Four classes of planetary systems

Peer-Reviewed Publication

UNIVERSITY OF BERN

 

IMAGE: ARTIST IMPRESSION OF THE FOUR CLASSES OF PLANETARY SYSTEM ARCHITECTURE. A NEW ARCHITECTURE FRAMEWORK ALLOWS RESEARCHERS TO STUDY AN ENTIRE PLANETARY SYSTEM AT THE SYSTEMS LEVEL. IF THE SMALL PLANETS WITHIN A SYSTEM ARE CLOSE TO THE STAR AND MASSIVE PLANETS FURTHER AWAY, SUCH SYSTEMS HAVE ‘ORDERED’ ARCHITECTURE. CONVERSELY, IF THE MASS OF THE PLANETS IN A SYSTEM TENDS TO DECREASE WITH DISTANCE TO THE STAR THESE SYSTEMS ARE ‘ANTI-ORDERED’. IF ALL PLANETS IN A SYSTEM HAVE SIMILAR MASSES, THEN THE ARCHITECTURE OF THIS SYSTEM IS ‘SIMILAR’. ‘MIXED’ PLANETARY SYSTEMS ARE THOSE IN WHICH THE PLANETARY MASSES SHOW LARGE VARIATIONS. RESEARCH SUGGESTS THAT PLANETARY SYSTEMS WHICH HAVE THE SAME ARCHITECTURE CLASS HAVE COMMON FORMATION PATHWAYS. view more 

CREDIT: © NCCR PLANETS, ILLUSTRATION: TOBIAS STIERLI

In our solar system, everything seems to be in order: The smaller rocky planets, such as Venus, Earth or Mars, orbit relatively close to our star. The large gas and ice giants, such as Jupiter, Saturn or Neptune, on the other hand, move in wide orbits around the sun. In two studies published in the scientific journal Astronomy & Astrophysics, researchers from the Universities of Bern and Geneva and the National Centre of Competence in Research (NCCR) PlanetS show that our planetary system is quite unique in this respect.

Like peas in a pod

"More than a decade ago, astronomers noticed, based on observations with the then groundbreaking Kepler telescope, that planets in other systems usually resemble their respective neighbours in size and mass – like peas in a pod," says study lead author Lokesh Mishra, researcher at the University of Bern and Geneva, as well as the NCCR PlanetS. But for a long time it was unclear whether this finding was due to limitations of observational methods. "It was not possible to determine whether the planets in any individual system were similar enough to fall into the class of the ‘peas in a pod’ systems, or whether they were rather different – just like in our solar system," says Mishra.

Therefore, the researcher developed a framework to determine the differences and similarities between planets of the same systems. And in doing so, he discovered that there are not two, but four such system architectures.

Four classes of planetary systems

"We call these four classes 'similar', 'ordered', 'anti-ordered' and 'mixed'," says Mishra. Planetary systems in which the masses of neighbouring planets are similar to each other, have similar architecture. Ordered planetary systems are those, in which the mass of the planets tends to increase with distance from the star – just as in our solar system. If, on the other hand, the mass of the planets roughly decreases with distance from the star, researchers speak of an anti-ordered architecture of the system. And mixed architectures occur, when the planetary masses in a system vary greatly from planet to planet.

"This framework can also be applied to any other measurements, such as radius, density or water fractions," says study co-author Yann Alibert, Professor of Planetary Science at the University of Bern and the NCCR PlanetS. "Now, for the first time, we have a tool to study planetary systems as a whole and compare them with other systems."

The findings also raise questions: Which architecture is the most common? Which factors control the emergence of an architecture type? Which factors do not play a role? Some of these, the researchers can answer.

A bridge spanning billions of years

"Our results show that 'similar' planetary systems are the most common type of architecture. About eight out of ten planetary systems around stars visible in the night sky have a 'similar' architecture," says Mishra. "This also explains why evidence of this architecture was found in the first few months of the Kepler mission." What surprised the team was that the "ordered" architecture – the one that also includes the solar system – seems to be the rarest class.

According to Mishra, there are indications that both the mass of the gas and dust disk from which the planets emerge, as well as the abundance of heavy elements in the respective star play a role. "From rather small, low-mass disks and stars with few heavy elements, 'similar' planetary systems emerge. Large, massive disks with many heavy elements in the star give rise to more ordered and anti-ordered systems. Mixed systems emerge from medium-sized disks. Dynamic interactions between planets – such as collisions or ejections – influence the final architecture," Mishra explains.

