Space: The Final Frontier

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Return to the Moon will have to wait

Lofty ambitions for future space exploration have been brought back down to Earth.

The pandemic, technical difficulties, and a lack of cash means planned return missions to the Moon will be delayed.

NASA has revealed “significant challenges” leading to a delay in the development of the spacesuits needed for the journey. Australian companies are vying for the chance to play a role in the Moon to Mars missions. Adelaide’s Human Aerospace, for example, has been working on next-generation spacesuits.

According to the audit report from NASA’s Office of Inspector General, NASA has been working on Exploration Extravehicular Mobility Units (xEMU) for 14 years. The spacesuits are being designed for use on the International Space Station as well as the Artemis mission.

The Artemis mission aims to return astronauts – including the first woman and the first person of colour – to the Moon by 2024. It’s the first part of a larger mission to establish a lunar gateway in orbit as a base from which to send people to Mars.

According to the latest report, the suits will not be ready for flight until at least 2025.

“This schedule includes approximately a 20-month delay in delivery for the planned design, verification and testing suit, two qualification suits, an ISS demo suit and two lunar flight suits,” the OIG reported.

“These delays – attributable to funding shortfalls, COVID-19 impacts, and technical challenges – have left no schedule margin for delivery of the two flight-ready xEMUs.

“Given the integration requirements, the suits would not be ready for flight until April 2025 at the earliest. Moreover, by the time two flight-ready xEMUs are available, NASA will have spent over a billion dollars on the development and assembly of its next-generation spacesuits.”

That delay – and other delays outlined in the report – means a 2024 lunar landing is no longer feasible.

NASA has known for some time that the 45-year-old suits in use on the ISS needed updating. The new design will accommodate a broader range of sizes, and a more mobile lower torso for walking, which it says will eliminate the “bunny hopping” famously seen during the Apollo missions.

Along with improved mobility, they will have a more advanced life support system to remove carbon dioxide, odours and humidity, and to maintain body temperature.

They will have a new pressure subsystem to keep astronauts alive in the vacuum of space and protect them from micrometeoroids and space debris, as well as liquid cooling and ventilation garments.

The informatics subsystem will have high-definition video, data recording, and other technical advantages over the current suits. The new suits will also need to interface with the new vehicles that will be used.

The US Congress has only approved three-quarters of the $209 million budget for the suits. Meanwhile, facility closures and work restrictions due to the pandemic added to delays.

On top of those delays, various component failures and a lack of contingency plans mean the lunar landing will not happen on time.

https://cosmosmagazine.com/space/exploration/return-to-the-moon-will-have-to-wait/

 

[nudge]

9 minutes ago, CaaC (John) said:

 

As expected. 

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Astronomers see galaxies in ultra-high definition

Astronomers have captured some of the most detailed images ever seen of galaxies in deep space.

They are in much higher definition than normal and reveal the inner workings of galaxies in unprecedented detail.

Many of the images could yield insights into the role of black holes in star and planet formation.

The researchers say that the pictures will transform our understanding of how galaxies evolve.

The images are of the radio waves emitted by the galaxies. Researchers often study the radio waves from astronomical objects rather than the visible light they give off because it enables them to see things that would otherwise be blocked by the Earth's atmosphere or dust and gas in faraway galaxies.

Many regions of space that are dark to our eyes, actually burn brightly in the radio waves they give off. This allows astronomers to peer into star-forming regions or into the heart of galaxies.

What is new is that the team has dramatically improved the resolution of radio images by linking together more than 70,000 small antennae spread across nine European counties.

Combining radio signals from so many antennas is not a straight-forward process. The team has spent six years developing a completely new way of collecting the signal from each antenna, digitising it, transporting it to a to central processor, and then combining all the data into images that are not only of enormous scientific interest but also of great beauty.

The accomplishment is a technical tour de force and was led by Dr Leah Morabito from Durham University, UK.

"To work on the data for so long, and then to finally get such images and be able be the first person to see what it looks like is just incredible," she told BBC News.

"I walked around with a huge smile on my face for the rest of the day, because I felt so proud that I was able to make these images and be able to see something nobody had ever seen before".

The image at the top of the page was produced by a member of Dr Morabito's team. It shows a galaxy that is barely visible, sitting in the middle of jets of material in orange, shooting out from either side, each one much larger than the galaxy itself.

The jets are caused by a supermassive black hole at the heart of the galaxy- an object with such strong gravity not even light can escape. It normally sucks in material - but the inward pull also creates forces around the black hole that result in material being spat out, far into space.

Such jets have been observed before - but astronomers have obtained new scientific information from the dark bands on the jet on the right, which have not been seen before. These, the astronomers believe, represent periods of relative inactivity by the black hole - when it spits out less material. The image therefore gives researchers an insight into the black hole's "sleep cycle".

The picture above shows two galaxies colliding. the bright spot on the one on the left is caused by exploding stars - creating what is effectively a galactic wind - blowing dust and gas away from it.

The light from the galaxy shown directly above originated when the Universe was only 2.6 billion years old. Above and below it are jets of material thrown out by the black hole within. Normally such early galaxies can't be studied in detail. But now, for the first time, the astronomers have seen the structure of one of them at radio frequencies - which provides critical scientific information about how the black hole is interacting with its surroundings.

