Tag: science

Early Milky Way collision uncovered by Gaia

12:21 pm

Data from the space telescope Gaia has revealed a Milky Way merger event that occurred about 10 billion years ago.

Using the first 22 months of observations, a team of astronomers led by Amina Helmi, University of Groningen, The Netherlands, looked at seven million stars – those for which the full 3D positions and velocities are available – and found that some 30,000 of them were part of an ‘odd collection’ moving through the Milky Way. The observed stars in particular are currently passing by our solar neighbourhood.

We are so deeply embedded in this collection that its stars surround us almost completely, and so can be seen across most of the sky.

Even though they are interspersed with other stars, the stars in the collection stood out in the Gaia data because they all move along elongated trajectories in the opposite direction to the majority of the Galaxy’s other hundred billion stars, including the Sun. They also stood out in the so-called Hertzprung-Russell diagram – which is used to compare the colour and brightness of stars – indicating that they belong to a clearly distinct stellar population.

The sheer number of odd-moving stars involved intrigued Amina and her colleagues, who suspected they might have something to do with the Milky Way’s formation history and set to work to understand their origins. In the past, Amina and her research group had used computer simulations to study what happens to stars when two large galaxies merge. When she compared those to the Gaia data, the simulated results matched the observations. “The collection of stars we found with Gaia has all the properties of what you would expect from the debris of a galactic merger,” says Amina, lead author of the paper published today in Nature.

At the time, the two galaxies were both probably about the same size, approximately equivalent to the Magellanic Clouds.

Must I mention that there is some uncertainty here? The data is good, and the conclusions seem quite reasonable. At the same time, the data is still somewhat thin. We need a lot more Gaia-type telescopes mapping out the motions and positions of all the stars of the Milky Way in far more detail before the uncertainties here will shrink.

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Timelapse movie of Supernova 1987A’s evolution from 1992 to 2017

9:42 am

Cool movie time! An astronomy graduate student in Toronto has created a movie showing the steady evolution of the shock wave from Supernova 1987A, the first supernova visible to the naked eye since the discovery of the telescope, during the past twenty-five years.

Yvette Cendes, a graduate student with the University of Toronto and the Leiden Observatory, has created a time-lapse showing the aftermath of the supernova over a 25-year period, from 1992 to 2017. The images show the shockwave expanding outward and slamming into debris that ringed the original star before its demise.

In an accompanying paper, published in the Astrophysical Journal on October 31st, Cendes and her colleagues add to the evidence that the expanding remnant is shaped—not like a ring like those of Saturn’s—but like a donut, a form known as a torus. They also confirm that the shockwave has now picked up some one thousand kilometres per second in speed. The acceleration has occurred because the expanding torus has punched through the ring of debris.

The animation, which I have embedded below the fold, uses images produced by an array radio telescopes in Australia.
» Read more

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Oblique view of Hayabusa-2’s most recent landing rehearsal

9:28 am

Cool movie time! The Hayabusa-2 science team has released a small movie of images taken by a side-mounted camera of the spacecraft’s most recent landing rehearsal, showing the spacecraft ascend from its closest approach from an oblique angle.

I have embedded the movie from these images below the fold. As they note,

Images taken with the small monitor camera (CAM-H) during the Touchdown 1 Rehearsal 3 operation (TD1-R3). One image was captured every second from immediately after the spacecraft began to ascend (altitude 21m) on October 25, 2018 at 11:47 JST. The spacecraft was rising at about 52cm/s.

It appears the closest image was taken from about 21 meters away, about 65 feet, and gives a sense of scale. It also reveals once again how difficult that landing in January is going to be. Though this location is thought to be the smoothest spot on Ryugu, it is still littered with rocks that could cause problems.
» Read more

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NASA decides to continue to ping Opportunity

9:10 am

NASA has decided to continue through January its effort to both listen and send signals to Opportunity in the hope of bringing it to life.