"A remarkable aspect of these results is that it links the initial conditions of planetary and stellar formation to a measurable property: the system architecture. Billions of years of evolution lie in between them. For the first time, we have succeeded in bridging this huge temporal gap and making testable predictions. It will be exciting to see if they will hold up," Alibert concludes.

Artist impression of the four classes of planetary system architecture. A new architecture framework allows researchers to study an entire planetary system at the systems level. If the small planets within a system are close to the star and massive planets further away, such systems have ‘Ordered’ architecture. Conversely, if the mass of the planets in a system tends to decrease with distance to the star these systems are ‘Anti-Ordered’. If all planets in a system have similar masses, then the architecture of this system is ‘Similar’. ‘Mixed’ planetary systems are those in which the planetary masses show large variations. Research suggests that planetary systems which have the same architecture class have common formation pathways.

CREDIT

© NCCR PlanetS, Illustration: Tobias Stierli

Publication details:

L. Mishra, Y. Alibert, S. Udry, C. Mordasini, A framework for the architecture of exoplanetary systems. I. Four classes of planetary system architecture, Astronomy and Astrophysics, Accepted December 2022, https://www.aanda.org/component/article?access=doi&doi=10.1051/0004-6361/202243751

DOI: 10.1051/0004-6361/202243751

L. Mishra, Y. Alibert, S. Udry, C. Mordasini, A framework for the architecture of exoplanetary systems. II. Nature versus nurture: Emergent formation pathways of architecture classes, Astronomy and Astrophysics, Accepted December 2022, https://www.aanda.org/component/article?access=doi&doi=10.1051/0004-6361/202244705       

DOI: 10.1051/0004-6361/202244705

Research Highlight Article in Nature Astronomy:

Maltagliati, L. Finding order in planetary architectures. Nat Astron 7, 8 (20230), https://www.nature.com/articles/s41550-023-01895-0

DOI: 10.1038/s41550-023-01895-0

Bernese space exploration: With the world’s elite since the first moon landing When the second man, "Buzz" Aldrin, stepped out of the lunar module on July 21, 1969, the first task he did was to set up the Bernese Solar Wind Composition experiment (SWC) also known as the “solar wind sail” by planting it in the ground of the moon, even before the American flag. This experiment, which was planned, built and the results analyzed by Prof. Dr. Johannes Geiss and his team from the Physics Institute of the University of Bern, was the first great highlight in the history of Bernese space exploration. Ever since Bernese space exploration has been among the world’s elite, and the University of Bern has been participating in space missions of the major space organizations, such as ESA, NASA, and JAXA. With CHEOPS the University of Bern shares responsibility with ESA for a whole mission. In addition, Bernese researchers are among the world leaders when it comes to models and simulations of the formation and development of planets. The successful work of the Department of Space Research and Planetary Sciences (WP) from the Physics Institute of the University of Bern was consolidated by the foundation of a university competence center, the Center for Space and Habitability (CSH). The Swiss National Fund also awarded the University of Bern the National Center of Competence in Research (NCCR) PlanetS, which it manages together with the University of Geneva.

 

Exoplanets in Geneva: 25 years of expertise crowned by a Nobel Prize The first exoplanet was discovered in 1995 by two researchers from the University of Geneva, Michel Mayor and Didier Queloz, laureates of the 2019 Nobel Prize in Physics.  This discovery allowed the Department of Astronomy of the University of Geneva to be at the forefront of research in the field, with the construction and installation of HARPS on the ESO 3.6m telescope in La Silla in 2003. For two decades, this spectrograph was the most efficient in the world for determining the mass of exoplanets. However, HARPS was surpassed in 2018 by ESPRESSO, another spectrograph built in Geneva and installed on the Very Large Telescope (VLT) in Paranal, Chile. Switzerland has also been involved in space-based observations of exoplanets with the CHEOPS mission, the result of two national expertises: the space know-how of the University of Bern in collaboration with its Geneva counterpart, and the ground-based experience of the University of Geneva assisted by its colleague in the Swiss capital. These two scientific and technical skills have also made it possible to create the National Center of Competence in Research (NCCR) PlanetS.

