It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Sunday, September 24, 2023
Brain sensitivity to insulin may be modulated by menstrual cycle
by Bob Yirka , Medical Xpress
Hypothalamic response to insulin spray in both phases of the menstrual cycle. a, Hypothalamus region of interest in coronal (top), sagittal (middle) and axial section planes (bottom). b, Absolute changes in CBF in the hypothalamus from before treatment to 30 min after intranasal insulin administration in the follicular (left) and luteal (right) phases of the menstrual cycle. In the follicular phase, insulin induced a significant reduction in hypothalamic CBF, whereas this effectwas absent in the luteal phase. Bar graphs are shown with means and individual data points, and error bars represent s.e.m. Data were analyzed by two-sided paired t-tests; *P = 0.02; N = 15 participants in both cycle phases. Credit: Nature Metabolism (2023). DOI: 10.1038/s42255-023-00869-w
A combined team of diabetes specialists from Eberhard Karls University Tübingen and Heinrich Heine University Düsseldorf, both in Germany, has found evidence that suggests brain sensitivity to insulin may be modulated by the menstrual cycle in women.
In their study, reported in the journal Nature Metabolism, the group conducted a clinical trial involving monitoring the insulin levels of female volunteers. Nils Kroemer, with the University of Bonn, has published a News & Views piece in the same journal issue outlining the work done by the group on this new effort.
Prior research has suggested that the presence of insulin in the brain can lead to changes in eating behavior, whole-body metabolism and fat storage. How this works is not well understood. Making things even murkier, as the researchers note, is that virtually all prior research in this area has involved testing the impact of insulin on the brains of men.
In this new effort, the research team sought to learn more about the impact of insulin on women's brains. To that end, they conducted a clinical trial that involved testing the impact of insulin on the brains of 11 female volunteers during two time periods; during their first day of ovulation, and just after they had ovulated.
To measure the impact of insulin on their brains, the volunteers underwent hyperinsulinemic-euglycemic clamps—a procedure that can be used to measure insulin sensitivity. Some of the women were also given intranasal insulin doses during the procedure while others received a placebo. The researchers found that during the first day of ovulation, the brain was more sensitive to the insulin, but not during the days just after ovulation.
Next, the research team administered MRI scans to 15 different female volunteers to learn more about the impact of insulin on the hypothalamus during menstrual cycles. They found the same results—the women exhibited higher hypothalamus sensitivity to insulin just prior to the onset of ovulation but not afterward.
The researchers suggest their findings explain why so many women experience hunger just prior to getting their period, why their metabolism slows and why weight gain is so much more likely. Kroemer suggests that the female body reacts this way as a means of storing up energy to sustain a pregnancy, should it occur.
More information: Julia Hummel et al, Brain insulin action on peripheral insulin sensitivity in women depends on menstrual cycle phase, Nature Metabolism (2023). DOI: 10.1038/s42255-023-00869-w
Generation of Ago2 knockout Ae. aegypti lines and the effect of Ago2 disruption on arbovirus infection and transmission. a flowchart of experiment design. b gene structure of Ago2, predicted functional domains, and guide RNA (gRNA) design for CRISPR/Cas9. The table shows data from generating Ago2 knockout lines. cAgo2 amplification in Ago2knockout lines. P, parental line Cas9; HE, heterozygous mutants; HO, homozygous mutants. d virus titer in Ago2 knockout (Ago2−/− and ArgoN−/−) and Cas9 mosquitoes on various days post-infection (dpi) with DENV2, ZIKV, or MAYV. IFA detection of MAYV (e) and DENV2 (f) antigen in midguts of Cas9 and Ago2−/− mosquitoes at different days post virus infection. MAYV and DENV2 were detected with the corresponding monoclonal antibody (green). Nuclei were stained with DAPI (blue). g virus titer and infection prevalence in the feeding solution collected from a feeder exposed to a group of females at 14 dpi with DENV2 or 5 dpi with MAYV. The Liverpool strain was used as a control (WT). For DENV2 infection,n = 16 for WT andn = 15 forAgo2−/−; for MAYV infection,n = 19 for both WT andAgo2−/−.hpercentage of the fed mosquitoes in each group of females at 14 dpi with DENV2 or 5 dpi with MAYV. Data were presented as box and whiskers (Min to Max).ivirus titer plotted against the number of the fed mosquitoes in each cup.jvirus titer