Tag: astronomy

First attempts to fix Hubble fail

9:43 am

An attempt to switch the Hubble Space Telescope to a different backup computer module in order to bypass a broken unit failed last week, leaving the telescope in safe mode.

A payload computer on Hubble stopped working June 13, the agency said in a June 16 statement. Engineers speculated that the computer, used to manage operations of Hubble’s science instruments, malfunctioned because of a degrading memory module, putting the instruments into a safe mode.

The agency said at the time that it would switch of a backup memory module that day and, after about a day of testing, restart the instruments and resume science observations.

However, in a June 18 statement, NASA said those efforts to switch to a backup memory module failed because “the command to initiate the backup module failed to complete.” An attempt to restore the computer with both the original memory module and the backup unit also failed.

While the engineers at the Space Telescope Science Institute, that operates Hubble, have expressed confidence they can overcome these issues, the failures this week are truly troublesome. We may truly be facing the end of the telescope,

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New data confirms lack of dark matter in one galaxy

12:00 pm

The uncertainty of science: Astronomers have strengthened their evidence that one particular nearby galaxy is completely devoid of dark matter, a situation that challenges the existing theories about dark matter which suggest it comprises the bulk of all matter in the universe.

The astronomers had made their first claim that this galaxy, NGC 1052-DF2, lacked dark matter back in 2018, a claim that was strongly disputed by others.

The claim however would only hold up if the galaxy’s distance from Earth was as far away as they then estimated, 65 million light years (not the 42 million light years estimated by others). If it were closer, as other scientists insisted, then NCC 1052-DF2 likely did have dark matter, and the theorists could sleep at night knowing that their theory about dark matter was right.

To test their claim, the astronomers used the Hubble Space Telescope to get a better, more tightly constrained estimate of the distance, and discovered the galaxy was even farther away then previously believed.

Team member Zili Shen, from Yale University, says that the new Hubble observations help them confirm that DF2 is not only farther from Earth than some astronomers suggest, but also slightly more distant than the team’s original estimates.

The new distance estimate is that DF2 is 72 million light-years as opposed to 42 million light-years, as reported by other independent teams. This places the galaxy farther than the original Hubble 2018 estimate of 65 light-years distance.

So, does this discovery invalidate the theories about dark matter? Yes and no. The theories now have to account for the existence of galaxies with no dark matter. Previously it was assumed that dark matter was to be found as blobs at the locations of all galaxies. Apparently it is not.

However, the lack of dark matter at this one galaxy does not prove that dark matter is not real. As noted by the lead astronomer in this research,

“In our 2018 paper, we suggested that if you have a galaxy without dark matter, and other similar galaxies seem to have it, that means that dark matter is actually real and it exists,” van Dokkum said. “It’s not a mirage.

Ah, the uncertainty of science. Isn’t it wonderful?

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Astronomers propose explanation the dimming of Betelgeuse in 2020

10:01 am

The uncertainty of science: New data has allowed astronomers to propose a more detailed explanation for the dimming of Betelgeuse in 2020 by almost two-thirds.

[T]he dimming was likely to be caused by [one of two] mechanisms, such as a blob of unusually cold matter appearing on the surface of the star in what’s known as a convective cell, or a cloud of dust crossing the line of sight to it.

Now, astrophysicist Miguel Montargès at the Paris Observatory and his collaborators have found that the reason for the ‘great dimming’ was probably a combination of both of those factors

The data suggest that the star spewed out material from a convection cell, which then quickly condensed into dust which acted to block the star’s light. The growing cell itself also was darker, which also contributed to the dimming.

The results, while robust, are still uncertain. While a number of mainstream news sources are claiming the mystery of Betelgeuse’s dimming has been “solved”, that is not how it works. The data now points to an answer, but the data is far from complete, and future observations could very easily change that answer.

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Hubble in safe mode due to computer problem

1:47 pm

A computer failure on June 13th put the Hubble Space Telescope in safe mode, with engineers hoping to have the problem resolved and the telescope back in operation by tomorrow.

NASA is working to resolve an issue with the payload computer on the Hubble Space Telescope. The computer halted on Sunday, June 13, shortly after 4 p.m. EDT. After analyzing the data, the Hubble operations team is investigating whether a degrading memory module led to the computer halt. The team is preparing to switch to one of several backup modules on Wednesday, June 16. The computer will then be allowed to run for approximately one day to verify that the problem has been solved. The team would then restart all science instruments and return the telescope to normal science operations.