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JOURNAL

Astronomy and Astrophysics

DOI

10.1051/0004-6361/202243751 

ARTICLE TITLE

A framework for the architecture of exoplanetary systems. I. Four classes of planetary system architecture

ARTICLE PUBLICATION DATE

14-Feb-2023

CSIC completes the first network of robotic telescopes present on the five continents

Spain becomes the first country in the world to lead a global network of autonomous observatories. The BOOTES network, with seven facilities, is a pioneer in space surveillance and the study of transient cosmic phenomena, which shine briefly, intensely

Reports and Proceedings

SPANISH NATIONAL RESEARCH COUNCIL (CSIC)

 

IMAGE: THE BOOTES-3 STATION IN THE SOUTH ISLAND IN NEW ZEALAND (IAA-CSIC/NIWA) view more 

CREDIT: IAA-CSIC/NIWA

“BOOTES is the result of almost twenty-five years of continuous effort, since we installed the first station in 1998 at INTA (Arenosillo, Huelva), the institution that initially supported the project. The complete deployment represents a scientific milestone since it is the first robotic network with a presence on all continents", according to Alberto J. Castro-Tirado, scientist at IAA-CSIC acting as Principal Investigator since the very beginning. This is ahead of the American project, whose Asian station is under construction, and the Russian one, which is lacking an installation in Oceania.

The BOOTES network is managed by the IAA-CSIC, with strong involvement of the University of Malaga and in collaboration with other Spanish and international institutions. Its main objective is to quickly and autonomously observe what are known as transient sources, astrophysical objects that do not present a permanent emission over time, but rather emit light briefly, intensely and suddenly. The detection of these events is usually done from satellite, and BOOTES provides an automated response in real time that allows their characterization.

The network will contribute to the study of gamma-ray bursts, which are the most energetic events in the universe and are associated with the death of very massive stars. Its detection usually occurs through satellites, which inform the scientific community of the outbreak so that the event can be studied in detail. The existence of a network of very fast pointing robotic telescopes such as BOOTES represents an ideal complement to satellite detection and, in fact, BOOTES will also work to track and monitor neutrino sources and objects that emit gravitational waves, or even objects such as comets, asteroids, variable stars or supernovae. But it will also keep an eye on the sky, both in tracking space debris and potentially dangerous objects that may pose a threat to our planet.

The seven stations of the BOOTES Global Network (bootes.iaa.es) are present in the five continents.

CREDIT

IAA-CSIC/UMA/INTAURNAL

High impact science with BOOTES

Fast-tracking observations of gamma-ray bursts with BOOTES, from the first few seconds to the final phases, have enabled narrowing models of gamma-ray bursts, and have also contributed to some high-impact results in recent years. One of the observatories of the BOOTES network was, for example, the only Spanish station that observed in 2017 the event known as GW170817, the first detection of a gravitational wave electromagnetic counterpart in history. The phenomenon responsible for this emission, the merger of two neutron stars, allowed the first simultaneous study in light and gravitational waves for the first time and inaugurated a new era in astronomical observations.

BOOTES contributed in 2020 to the identification of a very short duration radio burst-producing source in our own galaxy, the Milky Way, which was presented in three papers in Nature which suggested that a magnetar, a neutron star with a very intense magnetic field, would be behind this phenomenon.

In 2021, BOOTES also contributed to the research work published in Nature, of different pulses in the giant magnetic flare of a neutron star: in just a tenth of a second, a magnetar released an energy equivalent to that produced by the Sun in a hundred thousand years, and its detailed analysis revealed multiple pulses at the peak of the eruption, which shed light on these still little-known giant magnetic flares.

“The culmination of the network is a success, since it has been possible with a human team and a much lower budget than similar projects. With four stations in the northern hemisphere and three in the southern hemisphere, there will always be at least one telescope covering the northern and southern skies, making it extremely efficient in detecting transient sources. In addition, with all the stations already operational, we can coordinate them as a single observatory that covers the entire planet, the potential of which we will show to the international community at the robotic astrophysics congress that we hold biannually and that will take place in October in Malaga”, points out Castro-Tirado (IAA-CSIC). “I conceived the project when I was developing my doctoral thesis in Denmark thirty years ago, and for me it is a dream come true”, concludes the researcher.