and infection prevalence of individual saliva samples collected fromAgo2−/−and WT at 14 dpi with DENV2 or 5 dpi with MAYV. For DENV2 infection,n = 62 for WT andn = 61 forAgo2−/−; for MAYV infection,n = 56 for both WT andAgo2−/−. Each experiment comprisedat least two biological replicates, and the data were pooled for generating the graphs. Virus titers were determined by plaque assay, and horizontal lines indicate the medians of the virus titer (d,gandj).Pvalues were determined by an unpaired two-sided Mann-Whitney test for virus titer, an unpaired two-sided Fisher’s exact test for infection prevalence, or an unpaired two-sidedt-test for (h). Source data are provided as a Source Data file. Credit:Nature Communications(2023). DOI: 10.1038/s41467-023-41370-y
Researchers from the Johns Hopkins Malaria Research Institute at the Johns Hopkins Bloomberg School of Public Health have made an important finding about Aedes aegypti mosquitoes—one that could one day lead to better methods for reducing the mosquito-to-human transmission of dengue, yellow fever, Zika, and other harmful and sometimes deadly viruses
Ae. aegypti mosquitoes do not succumb to these viruses when infected and continue to move and feed normally. As such, the infected mosquitoes can pass their viral cargoes on to humans. The researchers discovered that an Ae. aegypti protein, Argonaute 2, has a key role—via several biological mechanisms—in keeping mosquitoes healthy and active despite these infections.
The discovery represents a significant advance in understanding mosquito biology. It also hints at a strategy that would aim to shut down Ae. aegypti mosquitoes' defenses whenever they become infected by certain viruses—killing the mosquitoes and thereby reducing the transmission of those viruses by Ae. aegypti to humans.
Instead of making mosquitoes more resistant to the viruses, the discovery opens a possible path for making mosquitoes more susceptible and less tolerant to virus infection, which would impair their ability to transmit disease.
The research was published online September 18 in Nature Communications.
"Researchers have long wondered why Ae. aegypti mosquitoes don't get sick when they are infected by these viruses—our findings effectively solve this mystery and suggest a potential new mosquito-based disease control strategy that merits further study," says study senior author George Dimopoulos, Ph.D., a professor in the Johns Hopkins Malaria Research Institute and in the Bloomberg School's Department of Molecular Microbiology and Immunology.
The study's lead author was Shengzhang Dong, Ph.D., a senior research associate in the Bloomberg School's Department of Molecular Microbiology and Immunology.
Ae. aegypti mosquitoes transmit "arthropod-borne" or "arbo-" viruses including dengue virus, yellow fever virus, Zika virus, chikungunya virus, and Mayaro virus. Each year these pathogens sicken millions of people around the world each year, killing tens of thousands. There are no antiviral therapies for any of these viruses.
Currently, a vaccine is available for yellow fever virus. One dengue vaccine is approved by the Food and Drug Administration for individuals between six and 16 who have had prior dengue infection. Disease control methods for Ae. aegyptiemphasize the use of insecticides, which have had limited success and have led to insecticide resistance.
Ae. aegypti mosquitoes are effective vectors of arborviruses because they can sustain significant infections with these viruses without suffering costs to their overall ability to reproduce—what biologists call "fitness." If the mosquitoes' fitness was impaired, they would likely have evolved strong defenses against these pathogens. Instead, they somehow ended up with a live-and-let-live balance that allows them to carry at least moderate viral loads without apparent adverse effects.
In the new study, Dimopoulos and Dong examined the role of Argonaute 2 (Ago2), a protein that in mosquitoes serves as part of an important antiviral mechanism known as the small interfering RNA (siRNA) pathway, which works by recognizing and destroying viral RNAs.
The researchers found that in Ae. aegypti mosquitoes lacking the Ago2 gene, the siRNA pathway is impaired, arborvirus infection becomes more severe, and the mosquitoes' ability to transmit these viruses drops sharply—as they sicken, feed less, and often die within days.
The scientists showed that this increased mortality is caused not only by the impairment of the siRNA antiviral pathway, but also by defects in two other processes that happen to depend on Ago2: DNA repair, and a basic waste-removal process called autophagy. Ago2-deficient mosquitoes exposed to arborviruses were left with hyperinfections, extensive DNA damage, and the accumulation of molecular waste in their dying cells.