The images are revealing that galaxies are much more than a collection of stars. They are dynamic sun- and planet-making factories, powered by black holes, according to Dr Neal Jackson, from the University of Manchester.

"Even seasoned astronomers go 'wow!' when they see these images," he told me.

"It's become very clear that, in order to understand galaxy evolution, we need to understand the black hole right at the very centre, because it appears to have a fairly fundamental influence on how galaxies evolve and that is what these images allow us to do," says Dr Jackson.

"These high-resolution images allow us to zoom in to see what's really going on when supermassive black holes launch these jets of material."

Dr Morabito says that images like these are helping astronomers learn just how these processes, that created stars and planets - including our own Solar System - actually work.

"We are really beginning to understand how galaxies have evolved. And the black holes are a massive part of that because their jets can take away fuel for star formation. And as they push outwards, they can disrupt the galaxies. They can even trigger star formation or quench it and make it happen less," she said.

The first set of results have led to the publication of nine scientific papers on the dynamics of black holes in galaxies. But this is just the start for the team. They plan to scan millions of galaxies over the next few years.

"And that's really what we need to be able to understand, the whole complete picture of how black holes impact galaxy evolution," says Dr Morabito,

"I think we're definitely in for some surprises. Whenever you start doing something new in astronomy you always find out things that you never expected and that's what I really look forward to."

The international network of telescopes is known as the Low Frequency Array known as Lofar for short. Most of the antennas are located in Exloo in the Netherlands.

https://www.bbc.co.uk/news/science-environment-57998940

 

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Could black holes power alien civilisations?

Building energy-harvesting structures around black holes could be effective, scientists say.

For centuries, humans have gazed up and wondered if we are alone in the universe. In 1960, physicist Freeman Dyson changed the conversation by suggesting some cool celestial tech that would allow us to more easily detect signs of alien civilisations.

Dyson suggested that if an alien society’s energy needs outstripped the supply of its planet, it could build a megastructure known as a ‘Dyson sphere’ around its host star to harness the power on a massive scale. Not technically a sphere, this structure would be composed of a fleet of orbiting or stationary satellites able to transform solar energy into usable energy.

This would make it easier for us to find such civilisations, Dyson argued, as the process could create waste heat and therefore abnormal infrared signals.

Now, in a new paper published in the Monthly Notices of the Royal Astronomical Society, scientists say these spheres could be even more ambitious – aliens could build them around black holes, too.

The research team, led by astronomer Tiger Yu-Yang Hsiao of National Tsing Hua University in Taiwan, delved into the physics behind some excitingly high-concept questions: How would a Dyson sphere around a black hole work? How much energy could it gather, and for what type of alien society? Could we detect such a structure from Earth?

In particular, the team looked at hypothetical technologically advanced alien civilisations (Type II or III, according to the Kardashev scale).

“They need a more powerful energy source than their own sun,” the researchers write in the study.

Of course, nothing escapes the monstrous gravitational pull of a black hole, but the team considered energy-intense processes beyond the event horizon – where a super-hot disc of matter swirls around the black hole like water around a cosmic drain.

By looking at models of various-sized black holes (from a little more than our sun’s mass right up to the mass of the supermassive monster at the heart of our galaxy), they found that a sphere of satellites could effectively gobble up energy from many of these processes.

“Our results suggest that for a stellar-mass black hole…the accretion disc could provide hundreds of times more luminosity than a main sequence star,” they write.

For an even bigger black hole of 20 solar masses, they report it could provide the same amount of power as Dyson spheres around 100,000 normal stars – and the number soars to one million for a supermassive black hole.

And that’s just the power harnessed from the accretion disc.

“Moreover, if a Dyson sphere collects not only the electromagnetic radiation but also other types of energy (e.g., kinetic energy) from the [relativistic] jets, the total collected energy would be approximately five times larger,” the researchers write.

But would these Dyson spheres be detectable by earthly technology?

Hsiao and the team calculate that if this tech existed around a stellar-mass black hole within our galaxy, we could spot its ‘waste’ heat at ultraviolet, optical and infrared wavelengths. It could be detectable by current telescopes such as Hubble, or large surveys such as the Sloan Digital Sky Survey or the Wide-field Infrared Survey Explorer.

But the team cautions that since black holes emit a lot of radiation, signals from a Dyson sphere would risk being lost in the noise.

They suggest observations could be confirmed via the radial velocity method, currently used to detect exoplanets by spotting the minute gravitational wobble of their stars.

https://cosmosmagazine.com/science/physics/dyson-spheres-around-black-holes/

 

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How you can see Jupiter in opposition tonight

Tonight, 19 August, is your best opportunity to see the king of the Solar System – no telescope required.

August is quite often one of the quieter months in the astronomical calendar. With the Sun setting later through the summer months, it can make fainter objects challenging to observe.

The plus side is that warm weather makes it the perfect time for beginners to get to know the night sky without winter coats and woolly hats, however.

A particular gem is the king of the Solar System: Jupiter, which comes into opposition on 19 August.

As the outer planets orbit around the Sun, Earth occasionally finds itself between the Sun and another planet, with all three in direct alignment. When this happens, we describe it as a planet being in opposition.