The 45-day deadline passed late last week. But NASA will continue active listening — a strategy that involves both sending commands to Opportunity and listening for any peeps the six-wheeled robot may make — for several more months at least, agency officials announced yesterday. “After a review of the progress of the listening campaign, NASA will continue its current strategy for attempting to make contact with the Opportunity rover for the foreseeable future,” NASA officials wrote in a mission update yesterday. “Winds could increase in the next few months at Opportunity’s location on Mars, resulting in dust being blown off the rover’s solar panels,” they added. “The agency will reassess the situation in the January 2019 time frame.”

This is exactly what the planetary scientists wanted. Their hope is that, with the beginning of dust devil season in November, the chances will then increase for removing the dust that likely covers the rover’s solar panels. It is thought that the rover has a better shot at coming back to life during this time period.

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NASA officially retires Kepler

12:42 pm

NASA today officially retired Kepler after nine years of operations.

After nine years in deep space collecting data that indicate our sky to be filled with billions of hidden planets – more planets even than stars – NASA’s Kepler space telescope has run out of fuel needed for further science operations. NASA has decided to retire the spacecraft within its current, safe orbit, away from Earth. Kepler leaves a legacy of more than 2,600 planet discoveries from outside our solar system, many of which could be promising places for life.

Exoplanet hunting however does not end here. Unlike Hubble, astronomers and NASA planned ahead for Kepler’s demise, and this year launched TESS to continue its work, in an even more sophisticated manner.

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The steep slumping wall of a Martian volcano caldera

10:19 am

Caldera wall

Cool image time. The Mars Reconnaissance Orbiter science team today released a nice captioned image of the steep wall of the caldera of Ascraeus Mons, the northernmost of the three giant volcanoes that lie to the east of Olympus Mons, the biggest volcano of all. The image on the right, reduced and cropped, shows that steep wall, with full image available by clicking on it. The caption from the release focuses on the fluted upper parts of the wall.

We can see chutes carved into the soft dust that has built up on the slope, with some similarities to gully landforms elsewhere on the planet.

More revealing to me is how this image reveals the slumping that is slowing eroding the caldera’s walls while also making that caldera larger. First, the plateau above the cliff shows multiple small cliffs and pit chains, all more or less parallel to the wall. This suggests that the plateau is over time breaking apart and falling into that caldera. Think of it as an avalanche in slow motion, with the upper plateau separating into chunks as sections slowly tilt down toward eventual collapse. As these chunks separate, they cause cracks to form in that plateau, and hence the parallel cliffs and strings of pits.

On the floor of the caldera we can see evidence of past chunks that did fall, piled up in a series terraces at the base of the wall. These are covered with the soft dust that dominates Martian geology. That soft dust also apparently comprises much of the wall’s materials, and almost acts like a liquid as it periodically flows down the wall, producing the chutes at the top of the wall.

The weak Martian gravity here is an important factor that we on Earth have difficulty understanding. It allows for a much steeper terrain, that also allows structurally weaker materials to hold together that would be impossible on Earth.This image gives a taste of this alien geology, on a large scale.

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Parker sets new records in its flight to the Sun

9:19 am

The Parker Solar Probe has set two new space records, first for making the closest approach to the Sun as well as becoming the fastest spacecraft ever.

The spacecraft passed the current record of 26.55 million miles from the Sun’s surface on Oct. 29, 2018, at about 1:04 p.m. EDT, as calculated by the Parker Solar Probe team. The previous record for closest solar approach was set by the German-American Helios 2 spacecraft in April 1976. As the Parker Solar Probe mission progresses, the spacecraft will repeatedly break its own records, with a final close approach of 3.83 million miles from the Sun’s surface expected in 2024.

“It’s been just 78 days since Parker Solar Probe launched, and we’ve now come closer to our star than any other spacecraft in history,” said Project Manager Andy Driesman, from the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. “It’s a proud moment for the team, though we remain focused on our first solar encounter, which begins on Oct. 31.”

