Sunday, July 11, 2021

Defending Earth: Repurposing telecommunication satellites to protect Earth from asteroid collision

Written By: Moohita Kaur Garg WION Web Team
New Delhi, India Published: Jul 11, 2021

An asteroid (representative image) Photograph:( AFP )

Researchers at the European Space Agency are studying how to prepare for an apocalyptic event similar to dinosaurs' end

A recent study conducted by the European aerospace company Airbus suggests that when an asteroid is hurtling toward our planets, we could deploy large TV broadcasting satellites to deflect the space rock.

The study is a part of the European Space Agency's efforts to prepare for a possible apocalyptic event, similar to the one that wiped out dinosaurs.

Conducted under the mission concept codenamed FastKD or Fast Kinetic Deflection, it envisions using telecommunications satellites in particular, as these are placed in a geostationary orbit. This means that they are placed in such a way that their position looks stationary, as these satellites circle the Earth at a speed that matches the planet's speed of rotation.

Usually very large, on average, these weigh around 4 to 6 tonnes. This weight would aid in giving the object in question enough force to affect the trajectory of space rock.

However, according to Albert Falke, the lead researcher of this study, it would take around 10 such satellites to sufficiently change the trajectory of 300 meters or 1,000-foot wide asteroid.

But what about a Dinosaur extinction-size Asteroid?

Falke is hesitant to say whether an asteroid could still be deflected using this method if it is more than 1,000 feet (300 meters) in diameter.

Interestingly, the asteroid that led to the extinction of dinosaurs is believed to have been 9.6 kilometres or 6 miles in diameter.

Why telecommunication satellites?

This method does not require the invention and subsequent launch of a whole new device. Telecommunication satellites are available readily. In case astronomers were to detect an asteroid at a late stage, all that's required is to repurpose the satellites under construction and launch them within a short span of time.

The combined effort of multiple satellites could very well change the trajectory of the approaching object.

Changing its trajectory by just a few inches may not totally avert a disaster, but it could nudge it off course, enough to avert a catastrophe if done well enough in advance of an expected impact.

For telecommunication satellites to be capable of executing an earth-saving mission in orbit, special equipment is needed to enable communication in deep space, along with navigation, and guidance required to reach the asteroid.

Modules for this project still need to be developed. The ideal situation would be to build and test these systems in advance of an emergency and have them ready.

That said, the human species definitely has an advantage over dinosaurs.

NASA is set to conduct a mission called DART next year. The experiment will be the first-ever asteroid deflection experiment.

Rare 4.5 Billion-Year-Old Meteorite Could Hold Secrets to Life on Earth

TOPICS:Astrobiology Meteorites University Of Glasgow

By UNIVERSITY OF GLASGOW JULY 11, 2021

Image of the fireball in February 28, 2021. Credit: UK Meteor Observation Network

Scientists are set to uncover the secrets of a rare meteorite and possibly the origins of oceans and life on Earth, thanks to Science and Technology Facilities Council (STFC) funding.

Research carried out on the meteorite, which fell in the UK earlier this year, suggests that the space rock dates back to the beginning of the Solar System, 4.5 billion years ago.

The meteorite has now been officially classified, thanks in part to the STFC-funded studies on the sample.

The Winchcombe meteorite, aptly named after the Gloucestershire town where it landed, is an extremely rare type called a carbonaceous chondrite. It is a stony meteorite, rich in water and organic matter, which has retained its chemistry from the formation of the solar system. Initial analyses showing Winchcombe to be a member of the CM (“Mighei-like”) group of carbonaceous chondrites have now been formally approved by the Meteoritical Society.

STFC provided an urgency grant in order to help fund the work of planetary scientists across the UK. The funding has enabled the Natural History Museum to invest in state-of-the-art curation facilities to preserve the meteorite, and also supported time-sensitive mineralogical and organic analyses in specialist laboratories at several leading UK institutions.