Y.-D. Hu et al. The Burst Observer and Optical Transient Exploring System in the multi-messenger astronomy era. Frontiers in Astronomy (2023). DOI: 10.3389/fspas.2023.952887

A.J. Castro-Tirado et al. The Burst Observer and Optical Transient Exploring System (BOOTES). Astronomy and Astrophysics Supplement 138, 583 (1998). DOI: https://doi.org/10.1051/aas:1999362

The BOOTES-3 station in the South Island in New Zealand .

CREDIT

IAA-CSIC/NIWA

Frontiers in Astronomy and Space Sciences

DOI

10.3389/fspas.2023.952887 

ARTICLE TITLE

The Burst Observer and Optical Transient Exploring System in the multi-messenger astronomy era

Upsurge in rocket launches could impact the ozone layer

University of Canterbury (UC) researchers have summarised the threats that future rocket launches would pose to Earth’s protective ozone layer, in a new review article published in the Journal of the Royal Society of New Zealand.

Peer-Reviewed Publication

TAYLOR & FRANCIS GROUP

University of Canterbury (UC) researchers have summarised the threats that future rocket launches would pose to Earth’s protective ozone layer, in a new review article published in the Journal of the Royal Society of New Zealand.

The ozone layer, which protects life on Earth from harmful ultraviolet (UV) rays from the sun, was severely damaged in the 1980s and 1990s due to chlorofluorocarbons (CFCs) — chemicals used in aerosols and refrigeration. Thanks to coordinated global action and legislation, the ozone layer is now on track to heal this century.

Rocket launches emit both gases and particulates that damage the ozone layer. Reactive chlorine, black carbon, and nitrogen oxides (among other species) are all emitted by contemporary rockets. New fuels like methane are yet to be measured.

“The current impact of rocket launches on the ozone layer is estimated to be small but has the potential to grow as companies and nations scale up their space programmes,” Associate Professor in Environmental Physics Dr Laura Revell says.

“Ozone recovery has been a global success story. We want to ensure that future rocket launches continue that sustainable recovery.”

Global annual launches grew from 90 to 190 in the past 5 years, largely in the Northern Hemisphere. The space industry is projected to grow more rapidly: financial estimates indicate the global space industry could grow to US$3.7 trillion by 2040.

“Rockets are a perfect example of a ‘charismatic technology’ – where the promise of what the technology can enable drives deep emotional investment – extending far beyond what the technology also affects,” Rutherford Discovery Fellow and planetary scientist UC senior lecturer Dr Michele Bannister says.

Rocket fuel emissions are currently unregulated, both in Aotearoa New Zealand and internationally.

UC Master’s student Tyler Brown, who was involved in the research, says Aotearoa New Zealand is uniquely positioned to both lead and participate in this field. “New Zealand’s role as a major player in the global launch industry means we can help steer the conversation. We stand to benefit enormously from additional growth in our domestic space industry, and with that comes the opportunity to ensure that global activities are sustainable for the planet as a whole.”

The review lays out detailed plans of action for companies and for the ozone research community, with a call for coordinated global action to protect the upper atmosphere environment. Actions that companies can take include measuring the emissions of launch vehicles on the test stand and in-situ during flight, making that data available to researchers, and putting effects on ozone into industry best-practise rocket design and development.

“The international ozone research community has a strong history of measuring atmospheric ozone and developing models to understand how human activities could impact this critical layer of our atmosphere. By working with launch providers, we are well-placed to figure out what impacts we might see”, says Dr Revell.

“Rockets have exciting potential to enable industrial-level access to near-Earth space, and exploration throughout the Solar System. Creating sustainable global rocket launches is going to take coordination across aerospace companies, scientists, and governments: it is achievable, but we need to start now,” says Dr Bannister. “This is our chance to get ahead of the game.”

 

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JOURNAL

Journal of the Royal Society of New Zealand

DOI

10.1080/03036758.2022.2152467 

METHOD OF RESEARCH

Literature review

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Envisioning a sustainable future for space launches: a review of current research and policy

NOISE POLLUTION

The roar and crackle of Artemis 1

Measurements taken at locations around the launch pad revealed noise levels as high as 136 decibels from 1.5 km away

Peer-Reviewed Publication

AMERICAN INSTITUTE OF PHYSICS

 

IMAGE: AN ARRAY OF FOUR MICROPHONES READY FOR NOISE MEASUREMENTS. view more 

CREDIT: KENT GEE

WASHINGTON, Feb. 14, 2023 – When the Artemis 1 mission was launched by NASA’s Space Launch System, SLS, in November, it became the world’s most powerful rocket, exceeding the thrust of the previous record holder, Saturn , by 13%. With liftoff came a loud roar heard miles away.

