Tag: science

A hole in space

8:48 am

A hole in space
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken by the Hubble Space Telescope and was released today as its picture of the week. From the caption:

This peculiar portrait from the NASA/ESA Hubble Space Telescope showcases NGC 1999, a reflection nebula in the constellation Orion. NGC 1999 is around 1350 light-years from Earth and lies near to the Orion Nebula, the closest region of massive star formation to Earth. NGC 1999 itself is a relic of recent star formation — it is composed of detritus left over from the formation of a newborn star.

Just like fog curling around a street lamp, reflection nebulae like NGC 1999 only shine because of the light from an embedded source. In the case of NGC 1999, this source is the aforementioned newborn star V380 Orionis which is visible at the centre of this image. The most notable aspect of NGC 1999’s appearance, however, is the conspicuous hole in its centre, which resembles an inky-black keyhole of cosmic proportions.

Once astronomers thought the black area was caused by dust, blocking the light. Now, based on a lot of new data from multiple ground- and space-based telescopes, they know that it actually is a black empty void. Why it exists however is not yet understood.

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Bedrock layers in Terby Crater on Mars

5:55 pm

Bedrock layers in Terby Crater on Mars
Click for full image.

Cool image to end the week! The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken by on July 18, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the bedrock layers on one of two very large mesas that jut out into the floor of 108-mile-wide Terby Crater.

I want to focus your eye on the spoon-shaped mesa near the top right of the photo. Note how the layers can be seen on both sides, even though the top of the mesa seems to be concave. This is strange and complex geology, made even more fascinating in that the two mesas almost reach the center of the crater floor. Why are they here? Why were they not flattened during impact, like the rest of the crater floor? Or maybe the original crater floor is the mesa top, but if so, why did the rest of the crater interior get eroded away.

The overview map below provides some context, and helps fill in some details, even if it fails to answer any of these questions.
» Read more

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Astronomers discover an exoplanet with the density of a marshmallow

10:18 am

Using ground-based telescopes to gather more data about an exoplanet discovered by the orbiting TESS telescope, astronomers have found that it has the density of a marshmallow.

The planet orbits a red dwarf star, the most common star in the universe, and is the “fluffiest” yet seen around this type of star.

Red dwarf stars are the smallest and dimmest members of so-called main-sequence stars — stars that convert hydrogen into helium in their cores at a steady rate. Though “cool” compared to stars like our Sun, red dwarf stars can be extremely active and erupt with powerful flares capable of stripping a planet of its atmosphere, making this star system a seemingly inhospitable location to form such a gossamer planet.

Astronomers remain puzzled how such a large fluffy planet could have formed around such a dim small star.

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Rate of micrometeorite impacts on Webb holding as expected

10:10 am

According to this Space.com article, the rate and size of micrometeorite impacts on the main mirror of the Webb Space Telescope has held steady at the rate and size expected, since the first surprisingly large micrometeorite impact in May that slightly dinged one mirror segment.

At this point, JWST has experienced a total of 33 micrometeoroid events, according to Smith’s slides. But the most damaging one came before JWST began science observations; in late May, a particularly large micrometeoroid struck the observatory’s mirror, leaving its mark on one golden hexagon. The team estimates that a strike of that size should occur about once a year, Smith said.

“So we got that at month five,” he said. “We haven’t seen another one yet, so it’s still consistent with the statistics that we expected.”

Smith noted that, at the current impact rate, Webb will still be meeting its five-year performance requirement 10 years into the mission. Scientists estimate that the observatory has enough fuel to operate for 20 years.

Meanwhile, one of Webb’s infrared cameras is not doing spectroscopy as engineers analyze the high levels of friction in a “grating wheel.” At this point it appears they still do not understand the cause of the friction, and thus have not come up with a plan for mitigating it.

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Chandrayaan-3 now scheduled for summer 2023

10:01 am

India’s second attempt to put a rover on the surface of the Moon, Chandrayaan-3, has now been tentatively scheduled for launch in the summer of 2023.