An image of one of the fragments of the Winchcombe meteorite. Credit: Trustee of the Natural History Museum

Dr. Ashley King, a UK Research and Innovation (UKRI) Future Leaders Fellow in the Department of Earth Sciences at the Natural History Museum, said: “We are grateful for the funding STFC has provided. Winchcombe is the first meteorite fall to be recovered in the UK for 30 years and the first-ever carbonaceous chondrite to be recovered in our country. STFC’s funding is aiding us with this unique opportunity to discover the origins of water and life on Earth. Through the funding, we have been able to invest in state-of-the-art equipment that has contributed to our analysis and research into the Winchcombe meteorite.”

The meteorite was tracked using images and video footage from the UK Fireball Alliance (UKFAll), a collaboration between the UK’s meteor camera networks that includes the UK Fireball Network, which is funded by STFC. Fragments were then quickly located and recovered. Since the discovery, UK scientists have been studying Winchcombe to understand its mineralogy and chemistry to learn about how the Solar System formed.

Dr. Luke Daly from the University of Glasgow and co-lead of the UK Fireball Network, said: “Being able to investigate Winchcombe is a dream come true. Many of us have spent our entire careers studying this type of rare meteorite. We are also involved in JAXA’s Hayabusa2 and NASA’s OSIRIS-REx missions, which aim to return pristine samples of carbonaceous asteroids to the Earth. For a carbonaceous chondrite meteorite to fall in the UK, and for it to be recovered so quickly and have a known orbit, is a really special event and a fantastic opportunity for the UK planetary science community.”

Funding from STFC enabled scientists to quickly begin the search for signs of water and organics in Winchcombe before it could be contaminated by the terrestrial environment.

Dr. Queenie Chan from Royal Holloway, University of London added: “The teams preliminary analyses confirm that Winchcombe contains a wide range of organic material! Studying the meteorite only weeks after the fall, before any significant terrestrial contamination, means that we really are peering back in time at the ingredients present at the birth of the solar system, and learning about how they came together to make planets like the Earth.”

A piece of the Winchcombe meteorite that was recovered during an organized search by the UK planetary science community is now on public display at London’s Natural History Museum.

Chinese scientists' observation of Crab Nebula challenges classical theories
By Global Times

Published: Jul 10, 2021

China's Large High Altitude Air Shower Observatory (LHAASO) is pictured in Daocheng, southwest China's Sichuan Province on July 8, 2021. Based on the observations of China's LHAASO, one of the country's key national science and technology infrastructure facilities, Chinese scientists have measured the brightness of the standard candle in high-energy astronomy.Photo:Xinhua

China's Large High Altitude Air Shower Observatory (LHAASO) is pictured in Daocheng,

southwest China's Sichuan Province on July 6, 2021.Photo:Xinhua

China's Large High Altitude Air Shower Observatory (LHAASO) is pictured in Daocheng,

southwest China's Sichuan Province on July 6, 2021.Photo:Xinhua

Cao Zhen, chief scientist of China's Large High Altitude Air Shower Observatory (LHAASO),poses for a photo with the sand table of LHAASO at the Institute of High Energy Physics (IHEP)

under the Chinese Academy of Sciences (CAS), Feb. 23, 2021.Photo:Xinhua
Nearly 1,000 years after ancient Chinese stargazers discovered a supernova, Chinese scientists have made a new discovery challenging classical physical theories. Their observation of the Crab Nebula, the remnant of an exploding star, indicates it could contain a super-powerful electron accelerator.

The Crab Nebula, 6,500 light-years from Earth, was created in a bright supernova explosion in 1054 A.D. and recorded by the imperial astronomers of China's Northern Song Dynasty (960-1127). It is the first supernova remnant identified by modern astronomy that has a clear historical record.

The Crab Nebula is one of few sources that has been measured in all energy bands including radio, infrared, optical, ultraviolet, X-ray and gamma-ray. Its spectrum has been extensively studied for decades by many observers. As a bright and stable high-energy source, the Crab Nebula is regarded as the standard candle by scientists.

Based on the observations of China's Large High Altitude Air Shower Observatory (LHAASO), one of the country's key national science and technology infrastructure facilities, Chinese scientists have measured the brightness of the standard candle in high-energy astronomy.

They achieved an accurate measurement in the ultra-high energy band from 0.3 to 1.1 PeV (1 PeV is equivalent to one quadrillion electronvolts) for the first time, thus calibrating the brightness of the standard candle over an unprecedented energy range.

