Sunday, 19 April 2015

Searching for a galactic empire?

 
In search of Galactic Empires

When people look for evidence of an alien intelligence at work they're usually looking for something like Earth,  maybe a bit more advanced, maybe a lot more and spread across several worlds or even several star systems. What no one,  as far as I know,  has looked for before is an alien supercivilisation- a civilisation that controls a whole galaxy.

Until now.

Above: Why absorb the power of a whole galaxy? I refer you to Emporor Palpatine in the last moments of this clip for the answer. Courtesy of ... erm.... Disney?




This might sound like the brain child of someone who has been watching too many Star Trek episodes, or who has the Star Wars theme tune playing on a loop in the back of their mind all the time (it's not me, I promise). But it's actually from a team of serious astronomers who've set up a low key scheme called Glimpsing Heat from Alien Technologies (G-HAT). And there is a logic behind this: If you calculate how long it would take to set up a galactic empire... well it's looong in human terms. But compared to the life of most stars, or galaxies, or the universe itself, it's a short span of time (a few million years or so for a really determined race).

True, lots of races might not be interested in that kind of aggressive expansion, lots might be too primitive, might be too energy efficient, or might take steps to conceal themselves from whatever the interstellar equivalent of boogymen are. But if even a handful decided to go the route of 'colonise and dominate' across a whole galaxy we should be able to spot them.
To go into a bit more depth here's a talk (erm, well, a  full hour long lecture) on why that is from the big brains at Oxford University:

 
Above:This is really worth the time to watch - robot butlers lead to destroying the planet Mercury, and then conquering the whole galaxy. With gigantic rail guns. Seriously, Bond villains have nothing on real world physicists. And we could start doing this today.

The reason why we think we should detect any super civilisations is that there's a law of physics that says any energy using machine will give out heat (it's called the 2nd law of thermodynamics). Assuming that we're right about this law, and as far as we can tell we are, a civilisation spanning a whole galaxy should put out a lot of heat. What's more, such a civilisation would probably use the most obvious sources of power to power their empire ; their galaxies stars themselves, so they'd probably be collecting a significant fraction of their galaxies star light with solar panels - and eventually that energy would get re-radiated as heat too. By the way, the term for covering a sun in collectors to absorb all it's power is 'Dyson structure' or 'Dyson sphere' - it's industrilisation gone insanely large scale.


Above: Fraser Cain, editor of Universe Today websoite, gives us a quicker run down on what a Dyson sphere is. 

And, yes, they turn up in Star Trek:

 
Above: The starship Enterprise encounters a Dyson Sphere. Later on they find Scotty trapped in a transporter beam, and a technobabble off between him and Geordi Laforge results in a deadly spacetime rip.
Honest.
The overall effect would be to make the whole galaxy dimmer in the visible light frequencies, and brighter in the infra red, and this is something that the the WISE space telescope might be able to pick up - so GHAT has been combing through its data, looking for any suspect object that might fit the description.

The GHAT team have found a hundred thousand galaxies that definitely aren't heavily modified in this way. That has left just 50 that might - and only might as a theoretical possibility - be evidence of an alien super civilisation using between 50% and 85% of their galactic energy output, and ultimately re-radiating it as heat. Several of these objects are newly discovered, and in the team recommend that they be followed up by investigations from both SETI and more conventional astrophysics, because they look interesting even if they're not signs of super space aliens.

Elsewhere in the universe:

Ceres:
Another bit of Ceres related coolness from the image processing gurus at unmannedspaceflight.com:


This back and forth rocking animation of Ceres north pole was put together by the talented Toma B, and helps us to pick out surface details a bit more easily.

Procyon probe has a target (with a Moon) selected: The Procyon probe isn't about space exploration as much as how small a working interplanetary craft can be: It's barely bigger than a big pillow, and is testing an experimental, super lightweight, ion drive and thruster system.

