definitely worth it to look at the full resolution image.

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Saturn’s rings are very young

8:57 am

Data from Cassini’s last ring-diving orbits has now strengthened the hypothesis that Saturn’s rings formed very recently, just a few hundred million years ago.

Saturn acquired its jewels relatively late in life. If any astronomers had gazed at the sky in the time of the dinosaurs, they might have seen a bare and boring Saturn.

It was then that some sort of catastrophe struck the gas giant. Perhaps a stray comet or asteroid struck an icy moon, tossing its remnants into orbit. Or maybe the orbits of Saturn’s moons somehow shifted, and the resulting gravitational tug-of-war pulled a moon apart. However it happened, two new lines of evidence from Cassini make it clear that the rings were not around in the early days of the solar system 4.5 billion years ago, as scientists had long believed, says Jeff Cuzzi, a ring specialist at NASA’s Ames Research Center in Mountain View, California. “It rules out the primordial ring story,” Cuzzi says. “That’s what it looks like to me.”

At the moment there is no consensus on what might have caused the rings formation so recently.

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MU69 might have a moon

1:51 pm

Worlds without end: Observations of stellar occultations this past summer of 2014 MU69, New Horizons’ Kuiper belt target for a January 1, 2019 fly-by, suggest that the object is not only very elongated or two objects practically touching as they orbit around each other, but it might have a moon orbiting it.

The data that led to these hints at MU69’s nature were gathered over six weeks in June and July, when the team made three attempts to place telescopes in the narrow shadow of MU69 as it passed in front of a star. The most valuable recon came on July 17, when five telescopes deployed by the New Horizons team in Argentina were in the right place at the right time to catch this fleeting shadow — an event known as an occultation – and capture important data on MU69’s size, shape and orbit. That data raised the possibility that MU69 might be two like-sized objects, or what’s known as a binary.

The prospect that MU69 might have a moon arose from data collected during a different occultation on July 10, by NASA’s airborne Stratospheric Observatory for Infrared Astronomy (SOFIA). Focused on MU69’s expected location while flying over the Pacific Ocean, SOFIA detected what appeared to be a very short drop-out in the star’s light. Buie said further analysis of that data, including syncing it with MU69 orbit calculations provided by the European Space Agency’s Gaia mission, opens the possibility that the “blip” SOFIA detected could be another object around MU69. “A binary with a smaller moon might also help explain the shifts we see in the position of MU69 during these various occultations,” Buie added. “It’s all very suggestive, but another step in our work to get a clear picture of MU69 before New Horizons flies by, just over a year from now.”

All of this is somewhat speculative. We really won’t know until New Horizons arrives next year.

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Faults on Mars

9:20 am

Faults on Mars

Cool image time! The Mars Reconnaissance Orbiter (MRO) image on the right, reduced in resolution to post here, captures a distinctive fault line that cuts across some layered deposits. As noted by the MRO science team,

Some of the faults produced a clean break along the layers, displacing and offsetting individual beds (yellow arrow).

Interestingly, the layers continue across the fault and appear stretched out (green arrow). These observations suggest that some of the faulting occurred while the layered deposits were still soft and could undergo deformation, whereas other faults formed later when the layers must have been solidified and produced a clean break.

Meridiani Planum

These layers are located in Meridiani Planum, a relatively flat area on the Martian equator. Opportunity landed on this plain to the southwest of this region, as shown on the geology map to the left. The white cross in the southwest corner indicates Opportunity’s landing site, with Endeavour Crater just to the southeast. The white box in the northwest shows where the faulted layered deposits are located. Based on the scale of the map, this places Opportunity approximately 400 miles away.

What exactly caused these distinct faults remains unknown. The likely cause would be a earthquake, but since Mars does not have plate tectonics like the Earth, earthquakes would have to be caused by other geological processes not yet studied.

To my eye, they look like cracks in a mirror, though this provides no real explanation other than it illustrates how cool the image is.