Scientists have also detected a photon with an energy of 1.1 PeV, indicating the presence of an extremely powerful electron accelerator about one-tenth the size of the solar system in the core region of the Crab Nebula.

The accelerator can energize electrons to a level 20,000 times greater than the largest human-made electron accelerator on Earth could ever achieve, thus approaching the absolute theoretical limit posed by classical electrodynamics and ideal magnetohydrodynamics, said Cao Zhen, chief scientist of LHAASO.

"In 1054, the imperial astronomers of China's Northern Song Dynasty witnessed a supernova explosion. About 967 years on, a new observation of the supernova remnant by LHAASO has amazed us again," said Cao.

LHAASO, covering an area of 1.36 square km and still under construction at 4,410 meters above sea level in Daocheng County, southwest China's Sichuan Province, is expected to be completed by the end of July and subsequently put into full operation.

Scientists expect to detect one to two photons with energies of approximately 1 PeV in the Crab Nebula every year, so the puzzle of the cosmic PeV electron accelerator will be unraveled in the coming years, Cao added.

The study, led by the Institute of High Energy Physics under the Chinese Academy of Sciences, was published in the latest edition of Science.

Arctic Bay elder Qapik Attagutsiak, who turned 101 on June 11, is one of 12 Indigenous Canadians nominated for an Indspire lifetime achievement award this year. “Qapik’s lifework has embodied both Inuit Qaujimajatuqangit and Inuit societal values. Her longevity and her legacy represent a shining example for young Inuit to follow,” says the backgrounder on her nomination. The Indspire award ceremony will be broadcast on APTN and CBC on June 22. (File photo courtesy of Parks Canada)

Northrop to build homes on moon orbit under $935 mln NASA contract

Updated At: Jul 11, 2021

Northrop Grumman Corp (NOC.N) won a NASA contract worth $935 million to develop living quarters for the US space agency's planned outpost in lunar orbit, the weapons maker said on Friday.

Astronauts will live and conduct research in the Habitation And Logistics Outpost (HALO) made by Northrop for the lunar Gateway — a vital component of NASA's Artemis moon programme.

China is also planning to set up a base in the south pole of the moon, and is deploying robotic expeditions to asteroids and Jupiter around 2030. read more

NASA and its commercial and international partners are building Gateway to support science investigations and enable surface landings at the moon, the agency said in a statement.

Northrop Grumman will be responsible for attaching and testing the integrated quarters with a solar propulsion module being developed.

Eight countries have signed an international pact for moon exploration as a part of NASA's Artemis program as the U.S. space agency tries to shape standards for building long-term settlements on the lunar surface.

NASA is targeting a November 2024 launch for the integrated spacecraft on a SpaceX rocket. Reuters

BOLSHEVIKS ON MARS

Russian Space Agency proposes putting nuclear power station on Mars

Sputnik July 11, 2021

Engineers say the power plant can be delivered to the Red Planet using the Zeus – a prospective Russian nuclear-powered space tug design expected to begin flight-testing in 2030.

Specialists from the Arsenal Design Bureau – a St. Petersburg-based subsidiary of Russia’s Roscosmos space agency specialising in the production of spacecraft, satellites, and other space technologies – have proposed the creation of a nuclear power plant for a future Russian Mars base.

Sputnik was able to familiarise itself with the proposal – which recommends using technologies developed for the Zeus interplanetary space tug for a stationary nuclear reactor for the Martian surface as well.

Under Arsenal’s proposal, the reactor would be delivered to Red Planet aboard the Zeus, and floated down to its surface using a parachute system. After landing, the power plant would be activated to provide energy to a prospective Russian martian base.

On top of that, engineers say that if the Zeus were to be deployed at the Lagrange point between the Sun and Mars (i.e. the point in space where gravitational forces of these bodies are equally strong), its onboard communications sensors and transmitters could serve as a “high-speed channel for the transmission of information to Earth from the surface of Mars and from spacecraft orbiting the planet.”

Earlier, Sputnik reported that the Zeus project’s proposed megawatt-class electric propulsion system would allow it to disable the control systems of adversarial spacecraft using an electromagnetic impulse, and even allow it to fire laser beams.

