Sunday, 29 March 2015

The 'WOW' signals - are they real?




 

The 'WOW' signal - did S.E.T.I find something?

If, like me, you have 'space nerd' written through your middle then you can probably skip straight to the Carl Sagan quote. If not...

Have you ever heard of S.E.T.I ? It stands for 'Search for Extra Terrestrial Intelligence', a group of scientists who search the sky for any signals that might be created by an alien civilisation. After all, we've made our planet Earth LOUD on almost every frequency so why wouldn't at least some alien worlds (if they are out there) be the same?

Above: The view from the International Space Station of the lights of Earth - that much power being put out might be detectable to someone....
It's the stuff of space geek legend* that, once, the S.E.T.I project did pick up a signal that looked exactly like we'd expect an alien signal to look. No other explanation has ever accounted for all the quirks of it,  and no one has ever admitted to being behind any kind of hoax. But the signal never repeated, so it  was never possible to verify.
It's called the 'WOW' signal, and it's always just been one of those mysteries. To be honest, as intriguing as the idea is, I've never really thought much about it.

Above: Me, not thinking.
Then,  a couple of weeks ago I stumbled upon** a quote by Carl Sagan, one of the main movers behind S.E.T.I and a famous promoter of science. It's from his book Pale Blue Dot, and it's in the chapter entitled 'darkness':


"....we ignore anything that isn't much louder than the background. Any strong narrow-band signal that remains in a single channel we take very seriously. As it logs in the data, META automatically tells the human operators to pay attention to certain signals. Over five years we made some 60 trillion observations at various frequencies, while examining the entire accessible sky. A few dozen signals survive the culling. These are subjected to further scrutiny, and almost all of them are rejected-for example, because an error has been found by fault-detection microprocessors that examine the signal-detection microprocessors.

What's left-the strongest candidate signals after three surveys of the sky-are 11 "events." They satisfy all but one of our criteria for a genuine alien signal. But the one failed criterion is supremely important: Verifiability. We've never been able to find any of them again. We look back at that part of the sky three minutes later and there's nothing there.....
just possibly, this is the effect of twinkling. Stars twinkle because parcels
of turbulent air are moving across the line of sight between the star and us. Sometimes these air parcels act as a lens and cause the light rays from a given star to converge a little, making it momentarily brighter. Similarly, astronomical radio sources may also twinkle-owing to clouds of electrically charged (or "ionized") gas in the great near-vacuum between the stars. We observe this routinely with pulsars.

Imagine a radio signal that's a little below the strength that we could otherwise detect on Earth. Occasionally the signal will by chance be temporarily focused, amplified, and brought within the detectability range of our radio telescopes. The interesting thing is that the lifetimes of such brightening, predicted from the physics of the interstellar gas, are a few minutes-and the chance of reacquiring the signal is small.


...Despite the fact that none of these signals repeats, there's an additional fact about them that, every time I think about it, sends a chill down my spine: 8 of the 11 best candidate signals lie in or near the plane of the Milky Way Galaxy. The five strongest are in the constellations Cassiopeia, Monoceros, Hydra, and two in Sagittarius-in the approximate direction of the centre of the Galaxy. The Milky Way is a flat, wheel-like collection of gas and dust and stars. Its flatness is why we see it as a band of diffuse light across the night sky. That's where almost all the stars in our galaxy are. If our candidate signals really were radio interference from Earth or some undetected glitch in the detection electronics, we shouldn't see them preferentially when we're pointing at the Milky Way."

A bit more digging turned up the official paper based on the results, which is here.

So, eleven signals. Does this mean there are alien civilisations out there, and scientists are just being over cautious?

Above: Yes they might be evil. We're not ruling out the idea that they might be evil, just hoping for the best here... Courtesy of LucasArts, or possibly Disney. 
Well...... no, I'm afraid not. Even if we discovered a repeating version of one of the S.E.T.I signals, it could still be down to an undiscovered natural phenomena -  when pulsars were first discovered the regularity of their signals seemed to point to an artificial origin. So much so the original code name for these star-corpses was 'LGM' - Little Green Men. It would take years of studying to be sure a signal was actually from another civilisation, and no signal has ever stuck around for long.

Above: The signals made by Pulsars, which turned out to be even weirder than aliens.... Courtesy of luisjimnez92
Um... well, almost none. 

There was one - one that doesn't make a lot of sense.In 2003 S.E.T.I picked up 'radio source SHGb02+14a'***. The group had been running the S.E.T.I @ home project, which got thousands of volunteers to use their PC time to help process the trillions of observations S.E.T.I has made. SHGb02+14a, a weak but significant radio signal, was observed three times with the help of the software. Oddly, it seemed to be coming from an empty part of the galaxy. The spot was located between the constellations of Pisces and Aries, and there's no sign of any habitable worlds in the area. The way the frequency of the signal shifted suggested its source was rotating 40 times faster than Earth - again very odd for a signal coming from a habitable planet. But, although there are other explanations, none of them has ever been confirmed, leaving SHGb02+14a as a mystery. S.E.T.I. themselves are very sceptical of the signals origin, but haven't pinned down a source

Above: A TED talk on S.E.T.I.