The launch had originally been scheduled for launch in the fall of 2020, but was delayed when India shut down due to the Wuhan panic. Official at ISRO, India’s space agency, had hoped to launch by the summer of 2022, but that proved impossible. They have now delayed the mission a full year.

In fact, all earlier reports had indicated the rover was almost ready. This new delay of a full year suggests that some new issues might have been identified.

The news article at the link also notes that ISRO is now planning two unmanned orbital missions plus four launch abort tests before launching its first manned mission, dubbed Gaganyaan, not two abort tests as previously planned. They are still targeting ’24 for the manned mission.

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InSight status: Barely hanging on

9:50 am

InSight's power status as of October 19, 2022

The science team for the InSight lander on Mars today posted an update on the power the spacecraft’s dust covered solar panels are producing. I have added that data to my on-going graph of these power levels, to the right. From the update:

On October 19, 2022, InSight was generating an average between 275 and 285 watt-hours of energy per Martian day, or sol. The tau, or level of dust cover in the atmosphere, was estimated at 1.5 (typical tau levels outside of dust season range from 0.6-0.7).

The jump in tau level is due to a large dust storm that developed in September more than two thousand miles away in the southern hemisphere. Though it is so far away, that storm put a lot more dust in the atmosphere above InSight, and forced engineers to shut down all but its most essential functions.

That storm is apparently continuing, and might even be growing. If so, the future of InSight is dim indeed. Any further drop in the amount of power it generates daily will likely make it unable to operate at all, and the mission will end.

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Frozen lava flows around Martian hills

5:06 pm

Martian lava flowing around hills
Click for full image.

Cool image time! The photo to the right, rotated, cropped, reduced, and enhanced to post here, was taken on August 24, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the westernmost edge of the Athabasca flood lava plain, thought to be the youngest lava flow on Mars, having covered the area of Great Britain in a matter of weeks 600 million years ago.

This image was a captioned feature yesterday by the MRO science team. As they note:

Although you can’t sail a boat on a sea of lava, hills and craters that stick up higher than the lava flow act like barriers. When a boat is driven through the water, there is a bow wave at the front of the boat, and a wake that trails off behind that indicates which way the boat is moving. In a lava flow, when a hill sticks up, the lava piles up on the upstream side (just like a bow wave) and can leave a wake on the downstream side, so we can tell which way the lava was moving against the stationary hill.

As you can see, every hill has a pile of lava on its northeast slopes, and a wake to its southeast. As the main vent of the Athabasca eruption is to the northeast, about 500 miles away (as shown on the overview map below), the flow direction suggested by the wakes fit the general geography.
» Read more

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Hubble spots double tail of debris from DART impact of Dimorphus

11:28 am

Dimorphus double tail
Click for original image.

A series of images taken by the Hubble Space Telescope of the ejecta released when DART crashed into the small 525-foot-wide asteroid Dimorphus has found that debris forming a double tail trailing away from the Sun.

The picture to the right, cropped, reduced, and enhanced to post here, was taken on October 11, 2022 by Hubble, and shows those two tails as close parallel debris trails.

Repeated observations from Hubble over the last several weeks have allowed scientists to present a more complete picture of how the system’s debris cloud has evolved over time. The observations show that the ejected material, or “ejecta,” has expanded and faded in brightness as time went on after impact, largely as expected. The twin tail is an unexpected development, although similar behavior is commonly seen in comets and active asteroids. The Hubble observations provide the best-quality image of the double-tail to date.

Following impact, Hubble made 18 observations of the system. Imagery indicates the second tail formed between 2-8 October 2022.

Though observations by telescope will continue for the years to follow, the real punchline to this event will be when the European probe Hera rendezvouses with the Didymous-Dimorphus pair in 2026 to perform several years of very close observations.

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A pseudo-oblique view of Jupiter’s cloud-tops

1:20 pm

A pseudo-oblique view of Jupiter's cloud-tops
Click for original image.