Oppositions occur roughly annually (with Mars being the exception, at 27 months) and can often provide the best opportunity to observe and photograph the particular planet because of its favourable position and brightness.

At Jupiter’s opposition, Earth will lie directly in between Jupiter and the Sun. It will appear bigger and brighter than usual as it’s also when Earth and Jupiter’s orbits are closest together (known as perigee).

Looking south at 1:20am BST on 20 August © Pete Lawrence

From around 9:14pm, Jupiter will begin to rise in the eastern constellation of Capricorn, just 7° above the horizon. As the night progresses, it will climb until it reaches its highest point, 24° above the horizon at 12:20am (so you won’t need to stay up too late to enjoy it).

As dawn approaches, it will slowly descend, disappearing below the horizon at approximately 4:56am.

For naked-eye observers, Jupiter will appear as a very bright point of light that, unlike stars, does not twinkle. A decent set of binoculars (7×10 magnification) will provide you with a view of Jupiter’s four largest moons, Ganymede, Europa, Callisto and Io, and a telescope will allow you to view Jupiter’s stripes.

https://www.sciencefocus.com/space/jupiter-in-opposition-uk/

 

Stellarium

 

Edited August 21, 2021 by CaaC (John)
Insert - Stellarium

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Disintegrating comet was seen by ancient civilisations

A modern comet’s demise hints at spectacular show 5,000 years ago.

This pair of Hubble Space Telescope images of comet C/2019 Y4 (ATLAS), taken on April 20 and April 23, 2020, reveal the breakup of the solid nucleus of the comet. Hubble photos identify as many as 30 separate fragments. The comet was approximately 91 million miles from Earth when the images were taken. The comet has been artificially colored in this view to enhance details for analysis. Credits: Science: NASA, ESA, Quanzhi Ye (UMD); Image Processing: Alyssa Pagan (STScI)

 

Researchers in the US have wound back the cosmic clock to determine that a spectacular comet whizzed past the Earth 5,000 years ago.

While the event isn’t recorded in any historical account, the team were able to gather clues from more recently sighted comets.

In a paper published in the Astronomical Journal, they examined observations made by the Hubble Space Telescope of the comet ATLAS (C/2019 Y4), which Hubble watched break into pieces last year.

This comet is thought to a fragment of a larger one that passed by the Earth in 1844, shining as brightly as Sirius, the brightest star in the sky.

By tracing the two comets’ motions back through time, the researchers figured out that they are likely both parts of an even bigger one that last zipped through the inner Solar System 5,000 years ago, around the time that Ancient Egyptians were first settling into the Nile valley.

The comet is like a Russian nesting doll – breaking into smaller and smaller pieces as it whizzes in huge orbits through the Solar System.

On its trip 5,000 years ago, it would have come within 37 million kilometres of the Sun, closer even than the orbit of Mercury.

But a mystery remains. The comet ATLAS observed by Hubble last year disintegrated when it was still a long way away from the Sun – 160 million kilometres distant. This is a bit “weird”, notes lead author Quanzhi Ye of the University of Maryland in College Park, US.

“If it broke up this far from the Sun, how did it survive the last passage around the Sun 5,000 years ago?” says Ye. “It’s very unusual because we wouldn’t expect it. This is the first time a long-period comet family member was seen breaking up before passing closer to the Sun.”

Ye’s new paper describes how one bit of ATLAS disintegrated in just days, while another lasted for weeks. One possible explanation for this is that centrifugal forces (driven by its ejected material) tore the comet apart, or perhaps it contained super-volatile ices that blew it apart like a firework.

“It is complicated because we start to see these hierarchies and evolution of comet fragmentation,” Ye says. “Comet ATLAS’s behaviour is interesting but hard to explain.”

The last surviving sibling of this comet family (the bit that passed in 1844) won’t visit Earth again for nearly 3,000 years.

https://cosmosmagazine.com/space/astronomy/disintegrating-comet-seen-ancient-civilisations/

 

[Stan]

Love it 

 

 

So much detail. Enjoyed picking out all the landmarks and stadia.

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Astronomy Picture of the Day

2021 August 25

Solar System Ball Drop
Video Credit & Copyright: James O'Donoghue (JAXA) & Rami Mandow (Space Australia); Text: James O'Donoghue

Explanation: Does a ball drop faster on Earth, Jupiter, or Uranus? The featured animation shows a ball dropping from one kilometer high toward the surfaces of famous solar system bodies, assuming no air resistance. The force of gravity depends on the mass of the attracting object, with higher masses pulling down with greater forces. But gravitational force also depends on distance from the center of gravity, with shorter distances causing the ball to drop faster. Combining both mass and distance, it might be surprising to see that Uranus pulls the ball down slightly slower than Earth, despite containing over 14 times more mass. This happens because Uranus has a much lower density, which puts its cloud tops further away from its center of mass. Although the falling ball always speeds up, if you were on the ball you would not feel this acceleration because you would be in free-fall. Of the three planets mentioned, the video demonstrates a ball drops even faster on Jupiter than either Earth and Uranus.

https://apod.nasa.gov/apod/astropix.html

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New class of exoplanet could put search for ET into hyper-drive

Until now, the search for extra-terrestrial life has been focused on planets like ours. But the hunting ground just expanded.