The story doesn't end there - S.E.T.I inspires a lot of research. The Benford family of scientists (and one sci-fi author) started thinking about the practicalities of operating a radio beacon to contact another civilisation - and their conclusion was that unless the senders already knew exactly where we are, it's pretty unlikely their signal would repeat. Like a man searching a room with a flashlight for something, their signal would only pass across us briefly. Here's their paper on how an efficiency minded ET might operate and direct their beacon, and here's another on how a pulsar might be mistaken for an alien signal. There's been even more speculation that different kinds of beacons might be used, including infra red ones, and there are a number of different observatories searching in any number of different ways.

Above: The three hundred meter big Arecibo dish. If you're going alien hunting y'all need the right tools.. Courtesy of NIAC.
What's more, searching for evidence of an alien intelligence doesn't stop at signals. Our solar system is extremely old, with enough time to have been visited by artifacts of another civilisation - in much the same way that our Voyager probes are now heading into the rest of the galaxy. Our own space exploration has left a string of artifacts - probes, landers, rovers, orbiters, statues - across most of our solar system. The GEO belt of satellites around Earth could last for hundreds of thousands of years. So there is a whole branch of the S.E.T.I effort called S.E.T.A (search for extra  terrestrial artifacts) devoted to looking for any strange objects that might be alien in origin - something I've blogged on before.

Finally, we also send our own signals - it's called M.E.T.I (messaging extra terrestrial intelligence): In 2012, on the 35th anniversary of the WOW signal, Arecibo Observatory beamed a response from humanity, containing 10,000 Twitter messages. This isn't the first time such a signal has been broadcast - Arecibo once even sent one in the direction of the Andromeda galaxy - and we've yet to receive a response. But we wouldn't be expecting one from most of the targets, not for decades if not centuries. And who knows....

Elsewhere on the internet:

Dark matter, dark energy.. now dark light?

Callisto has an atmosphere thick enough for wind, weather

Hubble searches for terrestrial planet of nearby star

How the Universe might end

Martian crater had water - twice

NASA to steal a boulder

*Or, since we know it really happened, and there're scientific papers written on it, not legend.
** By which I mean that two other people over on cosmoquestforum told me about it, but I checked it all myself.
***I've said it before and I'll keep saying it: We need to give these things better names.

Wednesday, 25 March 2015

Big stories of little planets...

The earliest days of the solar system would have been a very strange place for us -  the planets had not yet formed and instead there were hundreds of protoplanets in the inner solar system, and massive accretion cores of developing gas giants in the icy outer solar system.
Some protoplanets survived, like Ceres and Vesta, and some collided and merged over and over, until they got up to the size of full grown planets. Even in the roomier outer solar system, where there were only a few massive proto-giants, there was a lot of chaos...

Above: A simulation of what was going on in the outer regions of the protoplanetary disk. Those blobs zipping all over the place like pingping balls in a hurricane? Those are bigger than Jupiter. watch, near the end two of them smash into each other. Courtesy of 

This was a sky filled with hundreds of protoplanets, thousands of giant asteroids, millions of asteroids and comets, all filled with radioactive elements that hadn't had time to decay. Their orbits weren't that stable. And at some point it all got hit by a supernova. Possibly two, in fact.

So, when I said strange, I didn't mean 'ooh, how odd' strange. I meant strange like this guy...

Above: Hooray! I have finally managed to work a joker reference into a blog about the history of the Solar System. I can tick that off my bucket list.
We know that there were lots of head on collisions between giant asteroids and protoplanets, because today we can turn our telescopes onto young stars with protoplanetary disks and see the clouds of dust and debris blasted into space by such events.

 
Above: One of the wonders of modern space telescopes is that we can get to see just how terrifying the universe is .. but from the comfy confines of planet Earth. Courtesy of geobeats.

The irony is that the radioactivity and violence of these worlds made them, in some ways, more like Earth: All that heat meant that even tiny worlds had a geology like that of a full grown planet, with a core, a mantle, and a crust. Their molten metal cores produced magnetic fields that lasted for millions of years, not unlike Earth's. The warmth of impacts (a very explosive kind of warmth I'll grant you), and short lived radioactive nuclei, produced volcanic activity. That volcanic activity melted ice into water, and could have spewed out gas to create tenuous atmospheres.
Above: Pallasite meteorites, like this one, can contain gem quality crystals, a sign of active geology at work.Courtesy of the Natural History Museum.