Parker Solar Probe is also expected to break the record for fastest spacecraft traveling relative to the Sun on Oct. 29 at about 10:54 p.m. EDT. The current record for heliocentric speed is 153,454 miles per hour, set by Helios 2 in April 1976.

We ain’t seen nothin’ yet. This is only the first orbit. With each later orbit the spacecraft will zip past the Sun faster, and closer.

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IAU once again sticks it to an American scientist, devaluing Edwin Hubble

9:00 am

In what is already seen by many scientists as an inappropriate action, the International Astronomical Union (IAU) this week voted to change the name of Hubble’s Law to the Hubble-Lemaître Law.

Hubble’s Law, a cornerstone of cosmology that describes the expanding universe, should now be called the Hubble-Lemaître Law, following a vote by the members of the International Astronomical Union (IAU), the same organization that revoked Pluto’s status as a planet. The change is designed to redress the historical neglect of Georges Lemaître, a Belgian astronomer and priest who in 1927 discovered the expanding universe—which also suggests a big bang. Lemaître published his ideas 2 years before U.S. astronomer Edwin Hubble described his observations that galaxies farther from the Milky Way recede faster.

There are so many things about this that are wrong it is hard to keep count. First, the IAU was never given the right to change the name of a scientific concept. It’s original job was merely to systemize the naming of astronomical objects, and that alone.

Second, it appears to be based on a misunderstanding of basic science.

The resolution has also come under fire for confusing two different issues: the expansion of the universe and the distance-velocity relation for galaxies, which is also known as the Hubble constant. Hubble never claimed to have discovered cosmic expansion, but did do much of observing work to nail down how fast the universe was expanding. “If the law is about the empirical relationship, it should be Hubble’s Law,” Kragh says. “If it is about cosmic expansion, it should be Lemaître’s Law.”

Third, it relies on bad history.

The text of the IAU resolution, circulated to members ahead of the vote, asserts that Hubble and Lemaître met in 1928, at an IAU general assembly in Leiden, the Netherlands—between the publication of their two papers—and “exchanged views” about the blockbuster theory. Kragh says that meeting “almost certainly didn’t take place” and that IAU’s statement “has no foundation in documented history.”

There are other problems, including the method by which the IAU conducted its vote. The bottom line is that this organization has no business sticking its nose into this issue, and it illustrates again, as happened when it tried to push a bad definition of “planets” on the planetary community in order to devalue the discovery of Pluto by an American, that there is a strong anti-American streak within it.

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Scientists calculate Mars methane release

8:56 am

A new model describing how warmer weather could cause the seasonal spikes of methane on Mars matches the data from Curiosity in Gale Crater.

Moores and his colleagues analysed how methane might seep upwards through cracks and fissures in the Martian soil until it enters the atmosphere. Warming the soil could allow the gas to leak into the air, their calculations show. Seasons on Mars are complex, especially at Curiosity’s location so close to the planet’s equator. But the highest methane levels do appear just after the warmest time of the year, suggesting that heat spreading downward allows more of the gas to be released.

The amount of gas that the scientists estimate is entering the atmosphere is a good match for the measurements Curiosity has made at Gale crater, Moores told the American Astronomical Society’s Division for Planetary Sciences meeting in Knoxville, Tennessee. The methane’s ultimate source is still a mystery. But the work could help to explain the gas’s seasonal ebb and flow, he said. [emphasis mine]

The highlighted sentence is the most important. All they have done is found that they can model the pattern of seasonal release. They still have no idea whether the methane comes from a geological or biological source, which is of course the real question.

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Fast radio bursts not detected at certain radio wavelengths

8:47 am

In observations by two different radio telescopes operating at different radio wavelengths but looking at the same part of the sky, astronomers have found that an observed fast radio burst was not detected by one of those telescopes.