In JASA Express Letters, published on behalf of the Acoustical Society of America by AIP Publishing, researchers from Brigham Young University and Rollins College in Florida reported noise measurements during the launch at different locations around Kennedy Space Center.

The data collected can be used to validate existing noise prediction models, which are needed to protect equipment as well as the surrounding environment and community. These data will be useful as more powerful lift vehicles, including the SLS series, are developed.

“We hope these early results will help prevent the spread of possible misinformation, as happened with the Saturn 5,” author Kent Gee said. “Numerous websites and discussion forums suggested sound levels that were far too high, with inaccurate reports of the Saturn 5’s sound waves melting concrete and causing grass fires.”

The combination of nighttime darkness, humidity, and backlighting provided a rare opportunity to view propagating pressure waves, which can be seen in the accompanying video.

Artemis 1 was launched with four liquid hydrogen-oxygen engines plus two solid-fuel rocket boosters (SRBs). According to the authors, the SRBs are likely the dominant noise source during liftoff.

The investigators studied recordings at microphones located 1.5 km to 5.2 km from the launch pad. All stations were outside the blast danger area. Maximum noise levels at all five stations exceeded those predicted in a preliminary assessment.

At 1.5 km from the pad, the maximum noise level reached 136 decibels. At a 5.2 km distance, the noise was 129 decibels, nearly 20 decibels higher than predicted by a prelaunch noise model.

“This suggests a need to revisit and probably revise those models,” author Grant Hart said.

A procedure known as A-weighting is often used to assess the impact of noise on humans. Because we don’t hear as well in some frequency ranges as others, a filter is applied to emphasize the sounds we do hear. Using this method, the investigators found noise levels at 5.2 km from the launchpad were about as loud as a chainsaw.

A characteristic feature of rocket launches is a crackling sound from shock waves. These shocks represent instantaneous sound pressure increases that are much louder than crackling noises encountered in everyday life.

Author Whitney Coyle said, “We found the Artemis 1 noise level at 5 km had a crackling quality about 40 million times greater than a bowl of Rice Krispies.”

“Although this study is an important step forward, we still have a long way to go to understand everything about the generation, propagation, and perception of rocket noise,” Gee said.

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The article “Space launch system acoustics: Far-field noise measurements of the Artemis-I launch” is authored by Kent L. Gee, Grant W. Hart, Carson F. Cunningham, Mark C. Anderson, Michael S. Bassett, Logan T. Mathews, J. Taggart Durrant, Levi T. Moats, Whitney L. Coyle, Makayle S. Kellison, and Margaret J. Kuffskie. It will appear in JASA Express Letters on Feb. 14, 2023 (DOI: 10.1121/10.0016878). After that date, it can be accessed at https://doi.org/10.1121/10.0016878.

Researchers gather in front of SLS rocket prior to launch.

CREDIT

Taggart Durrant

Time-synchronized compilation [VIDEO] | EurekAlert! Science News Releases

ABOUT THE JOURNAL

JASA Express Letters is a gold open-access journal devoted to the rapid and open dissemination of important new research results and technical discussion in all fields of acoustics. It serves physical scientists, life scientists, engineers, psychologists, physiologists, architects, musicians, and speech communication specialists who wish to quickly report the results of their acoustical research in letter-sized contributions. See https://asa.scitation.org/journal/jel.

ABOUT ACOUSTICAL SOCIETY OF AMERICA

The Acoustical Society of America (ASA) is the premier international scientific society in acoustics devoted to the science and technology of sound. Its 7,000 members worldwide represent a broad spectrum of the study of acoustics. ASA publications include The Journal of the Acoustical Society of America (the world's leading journal on acoustics), JASA Express Letters, Proceedings of Meetings on Acoustics, Acoustics Today magazine, books, and standards on acoustics. The society also holds two major scientific meetings each year. See https://acousticalsociety.org/.