Apart from illuminating an important aspect of Ae. aegypti biology, the findings point to a possible new arboviral disease control strategy. This would be to engineer the mosquitoes so that arbovirus infections trigger the loss of their tolerance mechanisms, perhaps via the inhibition of Ago2. Arborvirus-carrying Ae. aegypti mosquitoes would thus die quickly, whereas the much greater number of non-arborvirus carrying Ae. aegypti should be unaffected.
"The biology of mosquito susceptibility and tolerance to infection is an interesting area of exploration for other pathogens as well," says Dimopoulos. "For instance, mosquitoes that transmit malaria parasites could perhaps also be engineered to become sick and succumb to infection."
Dimopoulos and his research group are now exploring possible ways of engineering Ae. aegypti to test this possible new disease-control strategy.
More information: Shengzhang Dong et al, Aedes aegypti Argonaute 2 controls arbovirus infection and host mortality, Nature Communications (2023). DOI: 10.1038/s41467-023-41370-y
A non-invasive way to turn a cockroach into a cyborg
by Bob Yirka , Tech Xplore
Non-invasive electrodes with resilient and conductive membrane for cyborg insects. Credit: npj Flexible Electronics (2023). DOI: 10.1038/s41528-023-00274-z
A team of mechanical engineers at Nanyang Technological University in Singapore has found a way to electronically control cockroaches without injuring them. In their paper published in the journal npj Flexible Electronics, the group describes the new technology they used to remotely control the cockroaches and the benefits of doing so.
Prior research teams have created a variety of cyborg cockroaches, but they all had one feature in common—they all involved attaching probes to the insect's nervous system—procedures that led to damage to the insect, and likely some degree of pain.
In this new effort, the researchers noted that damaging cockroaches during attempts to control them results in a very short life expectancy, which then results in very little payoff for a lot of work. They also suggest such research is unethical because of the pain inflicted on the cockroaches. In this new effort, they have found a way to control cockroaches that does not involve cutting into them, resulting in a much longer lifespan
Noting that prior research had suggested that cockroaches could be coaxed into turning by stimulating one or the other of their antennae, the research team found a way to attach cuffs to each of them that do not cause damage. They created a sleeve that fits individually over each antenna. The sleeve is made of gold and plastic printed in layers. Fixed in place by a blast of ultraviolet light, the sleeves shrink like plastic shrink-wrap.
Both sleeves were connected by a short wire to a tiny backpack that was glued to the back of the cockroach. Signals were sent wirelessly to the backpack from a hand controller, which sent very gentle electric jolts to one antenna or the other, resulting in the cockroach turning in a desired direction. The research team also glued an electrode to the cockroach's belly, that when stimulated in just the right way, made the cockroach run faster or slower.
The researchers tested their cockroach cyborg by having it run around a tiny S-shaped track and also by having it navigate an obstacle course created by placing stones on a flat base in random places. In so doing, they found they could get their cyborg to go where they wanted, when they wanted.
More information: Qifeng Lin et al, Resilient conductive membrane synthesized by in-situ polymerisation for wearable non-invasive electronics on moving appendages of cyborg insect, npj Flexible Electronics (2023). DOI: 10.1038/s41528-023-00274-z
New research has revealed a potentially important role ginger supplements can play in controlling inflammation for people living with autoimmune diseases.
The research published in JCI Insight focused on studying the impact of ginger supplementation on a type of white blood cell called the neutrophil. The study was especially interested in neutrophil extracellular trap (NET) formation, also known as NETosis, and what it may mean for controlling inflammation.
The study found ginger consumption by healthy individuals makes their neutrophils more resistant to NETosis. This is important because NETs are microscopic spider web-like structures that propel inflammation and clotting, which contribute to many autoimmune diseases, including lupus, antiphospholipid syndrome and rheumatoid arthritis.
"There are a lot of diseases where neutrophils are abnormally overactive. We found that ginger can help to restrain NETosis, and this is important because it is a natural supplement that may be helpful to treat inflammation and symptoms for people with several different autoimmune diseases," said senior co-author Kristen Demoruelle, MD, Ph.D., associate professor of medicine at the University of Colorado School of Medicine on the University of Colorado Anschutz Medical Campus.
In a clinical trial, the researchers found that daily intake of a ginger supplement for seven days (20 mg of gingerols/day) by healthy volunteers boosted a chemical inside the neutrophil called cAMP. These high levels of cAMP then inhibited NETosis in response to various disease-relevant stimuli.