The Curtin University-led Murchison Widefield Array (MWA) and CSIRO’s Australian SKA Pathfinder (ASKAP) telescopes were searching the sky for fast radio bursts, which are exceptionally bright flashes of energy coming from deep space. These extreme events last for only a millisecond but are so bright that many astronomers initially dismissed the first recorded fast radio burst as an observational error.

In research published in the Astrophysical Journal Letters, astronomers describe how ASKAP detected several extremely bright fast radio bursts, but the MWA—which scans the sky at lower frequencies—did not see anything, even though it was pointed at the same area of sky at the same time.

Lead author Dr Marcin Sokolowski, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said the fact that the fast radio bursts were not observed at lower frequencies was highly significant. “When ASKAP sees these extremely bright events and the MWA doesn’t, that tells us something really unexpected is going on; either fast radio burst sources don’t emit at low frequencies, or the signals are blocked on their way to Earth,” Dr Sokolowski said.

If blocked at these lower frequencies, this tells theorists something about the environment where the burst occurred. If instead the burst does not emit in those lower frequencies, it tells them something about the burst itself.

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Number of candidate exo-Earths reduced by Gaia data

8:32 am

Worlds without end: The number of candidate exo-Earths identified by Kepler has now been reduced based on data from Europe’s Gaia telescope.

To date, NASA’s prolific Kepler space telescope has discovered about 30 roughly Earth-size exoplanets in their host stars’ “habitable zone” — the range of orbital distances at which liquid water can likely exist on a world’s surface.

Or so researchers had thought. New observations by the European Space Agency’s (ESA) Gaia spacecraft suggest that the actual number is probably significantly smaller — perhaps between two and 12, NASA officials said today.

Gaia launched in December of 2013 to create an ultraprecise 3D map of the Milky Way. So far, this map includes position information for about 1.7 billion stars and distance data for about 1.3 billion stars, according to NASA officials. Gaia’s observations suggest that some of the Kepler host stars are brighter and bigger than previously believed, the officials added. Planets orbiting such stars are therefore likely larger and hotter than previously thought.

Being hotter and larger, the habitable zone for these stars shifts outward, placing the exoEarth’s outside the habitable zone.

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Hubble resumes science operations

8:27 am

After three weeks of successful trouble-shooting of a backup gyroscope scientists have now returned the Hubble Space Telescope to full science operations.

Everyone should understand that this situation is now very temporary. Hubble no longer has any backup gyroscopes. If another fails, they will have to go to a one-gyroscope mode, holding the second working gyroscope back as a back-up, in order to extend the telescope’s life as much as possilbe. In that mode the telescope can operate for a significant period, but will have limited capabilities.

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Hayabusa-2’s highest resolution image so far

10:11 am

Ryugu up close

The Hayabusa-2 science team has released the highest resolution image taken by the spacecraft so far. The image on the right, reduced to post here, is that image. Click on it to see the full resolution version.

The image resolution is about 4.6mm/pixel. This is the highest resolution image that Hayabusa2 has taken so far and even small rocks with a diameter of 2 – 3cm are clearly visible. The maximum resolution of AMICA –the camera at the time of the first Hayabusa mission— was 6 mm/pixel, so even its resolution has now been exceeded. As the image captured of the asteroid surface from the spacecraft, it will be one of the highest resolution to be taken of Ryugu (MINERVA-II1 and MASCOT which landed on the surface, have captured even higher resolution images).

A feature from the image is the lack of regolith (sandy substance). This was suspected to be true from the images obtained so far, but it is more clearly seen in this high resolution photograph. There is also a collection of pebbles with different colors, which may be evidence that the surface material of Ryugu is mixed.

This was taken during the second landing rehearsal about two weeks ago. The image clearly shows the rubble pile that is Ryugu, lacking anything but cemented rocks. It also illustrates the landing problem faced by Hayabusa-2’s engineers. They need a flat smooth area to land, and they have not really found one that fits their needs.