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JOURNAL

JASA Express Letters

DOI

10.1121/10.0016878 

ARTICLE TITLE

Space launch system acoustics: Far-field noise measurements of the Artemis-I launch

ARTICLE PUBLICATION DATE

14-Feb-2023

Protecting bats with better wind turbine control

Peer-Reviewed Publication

DE GRUYTER

 

IMAGE: NYCTALUS LEISLERI, A MID-SIZED BAT, COMMONLY KNOWN AS THE LESSER NOCTULE view more 

CREDIT: COPYRIGHT: DINA RNJAK, GEONATURA LTD.

Bat fatalities caused by wind turbines could be significantly reduced by as much as 86% thanks to a new site-specific mitigation scheme described by researchers in a study in the journal Mammalia.

The spread of wind turbines, driven by the steady move away from fossil fuel energy sources, poses a significant threat to bats as many are killed each year by collisions with turbine blades.

While several mitigation systems have been tried over recent years, their efficiency in protecting bats has not been fully investigated. One method, called blanket curtailment, slows blade rotation to less than one revolution per minute at the low wind speeds which have been found to cause the highest number of bat fatalities. This is still a relatively unsophisticated procedure since it usually involves applying a general wind speed threshold for all wind turbines for a longer period of time, and can cause considerable loss of energy generation.

To find a way to significantly reduce bat fatalities along with minimizing reduction in electricity production, lead author Dina Rnjak of Geonatura Ltd. and colleagues carried out a four-year monitoring programme at Rudine wind farm, Croatia.

During the first two years, the high number of bat carcasses found from mid-July to the end of October indicated a clear need for some mitigation strategy at that time of year. In addition to the known importance of wind speed, the study also confirmed the significant role of temperature and rainfall on bat activity, which was reduced during periods of rain and at temperatures below 11°C.

The direct monitoring of bat activity, fatalities and the effect of weather led to a site-specific wind turbine curtailment strategy dependent on the specific wind-speed range most dangerous for the bats, adapted to the most critical time periods and most significantly located wind turbines. In addition, the strategy included a process called blade feathering, which adjusts the angle of the turbine blade to prevent undesirable freewheeling. The overall effectiveness of this approach was confirmed in trials conducted over two years.

Using the same method at another wind farm in Croatia showed that different critical wind speed thresholds needed to be applied at that site to achieve a significant reduction in fatalities.

“This indicates the importance of using site-specific data to determine the best mitigation scheme for each location,” said Rnjak. “Our work shows that electricity production losses can be significantly reduced by replacing blanket curtailment with more adaptable and site-specific approaches.”

The researchers now plan to continue to refine these methods and engage in publicity to encourage them to be more widely applied.

The open access article can be found here: https://doi.org/10.1515/mammalia-2022-0100

Rudine wind farm, Croatia, location of the case study

CREDIT

Dina Rnjak, Geonatura Ltd.

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JOURNAL

Mammalia

DOI

10.1515/mammalia-2022-0100 

METHOD OF RESEARCH

Case study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Reducing bat mortality at wind farms using site-specific mitigation measures: a case study in the Mediterranean region, Croatia

ARTICLE PUBLICATION DATE

13-Feb-2023

Kangaroo fecal microbes could reduce methane from cows

Peer-Reviewed Publication

WASHINGTON STATE UNIVERSITY

RICHLAND, Wash. – Baby kangaroo feces might help provide an unlikely solution to the environmental problem of cow-produced methane. A microbial culture developed from the kangaroo feces inhibited methane production in a cow stomach simulator in a Washington State University study.

After researchers added the baby kangaroo culture and a known methane inhibitor to the simulated stomach, it produced acetic acid instead of methane. Unlike methane, which cattle discard as flatulence, acetic acid has benefits for cows as it aids muscle growth. The researchers published their work in the journal Biocatalysis and Agricultural Biotechnology.

“Methane emissions from cows are a major contributor to greenhouse gases, and at the same time, people like to eat red meat,” said Birgitte Ahring, corresponding author on the paper and a professor in with the Bioproducts, Sciences and Engineering Laboratory at the WSU Tri-Cities campus. “We have to find a way to mitigate this problem.”

Reducing the burps and farts of methane emissions from cattle is no laughing matter. Methane is the second largest greenhouse gas contributor and is about 30 times more potent at heating up the atmosphere than carbon dioxide. More than half of the methane released to the atmosphere is thought to come from the agricultural sector, and ruminant animals, such as cattle and goats, are the most significant contributors. Furthermore, the process of producing methane requires as much as 10% of the animal’s energy.