Astronomers have identified a new class of exoplanet they believe could be a candidate for the search for extra-terrestrial life, according to a new study in The Astrophysical Journal.

Traditionally, the search for extra-terrestrial life has focused on the terrestrial: looking for other “Earths” with similar dimensions and conditions. The planets in question, however, dubbed “Hycean” exoplanets by the authors of the paper, are hot, ocean-covered planets with hydrogen-rich atmospheres, and which are both more numerous and larger than Earth-like planets.

The researchers, from the University of Cambridge, UK, believe that despite being hotter than Earth, these planets could host large oceans that could in theory host microbial life similar to that found in Earth’s more extreme aquatic environments.

By modelling the atmospheres of various types of Hycean worlds, the team established that the planets allow for a far wider habitable zone (the “Goldilocks Zone”, the orbit around the planet’s star that’s the right temperature for life) than Earth-like planets.

“Hycean planets open a whole new avenue in our search for life elsewhere,” says lead author Nikku Madhusudhan, from Cambridge’s Institute of Astronomy.

“It’s a really important reminder that we need to keep exploring what could be rather than just focusing on the things that we definitely know,” says Jonti Horner, an astronomer at the University of Southern Queensland who was not involved in the study.

“One of the problems we have in astrobiology is that no matter how diverse life on Earth is, it’s only one kind of life – it’s Earth life,” Horner says. “And so we’re really strongly biased to think that the place you must look to find life must be a place like Earth.”

Mini-Neptunes and Super-Earths

There are thousands of exoplanets (planets outside our solar system) that are already known to science. Most of these are mid-size between Earth and Neptune and are thus called, perhaps uncreatively, either mini-Neptunes or super-Earths.

Most of these mini-Neptunes are around 1.6 times the size of Earth, and were thought to be far too hot and pressurised for life, thanks to their hydrogen-rich atmospheres.

But when Madhusudhan and his team conducted a recent study on mini-Neptune K2-18b, they found, perhaps surprisingly, that under certain conditions the planet could theoretically support life similar to the life found on Earth. Buoyed by this finding, the team began to investigate the various conditions under which mini-Neptunes could feasibly host life, leading them to develop the Hycean planet theory.

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Read more: Rocky exoplanet found in habitable zone of star next door

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These Hycean planets could be up to 2.6 times larger than Earth, and could have atmospheric temperatures as high as 200C. But their oceans may have conditions closer to those on Earth, and could be a place to start looking for life.

Hycean exoplanets may be a dime a dozen

The astronomers believe Hycean worlds are likely very common: more so than the Earth-like planets ET-enthusiasts have tended to search for. This means Hycean worlds open up the possibility of analysing far more planets, and potentially hastening the discovery of extra-terrestrial life, if it is indeed out there.

Identifying Hycean exoplanets requires more than just establishing their size, however: astronomers need to determine the habitable zone of the parent star, and search for molecular signatures that betray the planet’s atmosphere and structure.

Then, they will look for signs of life, bio-signatures including oxygen, ozone, methane and nitrous oxide, which are all present on Earth and could be the by-products of living organisms. Other bio-signatures will be considered, including methyl chloride and dimethyl sulphide, both of which are less abundant on Earth but could be promising signals on hydrogen-rich planets.

“Essentially, when we’ve been looking for these various molecular signatures, we have been focusing on planets similar to Earth, which is a reasonable place to start,” says Madhusudhan. “But we think Hycean planets offer a better chance of finding several trace biosignatures.”

The team have already identified a sample of potential Hycean worlds which could be prime candidates for future study. These planets all orbit red dwarf stars between 35-150 light-years away which, by astronomical standards, is practically in our backyard. The James Webb Space Telescope, due to launch this year, will observe the most promising candidate – K2-18b – once it becomes operational.

“A biosignature detection would transform our understanding of life in the universe,” says Madhusudhan. “We need to be open about where we expect to find life and what form that life could take, as nature continues to surprise us in often unimaginable ways.”

https://cosmosmagazine.com/space/astrobiology/new-class-hycean-exoplanet-discovered/

 

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Galaxies expel murkier gas than they take in

Galaxies take in fresh gas but fart out a complicated concoction.

VIDEO

Credit: James Josephides, Swinburne Astronomical Productions.

The outflow of galaxies is much dirtier than the gas that goes into them, according to research by an international team of astronomers.

The research, published in The Astrophysical Journal, examines the ‘accretion’ and ‘outflow’ of galaxies – the atoms that flow in, and the atoms that are eventually expelled.

“Enormous clouds of gas are pulled into galaxies and used in the process of making stars,” explains Deanne Fisher, associate professor at the Centre for Astrophysics and Supercomputing at Swinburne University, and co-author on the paper.

“On its way in, it is made of hydrogen and helium. By using a new piece of equipment called the Keck Cosmic Web Imager, we were able to confirm that stars made from this fresh gas eventually drive a huge amount of material back out of the system, mainly through supernovas.

“But this stuff is no longer nice and clean – it contains lots of other elements, including oxygen, carbon and iron.”

These heavier elements are formed in the centre of stars through nuclear fusion. When stars collapse in on themselves, or explode in supernovas, these elements are expelled.