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Flying through Jupiter’s Great Red Spot

8:40 am

Cool movie time! In conjunction with the release yesterday of data from Juno’s first close fly-over of Jupiter’s Great Red Spot, the science team also released an animation of what it would be like to fly down into the Spot.

You can also download the mp4 file here. It is definitely worth watching. It illustrates forcefully how daunting and challenging it will be for the human race to ever explore the vastness of Jupiter. This simulated plunge only goes into the Great Red Spot a few hundred miles, and barely touches its dynamics.

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Juno’s look at Jupiter’s Great Red Spot

3:10 pm

The Juno science team released its results from the spacecraft’s first close fly over of Jupiter’s Great Red Spot in July 2017.

Jupiter’s Great Red Spot is a giant oval of crimson-colored clouds in Jupiter’s southern hemisphere that race counterclockwise around the oval’s perimeter with wind speeds greater than any storm on Earth. Measuring 10,000 miles (16,000 kilometers) in width as of April 3, 2017, the Great Red Spot is 1.3 times as wide as Earth.

“Juno found that the Great Red Spot’s roots go 50 to 100 times deeper than Earth’s oceans and are warmer at the base than they are at the top,” said Andy Ingersoll, professor of planetary science at Caltech and a Juno co-investigator. “Winds are associated with differences in temperature, and the warmth of the spot’s base explains the ferocious winds we see at the top of the atmosphere.”

The future of the Great Red Spot is still very much up for debate. While the storm has been monitored since 1830, it has possibly existed for more than 350 years. In the 19th century, the Great Red Spot was well over two Earths wide. But in modern times, the Great Red Spot appears to be diminishing in size, as measured by Earth-based telescopes and spacecraft. At the time NASA’s Voyagers 1 and 2 sped by Jupiter on their way to Saturn and beyond, in 1979, the Great Red Spot was twice Earth’s diameter. Today, measurements by Earth-based telescopes indicate the oval that Juno flew over has diminished in width by one-third and height by one-eighth since Voyager times.

The storm’s estimate depth, about 200 miles, seems gigantic, but then we must remember this storm is on a gas giant that is about 88k miles in diameter, about ten times larger than Earth. The relative size of this storm to the size of Jupiter therefore is really not that much different than the relative size of big hurricanes on Earth. At the same time, the realities here are daunting, filled with unknowns, chief of which is the fact that unlike Earth, the Great Red Spot is a storm that is floating high in the atmosphere with no solid surface below it.

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Breakthrough Listen to observe Ourmuamua

10:47 am

Breakthrough Listen, one of billionaire Yuri Milner’s Breakthrough initiatives, is going to do an observation campaign of the interstellar object Ourmuamua using the Green Bank Radio telescope.

It has a highly unusual structure for an asteroid – an elongated cigar shape, hundreds of meters in length but with width and height perhaps only one tenth as long.

Researchers working on long-distance space transportation have previously suggested that a cigar or needle shape is the most likely architecture for an interstellar spacecraft, since this would minimize friction and damage from interstellar gas and dust. While a natural origin is more likely, there is currently no consensus on what that origin might have been, and Breakthrough Listen is well positioned to explore the possibility that ‘Oumuamua could be an artifact.

Listen’s observation campaign will begin on Wednesday, December 13 at 3:00 pm ET. Using the Robert C. Byrd Green Bank Telescope, it will continue to observe ‘Oumuamua across four radio bands, from 1 to 12 GHz. Its first phase of observations will last a total of 10 hours, divided into four “epochs” based on the object’s period of rotation.

If anything, this observation will provide us more information about Ourmuamua itself, which unfortunately is very limited because the object was already on its way out when it was discovered.

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New Horizons successfully does course correction

8:54 am

New Horizons yesterday successfully fired its engines for 2.5 minutes to refine its course and January 1, 2019 fly-by of Kuiper belt object 2014 MU69.

