Tuesday, February 27, 2024

Thermal vacuum testing for the Europa Clipper

NASA (via YouTube):

We'll be back soon. The spacecraft is currently undergoing vacuum testing.

I was a huge fan of the livestream for building the Perseverance rover--I'm glad they've got another one running for Clipper. It's fun to check in on the progress of the build and try to guess what they're working on at any given moment. 


Scheduled to launch in October 2024 and arrive in the Jupiter system in 2030, NASA’s Europa Clipper mission will place a spacecraft in orbit around Jupiter to perform a detailed investigation of Europa.

This will maximize the scientific return from the lifetime of Europa Clipper, which is investigating the “habitability” of Europa. Habitability is a measure of whether Europa could support life and includes the presence of essential ingredients like liquid water, chemical building blocks and an energy source.

“Europa is considered one of the most likely sites in our solar system to potentially find life,” said SwRI Lead Scientist Dr. Kelly Miller.


Today is a big day for the Europa Clipper team. They'll be testing the craft's thermal pumping system, the last major addition to the spacecraft's vault, a thick-walled aluminum alloy box that holds the spacecraft's "brain": its electronics and computers.

"The thermal pump is the heart of the spacecraft," pumping fluid through tubing to control the craft's temperature, Barajas said. The daylong effort is hazardous because of the high pressure used to test the system with helium, a nonflammable gas.

"Planetary protection has evolved," Barajas said of the strict work requirements he has to follow every day. "No one wants to be the person responsible when extra-terrestrial life is finally found and it turns out to be something we brought there from earth."

"I think that's where the stress comes from, right? That we feel the pressure and the burden of building this vehicle that has been the life's work of some and years of work for many others."

I'll continue updating this thread with news of the Europa Clipper development. 


Friday, February 23, 2024

Second update to: Evidence of near-ambient superconductivity in a N-doped lutetium hydride

I've been posting occasional updates as I've followed this and other superconductor stories with great interest. This one took an interesting turn with a series of retractions from Nature.


RETRACTED ARTICLE: Room-temperature superconductivity in a carbonaceous sulfur hydride

The editors of Nature have been alerted to concerns regarding the manner in which the data in this paper have been processed and interpreted. Nature is working with the authors to investigate these concerns and establish what (if any) impact they will have on the paper’s results and conclusions. In the meantime, readers are advised to use caution when using results reported therein. 

This is their second retracted paper.

Nature News:

Nature has retracted a controversial paper claiming the discovery of a superconductor — a material that carries electrical currents with zero resistance — capable of operating at room temperature and relatively low pressure.

“They have expressed the view as researchers who contributed to the work that the published paper does not accurately reflect the provenance of the investigated materials, the experimental measurements undertaken and the data-processing protocols applied,” [the retraction report] says, adding that these co-authors “have concluded that these issues undermine the integrity of the published paper”.

“It is at this point hardly surprising that the team of Dias and Salamat has a third high-profile paper being retracted,” says Paul Canfield, a physicist at Iowa State University in Ames and at Ames National Laboratory. Many physicists had seen the Nature retraction as inevitable after the other two, and especially since The Wall Street Journal and Science reported in September that 8 of the 11 authors of the paper — including Salamat — had requested it in a letter to the journal.

One lab says it has partially reproduced Dias and Salamat’s results using a sample provided by the Rochester team. But many others, which tried creating their own samples and running tests, could not. And in the meantime, other causes for concern have arisen. An investigation launched by Physical Review Letters before it retracted its paper by Dias and Salamat found “apparent data fabrication”.


Facing a mutiny by his co-authors, Ranga Dias, the University of Rochester (U of R) physicist embroiled in controversy over his superconductivity research and allegations of scientific misconduct, is set to have a third paper retracted.

If the paper is retracted, it will follow retractions of two other superconducting claims from Dias’s teams: one last month from Physical Review Letters (PRL), and one in September 2022 of a different Nature paper.

In a 14 September email to the co-authors, Nature Senior Editor Tobias Rödel says a postpublication review revealed issues that are “mostly unaddressed.” Rödel added, “We are in absolute agreement with your request that the paper be retracted.”

Questions about the March paper’s results appeared online immediately after its publication. On 2 May, two researchers submitted an anonymous critique of the paper to Nature. These researchers disclosed their identities to Science: They are James Hamlin, a high-pressure experimentalist at the University of Florida, and Brad Ramshaw, an expert in superconductivity at Cornell University.

In their letter to Nature the co-authors allege they had raised concerns about the study prior to publication, but that Dias dismissed them. 