"Our research, for the first time, provides evidence for the biological mechanism that underlies ginger's apparent anti-inflammatory properties in people," said senior co-author Jason Knight, MD, Ph.D., associate professor in the Division of Rheumatology at the University of Michigan.
The researchers say that many people with inflammatory conditions are likely to ask their health care providers whether natural supplements could be helpful for them or they already take supplements, like ginger, to help manage symptoms. Unfortunately, the precise impact on disease is often unknown.
The researchers hope that providing more evidence about ginger's benefits, including the direct mechanism by which ginger impacts neutrophils, will encourage health care providers and patients to more strategically discuss whether taking ginger supplements as part of their treatment plan could be beneficial.
"There are not a lot of natural supplements, or prescription medications for that matter, that are known to fight overactive neutrophils. We, therefore, think ginger may have a real ability to complement treatment programs that are already underway. The goal is to be more strategic and personalized in terms of helping to relieve people's symptoms," Knight adds.
As a next step, the researchers hope to undertake clinical trials of ginger in patients with autoimmune and inflammatory diseases where neutrophils are overactive, such as lupus, rheumatoid arthritis, antiphospholipid syndrome and even COVID-19.
More information: Ginger intake suppresses neutrophil extracellular trap formation in autoimmune mice and healthy humans, JCI Insight (2023).
Sex life discovery raises IVF hope for endangered purple cauliflower soft coral
by Meryl Larkin, David Harasti, Kirsten Benkendorff, Stephen D. A. Smith and Tom R Davis, The Conversation
The life cycle of the purple cauliflower coral Dendronephthya australis begins with an egg being fertilised by sperm, proceeds to embryo cell division within 2-4 hours, to fully grown larvae by day 5, to metamorphosis to polyp from 8 days of age. Credit: Meryl Larkin
Vital coastal habitat was destroyed in the devastating floods that hit New South Wales in 2021 and 2022.
The purple cauliflower soft coral Dendronephthya australis, now listed as an endangered species, was almost completely wiped out in the Port Stephens estuary and along the coast. That's a tragedy because this coral shelters young snapper and the endangered White's seahorse.
Unfortunately, a lack of knowledge hampered recovery efforts—until now.
In our new research we discovered how the coral reproduces. We used IVF (in-vitro fertilization) to create baby coral in the lab. And we successfully transplanted the coral into the wild. This offers new hope for the survival of the species.
Variety is the spice of life
Corals have a complicated sex life. There's more than one way to "do it". And gender varies too.
Corals can reproduce asexually, meaning they create genetic copies of themselves. This process often entails shedding polyps that can attach to reefs to form new colonies.
Using this process is a common approach for coral restoration. It's a bit like propagating plants. Cuttings or fragments are removed from adult colonies, briefly maintained in the lab, and then new corals are transplanted into the wild. This isn't a simple process for soft corals, though we have been exploring ways to make this work for Dendronephthya australis. Understanding the sex life of purple cauliflower soft coral offers hope for the species.
Many corals are hermaphrodites, which means they have both male and female reproductive organs. Others form colonies that are entirely male or female. And some mix or swap sexes.
Spawning is the release of eggs and sperm. Again, corals can use various techniques. Broadcast spawning is where eggs and sperm are released into the water column. Brooding is where eggs are fertilized within colonies and later released as larvae.
But until sexual reproduction of an individual species is observed, their sex life remains a private matter.
A chance discovery in the lab
We were growing coral in the lab, raising asexual clones from fragments, when we noticed something unusual.
There were small orange dots inside some of the corals. These were much larger than the grains of dry orange "coral food" we fed them. So they had to be something else.
Unfertilised eggs (orange dots) were observed in Dendronephthya australis fragments for the first time. Credit: Meryl Larkin
We soon realized the orange dots were unfertilised eggs. Half of the fragments in our care contained eggs. As sperm is much smaller, we had to sacrifice small portions of the remaining coral fragments for closer inspection of their contents (under a microscope). In doing this, we discovered the other half were sperm-bearing.
As fate would have it, we had collected fragments from two donor colonies—one female and one male. By chance, we discovered Dendronephthya australis is "gonochoric" (meaning colonies are either male or female).
We watched the corals carefully over the following weeks and made more discoveries. Females spawned (released their eggs) around the "neap tide" (when the moon appears half full) during the summer months.
Maybe the coral evolved to spawn when tidal currents are slowest, to maximize the chance of fertilization.
Coral IVF for making babies
We used IVF techniques to fertilize harvested eggs. Cell division occurred within hours. Mobile larvae grew over the following week.