It all makes for a very interesting ancient solar system - one that we'll never see, but which we can explore through the meteorites, comets, dust and debris it left behind. Which is why some new results presented at last week's Lunar and Plantar Science Conference have caught my eye:

Protoplanets may well have had liquid water for longer than thought:
It had been believed that any occurance of water on these proto-worlds would have been confined to the time when the hyperactive energy of the short lived isotopes kept everything warm. However a team from Nanjing university has challenged this, finding evidence that there was still water flowing through the subsurface of some protoplanets over a hundred million years after the radioactive heat is thought to have died out. They've found this by using a technique called uranium-lead dating* on a mineral called apatite that forms in the presence of water - in this case the apatite was found inside a meteorite, so it seems pretty likely the world this meteorite was blasted free from had running water at some point.

.. and that water moved through the rocks more easily than we thought...
There's been a lot of debate down the years about how far the underground water would have been able to move through the rocks of a protoplanet.  - it's kind of important because water that can travel a long way can mix up the protoplanets chemistry, change isotope signatures, and erode or dissolve features in the rocks themsleves. As the fragmented rocks are all we have left we need to undertsand how they were shaped. A team from MIT have done experiments showing that vapourising water can open up fractures in the rocks, allowing water to move more easily. And if you're wondering how vaporising water can break rock....


Above: Volcanic heat plus ice = BOOM. Courtesy of ITN.

Protoplanets produced right handed sugar molecules:
It's not new news that some natural process on proto-worlds was processing precursor molecules from interstellar space into sugars and other pre-biological materials. But NASA Ames researchers have done an analysis on sugars from the Murchison meteorite, and found  that these sugars  showed signs of having and excess of the right handed version of the sugar molecules. If you're not quite sure what I man by that, then check out this video:


Above: Chriality. Which is not an Armenian girl group. Although, the world being what it is, I should probably add 'yet'. Courtesy of TED.

 The NASA Ames find is definately weird, as most processes produce these molecules in equal amounts of left and right handed versions. This could be pretty important for research into how life began: It suggests that meteorites bringing organic molecules to Earth could have delivered those precursor molecules with an excess of one handedness of molecules, and so influenced which kind life preffered.

It was all born from a massive star forming complex:
A University of California team has been looking at what we know about the short lived radioactive isotopes, and concluded that it's more likely the Sun was born in a massive complex of gas and dust, which had had radiactive material pumped into it over and over by many supernova. There're are massive star forming regions like this today, such as the Vela Molecula Ridge.



Comets recycle their chemicals:

Above: Comet McNaught. that pretty green colour? that's caused by Cyanogen, which is very, very, poisonous. And you thought astronomy was a safe hobby. Courtesy of space.com
Mostly it's assumed that cometary processes are pretty much one way - bye bye, down the jet and off into space, goodbye! But, as it turns out, in the inner portion of an active comets very  extended atmosphere some molecules can be recycled. One such molecule is HCN (hydrogen cyanide) - a chemical which also has the odd distinction of simultaneously being an important precursor molecule for biological life, and an extremely deadly poison.

Impacts in the early solar system were more likely to spread life around:
Dialling the clock forwards to the early days of worlds like Earth and Mars we have a paper on lithopanspermia - the idea that microscopic life could have ridden he debris from major meteorite impacts across space to other worlds - is an idea that has sometimes struggled to get taken seriously. But, over the years, a growing body of evidence has suggested that such trips could really have taken place - something that has serious implications for the hunt for alien life, as it would meant hat any alien microbes we found elsewhere in the solar system could in fact be distant relatives of us.  Now researchers from the university of Kent have presented simulations showing that a range of microbes could survive the impact on another planet - and even one higher life form, the tardigrade - could have survived the landing on a Moon or protoplanet.

Above: The Tardigrade. This is a real life Earth creature that can survive... well, almost anything. Seriously, if they weren't so tiny they'd kick Superman and the Hulk around the room like rag dolls. CVourtesy of Eye Of science.
A lot of more main planet themed papers have made the headlines, but even a quick trawl through the abstracts shows that there was once a very different solar system, and we are slowly learning to look back in time and explore it...

Elsewhere in the universe...

Charon may be broken:
The biggest Moon of Pluto, Charon, may have tides beneath its surface strong enough to result in surface fractures -   this is based on a series of computer simulations, but it's an interesting prediction to read about as the Pluto system is about to get a visit from the New Horizons Space probe!

Jupiter wandered around the early solar system wrecking things:
The giant planet Jupiter migrated from it's original orbit, then migrated again, resulting in our oddball solar system.

Mars looks a little more promising for microbial life:
The red desert in the sky has both chemical energy sources, and the kind of nitrogen that microbes can use, making the prospects of past or present life there look a little rosier.

Robert Downey Junior gives Iron Man fan a real life bionic arm:


Elsewhere on the internet:

Pluto's moons formed from a ring of debris?
 *There's a joke about heavy metal dating to be made here, but then I'd be too ashamed to continue writing

Sunday, 22 March 2015

I'm not feeling great...

I've been feeling seriously walloped by this cold, added to a fortnight of long shifts at my day job, so I'm holding back on publishing the next Ancient Solar System entry until I can proof read it without my head feeling like it's gonna fall off - hopefully I'll be able to do the video and the rest and have it out by Tuesday. I'm really sorry about the delay, but for now I've managed to put up the Many Worlds Art entry 'Fall into the night' in its finished form which I completed during the week.....