After seeing the postpublication review, the co-authors used their access to the raw data to corroborate Hamlin and Ramshaw’s concerns about the zero-resistance measurement. 

New York Times:

A prominent physics journal on Tuesday retracted a materials science paper that has garnered scrutiny.

The retracted paper did not involve superconductivity, but it added to accusations against Dr. Dias of research misconduct, including the fabrication and falsification of data. 

Nine of the 10 authors of the paper, which was published in Physical Review Letters, agreed to the retraction. Dr. Dias was the lone holdout, and he has maintained that the paper accurately portrays the research findings. However, he said on Tuesday that his collaborators, working in the laboratory of Ashkan Salamat, a professor of physics at the University of Nevada, Las Vegas, introduced errors when producing charts of the data using Adobe Illustrator, software not typically used to make scientific charts.

This took me pretty massively by surprise. I can only speak from my own personal experience, but nobody--I mean nobody--makes charts by hand anymore. We've had programmatic tools to ensure precision for literally decades. Most plots these days are done using scripts that access plotting libraries; for example, I make my plots in Python using matplotlib. I just can't understand what part of the process one would use Adobe Illustrator of all things for--I wish Dr. Dias had elaborated on this more. The problems identified were found in the background subtraction procedure and potentially claims of duplicated data; without commenting on the truth of these allegations, how could one "accidentally" do these things or something similar in Adobe Illustrator of all things? And why would this affect the raw data files that were shared with the investigators and coauthors, which ultimately were found to be flawed as well? 

Nature News:

As part of the investigation, co-author Ashkan Salamat, a physicist at the University of Nevada, Las Vegas, and a long-time collaborator of Dias, supplied what he claimed was raw data used to create figures in the PRL paper. But all four investigators found that the data Salamat provided did not match the figures in the paper.

Ignoring everything else, the raw data didn't match the figures. But Dr. Dias necessarily needs the figures to be correct if his superconductor is legitimate--the figures showed the proof. 

Science News:

A stunning claim of a room-temperature superconductor that grabbed headlines has fizzled. The paper was retracted November 7 from the journal Nature, making for a trio of high-profile retractions for physicist Ranga Dias of the University of Rochester.

The retraction is no surprise to the scientific community, many of whom had expressed hefty skepticism about Dias’ work, following the earlier retractions and many other researchers’ failures to reproduce Dias’ results. 

Compared to the previous retractions, “this is much more worrying,” Boeri says. “This is not just somebody who is doing some honest mistakes.”

Ranga Dias (via Twitter):

Meissner effect on N- doped Lutetium Hydride! 

[mic drop gif]

The Meissner effect is considered the definitive proof of superconductivity!

I look forward to the submission of that result. At the end of the day, everyone only benefits if Dr. Dias is correct and room-temperature superconductivity is achieved. 

Previously on this blog:

Neutron star discovered in center of Supernova 1987A


Editor summary: The nearby supernova SN 1987A was visible to the naked eye, and its evolution has been observed over the ensuing decades. The explosion is thought to have produced a neutron star or black hole, but none has been directly detected. Fransson et al. observed a remnant of SN 1987A using near- and mid-infrared integral field spectroscopy. They identified emission lines of ionized argon that appear only near the center of the remnant. Photoionization models show that the line ratios and velocities can be explained by ionizing radiation from a neutron star illuminating gas from the inner parts of the exploded star

Nature News:

Astronomers used the [JWST] to finally spot signs of an ultradense ‘neutron star’ lurking in the explosion’s core in a galaxy that orbits the Milky Way. Light from the explosion reached Earth 37 years ago this week, in a supernova that revolutionized modern astrophysics by providing an up-close look at how stars die.

JWST did not observe the neutron star directly, because it remains obscured behind a veil of dust from the explosion. But the telescope detected light coming from argon and sulfur atoms that had been ionized, or electrically charged, by radiation blazing from the long-sought neutron star.

Over the years, astronomers watched as rings of gas and dust expanded outwards from the site of the explosion, usually growing dimmer but sometimes brightening when various ejected materials collided.

One outcome of such a supernova is to leave behind a black hole. But early observations of SN 1987A, such as the wave of neutrinos, suggested that it should have given rise to a neutron star, which can be just 20 kilometres across but is so dense that a teaspoonful weighs millions of tonnes.


Using the James Webb Space Telescope (JWST), astronomers have ended a nearly decade-long game of celestial hide-and-seek after they discovered a neutron star in the wreckage of a stellar explosion.