The unit itself, while built in the 1980s, was only launched to Hubble in 2009 as part of the last shuttle repair mission.

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Third set of new results from Parker released

9:32 am

The scientists using the Parker Solar Probe on June 2nd released their third set of new results as part of a special issue of the journal Astronomy & Astrophysics.

The latest articles include data analysis, theory, and modeling. Among the major topics covered are magnetic switchbacks first discovered by Parker Solar Probe, the role of waves in heating solar plasma, solar angular momentum, the near-Sun dust environment, and the diversity of small energetic-particle events.

The most interesting paper I think is the one describing data that lends strong weight to the theory, proposed in 1929 by astronomer Henry Norris Russell, that a dust-free zone exists close to the Sun and all stars. From the abstract:

The observed brightness decrease in the axis of symmetry is interpreted as the signature of the existence of a dust density depletion zone between about 19 [solar radii] and 3 [solar radii] which at the inner limit of WISPR’s field of view of 7.65 [solar radii] has a dust density that is ~5% lower than the density at 19 [solar radii], instead of the expected density which is three times if no depletion zone exists.

In plain English, the data shows that from about 1.3 million to 8.2 million miles from the Sun Parker found far less dust than predicted by other models. As the probe continues to lower its orbit and get closer to the Sun with each fly-by these numbers will be better refined, and are likely to in the end prove Russell’s hypothesis.

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Problem with Ariane 5 rocket causes Arianespace to delay Webb telescope launch

9:08 am

As first revealed in mid-May, Arianespace has been forced to delay the launch of the James Webb Space Telescope by at least one month because of a problem with the fairing on its Ariane 5 rocket, found during an August 2020 launch.

There have been no Ariane 5 launches since. According to yesterday’s press briefing, however:

“The origin of the problem has been found. Corrective actions have been taken,” Daniel de Chambure, acting head of Ariane 5 adaptations and future missions at ESA, said. “The qualification review has started, so we should be able to confirm all that within a few days or weeks.” He did not elaborate on the problem or those corrective actions, beyond stating that the problem took place during separation of the payload fairing. Industry sources said in May that, on the two launches, the separation system imparted vibrations on the payload above acceptable limits, but did not damage the payloads.

It appears this new delay to Webb’s launch is because two commercial payloads must lift off first before Webb, with the first now scheduled for July. According to Arianespace, it will take two months prep for the next commercial launch, followed by two months prep for the Webb launch. That puts the launch of Webb in November.

Overall this particular delay is slight, only a few weeks, and pales in comparison to the ten years of delays experienced by NASA during development and construction of Webb. It also will add very little to the telescope’s overall budget, which has grown from an original price of $500 million to now about $10 billion.

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A lopsided spiral galaxy

12:54 pm

Losided spiral galaxy
Click for full image.

For a change, today’s cool image is not from Mars, but instead goes deep into space. The photo to the right, reduced to post here, was taken by the Hubble Space Telescope of the relatively nearby spiral galaxy NGC 2276, located about 120 million light years away. As the caption explains:

The magnificent spiral galaxy NGC 2276 looks a bit lopsided in this Hubble Space Telescope snapshot. A bright hub of older yellowish stars normally lies directly in the center of most spiral galaxies. But the bulge in NGC 2276 looks offset to the upper left.

In reality, a neighboring galaxy to the right of NGC 2276 (NGC 2300, not seen here) is gravitationally tugging on its disk of blue stars, pulling the stars on one side of the galaxy outward to distort the galaxy’s normal fried-egg appearance. This sort of “tug-of-war” between galaxies that pass close enough to feel each other’s gravitational pull is not uncommon in the universe. But, like snowflakes, no two close encounters look exactly alike.

The scientists also note that the bright edge along the galaxy’s north and west perimeter mark regions of intense star-formation. In those same regions astronomers six years ago identified the first medium-sized black hole ever found.

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New Chandra mosaic of galactic center reveals spider-web of magnetism

10:19 am

Magnetic field line at the galactic center
Click for full image.