Researchers achieved larval settlement, witnessing the change to the single polyp stage of the soft coral. Credit: David Harasti
From eight days of age, the larvae started to transform into polyps; we were the first people to witness these tiny cauliflower coral babies (as single polyps).
Within just a few weeks, we had produced 280 babies from just a few coral fragments.
Understanding how the purple cauliflower coral reproduces is important for several reasons:maintaining genetic diversity: if the sex ratio becomes unbalanced, the effective population size will be lower than the total number of remaining individuals achieving fertilization: broadcast spawning in corals is density-dependent. That means if more colonies are lost, the chance of natural sexual reproduction decreases restoring gender balance: any attempt to grow more coral from fragments will need to ensure both male and female colonies are represented scaling up production: sexual reproduction provides an opportunity to raise more baby corals while maintaining genetic diversity in the population.
Ongoing restoration work
Since this discovery, we have successfully repeated these IVF techniques. We transplanted hundreds of coral babies and released thousands of larvae back into Port Stephens.
Four-month-old juvenile coral transplanted in Port Stephens. Credit: Meryl Larkin
Early results suggest some IVF babies survived at least the first 18 months and performed better than the asexual fragments.
We plan to implement the IVF program annually. We're optimistic that we can boost the population of this endangered coral in ways never thought possible.
Historians race to find Great Lakes shipwrecks before quagga mussels destroy the sites
by Todd Richmond
This Aug. 17, 2021 photo shows Quagga mussels cover the engine of a Bell P-39 Airacobra military plane in Lake Huron, Mich., as maritime archaeologist Carrie Sowden, rear, documents the site. Archaeologists are scrambling to locate Great Lakes shipwrecks and downed planes before quagga mussels destroy them. Credit: Wayne Lusardi via AP
The Great Lakes' frigid fresh water used to keep shipwrecks so well preserved that divers could see dishes in the cupboards. Downed planes that spent decades underwater were left so pristine they could practically fly again when archaeologists finally discovered them.
Now, an invasive mussel is destroying shipwrecks deep in the depths of the lakes, forcing archaeologists and amateur historians into a race against time to find as many sites as they can before the region touching eight U.S. states and the Canadian province of Ontario loses any physical trace of its centuries-long maritime history.
"What you need to understand is every shipwreck is covered with quagga mussels in the lower Great Lakes," Wisconsin state maritime archaeologist Tamara Thomsen said. "Everything. If you drain the lakes, you'll get a bowl of quagga mussels."
Quagga mussels, finger-sized mollusks with voracious appetites, have become the dominant invasive species in the lower Great Lakes over the past 30 years, according to biologists.
The creatures have covered virtually every shipwreck and downed plane in all of the lakes except Lake Superior, archaeologists say. The mussels burrow into wooden vessels, building upon themselves in layers so thick they will eventually crush walls and decks. They also produce acid that can corrode steel and iron ships. No one has found a viable way to stop them.
Wayne Lusardi, Michigan's state maritime archaeologist, is pushing to raise more pieces of a World War II plane flown by a Tuskegee airman that crashed in Lake Huron in 1944.
"Divers started discovering (planes) in the 1960s and 1970s," he said. "Some were so preserved they could fly again. (Now) when they're removed the planes look like Swiss cheese. (Quaggas are) literally burning holes in them."
Quagga mussels, native to Russia and Ukraine, were discovered in the Great Lakes in 1989, around the same time as their infamous cousin species, zebra mussels. Scientists believe the creatures arrived via ballast dumps from transoceanic freighters making their way to Great Lakes ports.
Unlike zebra mussels, quaggas are hungrier, hardier and more tolerant of colder temperatures. They devour plankton and other suspended nutrients, eliminating the base level of food chains. They consume so many nutrients at such high rates they can render portions of the murky Great Lakes as clear as tropical seas. And while zebra mussels prefer hard surfaces, quaggas can attach to soft surfaces at greater depths, enabling them to colonize even the lakes' sandy bottoms.
After 30 years of colonization, quaggas have displaced zebra mussels as the dominant mussel in the Great Lakes. Zebras made up more than 98% of mussels in Lake Michigan in 2000, according to the University of California, Riverside's Center for Invasive Species Research. Five years later, quaggas represented 97.7%.
For wooden and metal ships, the quaggas' success has translated into overwhelming destruction.