"For a long time, we've been searching for evidence for a neutron star in the gas and dust of Supernova 1987A," Mike Barlow, an emeritus professor of physics and astronomy and part of the team behind this discovery, told Space.com. "Finally, we have the evidence that we've been seeking."

Barlow suggested that researchers may be able to distinguish between a naked neutron star and one clothed by a pulsar-wind nebula by making further infrared observations of the heart of Supernova 1987A with the JWST's NIRSpec instrument.

"We have a program which is gathering data now, which will be getting data with 3 or 4 times the resolution in the near-infrared," he concluded. "So by obtaining these new data, we may be able to distinguish the 2 models that have been proposed to explain the emission powered by a neutron star.


On the Astraveo podcast:

Astronomers spot new tiny moons around Neptune and Uranus

Carnegie Science:  

The Solar System has some new lunar members—the first new moon of Uranus discovered in more than 20 years, and likely the smallest, as well as two new moons of Neptune, one of which is the faintest moon ever discovered by ground-based telescopes.

“The three newly discovered moons are the faintest ever found around these two ice giant planets using ground-based telescopes,” explained Carnegie astronomer Scott S. Sheppard. “It took special image processing to reveal such faint objects.” 

Discovering all three of the new moons required taking dozens of five-minute exposures over three- or four-hour periods on a series of nights. These exposures were shifted by the apparent motion of each respective planet and added together to create one very deep image. Using this time intensive observing technique on some of the largest telescopes in the world allowed the survey images to go deeper than any previous observations near Uranus and Neptune.

Follow-up observations on the Magellan telescopes in October of 2021 and again in 2022 and November 2023 confirmed the brighter Neptunian moon as orbiting Neptune.


Astronomers have found three previously unknown moons in our solar system — two additional moons circling Neptune and one around Uranus.

The latest tally puts Neptune at 16 known moons and Uranus at 28.

One of Neptune’s new moons has the longest known orbital journey yet. It takes around 27 years for the small outer moon to complete one lap around Neptune.


Uranus' new moon, the first detected around the ice giant in over two decades and possibly the smallest of its ilk, is just 5 miles (8 kilometers) wide; it takes 680 days to complete one orbit around Uranus. In comparison, one Mars' moons named Deimos, considered to be among the tiniest known moons in our solar system, is 8 miles (13 km) wide. 

The discovery was made using observatories in Hawaii and Chile by Scott Sheppard, a staff scientist at Carnegie Science, in collaboration with Marina Brozovic and Bob Jacobson of NASA's Jet Propulsion Laboratory (JPL), David Tholen of the University of Hawaii, Chad Trujillo of Northern Arizona University and Patryk Sofia Lykawa of Kindai University.

One of the discovery images shows how insanely faint the moon is compared to Uranus itself (already a very dim object from Earth):

a black and white, blurry image with lots of white streaks. There is a white blob in the center-right. To the very left of thto which a yellow arrow is pointing.
The discovery image of the new Uranian moon S/2023 U1 using the Magellan telescope on November 4, 2023. Uranus is just off the field of view in the upper left, as seen by the increased scattered light. S/2023 U1 is the faint point of light in the center of the image. (Image credit: Scott Sheppard)

On the Astraveo podcast:

Thursday, January 4, 2024

Coronal mass ejection from colossal New Year's Eve solar flare will strike Earth today


The coronal mass ejection CME was hurled into space by an X-class solar flare that burst from the surface of the sun at 4:55 p.m. EST (2155 GMT) on Sunday (Dec. 31). It is the most powerful flare that has happened on the sun during the current solar cycle, solar cycle 25, which began in Dec. 2019. In fact, the flare that ended 2023 with a bang is the largest that has been observed since Sept. 10, 2017, according to the Space Weather Prediction Center of the National Oceanic And Atmospheric Administration (NOAA).

I'm always amused by these comparisons articles like to make. "Largest that has been observed since 2017". We're approaching solar maximum so the flares will be the largest in the cycle. The solar cycle is ~11 years so the last maximum was in the early 2010s, and the last minimum was in the late 2010s. "This solar flare at near maximum was bigger than the ones at the minimum" has substantially less punch.

Storms like this have the capability to cause weak fluctuations in power grids and could have minor impacts on satellite operations. In addition to this, G1 geomagnetic storms can give rise to striking auroras, beautiful light shows seen over Earth, usually at higher latitudes.

In 2003, during the last solar maximum — the peak of the sun's activity during the solar cycle 24  — an X45 flare was seen erupting from the sun, the most powerful solar flare ever measured. 