Scientists today released a spectacular panorama of the center of the Milky Way using X-ray data from the Chandra X-ray Observatory and radio data from the MeerKAT radio telescope in South Africa. The panorama reveals a complex web of magnetic field lines emanating out from the supermassive black hole at the center, Sagittarius A* (pronounced A-star).

Below the fold are reduced versions of the full panorama, unlabeled on the left and labeled on the right. The image to the right, reduced to post here, shows just one single example of those magnetic field lines, dubbed G0.17-0.41 and about 20 light years long. This particular filament is the subject of a paper just published in connection with the release of this panorama. From the press release.

A new study of the X-ray and radio properties of this thread by Q. Daniel Wang of the University of Massachusetts at Amherst suggests these features are bound together by thin strips of magnetic fields. This is similar to what was observed in a previously studied thread. (Both threads are labeled with red rectangles in the [full labeled panorama]. The newly studied one in the lower left, G0.17-0.41, is much farther away from the plane of the Galaxy.) Such strips may have formed when magnetic fields aligned in different directions, collided, and became twisted around each other in a process called magnetic reconnection. This is similar to the phenomenon that drives energetic particles away from the Sun and is responsible for the space weather that sometimes affects Earth.

The image below is fascinating to study because of the wealth of detail it includes, not only of magnetic filaments but of other nearby gas clouds and Sagittarius A* itself.
» Read more

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More delays for Webb telescope?

8:53 am

An issue with the fairing release on the last two Ariane 5 launches has not only paused use of that rocket since August 2020, it might cause another delay in the planned October 31, 2021 launch of the James Webb Space Telescope.

In a statement to SpaceNews, Arianespace acknowledged that “post-flight analyses conducted on two recent Ariane 5 launches have indicated the occurrence of a less than fully nominal separation of the fairing, however with no adverse impact on the Ariane 5 flights in question.”

The company did not elaborate on the problem, but industry sources familiar with the issue said that, on both the August 2020 launch and the previous Ariane launch in February 2020, the separation of the faring induced vibrations into the payload stack well above acceptable limits. Neither incident damaged any of the payloads, but raised concerns about the effect on future missions, including JWST.

Moreover, Arianespace has two Ariane 5 launches on its schedule that are supposed to launch before Webb. If those are delayed it puts a further squeeze on the Webb launch date.

Meanwhile, the final checkouts of the Webb telescope have been proceeding, including a successful test of the unfolding of the telescope’s segmented mirror.

After a more than decade of delays and budget overruns — raising this telescope’s budget from 1/2 billion to $10 billion — it appears that Webb’s final schedule delay might occur not because of the telescope but because of the rocket.

In addition, the issue at Arianespace appears to be seriously impacting that company’s ’21 launch schedule, having failed to launch any Ariane 5 rockets so far this year.

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Breakthrough Listen finds no signs of alien transmissions from 60 million stars

1:25 pm

Where are those alien civilizations? Breakthrough Listen, a privately funded project searching for evidence of alien life, has released the first results from its survey of 60 million stars in an area looking towards the galactic center, noting that it found no evidence of any technological transmissions signaling an alien civilization from any of those stars.

The paper can be downloaded here [pdf].

The kind of signals they were looking for were not beacons sent out intentionally by alien civilizations, such as television or radio broadcasts, but unintentional transmissions, such as radar transmissions meant for other purposes but still beamed into space. They found none.

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Jupiter’s changing and unchanging Great Red Spot

9:40 am

The changing Great Red Spot of Jupiter
Click for full figure.

In a paper published in March in the Journal of Geophysical Research: Planets, scientists (using images from amateurs, the Hubble Space Telescope, and Juno, scientists) have mapped out the interactions between Jupiter’s Great Red Spot, the longest known storm on the gas giant, and the smaller storms that interact with it as they zip past.

The series of images to the right come from figure 5 of their paper, showing the Spot over a period of three days. The Spot in these images is about 9,000 miles across, less than half the size it had been back in the late 1800s.

