From Science Alert: “NASA Reveals Wild Project For Turning a Moon Crater Into a Radio Telescope”

From Science Alert

(Saptarshi Bandyopadhyay)

9 APRIL 2020
DAVID NIELD

NASA just gave out a new round of grants for its favourite up and coming innovative space projects – one of which is a plan to fit a 1 kilometre (3,281 foot) radio telescope inside a crater on the far side of the Moon.

The Lunar Crater Radio Telescope (LCRT) would be able to measure wavelengths and frequencies that can’t be detected from Earth, working unobstructed by the ionosphere or the various other bits of radio noise surrounding our planet.

Should the plans for the LCRT become a reality – and the new grant money could get it closer to that – it would be the largest filled-aperture radio telescope in the Solar System.

How the LCRT might look. (Saptarshi Bandyopadhyay)

“LCRT could enable tremendous scientific discoveries in the field of cosmology by observing the early universe in the 10–50m wavelength band (6–30MHz frequency band), which has not been explored by humans to date,” writes robotics technologist Saptarshi Bandyopadhyay of the NASA Jet Propulsion Laboratory (JPL) in his project outline.

As per the plans, Moon rovers would pull out a wire mesh some 1 kilometre across, inside a lunar crater than could be up to 5 kilometres (3.1 miles) in diameter. A suspended receiver in the centre of the crater would complete the system.

Everything could be automated without any human operators, which would in turn mean a lighter and less expensive payload for the project to literally get off the ground.

This is still at the very early stage of planning, and it’s not clear yet exactly which crater would be used for the job, but it’s an intriguing concept that we’ll be keeping an eye on in the years ahead.

The biggest radio telescope here on Earth is the Five-hundred metre Aperture Spherical Telescope or FAST, which has a 500 metre (1,640 foot) diameter.

FAST [Five-hundred-meter Aperture Spherical Telescope] radio telescope, with phased arrays from CSIRO engineers Australia [located in the Dawodang depression in Pingtang County, Guizhou Province, south China

Should the LCRT eventually get put together, it would be twice as wide.

The LCRT would be installed by rovers. (Saptarshi Bandyopadhyay)

FAST is already proving its worth, having already picked up mysterious fast radio bursts or FRBs from the depths of space. The LCRT proposed here has the potential to pick up many more phenomena.

There’s now such an abundance of low Earth orbit satellites, listening to the cosmos from the surface of our planet is becoming increasingly difficult.

Working at low frequencies in the 6 to 30MHz frequency band, the lunar crater telescope could perhaps tell us more about the earliest days of the Universe.

China and the Netherlands have already set up a radio telescope on the far side of the Moon, albeit a much smaller one. This telescope uses satellites to relay data back to Earth, like the LCRT will have to, if we pull it off.

The team behind the concept now has nine months and up to US$125,000 of NASA money to see if they can develop it further. Let’s hope they’re successful.

“Building the largest filled-aperture radio telescope in the Solar System on the far-side of the Moon is bound to create a lot of public excitement,” Bandyopadhyay and his colleagues write in a 2018 paper on the idea.

“We envisage that this concept would unlock the potential for ground-breaking scientific discoveries in radio astronomy in wavelengths that are hitherto poorly explored by humans so far.”

See the full article here .

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From Science Alert: “This Epic Ion Engine Will Power NASA’s Test Mission to Redirect an Asteroid”

From Science Alert

29 MARCH 2020
EVAN GOUGH

(NASA/Bridget Caswell)

Despite humanity’s current struggle against the novel coronavirus, and despite it taking up most of our attention, other threats still exist. The very real threat of a possible asteroid strike on Earth in the future is taking a backseat for now, but it’s still there.

Though an asteroid strike seems kind of ephemeral right now, it’s a real threat, and one that has the potential to end humanity. Agencies like NASA and the ESA are still working on their plans to protect us from that threat.

NASA’s DART (Double Asteroid Redirection Test) mission is scheduled to launch on 22 July 2021.

NASA DART Double Impact Redirection Test vehicle depiction schematic

It’s a demonstration mission to study the use of kinetic impact to deflect an asteroid. It’ll head for the tiny binary asteroid system called Didymos, (or 65803 Didymos.) This double asteroid system poses no threat to Earth.

