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Protons May Have Outsize Influence on Properties of Neutron Stars

A study conducted by an international consortium called the CLAS Collaboration, made up of 182 members from 42 institutions in 9 countries, has confirmed that increasing the number of neutrons as compared to protons in the atom’s nucleus also increases the average momentum of its protons. The result, reported in the journal Nature, has implications for the dynamics of neutron stars.

Neutron stars are the smallest, densest stars in the Universe. True to their name, neutron stars are composed almost entirely of neutrons. Duer et al suggest that some properties of neutron stars may be influenced not only by their multitude of densely packed neutrons, but also by a substantially smaller fraction of protons — positively charged particles that make up just 5% of a neutron star. This is an illustration of a neutron star. Image credit: Casey Reed, Penn State University.

The nucleus of an atom is packed with protons and neutrons, though not quite as densely as in neutron stars.

Occasionally, if they are close enough in distance, a proton and a neutron will pair up and streak through an atom’s nucleus with unusually high energy.

Such ‘short-range correlations,’ as they are known, can contribute significantly to the energy balance and overall properties of a given atomic nucleus.

The researchers from the CLAS Collaboration based their study on data collected by the ‘Continuous Electron Beam Accelerator Facility’ Large Acceptance Spectrometer (CLAS), a particle accelerator and detector based at Jefferson Laboratory in Virginia.

CLAS was designed to detect and record the multiple particles that are emitted when beams of electrons impinge on atomic targets.

The team re-analyzed data from an experiment conducted in 2004, in which CLAS produced a 5.01 GeV beam of electrons to probe nuclei of carbon, aluminum, iron and lead. Along with their varying sizes, each of the four types of atoms has different ratios of neutrons to protons in their nuclei, with carbon having the fewest neutrons and lead having the most.

“When the electron comes in and hits the nucleus, we have struck a proton or a neutron. We detected the scattered electron and the scattered proton or neutron,” said Meytal Duer, a graduate student at Tel Aviv University.

“This is the first study to measure both protons and neutrons in short-range correlations and compare the high-momentum fraction carried by each.”

Duer and colleagues found that, as the relative number of neutrons in an atom increased, so did the probability that a proton would form an energetic pair.

The likelihood that a neutron would pair up, however, stayed about the same.

This trend suggests that, in objects with high densities of neutrons, the minority protons carry a disproportionally large part of the average energy.

“When we’ve got 50% more neutrons in the nucleus, we’ve also got 50% more high-momentum protons than we had before,” said MIT researcher Dr. Or Hen, co-author of the study and spokesperson for the data mining collaboration.

“This may be a consequence of the pair preference phenomenon exhibited by short-range correlations. That is, protons and neutrons both prefer to pair with particles different from themselves by 20 to 1. In neutron-rich nuclei, the few protons will have more pairing opportunities than the plentiful neutrons.”

“A main result of the study is that as the nucleus becomes more and more neutron rich, the pairing probability of neutrons saturates, while the pairing probability of protons grows.”

“The trend of energetic protons in neutron-rich atoms may extend to even more neutron-dense objects, such as neutron stars. The role of protons in these extreme objects may then be more significant than people previously suspected,” Dr. Hen added.

“This revelation may shake up scientists’ understanding of how neutron stars behave.”

“For instance, as protons may carry substantially more energy than previously thought, they may contribute to properties of a neutron star such as its stiffness, its ratio of mass to size, and its process of cooling.”

“All these properties then affect how two neutron stars merge together, which we think is one of the main processes in the Universe that create nuclei heavier than iron, such as gold,” he said.”

“Now that we know the small fraction of protons in the star is very highly correlated, we will have to rethink how neutron stars behave.”


New Report Presents Current Picture of How Pharma is Communicating and Disseminating Medical Information to External Stakeholders

CHAPEL HILL, N.C.Aug. 17, 2018 /PRNewswire/ — Disseminating medical information to external stakeholders such as physicians and payers is an important activity that has to be done right the first time.

And just as pharmaceutical companies differ in which external groups they focus on for sharing medical information about products and pipelines, so too do they differ in whether the information is shared proactively or reactively. To get a current picture of the practices of Medical Information (MI) groups, Best Practices, LLC has published a new study that examines with whom and how pharmaceutical companies are sharing medical information with external stakeholders.