The black arrows mark the shifting location and shape of one smaller vortice as it flowed past the Spot from east to west along its northern perimeter, ripping off portions of the Spot as it passed. From the paper’s absract:

During its history, the [Great Red Spot] has shrunk to half its size since 1879, and encountered many smaller anticyclones and other dynamical features that interacted in a complex way. In 2018–2020, while having a historically small size, its structure and even its survival appeared to be threatened when a series of anticyclones moving in from the east tore off large fragments of the red area and distorted its shape. In this work, we report observations of the dynamics of these interactions and show that as a result the [Spot] increased its internal rotation velocity, maintaining its vorticity but decreasing its visible area, and suffering a transient change in its otherwise steady 90‐day oscillation in longitude.

…From the analysis of the reflectivity of the [Spot] and flakes and model simulations of the dynamics of the interactions we find that these events are likely to have been superficial, not affecting the full depth of the [Spot]. The interactions are not necessarily destructive but can transfer energy to the [Spot], maintaining it in a steady state and guaranteeing its long lifetime.

In other words, the changes seen only involved the Spot’s cloud tops, even if those tops were many miles thick. The storm itself is much deeper, with its base embedded strongly inside Jupiter and largely unaffected by these passing smaller storms.

Why the Spot exists and remains so long-lived remains an unsolved mystery.

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Astronomers detect largest flare ever, on Proxima Centauri

10:43 am

In May 2019 astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have detected the largest flare ever seen from any star, including our Sun, on the nearest star, the red dwarf Proxima Centauri.

The detection was 100 times stronger than the Sun’s typical flares.

In May 2019, Proxima Centauri ejected a violent flare that lasted just seven seconds, but generated a surge in both ultraviolet and millimeter wavelengths. The flare was characterized by a strong, impulsive spike never before seen at these wavelengths. The event was recorded by five of the nine telescopes involved in the study, including the Hubble Space Telescope (HST) in ultraviolet, and ALMA in millimeter wavelengths. “The star went from normal to 14,000 times brighter when seen in ultraviolet wavelengths over the span of a few seconds,” said MacGregor, adding that similar behavior was captured in millimeter wavelengths by ALMA at the same time.

Red dwarfs are known to issue very powerful flares, a high solar activity that would likely make life as we know it impossible on any Earth-sized planet in its habitable zone, since the star’s small size and dimness requires that zone to be so close to the star. This powerful flare only cements this reality. The exoplanets that have been found circling Proxima Century will therefore not be great places for life, though building the first interplanetary colony there might make sense.

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X-rays from Uranus detected for the 1st time

10:02 am

Composite Uranus image of X-ray and optical data

Astronomers using the Chandra X-ray Observatory in orbit have for the first time detected X-rays coming from the planet Uranus.

In the new study, researchers used Chandra observations taken in Uranus in 2002 and then again in 2017. They saw a clear detection of X-rays from the first observation, just analyzed recently, and a possible flare of X-rays in those obtained fifteen years later. The main graphic [posted to the right] shows a Chandra X-ray image of Uranus from 2002 (in pink) superimposed on an optical image from the Keck-I Telescope obtained in a separate study in 2004. The latter shows the planet at approximately the same orientation as it was during the 2002 Chandra observations.

What could cause Uranus to emit X-rays? The answer: mainly the Sun. Astronomers have observed that both Jupiter and Saturn scatter X-ray light given off by the Sun, similar to how Earth’s atmosphere scatters the Sun’s light. While the authors of the new Uranus study initially expected that most of the X-rays detected would also be from scattering, there are tantalizing hints that at least one other source of X-rays is present.

One explanation could be that the X-rays could be coming from Uranus’s rings, as such X-rays do from Saturn. This is not confirmed as yet however. More data will be needed.

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Radar images of Apophis during its March close approach of Earth

9:45 am

Apophis as seen by radar March 9, 2021
Click for full image.

Using two radar dishes, Green Bank in West Virginia and Goldstone in California, astronomers were able to produce radar images of the asteroid Apophis during its most recent close fly-by of Earth on March 10th.

The image to the right, cropped and reduced to post here, shows Apophis on March 9th. If you go to the full image you can also see the March 10th and 11th images, which appear to show the asteroid in different orientations as it rotated.

These images represent radar observations of asteroid 99942 Apophis on March 8, 9, and 10, 2021, as it made its last close approach before its 2029 Earth encounter that will see the object pass our planet by less than 20,000 miles (32,000 kilometers). The 70-meter radio antenna at the Deep Space Network’s Goldstone Deep Space Communications Complex near Barstow, California, and the 100-meter Green Bank Telescope in West Virginia used radar to precisely track Apophis’ motion. At the time of these observations, Apophis was about 10.6 million miles (17 million kilometers) from Earth, and each pixel has a resolution of 127 feet (38.75 meters).