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Intriguing water-ice cloud on Mars

9:41 am

Water-ice cloud over Arsia Mons

An extended water-ice cloud has formed recently on the downwind side of the large Martian volcano Arsia Mons. The image above, cropped to post here, was taken by Europe’s Mars Express orbiter, and shows the cloud extending westward from the volcano.

In spite of its location, this atmospheric feature is not linked to volcanic activity but is rather a water ice cloud driven by the influence of the volcano’s leeward slope on the air flow – something that scientists call an orographic or lee cloud – and a regular phenomenon in this region.

The cloud can be seen in this view taken on 10 October by the Visual Monitoring Camera (VMC) on Mars Express – which has imaged it hundreds of times over the past few weeks – as the white, elongated feature extending 1500 km westward of Arsia Mons. As a comparison, the cone-shaped volcano has a diameter of about 250 km.

… Mars just experienced its northern hemisphere winter solstice on 16 October. In the months leading up to the solstice, most cloud activity disappears over big volcanoes like Arsia Mons; its summit is covered with clouds throughout the rest of the martian year.

However, a seasonally recurrent water ice cloud, like the one shown in this image, is known to form along the southwest flank of this volcano – it was previously observed by Mars Express and other missions in 2009, 2012 and 2015.

What the article does not mention about these seasonal water ice clouds is that they are thought to be related to the evidence of past glaciers on the volcano’s western slopes. Some scientists believe that significant underground ice, left over from those glaciers, is what causes the clouds.

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Astronomers confirm Earth has satellite dust clouds

9:05 am

Astronomers have confirmed the existence of two satellite dust clouds at the Earth’s L4 and L5 Lagrange points 250 thousand miles away, first spotted back in the 1960s.

The images they obtained show polarised light reflected from dust, extending well outside the field of view of the camera lens. The observed pattern matches predictions made by the same group of researchers in an earlier paper and is consistent with the earliest observations of the Kordylewski clouds six decades ago. Horváth’s group were able to rule out optical artefacts and other effects, meaning that the presence of the dust cloud is confirmed.

Since these locations are potential space station locations, determining the existence and nature of these dust clouds is important.

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Changes on the slopes of Olympus Mons?

12:15 pm

Dark splotches on slopes of Olympus Mons

Cool image time! In reviewing the many images from the October image release from the high resolution camera on Mars Reconnaissance Orbiter (MRO), I came across two images, here and here, labeled “Change Detection in Olympus Maculae.” The image on the right is a cropped and reduced section of the first image, centered on the area of most interest. If you click on the image you can see the full photograph.

I did some research to see if I could find the changes indicated by this title. The location is an area on the outer western slopes of Olympus Mons, the largest volcano in the solar system. I found that MRO has taken images of this location twice before, in 2007, in 2009. I spent about fifteen minutes trying to find something that had changed, but was unable to locate anything, other than what look like a few wind-blown streaks probably caused by dust devils. I suspect I do not know what to look for.

Maybe my readers can spend some time and find these changes. If you do, please let us know in a comment.

Nonetheless, these two images revealed an area on the slopes of Olympus Mons that is most intriguing. It appears that there is a whole string of these dark splotches in this area, all of which have been carefully imaged by MRO several times. These splotches, along with the image titles, suggest that this might be area where there is activity from below that is causing the surface to darken. Could it be volcanic? Not likely. More likely is that there is underground frozen water located here, and like the spiders at the poles, this ice periodically pushes up as it sublimates to burst out as gas, and in the process darkens the surface.

If this guess on my part is correct, it suggests that this is an area in the mid-latitudes of Mars where water might be reasonably accessible. For future settlers this would be a significant discovery. And if my guess is wrong no matter. The features are puzzling, which explains why the scientists are aiming MRO at them repeatedly.

If I was to writing my science fiction novel Pioneer today, this is where I would have placed the discovery of the body of the Sanford Addiono, the astronaut who had disappeared on an asteroid near the orbit of Jupiter forty-six years previously. As the press release for the book’s release noted,

How Addiono had gotten to Mars from a distant lost asteroid–without a spaceship–was baffling.