Above: One of the probes experimental, ultra small, thrusters. Courtesy of JAXA
The probes only sensor is a telescope, and when it was launched it didn't even have a destination.... but now it does! It's going to an asteroid called 2000  DP107, which was the first asteroid ever discovered to have it's own moon.
Above: The Procyon micro satellite - one edge is about as long as a larg-ish laptop. If it hadn't gone into space it would have made a very interesting table ornament - it'd be a conversation starter, especially when you mentioned what it cost.... Courtesy of JAXA

Elsewhere on the internet:

Edge of space balloon to explore how cosmic rays damage computers

New dark matter hunter starts this autumn

Dark matter mapped by cosmic shear

New Horizons gets first colour snaps of Pluto 

The Batman Vs Superman trailer is out:


Latest Star Wars trailer is out:




Thursday, 16 April 2015

Dawn space probe gets an eyefull of Ceres' north pole

Just a quick note: The Dawn space probe has emerged from the shadow of Ceres, and started sending back images. The first are some beautifull shots of the dwarf planet's north pole:


The mysterious bright spots aren't in view yet, so all us space geeks are going to have to wait a while longer for the next batch of clues to what they are....

Above: Still no idea. Possibly it's graffiti? Courtesy of NASA
Elsewhere on the internet:
Giant galaxies die from the core out
Dark matter shows signs of interacting with itself
Prebiotic molecules found near young sunlike stars

Wednesday, 15 April 2015

How to make water on Mars....


The idea that there might be water on Mars has been beguiling and fascinating us for decades. Why? Because, on Earth at least, water means life - and the idea of finding life on another planet fascinates us. It's been known for a while that Mars had plentiful water, even an ocean, billions of years ago.......

Above: NASA explains about the Martian ocean. They do a few cool things like this, have alook around youtube for them!

......and even in later epochs volcanoes would occasionally melt surface ice. But this week some new analysis of the Martian desert (here's the abstract in nature), drawing on both data from the Mars rover Curiosity and the fleet of orbiting space probes, has made it seem that much more likely there is some liquid water still on Mars today (link here).

What has been discovered is a natural antifreeze, called calcium perchlorate, in the soil at Curiosity's location. As well as being an antifreeze calcium perchlorate absorbs moistuire out of the surrounding environment, and when it has absorbed enough a perchlorate particle turns into a droplet of perchlorate saturated water. Here's a video of the process, which is called deliquescence, turning a tiny crystal of regular salt into a droplet under a microscope:

Above: No, that isn't an ice blockmelting, it's a tiny crystal of table salt absorbing enough water to become a droplet of hypersaline water.


On Earth hypersaline (very,very salty) water forms pools that stay liquid even down to -50 degrees celcius. On Mars the ability to stay liquid at low temperatures has a double benefit: It keeps the water from freezing solid, and it keeps the liquid from evaporating away in the very thin atmosphere.

The Copenhagen team haven't found any lakes, but what they have done is use curiosity to measure how much water vapour the soil is absorbing out of the thin martian air - and it seems that enough is being taken up to form these antifreeze laden drops. The soil also contains evidence of these droplets migrating through the soil and into the ground. While this isn't as promising as a direct detection of water would be, it is an interesting find, and increases the chances that areas on Mars nearer the poles, with more vapour in the atmosphere, might be able to form enough water to support hardy microbes.

Above: Don Juan pond in
Antarctica, where the salts in the water keep it liquid even at minus fifty degrees celcius. Put your fingers in and... well that'd be waste of fingers. Courtesy of the British Antarctic Survey. 

Elsewhere in the universe:

Evidence for a Martian ocean, water activity in gullies,  and subsurface lakes:
The European Geophysical Union has given a press conference , outlining three new water related lines of evidence about Mars: The first speaker gives more evidence supporting the idea that Mars had an ocean in ancient times, the second talks about how some martian gullies may have formed by wet debris flows, and the third describes how large floods came bursting from underground resevoirs. The EGU haven't made a copy of this on embeddable yet, so here's the link.

Even more on Marian water: Martian mountain might be 'leaking':
A mountain system on Mars shows signs that rust and salt polluted water might be leaking out from underground reservoirs on a yearly basis.

Above: The redder streaks running down this mountain might be formed by rust polluted water running down the flanks until it evaporates. Or not. If it is, and you're reading this from Mars near that mountain (anything is possible), don't drink the stuff. Courtesy of HiRiSE

SpaceX successfully launches supplies and experiments to the space station, but just misses re-usability goal:
Elon Musks SpaceX company has successfully launched one of their Dragon spacecraft to the international space station, with a cargo of supplies and experiments. The company came close to landing the rockets first stage on its ocean barge/landing pad,  but it toppled over and broke into pieces moments after touchdown.


