The Food and Drug Administration on Friday approved two gene therapies to treat sickle cell disease, one of the which is the first CRISPR/Cas9-based treatment to win regulatory approval in the US.

The announcement is a landmark in the treatment of sickle cell disease, a devastating condition in which red blood cells deform into a sickle shape and clog up blood vessels. Sickle cell disease affects around 100,000 people in the US, most commonly African Americans. It leads to anemia, vaso-occlusive events and crises (painful episodes in which small blockages starve tissue of oxygen), strokes, progressive and irreversible organ damage, decreased quality of life, and early death.

Until today, treatments have been limited. A bone marrow transplant from a genetically matched sibling can cure the condition more than 90 percent of the time, but only around 20 percent of people with the disease have such a genetically matched sibling donor. There are also multiple drugs available and supportive care, but these mainly reduce the severity of the disease. The new gene therapy treatments, on the other hand, have shown to be highly effective at preventing vaso-occlusive events and crises.

"Sickle cell disease is a rare, debilitating and life-threatening blood disorder with significant unmet need, and we are excited to advance the field, especially for individuals whose lives have been severely disrupted by the disease, by approving two cell-based gene therapies today," said Nicole Verdun, director of the Office of Therapeutic Products within the FDA’s Center for Biologics Evaluation and Research, said in the FDA's announcement.

To understand how the gene therapies work, it's useful to understand what causes sickle cell disease. The central problem is with adult hemoglobin, the iron-containing protein in red blood cells that transports oxygen from the lungs to the rest of the body. In patients with sickle cell disease, there's a single, small mutation in the gene that encodes hemoglobin. The mutation is a switch of a single nucleotide, or base, (often represented by letters A, C, T, and G). The switch of an A to a T in the genetic code for hemoglobin results in a hemoglobin protein with a valine instead of a glutamic acid at the sixth amino acid position. This transforms normal adult hemoglobin (HbA) to sickle hemoglobin (HbS). In red blood cells, when HbS loses the oxygen it was carrying, it polymerizes with itself, forming strand-like structures that deform the cell.

Effective edits

The CRISPR/Cas9 therapy approved today, called Casgevy, prevents this deformation by essentially turning on the production of another type of hemoglobin encoded in our genetic blueprints—fetal hemoglobin (HbF). HbF is optimized for pregnancy, transferring oxygen from maternal blood to fetal tissue, and the gene that encodes it is shut off shortly after birth as the body transitions to HbA. About six months after birth, HbF usually makes up just 1 percent to 2 percent of hemoglobin in the body.

But, HbF can effectively treat sickle cell disease—the hemoglobin transports oxygen just fine in adults, and it doesn't polymerize. Moreover, when it's mixed with HbS, it gets in the way of the mutated protein polymerizing with itself, preventing it from forming structures that deform red blood cells.

Casgevy turns on HbF with the CRISPR/Cas9 system, a gene-editing system initially swiped from bacteria that snips DNA using an enzyme (a nuclease) called Cas9. Cas9 can be targeted to specific stretches of DNA using a short RNA guide sequence. In Casgevy, the CRISPR/Cas9 system is targeted to snip a gene encoding a protein called BCL11A, which controls other genes, aka a transcription factor. The BCL11A transcription factor is the protein responsible for shutting off the gene for HbF shortly after birth as the body transitions to the adult version. With the CRISPR/Cas9 snip, BCL11A is shut off, and HbF production can resume.

For patients being treated, this process involves first harvesting their bone marrow stem cells, which then get CRISPR-ed in a specialized lab. Meanwhile, the patients receive chemotherapy to kill bone marrow cells to make way for the gene-edited cells that are then put back in. Of 31 patients treated with Cagevy and followed for at least 24 months, 29 (93.5 percent) went at least 12 consecutive months without a vaso-occlusive crisis.

The other gene therapy approved by the FDA today is Lyfgenia, which used a Lentiviral vector to insert genes into the human genome. In this case, the system delivers the genetic code for a modified type of hemoglobin that is designed to be anti-sickling, called HbA^T87Q. Among 32 patients treated with Lyfgenia, 28 (88 percent) were free of vaso-occlusive events for between six to 18 months after treatment.

Both gene therapies are approved for patients ages 12 years and up.

The Hubble Space Telescope resumed science observations on Friday after ground teams spent most of the last three weeks assessing the performance of a finicky gyroscope, NASA said.

The troublesome gyroscope is a critical part of the observatory's pointing system. Hubble's gyros measure how fast the spacecraft is turning, helping the telescope aim its aperture toward distant cosmic wonders.

Hubble still provides valuable scientific data for astronomers nearly 34 years since its launch aboard NASA's Space Shuttle Discovery in 1990. Five more shuttle servicing missions repaired Hubble, upgraded its science instruments, and replaced hardware degraded from long-term use in space. Among other tasks, astronauts on the last of the shuttle repair flights in 2009 installed six new gyroscopes on Hubble.

Moving parts sometimes break

The gyros have long been one of the parts of Hubble that require the most upkeep. A wheel inside each gyro spins at a constant rate of 19,200 revolutions per minute, and the wheel is, in turn, sealed inside a cylinder suspended in a thick fluid, according to NASA. Electronics within each gyro detect very small movements of the axis of the wheel, which supply Hubble's central computer with information about the spacecraft's turn rate. Hair-thin wires route signals from the gyroscopes, and these wires can degrade over time.

Three of the six gyros installed on Hubble in 2009 have failed, and three others remain operational. The three still-functioning gyros are based on a newer design for longer life, but one of these units has shown signs of wear in the last few months. This gyroscope, designated Gyro 3, has always exhibited "consistent noisy behavior," said Pat Crouse, Hubble project manager at NASA's Goddard Space Flight Center.

Hubble typically needs three gyros to operate normally, so ground controllers shut down Gyro 3 for roughly seven years until Hubble needed it in 2018, when another gyroscope failed, leaving only three of the devices still working.

"Back in August, we saw issues," Crouse told Ars this week. "It would sort of sporadically output some rate information that was not consistent with the observed spacecraft body rates, but it was short-lived, and we were characterizing what that performance was like and how much we could tolerate."