Best Practices in Communicating and Disseminating Medical Information to External Stakeholders” is a 56-page study that:

  • Examines how MI groups communicate with various external stakeholder groups
  • Explores the mediums used when disseminating medical information to external stakeholders
  • Establishes protections used by Medical Information groups when communicating with external stakeholders
  • Highlights the proactive/ reactive nature of communication with external stakeholder groups

The study found that only a minority of participants share information with payers and formulary decision-makers; the growing importance of these groups suggests that the number of companies providing data to these two external groups will grow sooner rather than later.

This benchmarking study provides medical information leaders with peer benchmarks that will strengthen recommendations to leadership teams on how to share sensitive medical information.

For this research, Best Practices, LLC engaged 31 Medical Information leaders at 26 companies through a benchmarking survey. Data in this research are presented in two segments: Large Companies and Small/Mid-Sized Companies.

To learn more about this report, download a complimentary report excerpt at

For related research, visit the Best Practices, LLC Web site at


Best Practices, LLC is a leading benchmarking, consulting and advisory services firm serving biopharmaceutical and medical device companies worldwide. Best Practices, LLC’s clients include all the top 10 and 48 of the top 50 global healthcare companies. The firm conducts primary research and consulting using its comprehensive proprietary benchmarking tools and analysis.

Naked mole-rats defy conventions of aging and reproduction

Naked mole-rats live in colonies of two breeders and around 300 non-breeding workers. Although the breeding pair carries the metabolic cost of reproduction and, in the queen’s case, lactation, they live longer than non-breeders and remain fertile throughout their lives. Researchers at the Leibniz Institute on Aging in Germany investigated the genetic mechanisms beneath this apparent paradox. Their findings are published in the open access journal BMC Biology.

Dr Martin Bens, the corresponding author said: “Our results indicate that when naked mole-rats mature into breeders, it changes their aging rates, meaning that breeders are able to live longer than non-breeders. This is surprising, as evidence from other species suggest that reproduction, which ensures the survival of the species as a whole, reduces the lifespan of the individual. In naked mole-rats reproduction appears to prolong the breeders’ lifespan. This goes against the common expectation that mammals either invest resources in a long life or in reproduction.”

The researchers analyzed the transcriptomes – the sum of all transcribed genes – for tissue samples taken from a range of organs, including heart, liver, and gonads. They compared the transcriptomes of naked mole-rat breeders to that of non-breeders, as well as to breeding and non-breeding guinea pigs, which are close relatives of the naked mole-rat but have a shorter lifespan.

The authors found that genes related to aging were expressed differently in samples from breeding naked mole-rats than those from guinea pigs and non-breeding naked mole-rats. For example, a gene related to muscle regeneration showed higher expression in naked mole-rat breeders which may be linked to higher resistance to muscle loss during aging. Gene expression changes like this may contribute to the exceptionally long lifespan of naked mole-rat breeders.

Dr Bens said: “Unlike non-breeding guinea pigs and other rodents, non-breeding naked mole-rats are not sexually dimorphic; they show no differences in body size, body mass or external genitalia, as well as few behavioral differences. One of the main and surprising findings of our study is that transcribed genes in non-breeding naked mole-rats also show no significant differences between females and males. However, we found that the transcriptome changes significantly when they mature into breeders.”

When the authors separated non-breeding naked mole-rats from colonies and paired them with naked mole-rats of the opposite sex, the workers transitioned into breeders. The transition was accompanied by physical and behavioral changes that differed between males and females – the animals became sexually dimorphic. Sexual maturation was also associated with a change in gene expression levels linked to extended life and health span.

Dr Bens said: “Deeper investigations of naked mole-rat transcriptome data can help us understand how sexual maturation is regulated. This could potentially help us better understand sexual maturation in humans, where the onset of puberty varies between individuals and is influenced by a variety of factors such as stress and nutrition. Variations in puberty onset have implications for the risk for diseases such as breast cancer or cardiovascular diseases. Our data may help identify targets to mitigate these variations.”

In another study titled ‘Species comparison of liver proteomes reveals links to naked mole-rat longevity and human aging,’ published in BMC Biology on the same day, Dr Bens and colleagues compared the liver of naked mole-rats with those of guinea pigs to further investigate the molecular mechanisms that underlie naked mole-rat longevity.