The data obtained has firmly removed any chance Apophis will impact the Earth in the next 100 years. However, it still could hit us late in the 22nd century.

These observations were originally planned to also include data from the Arecibo Observatory, but that telescope was destroyed in December when its instrument platform collapsed. If it had been operational, these radar images would have had much better resolution.

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The 1st image of a black hole’s magnetic field

8:54 am

The magnetic field lines of a black hole

Using the data from the first image of a black hole, obtained in 2019, scientists have now extracted evidence of the magnetic field lines near the event horizon, and from this produced the first image of such lines.

The image to the left, reduced to post here, shows the spiraling magnetic field lines against the bright event horizon ring.

As the Event Horizon Telescope (EHT) team describes today in a pair of papers in Astrophysical Journal, the new picture uses the same data as in the original image, produced from a series of observations in 2017 of the supermassive black hole at the core of nearby galaxy M87, using the combined collecting power of eight radio observatories across the world. To extract the polarization information, the data have gone through many months of additional analysis.

The scientists also note that the orientation of the field lines might eventually help explain the jets being thrown from its poles.

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NASA confident Webb will launch in October

9:36 am

In a briefing held yesterday, NASA officials — in summarizing the status of the James Webb Space Telescope — stated they were presently confident that its launch will take place in October this year, as presently planned.

[Eric Smith, JWST program scientist> said the program is dealing with one new technical issue. Two communications transponders suffered separate problems during testing in January. Engineers have tracked down the problems with the two units and started repairs this week. “Those boxes will be back in time for us to make our planned shipping date,” he said.

That issue, he acknowledged, will use some of the remaining schedule margin. “The plan right now is that we’ll get them back in time so that we don’t have to use all of it,” he said. “That’s the main thing that we’re watching regarding the margin.”

If launched in October, Webb will only be a decade behind schedule and a mere 20 times over budget, having been initially proposed to launch in 2011 for a cost of $500 million. Instead, it will cost about $10 billion.

The article also notes that the Biden administration might change the telescope’s name because Webb as a bureaucrat early in his career apparently publicly opposed homosexual rights. Such opinions can no longer be allowed, and anyone who has them must be blackballed as quickly as possible.

No matter. Webb was merely NASA’s administrator through almost its entire first decade, leading the agency in its triumph over the Soviets in the race to the Moon. Such achievements cannot be honored as they illustrate the past greatness of America. Moreover, Webb was a white man, and this makes him totally unqualified to receive any laurels. Today’s modern America hates itself and all white men.

The article also notes a variety of issues that will cause more delays of the new big astronomy boondoggle at NASA, the Roman Space Telescope. They say its launch will likely be delayed to 2026 because of the Wuhan flu panic. I predict this is only a foretaste. Expect many more delays and budget overruns, probably pushing its launch into the 2030s.

But no matter. What is really important is that this new boondoggle is named for a woman!

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The changing seasons of Saturn

1:58 pm

Saturn changing
Click for full image.

Images of Saturn taken by the Hubble Space Telescope since 2018 now reveal the slow seasonal changes to the gas giant’s atmosphere during its lengthy year, twenty-nine Earth years long.

The Hubble data show that from 2018 to 2020 the equator got 5 to 10 percent brighter, and the winds changed slightly. In 2018, winds measured near the equator were about 1,000 miles per hour (roughly 1,600 kilometers per hour), higher than those measured by NASA’s Cassini spacecraft during 2004-2009, when they were about 800 miles per hour (roughly 1,300 kilometers per hour). In 2019 and 2020 they decreased back to the Cassini speeds. Saturn’s winds also vary with altitude, so the change in measured speeds could possibly mean the clouds in 2018 were around 37 miles (about 60 kilometers) deeper than those measured during the Cassini mission. Further observations are needed to tell which is happening.

The photo above shows Saturn’s northern hemisphere in 2018, 2019, and 2020. Note how the darker region at the pole grows with time.

This data supplements the data obtained by Cassini when it was in orbit around Saturn, and is presently the best information we can get since the Cassini mission ended.