The gyro's performance worsened in November when it fed Hubble's control system erroneous data. The gyroscope sensed that the spacecraft was changing its orientation when it really wasn't moving. "That, then, contributed to an error in attitude that was kind of causing a little bit of drift," Crouse said.

Automated software on Hubble detected the errors and put the spacecraft into "safe mode" two times last month. Hubble quickly resumed science observations each time but then went into safe mode again on November 23. Hubble managers took some extra time to gather data on the gyro's health. Engineers commanded Hubble to move back and forth, and the suspect gyro consistently seemed to work well.

Recognizing that the gyros are prone to failure, engineers devised a new way for Hubble to keep delivering science data even with one operating gyroscope. In this one-gyro mode, Hubble's control system would receive inputs from the single gyroscope in combination with magnetometers, Sun sensors, and star trackers. Most of Hubble's science portfolio would not be affected in a one-gyro mode, but the observatory could have limitations following some faster-moving targets, such as planets, asteroids, or comets in the inner part of the Solar System.

Hubble uses spinning reaction wheels to torque the spacecraft in large movements from one direction to another. The spacecraft doesn't have any thrusters to control its orientation or adjust its orbit. There are three fine guidance sensors to maintain a lock on guide stars, keeping Hubble stable during scientific observations. Crouse said Hubble's ground team is also keeping a close eye on these sensors.

One of the fine guidance sensors has shown signs of degraded performance in the last two years, he said. A buildup of debris or lubrication along a bearing appears to be the source of some resistance in the sensor, occasionally causing it to stall.

Another servicing mission?

While Hubble doesn't match the imaging power and resolution offered by the newer James Webb Space Telescope, the aging observatory still occupies a unique role among NASA's fleet science missions. Hubble is sensitive to visible and ultraviolet light, while Webb's sensors are tuned to detect infrared light.

NASA wants to keep Hubble going as long as possible. Even if Hubble's sensors and instruments are still working, aerodynamic drag will eventually bring the telescope back into the atmosphere because the spacecraft doesn't have any rocket engines. Each of the space shuttle servicing missions boost Hubble into a higher orbit to counteract the drag.

Hubble is currently flying at an altitude of around 320 miles (520 kilometers). Current predictions suggest Hubble would reenter the atmosphere in the mid-2030s, but this depends on the conditions of the upper atmosphere, which change with fluctuations in solar activity.

Last year, SpaceX and NASA announced a feasibility study to determine whether it might be possible for a Dragon spacecraft to link up with Hubble and reboost the observatory, extending its orbital lifetime. This six-month study, which was concluded earlier this year, was also expected to look at ways for astronauts on the Dragon capsule to potentially service Hubble. If a servicing mission is deemed possible, swapping out gyros would surely be at the top of NASA's priority list.

NASA and SpaceX have not released the results of the feasibility study. Last December, NASA also released a request for information from other US companies to propose their own commercial solutions for boosting Hubble's orbit. The agency received eight responses to this solicitation, not including the separate SpaceX feasibility study. In the end, NASA may decide not to move forward with a commercial servicing mission to Hubble.

Alise Fisher, a NASA spokesperson, told Ars the agency doesn't have a projected timeframe for completing its review of the Hubble reboost studies. "We will continue internal evaluations early next year."

Welcome to Edition 6.22 of the Rocket Report! We're nearing the end of 2023, and it's been an incredible year for rocket debuts. Early in the year we saw small lift vehicles from Relativity Space and ABL, and in the spring Japan's H3 and SpaceX's Starship rocket. There's one big one left: United Launch Alliance's Vulcan booster. That will be a nice stocking stuffer to end the year on Christmas Eve.

As always, we welcome reader submissions, and if you don't want to miss an issue, please subscribe using the box below (the form will not appear on AMP-enabled versions of the site). Each report will include information on small-, medium-, and heavy-lift rockets as well as a quick look ahead at the next three launches on the calendar.

Vega has a missing parts problem. In unhappy news for Italian rocket-maker Avio, two of the four propellant tanks on the fourth stage of the Vega rocket—the upper stage, which is powered by dimethylhydrazine and nitrogen tetroxide fuel—went missing earlier this year. Now, it seems that the propellant tanks have been found. However, Ars reports, the tanks were recovered in a dismal state, crushed alongside metal scraps in a landfill. This is a rather big problem for Avio, as this was to be the final Vega rocket launched, and the production lines are now closed for this hardware.

Two not great options ... This Vega rocket is due to launch the 1,250-kg BIOMASS satellite for the European Space Agency, a mission that will employ a P-band synthetic aperture radar to assess the health of forests on Earth and determine how they are changing. The satellite is valued at more than $200 million. Officials are working on two options. The first involves using old propellant tanks that were built for qualification tests of the Avio rocket more than a decade ago. Another option is to modify the upper stage that is used by the new Vega C rocket. While there are some commonalities between the Vega and Vega C upper stages, there are differences, and the new AVUM+ upper stage was not intended to fly on the original Vega rocket. (submitted by Ken the Bin and EllPeaTea)

Stratolaunch progressing toward Talon A launches. On Sunday, Stratolaunch completed the first captive carry flight of a powered Talon A hypersonic vehicle under the wing of its larger carrier aircraft, Roc. Stratolaunch is working for the US military on a target that will mimic hypersonic threats to support the development of new defensive capabilities, which is expected to be a Talon-A derivative or at least utilize some of the same technology, The Drive reports.

A powered flight could be on the way ... This was the 12th flight for the Roc launch platform, and it saw the Talon-A fueled. The flight lasted three hours and 22 minutes. It was, according to Stratolaunch, “a significant step forward in the company’s near-term goal of completing a powered flight with the Talon-A vehicle.” Talon-A is expected to be able to reach speeds of at least Mach 6. The vehicle is 28 feet long and has a wingspan of just over 11 feet. A powered launch may be up next, pending a data review. (submitted by Ken the Bin)

South Korea tests solid-fuel rocket. South Korea on Monday successfully conducted a flight of a solid-fuel rocket carrying a satellite over the sea near Jeju Island amid a growing space race with neighboring North Korea, the defense ministry said. It was the third successful test of the rocket's technology after two others in March and December 2022, Reuters reports.