Above: Ooooh.... that was so close! The rocket actually lands safely on the pad,but just after this finishes it fell over! I'll take the glass half full point of view - this bodes really well for the next try! Courtesy of SpaceX.

Vulcan rockets to launch in 2019, will try a different take on re-usability
The ULA designed Vulcan rockets will parachute their engines back to Earth. Facing ever stiffer competition,  and demand for lower prices, United Launch Alliance is hoping its innovative design wil help it keep its competative edge.

Monday, 13 April 2015

Opinion: Apollo 13 to today - how far have we come?




Apollo 13 to today - how far have we come?

This Monday is the 45th anniversary of the Apollo 13 mission. In case you don't know what happened - it was 45 years ago, c`mon, some people seriously won't have - it was a crewed spaceship, on an exploration mission to the Moon.One of the crew called mission control and said "We've had a problem". Now, this was at a time when space travel was solely for the bad assest of the bad assest, so the problem was that... um well check out this re-enactment from the (historically very accurate)movie with Tom Hanks :

Above: Tom Hanks tries to explain to his space ship that now wasn't a great time to do terrible thing it just did. Courtesy of movieclips.com

Hollywood does exaggerate things though, doesn't it? Well, in cased you're wondering just how Hollywood that was, here's a photo taken by the crew of how banged up their ship really was :

Above: The top picture is how Apollo 13 looked as the crew abandoned it (well, the service module part at least). The bottom is how it should have looked. Courtesy of NASA

..and to get it from the horses mouth, here's commander Jim Lovell and his crew, speaking at a press conference not long after they made it home:



How far have we come since then? 
Something I hear a lot amongst space advocates is that, with hindsight, Apollo 13 represents a double failure: Not only was the mission a failure that almost killed the crew, but the Apollo missions themselves are a bitter example of how much mankind can achieve in space....... but doesn't. After all, it's been over forty years since humans went beyond Earth orbit.

Above: The Launch of Apollo 17, the last time that humans went into deep space in person. Courtesy of Dan Beaumont film.
This is a point of view held by some very clever people, who were actually involved in Apollo (although by no means all of them), but I disagree:
In 1969 to 1973 we had the massive, cold-war-inspired, effort of Apollo. Riding a budget that was many times bigger than today's (in real terms), with unwavering political support, NASA accomplished the seemingly impossible: It landed people on the Moon:

Above: If I need to tell you what this is then shame on you. Unless you're like five, in which case: It's the first spaceship to land on the Moon. And well done for getting onto my website. Does Mum know you're using her computer..?

But there was no surface exploration of other planets. None of the smart machines we have flying about our solar system today - there were automated probes to other planets but they were crude, simple, and so rare. Indeed, any and every space launch was a major event. No space stations. No reusable spacecraft. The very idea of a private company looking to access space, or build their own ships would have been laughable. Now, for kicks, check out the timeline of space exploration over on Space.com (Link here)

Above: The Millennium Falcon isn't on that timeline. Yet. I have plans....

Look at how many firsts, both exploration, technological (and even in human spaceflight) come after Apollo ended. The end of the Apollo era budgets may have quashed many of the big dreams, but it forced space exploration into an era of innovation it might otherwise have missed. And, thanks to the missions that have flown since Apollo, we have views like this...

Above: Saturn, seen with the Sun behind it, by the Cassini space probe. Courtesy of NASA

...and this....
 


Above: Sunset on Mars,as seen by the Curiosity rover. Courtesy of NASA.
...and this....


Above: A video taken by the MESSENGER probe as it swoops low over the surface of Mercury. Courtesy of NASA.

...and this....
Above: the plumes of Enceladus, where an mysterious heat source is powering geysers and an underground ocean on a small moon of Saturn. Courtesy of NASA.