That riddle was magnified by what Addiono had brought back with him. Among his effects was a six-fingered robot hand that had clearly been made by some alien civilization, along with a recorder and memo book describing what Addiono had seen.

What better place to put the start of this mystery but here, on a dark splotch on the slopes of Olympus Mons that also indicates its own geological mystery, a place some underground activity might be reshaping the surface of Mars.

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More successful image downloads for Curiosity

11:24 am

It increasingly looks like the computer download issues on the Mars rover Curiosity are being solved. For the first time in more than five weeks engineers were able to download numerous images from both of the rovers hazard avoidance cameras as well as both of its navigation cameras. More importantly, for the first time in five weeks they were able to do this two days in a row.

The Curiosity science team has as yet released no press update, but it appears that they are carefully testing the computer to make sure it is functioning properly. This computer was the rover’s original primary computer, but when it had problems several months after landing they had switched to the back-up computer. When that back-up computer had problems sending data back to Earth in September they decided to switch back to the original computer, which had been thought fixed.

Because of the original issues with the primary computer I suspect they are simply proceeding very slowly, so as not to have something fail in a manner that will not be recoverable. First they used it two weeks ago to upload a handful of small images from the hazard avoidance and navigation cameras. Then, after a week of analysis they uploaded a few more images from these cameras.

Then, after another week of analysis, they uploaded a full complement of images from all four cameras, and they did it two days in a row, suggesting that they are increasingly confident that the computer is operating correctly.

I expect a press release updating us on the specifics any time now.

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Hayabusa-2 completes third Ryugu touchdown rehearsal

9:34 am

Ryugu up close

Hayabusa-2 today completed its third Ryugu touchdown rehearsal.

According to their operation schedule, they were planning to descent to about 20 meters of the surface, about 65 feet. The image on the right is the closest image taken during the rehearsal. You can see the shadow of Hayabusa-2 in the middle of the frame.

They have not released any information about the rehearsal results. The key here is how accurately they were able to get Hayabusa-2 to approach the asteroid’s largest flat spot, a tiny 20 meter wide spot less than half the size of their original planned landing diameter. From the image, it is unclear how successful they were.

They will now spend the next two months analyzing the data from their landing rehearsals in preparation for a landing attempt in January. During this time observations will be reduced because the Sun will be between the Earth and the asteroid.

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Parker looks back at Earth

8:51 am

Earth and Moon, taken by the Parker Solar Probe

The Parker Solar Probe, flying inward towards its first close fly-by of the Sun, has looked back at the Earth and snapped its picture.

The image was captured by the WISPR (Wide-field Imager for Solar Probe) instrument, which is the only imaging instrument on board Parker Solar Probe. During science phases, WISPR sees structures within the Sun’s atmosphere, the corona, before they pass over the spacecraft.

…Zooming in on Earth reveals a slight bulge on the right side: that is the Moon, just peeking out from behind Earth. At the time the image was taken, Parker Solar Probe was about 27 million miles from Earth.

The importance of this image is that it demonstrates that the spacecraft’s camera is working properly, and that the spacecraft itself can point accurately.

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Stripes on Dione

2:55 pm

Using data produced by Cassini while orbiting Saturn scientists have discovered long narrow stripes on the moon Dione.

Dione’s linear virgae are generally long (10 to 100s of kilometers), narrow (less than 5 kilometers) and brighter than the surrounding terrains. The stripes are parallel, appear to overlie other features and are unaffected by topography, suggesting they are among the youngest surfaces on Dione.

“Their orientation, parallel to the equator, and linearity are unlike anything else we’ve seen in the Solar System,” Patthoff said. “If they are caused by an exogenic source, that could be another means to bring new material to Dione. That material could have implications for the biological potential of Dione’s subsurface ocean.”