Designers at the Moscow-based Keldysh Research Centre have also suggested the spacecraft class can be used as a component in Russia’s air defence network – detecting targets from orbit and relaying this information to ground-based missile systems.

Russia has been working on the creation of an interplanetary spacecraft with a nuclear power plant since 2010. In 2019, a concept for the space tug was presented for the first time at the MAKS International Aviation and Space Show outside Moscow, with a more detailed presentation given at the ARMY-2020 forum.

Last December, Roscosmos signed a $56.5 million contract with the Arsenal Design Bureau for experimental design work for the Zeus. This work is expected to be completed by 2024, with flight testing hopefully starting in 2030.

In June, Roscosmos Chief Dmitry Rogozin said that in addition to Mars, Zeus tugs could be sent to other planets, including Venus, and even travel beyond our solar system, where they can search for alien life.

Roscosmos has announced a series of ambitious plans in recent years, including the construction of the first Russian-only space station since the deorbiting of Mir in 2001, and plans for a series of manned and unmanned missions to the Moon and even a possible Moon base. Russia’s space programme has faced two major problems, however: a lack of sufficient funding to realise some of its ambitious projects, and the concentration of funds and other resources for arguably questionable purposes – such as the ongoing construction of a 250,000 square metre office centre next to the legendary Khrunichev space rocket factory in Moscow.

Despite a long list of space firsts (including first satellite, first man and woman in space, first space station, first Moon and Mars landing, etc.) Russia spent just $3.58 billion on its space programme in 2020, just $260 million more than Japan, and less than France ($4.04 billion), China ($8.85 billion) and the United States ($47.69 billion). These and other factors have left the country which once enjoyed the status of a space pioneer looking on as China’s space agency and NASA show off the latest images and footage of their rovers roaming around on the Martian surface.

Red Star (novel) - Wikipedia

https://en.wikipedia.org/wiki/Red_Star_(novel)

Red Star (Russian: Красная звезда) is Alexander Bogdanov's 1908 science fiction novel about a communist society on Mars. The first edition was published in St. Petersburg in 1908, before eventually being republished in Moscow and Petrograd in 1918, and then again in Moscow in 1922. Set in early Russia during the Revolution of 1905 and additionally on a fictional socialist society on Mars, t…

Could Methane-Spewing Microbes Be Living in the Depths of a Subsurface Ocean on Saturn’s Moon Enceladus?

The hot, chemical plumes could be produced by something similar to Earthly microscopic life forms that consume hydrogen and carbon, then burp up methane

The plumes were first discovered in 2006 when the Cassini spacecraft spotted the geysers shooting water and other organic materials at high velocities hundreds of miles into space near the moon's south pole. (NASA/JPL/Space Science Institute under public domain)

By Elizabeth Gamillo

SMITHSONIANMAG.COM
JULY 8, 2021

When NASA's Cassini spacecraft circled Saturn and its icy moons from 2004 to 2017, scientists learned one moon may not be a frozen, lifeless celestial object after all. Enceladus, Saturn’s sixth largest moon, is an active moon with an ocean laying underneath its crust and hydrothermal vents deep beneath its icy shell that spew water ice, hydrogen and methane—all the ingredients microscopic life forms love here on Earth.

Now, new research shows those plumes shooting from the Enceladus' surface contain high amounts of methane and may be a sign that the moon can potentially harbor life, according to a study published last month in Nature Astronomy. Researchers speculate the methane could be produced by something similar to Earthly methanogenic microbes that consume hydrogen and carbon and burp up methane near deep-sea vents on the ocean floor, reports Charlie Wood for Popular Science.

The plumes were first discovered in 2006 when the Cassini spacecraft spotted the geysers shooting water ice and other organic materials at high velocities hundreds of miles into space near the moon's south pole, reports Passant Rabie for Inverse. The geysers are thought to feed Saturn's E ring, the planet's second outermost ring.