The mussels can burrow into sunken wooden ships, stacking upon themselves until details such as name plates and carvings are completely obscured. Divers who try to brush them off inevitably peel away some wood. Quaggas also can create clouds of carbon dioxide, as well as feces that corrode iron and steel, accelerating metal shipwrecks' decay.
Quaggas have yet to establish a foothold in Lake Superior. Biologists believe the water there contains less calcium, which quaggas need to make their shells, said Dr. Harvey Bootsma, a professor at the University of Wisconsin-Milwaukee's School of Freshwater Sciences.
This Aug. 15, 2021 photo, videographer Nicholas Lusardi investigates the wing of a downed P-39 Airacobra in Lake Huron, Mich. The plane that crashed during a training mission in April 1944, killing Lt. Frank Moody, a Tuskegee airman. Archaeologists are racing to document Great Lakes shipwrecks and downed planes before quagga mussels disintegrate them. Credit: Wayne Lusardi via AP
That means the remains of the Edmund Fitzgerald, a freighter that went down in that lake during a storm in 1975 and was immortalized in the Gordon Lightfoot song, "The Ballad of the Edmund Fitzgerald," are safe, at least for now.
Lusardi, Michigan's state maritime archaeologist, ticked off a long list of shipwreck sites in the lower Great Lakes consumed by quaggas.
His list included the Daniel J. Morrel, a freighter that sank during a storm on Lake Huron in 1966, killing all but one of the 29 crew members, and the Cedarville, a freighter that sank in the Straits of Mackinac in 1965, killing eight crew members. He also listed the Carl D. Bradley, another freighter that went down during a storm in northern Lake Michigan in 1958, killing 33 sailors.
The plane Lusardi is trying to recover is a Bell P-39 that went down in Lake Huron during a training exercise in 1944, killing Frank H. Moody, a Tuskegee airman. The Tuskegee Airmen were a group of Black military pilots who received training at Tuskegee Army Air Field in Alabama during World War II.
Brendon Baillod, a Great Lakes historian based in Madison, has spent the last five years searching for the Trinidad, a grain schooner that went down in Lake Michigan in 1881. He and fellow historian Bob Jaeck finally found the wreck in July off Algoma, Wisconsin.
The first photos of the site, taken by a robot vehicle, showed the ship was in unusually good shape, with intact rigging and dishes still in cabins. But the site was "fully carpeted" with quagga mussels, Baillod said.
"It has been completely colonized," he said. "Twenty years ago, even 15 years ago, that site would have been clean. Now you can't even recognize the bell. You can't see the nameboard. If you brush those mussels off, it tears the wood off with it."
Quagga management options could include treating them with toxic chemicals; covering them with tarps that restrict water flow and starve them of oxygen and food; introducing predator species; or suffocating them by adding carbon dioxide to the water.
So far nothing looks promising on a large scale, UW-Milwaukee's Bootsma said.
"The only way they will disappear from a lake as large as Lake Michigan is through some disease, or possibly an introduced predator," he said.
That leaves archaeologists and historians like Baillod scrambling to locate as many wrecks as possible to map and document before they disintegrate under the quaggas' assaults.
At stake are the physical remnants of a maritime industry that helped settle the Great Lakes region and establish port cities such as Milwaukee, Detroit, Chicago and Toledo, Ohio.
"When we lose those tangible, preserved time capsules of our history, we lose our tangible connection to the past," Baillod said. "Once they're gone, it's all just a memory. It's all just stuff in books."
Artist’s concept of the Parker Solar Probe spacecraft approaching the sun. Launching in 2018, Parker Solar Probe will provide new data on solar activity and make critical contributions to our ability to forecast major space-weather events that impact life on Earth. Credit: NASA
NASA's Parker Solar Probe has racked up an impressive list of superlatives in its first five years of operations: It's the closest spacecraft to the sun, the fastest human-made object and the first mission to ever "touch the sun."
Now, Parker has one more feather to add to its sun-kissed cap: It's the first spacecraft ever to fly through a powerful solar explosion near the sun.
As detailed in a new study published Sept. 5 in The Astrophysical Journal—exactly one year after the event occurred—Parker Solar Probe passed through a coronal mass ejection (CME).
These fierce eruptions can expel magnetic fields and sometimes billions of tons of plasma at speeds ranging from 60 to 1,900 miles (100 to 3,000 kilometers) per second. When directed toward Earth, these ejections can bend and mold our planet's magnetic field, generating spectacular auroral shows and, if strong enough, potentially devastate satellite electronics and electrical grids on the ground.