Researchers have tried changing cows’ diets as well as giving them chemical inhibitors to stop methane production, but the methane-producing bacteria soon become resistant to the chemicals. They also have tried to develop vaccines, but a cow’s microbiome depends on where it’s eating, and there are far too many varieties of the methane-producing bacteria worldwide. The interventions can also negatively affect the animals’ biological processes.

The WSU researchers study fermentation and anaerobic processes and had previously designed an artificial rumen, the largest stomach compartment found in ruminant animals, to simulate cow digestion. With many enzymes that are able to break down natural materials, rumens have “amazing abilities,” said Ahring, who is also a professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering and in Biological System Engineering.  

Looking to investigate how to outcompete the methane-producing bacteria in their reactor, Ahring learned that kangaroos have acetic acid-producing, instead of methane-producing, bacteria in their foregut. Her students tracked down some kangaroos, took samples and learned that the specialized acetic acid-producing process only occurred in baby kangaroos – not in adults. Unable to separate out specific bacteria that might be producing the acetic acid, the researchers used a stable mixed culture developed from the feces of the baby kangaroo.

After initially reducing the methane-producing bacteria in their reactor with a specialized chemical, the acetic acid bacteria were able to replace the methane-producing microbes for several months with a similar growth rate as the methane-producing microbes.

While the researchers have tested their system in the simulated rumen, they hope to try it on real cows sometime in the future.

“It is a very good culture. I have no doubt it is promising,” Ahring said. “It could be really interesting to see if that culture could run for an extended period of time, so we would only have to inhibit the methane production from time to time. Then, it could actually be a practice.”

The work was supported by WSU’s College of Agricultural, Human, and Natural Resource Sciences’ Appendix A program.

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JOURNAL

Biocatalysis and Agricultural Biotechnology

DOI

10.1016/j.bcab.2022.102526 

ARTICLE TITLE

Reducing methane production from rumen cultures by bioaugmentation with homoacetogenic bacteria

Let’s talk to a moth about sex: Polish chemists have 'made a deal' with a butterfly threatening pine forests

Peer-Reviewed Publication

INSTITUTE OF PHYSICAL CHEMISTRY OF THE POLISH ACADEMY OF SCIENCES

 

IMAGE: A DENDROLIMUS PINI, L. IS A HUNGRY BEAST HIDING IN FORESTS. THE ENLIGHTENED PROF. RAFAŁ SZMIGIELSKI FOUND A WAY TO FACE IT. THE PHOTO WAS TAKEN IN THE BOOKSTORE WRZENIE ŚWIATA. PHOTO: GRZEGORZ KRZYZEWSKI view more 

CREDIT: SOURCE IPC PAS, GRZEGORZ KRZYZEWSKI

Beyond the seven mountains and forests, a hungry beast was stealing away. Does this sound like a fairy tale? In reality, such a beast does exist. It is the caterpillar of the nocturnal pine-tree lappet moth (Dendrolimus pini, L.), which feeds on pine needles and wreaks havoc in the forests on a massive scale. However, words of love between these night butterflies may be the key to preventing outbreaks of their terrifying hunger. Monitoring the population of D. pini and its control has been possible thanks to the recent discovery of a team of scientists from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) led by Prof. Rafał Szmigielski. They have deciphered the chemical hieroglyphs of the moth's language by which females attract males, finding a way to deal with the voracious beast and save the pine forests. Let's take a closer look at their discovery.

 

The voracious caterpillars of the pine-tree lappet Dendrolimus pini can destroy tens of thousands of hectares of coniferous forests. Despite the lack of ecological solutions to effectively combat this insect, we will not be saying goodbye to our pine trees. Scientists from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) have found a way towards effective protection against the lappet moth. They have deciphered the chemical 'love words' by which female Dendrolimus pini moths attract their males. A new pheromone blend based, among others, on newly discovered biocomponents of the sex pheromone of the voracious insect developed by scientists from the IPC PAS may serve as an effective tool for monitoring and, in the long term, also for controlling the abundance of pine-tree lappet moth in our forests.