Ten years later, when Cassini cruised around Enceladus, the spacecraft dove directly into the plumes vapor 30 miles from the moon's surface, reports Paul Scott Anderson for EarthSky. During the dive, Cassini took samples of the spray and used mass-spectroscopy to reveal that the plumes contained high concentrations of methane, carbon monoxide, carbon dioxide, hydrogen, and various other materials, Inverse reports. The hydrogen may be produced by the deep-sea hydrothermal vents on the moon's seafloor, in a similar way that may have started life on Earth as well, reports Mike Wall Space.com.

On Earth, microorganisms that live within deep-sea vents use hydrogen and carbon dioxide to produce methane in a method called methanogenesis, reports Popular Science. Researchers suspect Saturn's moon may have microbes producing the plumes because of the amount of methane Cassini detected. However, methane can be made without the help of microbes.

Methane can be produced non-biologically through a chemical reaction called serpentinization when hot water interacts with minerals in rocks and creates hydrogen. But the amount of methane detected by the Cassini spacecraft was too much to be made by serpentinization alone, reports EarthSky.

To see how Enceladus may produce the abundance of methane and hydrogen, scientists at the University of Arizona and Paris Sciences & Lettres University used mathematical models that combined plausible serpentinization rates that Enceladus may use to make hydrogen and methane on its own. They also used another model that looked at how the rates would change if the moon had microbes creating methane through methanogens, Popular Science reports

The researchers found that the amount of methane detected is too high to be produced on its own without something else also releasing methane. However, the amount of methane detected by Cassini may match the amount produced if it were occurring on Enceladus through both serpentinization and microbes, the researchers explain in a statement.

"Obviously, we are not concluding that life exists in Enceladus' ocean," says study author Régis Ferrière, an astrobiologist at the University of Arizona, in a statement. "Rather, we wanted to understand how likely it would be that Enceladus' hydrothermal vents could be habitable to Earthlike microorganisms. Very likely, the Cassini data tell us, according to our models. And biological methanogenesis appears to be compatible with the data. In other words, we can't discard the 'life hypothesis' as highly improbable. To reject the life hypothesis, we need more data from future missions."

The abundance of methane could also be rising from the moon's core, if it formed from colliding comets or other unknown reasons yet to be discovered, per Popular Science.

More missions and research are needed to determine whether methane is genuinely being produced by microbes or some other process entirely. Researchers are hoping for another mission focused on astrobiology that would probe and measure the chemical compounds on Enceladus and its ocean.

"The ultimate dream for people like me would be to drill through the cracks on Enceladus, and having some kind of submarine hovering around in Enceladus' ocean and taking all kinds of cool measurements," says Marc Rovira-Navarro, a planetary scientist not involved with the study, to Inverse.

First Marsquake Launches Field of Martian Seismology

BROOKS MCKINNEY
Jul 10th 2021

On April 6, 2019, the Seismic Experiment for Interior Structure (SEIS) instrument on NASA’s Mars Insight Lander recorded a phenomenon never observed, even since the agency’s Viking spacecraft began exploring the Red Planet 45 years ago: a trembling of the ground emanating, it appeared, from deep inside Mars.

Since then, more than 480 such seismic events have been recorded. That first “marsquake” was estimated to have a magnitude between 1 to 2, a level barely detectable on seismometers on Earth. In the words of Bruce Banerdt, Insight Principal Investigator of NASA’s Jet Propulsion Laboratory, Pasadena, California, it marked “the beginning of a new field: martian seismology.”
Hitting the Ground Listening

Developed by the French space agency Centre National d’Études Spatiales, Insight’s SEIS instrument is designed to sense vibrations caused by marsquakes and Martian weather systems such as dust storms. It’s also the first seismometer to be deployed directly on the Martian surface.

The earlier Viking 1 and 2 seismometers were mounted on top of their lander’s equipment bay, which made them vulnerable to noise caused by the wind, reducing their sensitivity by three orders of magnitude. SEIS’s innovative technology includes several insulating barriers, including a dome-shaped wind and thermal shield, to protect it from Mars’ extreme temperatures and high winds.

Insight’s Marsquake Service Team, which is led by the Swiss Federal Institute of Technology (ETH Zürich), reviews and analyzes SEIS data about twice per day to learn more about Mars’ geology.