The larger of the pair, named Didymos A, is about 780 meters (2560 ft.) in diameter, while the smaller one, Didymos B, is only about 160 meters (535 feet) DART will crash itself into the Didymos B. It’s close to the typical size of an asteroid that threatens Earth.

A simulated image of the Didymos binary asteroid. (Naidu et al., AIDA Workshop, 2016)

DART has a lot of space to cover to reach Didymos. After launching in July 2021, it will reach its target in September 22, when the binary asteroid is within 11 million km (6.8 million miles) of Earth. And to get there, it’ll rely on a powerful ion engine called NASA’s Evolutionary Xenon Thruster – Commercial (NEXT-C).

The engine comes in two primary components: the thruster and the power processing unit (PPU.) NEXT-C is getting ready for the mission with a series of tests, both performance and environmental.

The thruster was put through vibration, thermal vacuum and performance tests before being integrated with its PPU. It was also subjected to simulated spaceflight conditions: the extreme vibration during launch, and the extreme cold of space.

The power processing unit of the thruster is removed from another vacuum chamber after successful testing. (NASA/Bridget Caswell)

NEXT-C is a powerful engine. It’s nothing like a rocket, which requires a massive amount of thrust to lift something away from Earth’s gravity. But in terms of ion drives, it’s a very powerful unit. It’s about three times more powerful than the NSTAR ion drives on NASA’s DAWN and Deep Space One spacecraft.

NASA/DLR Dawn Spacecraft (2007-2018)

Deep Space One spacecraft. Wikipedia

NEXT can produce 6.9 kW thrust power and 236 mN thrust. The engine has produced the highest total impulse of any ion engine: 17 MN·s. It also has a specific impulse, which is a measure of how efficiently it uses propellant, of 4,190 seconds, compared to NSTAR’s 3,120.

Ion drives don’t burn fuel like a rocket, though they do use a propellant. Typically the propellant is xenon, like in NEXT-C. The NEXT-C ion engine is a double-grid system.

The xenon is fed into a chamber, where it encounters the first, or upstream, grid. Solar arrays provide the electricity, and the first grid is charged positive. As the xenon ions pass through the upstream grid, they are charged positively.

This draws them toward the second or accelerator grid, which is charged negatively. This propels them out of the engine, providing thrust. The thrust is equal to the force between the upstream ions and the accelerator grid.

NASA Evolutionary Xenon Thruster being tested in a vacuum chamber. (NASA)

When DART reaches the Didymos binary asteroid, it will have some company. The Italian Space Agency is providing LICIA (Light Italian CubeSat for Imaging of Asteroids) for the mission.

https://www.nanosats.eu/sat/liciacube

LICIA is 6 cubesats that will separate from DART prior to impact with Didymos B. It’ll capture images of the impact and the debris ejected from the collision and transmit it back to Earth.

The impact is expected to change Didymos B’s orbital velocity by about a half millimeter per second. That will change its rotation period by a large enough amount that Earth-based telescopes will detect it. It will also leave a crater in the surface, about 20 m (66 ft) wide.

Though DART will be destroyed when it impacts, the ESA is planning a follow-up mission. It’s called Hera, and it’s scheduled to launch in 2024, and to arrive in 2027.

ESA’s proposed Hera spaceraft depiction

Hera will investigate not only the effect of DART’s impact, but will carry a suite of instruments to learn more about binary asteroids, and the interior of the asteroid.

See the full article here .

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From Science Alert: “Necroplanetology: The Strangest Field of Astronomy You’ve Never Heard Of”

From Science Alert

28 MARCH 2020
MICHELLE STARR

(NASA/JPL-Caltech)

In 2015, astronomers found something weird. It was a white dwarf star, 570 light-years from Earth, with a peculiar dimming pattern. It dimmed several times to varying depths, each depth repeating on a 4.5 to 5-hour timeframe; and its atmosphere was polluted with elements usually found in rocky exoplanets.

It didn’t take long before they figured it out. The gravity of the dead star was in the process of shredding and devouring bodies in orbit around it, a violent process known rather politely as tidal disruption.

The star is called WD 1145+017, and it’s now being used as a proof of concept for a new field of planet study, forensic reconstruction of planetary bodies to understand what they were like, and how they died.