Alessandro Ori, the corresponding author of the study said: “We found that naked mole-rat livers have a unique expression pattern of mitochondrial proteins that result in distinct metabolic features of their mitochondria, including an increased capacity to utilize fatty acids. We were also able to show that similar molecular networks are affected during aging in both naked mole-rats and humans, which suggests that there may be a direct link between these networks and the longevity of these species, both of which would be expected to have much shorter lives based on their body mass.”

The Science Behind the Roundup Lawsuit

The decision will almost certainly be appealed, and is being widely criticized because it is not in line with the science. There is a long history of juries awarded damages based on flimsy science. Dow Corning famously filed for bankruptcy following class action law suits for alleged damages due to silicone breast implants, while the science was still preliminary. The claim was that the breast implants were causing auto-immune disease, which the manufacturer denied. Juries found the women sympathetic, however, and companies rarely appear sympathetic in such trials. But in 2000 a meta-analysis found:

On the basis of our meta-analyses, there was no evidence of an association between breast implants in general, or silicone-gel-filled breast implants specifically, and any of the individual connective-tissue diseases, all definite connective-tissue diseases combined, or other autoimmune or rheumatic conditions. From a public health perspective, breast implants appear to have a minimal effect on the number of women in whom connective-tissue diseases develop, and the elimination of implants would not be likely to reduce the incidence of connective-tissue diseases.

It seems we have a similar situation with Roundup and cancer, except the meta-analysis was published before the huge jury award, rather than after. The wrinkle here is that this and other lawsuits were likely sparked in part by the WHO decision in 2015 to classify glyphosate as a “probable carcinogen”. That decision was an outlier, however, and was immediately criticized. Several independent reviews of the WHO decision concluded that the decision was in error, and that the totality of evidence does not support the conclusion that there is any link between glyphosate and non-Hodgkins lymphoma specifically, or any cancer. I review the evidence and the expert panel reviews here.

An interesting 2017 review explored why the European Union (which concluded glyphosate was safe) came to a different conclusion than the WHO:

Use of different data sets, particularly on long-term toxicity/carcinogenicity in rodents, could partially explain the divergent views; but methodological differences in the evaluation of the available evidence have been identified. The EU assessment did not identify a carcinogenicity hazard, revised the toxicological profile proposing new toxicological reference values, and conducted a risk assessment for some representatives uses.

Essentially they used different data and methods. There is also this:

In a Special Report published on June 14, 2017, investigators at Reuters uncovered the shocking fact that an American scientist, Dr. Aaron Blair, the Chairman of the International Agency for Research on Cancer’s (IARC) Monograph 112 on glyphosate, suppressed critically important science.

The hidden science in question is recent data from the Agricultural Health Study (AHS), the largest and most comprehensive study ever conducted on pesticide exposure in humans. Evidence shows that Dr. Blair withheld updated data from the study which evaluates the pesticide exposure of more than 50,000 farmers and their families. The updated data reinforces the study’s original conclusion in 2005 that there is no evidence linking glyphosate exposure to cancer incidence.

So the best data we have shows no link between glyphosate and cancer, but that data was ignored by Dr. Blair. Further, Blair was involved with this study, and so definitely knew this data existed. Also, under oath Dr. Blair admitted: “[the] data would have altered IARC’s analysis.”

We are now, in part, seeing the fallout from this bad decision by the IARC.

According to reports of the case, Johnson’s attorney had to overcome the actual science showing glyphosate is safe and not associated with cancer. He did this by claiming that Roundup as a whole may cause cancer, even though glyphosate alone does not. While not impossible, this is an implausible claim that is still lacking in evidence. This was an act of simply moving the goalpost to avoid the more definitive scientific evidence. The ploy worked.

Johnson is also claiming that he had two accidental exposed to Roundup, so he was exposed to far more than would be the case with normal use. However, the time between exposure and his development of NHL was probably far too short for a causal relationship – a fact apparently not considered compelling by the jury.

Why should we all care about this? I of course have sympathy for Mr. Johnson, just as I have sympathy for all of those women who developed autoimmune diseases after getting silicone breast implants. I also think it is extremely important to hold corporations accountable if they cause harm due to their products. But justice in these cases will only prevail if the science prevails.

Further, glyphosate is demonstrably far less toxic than the alternative herbicides. If glyphosate is banned, or rendered unusable because of unfair lawsuits and unscientific jury verdicts, an important agricultural option will be eliminated – not because of science or because it’s the right thing, but out of fear and ignorance.