Cool image time! The image to the right, cropped, reduced, and annotated to post here, was created on October 18, 2022 by citizen scientist Thomas Thomopoulos from one of the photos taken by Juno during its close fly-by of Jupiter in May 2018.

He created this three dimensional relief by assigning different elevation values across the image’s greyscale, with white having the highest elevation. This relief is thus not based on actual topography, but it provides a nice way to illustrate the cloud structures of Jupiter’s cloud tops. It also, as Thomopoulos notes, provide a good way to possibly “see a representation in relief of surface movements.” Nor is his topography based on greyscale far wrong, since in many Jupiter images the lighter colored clouds are generally higher because the darker ones are in shadow.

The map below provides the context and scale of this image.
» Read more

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Moderna CEO admits to past lies: “COVID is simply the flu, harmless to the healthy.”

12:49 pm

The liar at Moderna
The liar in charge at Moderna

On October 17, 2022 during a news conference, Stéphane Bancel, the CEO of the drug company Moderna, made the following statement about COVID, the so-called plague that allowed his company (and others) to make billions pushing their jabs on a terrified public:

“I think it’s going to be like the flu. If you’re a 25-year-old, do you need an annual booster every year if you’re healthy?

“You might want to… but I think it’s going to be similar to flu where it’s going to be people at high-risk, people above 50 years of age, people with comorbidities, people with cancer and other conditions, people with transplants.”

Gee, where I have heard these exact words for the past two-plus years? Could it have been on this very same webpage, said by me as well as numerous other cool-headed experts who — rather than panicking — looked at the actual data? From my first detailed post about COVID in March 2020, using all the early real data:

The death rate is mostly confined to the older population with already existing health issues, like the flu.

This early conclusion was later confirmed again and again in the months that followed. From September 2020, for example, in citing CDC data I wrote:
» Read more

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Twelve years of data from WISE

10:43 am

The Wide Field Infrared Survey Explorer (WISE) was launched in 2009 with an intended mission of two years, during which it would map the sky looking for asteroids. In 2011 NASA extended the mission, renaming the telescope for inexplicable reasons to NEOWISE (adding “Near-Earth Object” to the beginning).

In the more than a decade since, the telescope has been able to get eighteen repeated scans of the entire sky, allowing scientists to track many changes in a variety of stellar objects over time.

Yesterday NASA issued a press release celebrating this long achievement.

Every six months, NASA’s Near-Earth Object Wide Field Infrared Survey Explorer, or NEOWISE, spacecraft completes one trip halfway around the Sun, taking images in all directions. Stitched together, those images form an “all-sky” map showing the location and brightness of hundreds of millions of objects. Using 18 all-sky maps produced by the spacecraft (with the 19th and 20th to be released in March 2023), scientists have created what is essentially a time-lapse movie of the sky, revealing changes that span a decade.

There is a bit of hype in this claim. The data isn’t really useful when looked at across the entire sky. One has to zoom into particular objects to see them evolve over time. Also, many of these changes, such as with variable stars, are well known and tracked by many other telescopes.

Nonetheless, this infrared database is very valuable. It can be used for example by astronomers to identify objects that should be viewed with high resolution in the infrared, by Webb.

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Webb takes infrared image of Hubble’s Pillars of Creation

10:28 am

The Pillars of Creation, as seen by Hubble and Webb
Click for original image.

Not unexpectedly, astronomers have quickly begun aiming the Webb Space Telescope’s infrared eye at some of the most famous targets previously imaged in optical wavelengths by the Hubble Space Telescope.

The newest example is shown to the right and reduced and labeled to post here. It shows what NASA officials dubbed “The Pillars of Creation” when Hubble first photographed this nebula in 1995, with a later 2014 Hubble optical image at the top and the new 2022 Webb infrared image on the bottom. From this image’s caption:

A new, near-infrared-light view from NASA’s James Webb Space Telescope, at [bottom], helps us peer through more of the dust in this star-forming region. The thick, dusty brown pillars are no longer as opaque and many more red stars that are still forming come into view.