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Hubble’s wide field camera returns to operation

1:39 pm

Though the Hubble Space Telescope returned to science operations on March 12th after going into safe mode, its wide field camera did not.

Engineers however now report that they have successfully restored the camera to operations as well. The reason for the delayed restoration exemplifies Hubble’s aging status.

Analysis showed that voltage levels in WFC3 power supplies have slowly decreased over time as their electronics aged. The electronics experience colder temperatures when the hardware is turned off in safe mode. This factor coupled with the power the instrument components draw as they are turned back on contributed to the small voltage fluctuation that suspended WFC3 recovery operations. Further detailed analysis indicated that it would be safe to slightly reduce the low voltage limit to avoid a future suspend, and it would be safe to recover the instrument to its science state.

The instrument has now been safely recovered. Standard calibration of the instrument and other pre-observation activities will be conducted this week.

All the telescope’s equipment has been adjusted in recent years to deal with the varying ages of its instruments and its main structure. For example, this wide field camera was installed during the last shuttle serving mission in 2009, and is therefore one of Hubble’s newest components. It however is now more than a decade old, and thus needs careful handling to function properly.

Other components are far older, such as the primary motor to open and close the telescope’s “lens cap”. That failed during this safe mode, forcing engineers to switch to a back up motor to control the cap. Whether they can recover that primary motor is presently unclear, though unlikely.

Expect more such issues in the coming years.

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Hubble about to resume science operations even with new issues

9:14 am

Engineers have fixed the computer software issue that caused the Hubble Space Telescope to go into safe mode this week, and are preparing it to return to full science operations.

It appears the problem was caused by a software upgrade that caused a conflict.

More serious however was this problem, which could have damaged the telescope beyond repair had it had been randomly pointed at the Sun during safe mode.

In entering safe mode on Sunday, however, the team discovered that the aperture door located at the top of the telescope failed to automatically close. This door is a safeguard designed to keep the Sun’s damaging light and heat out of the telescope’s interior, protecting its sensitive instruments and their surroundings. It serves as a safety net if Hubble accidently points in the direction of the Sun due to an error or hardware problem.

…The team has looked at spacecraft engineering data, run various tests, and verified that the door did indeed remain open despite the commands and power being sent to close it. Additional attempts to move the door by sending commands from the ground to its primary motor also failed to make the door move. However, the same commands sent from the ground to its backup motor did indicate movement, and that motor is now set as the primary motor. The team is looking at options to further reduce any associated risk.

It appears the primary motor that moves the door has failed. Fortunately there is a backup motor, but this is just one more item where the telescope has lost redundancy. We are very lucky that during safe mode the telescope didn’t end up pointing at the Sun, even for a very short time, for that would have ended Hubble’s operation for good. I suspect the safe mode software includes protections against that occurrence, but the possibility nonetheless existed.

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A proposal to rebuild Arecibo as a better radio telescope

9:47 am

Even as the National Science Foundation (NSF) proceeds with the disassembly of the destroyed Arecibo radio telescope in Puerto Rico, some astronomers are proposing that a new radio telescope be built in its place, with a new design that will not require the instrument platform floating above a single dish.

Here’s the idea as outlined in a white paper circulated by Roshi and his colleagues: The Next Generation Arecibo Telescope would pack hundreds, maybe even more than 1,000 smaller radio dishes into the same space now occupied by the single 305-meter dish. Those smaller antennas would combine forces to act like a single larger telescope (no suspended instrument platform required).

Ideally, those dishes would be on a single, tiltable platform to access more of the sky from the Arecibo site; it’s possible multiple platforms could do the same.

The revamped telescope would have twice the sky coverage of the legacy dish, 500 times the field of view in individual images, at least double the sensitivity, and five times the radar power.

The cost for this new radio telescope is presently estimated to be about half a billion. Considering that the NSF didn’t have the money to operate the old Arecibo telescope, which was why it wasn’t properly maintained and collapsed, I doubt it has the cash to build this replacement. Congress, which likes printing money it doesn’t have, might step in and fund it, but if so that will only add to the national debt that is certainly going to cause the bankruptcy of the nation at some point in the future, a point that is getting closer and closer with each new trillion that Congress nonchalantly spends, on almost a monthly schedule.

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