The list of talks looks very interesting (even without my contribution!). The deadline for abstracts is now April 1st, so if you’re keen to submit a talk or poster to the session, you still can.

SETI in the UK is in a transitional phase, edging toward the mainstream as astrobiology becomes more and more commonplace in UK research institutes. NAM 2013 is going to be a great opportunity for the UK SETI community to meet – there hasn’t been sessions on this scale for several years. Also, for any UK astronomers out there who have been thinking about how their research might apply to SETI, then here’s a golden chance to find out what SETI science looks like, and what you can do to be involved. If you can’t make it to the sessions, you can check out the Facebook page setinam2013 and the Twitter hashtag #setinam2013. See you there!

In a similar vein to last week’s post, I’m proud to show you results from an outreach project I’ve been working on with Tom Targett at the ROE for the last few months.  As the result of a rather long-winded discussion of interstellar colonisation at coffee time, we got to thinking about how rigorously we could simulate conflict between competing civilisations.

Of course, we don’t have any evidence that other civilisations even exist, let alone fight each other for resources.  All we know is that conflict has been an important part of human history since time immemorial, and that we can see the origins of our penchant for tribalism and warfare in our primate cousins.

The D Day landings. Via ww2incolor.com

As it would be churlish from a scientific standpoint to assume that our aggressive behaviour is unique amongst intelligent species, Tom and I felt it was safe to assume in our current ignorance that intelligent species are completely capable of conducting interstellar wars, and would do so to secure resources.

This still left us with a bit of a problem – how can you model interstellar conflict when you know nothing about the combatants? It was then that we hit on the idea of calibrating our simulations by using ‘real’ data on how alien species fight.  StarCraft 2, a real time strategy game played throughout the world, has several races of belligerents, who fight each other frequently in the domain of Massively Multiplayer Online gaming.  In a classic example of citizen science, we found that the general public had generated a vast dataset of (admittedly fictional) alien behaviour, which we could use to drive our simulations.

So, we created a population of stars similar to the local Solar neighbourhood, and seeded it with six different races, each representing one of the three civilisations (the Terrans, the insectoid Zerg and the advanced, telepathic Protoss), carrying out one of two strategies.

A snapshot of the simulation. The colours represent the space colonised by each race

Not a snapshot from the simulation…

Like all good science, this work started as a rather rambling lunch-time conversation about how humans should physically explore the Galaxy.  We took our inspiration from humankind’s exploration of the Solar System:

The paths taken by the Voyager spacecraft as they explored and left our Solar System

The Voyager spacecraft were launched with the primary function of exploring the outer Solar System planets and their environment, but have also travelled to far greater distances from the Sun.   Voyager 1 remains a scientifically viable instrument, despite being over 11 billion miles from its launch site – signals from the spacecraft take over a day to arrive at Earth despite travelling at the speed of light!

How the Voyagers managed to accelerate themselves sufficiently to travel so far from the deep gravitational well of the Solar System is a neat example of the conservation of energy.  The planets possess an enormous amount of energy stored in their orbital motion, and this energy source can be tapped using a gravitational slingshot maneouvre.  The probe slings around the planet, using the planet’s gravitational field to change its trajectory and fling it in a different direction.

How the slingshot looks like from (top) an observer on a planet surface and (bottom) an observer moving relative to the planet (via Wikipedia)

An observer standing on the planet’s surface will measure the speed of the probe to be the same before and after the slingshot (see diagram), but the planet itself is moving.  An observer floating at rest will measure the speed of the probe as it leaves to be different from the speed it possessed when it arrived at the planet.  If the planet and the probe are moving towards each other during the slingshot, then the probe’s speed will be boosted.  Alternatively, if the planet is moving away from the probe as the probe begins the maneouvre, then the probe’s speed will be decreased (this can be used to capture satellites in orbit).

The probe and the planet are exchanging momentum during the interaction.  If the probe speed is boosted, the probe is depleting the planet of orbital energy!  Luckily, the amount of energy it extracts is minimal in comparison to the total available energy, so Jupiter and Saturn aren’t going to be crashing into the inner Solar System any time soon.

This brings us back to our lunch-time conversation.  Gravitational slingshots need a massive body that orbits around some central object.  This is obviously true for the Solar System, but this is also true for the Galaxy.  The Galaxy has a centre, occupied by a supermassive black hole.  While the Sun is not gravitationally bound to it, it does orbit around it at approximately 200 km/s.  In other words, there’s plenty of orbital energy out there for interstellar probes to use!