Again, many apologies for being late, but you'd have gotten an entry that read like it'd been edited by a drunk, with a video that would've sounded like Darth Vader doing a bad voiceover on me...

Thank you How It Should Have Ended for making me feel a bit less rough...

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Friday, 20 March 2015

Darkness....

For once the side-raining, hailstoning, sunburning  Scottish weather co-operated - at first there didn't seem much hope: A path of dark blue sky mocked us and it got eerily dark.....


Then the clouds thinned a bit, and being a desperate cadre of engineers and scientists we all improvised filters and went outside. Someone more forward thinking then handed us all proper filters so we didn't end up blind...
Above: My workmates and I are grown up professionals, we didn't all come rushing outside when someone in software shouted "The clouds're thinning!". No, we're scientists and engineers, we always planned to sneak out the back door...
Above: The Scottish weather managed to combine itself with the eclipse rather dramatically....
Where we had clouds and viewing on our tea break, the Proba-2 spacecraft got the full glory:
It was strange, and beautiful! How did your eclipse go? If you've got a good eclipse story leave it in the comments section!

Thursday, 19 March 2015

Solar storm blindsides Earth, and an unusual eclipse...

The Sun is generally a very nice thing to have nearby, especially because we'd all freeze to death without it. But this week the Sun threw a surprise at us: A combination of events led to a storm of solar particles crashing through the magnetic field that protects Earth. On the ground the only effects are a very slight (very, very, very slight) increase in radiation levels, but 20 or 30 km up the particle storm has been crashing into the upper layers of our atmosphere, resulting in Auroras as far south as the midlands of England. I live in Edinburgh, where aurora are rare but not unheard of. A bright one would be a real treat.... so it was cloudy.
Never mind - for at least some people the view was astounding...


Above: To be fair, from this vantage point you'd probably be so bored with astounding sights that you'd crave mediocre reality tv.... Courtesy of NASA
The eclipse:
Tomorrow is solar eclipse day - but it's only visible as a full eclipse in a few places (check this link to see where), a lot more places will see a partial eclipse. The difference is that this is full:


..... and this is partial:


Both are pretty damn spectacular, here's a good link to follow for safe ways to watch. Follow that link guys - looking at the Sun directly is a good way to hurt your eyes, and never, ever try looking at it through a lens or mirror, for this very good reason:


Above: Remember that Bond villain with the giant space mirror, that melted the ice palace and tried to vaporise Bond in his invisible car? No, I'm not drunk, that was actually the plot, and incredibly the giant space mirror is fairly plausible...

This week's eclipse will be a little bit unusual (having the Sun go out is a fairly unusual event all by itself - but there's more!): As well as being a solar eclipse it will also be a super moon (when the moon is closer than usual to the Earth) and a spring equinox. 

On top of that, eclipses themselves are far weirder than most people realise....

Warped space:
 A full eclipse lets astronomers see how the space surrounding the Sun is warped. The Sun's gravity is enormous - after all it outweighs the entire rest of the solar system 100 times over. That gravity causes (or perhaps is the result of, depending on your point of view) a massive warp in spacetime. During an eclipse it's possible to see stars whose light passes right by the Suns surface to reach us - and we can see that the distorted space around the Sun throws the light off its proper course, making them appear in the wrong positions...

Warped time:
During an eclipse we can look into the space near the Sun's surface - and time runs more slowly there. If you could fly a very heatproof space ship to the suns surface and stay there you'd find that the rest of the universe was running 66 seconds a year faster. Over it's five billion year history this adds up, meaning that the Suns space time warp has pulled it nearly 10,000 years into the past relative to Earth.

They're dying out:
Solar eclipses as we know them are unique to our time: The solar eclipses as we see them today happen because of a weird coincidence - the Moon is 400 times smaller than the Sun, but it's also 400 times closer. but the Moon constantly moves away from earth, at a rate of 3 cm per year, so eventually the moon will be so far away it no longer blocks the Sun's light, and our eclipses will be reduced to weedy things like the ones that happen on Mars due to its tiny moons:

Above: A tiny Martian moon makes a weeny sweet ickle mini eclipse, as seen by one of our robot rovers... Courtesy of NASA

They look even better from space: 
From the space station eclipses look like this:

Above: That's a big shadow. Even for a Game of Thrones finale that's a lot of dark... Courtesy of NASA

It's always an eclipse somewhere (in space): 
The eclipse is caused by the Earth passing through the Moons shadow, so the eclipse is a moving place not just a one off event - somewhere out in space there is always a spot you could travel to where you'd see an eclipse. This something that has been seen by some spacecraft, when their paths take through the right spot...