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Read more: Did Betelgeuse supernova? Or was it just a dusty fart?

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 “We found there is a very clear structure to how the gases enter and exit,” says Dr Alex Cameron, co-author on the paper and now a researcher at the University of Oxford, UK.

“Imagine the galaxy is a spinning frisbee. The gas enters relatively unpolluted from the cosmos outside, around the perimeter, and then condenses to form new stars. When those stars later explode, they push out other gas – now containing these other elements – through the top and bottom.”

The researchers examined a galaxy called Mrk 1486, which is a ‘starburst’ galaxy – it is forming stars very rapidly. Mrk 1486 sits at an angle to Earth that makes it ideal for viewing both the accreting gases and the outflow.

“This work is important for astronomers because for the first time we’ve been able to put limits on the forces that strongly influence how galaxies make stars,” says Fisher.

“It takes us one step closer to understanding how and why galaxies look the way they do – and how long they will last.”

https://cosmosmagazine.com/space/astrophysics/galaxies-expel-murkier-gas-than-they-take-in/

 

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On 03/09/2021 at 04:40, CaaC (John) said:

 

 

@Stan @nudge whoever, could you delete this post, please, as it should have been posted in the Mars thread, I have now posted it in the Mars thread.  

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Our Universe may have a fifth dimension that would change everything we know about physics

What else could there be beyond the three dimensions of space and one of time? And how can we begin to conceive of it?

 

In 1905, Albert Einstein showed in his Special Theory of Relativity that space is intimately connected to time via the cosmic speed limit of light and so, strictly speaking, we live in a Universe with four dimensions of space-time. For everyday purposes however, we think of the Universe in three dimensions of space (north-south, east-west, up-down) and one dimension of time (past-future). In that case, a fifth dimension would be an extra dimension of space.

Such a dimension was proposed independently by physicists Oskar Klein and Theodor Kaluza in the 1920s. They were inspired by Einstein’s theory of gravity, which showed that mass warped four-dimensional space-time.

Since we’re unable to perceive these four dimensions, we attribute motion in the presence of a massive body, such as a planet, not to this curvature but to a ‘force’ of gravity. Could the other force known at the time (the electromagnetic force) be explained by the curvature of an extra dimension of space?

 

Kaluza and Klein found it could. But since the electromagnetic force was 1,040 times stronger than gravity, the curvature of the extra dimension had to be so great that it was rolled up much smaller than an atom and would be impossible to notice. When a particle such as an electron travelled through space, invisible to us, it would be going round and round the fifth dimension, like a hamster in a wheel.

Kaluza and Klein’s five-dimensional theory was dealt a serious blow by the discovery of two more fundamental forces that operated in the realm of the atomic nucleus: the strong and weak nuclear forces.

But the idea that extra dimensions explain forces was revived half a century later by proponents of ‘string theory’, which views the fundamental building blocks of the Universe not as particles, but tiny ‘strings’ of mass-energy. To mimic all four forces, the strings vibrate in 10-dimensional space-time, with six space dimensions rolled up far smaller than an atom.

String theory gave rise to the idea that our Universe might be a three-dimensional island, or ‘brane’, floating in 10-dimensional space-time. This raised the intriguing possibility of explaining why gravity is so extraordinarily weak compared with the other three fundamental forces. While the forces are pinned to the brane, goes the idea, gravity leaks out into the six extra space dimensions, enormously diluting its strength on the brane.

There is a way to have a bigger fifth dimension, which is curved in such a way that we don’t see it, and this was suggested by the physicists Lisa Randall and Raman Sundrum in 1999. An extra space dimension might even explain one of the great cosmic mysteries: the identity of ‘dark matter’, the invisible stuff that appears to outweigh the visible stars and galaxies by a factor of six.

In 2021, a group of physicists from Johannes Gutenberg University in Mainz, Germany, proposed that the gravity of hitherto unknown particles propagating in a hidden fifth dimension could manifest itself in our four-dimensional Universe as the extra gravity we currently attribute to dark matter.

Though an exciting possibility, it’s worth pointing out that there’s no shortage of possible candidates for dark matter, including subatomic particles known as axions, black holes and reverse-time matter from the future!

https://www.sciencefocus.com/space/fifth-dimension/

 

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Astronomy Picture of the Day

2021 September 5

VIDEO - YouTube

Earth and Moon
Image Credit: NASA, JPL, Galileo Project; Processing & License: Gordan Ugarkovic

Explanation: The Earth and Moon are rarely photographed together. One of most spectacular times this occurred was about 30 years ago when the Jupiter-bound Galileo spacecraft zoomed past our home planetary system. Then, robotic Galileo watched from about 15-times the Earth-Moon separation as our only natural satellite glided past our home world. The featured video combines 52 historic color-enhanced images. Although our Moon may appear small next to the Earth, no other planet in our Solar System has a satellite so comparable in size . The Sun, far off to the right, illuminated about half of each sphere, and shows the spinning Earth's white clouds, blue oceans, and tan continents.

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Forget rockets – a lunar elevator is the future of Moon travel

Blasting off in a rocket is an expensive, difficult and dangerous way to get to the Moon. Colin Stuart looks into another way we could travel there and back.