While the pillars of gas and dust seem darker and less penetrable in Hubble’s view [top], they appear more diaphanous in Webb’s. The background of this Hubble image is like a sunrise, beginning in yellows at the bottom, before transitioning to light green and deeper blues at the top. These colors highlight the thickness of the dust all around the pillars, which obscures many more stars in the overall region.

In contrast, the background light in Webb’s image appears in blue hues, which highlights the hydrogen atoms, and reveals an abundance of stars spread across the scene. By penetrating the dusty pillars, Webb also allows us to identify stars that have recently – or are about to – burst free. Near-infrared light can penetrate thick dust clouds, allowing us to learn so much more about this incredible scene.

While the Hubble colors attempt to mimic the colors seen by the human eye, the colors in the Webb image are all false colors, chosen by the scientists to distinguish the different infrared wavelengths produced by different features in the picture.

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The first Greek star catalog discovered hidden in medieval parchment

10:04 am

Scientists have discovered part of the first Greek star catalog created by Hipparchus — thought by many to have invented the modern field of astronomy — hidden in a medieval parchment that had been reused for other puposes.

Scholars have been searching for Hipparchus’s catalogue for centuries. James Evans, a historian of astronomy at the University of Puget Sound in Tacoma, Washington, describes the find as “rare” and “remarkable”. The extract is published online this week in the Journal for the History of Astronomy. Evans says it proves that Hipparchus, often considered the greatest astronomer of ancient Greece, really did map the heavens centuries before other known attempts. It also illuminates a crucial moment in the birth of science, when astronomers shifted from simply describing the patterns they saw in the sky to measuring and predicting them.

The manuscript came from the Greek Orthodox St Catherine’s Monastery in the Sinai Peninsula, Egypt, but most of its 146 leaves, or folios, are now owned by the Museum of the Bible in Washington DC. The pages contain the Codex Climaci Rescriptus, a collection of Syriac texts written in the tenth or eleventh centuries. But the codex is a palimpsest: parchment that was scraped clean of older text by the scribe so that it could be reused.

Using modern multi-spectral imaging, the researchers were able to decipher the older text, and determined it was almost certainly written by Hipparchus and included his star measurements.

Read the whole article at the link. It is a fascinating detective story describing the origins of modern astronomy in western civilization.

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Inverted river on Mars

1:52 pm

Inverted river on Mars

Cool image time! The photo to the right, rotated, cropped, reduced, and enhanced to post here, was taken on May 30, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as a “inverted fluvial system”.

Such features are not unusual on Mars. The theory explaining their formation is that this was once a channel where either water or ice flowed, packing the streambed down so that it was more dense than the surrounding terrain. After the flowing material disappeared, the less dense surrounding terrain eroded away, leaving the channel as a meandering ridge.

The location of this inverted channel, as shown in the overview map below, lends some weight to the flowing material being water or ice.
» Read more

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ESA looking to SpaceX to launch Euclid space telescope

9:02 am

Capitalism in space: Having lost its Soyuz launch vehicle for its Euclid space telescope because of the Russian invasion of the Ukraine, the European Space Agency (ESA) is now looking at SpaceX as a possible option.

At a meeting of NASA’s Astrophysics Advisory Council, Mark Clampin, director of the agency’s astrophysics division, said his understanding is that the European Space Agency was leaning towards launching its Euclid mission on a Falcon 9 in mid to late 2023.

NASA is a partner on Euclid, a space telescope that will operate around the Earth-sun L-2 Lagrange point 1.5 million kilometers from Earth to study dark energy, dark matter and other aspects of cosmology. The 2,160-kilogram spacecraft was to launch on a Soyuz rocket from French Guiana in 2023.

Europe has for years used its own rockets for its science missions. However, right now the Falcon 9 appears the only option. The last launches of Europe’s Ariane-5 rocket are already assigned, and the new Ariane-6 rocket has not yet flown, is behind schedule, and its early launches are also already reserved.