Astronomers from the US and the UK are calling this field necroplanetology.

Their analysis of WD 1145+017 has been accepted into The Astrophysical Journal, and is available on arXiv [https://arxiv.org/abs/2003.08410]. And it could, the researchers say, be applied to future discoveries similar to the white dwarf system to piece together how planets die orbiting different kinds of dead stars.

Although white dwarfs eject a lot of material when they die in a series of violent thermonuclear explosions, planets can somehow survive the process. Not only have we found planets in orbit around white dwarf stars, we have found elements in the atmospheres of white dwarf stars that are usually found inside rocky exoplanets.

The surface gravity of white dwarfs is so intense that these heavier elements would sink quite quickly, indicating that the star must have accreted the material quite recently, from a body that survived the star’s death throes.

To try and determine how WD 1145+017 got the way it did, astronomers from the University of Colorado, Boulder, Wesleyan University, and the University of Warwick in the UK conducted a series of simulations to place constraints on the tidally disrupted body.

They tweaked structural components of an orbiting body, such as the size of the core and mantle; the composition of the mantle, rocky or icy; and the presence of a crust. This resulted in 36 different simulated bodies.

Then, they set each of these 36 bodies orbiting a star like WD 1145+017, around 60 percent of the mass of the Sun, and 2 percent of its size (white dwarfs are pretty dense).

This orbit was 4.5 hours, as per the material orbiting WD 1145+017, and each simulation ran for 100 orbits. And finally, the resulting light curves for the tidal disruption of each body were then compared with the real-life light curve of WD 1145+017.

These simulations showed that the bodies most likely to produce what we observe in WD 1145+017 have a small core, and a low-density mantle, “resembling an asteroid with a partially differentiated structure and volatile-rich mantle like Vesta,” the researchers wrote in their paper.

The bodies are relatively low mass, and have bulk density high enough to maintain structure for a while, but low enough that their mantles are disrupted. These attributes are consistent with the lack of small particles found in other observations of the star, since these would sublimate quickly.

And, in fact, they offer some clues as to other mysterious stars as well – such as the famous KIC 8462852, AKA Tabby’s star, whose inconsistent dimming is a source of much puzzlement among astronomers.

KIC 8462852, since its strange behaviour was first discovered, has turned out not to be the only star exhibiting such strange dimming. A survey last year turned up another 21 strangely dimming stars that could have similar dynamics.

And other white dwarfs slurping down orbiting bodies have been discovered, too. ZTF J0139+5245 and WD J0914+1914 were both discovered tidally disrupting planets last year.

These stars could be simulated using the team’s new methods, too.

“These are the first members of a larger class of dying planetary systems that must be studied by pairing spectroscopic and photometric observations with disruption simulations, either tidal as in WD 1145+017 or rotational as Veras et al. (2020) proposes for the body transiting ZTF J0139+5245,” the researchers wrote in their paper.

“This multi-pronged approach would use the death of these planetary systems in action to study fundamental properties of exoplanetary bodies that are otherwise inaccessible: a study in necroplanetology.”

See the full article here .

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From Science Alert: “Just Three Orbiting Black Holes Can Break Time-Reversal Symmetry, Physicists Find”

From Science Alert

25 MARCH 2020
MICHELLE STARR

(wragg/Getty Images)

Most of the laws of physics don’t care which direction time is travelling. Forwards, backwards… either way, the laws work exactly the same. Newtonian physics, general relativity – time is irrelevant to the mathematics: This is called time-reversal symmetry.

In the real Universe, things get a bit messier. And now a team of scientists led by astronomer Tjarda Boekholt of the University of Aveiro in Portugal have shown that it takes as few as three gravitationally interacting bodies to break time-reversal symmetry.

“Hitherto, a quantitative relation between chaos in stellar dynamical systems and the level of irreversibility remained undetermined,” they wrote in their paper.

“In this work we study chaotic three-body systems in free fall initially using the accurate and precise n-body code Brutus, which goes beyond standard double-precision arithmetic. We demonstrate that the fraction of irreversible solutions decreases as a power law with numerical accuracy.”

The n-body problem is a famous problem in astrophysics. It arises as you add more bodies to a gravitationally interacting system.