Bands of shadow
As the centre of the moons shadow approaches, and the sun is just a thin crescent, the air turbulence that makes the stars twinkle starts to affect the tiny sliver of the Sun that remains - this causes huge bands of shadow to race around he landscape as the totality approaches:

Elsewhere in the universe:

Staying with the Moon:
The biggest volcano on the Moon has been mapped using a new technique that measures the radioactive signature of the rocks it produced, and a history of unimaginable power has been found. In its day the behemoth threw radioactive rock hundreds of kilometres from its core...

Volcanoes for Ceres? 
The Dawn mission continues to close in on the Dwarf planet Ceres, and as it does so the debate over the bright spots on the surface is heating up - perhaps in more than metaphorical ways. The Herschel space telescope detected what seemed to be plumes of water vapour over Ceres. Although the telescope could only plot the position of the plumes crudely, if you compare plumes and bright spots... ....voila, they match.

Above: A comparison of the water vapour and the surface map, courtesy  of the folks at unmannedspaceflight.com
And there's more: The brightest spot is visible as it rotates over the dwarf planets horizon - if it were a bright spot on the crater floor then the crater rim would block it at some point before then, so the bright spot must also be a high spot.. None of this is conclusive, but it is starting to suggest cryovulcanism of some sort - and where there's a cryovolcano there could be liquid water, and if there's liquid water then Ceres would be a habitable world....

News from Rosetta:
This week is the 46th LPSC conference, and there's a lot of new information coming out. The Rosetta team have reported finding long chain organic molecules called on the 67P comet, which suggests a kinship to comets like Halleys comet where the same molecule was detected. They also have a new theory to explain the 'windblown' dunes and other features on the comets surface: The soil of the comet is made of particles either two large or too sticky top be affected by the thin gases of the comets atmosphere, so the team has proposed that a similar effect is being caused by grains ejected from vents and bouncing across the surface

JPL develops helicopters for Mars: 
JPL has always had problems navigating its Mars rovers, mainly because the terrain there is so unforgiving. Now they think they've cracked the problems of aerodynamics in the thin martian air, and plan to develop teeny scouter helicopters to run ahead of the main mission and chart a safe route.

Elsewhere on the internet:

Extremely bright meteor over Loch Ness.

 One in three stars have planets in their habitable zone.

New spaceplane proposed.

Born in sight of a monster.

Ice fueled space drives

Whole new island born. 

'Y' shape floating in Venus's clouds

New map of Mercury



Water on early asteroids?

Sunday, 15 March 2015

Q and A with a cosmic ray hunter...



Q and A with a cosmic ray hunter 

Nature usually manages to outdo humankind's best achievements: We have the tallest building (Burj Khalifa in Dubai at 830 meters), but nature has Olympus Mons on Mars (27,000 meters). We have electricity, but nature has giant lightning on Jupiter and Saturn.

 Above: Jupiter and Saturn are giant planets with nothing but giant terrifying weather, did anyone think the thunder and lightning would go 'meow'? Yet these scientists seem quite surprised.... Courtesy of NASA

We even built the atom bomb, but the Sun is a nuclear explosion so big its own gravity keeps it all in one place. It's like playing cards as a child, against your mean uncle: You never win, except when he lets you - and then he makes damn sure you know he let you win....
Above: Olympus Mons, the biggest volcano in the solar system. It's showy if you ask me. Courtesy of ESA
You wouldn't think nature would try to compete with us over particle accelerators though. But it has - and to show us puny humans what it can do nature has given us 'cosmic rays' - ultra high speed subatomic particles from space. And, yes, I know that they should be called 'cosmic particles' - the name is a historical accident. It's not my fault, I swear.
Look there's nothing I can do, ok? Everyone's used to calling them rays now.
Ahem. To get all technical: Cosmic rays are ionised atomic nuclei, flung into space at immense speeds by some of the most powerful things known in the universe - solar flares, supernova, quasars - and perhaps by undiscovered events even more powerful.
Above: A model of an atom, showing the nucleus and the surrounding electrons.The simplest atom, hydrogen, has just one proton in the middle, and one electron. 'Ionised' means that one or more electrons are missing, which gives the atom a positive electric charge. Courtesy of livescience.com
These tiny, tiny, pieces of matter are nature's extreme racers, but only since 1991 have we realised that some are bizarrely fast - so fast that it's hard to imagine what could have thrown them so hard across the universe. So fast that, had you told a physicist prior to 1991 that cosmic rays went that fast they'd have laughed.

Above: Our imaginary physicist wouldn't have laughed like Mr Burns of course. Unless he knew something you didn't about where the cosmic rays come from, and how they held the secret of UNLIMITED POWER....
But in 1991 Earth was hit by a cosmic ray that astronomers the Oh My God particle*: It was only a single proton, but it was travelling so close to lightspeed that it had the same momentum as a fast pitched baseball - 40,000,000 times more than a proton from the LHC accelerator. Time had slowed down for it** so much that the whole life of the universe would have lasted only 16 days from its point of view.