What do you see when you look at the Moon? Beauty? Craters? Some people see dollar signs. You’ll occasionally see our only natural satellite billed as ‘Earth’s eighth continent’ because it’s full of resources that are hard to ignore. A rare form of helium, helium-3, could be used in fusion power stations here on Earth. Rare elements, such as neodymium, could be extracted and returned home for use in smartphones and other electronics.

But how do we get them here without blowing all the profits on rockets? According to a study published in 2019, a lunar elevator could be the answer. A cable anchored to the lunar surface would stretch most of the 400,000km (250,000 miles) home. It couldn’t be directly attached to the Earth, due to the relative motions of the two objects, but it could terminate high in Earth orbit.

That would have the added benefit of placing it above the bulk of our space junk, a growing problem as we launch ever more satellites. Solar-powered robotic shuttles could move up and down the cable, acting as a conveyor belt to ferry precious resources our way.

It may sound like an outlandish prospect, but Zephyr Penoyre and Emily Sandford – the two University of Columbia astronomy PhD candidates behind the study – believe we could pull it off for a few billion US dollars.

To put that into context, Jeff Bezos liquidates $1bn (over £700m) of his Amazon stock every year to fund his Blue Origin space tourism company. NASA’s Artemis programme, which is sending the first female astronaut and first astronaut of colour to the Moon later this decade, is costing $86bn (£60bn). Such is the value of the Moon’s resources, a separate study estimated that a lunar elevator would pay for itself within just 53 trips.

The cable, which would be no thicker than a pencil, would weigh 40 tonnes – well within the remit of modern rockets, such as SpaceX’s Starship. Unlike a space elevator that would travel from Earth’s surface into space, a lunar elevator stopping slightly shy of our planet wouldn’t have to contend with huge gravitational forces.

The Moon has no atmosphere either, which simplifies matters. That means the cable could be made from existing materials, such as Kevlar, instead of the yet-to-be-invented super-strong materials needed for an Earth-to-space elevator.

We could also combine the two. In April 2021, Chinese state-run media presented the country’s idea for a ‘Sky Ladder’. This would see a spacecraft winched up an elevator from Earth’s surface to a waiting space station, before being flung towards the Moon where it would meet another elevator that would lower it down to the lunar surface.

The idea of space elevators has been around for over a century without much progress. But if enough people – or, more likely, corporations – become enamoured with the chance of making big bucks, we could see the lunar equivalent of a gold rush in the decades ahead. Elevators could well turn out to be a way to keep costs down and profits literally sky-high.

https://www.sciencefocus.com/space/lunar-elevator/

 

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Cosmology, next-gen

The last century has grown our understanding of the universe from speculation to precision science – and raised fundamental questions.

In the year 1909, a little-known astronomer named Vesto Slipher began a series of painstaking observations at the Lowell Observatory in Flagstaff, Arizona, in the US. The observatory had been built primarily to look for evidence of Martian canals, but Slipher had set his sights well beyond the Red Planet and its putative inhabitants. His interest was in the nature of fuzzy patches of light called nebulae. Were they gas clouds in the Milky Way, or far-flung galaxies in their own right? Slipher carefully measured the colour quality of the glowing patches, and found that the fainter they were, the redder their light. Through the lens of history, we can now see that this discovery marked the beginning of cosmology as a proper science.

Slipher’s “red shift” came to the attention of astronomer Edwin Hubble, who understood that the reddening effect implied that the objects were rushing away from us at great speed. Using a more powerful telescope, he confirmed that most of the nebulae were in fact distant galaxies. On 23 November 1924, Hubble announced in the New York Times that the entire universe is expanding. It was one of the most momentous scientific pronouncements of all time.

It took several more decades, however, before the modern big bang theory became established, according to which the universe was propelled on its path of expansion from an explosive origin 13.8 billion years ago. The intense heat of the primordial explosion still exists as a fading afterglow, filling all space with a sea of microwaves. This cosmic microwave background, or CMB, was detected by accident in 1967 by two radio engineers. It was immediately apparent that this was the big bang’s smoking gun, and that, etched into the structure of the CMB, lay vital clues about the origin and nature of the universe.

In November 1989, NASA launched the satellite COBE (Cosmic Background Explorer) to map the remnant primordial heat in detail. A few weeks later, NASA released the first heat map of the universe – a colour-coded palette of amorphous splodges indicating slightly hotter and colder patches of the sky. The golden age of cosmology had begun.

Over the three decades since, the CMB has been data-mined to enormous precision, first using COBE’s results, then those of other instruments, the most recent of which is the European Space Agency’s Planck satellite. Piecing together the CMB observations with those from powerful ground-based telescopes, astronomers and physicists have been able to construct the Great Story of the Universe from the first split second to today, in extraordinary detail. During my career, cosmology has gone from being a speculative backwater to a precision science.

In spite of this ringing success, some ugly cracks have started to appear in the cosmic facade. If theorists are to be believed, those tell-tale splodges in the CMB carry a faint echo of what the universe was doing a mere billion-trillion-trillionth of a second after the big bang, an era known as the inflationary phase, when the universe abruptly leapt in size by an enormous factor, as if it had taken a sudden deep breath. Quantum effects during inflation imprinted slight fluctuations in density and temperature on the nascent cosmos, sowing the seeds of what was to eventually evolve into the large-scale structure of the universe – galaxies and clusters of galaxies. The splodges in the CMB are evidently fossils from the edge of time itself, writ large and frozen in the sky.