The maneuver both refined the course toward and optimized the flyby arrival time at MU69, by setting closest approach to 12:33 a.m. EST (5:33 UTC) on Jan. 1, 2019. The prime flyby distance is set at 2,175 miles (3,500 kilometers); the timing provides better visibility for DSN’s powerful antennas to reflect radar waves off the surface of MU69 for New Horizons to receive – a difficult experiment that, if it succeeds, will help scientists determine the reflectivity and roughness of MU69’s surface.

The spacecraft will next be put in hibernation on December 21, and stay in that state until June.

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More delays expected for launch of Webb telescope

8:52 am

NASA’s chief scientist admitted during House hearings this week that there will possibly be further delays in the launch of the James Webb Space Telescope, now set for the 2nd quarter of 2019.

“At this moment in time, with the information that I have, I believe it’s achievable,” he said of the current launch window of March to June 2019, which NASA announced in September after delaying the launch from October 2018. However, he said an independent review “is exactly what we should be doing, and frankly I have directed the team to do just that in January.”

That review won’t start until January, he said, because of ongoing tests of unfolding the sunshade of the space telescope. Previous tests, he said, took much longer than anticipated, playing a key factor in the decision to delay the launch. An updated launch date, he said, would likely come in “January or February.”

Such an independent review was proposed earlier in the hearing by another witness, retired aerospace executive Thomas Young. “In my opinion, the launch date and required funding cannot be determined until a new plan is thoroughly developed and verified by independent review,” he said.

While it does make perfect sense to make sure everything is really really really ready before launch, that this telescope is already 8 years behind schedule and yet might still need more delays suggests that the whole project was managed badly, from start to finish.

The hearing also dealt with the cost increases NASA is experiencing for WFIRST. As is usual, it sounds like NASA’s buy-in approach there has worked, and that Congress will fork up the extra cash to keep that project alive, until it experiences further delays and more cost increases, when Congress will fork up even more money. Then, wash and repeat. The WFIRST budget is already up from about $3.5 billion to more than $4 billion. I predict before it is done it will have cost around $8-$10 billion, and not launch until the late 2020s, at the earliest.

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More data tampering to prove global warming, this time with tidal gauges

1:16 pm

An analysis of the adjustments made to three Indian Ocean tidal gauges suggests that this was not to correct errors but to tamper with the data to prove global warming and an accelerating rise in sea level because of it.

The authors do not mince their words. They refer to these adjustments as “highly questionable” and “suspicious.”

That’s because they can find no plausible scientific explanation for the adjustments.

The last sentence is the bottom line. At no time are such adjustments ever justified with any credible or plausible scientific evidence. They are always “arbitrary,” a word used repeatedly in the paper. And as the paper’s author’s also note,

It is always highly questionable to shift data collected in the far past without any proven new supporting material.

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Calculating the number of alien space artifacts in our solar system

10:53 am

Link here. The author attempts to make a back of the envelope calculation of the number of abandoned alien interstellar spacecraft in the Milky Way (like our Voyager and Pioneer spacecraft), and from this calculate the number that might actually be drifting through the solar system. His conclusions?

Wondering if there’s any alien goodies in our solar system?

Well, the distance inner edge of the Oort cloud is estimated to be 4,000 A.U. This would make the volume of the solar system = 201 million cubic A.U.s, and the chance of an alien artifact adrift in our solar system (other than our own) is less than 1 in a 1,000,000. Using the outer edge distance for the Oort cloud at 50,000 AU = gives the volume of the solar system at 31.4 billion, with a slightly better than 1-in-45 chance.

But the nearest star system, Alpha Centauri is 4.4 light years distant, which equals a sphere 243 cubic light years in volume, with lots of elbow room for alien space junk!

The author also admits that these calculations depend on many assumptions, and should not be taken very seriously. Nonetheless, they are intriguing, and fun to consider.

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Physicists look for new alternatives to explain dark matter

6:55 pm

The uncertainty of science: Having failed to detect WIMPs, their primary dark matter suspect, physicists are now looking at new and different candidates that might explain dark matter, and the new leading candidate is something called SIMPs.