Improving reconnaissance operations ... Hanwha Systems said the satellite, which will be used for civilian purposes, including environmental monitoring, had successfully sent signals to the ground control center. The ministry hailed the launch as achieving a milestone just after Pyongyang launched its first military spy satellite, which the United States and its allies have condemned for using missile technology contravening a UN security resolution. South Korea's successful launch will enable the country to accelerate its surveillance and reconnaissance capabilities, the ministry said. (submitted by wesley96, Ken the Bin, and tsunam)

Iran says it wants a crew launch this decade. On Wednesday, Iran launched a 1,100-pound (500-kg) capsule to an altitude of 80 miles (130 km) on one of its Salman solid-propellant rockets, Space.com reports. Al Jazeera reports there were unknown animals aboard, but there is no official confirmation of what they might have been. The animals, apparently, were not recovered. Regardless of any animal occupants, the Iranian Space Agency says the capsule will help the nation put its own astronauts into space.

Those are some big plans ... This launch of an "indigenous bio-capsule" was part of Iran's ambition to launch astronauts into orbit by the end of 2029, according to a senior official. "In line with the implementation of the ten-year document of the country's space industry, the 'Life in Space' program has been revived and soon, God willing, the suborbital tests of the new generation 'bio-capsule' will be completely Iranian," Iranian Communication Minister Eisa Zarepour said. If Iran launches humans with indigenous technology by the year 2029, I'll retire on the spot. (submitted by Ken the Bin)

Amazon to launch satellites on a Falcon 9. In a real wow moment for the space industry, Amazon announced last Friday that it had purchased three Falcon 9 rocket launches from SpaceX beginning in mid-2025 to help deploy the retail giant's network of Kuiper Internet satellites. Amazon said the SpaceX launches would provide "additional capacity" to "supplement existing launch contracts to support Project Kuiper’s satellite deployment schedule," Ars reports. SpaceX has its broadband satellite fleet, with more than 5,100 Starlink spacecraft currently in orbit, making it a competitor with Amazon.

A lot needs to go right ... Last year, Amazon bought up most of the Western world's excess launch capacity from everyone but SpaceX, securing 68 rocket flights from United Launch Alliance, Arianespace, and Blue Origin to deploy thousands of satellites for the Kuiper broadband network. Amazon previously contracted with ULA for nine Atlas V launches to support the initial series of Kuiper launches. Assuming all these rockets fly successfully on their current schedules, ULA, Arianespace, and Blue Origin will need to rapidly ramp up their launch rates to meet Amazon's demand and string together a series of successful flights. It's not uncommon for new rockets to fail on early test flights.

SpaceX plans to dramatically increase Vandy launches. Nate Janzen, manager of launch pad systems and operations for SpaceX at Vandenberg Space Force Base, spoke last week during the 10th annual celebration and Future Forum for the Economic Alliance Foundation, or EconAlliance, at the Santa Maria Country Club. "We’re really ramping up Vandenberg to rates that we’ve never seen before and the area hasn’t seen before," Janzen said, according to Noozhawk.

Also taking another look at booster longevity ... From one launch four years ago to three the next year and 12 the following year, SpaceX expects about 30 liftoffs by the end of this year. For 2024, the rate could jump to 50, then rocket to 100 in 2025. "Next year, we’ll be launching about once a week, but the plan, in about two years, is about every three to four days," Janzen said. Additionally, next year, SpaceX will re-evaluate and conduct analysis with an eye toward certifying the first-stage boosters for 25 to 30 flights, he said.

Next Starship flight could test prop transfer. SpaceX and NASA could take a tentative step toward orbital refueling on the next test flight of Starship, but the US space agency says officials haven't made a final decision on when to begin demonstrating cryogenic propellant transfer capabilities that are necessary to return astronauts to the Moon, Ars reports. NASA is keen on demonstrating orbital refueling technology, an advancement that could lead to propellant depots in space to feed rockets heading to distant destinations beyond Earth orbit.

A worthy first step ... This test would involve transferring super-cold propellant from one tank to another inside a Starship spacecraft. It's a precursor to future, more complex demonstrations involving two giant Starships docked together in Earth orbit. Then SpaceX will be ready to send a Starship toward the Moon for a test landing without astronauts onboard. Once that is successful, NASA will clear Starship for a crew landing on the agency's Artemis III mission, marking the astronauts' return to the lunar surface for the first time since 1972. (submitted by Ken the Bin)

Space shuttle stack taking shape. The work to stand up two rockets for the launchpad-like exhibit of NASA's retired space shuttle Endeavour has been capped—literally and figuratively—with the addition of two nose cones on solid rocket boosters, Space.com reports. The work is part of an initiative by the California Science Center to display Endeavour in its vertically stacked configuration, complete with solid rocket boosters and NASA's last-remaining, built-for-flight space shuttle external tank (ET-94).

Stacked for the final time ... The SRBs going on exhibit with Endeavour were assembled from all flight-worthy or previously launched parts donated by Northrop Grumman and NASA. They were the first major components to be taken vertical as part of the science center's "Go for Stack" campaign. This will be an awesome exhibit to visit when completed in a couple of years. (submitted by Tfargo04)

ESA eyeing development of a Raptor-class engine. The European Space Agency has published a call for ideas aimed at beginning the development of a high-thrust rocket engine that could be utilized aboard future heavy-lift launcher vehicles, European Spaceflight reports. Currently, the space agency is working toward launching its Vulcain 2.1 and Prometheus liquid rocket engines for the first time. While Vulcain 2.1 will serve as the primary engine for the Ariane 6 core stage, Prometheus is being developed to equip the next generation of European launch vehicles.

Only in the study phase for now ... Prometheus is, however, only capable of producing 100 tonnes of thrust, a capability that ESA appears to feel is inadequate for its as yet undefined future heavy-lift launch vehicles. As a result, the agency plans to launch its Very High Thrust Propulsion Building Block for Increased Performance Launchers project. The aim of the project is to develop an engine capable of generating at least 250 tonnes of thrust, which is in the same ballpark as the SpaceX Raptor engine that powers the company’s Starship launch vehicle. The project is, however, only in its very earliest study phases. (submitted by EllPeaTea and Ken the Bin)

BE-4 manager alleges wrongful termination. The former program manager of Blue Origin’s BE-4 rocket engines has filed a lawsuit against the company alleging whistleblower retaliation after he spoke up about safety issues, TechCrunch reports. The complaint was filed in the Los Angeles County Superior Court. It includes a detailed narrative about program manager Craig Stoker’s efforts over seven months to escalate his concerns about safety and a hostile work environment at Blue Origin.