Nor does ESA have other options outside of SpaceX. Of the rockets powerful enough to do the job, ULA’s Atlas-5 is also being retired, and the Vulcan rocket is as yet unavailable. Blue Origin’s New Glenn is years behind schedule, with no clear idea when it will finally launch.

A final decision is expected soon. ESA could either go with SpaceX, or simply delay several years until Ariane-6 is flying.

If SpaceX gets the job however it will once again demonstrate the value of moving fast in a competitive environment. While its competitors have dithered and thus do not have their rockets ready, SpaceX has been flying steadily for years, so it gets the business.

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After 30 years the Geotail solar probe appears dead

8:01 pm

Launched in 1992 as a joint U.S./Japan project to study the tail of the Earth’s magnetosphere, the Geotail solar mission appears to be over, though engineers continue to work the problem.

Originally, Geotail was equipped with two data recorders to collect the mission’s scientific data. One data recorder failed in 2012 after 20 years of gathering information about the plasma environment around Earth. The remaining data recorder continued collecting data for 10 more years until it experienced an anomaly on June 28, 2022.

The team at JAXA discovered the error with the recorder and have been performing tests to investigate the cause and extent of the damage. Ongoing attempts to recover the recorder have been unsuccessful. Without a functioning recorder, the science data from the U.S. instruments can no longer be collected or downlinked. NASA, ISAS, and JAXA are deciding the best path forward for the mission given the failure.

When the solar wind hits the Earth’s magnetosphere, it pushes it away so that on the side away from the Sun a tail forms, almost like the wake of a ship.

Without any way to download the spacecraft’s data, however, Geotail’s value as a scientific probe is extremely limited. If engineers can still control it and adjust its orbit, however, then it might still be useful for a variety of engineering and orbital flight tests.

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Jets from baby stars

12:12 pm

Jets from baby stars
Click for full image.

Cool image time! The picture to the right, rotated and reduced to post here, was taken across multiple wavelengths by the Hubble Space Telescope and shows two different Herbig–Haro objects (HH 1 at the top and HH 2 on the bottom). Herbig-Haro objects are the bright cloud clumps found near newly formed baby stars. These particular clouds are about 1,250 light years away. The jets flowing away from HH 1 are speeding away at about 250 miles per second.

Note that the baby stars themselves are not visible, buried in the dust that surrounds them. The bright star in the upper right is an unrelated foreground star.

In the case of HH 1/2, two groups of astronomers requested Hubble observations for two different studies. The first delved into the structure and motion of the Herbig–Haro objects visible in this image, giving astronomers a better understanding of the physical processes occurring when outflows from young stars collide with surrounding gas and dust. The second study instead investigated the outflows themselves to lay the groundwork for future observations with the NASA/ESA/CSA James Webb Space Telescope. Webb, with its ability to peer past the clouds of dust enveloping young stars, will revolutionise the study of outflows from young stars.

There is a lot of complexity here that this image only hints at. Note for example the smaller cloud objects near HH1, the shape of which suggest a shaping by some interstellar wind.

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OSIRIS-REx does mid-course correction

8:36 am

To better refine its path back to Earth in order to properly aim its sample return capsule, engineers had OSIRIS-REx do a short successful 30 second engine burn on September 21, 2022.

Nor will this be the only course correction prior to sample return on September 24, 2023 in Utah.

To ensure a safe delivery, “Over the next year, we will gradually adjust the OSIRIS-REx trajectory to target the spacecraft closer to Earth,” said Daniel Wibben, trajectory-and-maneuver design lead with KinetX Inc. “We have to cross Earth’s orbit at the time that Earth will be at that same location.” Wibben works closely with the Lockheed Martin team in Littleton, Colorado, that flies the spacecraft.