The movements of two bodies of comparable size in orbit around a central point are relatively simple to mathematically predict, according to Newton’s laws of motion and Newton’s law of universal gravitation.

However, once you add another body, things become tricky. The bodies start to gravitationally perturb each others’ orbits, introducing an element of chaos into the interaction. This means that, although solutions exist for special cases, there is no one formula – under Newtonian physics or general relativity – that describes these interactions with complete accuracy.

Even within the Solar System, which we understand pretty well, we can only predict a few million years into the future. Chaos in the Universe is a feature, not a bug.

When running n-body simulations, physicists sometimes return time-irreversibility in their results – in other words, running the simulations backwards doesn’t get them to the original starting point.

What has been unclear is whether this is a result of the chaos of these systems, or problems with the simulations, leading to uncertainty over their reliability.

So, Boekholt and his colleagues designed a test to figure this out. He and computational astrophysicist Simon Portegies Zwart of Leiden University in the Netherlands previously wrote an n-body simulation code called Brutus that uses brute-force computing power to reduce the magnitude of numerical errors.

Now, they have used it to test the time-reversibility of a three-body system.

“Since Newton’s equations of motion are time reversible, a forward integration followed by a backward integration of the same time should recover the initial realisation of the system (albeit with a sign difference in the velocities),” they wrote in their paper.

“The outcome of a reversibility test is thus exactly known.”

The three bodies in the system are black holes, and they were tested in two scenarios. In the first, the black holes started from rest, moving towards each other into complicated orbits, before one of the black holes is kicked out of the system.

The second scenario starts where the first one ends, and is run backwards in time, trying to restore the system to its initial state.

They found that, 5 percent of the time, the simulation could not be reversed. All it took was a disturbance to the system the size of a Planck length, which, at 0.000000000000000000000000000000000016 metres, is the smallest length possible.

“The movement of the three black holes can be so enormously chaotic that something as small as the Planck length will influence the movements,” Boekholt said. “The disturbances the size of the Planck length have an exponential effect and break the time symmetry.”

Five percent may not seem like much, but since you can never predict which of your simulations will fall within that five percent, the researchers have concluded that n-body systems are therefore “fundamentally unpredictable”.

And they have shown that the problem is not with the simulations after all.

“Not being able to turn back time is no longer just a statistical argument,” Portegies Zwart said. “It is already hidden in the basic laws of nature. Not a single system of three moving objects, big or small, planets or black holes, can escape the direction of time.”

The research has been published in the Monthly Notices of the Royal Astronomical Society.

See the full article here .

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From Science Alert: “It Looks Like That Interstellar Comet Came All The Way to The Solar System to Die”

From Science Alert

23 MARCH 2020
MICHELLE STARR

(NASA/ESA/David Jewitt/Paul Kalas)

A comet that entered our Solar System from interstellar space may not make it out again. As it zooms away from the Sun, 2I/Borisov has been spotted spewing out material in two cometary outbursts.

These outbursts show that the comet is disintegrating, according to Polish astronomers from the Jagiellonian University in Krakow and the University of Warsaw who recorded the activity.

“This behaviour is strongly indicative of an ongoing nucleus fragmentation,” they wrote in a notice posted to Astronomers Telegram.

2I/Borisov first drew the world’s attention at the end of August last year, when it was officially discovered whizzing through the Solar System on a trajectory that indicated an interstellar origin.

Scientists later pored through observation data, and found images of the comet dating all the way back to December 2018. This wealth of additional data supported conclusions about the comet’s interstellar origins, and allowed for a more precise prediction of its future trajectory.

What astronomers were particularly keen to see what happened after the comet reached perihelion – its closest approach to the Sun – on 8 December 2019.

That’s because there are two types of comets in the Solar System. Short-period comets typically come from the Kuiper Belt or closer, and have an orbital period of less than 200 years. They are much more likely to stay intact when they go past the Sun.

Long-period, or dynamically new comets come from farther away – the Oort cloud – and are more likely than short-period comets to break up. Analyses of 2I/Borisov’s colour and composition found it was very similar to long-period comets, so disintegration due to heating from the Sun was anticipated, but not guaranteed.