The intensive, worldwide search for dark matter, the missing mass in the universe, has so far failed to find an abundance of dark, massive stars or scads of strange new weakly interacting particles (WIMPs), but a new candidate is slowly gaining followers and observational support.

Called SIMPs – strongly interacting massive particles – they were proposed three years ago by UC Berkeley theoretical physicist Hitoshi Murayama, a professor of physics and director of the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) in Japan, and former UC Berkeley postdoc Yonit Hochberg, now at Hebrew University in Israel.

Murayama says that recent observations of a nearby galactic pile-up could be evidence for the existence of SIMPs, and he anticipates that future particle physics experiments will discover one of them.

We shall see. The mystery remains, that we do not understand why most galaxies do not fly apart because their outer stars simply move too fast. Since all searches for ordinary matter have come up well short, dark matter remains the simplest explanation, though it still reminds me the theories of ether that once dominated physics, and never existed.

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The Sun goes quiet! Sunspot update for November 2017

11:51 am

The past month was the most inactive month for sunspots since the middle of 2009, when the last solar minimum was just ending and the Sun was beginning its ramp up to solar maximum.

NOAA on Sunday posted its monthly update of the solar cycle, covering sunspot activity for November. As I have done every month since 2010, I have posted that graph below, with annotations.

November 2017 Solar Cycle graph

The graph above has been modified to show the predictions of the solar science community. The green curves show the community’s two original predictions from April 2007, with half the scientists predicting a very strong maximum and half predicting a weak one. The red curve is their revised May 2009 prediction.

I have also added a straight yellow line near the bottom of the graph, indicating how the lack of activity this past month corresponds with the lack of activity in the summer of 2009, just when that unusually long and deep solar minimum was beginning to end.

November 2017 sunspot record

To get an idea how few sunspots were seen in November, the graph on the right, produced by SILSO (Sunspot Index and Long-term Solar Observations) on December 1, shows only 10 days during the entire month when any sunspots were active on the Sun’s visible hemisphere. And even those sunspot were few and weak, resulting in tiny sunspot numbers total.

Nor is December looking any different, with no sunspots recorded so far, four days into the month.

The plunge to solar minimum continues to appear to be happening faster than normal. At this pace, solar minimum will arrive in early 2018, making this one of the shortest solar cycles on record. That in itself would be unprecedented, as short cycles in the past have always accompanied very active solar maximums, not weak maximums like the maximum we have just seen.

I still expect the ramp down to solar minimum to slow down and stretch out to 2019, as would be more normal, but I also would not bet any money on this expectation, at this point.

The big question remains: Will the solar cycle continue as normal after this upcoming solar minimum, or will we instead see our first grand minimum since the Maunder Minimum in the 1600s, a period lasting for about a century with no obvious sunspots that also corresponded to the Little Ice Age?

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The fly-by anomaly returns with Juno

9:48 pm

The uncertainty of science: An orbital discrepancy between where engineers predict where Juno should be and where it actually is suggests it represents the recurrence of an anomaly that has been seen with numerous past planetary spacecraft.

During the 1970s when the Pioneer 10 and 11 probes were launched, visiting Jupiter and Saturn before heading off towards the edge of the Solar System, these probes both experienced something strange as they passed between 20 to 70 AU (Uranus to the Kuiper Belt) from the Sun.

Basically, the probes were both 386,000 km (240,000 mi) farther from where existing models predicted they would be. This came to be known as the “Pioneer anomaly“, which became common lore within the space physics community. While the Pioneer anomaly was resolved, the same phenomena has occurred many times since then with subsequent missions.

…Another mystery is that while in some cases the anomaly was clear, in others it was on the threshold of detectability or simply absent – as was the case with Juno‘s flyby of Earth in October of 2013. The absence of any convincing explanation has led to a number of explanations, ranging from the influence or dark matter and tidal effects to extensions of General Relativity and the existence of new physics.