...available to the whole world. We know that Mars once was a habitable world, and we're on the way to hunting down the best place to look for any life that was there. We've discovered that worlds like Europa, and Enceladus have oceans to explore, that comets carry the chemical building blocks of life, and that Saturn's moon Titan is a very, very weird place that we can learn a lot from. This year we begin exploring Pluto and the Kuiper belt, and the Dawn mission will map the dwarf planets for us.

And as for manned exploration? It's true, we haven't gone beyond Earths protective magnetic field since Apollo. But today space launches to thew biggest, most sophisticated space station ever built, are routine. Even manned flights are a normal thing.


Above: A tour of the International Space Station, the biggest, most sophisticated space laboratory ever built. Courtesy of NASA/ESA.

We have innovative new approaches to space, like the rise of miniaturised space craft: Cubesats and chipsats are opening space to more and more ordinary people. We have the burgeoning space tourism market. We have many, many missions like Hubble, which stay in earth orbit but look out to the stars -  and have discovered alien solar systems, and imaged planets around other stars. That was feat many scientist though would be impossible for centuries in 1970. And all of the above barely begins on all the missions and discoveries we've made.

Would I love to see ts on Mars, a lunar base, or a manned Jupiter mission? Hell yes. It's a crying shame that space exploration doesn't receive the same high priority treatment that Apollo did, all across the world. But can we really say we've not done anything great since Apollo, that what the crew of Apollo 13 risked their lives for (and other crews died for) has never come to pass?

I suggest this: Go to the timeline of space exploration I linked earlier. Put a few of the missions there into Google, read about the discoveries, and the future plans. I think you'll see: We've come a long way since Apollo 13.

Elsewhere in the Universe:

Conditions for liquid water to form exist at Curiosity rover landing site:
A team from Copenhagen have looked through the data returned by the mars rover Curiosity, and found that the conditions for liquid water to form exist there. A form of perchlorate salt in the soil is able, under the right atmospheric conditions, to suck moisture out of the air until it becomes droplet of salty water. Even a tiny amuont of confirmed liquid water on Mars raises the chances of some form of live clinging on there, and this makes it seem all the more likely.

25th anniversary of the the Pegasus rocket:
The Pegasus is a unique launcher, because it is carried above the lowest, thickest layers of atmosphere by an airplane before launching:


Above: Pegasus launches the IRIS  satellite.
 
Similar systems, involving jet fighters, are being planned by both private companies and by the DARPA  agency. This week is the 25th anniversary of the pegasus system, showing that such a launcher has the commercial staying power needed to succeed.

Elsewhere on the internet:
Titan storms explain giant dunes
Colour map of CERES reveals an active world

Friday, 10 April 2015

The MESSENGER nears the end of the journey - but what’s that in the shadows?


The MESSENGER mission to Mercury is winding down. The navigation thrusters are exhausted, and the team have directed their probe to make series of ultra low altitude passes over the surface, so that they can make the most use of the magnetometer and the neutron spectrometer (which measure the magnetic field and the surface composition respectively). They're already getting pretty low over the surface, but now they'll come within a few kilometres of Mercury's rocks and take videos like this:

Above: This video was taken by the MESSENGER  spacecraft as it flew low over Mercury - keep your eyes open, there are some of the surface features mentioned in tHis post wizzing past the camera! Courtesy of NASA
This will be the final phase of the mission - but fascinating things about Mercury are still emerging. They will keep doing so for years I expect - it needs a lot of time to sift through the mountains of data a space probe collects, and find that thar gud stuff. But at the 46th Lunar and Planetary Science Conference this year there were two tantalising mercury findings from MESSENGER, both pointing to alien geological processes at work:

Something hidden in the eternal night:

Above: Permanently shadowed craters at the poles of Mercury. Yes, I know they're all red and yellow, that's just the graphics. Courtesy of NASA
Mercury, like our Moon, has permanent regions of darkness near the poles, and these have a layer of reflective water ice coating their floors. That ice might have come from comet impacts, or might have been caused by the rocks of Mercury chemically interacting with the solar wind. Although it's weird that a world so near the Sun would have lots of ice, it makes sense because Mercury has no atmosphere to level out its temperatures. So, although the surface of Mercury is oven-hot in the sunlight, in the shadowed regions it's incredibly cold - cold enough for the ice to accumulate and be stable.