“For Solar System comets, it is known that dynamically new comets are 10 times more likely to disintegrate than short-period comets, presumably due to their pristine state and weaker structural strength,” wrote researchers led by Quanzhi Ye from the University of Maryland last year.

This would be seen as a change in brightness in the comet – and indeed, this is what has been observed. Between 5 and 9 March 2020, the comet brightened twice.

But although it may be the end of the line for 2I/Borisov – a journey of an unconfirmed number of light-years across space – it’s not a sad one. As the comet disintegrates, observations of its spectrum will reveal its internal chemistry, including its nucleus.

It’s an excellent opportunity to study the comet’s guts, and compare it to our Solar System comets, to see how similar or different they are.

Since comets are thought to be a vital part of the emergence of life here on Earth, those comet guts could help us discover if the ingredients for life are common in our galaxy.

So astronomers will be continuing to closely monitor 2I/Borisov’s activity.

See the full article here .

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From Science Alert: “NASA Suspends Work on The New Moon Mission Rocket Due to Coronavirus Outbreak”

From Science Alert

23 MARCH 2020

NASA said it has suspended work on building and testing the rocket and capsule for its Artemis crewed mission to the Moon due to the rising number of coronavirus cases in the community.

NASA ARTEMIS spacecraft depiction

The Lockheed Martin-built Orion capsule for the Artemis 1 mission to the Moon is declared finished. https://techcrunch.com

The space agency is shutting down its Michoud Assembly Facility in New Orleans, where the Space Launch System rocket is being built, and the nearby Stennis Space Center, administrator Jim Bridenstine said late Thursday.

“The change at Stennis was made due to the rising number of COVID-19 cases in the community around the center, the number of self-isolation cases within our workforce there, and one confirmed case among our Stennis team,” he said.

“NASA will temporarily suspend production and testing of Space Launch System and Orion hardware. The NASA and contractors teams will complete an orderly shutdown that puts all hardware in a safe condition until work can resume.”

The Space Launch System is a powerful deep space rocket to transport astronauts to the Moon and beyond while Orion is the crew module.

The virus outbreak could hit US plans to return to the Moon by 2024.

“We realize there will be impacts to NASA missions, but as our teams work to analyze the full picture and reduce risks we understand that our top priority is the health and safety of the NASA workforce,” Bridenstine said.

A crewed return to the Moon is the first part of the Artemis program to set up a long-term colony and test technologies for a crewed mission to Mars in the 2030s.

See the full article here .

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From Science Alert: “Giant Freshwater Reserve Discovered Deep Under The Seabed Off New Zealand”

From Science Alert

22 MARCH 2020
DAVID NIELD

(Diane Keough/Moment/Getty Images)

A rare freshwater reserve has been discovered underneath the sea off the coast of the South Island of New Zealand, which could help head off future droughts and mitigate the impact of climate change in the coming years.

The offshore freshened groundwater (OFG) was discovered through a combination of seismology and electromagnetic wave scanning techniques, which were used to build up a 3D map of the aquifer under the sea.

While the precise water capacity has yet to be calculated, the researchers think the system could be holding as much as 2,000 cubic kilometres (or nearly 480 cubic miles) of freshwater – that’s 800 million Olympic-sized swimming pools, or more than Lake Ontario.

How the freshwater reserve formed. (Marcan)

These offshore aquifers, locked in rock, can be found in various spots around the world, though they’re not very common. In this case, much of the water is likely to have been left behind by the last three ice ages, the scientists say.

“One of the most important aspects of this study is the improved understanding it offers to water management,” says marine geologist Joshu Mountjoy, from the National Institute for Water and Atmospheric Research (NIWA) in New Zealand.

“At the moment we have used remote techniques, modelling and geophysics. We really need to go out there and ground-truth our findings and we are investigating options for that.”

The first hint that such an OFG system was hidden off the port city of Timaru was brackish water (a mix of saltwater and freshwater) discovered after a scientific drilling project in 2012.

Further investigation was started on board a research vessel in 2017. The aquifer is unusually shallow, just 20 metres (less than 66 feet) below the sea floor. It is thought to extend around 60 kilometres (37 miles) away from the coastline.

Its location is particularly fortunate, with the wider Canterbury region facing increased pressure from a growing population and extended dry periods. The vast freshwater reservoir could account for half the groundwater in Canterbury, the researchers say.