Reasonable people can argue and disagree about the optimal role of glyphosate and other herbicides in agriculture, and that is not the point of this article. But agricultural decisions should be based on a consensus view of the science, not the emotions of 12 jurors who clearly wanted to punish Monsanto regardless of what the science says.

This and other decisions also point to a flaw in our legal system. This is a much longer discussion outside the scope of this article, but the rules on the admissibility and role of scientific evidence in the courtroom still leave much to be desired in my opinion. Ultimately this case turned on an evaluation of a scientific claim, and I don’t see why such scientific questions should be decided by non-expert jurors.

Psychologist to explore how brain remembers precise information

A person’s general intelligence and ability to understand language are reliant on the brain’s ability to maintain precise information acquired over a short period of time.

To understand how these types of natural vision and cognitive functions are achieved in both healthy populations and individuals at high risk for psychosis, Weiwei Zhang, an assistant professor of psychology at UC Riverside, will assess how the brain’s hippocampus, a deep structure believed to be an exclusive hub for long-term memory, supports encoding, maintaining, and accessing precise short-term and long-term memories.

An expert on visual attention, working memory, and cognitive modeling, Zhang has received a five-year, $1.4 million grant from the National Institute of Mental Health, a division of the National Institutes of Health, to conduct the research.

“We will use functional neuroimaging to investigate whether the hippocampus in human participants shows an increase in neural activities when we try to remember ongoing events as accurately and precisely as possible,” said Zhang, the grant’s principal investigator. “This project will provide a clearer understanding of the functional limitations in working memory and establish the basic science backbone for future practice designed to understand and treat cognitive dysfunction in schizophrenia spectrum disorders and foggy memory in aging and other clinical populations.”

Zhang said the brain’s maintenance of information over a short period of time in working memory is pivotal for observers’ efficient interaction with exceedingly rich environmental content for both lower-level perception, such as maintaining relevant information across eye movements, and higher-level cognitive functions, including general intelligence and decision making.

Research in the past several decades on working memory and its deficits in various clinical populations has emphasized the quantitative aspect of working memory—how much information can be retained — and the corresponding neural mechanisms, he added.

“But only until recently has research begun to establish the theoretical and translational significance of the qualitative aspect of information maintained in working memory—that is, how precise is our memory,” he said. “We will investigate the process and circuitry that support representing and retaining precise information in working memory.”

His lab will use a combination of novel behavioral paradigms, individual differences, noninvasive brain stimulation, and functional magnetic resonance imaging to conduct the research.

In this field of research, memory has traditionally been partitioned into distinctive subsystems, including working memory and long-term memory. As such, the hippocampus and surrounding medial temporal lobe structures have been thought to jointly provide a hub exclusively for long-term memory, making them irrelevant for working memory.

“Our hypothesis postulates, however, that the hippocampus is essential for representing and retaining precise memories, regardless of whether they are in working memory or long-term memory,” Zhang said. “Our preliminary data have linked the hippocampus to memory precision, providing some support for our hypothesis.”

The grant, which began this month, will support a graduate student and a postdoctoral scholar. UC Irvine’s Michael A. Yassa, a professor of neurobiology and behavior, is a co-investigator on the grant. UCR’s Xiaoping Hu, a professor of bioengineering, Dr. Gerald Maguire, a professor of psychiatry and neuroscience, and Florida Atlantic University’s Edward Ester, an assistant professor of psychology, will serve as consultants.

“Most memory research conceptualizes memory as a storehouse for mental representations of past events,” Zhang said. “But as Steve Jobs put it once, ‘Quality is more important than quantity. One home run is much better than two doubles.’ Memory researchers such as myself also care about memory quality.”

Smartphone use may affect loneliness in mothers of young children

Mothers who spend an average of 1-2 hours per day on their smartphones may feel less lonely than those who use their phones for shorter or longer periods of time, according to a study involving 523 Japanese mothers published in the open access journal BMC Woman’s Health.

Researchers at Kyoto University, Japan found that mothers who used their smartphones less than one hour per day, or not at all, reported higher levels of loneliness, as did mothers who used their smartphones 2-3 hours per day or longer. No association was found between smartphone use of 1-2 hours and higher levels of loneliness, which suggests that 1-2 hours per day may be the optimal time for young mothers to spend on their smartphones. This may also be linked to social media use.