The laws of quantum physics neatly explain the characteristic patterning observed by COBE and its successors, but there are a couple of discrepancies. The most glaring concerns a large patch in the Southern Hemisphere constellation of Eridanus which is weirdly much cooler than it should be based on statistical fluctuations. It looks like something has taken a giant bite out of the universe, leaving a supervoid. The Eridanus cold patch has led to some imaginative speculation. Could it be a blemish left by another universe bumping into our own? Might it be a portal into a region beyond the known universe? Or some sort of matter-destroying “bubble”?

Another fly in the cosmic ointment concerns the rate that the universe is expanding, known as Hubble’s constant. For decades astronomers sharply disagreed with the measurements, until a few years ago they agreed on a compromise value. Just as the dust was settling on this vexed issue, a new way to measure Hubble’s constant, using the splodges in the CMB, gave an answer seriously out of whack – about 10% smaller than the agreed number. Because the inferred age of the universe hinges on the value of Hubble’s constant, the implication is that 13.8 billion years is now an underestimate.

Dark matters of dispute

Next on the list of unanswered questions is the nature of dark matter and dark energy. Astronomers are certain that the stuff of which you, me and the stars are made is but a tiny percentage of all there is.

Fully five times as much matter is in some unknown form that doesn’t seem to interact noticeably with normal matter, except for the gravitational tug it exerts. The smart money is on some sort of weakly interacting heavy subatomic particle, legions of which must be passing through us all the time without causing a shudder. The race is on to try to detect the occasional fleeting passage of a dark matter particle, or perhaps to create one in giant accelerator machines like the Large Hadron Collider at CERN in Switzerland.

Even if a dark matter particle is nailed in the near future, it still leaves unanswered the nature of the stuff that makes up three-quarters of the mass of the universe, the thing known as dark energy. It is not really matter in the normal sense of the word. Rather, the best way to envisage dark energy is the energy of empty space (which is why we can’t see it).

The idea that space itself might have energy goes back to 1917, when Einstein realised that if the energy of space isn’t strictly zero then space would be self-repulsive; that is, it would possess an intrinsic propensity to expand, faster and faster. In effect, space energy is a form of anti-gravity. It wasn’t taken seriously until the 1990s when, low and behold, astronomers (including Brian Schmidt, now the Vice-Chancellor of ANU) found that the expansion of the universe is speeding up. Dark energy would do the trick nicely.

Not everyone is happy about invoking Einstein’s anti-gravity to explain the accelerating expansion. Part of the problem is that the amount of energy in, say, a million cubic kilometres of empty space is entirely arbitrary. It is, however, an exceedingly tiny number: astronomers measure it to just enough energy to boil a kettle if it could be harnessed. But why that particular number and not some other?

Appeals to quantum physics to derive a value for dark energy fail spectacularly. One estimate is out by about 120 powers of ten! Maybe space is permeated by a new sort of field that produces just the right amount of cosmic repulsion, but so far all we have to show is a lot of different models and calculations and nothing definitive.

The question “What is dark energy?” is high on the list of outstanding problems in fundamental science.

https://cosmosmagazine.com/science/physics/what-cosmological-mysteries-are-left-for-physics-to-solve/

 

[CaaC (John)+]

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The mysteries of ultradiffuse galaxies

Simulations show they have a range of bizarre origins.

An international team of astronomers have shed light on a mysterious galactic phenomenon: elusive ultradiffuse galaxies.

Ultradiffuse galaxies (UDGs) are dwarf galaxies whose stars are spread out over a vast region, resulting in extremely low surface brightness, making them very difficult to detect.

An international team of astronomers have used simulations to detect a few “quenched” UDGs – ones that don’t form stars – in low-density environments in the universe.

Their report is published in Nature Astronomy.

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Read more: Galaxies expel murkier gas than they take in

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“What we have detected is at odds with theories of galaxy formation since quenched dwarfs are required to be in clusters or group environments in order to get their gas removed and stop forming stars,” says Laura Sales, a researcher at the University of California, US, and co-author on the paper.

The quenched UDGs the team detected are not clusters – they’re isolated. The researchers were able to trace their evolution backward in time to show they originated in “backsplash orbits” – an object that looks like an isolated galaxy today but in the past was a satellite of a more massive system.

 

“Isolated galaxies and satellite galaxies have different properties because the physics of their evolution is quite different,” Sales says. “These backsplash galaxies are intriguing because they share properties with the population of satellites in the system to which they once belonged, but today they are observed to be isolated from the system.”

A UDG has the stellar content of a dwarf galaxy: 10–100 times fewer stars than the Milky Way. But its size is comparable to the Milky Way, giving it the extremely low surface brightness that makes it special.

Sales explains that the dark matter halo of a dwarf galaxy has a mass at least 10 times smaller than the Milky Way, and the size scales similarly. UDGs, however, break this rule and show a radial extension comparable to that of much larger galaxies.