While detailed maps of water salinity and aquifer shape have now been drawn up, plenty of unknowns remain. Next, the team wants to actually take samples from the freshwater system and compare them to the models so far.

According to the researchers, the same techniques applied in this study could also be used to re-evaluate similar aquifers across the globe.

Local authorities are keen to explore how the newly discovered aquifer could help with freshwater supplies, without any damage to the surrounding environment or to the ecosystems that depend on it.

“As far as long-term resilience for both our communities and economy, the Timaru district is currently looking at options for long term water security,” Timaru mayor Nigel Bowen told Lee Kenny at Stuff.

“Water is our number one priority to get right for our future generations.”

The research has been published in Nature Communications.

See the full article here .

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From Science Alert: “Scientists Recommend These 4 ‘Weapons’ in Our War Against Climate Change”

From Science Alert

16 MARCH 2020
DAVID BLAIR ET AL.

(Gentrit Murati/Unsplash)

In 1896, Swedish scientist Svante Arrhenius explored whether Earth’s temperatures were influenced by the presence of heat-absorbing gases in the atmosphere. He calculated that if carbon dioxide concentrations doubled, global temperatures would rise by 5°C – even more at the poles.

Just over a century later, the world is on track to fulfilling Arrhenius’ prediction. If we continue on the current trajectory, Earth will warm up to 4.8°C above pre-industrial times by 2100.

We are a group of experts in physics, geology, science education, coral reefs and climate system science. We believe the lack of progress by governments in reducing global emissions means bold solutions are now urgently needed.

We must fight climate change like it’s World War III – and battle on many fronts. Here we examine four of them.
1. Plant a lot more trees

Tree-planting has enormous potential to tackle to climate crisis. Recent research calculated that worldwide 900 million hectares of additional tree cover could exist outside of already-established forests, farmland and urban areas – sufficient to store 25 percent of the current atmospheric carbon pool. Forests act to increase cloud and rainfall and reduce temperatures.

The grand vision of the Gondwana link project in Western Australia is an example of what can be done. It is reconnecting fragmented ecosystems to create a continuous 1,000 kilometre corridor of bushland.

Broadscale land clearing must cease and a massive program of tree planting should be implemented in all possible areas. Such a program would provide huge small business employment opportunities. It requires incentives and partnerships that could be funded through taxes on carbon emissions.

Renewable energy-powered desalination may be required in some places to provide the water needed to establish forests in drought conditions. This meshes with an important new technology: carbon mineralisation.

2. Turn carbon dioxide into rock

Carbon mineralisation involves turning carbon dioxide into carbonate minerals by emulating the way seashells and limestone are made naturally.

Many techniques have been researched and proposed. These include capturing carbon dioxide from industrial plants and bubbling it through brine from desalination plants, or capturing it from nickel mine tailings using bacteria.

Huge quantities of CO2 can potentially be captured in this way, creating useful building materials as a by-product.

Demonstration plants should now be trialled in Australia, with a view to rapid scaling up to commercialisation.

3. Make Earth’s surface more reflective

Solar radiation management describes techniques to reflect solar energy (sunlight) back to space, and so counteract planetary heating.

Changing the reflectivity of surfaces, such as by painting a dark roof white, reduces absorbed heat enormously and could cool cities. On larger scales we can dust asphalt roads with limestone, retain pale stubble on farms over summer and plant paler crops.

Studies suggest lighter land surfaces have good potential for cooling at a regional scale, and may lower extreme temperatures by up to 3°C.

Such methods also indirectly cut greenhouse gas emissions by reducing air-conditioner use.

4. Reimagine transport

Economic mechanisms are essential to accelerate the transition to renewable energy, energy storage and zero-emission transport.

The international shipping industry emitted about 800 megatonnes of carbon dioxide in 2015, and this figure is expected to double by mid-century.

For all ships not powered by renewable energy, research suggests speed limits could be lowered by 20 percent to reduce fuel use. Australia could lead the world by scaling berthing charges according to satellite-monitored ship speeds.

Australia should also follow the lead of Norway which offers generous financial incentives to encourage zero-emission vehicles (powered by hydrogen or electricity). These include sales tax exemption and free parking in some places. And it’s worked: almost 60 percent of new cars sold in Norway in March 2019 were reportedly entirely electric-powered.