The corresponding author Marie Mandai said: “In Japan, women with children are generally considered to be surrounded by friends and family and therefore less likely to experience loneliness. However, recently there have been concerns about loneliness in mothers raising young children. This is the first study to report on use of communication devices and social media as factors affecting loneliness among mothers raising children under the age of three.”

The authors found that mothers who used their smartphones for longer periods of time also used social media more frequently, which may indicate that the use of social media may affect perceptions of loneliness, as social media was also named as a source of information for mothers.

The authors suggest that social networking sites may be a way of addressing loneliness among – and providing information to – mothers raising young children.

The authors analysed data from a questionnaire completed by 523 mothers raising children under the age of three in Nagahama City, Japan. The survey included questions on basic characteristics such as age, marital status, education level and number of children; loneliness; social networks (both online and offline); and types of communication devices and information sources used.

The authors caution that the generalizability of the results may be limited as data was collected in only one city in Japan. Furthermore, the cross-sectional, observational nature of the study and its reliance of self-reported data mean that it does not allow for conclusions about causality between smartphone use and lonelines

Biolin Scientific announces Nanoscience Instruments as distribution partner to expand the business in North America

Biolin Scientific AB announces today that it has appointed  Nanoscience Instruments, Inc as its distribution partner in North America. The agreement involves the distribution of QSense, Attension (only U.S. market)* and KSV NIMA instruments. Under the agreement, Nanoscience Instruments will also become the primary provider of service and application support in the U.S. & Canada.

Nanoscience Instruments sells and supports a wide variety of analytical solutions to academia and industry. Nanoscience Instruments specializes in surface science and nanoscale microscopy instrumentation, including benchtop SEMs, sample preparation for SEM and TEM, optical metrology, micro and nanomechanical characterization, electrospinning and electrospraying manufacturing, as well as consumables and accessories for these instruments.

“With Nanoscience instruments as our distributor partner, we strengthen our position and presence in the U.S. surface science market”, says Johan Westman, CEO of Biolin Scientific. “Expanding our network of sales, support personnel and application specialists will enable our customers to benefit from increased service levels and more customers to benefit from our innovative solutions.”

“We’re proud that Biolin Scientific has chosen us to be their distribution partner in the U.S. The cutting edge line of instrumentation aligns with our numerous industrial, academic and government customers”, says Sebastian Kossek, co-owner of Nanoscience Instruments. “This is an important partnership that will strengthen and expand scientific research in the US and Canada.”

“Service and support are the cornerstones of Nanoscience Instruments”, says Mark Flowers, co-owner of Nanoscience Instruments. “We look forward to extending our support to existing Biolin Scientific customers in the US and Canada.”

For more information, please contact Johan Westman, CEO at Biolin Scientific AB.

*In Canada, the Attension products will continue to be distributed by Spectra Research Corporation.

Baltimore Climate Suit Reaffirms Fossil Fuel Giants Can No Longer Ignore Communities Suffering From Damage Their Products Produced

Statement by Ken Kimmell, Union of Concerned Scientists

WASHINGTON (July 20, 2018)—Baltimore today sued 26 major fossil fuel companies in a Maryland state court for climate damages. The city joins cities and counties in California, Colorado and Washington state as well as New York City and Rhode Island, bringing the number of U.S. jurisdictions now seeking funding to adapt to climate change to 15.

Baltimore’s lawsuit charges that climate change driven by burning fossil fuels has caused and will continue to cause more frequent and severe heat waves, droughts and precipitation, which have already been linked to heat stroke, respiratory diseases and other serious health problems.

Below is a statement by Ken Kimmell, president of the Union of Concerned Scientists (UCS).

“As sea levels rise, so will communities’ efforts to protect their homes and livelihoods. According to a recent UCS analysis, Baltimore residents can expect accelerating sea level rise that by the end of the century will threaten some 2,400 homes that currently represent roughly $17 million in local property taxes.

“These impacts will ripple far beyond property values. Nearly a quarter of Baltimore residents currently live below the poverty line. Poverty and such climate-related threats as coastal flooding intersect to create hotspots of heightened risk. And people living in these communities that stand to lose the most have the least amount of resources to adapt or relocate to safer areas.

“For decades fossil fuel companies have tried to discredit climate science and block climate policies and renewable energy technologies that could have prevented this crisis. Baltimore’s lawsuit reaffirms that fossil fuel companies can no longer ignore communities suffering from the damage their products produced.”