Above: Colder than that. Colder than that if you had to spend the night at the bottom of those stairs. After your wife caught you spending the kid's college fund on beer and Doritos. Courtesy of NASA.
That's a big deal in itself, but the story takes a twist when we look at craters and valleys that are a bit further from the poles, and just a touch too warm to let ice be stable over the long term. Here MESSENGER doesn't see a layer of reflective water ice. Instead it sees craters filled with a layer of .....something. Something very dark.


Above: Something even darker than the lyrics of black metal band Marduk. And, in case the outfits and the genre weren't a clue, they write... well, not nursery rhymes. At least I hope none of you are playing your kids Marduk as nursery rhymes. Mind you, have you ever read the originals of fairy stories? Courtesy of MusicTimes
Black materials are common in the solar system, but what's strange here is this: Over Mercury’s lifespan the relentless bombardment of meteorite impacts should have blurred and smeared the boundaries of any patch of material on the surface, but the edges of the black layer are almost razor sharp. It could just be one of those odd coincidences that this stuff formed just as MESSENGER arrived, but it seems more likely that the edges are somehow being repaired.

Self repairing black masses, hiding in the bottom of permanently shadowed craters, on a sun drenched planet -  now that's the kind of alien phenomena we go into space to discover.

Other sensors carried by MESSENGER, like the radar sounding experiment, suggest that there’s a layer of water ice beneath the black material, so the leading theory is that the ice in the craters has some kind of organic material mixed in with it. As ice in these these craters isn't stable over the long term the ice gradually evaporates, leaving behind a layer of organic chemicals on the surface. The layer then protects and preserves the remaining ice. If the layer is breached then the newly exposed ice repeats the processes. These organic materials could even contain compounds related to the origin of life, as similar deposits on the moon are thought to.

But right now this is just our best guess - this might be possible if the ice was mainly due to accumulated comets strikes, as they’re rich in both ice and organics. But if the water molecules are formed chemically from solar wind and the rocks it’s harder to see where the organics could be coming from.

Different flavours of hollows:

Above: These weird hollows seem to be caused by something undermining the top layer of rock and soil, and are growing all over the planet (BTW, this is a very exaggerated colour image, to bring out the details). I'm not saying it's Mercurian mole people. That'd be crazy, and besides they might have agents here on Earth who'd undermine my house if I gave them away... Image courtesy of NASA.
These weird looking holes in the Mercury's crust have been  showing up in MESSENGER images since the probe arrived: They’re areas of ground that have been eroded away in a mould-like pattern by some unknown process, all to roughly the same depth, all across the planet. Crater counting shows them to be geologically young, and probably forming still today. But exactly what process has created them… it’s a mystery.
One idea is that there are stores of volatiles below the surface, and that, as these evaporate beneath the blazing Sun, they cause the ground to collapse. But again, we're into 'best scientific guess' land here. To thicken the plot: At LPSC some of the UV spectrometer results from MESSENGER were revealed, showing that some of the hollows have different surface compositions – this might represent inherent differences, or it might be that some of the craters are older and space weathering has changed their surfaces.

Mercury has turned out to be far from a dead chunk of rock  -  the above are just a couple of the mysteries we've found there. Wouldn't it be great if there was a follow up mission being developed? well there is, it's called Bepicolumbo!


Above: A quick rundown on the upcoming Bepicolumbo mission, courtesy of ESA.

Elsewhere in the universe:
Above: A depiction of the Methyl Cyanide molecule. The 'H's are hydrogen atoms, the 'C''s are carbons, and the N is a nitrogen

Molecules implicated in the origins of life have been spotted in a still forming solar system. The Methyl cyanide molecule, and its simpler sibling hydrogen cyanide, are thought to be amongst the ground level molecules for the chemical evolution that leads to life, so their detection suggests that they’re present in a lot of young planetary systems – great news for alien hunters as it raises the possibilities of finding worlds with the chemistry needed for life. This isn’t the first time complex , life related molecules have been found – sugars have been found, amino acids have been shown to form on interstellar dust, and tar like compounds have been found in distant reaches of the universe. But this is the first time molecules so directly life related have been found in a growing solar system – not too dissimilar to the way our own is thought to have been 4.5 billion years ago.