Where to next?

The above list is by no means exhaustive. Australia’s bid to sell emissions reduction to the world as renewable hydrogen and electricity should be massively accelerated, and expanded to the scale of the Apollo mission’s race to the Moon.

We must slash emissions from agriculture, and re-establish soil carbon reservoirs lost through modern agriculture. We also suggest a major military response to bushfire, including a water-bombing air fleet and airfields within two hours of every fire risk location.

Finally, the war demands a central headquarters providing leadership, information and coordination – perhaps a greatly expanded version of the Greenhouse Office established under the Howard Coalition government in 1998 (but later merged into another government department). The office should provide, among other things, information on the climate cost of every item we use, both to aid consumer choice and tax climate-harming products.

Some technologies may prove too costly, too risky, or too slow to implement. All require careful governance, leadership and public engagement to ensure community backing.

But as global greenhouse gas emissions continue to grow, governments must deploy every weapon available – not only to win the war, but to prevent the terrible social cost of despair.

The full report on which this article is based is available here.

See the full article here .

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From Science Alert: “The Supermassive Black Hole at The Centre of Our Galaxy Is Becoming More Active”

From Science Alert

17 MARCH 2020
MICHELLE STARR

Chandra view of Sgr A*. (NASA/CXC/MIT/F. Baganoff, R. Shcherbakov et al.)

Sagittarius A*, the supermassive black hole at the centre of the Milky Way, isn’t exactly rowdy. It’s not classified as an active galactic nucleus – one of those galactic cores that glow exceedingly brightly as they feast on copious amounts of material from the surrounding space.

However, the brightness of our galaxy’s centre does fluctuate a little across the electromagnetic spectrum on a daily basis. Astronomers have now confirmed that, over the last few years, Sgr A*’s most energetic X-ray flares have been increasing.

The paper has been accepted in the journal Astronomy & Astrophysics, and is already available on arXiv while it undergoes the peer review process. The results support the conclusions of earlier studies that have found our galactic centre is indeed getting restless.

Specifically, a team of French and Belgian researchers led by astrophysicist Enmanuelle Mossoux of the University of Liège in Belgium continued their work from a 2017 paper that found the rate of bright flares had increased threefold from 31 August 2014.

The earlier work – also co-authored by Mossoux – studied X-ray data on Sgr A* from the XMM-Newton, Chandra and Swift observatories collected between 1999 and 2015. They detected 107 flares in total. Not only were the brightest X-ray flares increasing after August 2014, the faintest ones had decreased from August 2013.

ESA/XMM Newton

NASA/Chandra X-ray Telescope

NASA Neil Gehrels Swift Observatory

To find out if these trends have continued, Mossoux and colleagues collected and analysed the data from all three telescopes between 2016 and 2018. They detected 14 more flares to add to the previous data for a total of 121.

Then, they analysed all the flares, using the previous methods, and revised methods to determine the flare rate and distribution. These found that one of the earlier conclusions was incorrect – there was no decrease in the rate of faint flares; these remained pretty steady over the period covered by the data.

“However, this did not change our global result: a change in flaring rate is found for the brightest and most energetic flares at the same date as was found in the previous section,” the researchers wrote in their paper.

Although these studies both only refer to X-ray flaring, they’re not the only hint in recent times that something is up with Sgr A*. Last year, the black hole flared 75 times its usual brightness in near-infrared – the brightest we’ve ever observed it in those wavelengths.

The team analysing the near-infrared observations had a dataset of 133 nights from 2003; and last year, they found three nights on which Sgr A* near-infrared activity was elevated. They said in their paper that this was “unprecedented compared to the historical data.”

(Don’t worry, Sgr A* is 26,000 light-years away. The big bad black hole can’t get you.)

Mossoux and her team have also checked to see if the 2019 activity is consistent with their recent findings. They analysed the Swift data from 2019, and found four bright flares, the largest number ever observed in a single campaign, confirming that the black hole is not settling down.

Additionally, XMM Newton and Chandra data from 2019 – due for release this year – could reveal even more about the peculiar X-ray activity, and what might be causing it – whether it’s accretion, or something else, such as the tidal disruption of passing asteroids.