[By the way: Particle energy is measured in 'eV' -  1 eV is the amount of energy gained by an electron passing between the terminals of a 1 volt battery. Remember that, it'll help you make sense of some of the absurdly huge energy numbers you're about to meet....]

After the OMG particle the hunt was on, and more extreme particles were found - we now know that cosmic rays with such ridiculously high energies are rare, but real. And because things travelling impossibly  fast are worrying and fascinating, we began building observatories to study them.

Above: This weird looking thing is the Milagro cosmic ray observatory - it has several meters of water over the top to screen out lower energy particles. Looks like it'd fun to bounce up and down on, doesn't it?
One such observatory hunting ultra high energy cosmic rays is the Telescope Array Project, a collection of specialised telescopes and scintillator detectors out in the quite and dark of the desert. Recently they found evidence that the highest energy cosmic rays might be coming from the same part of the sky. I had the chance to ask John Matthews, a University of Utah research Professor who works on the project, a few questions by e-mail on what its like working with some of the most extreme particles in the universe...

John:
Thank you ever so much for talking with me. Could you explain to us why the array was set up to study cosmic rays, and what you’re hoping to learn about the universe from them?

Professor Matthews:
At the lowest energies, where they are most frequent, they are passing through us all the time.  However, as you start to move up in energy they become rarer and rarer. In fact, for every order of magnitude you move up in energy, the rate of arrival drops off by about a factor of 1000.
There are some ideas on how to generate cosmic rays at lower energies, but as you move to higher and higher energies, it becomes harder and harder to explain just how it happens that a cosmic ray of these ultra high energies were accelerated. When one is [artificially] accelerating a charged particle, like a proton, one must contain it in a magnetic field while one acts to accelerate the particle over and over again. Thus, we need a large confinement space where there is repeated acceleration of the particles. Here on Earth, we call these particle accelerators.One is at Fermilab near Chicago, more recently, one hears more and more about the LHC (Large Hadron Collider) near Geneva, Switzerland. The limits on the technology allow us to accelerate particles to about a few times 1000,000,000,000 eV.
Out in the "Wild", we observe cosmic rays with as much as 300,000,000,000,000,000,000 eV of energy. How were they accelerated to such energies? What kind of objects are these that are capable to do this? They must be extremely violent: How large are they?
We hope to find sources of ultra high energy cosmic rays and if we are able to do that, we would like to further study these objects to better understand our universe.

John:
There are low energy, high energy, and ultra high energy cosmic rays, as well as cosmic rays that are different types of ionised nuclei. How do you detect the differences between different energies and types?

Professor Matthews:
To study different energy cosmic rays, we need different types of detectors. At low energy, one can build magnetic spectrometers, such as the Alpha Magnetic Spectrometer on the space station,  which measure the energy and momentum of the cosmic ray particles.....By measuring both of these, we also measure the mass or chemical composition of the particles. However, as you move up in energy, these cease to work due to inability to measure momentum - since the track of the particle no longer bends significantly in the magnetic field and the energy is no longer measured since the particles leak out of the back of the calorimeter. In addition, as energy goes up, the rate of particles drops dramatically, and one needs a larger and larger detector.
For particles above about 1000,000,000,000,000 eV, we resort to indirect measurements of cosmic rays. The Telescope Array uses the Earth's atmosphere as part of the detector. When cosmic rays hit the Earth's atmosphere, they collide with the protons and neutrons in the Oxygen and Nitrogen etc in the atmosphere. They break up that nucleus and a bunch of secondary particles come flying out of that collision.  These secondary particles still have a huge amount of energy. They collide with other nuclei and generate still more particles. This continues with kinetic energy being converted to mass energy as more and more particles are created. We soon can have a billion or more secondary particles depending, of course, on the energy of the primary cosmic ray's energy....

The Telescope Array observes this shower in two ways: Many of the secondary particles make it to the Earth's surface. We sprinkle the Earth's surface (more than 300 sq miles of it anyway) with scintillation detectors. Each scintillation detector is 3 sq m in area and they are placed on a 3/4 mile square grid. These detectors sample the density of secondary particles on the Earth's surface. They also measure the precise time of arrival of these particles. One can use this to determine the energy of the primary cosmic ray  as well as its original direction when it hit the atmosphere....
In addition to the hard collisions which add to the secondary particles in the shower, there are also soft collisions which simply excite the gas molecules in the atmosphere. The gas molecules want to get back to the ground state and do this by emitting  UV light. Therefore, the entire extensive air shower is glowing in the UV. We place telescopes on the periphery of the scintillation detector array and these observe the UV light from the air showers as they pass through the atmosphere. By looking at the signal size as the shower develops, we can determine the chemical composition (at least roughly) of the primary cosmic ray.. The proton has a much smaller cross-section than an Fe nucleus. So it is likely to penetrate the atmosphere further before its first interaction and to have more fluctuations in its shower maximum. We can also determine the pointing direction and energy of the primary cosmic ray.  One can fit a line through the track as measured by the camera and then knowing the centre of curvature of the mirror, one can fit the line and point to a plane. Using the timing info, one can turn the plane into a line within the plane and thus know the pointing direction. Integrating the area under the shower profile curve gives a good estimate of the primary particle's energy.....