According to an ETH Zürich news report, the Martian surface is very quiet seismically. But during the day, strong winds shake the Lander and its instrumentation, which creates vibration and a high level of ambient noise. This noise effectively drowns out faint seismic signals from marsquakes. Then, during evening hours after the winds have died down, the innovative technology of the SEIS instrument — ETH Zürich calls it “arguably the most sensitive seismometer ever operated” — allows it to detect and record Mars’ faintest seismic signals.
Unraveling the Waves

On Earth, quakes occur on fault lines created by the movement of adjacent tectonic plates. The Red Planet, however, does not have tectonic plates. Scientists believe that marsquakes are caused primarily by the cooling and contraction of Mars, which creates stress, as ETH Zürich reports. Over time, this stress builds up until it’s strong enough to break the crust, resulting in marsquakes.

The SEIS scientists point out that marsquakes, like earthquakes, generate two types of seismic waves: fast-moving P- (primary) waves and slower-moving S- (secondary) waves. When P-waves travel through a planet and encounter a discontinuity in materials (think interface between a solid mantle and a liquid core), they can be reflected back to their source, change direction or even change into a slower-moving S-wave.

By analyzing the arrival times of different types of seismic waves at the Insight lander’s location, seismologists can gain valuable insight into Mars’ geology, including the location, depth, thickness and composition of its internal layers.
Following the Science

To date, as Nature magazine reports, the SEIS instrument has measured two types of marsquakes. The most common type shakes the ground at high frequencies and is linked to fractures of the shallow Martian crust. The less common type is characterized by low-frequency vibrations and appears to emanate from sources within Mars’ mantle.

The February 2020 analysis by seismologists at ETH Zürich revealed that of 174 registered marsquakes, 24 could be considered low-frequency events with magnitudes between 3 and 4, with seismic waves propagating through the Martian mantle. The two largest of these appeared to emanate from the tectonically active zone of Mars known as Cerburus Fossae. The other 150 quakes had even smaller magnitudes and high-frequency waves trapped in the Martian crust.

As Nature magazine highlights, the analysis of these seismic waves have led the ETH Zürich seismologists to conclude that the upper 8 to 11 kilometers of the Martian crust beneath the Insight lander is fractured or highly altered. They are still investigating composition of the mantle.

The ETH Zürich team has also observed that marsquakes are much different from earthquakes in their duration. Instead of the 10 to 30 seconds typical for earthquakes, marsquakes appear to last for 10 to 20 minutes. The scientists are still investigating the reasons behind this dramatic difference.
Adding Momentum

To date, according to NASA, the Insight mission has “produced exceptional science.” As a result, the agency has extended the Lander’s mission for another two years, through December 2022. This extension will give the Lander’s instruments more time to monitor and measure marsquakes and weather phenomena on the Martian surface.

According to NASA, between now and the summer of 2021, the Insight science team will be operating the Lander’s key instruments in a power conservation mode. This strategy reflects the onset of the Martian winter, when the already faint sunlight on the Red Planet’s surface will become even fainter and the dust accumulation on Insight’s solar panels — which has reduced their output power to just 27% of their “dust-free” capacity — will increase. NASA mission planners had hoped that small dust storms near the Lander would periodically clean off its solar panels, but to date, that has not happened. The Insight team plans to resume full science operations in July when Mars begins approaching the Sun again.

Weather and astronomical issues notwithstanding, NASA scientists are looking forward to continuing Insight’s very productive science mission on Mars, making new discoveries and even adding momentum to human dreams to one day explore and colonize the Red Planet.

Interested in all things in outer space and exploration? We are, too. Take a look at open positions at Northrop Grumman and consider joining our team.

New Type of Stellar Grain Discovered

July 09, 2021

Unusual chemistry of grain could tell scientists more about the origin of Earth's water

Scientists have discovered a new type of star dust whose composition indicates that it formed during a rare form of nucleosynthesis (the process through which new atomic nuclei are created) and could shed new light on the history of water on Earth.

A team led by cosmochemists from Caltech and Victoria University of Wellington in New Zealand studied ancient minerals aggregates within the Allende meteorite (which fell to Earth in 1969) and found that many of them had unusually high amounts of strontium-84, a relatively rare light isotope of the element strontium that is so-named for the 84 neutrons in its nucleus.