SpaceX is going to make another attempt to land and re-use it's Falcon 9R rocket. their last attempt came close but...well here's the video:

Above: Owch. But, I should point out, SpaceX shared this video themselves - that's how sure they are they know what went wrong and can get it right.

Lastly, this is pure science fiction, but it's awseome. And it's being made into a movie!


Elsewhere on the internet:

Monday, 6 April 2015

Mission into the inferno

Happy Easter everyone!

  Above: I have a stomach bug, and I look hanging so I'm not showing my face - but I'll show you how I track sunspots and solar facula* instead.
Mission into the inferno:

For most of our history mankind has been wondering what the big bright thing in the sky actually is.

No. No, it's not a big torch.Why would it be up there? It belongs in someones garage. I'm talking about the Sun you loonies.




Now we have telescopes, spaceships, and supercomputers, and we're finding out that the big bright Sun is a star, and it has all kinds of weird and wonderful features. In fact, the more we observe the Sun in detail the more of a complex and astounding place it becomes. For example: In 2013 the University of Central Lancashire launched a set of experimental optics into space on a sounding rocket about a year ago, to observe the UV Sun with five times the detail ever seen before. What they found (link here) was astounding:

"....small clumps of electrified gas (plasma) at a temperature of about one million degrees Celsius are seen racing along highways shaped by the Sun's magnetic field. These blobs travel at around 80 km per second (the equivalent of 235 times the speed of sound on Earth), fast enough to travel the distance from Glasgow to London in 7 seconds. The highways are 450 km across, roughly the length of Ireland from north to south.... ....Astronomers have long struggled to understand why, with a temperature of two million degrees, the corona is around 400 times hotter than the solar surface. Hi-C images reveal dynamic bright dots which switch on and off at high speed. These 'sparkles' typically last around 25 seconds, are about 680 km across (the size of the UK) and release at least one million million million million Joules of energy in each event or around 10,000 times the annual energy consumption of the population of the UK (based on information from the UK Department of Energy and Climate Change). The sparkles are thus a clear signal that enormous amounts of energy are being added into the corona and may then be released violently to heat the plasma"

Above: A video made from the images collected by the UClan mission. Courtesy of University of Central Lancashire.

Partly because of the complexities and mysteries of the Sun, and partly because most scientists and engineers view the story of Icarus as a challenge rather than a warning, a space mission is under development that will fly a robot space probe into the Sun's atmosphere. Launching in 2018, this will be extreme engineering at its most extreme: Over six years Solar Probe Plus will perform six slingshots of the planet Venus, to change its course and velocity. Then, as it falls past Mercury under the Sun's immense gravity, the probe will reach speeds of over 200 km per second.


Above: A CGI image of the completed probe, leaving Earth orbit. The solar panels are stowed away, behind the heat shield, and frankly the whole thing looks like it's flying backwards to me, but then it's not built for looks it's built to nosedive the Sun and get away with it. Image courtesy of NASA
The Sun will be a wall of light and heat, filling its sky, so the probes heatshield will be one of the most heatproof things ever built: A carbon-carbon carbon foam barrier 4 inches thick and weighing 1,350 lb. Sat in the shield's shadow, the probe will draw power from the torrent of light around it using solar panels - but normal panels would fry in the heat, so these will need to be cooled. But the heat isn't the only problem: High speed particles and dust, driven by the immense magnetic fields, will be just as much of a danger.

What mysteries would make it worth sending a multi-million dollar robot into such a furnace? Here are a few of them:

How does the solar wind begin?
The solar wind is a high speed stream of plasma sent out by the Sun. When it gets choppy we get solar storms, radiation spikes, aurora..... and damaged to satellites, and even to power grids here on Earth. But we understand very little about how the solar gets its speed and power.



Above: The tenous gas of the solar wind can wreak surprising havoc when it gets mad....

How complex is the structure of the magnetic field near the Sun's surface?
Everything about the Sun involves its immense magnetism in some way, and mapping the magnetic fields in detail will help us understand how our star works. Flares, prominences, storms, sunspots - they all grow out of the Sun's twisted and gnarled magnetic field.


Above: NASA gives a quick explanation of how the Sun is about to do something really strange...