However, none of these have produced a substantive explanation that could account for flyby anomalies.

The article describes in detail an effort to pin down the extent of Juno’s orbital anomaly, and to use that information to develop a model that would explain the phenomenon. Not surprisingly, they have not really come up with a comprehensive explanation. To me, the variability of the phenomenon suggests that it isn’t real, that it is either an unmeasured instrument effect or an ordinary component of solar system travel and orbital mechanics that programmers have not yet pinned down. For example, the gravitational effect of every planet and rock in the solar system will influence the path of a spacecraft, though with most that influence will be very small. It would not surprise me if this anomaly is simply the consequence of missing some of this influence.

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Voyager 1 fires thrusters not used in 37 years

3:30 pm

Because Voyager 1’s primary attitude thrusters are beginning to show wear (after forty years in space), engineers decided to experiment using a different set of thrusters not used since the spacecraft flew past Saturn in 1980, and found that they worked!

In the early days of the mission, Voyager 1 flew by Jupiter, Saturn, and important moons of each. To accurately fly by and point the spacecraft’s instruments at a smorgasbord of targets, engineers used “trajectory correction maneuver,” or TCM, thrusters that are identical in size and functionality to the attitude control thrusters, and are located on the back side of the spacecraft. But because Voyager 1’s last planetary encounter was Saturn, the Voyager team hadn’t needed to use the TCM thrusters since November 8, 1980. Back then, the TCM thrusters were used in a more continuous firing mode; they had never been used in the brief bursts necessary to orient the spacecraft.

…On Tuesday, Nov. 28, 2017, Voyager engineers fired up the four TCM thrusters for the first time in 37 years and tested their ability to orient the spacecraft using 10-millisecond pulses. The team waited eagerly as the test results traveled through space, taking 19 hours and 35 minutes to reach an antenna in Goldstone, California, that is part of NASA’s Deep Space Network.

Lo and behold, on Wednesday, Nov. 29, they learned the TCM thrusters worked perfectly — and just as well as the attitude control thrusters.

They figure these back-up thrusters will allow them to extend the mission by two or three years. The test also went so well that they now plan to do the same test on Voyager 2, which has still not entered interstellar space.

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Baby stars at center of galaxy

2:40 pm

New observations of the region surrounding Sagittarius A* (Sgr A*), the super-massive black hole at the center of the Milky Way, has confirmed earlier research by finding what appears to be eleven newly formed baby stars.

Prior observations of the region surrounding Sgr A* by Zadeh and his team had revealed multiple massive infant stars but the finding was not conclusive. These objects, known as proplyds, are common features in more placid star-forming regions, like the Orion Nebula. The new measurements provide more conclusive evidence for young star formation activity. Though the galactic center is a challenging environment for star formation, it is possible for particularly dense cores of hydrogen gas to cross the necessary threshold and forge new stars.

The new ALMA observations, however, revealed something even more remarkable, signs that 11 low-mass protostars are forming within one parsec – a scant three light-years – of the galaxy’s central black hole. Zadeh and his team used ALMA to confirm that the masses and momentum transfer rates – the ability of the protostar jets to plow through surrounding interstellar material – are consistent with young protostars found throughout the disk of our galaxy. “This discovery provides evidence that star formation is taking place within clouds surprisingly close to Sagittarius A*,” said Al Wootten with the National Radio Astronomy Observatory in Charlottesville, Virginia, and co-author on the paper.

They have several theories on how new stars could coalesce in such a violent and turbulent region, but none appears that convincing. Essentially, this is a mystery that does not yet have an answer. It does tell us however that star formation can occur almost anywhere.

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The organic dust of Comet 67P/C-G

11:36 am

A study of the dust released by Comet 67P/C-G and captured by Rosetta shows that carbon molecules appear to comprise the comet’s largest component, and that this material is found in the form of very large macromolecules.