An explosive CEO ... Allegedly, Stoker told two VPs in May 2022 that then-CEO Bob Smith’s behavior caused employees “to frequently violate safety procedures and processes in order to meet unreasonable deadlines.” Smith would “explode” when issues would arise, generating a hostile work environment, the complaint says. Ultimately, after an internal investigation, Blue Origin Human Resources concluded that Smith did not create a hostile work environment, nor violate any company policies. Stoker was terminated on October 7, seven months after he raised his first safety concern. Smith has since left Blue Origin. (submitted by terkans)

Next three launches

December 8: Falcon 9 | Starlink 7-8 | Vandenberg Space Force Base, Calif. | 08:00 UTC

December 8: Zhuque-2 | Flight Three | Jiuquan Satellite Launch Center, China | 24:40 UTC

December 10: Long March 2D | Unknown Payload | Xichang Satellite Launch Center, China | 01:58 UTC

Good morning. It's December 8, and today's photo comes from the floor of the Grand Canyon. The photographer, Mitchell Yee, admits that this is not the best shot one might capture from this remote location, but there's a reason—he shot it on his iPhone in August.

"While it's a fairly ordinary photo, what was amazing to me was the level of quality of cell phone photography," he told me. "Normally, I'd haul out my big Nikon but since we were hiking down to the bottom of the canyon to meet our dories, weight was constrained. So I skipped the extra 15–20 pounds of camera, lens(es), and tripod and instead enjoyed the 9-mile hike with my 18-pound pack. Of course, this shot could have been much improved with a 'real' camera on a tripod. But there I was, flat on my back on a sand berm, with the best camera I had at that moment, my iPhone 13 mini, and I still made the shot I wanted."

Dories, I'm pretty sure, are boats. But I'm kind of in "Afraid to Ask" Andy territory with that one.

In any case, I thought the photo was lovely, and I appreciate Mitchell sharing it.

Source: Mitchell Yee

While it may be the reason behind tires skidding, pipes bursting, and closed roads making traffic a nightmare, ice doesn’t always form as easily as it seems. It often gets an assist from proteins made by fungi. 

Never mind the common thinking that ice forms at 0° C (32° F). Though this is water’s freezing point, pure water will only freeze when temperatures plummet as low as minus 46° C (minus 50.8° F). So why does it usually freeze at zero anyway? Organisms such as bacteria, insects, and fungi produce proteins known as ice nucleators (non-protein nucleators can also be of abiotic origin). These proteins can kick-start the formation, or nucleation, of ice at higher temperatures than pure water would freeze at.

While the exact reason fungi make these proteins remains unknown, researchers Valeria Molinero of the University of Utah and Konrad Meister of Boise State University led a study that has revealed more about how fungal ice nucleators can both promote and hold back ice formation more efficiently than those of many other life-forms.

Getting to the nucleus

Organisms capable of producing ice nucleators belong to different biological kingdoms but are thought to have evolved the same ability independently—a phenomenon known as convergent evolution. Fungal ice nucleators had been something of an enigma until Molinero, Meister, and their team studied the nucleators produced by the fungus Fusarium acuminatum.

“We find ice-binding and ice-shaping activity of Fusarium [ice nucleators], suggesting a potential connection between ice growth and inhibition,” the scientists said in a study recently published in PNAS.

Ice nucleators help freeze water by fast-forwarding nucleation, which is the process by which water molecules initiate the formation of ice crystals. Forming a crystal means molecules of H₂O must align themselves in specific orientations to form a rigid lattice structure. This starts as a small group of latticed molecules, a “nucleus” in liquid water. If this nucleus is large enough, more water molecules will aggregate on it until an ice crystal forms.

This is difficult for pure water to do on its own because the motion of its molecules makes it difficult to form a nucleus. Ice nucleator proteins help water molecules aggregate into a nucleus. Some bacterial nucleators are so effective that the bacteria that produce them are used to make snow at ski resorts. 

Frozen in mystery

Fusarium nucleators are also highly efficient and effective. Meister and Molinero’s team found that these fungal proteins are much smaller than many of those synthesized by bacteria and other organisms, and large numbers of them join together into complex structures that help ice nucleate. Even when the levels of Fusarium proteins were reduced in the lab, they could still trigger the nucleation process.

The scientists have a hypothesis as to why Fusarium and some other organisms evolved such small molecules that aggregate so efficiently: “We expect that the energetic benefit for the organism in producing smaller proteins, rather than a single large one, contributes to the success and adoption of [this] strategy across species that are not evolutionary-related,” they said in the same study.

Another question—one where the answer has not crystallized yet—is why fungi use ice nucleators. Whether they are meant to promote ice formation or whether it is an incidental side effect of another benefit they provide to the fungus still needs to be researched.

But creatures like frogs might give us a clue. Many frog species have a natural antifreeze that keeps them alive while they fall into a state of torpor during the colder months. It is not uncommon for them to end up covered in ice, but ice nucleators produced in their cells help them control where ice forms, keeping them alive (along with an antifreeze made of urea and glucose). Some species also ingest bacteria that help with the process. Could ice nucleators in fungi be part of a similar antifreeze system? At this point, nobody knows.

As more continues to be demystified about biological and abiotic ice nucleators, they could eventually be used for more efficient methods of freezing food, making snow, creating clouds, and possibly the cryogenic freezing of human cells, which was recently successful. The future is frozen.

PNAS, 2023.  DOI: 10.1073/pnas.2303243120

We are not alone—at least as a galaxy. About 50 dwarf galaxies surround the Milky Way. But when its intense gravity inevitably draws them to venture too close, they will probably be annihilated. It’s happened before.