 

The pine-tree lappet moth Dendrolimus pini, a moth with a stocky body and grey-brown coloration, is one of Poland's most giant nocturnal butterflies. After overwintering in the mulch, the caterpillars of this butterfly climb into the crowns of pine trees, where they busily devour the needles. As up to several hundred perpetually hungry caterpillars can feed on a single tree, a rapid increase in the Dendrolimus pini population can lead to the extermination of large forest areas. Without ecological and efficient tools for controlling the moth’s population, the data on their population growth is crucial. However, synthetic pheromone traps used by foresters to attract Dendrolimus pini males were found to be insufficient. In the project carried out by scientists from the IPC PAS in collaboration with the Institute of Forestry Research (IBL), a novel and far more effective sex pheromone lure for the pine-tree moth has been developed.

 

The research into the pine-tree lappet moth's chemical love language proved more difficult than scientists had anticipated for entirely surprising reasons. The study began by the identifying the pheromones' components secreted by young Dendrolimus pini females. To develop a preparation to attract the voracious males, all the chemical compounds that are components of the sexual pheromone were put under the microscope. Interestingly, in addition to the previously known chemical compounds, the secreted 'pheromone perfume' was found to contain other components, including - compounds derived from Scot’s pine needles and other organic compounds hitherto undiscovered, either significantly influencing the behavior of the caterpillars. The captured substances were chromatographically separated into single components and subjected to a detailed chemical analysis using tandem mass spectrometry. The comparison of the molecular structures of the identified Dendrolimus pini sex pheromone components with the composition of a commercially available product strengthened the researchers' conviction that one of the most important reasons for the pine-tree lappet moths' poor response to the synthetic pheromone was its oversimplified chemical composition and the lack of key bioactive components.

 

"We aimed to identify all the substances in the pheromones secreted by the Dendrolimus pini moth and to create a unique formulation to divert the lappet moth's attention from the conifers, including the Scot’s pine trees. And all this to save the forests from Dendrolimus pini hunger," says Prof. Rafał Szmigielski.

 

Based on the results of detailed analyses, chemists from the IPC PAS designed new formulations of the pheromone mixtures, which were subjected to numerous tests in a laboratory framework using modern bioanalytical techniques, such as wind tunnel, olfactometry, and electroanthenography, and then in the field measurements. Dendrolimus pini moths were placed in wind tunnels exposed to specific chemicals and self-built terraria to test behavior in the natural environment. Hundreds of experiments were carried out with female and male butterflies in this way, exposing them to various compounds. The scientists looked at (Z5)-dodecanal, abbreviated as (Z5)-12:Ald, which occurs naturally in pine needles and attracts caterpillars, and (Z5)-decen-1-yl acetate, known as (Z5)-10:OAc, which in turn discourages them. Studies have shown the critical role of these two compounds on barnacle behaviour.

 

"The mixture of chemical compounds we have identified and patented can - naturally with appropriate conventionality - be treated as certain words of non-trivial structure, spoken in the chemical language of the moth. The main accent here is on two 'sounds,' one of which people pronounce differently from the other. For this chemical ''I love you'' to sound convincing, additional words are needed to increase the carrying capacity of the main message, such as plant-derived compounds,” – explains Prof. Rafał Szmigielski.

 

Previous attempts attracted a maximum of a few dozen pine barnacle males per trap over several weeks to pheromone traps. Meanwhile, chemical calling using a mixture of substances developed by a group from the IPC PAS increased this number to as high as 160 males per trap in just 3-4 days. Foresters unanimously considered such an increase in insect interest to be a huge success, bringing us closer to saving the pine forests from the appetite of these voracious insects.

 

Identifying new components of the sex pheromone emitted by the female moth Dendrolimus pini and their correlation with the specific behavior of this tiny insect is a step forward toward the effective protection of pine forests. The scientists' research into creating the synthetic pheromone lures is also more than just monitoring the moth's behavior. It is, first and foremost, the interdisciplinary work, a love of nature, and the fascinating the micro-world.

 

This work received financing from the National Centre for Research and Development (contract PBS2/A9/25/2013).

SCIENTIFIC PAPERS:

Rudziński KJ, Staszek D, Asztemborska M, Sukovata L, Raczko J, Cieślak M, Kolk A, Szmigielski R.

Newly Discovered Components of Dendrolimus pini Sex Pheromone.

Insects. 2022; 13(11):1063

https://doi.org/10.3390/insects13111063

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JOURNAL

Insects

DOI

10.3390/insects13111063