As the study shows, organic molecules are among those ingredients at the top of the list. These account for about 45 percent of the weight of the solid cometary material. “Rosetta’s comet thus belongs to the most carbon-rich bodies we know in the solar system,” says MPS scientist and COSIMA team member Dr. Oliver Stenzel. The other part of the total weight, about 55 percent, is provided by mineral substances, mainly silicates. It is striking that they are almost exclusively non-hydrated minerals i.e. missing water compounds. “Of course, Rosetta’s comet contains water like any other comet, too,” says Hilchenbach. “But because comets have spent most of their time at the icy rim of the solar system, it has almost always been frozen and could not react with the minerals.” The researchers therefore regard the lack of hydrated minerals in the comet’s dust as an indication that 67P contains very pristine material.

…The current findings also touch on our ideas of how life on Earth came about. In a previous publication, the COSIMA team was able to show that the carbon found in Rosetta’s comet is mainly in the form of large, organic macromolecules. Together with the current study, it becomes clear that these compounds make up a large part of the cometary material. Thus, if comets indeed supplied the early Earth with organic matter, as many researchers assume, it would probably have been mainly in the form of such macromolecules.

Organic here does not mean life, but is instead used as chemists use it, to mean the molecule includes the element carbon. The results do suggest however that the early solar system had a lot of carbon available, and that much of it was in a relatively pure form available to interact with other elements.

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Chinese space probe detects possible dark matter signal

8:56 am

The uncertainty of science: A Chinese space probe designed to measure cosmic rays has detected a pattern that could be evidence of the existence of dark matter.

Researchers launched the spacecraft from the Jiuquan Satellite Launch Center in the Gobi Desert, about 1600 kilometers west of Beijing, in December 2015. Its primary instrument—a stack of thin, crisscrossed detector strips—is tuned to observe the incoming direction, energy, and electric charge of the particles that make up cosmic rays, particularly electrons and positrons, the antimatter counterparts of electrons. Cosmic rays emanate from conventional astrophysical objects, like exploding supernovae in the galaxy. But if dark matter consists of WIMPs, these would occasionally annihilate each other and create electron-positron pairs, which might be detected as an excess over the expected abundance of particles from conventional objects.

In its first 530 days of scientific observations, DAMPE detected 1.5 million cosmic ray electrons and positrons above a certain energy threshold. When researchers plot of the number of particles against their energy, they’d expect to see a smooth curve. But previous experiments have hinted at an anomalous break in the curve. Now, DAMPE has confirmed that deviation. “It may be evidence of dark matter,” but the break in the curve “may be from some other cosmic ray source,” says astrophysicist Chang Jin, who leads the collaboration at the Chinese Academy of Science’s (CAS’s) Purple Mountain Observatory (PMO) in Nanjing. [emphasis mine]

I must emphasize the large uncertainty here. They have not detected dark matter. Not even close. What they have detected is a pattern in how the spacecraft is detecting cosmic rays that was predicted by the existence of dark matter. That pattern however could have other causes, and the consistent failure of other efforts to directly find dark matter strengthens the possibility that this break is caused by those other causes.

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“Yeti” DNA found to come from bears and dogs

8:59 am

Scientists analyzing DNA samples said to come from either the legendary yeti in the Himalayas or sasquatch in North America have found that all come from known ordinary animals, mostly bears.

Of the nine “yeti” samples, eight turned out to be from bears native to the area, the researchers report today in the Proceedings of the Royal Society B. The other sample came from a dog. Similar studies of hair samples supposedly related to North America’s big hairy hominid, the sasquatch (aka Bigfoot), have revealed that those fibers came from bears, horses, dogs, and a variety of other creatures—even a human.

Debunking aside, the new study also yielded lots of scientifically useful info, Lindqvist says. The analyses generated the first full mitochondrial genomes for the Himalayan brown bear (Ursus arctos isabellinus) and the Himalayan black bear (Ursus thibetanus laniger), for example. That could help scientists figure out how genetically different these rare subspecies are from more common species, as well as the last time these groups shared maternal ancestors in the past.