"Strontium-84 is part of a family of isotopes produced by a nucleosynthetic process, named the p-process, which remains mysterious," says Caltech's François L. H. Tissot, assistant professor of geochemistry. "Our results points to the survival of grains possibly containing pure strontium-84. This is exciting, as the physical identification of such grains would provide a unique chance to learn more about the p-process."

Tissot and collaborator Bruce L. A. Charlier of Victoria University of Wellington are co-lead authors on a study describing the findings that was published in Science Advances on July 9.

"This is really interesting," Charlier says. "We want to know what the nature of this material is and how it fits into the mix of ingredients that went to form the recipe for the planets."

Strontium (atomic symbol: Sr), a chemically reactive metal, has four stable isotopes: strontium-84 and its heavier cousins that have 86, 87, or 88 neutrons in their nuclei. Scientists have found that strontium is useful when attempting to date objects from the early solar system because one of its heavy isotopes, strontium-87, is produced by the decay of the radioactive isotope rubidium-87 (atomic symbol: Rb).

Rubidium-87 has a very long half-life, 49 billion years, which is more than three times the age of the universe. Half-life represents the amount of time required for the radioactivity of an isotope to drop to one-half its original value, allowing these isotopes to serve as chronometers for dating samples on varying time scales. The most famous radioactive isotope used for dating is carbon-14, the radioactive isotope of carbon; with its half-life of roughly 5,700 years, carbon-14 can be used to determine the ages of organic (carbon-containing) materials on human timescales, up to about 60,000 years. Rubidium-87, in contrast, can be used to date the oldest objects in the universe, and, closer to home, the objects in the solar system.

What is particularly attractive about using the Rb–Sr pair for dating is that rubidium is a volatile element—that is, it tends to evaporate to form a gas phase at even relatively low temperatures—while strontium is not volatile. As such, rubidium is present at a higher proportion in solar system objects that are rich in other volatiles (such as water), because they formed at lower temperatures.

A CAI inclusion in the Allende meteorite. This inclusion contains strontium, which was isolated and studied by Tissot and colleagues.

Counterintuitively, Earth has an Rb/Sr ratio that is 10 times lower than that of water-rich meteorites, implying that the planet either accreted from water-poor (and thus rubidium-poor) materials or it accreted from water-rich materials but lost most of its water over time as well as its rubidium. Understanding which of these scenarios took place is important for understanding the origin of water on Earth.

In theory, the Rb–Sr chronometer should be able to tease apart these two scenarios, as the amount of Sr-87 produced by radioactive decay in a given amount of time will not be the same if Earth started with a lot of rubidium versus less of the material.

In the latter scenario, i.e., with less rubidium, the newly formed Earth would have been poor in volatiles such as water, thus the amount of Sr-87 in the earth and in volatile-poor meteorites would be similar to that observed in the oldest-known solar system solids, the so-called CAIs. CAIs are calcium- and aluminum-rich inclusions found in certain meteorites. Dating back 4.567 billion years, CAIs represent the first objects that condensed in the early solar nebula, the flattened, rotating disk of gas and dust from which the solar system was born. As such, CAls offer a geologic window into how and from what type of stellar materials the solar system formed.

"They are critical witnesses to the processes that were happening while the solar system was forming," says Tissot.

However, the composition of CAIs has long muddled scientists' ability to determine if Earth formed mostly dry or not. That is because CAls, unlike other solar-system materials, have anomalous ratios of the four strontium isotopes, with a slightly elevated proportion of strontium-84. Thus, they pose a challenge to the validity of the rubidium–strontium dating system. And they also raise a key question: Why are they different?

To learn more, Tissot and Charlier took nine specimens of so-called fine-grained CAls. Fine-grained CAIs have preserved their condensate (that is, snowflake-like) texture, which testifies to their pristine nature.

The team painstakingly leached out these CAIs by bathing them in gradually harsher acids to strip away the more chemically reactive minerals (and the strontium they contain), leaving a concentrate of only the most resistant fraction. The final sample contained almost pure Sr-84, while a typical sample is composed of 0.56 percent Sr-84.