Though scientists used to think that all those dwarf galaxies orbiting the Milky Way were going to stick around for tens of billions of years, that might not be the case. “Most dwarf galaxies are star systems that arrived late in the Milky Way… in sharp contrast with a long-term satellite hypothesis,” an international team of researchers said in a study recently published in Monthly Notices of the Royal Astronomical Society.

Based on data from the European Space Agency’s Gaia mission, this study has found that many dwarf galaxies that were orbiting the Milky Way only a few billion years ago have ended up destroyed after being pulled in by our much more massive galaxy. It is possible dark matter has something to do with this.

The researchers used Gaia data to date objects within the Milky Way that originated in smaller galaxies that had previously been swallowed. By identifying galactic remnants, they determined that most dwarf galaxy remnants within the Milky Way only entered it within the last 3 billion years or so. When these galaxies crashed into our own, there was so much turbulence that they lost their gas, and their structures were drastically changed.

A matter of dark matter

The destruction experienced by the dwarf galaxies that entered the Milky Way brings the amount of dark matter in these galaxies into question. If they were rich in dark matter, the mass and gravity of that dark matter would have helped keep most objects in their orbits even in the face of some disruption. In other words, the dwarf galaxy would remain a coherent object even after being incorporated into the Milky Way.

That’s not the case, which probably means those galaxies were lacking in dark matter. If dwarf galaxies currently orbiting the Milky Way are also dark-matter deficient, they could also end up being eaten alive in the future.

The finding raises an additional question. Physics indicates that the dwarf galaxies orbiting the Milky Way should be rich in dark matter. But if there was as much dark matter in these galaxies as predicted by classical physics, it would probably hold them together strongly enough so they would make it past the halo mostly intact.

Until recently, galaxies that the Milky Way has absorbed were thought to have orbited for many billions of years longer than they actually had. This is because the previous thinking was that these galaxies were full of dark matter. That dark matter would have protected these galaxies as the Milky Way’s enormous gravitational pull threatened to tear them apart.

Those galaxies that have already been absorbed by the Milky Way predictably have less orbital energy than galaxies still outside the Milky Way. Orbital energy is the gravitational potential energy and kinetic energy of an object in relation to the same qualities of the object it orbits. Galaxies with the least orbital energy are thought to have merged farther back in time since their stars are presently scattered farther from each other.

For example, the dwarf galaxy Sagittarius entered the Milky Way around 5 or 6 billion years ago. It was an elliptical galaxy, but its present remains are not very structured, and its objects have widely varying velocities. This disruption is consistent with a relative scarcity of dark matter.

Trying to shed light

Dark matter is invisible and undetectable—its presence can only be inferred. So estimating the dark matter content of dwarf galaxies that have been absorbed by the Milky Way is extremely difficult, because there is no way to get a read on their dynamical mass, which is measured by the movement of objects in a galaxy.

If objects in these galaxies had stayed in the same orbits they were in before absorption, it would be possible to infer dark matter content. The problem is that the velocities and orbits of the stars in absorbed galaxies have been altered by interactions with Milky Way objects. Therefore, there is no way to make this estimate given the chaos of a galaxy that has been disrupted.

The stars in dwarf galaxies that entered the Milky Way a few billion years ago have been flung far from their galactic cores. Almost nothing is in order anymore. While the researchers think there may be some other way to at least get an idea of how much dark matter may have been in these galaxies, for now, we are in the dark.

Monthly Notices of the Royal Astronomical Society, 2024. DOI:  10.1093/mnras/stad2922

Good morning. It's December 7, and today's photo takes us toward the iconic Cassiopeia constellation. One of the most colourful features in this constellation is the Heart Nebula, which is also known as the Running Dog Nebula because, well, I'll let you figure that out for yourself.

The nebula itself is located about 7,500 light-years from Earth. It is also rather large, spanning 2° of the night sky, or an area larger than that covered by the Moon. The Heart Nebula's shape is driven by supermassive stars in its core, with the blue colours produced by ionized oxygen and sulfur.

The image comes courtesy of Paul Macklin, who captured 72 hours of imaging data from his backyard in Indiana before processing it. The photograph combines four separate mosaics: Sulfur II (deep red), Hydrogen-alpha (red-orange), Oxygen III (blues), and Hydrogen-beta (deep blue). Clearly, it was produced with love.

Source: Paul Macklin

There's widespread agreement that most useful quantum computing will have to wait for the development of error-corrected qubits. Error correction involves distributing a bit of quantum information—termed a logical qubit—among a small collection of hardware qubits. The disagreements mostly focus on how best to implement it and how long it will take.

A key step toward that future is described in a paper released in Nature today. A large team of researchers, primarily based at Harvard University, have now demonstrated the ability to perform multiple operations on as many as 48 logical qubits. The work shows that the system, based on hardware developed by the company QuEra, can correctly identify the occurrence of errors, and this can significantly improve the results of calculations.

Yuval Boger, QuEra's chief marketing officer, told Ars: "We feel it is a very significant milestone on the path to where we all want to be, which is large-scale, fault-tolerant quantum computers.

Catching and fixing errors

Complex quantum algorithms can require hours of maintaining and manipulating quantum information, and existing hardware qubits aren't likely to ever reach the point where they're capable of handling that without causing errors. The generally accepted solution to this is to work with error-correcting logical qubits instead. These involve distributing individual qubits among a collection of hardware qubits so that an error in one of these qubits doesn't completely destroy the information.

Additional qubits can add error correction to these logical qubits. These are linked to the hardware qubits that hold the logical qubits, allowing their state to be monitored in a way that will identify when errors have occurred. Manipulation of these additional qubits can restore them to the state that was lost when the error happened.

In theory, this error correction can allow the hardware to hold quantum states for far longer than the individual hardware qubits are capable of.

The trade-off is significantly increased complexity and qubit counts. The latter should be obvious—if each logical qubit requires a dozen qubits, then you need a lot more hardware qubits to run any algorithm. Full error correction would also require repeated measurements to identify when errors have occurred, identify the type of error, and perform the necessary corrections. And all of that would have to happen while the logical qubits are also being used for running those algorithms.