While we must always recognize the uncertainties of science, we must also recognize when it provides us clarity. This is an example of the latter.

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Wind eating away the Martian terrain

9:44 am

Yardangs on Mars

Cool image time! The Mars Reconnaissance Orbiter (MRO) image on the right, cropped and reduced in resolution to post here, shows the transition zone between the lower flat plain to the north and the higher but rougher region to the south. What makes it interesting is the north-south aligned mesas. These are yardangs, a geological feature that actually acts like a weather vane.

Yardangs are composed of sand grains that have clumped together and have become more resistant to erosion than their surrounding materials.

As the winds of Mars blow and erode away at the landscape, the more cohesive rock is left behind as a standing feature. (This Context Camera image shows several examples of yardangs that overlie the darker iron-rich material that makes up the lava plains in the southern portion of Elysium Planitia.) Resistant as they may be, the yardangs are not permanent, and will eventually be eroded away by the persistence of the Martian winds.

For scientists observing the Red Planet, yardangs serve as a useful indicator of regional prevailing wind direction. The sandy structures are slowly eroded down and carved into elongated shapes that point in the downwind direction, like giant weathervanes. In this instance, the yardangs are all aligned, pointing towards north-northwest. This shows that the winds in this area generally gust in that direction.

Crater splash

The wind comes from the southeast and blows to the northwest, and is slowly wearing down the southern rougher terrain. Why some of these yardangs are surrounded by dark material remains a mystery, as noted I noted in a previous post.

Meanwhile, the northern plain is not as boring as it seems. Only a short distance to the north is an unusual crater, cropped from the full image to show here on the right. To my eye, when this impact occurred it literally caused a splashlike feature of compressed and more resistant material. Over time, the prevailing wind has eroded away the surrounding less resistant regolith to better reveal that splash, leaving behind a mesa with a crater in its center.

Why the impact created this splash tells us something about the density and make-up of the plain. It suggests to me a surface that was once muddy and soft that over time has hardened like sandstone.

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Worms on Mars!

9:09 am

Scientists growing plants on Earth using a simulated Martian soil have found that earthworms like it.

These slimy invertebrates play a key role in making Earth soil healthy by digesting dead organic matter and excreting a potent fertilizer that helps release nutrients like nitrogen and phosphorus. Their constant burrowing also helps lighten up the soil, allowing air and water to seep through better.

That’s an important improvement for the simulated Mars soil, which water struggled to soak through in previous tests. Altogether, the tests showed that the combination of worms and pig slurry helped the plants grow in Martin soil, and the worms not only thrived but reproduced. “Clearly the manure stimulated growth, especially in the Mars soil simulant, and we saw that the worms were active,” says Wamelink. “However, the best surprise came at the end of the experiment when we found two young worms in the Mars soil simulant.”

Obviously, we do not know yet how the worms would respond to the lower Martian gravity, but it sure would be a significant experiment to see them reproduce there.

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Russia astronauts have found bacteria living on the outside of ISS

8:42 am

Russia astronauts have found bacteria that was not intentionally brought into space living on the outside of ISS.

They are being studied on Earth but most likely they don’t pose any sort of danger, Russian cosmonaut Anton Shkaplerov told TASS on Monday. According to him, during spacewalks from the International Space Station under the Russian program, the cosmonauts took samples with cotton swabs from the station’s external surface. In particular, they took probes from places where the accumulation of fuel wastes were discharged during the engines’ operation or at places where the station’s surface is more obscure. After that, the samples were sent back to Earth.

“And now it turns out that somehow these swabs reveal bacteria that were absent during the launch of the ISS module. That is, they have come from outer space and settled along the external surface.”

I suspect it is a bit of hyperbole to say the bacteria came from outer space. It more likely came from either the station itself, or later spacecraft docking with the station. At the same time, the article is vague about what has been discovered. For example, it says nothing about the bacteria itself.

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