Cruising on the far side of the sun just 5.7 million miles (9.2 million kilometers) from the solar surface—22.9 million miles (36.8 million kilometers) closer than Mercury ever gets to the sun—Parker Solar Probe first detected the CME remotely before skirting along its flank. The spacecraft later passed into the structure, crossing the wake of its leading edge (or shock wave), and then finally exited through the other side.
A composite of images collected by Parker Solar Probe’s Wide-field Imager for Solar Probe (WISPR) instrument captures the moment the spacecraft passed through a coronal mass ejection (CME) on Sept. 5, 2022. The event becomes visible at 0:14 seconds. The sun, depicted on the left, comes closest on Sept. 6, when Parker reached its 13th perihelion. The sound in the background is magnetic field data converted into audio. Credit: NASA/Johns Hopkins APL/Naval Research Laboratory/Brendan Gallagher/Guillermo Stenborg/Emmanuel Masongsong/Lizet Casillas/Robert Alexander/David Malaspina
In all, the sun-grazing spacecraft spent nearly two days observing the CME, providing physicists an unparalleled view into these stellar events and an opportunity to study them early in their evolution.
"This is the closest to the sun we've ever observed a CME," said Nour Raouafi, the Parker Solar Probe project scientist at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, which built the spacecraft within NASA's timeline and budget, and currently manages and operates the mission. "We've never seen an event of this magnitude at this distance."
The CME on Sept. 5, 2022, was an extreme one. As Parker passed behind the shock wave, its Solar Wind Electrons, Alphas and Protons (SWEAP) instrument suite clocked particles accelerating up to 840 miles (1,350 kilometers) per second. Had it been directed toward Earth, Raouafi suspects it would have been close in magnitude to the Carrington Event—a solar storm in 1859 that is held as the most powerful on record to hit Earth.
"The potential damage of this class of event, large and very fast CMEs, can be colossal," Raouafi said.
Physicists have surmised that such an event today, if detected too late, could disable communications systems and spawn continent-wide blackouts.
Despite the eruption's power, Parker seemed unfazed. Its heat shield, radiators and thermal protection system ensured the Probe's temperatures never changed, said Jim Kinnison, the Parker Solar mission systems engineer at APL. Its autonomy system even triggered mitigation plans so the avionics suite worked without interruption. In fact, the only effect the CME had on the spacecraft was a slight torque—a tiny turn for which it quickly compensated.
"We knew from the beginning that Parker Solar Probe would fly through CMEs. That was part of the science objectives when the mission was established, so we designed the spacecraft from the start with an eye to surviving and, better yet, performing the science mission while in a CME," Kinnison said. "All in all, Parker proved itself to be robust and pretty tough, and all the hard work done in the design phase paid off."
Physicists have been interested in deciphering the forces that drive these stellar explosions and accelerate particles to such incredible clips. The only way to do that was to fly through one at the sun.
The science team determined the timeline of events and Parker's location during the CME by comparing measurements collected within the CME with those gathered outside it, including imagery taken by the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) instrument on NASA's STEREO spacecraft. They built a simple model of the event, but given that nobody has ever taken measurements this early in a CME's development, some pieces were difficult to reconcile.
"You try simplified models to explain certain aspects of the event, but when you are this close to the sun, none of these models can explain everything," said Orlando Romeo, a space physicist at the University of California, Berkeley, and the lead author of the new study.
The team had determined three major intervals during the event, but piecing them together, Romeo said, was particularly confusing. Two sections they had seen before in CMEs when they arrived at Earth: the shock wave near the event's front followed by CME plasma, and another portion with magnetic and plasma characteristics typical of the sun's solar wind. But the third section—a low-density-region with slow-moving particles during the event—was new and odd.
"We're still not exactly sure what is happening there or how to connect it to the other two sections," Romeo said.
Advanced models that include more of the spacecraft's measurements will likely help, but passing through another CME would do even better. With the sun near the peak of its activity cycle, CMEs should happen more frequently. With a bit of luck, the team hopes, Parker Solar Probe will fly through several more ejections as it winds ever closer to the sun.
More information: O. M. Romeo et al, Near-Sun In Situ and Remote-sensing Observations of a Coronal Mass Ejection and its Effect on the Heliospheric Current Sheet, The Astrophysical Journal (2023). DOI: 10.3847/1538-4357/ace62e