Last month’s maneuver was the first time the OSIRIS-REx team changed the spacecraft’s trajectory since it left Bennu on May 10, 2021. Following this course adjustment, OSIRIS-REx would pass about 1,367 miles (2,200 kilometers) from Earth. A series of maneuvers beginning in July 2023 will bring OSIRIS-REx even closer, to 155 miles (250 kilometers) off the surface, close enough to release its sample capsule for a precision landing – via parachute at the Air Force’s Utah Test and Training Range in the Great Salt Lake Desert.

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Two solar eclipses coming to the U.S. next year

12:47 pm

The next eclipses to cross the U.S.
Map by Michael Zeiler (GreatAmericanEclipse.com). Click for original.

The U.S. public will get to see two different solar eclipses during a six month period, starting one year from today.

The map to the right, cropped and reduced to post here, shows the dates and the path of both eclipses.

On 14 October 2023, anyone under clear skies within a path that sweeps from Oregon to Texas and then through parts of Central and South America will see an annular (“ring”) eclipse. Just six months later, on 8 April 2024, a total solar eclipse will sweep from Mexico to Texas to the Canadian Maritimes, plunging day into night and revealing the magnificent solar corona for anyone fortunate to be within the path of totality and under clear skies. Nearly everyone in North America will have a partial solar eclipse both days.

As always with eclipses, great care must be taken to watch it. With the 2017 eclipse Diane and I had good filters, but even so I noticed my eyes were very tired for several days afterward.

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Perseverance spots Phobos

10:57 am

Phobos, as seen by Perseverance on Mars
Click for full image.

Cool image time! The photo to the right, cropped to post here, was taken on January 12, 2022 by one of the high resolution cameras on the Mars rover Perseverance, and shows the Martian moon Phobos.

As noted in an update today by Claire Newman, one of the members of the science team,

This provides a measurement, using visible light, of the amount of dust in the nighttime atmosphere, which can be compared to similar measurements made by looking at the sun during the daytime, and to nighttime measurements of dust abundance made in the infrared by MEDA [another Perseverance instrument].

There have been three attempts to land on Phobos, all by the Russians, all of which failed. At present a Japanese mission to Phobos, dubbed Mars Moons eXploration or MMX, is scheduled to launch in 2024. This is a planned sample return mission, and will also include a rover.

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Lucy to fly past Earth on October 16th

10:13 am

Lucy solar panel graphic
Artist’s impression of solar panel

As part of its planned route to get to the Trojan asteroids in Jupiter’s orbit, the planetary probe Lucy is scheduled to fly only 220 miles above the Earth’s surface on October 16th.

Lucy will be passing the Earth at such a low altitude that the team had to include the effect of atmospheric drag when designing this flyby. Lucy’s large solar arrays increase this effect.

“In the original plan, Lucy was actually going to pass about 30 miles closer to the Earth,” says Rich Burns, Lucy project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “However, when it became clear that we might have to execute this flyby with one of the solar arrays unlatched, we chose to use a bit of our fuel reserves so that the spacecraft passes the Earth at a slightly higher altitude, reducing the disturbance from the atmospheric drag on the spacecraft’s solar arrays.”

That solar array remains unlatched (as shown in the graphic above), but because it is almost completely deployed and is producing about 90% of its intended electricity, engineers have ceased efforts to complete deployment and latching.

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Final decision: Arecibo will not be rebuilt

3:34 pm

The National Science Foundation has made it official: It will not rebuild the Arecibo Observatory in Puerto Rico, though it will fund the facility as an education center instead.

Now, the National Science Foundation (NSF), which owns the site, has determined that despite scientists’ pleas, Arecibo Observatory won’t be getting any new telescope to replace the loss. The new education project also doesn’t include any long-term funding for the instruments that remain operational at the observatory, including a 40-foot (12 m) radio dish and a lidar system.

…Instead, the NSF intends to build on the observatory’s legacy as a key educational institution in Puerto Rico by transforming the site into a hub for science, technology, engineering and math (STEM) education, due to open in 2023, according to a statement. The observatory is also home to the Ángel Ramos Foundation Science and Visitor Center, which opened in 1997.