There's also the actual practicalities of getting any of this to work. It's really easy (by a very relaxed definition of "easy") to understand how to perform operations on pairs of hardware qubits. It's far more difficult to understand how to do them when any individual hardware qubit holds, at most, only a fraction of a logical qubit. Adding to the complexity is that there are a variety of potential error-correction schemes, and we're still figuring out their trade-offs in terms of robustness, convenience, and qubit use.

That's not to say that there hasn't been progress. Error-corrected qubits have been demonstrated, and they do maintain quantum information better than the hardware qubits that host them. And, in a few cases, individual quantum operations (termed gates) have been demonstrated using pairs of logical qubits. And two companies (Atom Computing and IBM) have been ramping up qubit counts to provide enough hardware to host lots of logical qubits.

Enter QuEra

Like Atom Computing, QuEra's hardware uses neutral atoms, which have several advantages. Quantum information gets stored in the nuclear spin of individual atoms, which is relatively stable in terms of maintaining quantum information. And, since every atom of a given isotope is equivalent, there's no device-to-device variation as there is in qubits based on superconducting hardware. Individual atoms can be addressed with lasers instead of needing wiring, and the atoms can be moved around, potentially allowing any qubit to be linked to any other.

QuEra's current generation of hardware supports up to 280 atom-based qubits. For this to work, those atoms were moved around among several functional regions. One is simply storage, where qubits live when they're not being manipulated or measured. This holds both any logical qubits in use and a pool of unused qubits that can be mobilized over the course of executing an algorithm. There's also an "entanglement zone" where those manipulations take place and a readout zone where the state of individual qubits can be measured without disturbing qubits elsewhere in the hardware.

Boger drew a comparison between this architecture and traditional computers, telling Ars that "the advantage of this architecture is you could, for instance, double your memory without changing your CPU." In terms of the actual hardware, QuEra could potentially alter the hardware that holds the atoms in memory without changing the system it uses for readout.

Several aspects of neutral atom qubits make performing operations on logical qubits somewhat easier. For example, performing an operation on a logical qubit can be as simple as moving all the atoms that comprise it into the entanglement zone and shining a single laser on them, essentially performing the same operation on all of the logical qubit's component atoms at once. A similar thing can be done with two logical qubits to perform a gate operation on them.

In addition, the separate measurement zone allows the qubits used for error correction to be moved and measured while algorithms are in process without disrupting any of the other components of the logical qubit. Alternatively, in some of the experiments here, these qubits are held in memory until after an algorithm is complete. At this point, they can be measured and the results discarded if there's an indication that an error took place.

Working logically

Even the process of initializing logical qubits showed their potential benefit. By selecting instances where later measurements showed no indication of errors, the fidelity of the initialization reached over 99.9 percent, well above the rate of success when individual hardware qubits are initialized (99.3 percent).

In addition, the research team tested various error-correction schemes that used different numbers of qubits. As the number of hardware qubits in the logical qubit went up, the overall error rate dropped.

This isn't full error correction. "What is happening in the paper is that the errors are corrected only after the calculation is done," Boger said. "So, what we have not demonstrated yet is mid-circuit correction, where during the calculation, we measure... an indication of whether there's an error, correct it, and move forward."

The researchers then performed a variety of algorithms using the logical qubits. In one case, they could use classical computers to estimate the probabilities of different outcomes of a series of manipulations; that could then be compared with actually performing the manipulations. Without any sort of error detection, there was a fair bit of noise in the outcome of the experiment. But as the researchers got more stringent about rejecting measurements with indications of errors, the results got progressively cleaner. One measurement of accuracy rose from 0.16 to 0.62.

In a separate set of experiments, the researchers tested algorithms on collections of logical qubits that ranged in size from three up to 48. In all these cases, the logical qubits outperformed both physical qubits and logical qubits where no measures were taken to limit the impact of errors, even in algorithms that involved as many as 270 gate operations. In the operations on 48 logical qubits, the difference in performance was a factor of 10.

The researchers also estimate that adding just three more operations would be enough to make the system intractable to simulation using classical computers.

What’s next?

Boger told Ars that QuEra plans to provide a road map for its future developments in January. But it's possible to infer a fair amount about what still needs to be done. For starters, as Boger said, this isn't full error correction done while calculations are in progress, and QuEra is working on that. In addition, the algorithms used in these tests aren't useful in the sense that no commercial customer would pay to run them. The logical qubit count will have to be brought up before that's going to be possible.

The other reason to bring the qubit count up is that, as this work demonstrates, having more qubits to use for a logical qubit drops the error rate. If each logical qubit required 10 hardware qubits, the current QuEra hardware can only host 22 of them at once. Obviously, to run these demonstrations with 48 qubits means that fewer than 10 were used, so more errors ended up uncaught than might be possible on a larger machine.

That said, QuEra states in its paper that optimized control and boosted laser power should allow this architecture to reach 10,000 physical qubits, so there should be quite a bit of headroom there. And, since all control operations are handled using lasers, it should be possible to use photonic links to bridge separate pieces of hardware. Boger also mentioned that boosting the readout system should boost performance by cutting down the time available for errors to take place.

But the value of all of that potential progress is predicated on the belief that we'd ultimately be able to perform a complex series of manipulations on logical qubits and correct any errors in real time. The first half of that has now moved out of the realm of belief and into the list of technologies that have been demonstrated.

Nature, 2023. DOI: 10.1038/s41586-023-06927-3  (About DOIs).

This was the moment Dante Lauretta had waited for nearly 20 years to see. A small robotic capsule was on the way back to Earth with rocks scooped from an asteroid, and Lauretta was eager to get his hands on the samples.

Led by Lauretta, scientists carefully designed the billion-dollar mission to bring home pieces of a carbon-rich asteroid thought to contain organic molecules, the building blocks necessary for life to take hold. This NASA mission, known by the acronym OSIRIS-REx, launched from Earth in 2016, collected samples from a roughly 1,600-foot-wide (500-meter) asteroid named Bennu in 2020, then set a course for return to Earth.

On September 24, the OSIRIS-REx spacecraft released the canister containing the asteroid samples to plunge into the Earth's atmosphere, while the mothership steered onto a course to take it safely back into deep space for a follow-up mission to explore a different asteroid at the end of the 2020s.