That they cut across the topography implies strongly that they were laid down from above, after the surface irregularities were created.

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Pluto orbiter mission could also explore Kuiper belt

1:16 pm

An analysis by scientists of the orbital mechanics surrounding Pluto and Charon, combined with the use of an ion engine similar to that used by the asteroid probe Dawn, suggests that an orbiter sent to Pluto could also break from from that planet to travel out into the Kuiper Belt and explore additional objects there.

The team first discovered how numerous key scientific objectives can be met using gravity assists from Pluto’s giant satellite, Charon, rather than propellant, allowing the orbiter to change its orbit repeatedly to investigate various aspects of Pluto, its atmosphere, its five moons, and its solar wind interactions for up to several years. The second achievement demonstrates that, upon completing its science objectives at Pluto, the orbiter can then use Charon’s gravity to escape the system without using fuel, slinging the spacecraft into the Kuiper Belt to use the same electric propulsion system it used to enter Pluto orbit to then explore other dwarf planets and smaller Kuiper Belt bodies.

“This is groundbreaking,” said Stern. “Previously, NASA and the planetary science community thought the next step in Kuiper Belt exploration would be to choose between ‘going deep’ in the study of Pluto and its moons or ‘going broad’ by examining smaller Kuiper Belt objects and another dwarf planet for comparison to Pluto. The planetary science community debated which was the right next step. Our studies show you can do both in a single mission: it’s a game changer.”

The key here is a willingness to make increased use of the ion-type engine used by Dawn in its journey from the asteroids Vesta and Ceres. Such a probe could spend decades traveling from one Kuiper Belt object to the next.

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Strong India monsoons cause more hurricane landfalls in North America

10:28 am

A new study has found a correlation between the strength of the monsoon season in India and the number of hurricanes that make landfall in North America.

According to Kelly, La Niña and the Indian monsoon are correlated, but the strength of the monsoon influences the steering of hurricanes independently of La Niña fluctuations, which are responsible for changes in hurricane frequency. In other words, La Niña fluctuations may result in more Atlantic hurricanes, but strong Indian monsoons steer them further westward, making it more likely they will make landfall in the Americas.

It’s important to account for the correlation when studying hurricane steering and landfall probability.

In reading the article, ignore the propaganda promoting global warming, as the research has zero to do with that subject. It instead now provides meteorologists another clue to predicting the frequency and paths of hurricanes in the Atlantic.

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Hubble gyro problem appears fixed

8:18 am

Engineers have apparently pinpointed and fixed the issue that was causing the Hubble Space Telescope’s last back up gyroscope to operate incorrectly, making it likely that the telescope will return to full normal operations shortly.

In an attempt to correct the erroneously high rates produced by the backup gyro, the Hubble operations team executed a running restart of the gyro on Oct. 16. This procedure turned the gyro off for one second, and then restarted it before the wheel spun down. The intention was to clear any faults that may have occurred during startup on Oct. 6, after the gyro had been off for more than 7.5 years. However, the resulting data showed no improvement in the gyro’s performance.

On Oct. 18, the Hubble operations team commanded a series of spacecraft maneuvers, or turns, in opposite directions to attempt to clear any blockage that may have caused the float to be off-center and produce the exceedingly high rates. During each maneuver, the gyro was switched from high mode to low mode to dislodge any blockage that may have accumulated around the float.

Following the Oct. 18 maneuvers, the team noticed a significant reduction in the high rates, allowing rates to be measured in low mode for brief periods of time. On Oct. 19, the operations team commanded Hubble to perform additional maneuvers and gyro mode switches, which appear to have cleared the issue. Gyro rates now look normal in both high and low mode.

This is wonderful news, in that it means the telescope will once again be able to point accurately enough to continue to take sharp images across the entire sky. It also highlights how close we are now to the telescope’s demise, since it no longer has a back-up gyroscope. With the next failure, which will occur eventually, Hubble will descend into one gyroscope operations, holding off its second working gyro as a backup.