It seems unclear how this education center will function. Will it be a school that students attend? Or simply a type of museum with a visitors center? This new plan appears to call for about $2 million per year in funding, which does not appear enough to do much of anything, other than to keep the lights on and hang some pretty astronomy pictures on the walls.

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Changing slope streaks on Mars

3:08 pm

Overview map

Changing slope streaks on Mars
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken on July 20, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists have labeled a “Splitting Slope Streak” on a mound/hill near the equator and located almost midpoint between the giant volcano Olympus Mons about 2,000 miles to the east and the almost as big volcano Elysium Mons about 2,500 miles to the west. The white cross on the overview map above marks this location, north of the Medusae Fossae volcanic ash deposit.

The slope streak in question is the biggest and darkest at about 7 o’clock. Slope streaks are a feature unique to Mars that remain as yet unexplained. They are not ordinary avalanches, despite their appearance. They seem to have no effect on the topography, and thus are more a stain on the surface. Moreover, some are bright, some dark, and all happen randomly and fade with time. Some think they may be brine-related, while others link them to dust. No theory explains them completely.

What makes this slope streak interesting is that it is relatively new. Compare it with the picture taken in 2016 below.
» Read more

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The known near Earth asteroid catalog now tops 30,000

9:35 am

Chart of NEA's discovered over time

The catalog of known near Earth asteroids that have been identified using a number of survey telescopes in space and on the Earth now totals 30,039. As defined at the link:

An asteroid is called a near-Earth asteroid (NEA) when its trajectory brings it within 1.3 Astronomical Units (au) of the Sun. 1 au is the distance between the Sun and Earth, and so NEAs can come within at least 0.3 au, 45 million km, of our planet’s orbit.

Currently, near-Earth asteroids make up about a third of the roughly one million asteroids discovered so far in the Solar System. Most of them reside in the asteroid belt between Jupiter and Mars.

NEAs are also called NEOs (Near Earth Objects). The chart above, produced by the Center for NEO Studies which tracks these objects, shows the number of NEAs discovered over time.

Of the 30,039 now known, about 1,400 have orbits with “a non-zero” chance of hitting the Earth. None however will do so in the next hundred years at least.

Though the pace of discovery is vastly improving — as indicated by the steep rise in the curve in the graph — only when that curve begins to flatten out will we know that we are getting close to having a more-or-less complete survey of these objects.

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TESS enters safe mode

9:18 am

The science team for TESS (Transiting Exoplanet Survey Satellite) revealed yesterday that the spacecraft had entered safe mode on October 10th.

The spacecraft is in a stable configuration that suspends science observations. Preliminary investigation revealed that the TESS flight computer experienced a reset. The TESS operations team reported that science data not yet sent to the ground appears to be safely stored on the satellite. Recovery procedures and investigations are underway to resume normal operations, which could take several days.

TESS has been in orbit since 2018, where it has been repeatedly taking survey images of the entire sky. Astronomers then compare these images to see if they can spot exoplanet transits (as well as any other new phenomenon). So far 250 exoplanets have been identified.

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An icy hollow on Mars

2:07 pm

A icy hollow on Mars
Click for full image.

Cool image time! The photo to the right, cropped, reduced, and enhanced to post here, was taken on August 20, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a somewhat typical example of the many ice scarps that scientists have identified in MRO pictures.

Though this is not a hard fast rule, most of the ice scarps so far found tend to have the steep cliff on the pole-facing side, with the scarp very slowly retreating towards the equator. In today’s example, the scarp where an ice layer in the cliff wall has been identified is indicated by the white arrow, though three sides of the hollow, on the east, north, and west sides, could all also have exposed ice.

Nor is that the only likely ice at this location at 56 degrees south latitude. The stippled plain surrounding the hollow clearly looks like an eroded ice layer, likely covered with a thin protective coat of dust to protect if from quickly sublimating away. The dark streaks across this surface are likely dust devil tracks.