“One of the popular theories to explain this was that UDGs are ‘failed Milky Ways,’ meaning they were destined to be galaxies like our own Milky Way but somehow failed to form stars,” says José A Benavides, a graduate student at the Institute of Theoretical and Experimental Astronomy, Argentina, and the first author of the research paper. “We now know that this scenario cannot explain all UDGs. So theoretical models are arising where more than one formation mechanism may be able to form these ultradiffuse objects.”

According to Sales, the value of the new work is twofold. First, the simulation used by the researchers, called TNG50, successfully predicted UDGs with characteristics similar to real observations. Second, the researchers found a few rare quenched UDGs for which they have no formation mechanism.

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Read more: Could Dyson spheres around black holes power alien civilisations?

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“Using TNG50 as a ‘time machine’ to see how the UDGs got to where they are, we found these objects were satellites several billion years before but got expelled into a very elliptical orbit and look isolated today,” she says.

The researchers also report that according to their simulations, quenched UDGs can commonly make up 25% of an ultradiffuse population of galaxies. In observations, however, this percentage is much smaller.

“This means a lot of dwarf galaxies lurking in the dark may have remained undetected to our telescopes,” Sales says. “We hope our results will inspire new strategies for surveying the low-luminosity universe, which would allow for a complete census of this population of dwarf galaxies.”

https://cosmosmagazine.com/space/astronomy/the-mysteries-of-ultradiffuse-galaxies/

 

[Bluewolf]

Just my yearly reminder that the moon landings might seem a bit iffy when presented with real facts... 

What was your favourite gif? This is mine. - 9GAG

[nudge]

23 minutes ago, Bluewolf said:

Just my yearly reminder that the moon landings might seem a bit iffy when presented with real facts... 

What was your favourite gif? This is mine. - 9GAG

Explains all the craters...

[CaaC (John)+]

Edited September 14, 2021 by CaaC (John)

[CaaC (John)+]

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Move over Dr Who: We can travel the (virtual) universe too

Seeking adventures in space and time from the comfort of your couch?  Step aside Dr Who. The entire known universe is at our  fingertips.

An international team of researchers has generated an entire virtual universe and uploaded it to the “cloud”. They then made it freely available to anyone who wants to explore the cosmos without the pesky laws of physics (and economics) getting in their way.

Uchuu (meaning “outer space” in Japanese) is the largest and most realistic simulation of the universe to date. It consists of 2.1 trillion particles in a computational cube that’s an unprecedented 9.63 billion light-years across – about three-quarters of the distance between Earth and the most distant observable galaxies. The simulation was unveiled in a study in Monthly Notices of the Royal Astronomical Society.

Uchuu is a virtual copy of the large-scale structure of the universe. It even contains the mysterious haloes of dark matter that control the formation of galaxies and the fate of the universe itself.      

It doesn’t re-generate individual planets and stars, however.

The team of researchers, from Japan, Spain, the US, Argentina, Australia, Chile, France and Italy created Uchuu using ATERUI II, the world’s most powerful supercomputer dedicated to astronomy. But even with ATERUI II’s epic computational power, the simulated universe took a year to generate.

Tomoaki Ishiyama, an associate professor at Chiba University who developed the code used to generate Uchuu, explains: “To produce Uchuu we have used … all 40,200 processors (CPU cores) available exclusively for 48 hours each month. Twenty million supercomputer hours were consumed, and 3 Petabytes of data were generated, the equivalent of 894,784,853 pictures from a 12-megapixel cell phone.”

To circumvent the problem of download time, the team used high-performance computational techniques to compress the information on the formation and evolution of dark matter haloes into a 100-terabyte catalogue. This catalogue is now available to everyone on the cloud in an easy-to-use format thanks to the computational infrastructure skun6 located at the Instituto de Astrofísica de Andalucía (IAA-CSIC), the RedIRIS group, and the Galician Supercomputing Center (CESGA). Future data releases will include catalogues of virtual galaxies and gravitational lensing maps.

It’s not just a flight of fancy. Uchuu will help astronomers learn how to interpret big data galaxy surveys from facilities like the Subaru Telescope and the ESA Euclid space mission.

Uchuu also has a time dimension; it simulates the evolution of matter over the entire 13.8-billion-year history of the universe. This makes it a powerful tool for understanding how the universe came to be, and how it may evolve into the future.

Julia F. Ereza, a PhD student at IAA-CSIC, explains the importance of the time domain: “Uchuu is like a time machine: we can go forward, backward and stop in time, we can ”zoom in” on a single galaxy or ”zoom out” to visualize a whole cluster, we can see what is really happening at every instant and in every place of the universe from its earliest days to the present, being an essential tool to study the cosmos.”

https://cosmosmagazine.com/space/astrophysics/move-over-dr-who-we-can-travel-the-virtual-universe-too/

 

Edited September 14, 2021 by CaaC (John)
Spacing correction

[nudge]

Jupiter is very bright tonight, and in conjunction with Moon (4 degrees). Looks amazing. I just observed that and the Perseids, great night for stargazing.

[CaaC (John)+]

3 hours ago, nudge said:

Jupiter is very bright tonight, and in conjunction with Moon (4 degrees). Looks amazing. I just observed that and the Perseids, great night for stargazing.

Every time I get up early and look out the window all I see is nowt becuase of visibility (clouds) and it's frustrating as hell, this is what is above me now that I can't bloody see...