Lauretta, OSIRIS-REx's principal investigator from the University of Arizona, was a passenger in a US military helicopter circling the capsule's landing zone in the Utah desert. A heat shield protected the capsule from temperatures that built up to more than 5,000° Fahrenheit during reentry.

Then, a small drogue parachute was supposed to open to stabilize the 32-inch-wide (81-centimeter) sample return craft. About five minutes later, a larger main chute would open to slow the capsule for a gentle landing while protecting the precious asteroid material sealed inside.

At least, that was the plan. While OSIRIS-REx safely returned its asteroid sample to Earth, there were moments of high drama.

Out of order

For those watching NASA's live video coverage of the OSIRIS-REx mission's return to Earth, there were hints that something was amiss. Video imagery from a NASA tracking airplane showed the capsule tumbling toward the ground at high speed, well after the point when the drogue parachute should have been visible.

Inside a nearby helicopter, Lauretta was waiting for verbal updates on the status of the capsule.

"I heard the 100,000-foot crossing, and no drogue, and the drogue chute is supposed to come out at 100,000 feet," he recalled during a presentation last month to the National Academies' Space Studies Board. "Sixty-thousand feet, no drogue. I’m like, 'Ugh, this isn’t good.'"

The last time NASA tried to bring extraterrestrial samples back to Earth, the parachute never opened. The robotic Genesis mission ended with an uncontrolled impact in Utah, rupturing the capsule bringing back microscopic particles collected from the solar wind. Scientists were able to salvage some of the specimens, but it wasn't easy.

Lauretta called a crash like the one experienced by NASA's Genesis mission as the "worst-case scenario" for OSIRIS-REx. In that event, scientists would need to scramble to gather as much of the asteroid sample as possible from the Utah desert. Anything salvaged would need to be carefully checked for contamination from Earth's soils and life-forms.

You can watch a replay of OSIRIS-REx's landing below.

"We’re tumbling. We are in a subsonic regime, and we are not stabilized," Lauretta said. "There’s no drogue chute deployed here. Problem! So I was like trying to mentally prepare myself, because we’re on live TV, to get off this helicopter and deal with a crashed capsule in the desert."

Then, Lauretta heard confirmation from the Air Force that the OSIRIS-REx return capsule had unfurled its main parachute.

"I was like, 'What? How is that possible?'" he said. "So the main chute deployed. The drogue chute, as we’ve been able to reconstruct, went one second before the main. So it came out. It had to come out. It was in front of the main parachute in the canister, and it looks like there was a circuit issue."

NASA provided a more detailed description Tuesday of the problem that prevented the on-time deployment of the drogue chute.

The capsule was supposed to send an automated signal to deploy the drogue chute at 100,000 feet, beginning a roughly five-minute timer before a second signal would cut a retention cord for the drogue, allowing the larger parachute to unfurl and complete the landing sequence. Instead, at 100,000 feet, the signal triggered the system to cut the drogue free while it was still packed inside the capsule, according to NASA.

At 9,000 feet, the other signal sent the command to actually release the drogue chute. But with its retention cord already cut, the drogue immediately released from the capsule, and the main parachute opened as expected.

"The first signal was supposed to fire the mortar and release the drogue," Lauretta said. "The second signal was supposed to cut the cable to release the main ... It looks like the first signal cut the (cable), and then the second signal fired the mortar, so it went backwards. But it worked. We had lots of margin on that main chute. It landed safely—a beautiful pinpoint landing in the Utah desert.”

An investigation by engineers from NASA and Lockheed Martin, which built the OSIRIS-REx spacecraft and sample return vehicle, found that build plans for the mission weren't specific enough in instructing technicians who assembled the return capsule.

"In the design plans for the system, the word 'main' was used inconsistently between the device that sends the electric signals, and the device that receives the signals," NASA said in a written statement. "On the signal side, 'main' meant the main parachute. In contrast, on the receiver side 'main' was used as a reference to a pyrotechnic that fires to release the parachute canister cover and deploy the drogue.

"Engineers connected the two mains, causing the parachute deployment actions to occur out of order," NASA said.

Lauretta said scientists continue analyzing the asteroid materials delivered by OSIRIS-REx.

In a preliminary analysis of some of the dust, scientists found nearly 5 percent carbon by mass, and the material has abundant water in the form of hydrated clay minerals. It is highly plausible that asteroids like Bennu delivered the vast majority of the water now found in Earth's oceans, lakes, and rivers billions of years ago.

The team tasked with retrieving the samples from the capsule at NASA's Johnson Space Center in Houston has encountered trouble opening some of the fasteners sealing the asteroid material in the main collection chamber. While the team worked on a new plan to gather all the asteroid specimens held inside, it used tweezers to pull out some of the biggest pieces, including a roughly 1.2-inch (3-centimeter) fragment straight from Bennu.

“The organic chemistry looks fantastic," Lauretta said.

Scientific inspiration can strike at any time. For Christopher Hendon, a computational materials chemist at the University of Oregon, inspiration struck at a local coffee bar where his lab holds regular coffee hours for the Eugene campus community—a fitting venue since Hendon's research specialties include investigating the scientific principles behind really good coffee. The regulars included two volcanologists, Josef Dufek and Joshua Méndez Harper, who noted striking similarities between the science of coffee and plumes of volcanic ash, magma, and water. Thus, an unusual collaboration was born.

“It’s sort of like the start of a joke—a volcanologist and a coffee expert walk into a bar and then come out with a paper,” said Méndez Harper, a volcanologist at Portland State University. “But I think there are a lot more opportunities for this sort of collaboration, and there’s a lot more to know about how coffee breaks, how it flows as particles, and how it interacts with water. These investigations may help resolve parallel issues in geophysics—whether it’s landslides, volcanic eruptions, or how water percolates through soil.”

The result is a new paper published in the journal Matter demonstrating how adding a single squirt of water to coffee beans before grinding can significantly reduce the static electric charge on the resulting grounds. This, in turn, reduces clumping during brewing, yielding less waste and the strong, consistent flow needed to produce a tasty cup of espresso. Good baristas already employ the water trick; it's known as the Ross droplet technique, per Hendon. But this is the first time scientists have rigorously tested that well-known hack and measured the actual charge on different types of coffee.