John:
The 'Oh My God' particle shocked the scientific community. I know we don't see such extreme high energy particles often. How close are we to understanding where the come from?

Professor Matthews:
The Telescope Array recently published a paper with evidence of a preferred direction of ultra high energy cosmic rays. The paper indicates that there is a 3 sigma excess of cosmic rays with energy greater than 57,000,000,000,000,000,000 eV coming from a 20 degree area south of Ursa Major. With an additional year of data, that excess has become about 4 sigma [John's note: '4 sigma' is a measure of reliability - the higher the sigma number the less likely it is to be caused by chance].We are hoping that when we add yet another year of data, we will have a 5 sigma result which would allow us to announce a discovery. Of course, once we discover a source in a 20 degree cone, we will want to collect more data to see the finer structure and sources within that......
Above: The cosmic ray hotspot.

John:
Do you collaborate with other projects, and could you give us an example?

Professor Matthews:
We collaborate (at least loosely) with the Pierre Auger (Argentina)  and Ice Cube (South Pole) projects. We do some joint analyses where we combine data  to make whole sky maps and to try to better understand cosmic ray sources...

Above: The Ice Cube Neutrino observatory in Antarctica - at least the little bit of it that's above the surface. Or possibly a supervillian's B-string base, where they keep the broom closet and the mutants that didn't work out... Courtesy of physicsworld.

John:
Could you tell us about some of the research you're working on at the moment, and the plans to expand project with a low energy section?

Professor Matthews:
At the moment we have expanded one of our telescope stations and we are attempting to get funding to add a more densely packed scintillator array to study lower energy cosmic rays. Our current turn-on threshold is about 1000,000,000,000,000,000 eV.  The new telescopes look higher in the sky since lower energy cosmic rays develop higher in the atmosphere. Lower energy cosmic rays also have a smaller footprint on the Earth, hence the additional scintillation detectors. By studying these lower energy cosmic rays we hope to sort out which cosmic rays are coming from inside the galaxy and which ones are extra-galactic.
In addition, we are trying to expand the area of the main array by a factor of 4 in order to collect more of the ultra high energy cosmic rays. This will help us to study the developing source(s) which we are seeing evidence of.....

John: 
Are there any special challenges to working out in the desert?

Professor Matthews: 
We work about 3 hrs drive south of Salt Lake City in the Western Utah desert. It is a long drive any time you need to go to work or find parts to repair something - the reward is that it is very dark and quiet. We have lots of wildlife.... crows and cows which chew on our cables, birds which "do their business" on our solar panels, scorpions, black widow spiders, tarantulas, rattle snakes, etc.... It all keeps life interesting...

John:
Thank you ever so much taking the time to answer professor.
Above: If cosmic ray strikes were made visible they might look a bit like this. You can't see it here but all the Londoners in the picture are shrugging - weirder things happen in London every day. Sometimes the traffic jams even move.... Courtesy of the University of Birmingham
Elsewhere in the universe:
A 15 meter asteroid flew within 100,000 km of Earth.

Bucky ball molecules form in space:
Buckyminsterfullerene, a gigantic molecule of 60 carbon atoms in a football shape, was a breakthrough when it was first manufactured. Now it seems that  Buckyballs form naturally in space - how exactly is a bit of a mystery, but nature is full of surprises and the linked paper explores some of the possible ways they could form.

Elsewhere on the internet:

A new view of Mercury's geology

Results from the orbiting Russian space telescope RadioAstron

How spiral galaxies form, new evidence.

Milky way's central black hole feeds in bursts



*Seriously, google it.

** This is something that happens to things that get close to lightspeed. Hey, don't blame me, blame Albert Einstein.

Thursday, 12 March 2015

The surf report on Enceladus, and the weather report on Titan: Both mysterious with chance of bizarre.

The Cassini mission has been returning a lot of interesting data from the moons of the Saturn system, and on two of its most interesting worlds in particular: Enceladus and Titan.


Above: Teeny Enceladus and massive Titan float in space, together with Saturn's rings. Although when I say teeny I mean it the way astronomers use the word, which is to say 'hundreds of miles big'. Courtesy of NASA.
Enceladus, a tiny moon of Saturn with a warm sea at its south pole, has revealed another of its secrets: It may well have hydrothermal vents at the bottom of its seas. The little moon is one of the more helpful worlds in our solar system - its south pole is pierced by massive geysers that jet the seas (and any material in them) into space. This gives the Cassini spacecraft a chance to fly through the plumes and sample the sea. So far it had found salt, organic molecules.... and tiny particles of rock.