"Step-leaching is a little bit of a blunt instrument because you are not entirely sure what exactly it is you are destroying at each step," Charlier says. "But the nub of what we've found is, once you have stripped away 99 percent of the common components within the CAIs, what we are left with is something highly exotic that we weren't expecting."

"The signature is unlike anything else found in the solar system," Tissot says. The grains carrying this signature, Tissot and Charlier concluded, must have formed prior to the birth of the solar system and survived that cataclysmic process during which stellar grains were heated to extremely high temperatures, vaporized, and then condensed into solid materials.

Given the relative abundance of strontium-84, the discovery points to the likely existence in meteorites of nanometer-sized grains containing almost pure strontium-84 that were formed during a rare nucleosynthetic process before the formation of the solar system itself. The nature of these grains is still a mystery, as only their isotopic composition in strontium reveals their existence. But the high levels of Sr-84 in the CAIs suggest that Earth and volatile-poor meteorites have more strontium-87 than CAIs, favoring the scenario in which Earth accreted with more water and volatile elements, which were subsequently lost within the first few million years after their formation.

The Science Advances paper is titled "Survival of presolar p-nuclide carriers in the nebula revealed by stepwise leaching of Allende refractory inclusions." Co-authors include Caltech graduate student Ren T. Marquez, Hauke Vollstaedt of Thermo Fisher Scientific in Bremen, Germany, Nicolas Dauphas of the University of Chicago, and Colin J. N. Wilson of Victoria University of Wellington. Funding to support this research came from Victoria University of Wellington, Caltech, NASA, the National Science Foundation, and MIT.

Top image: A side view of the Allende meteorite, displaying the white CAl inclusions.

Indian researchers spot rare super-luminous supernova shining with borrowed energy source

A deep study of such ancient spatial objects can help probe the mysteries of the early universe, the Department of Science and Technology says

Updated At: Jul 10, 2021

Photo for representation only

New Delhi, July 10

An extremely bright, hydrogen-deficient, fast-evolving supernova that shines with the energy borrowed from an exotic type of neutron star with an ultra-powerful magnetic field has been spotted by Indian researchers.

A deep study of such ancient spatial objects can help probe the mysteries of the early universe, the Department of Science and Technology (DST) said.

Supernovae (SNe) are highly energetic explosions in the universe releasing an enormous amount of energy. Such types of supernovae called SuperLuminous Supernova (SLSNe) are very rare.

This is because they generally originated from very massive stars (minimum mass limit is more than 25 times that of the sun), and the number distribution of such massive stars in our galaxy or in nearby galaxies is sparse. Among them, SLSNe-I has been counted to about 150 entities spectroscopically confirmed so far, the DST said.

These ancient objects are among the least understood SNe because their underlying sources are unclear, and their extremely high peak luminosity is unexplained, it said.

The SN 2020ank, first discovered by the Zwicky Transient Facility on January 19, 2020, was studied by scientists from Aryabhatta Research Institute of Observational Sciences (ARIES) Nainital, a research institute under the Department of Science and Technology (DST), from February 2020 and then through the coronavirus lockdown phase of March and April, the DST said.

The apparent look of the SN was very similar to other objects in the field. However, once the brightness was estimated, it turned out as a very blue object reflecting its brighter character, it said.

The team observed it using special arrangements at India's recently commissioned Devasthal Optical Telescope (DOT-3.6m) along with two other Indian telescopes: Sampurnanand Telescope-1.04m and Himalayan Chandra Telescope-2.0m, it said.

They found that the outer layers of the onion structured supernovae had been peeled off, and the core was shining with a borrowed energy source, it added.

The study led by Amit Kumar, a PhD student working under SB Pandey, and published in the Monthly Notice of the Royal Astronomical Society, suggested a possibly powering source from an exotic type of neutron star with an ultra-powerful magnetic field (magnetar), the DST said.

Deeper investigations could explore the underlying physical mechanisms, possible progenitors, and environments hosting such rare explosions and their possible associations with other energetic explosions like Gamma-ray bursts (GRBs) and Fast Radio Bursts (FRBs), the DST said. PTI

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