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Ariane 5 launches BepiColumbo to Mercury

12:48 am

An Arianespace Ariane 5 rocket successfully launched the joint European/Japanese BepiColumbo mission to Mercury this weekend.

BepiColombo consists of two orbiters: Japan’s Mercury Magnetospheric Orbiter (MMO) and ESA’s Mercury Planetary Orbiter (MPO), both of which will be carried together by the Mercury Transport Module (MTM).

While MPO will go into an approximately 400 x 1500 km mapping orbit around Mercury, MMO will enter a highly elliptical orbit to study the planet’s enigmatically strong magnetic field.

The leaders in the 2018 launch race:

28 China
17 SpaceX
8 Russia
8 ULA
7 Europe (Arianespace)

China still leads the U.S. in the national rankings 28 to 26.

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First interplanetary image from a cubesat

12:39 am

One of the two MarCO cubesats launched with the InSight Mars lander has successfully taken its first picture of Mars, the first such image ever taken by an interplanetary cubesat.

The image itself is not that interesting, with Mars not much more than a dot. What makes this significant is that it proves that a small, inexpensive cubesat can be built with the capability to accurately point and take photographs during an interplanetary mission. This means that the entire field of interplanetary probes is prime for major changes, shifting from big expensive and rarely launched spacecraft to small inexpensive cubesats launching frequently and it large numbers.

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Land of swiss cheese and spiders

12:04 pm

Swiss cheese on Martian south polar cap

Time for some cool images! In one of their periodic captioned releases of an interesting high resolution image, the Mars Reconnaissance Orbiter (MRO) science team this week released a picture of the strange “swiss cheese” terrain found throughout the Martian southern polar cap. (I have already highlighted in an early post the spiders that form in the south pole as the carbon dioxide evaporates.) The image to the right is a cropped section of that image, which you can see in its entirety if you click on it.

The South Polar residual cap is composed of carbon dioxide ice that persists through each Martian summer. However, it is constantly changing shape.

The slopes get more direct illumination at this polar location, so they warm up and sublimate, going directly from a solid state to a gaseous state. The gas then re-condenses as frost over flat areas, building new layers as the older layers are destroyed.

The captioned link above also included a link to a gif animation showing how this terrain has changed since 2009. The holes have become bigger, their cliffs retreating with time.

The section I highlight above not only shows the retreating swiss cheese dry ice, you can also see ghosts of several buried craters slowly becoming visible as the dry ice evaporates away.

This is only one of many images taken of the south pole by MRO. In the October archive release, I found almost two dozen, and that’s only the images taken during August of this summer. MRO takes images of the south pole regularly to track its changes, though I suspect it took more this summer because the global dust storm blocked imagery in the middle latitudes. Below and to the right is just one of these images, a particularly good illustration of the swiss cheese formation.
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A new virus that mimics polio appears in U.S.

9:14 am

Not good: Several dozen children in twenty-two U.S. states have been struck by a new polio-like virus that causes paralysis.

Sixty-two AFM cases in 22 states have been confirmed in recent weeks, scientists at the Centers for Disease Control and Prevention (CDC) in Atlanta said at a news conference today; 65 more are under investigation.

Similar waves occurred in 2014 and 2016, and scientists have fingered a relative of the poliovirus, called enterovirus D68 (EV-D68), as a possible culprit. But the evidence isn’t conclusive yet, and it’s unclear why the virus would only paralyze a small minority of children it infects. Solving these mysteries is urgent because the paralysis can be severe and irreversible. AFM is “pretty rare, but it’s pretty devastating,” says Priya Duggal, a genetic epidemiologist at Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, who’s studying whether some patients may have a genetic vulnerability to the virus. “And it appears that it’s cyclical. It’s not going away.”

It appears that in most cases the virus simply causes cold-like symptoms that go away like a cold. In a few cases, however, it produces paralysis.

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