Observations across other wavelengths could reveal more information too. Continued observations in the near-infrared, and radio wave observations, could help us figure out what’s making Sgr A* stir.

“Since 2014, the activity of Sgr A* thus increased in several wavelengths,” the researchers wrote.

“Additional multiwavelength data are required to conclude on the persistence of this increase and to obtain clues on the source of this unprecedented activity of the supermassive black hole.”

See the full article here .

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From Science Alert: “Ancient Supermassive Black Hole Has Its Particle Beam Aimed Right at Earth”

From Science Alert

12 MARCH 2020
PETER DOCKRILL

Artist’s concept of Active Galactic Nucleus. (NASA/Goddard Space Flight Centre Conceptual Image Lab)

Astronomers have discovered the existence of a supermassive black hole that looks to be the oldest and most distant of its kind we’ve ever encountered – and it just happens to be aiming its bright particle beam directly at Earth.

The newly found supermassive black hole – called PSO J030947.49+271757.31 – is the most distant blazar ever observed, researchers say. That conclusion is based on the wavelength signature of the object’s redshift, a phenomenon scientists can use to measure the distance of light-emitting sources in space.

Blazars are supermassive black holes that lie at the heart of active galactic nuclei: central regions of galaxies bursting forth with high levels of luminosity and electromagnetic emissions, thought to occur due to the intense heat generated by particles of gas and dust swirling in the accretion disks of supermassive black holes.

Amongst these brilliant objects, blazars are the brightest of all – depending on your perspective, at least. The term ‘blazar’ is reserved for supermassive black holes where the jet of radiation is angled towards Earth, which makes it handy for astronomers to analyse these distant black holes in greater detail.

“The spectrum that appeared before our eyes confirmed first that PSO J0309+27 is actually an active galaxy nucleus, or a galaxy whose central nucleus is extremely bright due to the presence in its centre of a supermassive black hole fed by the gas and the stars it engulfs,” says astrophysicist Silvia Belladitta from the University of Insubria in Italy.

“In addition, the data obtained by the Large Binocular Telescope (LBT) also confirmed that PSO J0309+27 is really far away from us, according to the shift of the colour of its light toward red or redshift with a record value of 6.1, never measured before for a similar object.”

LBT-U Arizona Large Binocular Telescope, Large Binocular Telescope Interferometer, or LBTI, is a ground-based instrument connecting two 8-meter class telescopes on Mount Graham, Arizona, USA, Altitude 3,221 m (10,568 ft.) to form the largest single-mount telescope in the world. The interferometer is designed to detect and study stars and planets outside our solar system. Image credit: NASA/JPL-Caltech.

Based on their readings, astronomers say the light we can detect from PSO J0309+27 was actually emitted almost 13 billion years ago, meaning the blazar existed in the extremely early stages of the Universe, less than a billion years after the Big Bang.

While thousands of blazars have been found to date, the exceptional distance and age of PSO J0309+27 makes it a remarkable outlier – but that doesn’t mean the object is entirely unique.

Because blazars happen to be pointed right at us, we have the opportunity to better analyse their beams. Similarly bright active galactic nuclei – called quasars – are inclined at different angles, so their particle beams are more likely to remain hidden from us.

“Observing a blazar is extremely important,” Belladitta explains. “For every discovered source of this type, we know that there must be 100 similar, but most are oriented differently, and are therefore too weak to be seen directly.”

This inferred population remains firmly hypothetical for now, but the discovery of PSO J0309+27, which the team estimates to have a mass equal to about 1 billion times the mass of the Sun, is a big deal. Having found PSO J0309+27, it tells us that these giant, powerful objects existed in the early stages of the Universe, and likely in great numbers.

The team acknowledges further observations are needed to narrow down just how sizeable this hypothetical black hole population might be. In any case, we’re looking at an object that’s big, important, and new to science; when you’re studying supermassive black holes, no discovery is trifling.

“Thanks to our discovery, we are able to say that in the first billion years of life of the Universe, there existed a large number of very massive black holes emitting powerful relativistic jets,” Belladitta says.

“This result places tight constraints on the theoretical models that try to explain the origin of these huge black holes in our Universe.”

The findings are reported in Astronomy & Astrophysics.

See the full article here .

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