A powerful X-class flare like the one seen on New Year's Eve has the potential for long-lasting radiation storms, which can damage satellites, including GPS, and affect aircraft flying near the poles of Earth, even giving passengers on these flights small radiation doses. X flares also have the potential to cause worldwide blackouts, if conditions were just right.

The Hill:

In an update Sunday evening, NOAA’s Space Weather Prediction Center (SWPC) released an image of the flare, which appeared as a large, glowing spot on the sun. You can see that image below. 

Image reproduced from thehill.com. Original caption: An X5 solar flare detected by NOAA’s Space Weather Prediction Center on December 31, 2023. (NOAA SWPC; cropped)

At an X5, Sunday’s flare was much smaller than the flare recorded in 2003. It was, however, the strongest since September 2017, when an X8.2 flare was detected, according to the SWPC. This flare also supersedes an X2.8 solar flare reported in the same region of the sun on December 14. At the time, the SWPC reported that flare was “likely one of the largest solar radio events ever recorded.”

Possible effects:

The SWPC said those using high-frequency radio signals (like emergency managers) may notice a “temporary degradation or complete loss of signal on much of the sunlit side of Earth” as a result of Sunday’s solar flare.

Previously on this blog:


Wednesday, January 3, 2024

New ultra-short period binary discovered


Binary evolution theory predicts that the second common envelope (CE) ejection can produce low-mass (0.32-0.36 Msun) subdwarf B (sdB) stars inside ultrashort-orbital-period binary systems, as their helium cores are ignited under nondegenerate conditions.

Here we report the discovery of a 20.5-minute-orbital-period ellipsoidal binary, TMTS J052610.43+593445.1, in which the visible star is being tidally deformed by an invisible carbon-oxygen white dwarf (WD) companion. 


The orbital periods of such detached sdB binary systems can be as short as 20 minutes. However, to date only four binaries of this type with orbital periods below one hour have been found.

Now, a team of astronomers led by Jie Lin of the Tsinghua University in Beijing, China, reports the detection of a new sdB binary with an extremely short orbital period...they discovered a dozen such objects, and one of them, which received designation TMTS J052610.43+593445.1 (or J0526 for short) turned out to be an sdB binary with an orbital period of approximately 20.5 minutes.

BNN Breaking:

The white dwarf, although ten times smaller than the sun, has a mass of 0.735 solar masses and an effective temperature of 25,400 K. This binary system presents astronomers with a unique opportunity to study the physics and evolution of stars under extreme conditions.

In about 1.5 million years, the subdwarf will begin transferring mass to the white dwarf at an even shorter orbital period, leading to the formation of an AM CVn star through the helium-star channel. This process is pivotal for understanding binary evolution from the second common envelope ejection to the formation of AM CVn stars. The discovery of TMTS J052610.43+593445.1 could play a significant role in investigating these binary evolution paths.


Previously on this blog:

Tuesday, January 2, 2024

JWST Reveals a Surprisingly High Fraction of Galaxies Being Spiral-like


In this letter, we used James Webb Space Telescope (JWST) images from the Cosmic Evolution Early Release Science Survey to visually identify spiral galaxies with redshift 0.5≤z≤4 and stellar mass ≥1010M⊙. Out of 873 galaxies, 216 were found to have a spiral structure.

These fractions are higher than the fractions observed with the Hubble Space Telescope (HST). We even detect possible spiral-like features at redshifts z>3.

This fraction is surprisingly high and implies that the formation of spiral arms, as well as disks, was earlier in the universe. 


Of these galaxies, 216 were classified as spirals. The authors were careful to note that some may be merging galaxies that were misclassified, but even then 108 of the galaxies were unanimously classified as spirals by evaluators. When the team arranged them by redshift, they found that while the fraction of spirals decreased as you went further into the past, the fraction of spirals at redshifts above z = 3 was much higher than expected. When the team calibrated observations, they found about a fifth of galaxies at z = 3 are spiral galaxies. These very early galaxies would have had to become spirals less than two billion years after the Big Bang, meaning that there would have been little time for mergers and collisions to be the cause.

If spiral galaxies were more common in the early universe than expected, it could indicate that certain conditions or mechanisms favored the formation of spiral structures at that time. This is quite at odds with the current understanding of what structures were favored during these early epochs of the Universe's development.

Previously on this blog:

Thermal vacuum testing for the Europa Clipper

NASA (via YouTube ): We'll be back soon. The spacecraft is currently undergoing vacuum testing. I was a huge fan of the livestream for b...