The Union of Concerned Scientists puts rigorous, independent science to work to solve our planet’s most pressing problems. Joining with people across the country, we combine technical analysis and effective advocacy to create innovative, practical solutions for a healthy, safe, and sustainable future.

Mental health of young adults with lesbian parents is same as their peers

New findings from the 32-year U.S. National Longitudinal Lesbian Study, published in The New England Journal of Medicine

The longest-running prospective study on sexual minority parent families found that 25-year-olds raised by lesbian parents do as well on multiple measures of psychological health as adults from a population-based sample. The researchers compared relationships, educational/job performance, and behavioral, emotional and mental health problems in the two samples.

The 25-year-olds are participants in the ongoing U.S. National Longitudinal Lesbian Family Study (NLLFS), which has followed this cohort of offspring from conception to adulthood. The NLLFS, now in its 32nd year, has a 92 percent retention rate. This is the first NLLFS report based on data collected when the offspring were legal adults.

“When I began this study in 1986, there was considerable speculation about the future mental health of children conceived through donor insemination and raised by sexual minority parents,” said lead author Nanette Gartrell, M.D., Visiting Distinguished Scholar at the Williams Institute at UCLA School of Law. “We have followed these families since the mothers were inseminating or pregnant and now find that their 25-year-old daughters and sons score as well on mental health as other adults of the same age.”

The study focused on mental health because the peak incidence of many psychiatric disorders occurs during young adulthood. The researchers matched the 77 adult offspring in the NLLFS with a population-based sample of 77 adults of comparable age, sex, race/ethnicity and education to examine any disparities in their mental health.

The researchers specifically assessed adaptive functioning, the presence of behavioral or emotional problems, scores on the mental health diagnostic scales, and percentages of scores in the borderline or clinical range. Results showed no significant difference between the two groups for any of the measures.

“These findings demonstrate that claims that it is harmful for children to be raised by same-sex couples are completely unfounded,” said co-author Henny Bos, Ph.D., Professor of Child Development and Education, and Endowed Chair in Sexual and Gender Diversity in Families and Youth at the University of Amsterdam. “There is no justification to restrict child custody or placement, or access to reproductive technologies, based on the parents’ sexual orientation.”

There are an estimated 114,000 same-sex couples raising children in the United States, including 86,000 female couples. Ten states, including Alabama, Kansas, Michigan, Mississippi, North Dakota, Oklahoma, South Carolina, South Dakota, Texas, Virginia, allow state-licensed child welfare agencies to refuse to place and provide services to children and families if it conflicts with their religious beliefs.

This is the 23rd publication from data collected in the NLLFS. Previous research found that the development of psychological well-being in these offspring over a 7-year period from childhood through adolescence was the same for those conceived through known or unknown sperm donors. In addition, the absence of male role models did not adversely affect the psychological adjustment of 17-year-olds raised in lesbian households. None of these 17-year-olds had been abused by a parent or caregiver. In contrast, 26 percent of 17-year-olds nationally report physical abuse and 8 percent report sexual abuse by a parent or caregiver.

The report, “National Longitudinal Lesbian Family Study—Mental Health of Adult Offspring,” appears in The New England Journal of Medicine and is co-authored by Nanette Gartrell, M.D., Visiting Distinguished Scholar, along with Henny Bos, Ph.D., former Visiting International Scholar at the Williams Institute, and Audrey Koh, M.D., Associate Professor, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco.

Explosive Volcanoes Spawned Mysterious Martian Rock Formation

The results of a new study show Mars’s Medusae Fossae Formation is the largest known explosive volcanic deposit in the solar system.

Explosive volcanic eruptions that shot jets of hot ash, rock and gas skyward are the likely source of a mysterious Martian rock formation, a new study finds. The new finding could add to scientists’ understanding of Mars’s interior and its past potential for habitability, according to the study’s authors.

The Medusae Fossae Formation is a massive, unusual deposit of soft rock near Mars’s equator, with undulating hills and abrupt mesas. Scientists first observed the Medusae Fossae with NASA’s Mariner spacecraft in the 1960s but were perplexed as to how it formed.

Now, new research suggests the formation was deposited during explosive volcanic eruptions on the Red Planet more than 3 billion years ago. The formation is about one-fifth as large as the continental United States and 100 times more massive than the largest explosive volcanic deposit on Earth, making it the largest known explosive volcanic deposit in the solar system, according to the study’s authors.