The rock particles are the clue that points towards deep sea vents on Enceladus: These particular particles need temperatures of at least 90 degrees Celcius to form. A second line of evidence that (possibly) suggests hydrothermal vents are present is the methane found venting into the atmosphere of Enceladus - hydrothermal vents are one of the possible explanations for the gas, with another being methane rich ices known as clatherates."This moon has all the the ingredients to support habitability in the outer solar system" Said Nicolas Altobelli, ESA's Cassini project scientist.

Above: To explain hydrothermal vents a bit better I give you David Attenborough. Because there's never a bad time for a David Attenborough clip. Unless there're angry crocodiles in the room with you, but then you probably shouldn't be reading this either.... Courtesy of the BBC.
 
Elsewhere in the Saturn system the giant moon Titan is revealing more mysteries. The only known moon with a substantial atmosphere, when the Cassini space mission began to pierce Titan's orange smog it found a world soaked in liquid natural gas, and covered in sands and soils made of organic compounds often too complex to identify. Speculation on what, if any, kind of life could exist there has recently been stoked by computer models of cryogenic cell membranes, and the discovery of odd chemical imbalances between the surface and atmosphere. The moon holds plenty of other things that are just plain mysterious, like the disappearing islands or why there've been no definitive sightings of waves on its seas.

Above: An island on Titan's methane sea appears out of nowhere. Once there the space penguins try to catch it with a giant red hula hoop. Not really, everyone knows space penguins can't stand red. Courtesy of NASA
Amid all this mystery and alieness you'd think that something as simple as the weather report would be a mere detail. But even here Titan throws curve balls - or, in this case, strange raindrops: Just as its seas and lakes are filled with liquid methane and ethane, so its rain is made of those things. Cassini, flying high above Titan, showed ground wetted by a recent methane rainstorm - a first but not that surprising. What was odd was what happened next: Parts of the surface started that were rained on started getting brighter, reaching a maximum weeks or months after the storm and staying that way for months. Then the brightened areas gradually shrank, reducing in extent, and eventually faded.

Why Titan's surface would react this way to rainfall isn't clear - it isn't  a chemical effect, although chemical weathering does happen on Titan.One possibility the paper describing all this raises is that the rain could have dissolved something in the soil which would wick upwards towards the surface then settle as a layer of crystals as the soil dried out. Over time the chemical would revert to its natural state in the soil - that'd explain why only certain areas were affected. Another possibility is that evaporation of the methane sitting on the surface after the rainfall cooled it enough for it to freeze as a long lived layer of tiny crystals.
And, this being Titan, there's always the possibility of something entirely unknown and weird going on...

The other bit of news from Titan - in a paper published by a lot of the same researchers as the first - is a possible detection of waves on the surface of one of its northern seas, Punga Mare.  The glassy calm of Titan's seas has been a serious head scratcher for scientists. Suggestions on why range from the seas being like syrup in texture, to actually being vast plains of jelly. As much as I like jelly the simplest explanation is that the winds,  for some reason,  simply haven't yet got strong enough to make waves. The paper's authors now think they're seeing signs of waves beginning to form as the northern seasons turn and the winds pick up, although they're not certain yet.


Above: In case you haven't heard of the Cassini mission here's a quick run down. Although I'm silently judging you for not knowing. I'm mean like that. Courtesy of NASA. 

Elsewhere in the solar system:
Evidence of a possible habitable zone on Mars isn't such big news these days, but a recent find underscores how world with lots of ice and any kind of volcanic heat can produce possible habitats fr life. Rising magma beneath a glacier field of may have heated areas where it breached the surface to make subsurface zones of warm water.

Arecibo strikes again:
Using its unique ability to send 'probes'  of radio waves to other worlds,  the giant radio telescope has returned sets of maps of Venus...  Years apart -  the team plans to use this method to check the Venusian surface for changes that might indicate active volcanoes or other processes.

Magnetic reconnection is a process that turns magnetic energy into heat and results in some of the biggest and most inexplicable explosions in the universe -  in particular it causes flares on our own sun with the energy of millions of hydrogen bombs.  The Magnetic Multiscale  Mission, consisting of four spacecraft that will fly in formation through magnetic reconnection events in space and build up a picture of how these phenomena work, is designed to help us unravel this mystery.
 
Above: How the four satellites will deploy. The spacecraft have actually launched, but  couldn't find a video online yet, so we'll have to make do with this and some imagination. Courtesy of NASA
 
A cometary tale of survival?
ESA will begin attempts to recontact the Philae lander, which has been lost on the surface of comet 67P since November. The odds of the Rosseta mothership contacting the washing machine sized craft so soon are slim, but good enough to make it worth trying

Another moon with an ocean!
Ganymede, a moon of Jupiter, appears to have an ocean beneath its ice, similar to its sibling world Europa.

Elsewhere on the internet:

Gamma ray bursts from sources moving rapidly away?

SWIFT spacecraft hunts Gamma ray bursts 

Electricity shepherds biomolecules 

Milky way may be 50% bigger than expected

Curiosity rover is on the mend

Terminators liquid metal droid edges towards reality