As previously reported, there's actually an official industry standard for brewing espresso, courtesy of the Specialty Coffee Association, which sets out strict guidelines for its final volume (25-35 mL, or roughly one ounce) and preparation. The water must be heated to 92° to 95°C (197° to 203°F) and forced (at a specific pressure) through a bed of 7 to 9 grams (about a quarter of an ounce) of finely ground coffee for 20 to 30 seconds. But most coffee shops don't follow this closely, typically using more coffee, while the brewing machines allow baristas to configure water pressure, temperature, and other key variables to their liking. The result of all those variations in technique is a great deal of variability in quality and taste.

In 2020, Hendon's lab helped devise a mathematical model for brewing the perfect cup of espresso, over and over, while minimizing waste. The flavors in espresso derive from roughly 2,000 different compounds that are extracted from the coffee grounds during brewing.

So Hendon and his colleagues focused on building a mathematical model for a more easily measurable property known as the extraction yield (EY): the fraction of coffee that dissolves into the final beverage. That, in turn, depends on controlling water flow and pressure as the liquid percolates through the coffee grounds. Hendon et al. based their model on how lithium ions propagate through a battery's electrodes, which they liken to how caffeine molecules dissolve from coffee grounds.

A bunch of simulations and several thousand experimental shots of espresso later, the authors concluded that the most reproducible thing you can do is use fewer coffee beans and opt for a coarser grind with a bit less water; brew time was largely irrelevant. Conventional wisdom holds that a fine grind is best since more surface area of the resulting tamped-down coffee bed is exposed to the hot water, thus boosting the extraction yield. But the group's experiments revealed that if coffee is ground too finely, it can clog the coffee bed, thereby reducing extraction yield. It's also a big factor in the variability in taste.

This latest research focused on why the microscopic clumps form in the first place, particularly at very fine grind levels. The culprit is static electricity arising from the fracturing and friction between the beans during grinding. Hendon thought reducing that static would be a good way to eliminate those clumps. The technical term is triboelectricity, which arises from the accumulation of opposite electric charges on the surfaces of two different materials due to contact with each other. (It should not be confused with triboluminescence, the emission of cold light when a material is subjected to physical deformation—the reason Wint-O-Green Life Savers emit blue sparks when crushed, visible in the dark.)

A similar charge build-up also occurs during volcanic eruptions. “During eruption, magma breaks up into lots of little particles that then come out of the volcano in this big plume, and during that whole process, those particles are rubbing against each other and charging up to the point of producing lightning,” said Méndez Harper. “In a simplistic way, it’s similar to grinding coffee, where you’re taking these beans and reducing them to fine powder.” Since the particle-scale physics that occurs in volcanic plumes is quite difficult to study in nature, collaborating with Hendon to study triboelectric effects in coffee provided a useful smaller-scale platform.

For its experiments, the team first acquired various kinds of commercially roasted coffees, covering a broad range of colors from light to dark roasts, and lumped them into three categories: natural, washed, and decaffeinated. They used a dark roast (Starbucks Blonde Espresso Roast) with a water content of 1.3 percent to assess the surface charging of whole beans—achieved by rolling the beans down a vibrating ramp coated in various materials likely to be found in a coffeehouse environment. The beans ended up in a Faraday cup at the bottom of the ramp, where their electrical charge was calculated. The results: the beans weakly charged when rolled down steel, took on a positive charge against glass and nylon, and a negative charge against plastics like PVC and Mylar.

Next, the researchers tested the grinding process, placing a Faraday cup under the grinder chute to measure how much electrical static accumulated on the ground beans, varying coffee varieties, roasting levels, and grind settings. They determined that several different factors played a role in how much triboelectrification occurred during grinding.

For instance, lighter roasts have more internal moisture than darker roasts, and the latter is more prone to clumping. Spritzing water on the beans before grinding reduced the static electricity. “Moisture, whether it’s residual moisture inside the roasted coffee or external moisture added during grinding, is what dictates the amount of charge that is formed during grinding,” said Hendon. “Water not only reduces static electricity and therefore reduces mess as you’re grinding, but it can also make a major impact on the intensity of the beverage and, potentially, the ability to access higher concentrations of favorable flavors."

In other words, the baristas were right all along. “Some baristas may have already anecdotally arrived at our conclusions; it's validating some industry know-how,” Hendon said. “We are advocating for yet another step in producing excellent quality coffee, but it turns out you can’t cut corners if you want to achieve excellence.”

Water content also plays a role in explosive volcanic eruptions, per Dufek, charging ash particles that can lead to lightning storms as well as determining how long that ash remains airborne and how far it travels after an eruption. Among other findings: dark roasts tended to develop a negative charge, while lighter roasts took on a positive charge. Coarser grinds also resulted in less charge accumulation. Coffee bean origin or processing method did not have any impact on charging. So Hendon et al. concluded that it is the interplay between bean color and moisture content that are the primary factors at play in the phenomenon.

Matter, 2023. DOI: 10.1016/j.matt.2023.11.005  (About DOIs).

Listing image by University of Oregon

Good morning. It's December 6, and today's image features a stunning outflow from a double star about 1,000 light-years from Earth.

The James Webb Space Telescope captured this photograph and provides unprecedented detail of Herbig Haro object number 797. Such objects are luminous regions surrounding newborn stars and are formed when stellar winds or jets of gas spewing from these protostars form shockwaves colliding with nearby gas and dust at high speeds.

In this case—previously unknown to astronomers—the source of these spectacular jets is not one but two stars, which can be seen on the right-hand side of the image. Other outflows are also seen in this image, including one from the protostar in the top of the image, with its illuminated cavity walls.

These objects are in the wheelhouse of the infrared capabilities of the Webb telescope. Molecules in the outflows from the young stars are excited by the turbulent conditions and emit infrared light that Webb can collect to visualize the structure of the outflows. These molecules are heated to temperatures of thousands of degrees Celsius due to the shocks.

Space is pretty ace if you ask me.

Source: ESA/Webb, NASA & CSA, T. Ray (Dublin Institute for Advanced Studies)