“This is a massive deposit, not only on a Martian scale, but also in terms of the solar system, because we do not know of any other deposit that is like this,” said Lujendra Ojha, a planetary scientist at Johns Hopkins University in Baltimore and lead author of the new study published in the Journal of Geophysical Research: Planets, a journal of the American Geophysical Union.

Medusa Fossae Formation compared to Fish Canyon Tuff
This graphic shows the relative size of the Medusae Fossae Formation compared to Fish Canyon Tuff, the largest explosive volcanic deposit on Earth. The Medusae Fossae has an area of about 2 million square kilometers, which is roughly one-fifth the size of the continental United States. Fish Canyon Tuff, when it was deposited, covered an area of about 30,000 square kilometers, roughly the size of the state of Maryland. Credit: AGU.

Formation of the Medusae Fossae would have marked a pivotal point in Mars’s history, according to the study’s authors. The eruptions that created the deposit could have spewed massive amounts of climate-altering gases into Mars’s atmosphere and ejected enough water to cover Mars in a global ocean more than 9 centimeters (4 inches) thick, Ojha said.

Greenhouse gases exhaled during the eruptions that spawned the Medusae Fossae could have warmed Mars’s surface enough for water to remain liquid at its surface, but toxic volcanic gases like hydrogen sulfide and sulfur dioxide would have altered the chemistry of Mars’s surface and atmosphere. Both processes would have affected Mars’s potential for habitability, Ojha said.

Determining the Source of the Rock

The Medusae Fossae Formation consists of hills and mounds of sedimentary rock straddling Mars’s equator. Sedimentary rock forms when rock dust and debris accumulate on a planet’s surface and cement over time. Scientists have known about the Medusae Fossae for decades, but were unsure whether wind, water, ice or volcanic eruptions deposited rock debris in that location.

Global geographic map of Mars
A global geographic map of Mars, with the location of the Medusae Fossae Formation circled in red. Click image for larger version. Credit: MazzyBor, CC BY-SA 4.0 via Wikimedia Commons

Previous radar measurements of Mars’s surface suggested the Medusae Fossae had an unusual composition, but scientists were unable to determine whether it was made of highly porous rock or a mixture of rock and ice. In the new study, Ojha and a colleague used gravity data from various Mars orbiter spacecraft to measure the Medusae Fossae’s density for the first time. They found the rock is unusually porous: it’s about two-thirds as dense as the rest of the Martian crust. They also used radar and gravity data in combination to show the Medusae Fossae’s density cannot be explained by the presence of ice, which is much less dense than rock.

Because the rock is so porous, it had to have been deposited by explosive volcanic eruptions, according to the researchers. Volcanoes erupt in part because gases like carbon dioxide and water vapor dissolved in magma force the molten rock to rise to the surface. Magma containing lots of gas explodes skyward, shooting jets of ash and rock into the atmosphere.

Crater near Medusa Fossae Formation
A 13-kilometer (8-mile) diameter crater being infilled by the Medusae Fossae Formation. Credit: High Resolution Stereo Camera/European Space Agency.

Ash from these explosions plummets to the ground and streams downhill. After enough time has passed, the ash cements into rock, and Ojha suspects this is what formed the Medusae Fossae. As much as half of the soft rock originally deposited during the eruptions has eroded away, leaving behind the hills and valleys seen in the Medusae Fossae today.

Understanding Mars’s Interior

The new findings suggest the Martian interior is more complex than scientists originally thought, according to Ojha. Scientists know Mars has some water and carbon dioxide in its crust that allow explosive volcanic eruptions to happen on its surface, but the planet’s interior would have needed massive amounts of volatile gases—substances that become gas at low temperatures— to create a deposit of this size, he said.

“If you were to distribute the Medusae Fossae globally, it would make a 9.7-meter (32-foot) thick layer.” Ojha said. “Given the sheer magnitude of this deposit, it really is incredible because it implies that the magma was not only rich in volatiles and also that it had to be volatile-rich for long periods of time.”

The new study shows the promise of gravity surveys in interpreting Mars’s rock record, according to Kevin Lewis, a planetary scientist at Johns Hopkins University and co-author of the new study. “Future gravity surveys could help distinguish between ice, sediments and igneous rocks in the upper crust of the planet,” Lewis said.