What role does 'complex plasma' (ionised gas mixed with electrically charged dust) play in the mechanisms of the suns surface? 
Complex plasmas are known to behave in incredibly rich and complex ways - it can act like a crystal, a fluid, a vortex, or a flow. It can change the way magnetic and electric field propagate and have even been theorised to host patterns that are a deep space analogue to DNA.

For a bit more information - and by that I mean a lot more information - make a cup of tea or coffee and sit down to watch SETI's Stuart Bale give a talk on the mission:



Elsewhere in the Univerese:
For a long time people have wondered about colonising the Moon, but the harsh lunar surface - temperature swings of hundreds of degrees, micrometeorites, the full blast of solar storms, other kinds of radiation like cosmic rays - makes a tough challenge. To get around this it's been proposed that colonists might build their homes in the lava tubes - tunnels through the rock which lava flowed along in the ancient past:



Above: Lava breaking out of a lava tube and onto the surface. Courtesy of 
 
Now a theoretical study from Purdue University suggests that these tunnels might be  up to 5 kilometres across . Easily big enough to hold a city. The key to their immense size would be a combination of low low lunar gravity and the naturally strong arches lava tubes form.

Elsewhere on the internet:

Young star develops visibly over 18 years

White dwarf to blame for supernova

Black holes don't destroy information

Dark matter doesn't even 'see' itself.

* This is not a rude word, it's a brighter spot on the Sun. Shame on you...... and me, since I must've thought that too.

Wednesday, 1 April 2015

Can clouds of atoms pin down dark energy?

Dark energy: It's one of cosmology's big mysteries. It also proves that scientists can  do a cool name if they try - it sounds sexy as hell and it's been name checked in all the cool sci-fi movies. But we don't have a clue what it actually is.

Above: In the Marvel movie universe it's embodied by this big glowing dice. Real world cosmologists would find that much more convenient to study I suspect...



While the nature of dark energy isn't a matter of immediate panic it is a source of long term worry, as it's  tearing the universe apart - if it keeps accelerating the expansion of space all the other galaxies will eventually disappear at faster than light speeds*. It's slightly embarrassing to be facing  the end of creation as we know it without a clue as to why, so it's something we'd like to get a handle on. For a slightly less melodramatic explanation here's the big brains at Imperial College (warning, this is a full blown physics lecture, so put a cup of tea/coffee on):


One of the suspects in our man hunt is called  a 'chameleon field'. The chameleon field would be a kind of dark energy that is suppressed by matter (or large concentrations of energy) very well. This would explain some of the stranger aspects of dark energy, like why it seems to be very, very, powerful over very long distances, but can't be measured on Earth. On Earth all the dense matter suppresses it.

Above: Earth. Beautiful and, apparently, inconvenient for dark energy hunters. Courtesy of NASA

But Clare Burrage, Edmund J. Copelanda, and E. A. Hinds at the University of Nottingham have come up with an experiment that, maybe, could measure the dark energy field - if it is the chameleon type. The experiment would consist of a big vacuum chamber containing as much nothing as possible - since the chameleon field is suppressed by matter and energy an empty vessel  is the best chance of bringing it up to detectable levels. A stream of cooled rubidium atoms would be fired through the chamber, while it was weightless. Any unexplained deflection of the atoms could be evidence of the chameleon force. This sort of approach is already used to measure fundamental constants like gravity, so the team has been able to put some upper limits on how big the chameleon field might be. Here's the paper. I'll be interested to see if anything comes of it...

Elsewhere in the universe:

Galaxies in this universe cluster together like... like... well, like galaxies clustering. Things that huge can't really be like much except themselves. But how did galaxy clusters begin? The Herschel and Plank space telescopes have teamed up to look waaaay back in time and find the answer.

Above: The image in the centre is the Plank all sky map, and the little images are the Herschel images of possible galaxy cluster seeds. Courtesy of ESA.

Elsewhere on the internet:

Scuttling_satellites_to_save_space

Suck on this Tatooine

Mapping cosmic rays

An attempt to make robots conscious?

Graphene sandwich produces new form of ice

Radio bursts - alien messages?


*Yes that sounds crazy. Yes it's true: The rules let you do faster than light if space is the thing that's moving rather than you.