As documented by the global map below, Mars is like Antarctica, a desert with water ice everywhere.
» Read more

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Shells of dust surrounding massive binary star

10:07 am

Webb infrared image of dust shells surrounding binary star system
Click for full image.

Cool image time! Using the Webb telescope, astronomers have detected a series of concentric shells surrounding the massive binary star dubbed Wolf-Rayet 140.

The infrared image to the right shows these shells quite clearly. As noted by astronomer Ryan Lau:

“On the night that my team’s Early Release Science observations of the dust-forming massive binary star Wolf-Rayet (WR) 140 were taken, I was puzzled by what I saw in the preview images from the Mid-Infrared Instrument (MIRI). There seemed to be a strange-looking diffraction pattern, and I worried that it was a visual effect created by the stars’ extreme brightness. However, as soon as I downloaded the final data I realized that I was not looking at a diffraction pattern, but instead rings of dust surrounding WR 140 – at least 17 of them.

“I was amazed. Although they resemble rings in the image, the true 3D geometry of those semi-circular features is better described as a shell. The shells of dust are formed each time the stars reach a point in their orbit where they are closest to each other and their stellar winds interact. The even spacing between the shells indicates that dust formation events are occurring like clockwork, once in each eight-year orbit. In this case, the 17 shells can be counted like tree rings, showing more than 130 years of dust formation. Our confidence in this interpretation of the image was strengthened by comparing our findings to the geometric dust models by Yinuo Han, a doctoral student at the University of Cambridge, which showed a near-perfect match to our observations.

Furthermore, the spectroscopy from Webb says these dust shells are carbon-enriched, showing that the dust released by these aged massive stars is a significant source of the carbon in the universe, the fundamental atom needed for life.

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DART’s impact shortened Dimorphus’s orbit around Didymos by 32 minutes

5:51 pm

LICIACube Explorer image of DART impact
LICIACube Explorer image just after the DART
impact. Dimorphus is the blob near the top.

After two weeks of analyzing the orbit of Dimorphus around its parent asteroid Didymos, astronomers have determined that the impact of DART on Dimorphus shortened its orbit by 32 minutes.

Prior to DART’s impact, it took Dimorphos 11 hours and 55 minutes to orbit its larger parent asteroid, Didymos. Since DART’s intentional collision with Dimorphos on Sept. 26, astronomers have been using telescopes on Earth to measure how much that time has changed. Now, the investigation team has confirmed the spacecraft’s impact altered Dimorphos’ orbit around Didymos by 32 minutes, shortening the 11 hour and 55-minute orbit to 11 hours and 23 minutes. This measurement has a margin of uncertainty of approximately plus or minus 2 minutes.

Before its encounter, NASA had defined a minimum successful orbit period change of Dimorphos as change of 73 seconds or more. This early data show DART surpassed this minimum benchmark by more than 25 times.

It also appears the ejecta from the impact — much greater than expected — helped propel Dimorphus, a result that I think was also not expected.

Researchers are now shifting to studying the debris and asteroid itself, to better understand what happened as well as the nature of Dimorphus itself. This will also include a European probe dubbed Hera that will launch in 2024 an dvisit both asteroids in 2026.

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Webb gets first direct infrared image of exoplanet

10:21 am

Exoplanet as seen in the infrared by Webb

Using the Webb Space Telescope, scientists have obtained that telescope’s first direct infrared image of an exoplanet, covering four different wavelengths.

The image to the right is from the wavelength image with the least distortion (formed by Webb’s own optics and the shape of its mirror and indicated by the faint ring surrounding the planet). The star indicates the masked location of the star itself.

The planet is about seven times the mass of Jupiter and lies more than 100 times farther from its star than Earth sits from the sun, direct observations of exoplanet HIP 65426 b show. It’s also young, about 10 million or 20 million years old, compared with the more than 4-billion-year-old Earth.

You can download the full research paper here.

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