We calculated that if a probe carries out a series of slingshots as it tours the Galaxy, the probe can be accelerated to approximately 1% of the speed of light without shipping enormous amounts of fuel (bear in mind Voyager 1 is travelling at 0.003% of lightspeed).  This got us thinking about Fermi’s Paradox.

Fermi’s Paradox simply wonders, given the large length of time that the Galaxy has existed, and the relatively small length of time it would take to travel from end to end at a small fraction of lightspeed, why aliens haven’t shown their own presence.  This Paradox gets stronger if we consider aliens sending probes that are self-replicating, making copies using material they find along the way.  Surely, this rapid spread of probes across the stars, growing their population exponentially like bacteria, would be so pervasive that we would have spotted one by now?

In the past, when SETI scientists simulate this type of exploration, simple trajectories for the probes are used, and they all travel at a relatively high fixed speed.  We wanted to see what adding gravitational slingshots to these simulations would do.  Our hunch was that this would make Fermi’s Paradox even stronger.  The result - it does.  Adding gravitational slingshots to the probe trajectory allows even spacecraft as slow as Voyager to explore a patch of the Milky Way around 100 times faster at vanishing energy cost!

So, even if ET is somewhat frugal with its resources – one reason often proposed as a solution to the Fermi Paradox – gravitational slingshots show that’s no reason not to explore the Milky Way…

These are brown dwarfs… (Hubble image of Orion)

…and these are dwarves wearing brown

Science is a global practice.  It just so happens that most scientists have adopted English as lingua franca, requiring non-native speakers to be able to use it to communicate with the admittedly lazy native speakers.

On the face of it, English is not exactly a good choice for a universal language (of course, it wasn’t exactly chosen, but rather foisted upon much of the world during the colonial period, and the British Empire cemented its familiarity and use).  Its history is the history of a perpetually invaded and embattled island kingdom.

The language is a heady mix of Germanic, Latin, Norse, French, and other invasive languages, evolving from a creole in the medieval period to the modern English we know today.  As a result, it’s unmercifully bloated and obscure, with countless words, a partially collapsed declension system, no gender, a dizzying list of irregular verbs, and a baffling range of dialects and accents to confuse and terrify.  The situation is made even worse thanks to neologisms, new words that enter the language at a rate of several thousand per year.  Literature and other media makes their presence felt constantly (case in point, this year’s most famous neologism, omnishambles).

There are few pieces of literature with impact as great as Tolkien’s The Lord of the Rings.  While he was not responsible for the coining of the term, Tolkien adopted the plural “dwarves” for his fictional race of diminutive stonemasons, calling it

a piece of private bad grammar

The fact that this piece of bad grammar would be part of the third best-selling book of all time has understandably led some to accidentally use it (here’s an example from the Royal Astronomical Society’s own pages).

Am I pedantic? Absolutely.  It doesn’t change the meaning of the sentence, only the length of the last syllable in one word.  But I’ve accepted my fate as someone who’ll be frequently irritated by what I consider to be bad usage.  There’s not much you can do about an evolving language, especially one as beaten up and malleable as English.  Amongst native speakers, we can guess how quickly an irregular verb will regularise, and non-native speakers are developing an English variant that may soon be inaccessible to the native.

I’ll just need to focus my pedantry somewhere else…

Wish You Were Here? Searching for Exoplanets is a collaboration between scientists and artists led by Tania Johnston of the Royal Observatory Edinburgh’s Visitor Centre, funded by a Scottish Government Engagement Grant, with contributions from the Royal Society and the Scottish Universities Physics Alliance.  Documentary film-making students at the Edinburgh College of Art were given a brief: to make a film about exoplanet research in Scotland.

After pitching their ideas to a judging panel (of which I was a member), two teams of two students were given the green light.  Researchers at the University of Edinburgh and the University of St Andrews starred in the two films, which were recorded in late 2011 and early 2012.

The two films, “Into Deep Space” (in which I featured) and “Close Distance“, got their premiere at the Edinburgh Science Festival, and have been touring the country ever since.  They’re certainly not the usual science documentary – the students have come at it from a very different angle, and it’s a refreshing take on the passion that scientists (and amateurs) have for their chosen field.  And the judges have enjoyed it, also.  “Into Deep Space” won an Honourable Mention at the Imagine Science Festival, and is nominated for several other prizes!

Most of the screenings have been attended by at least one member of the cast, to answer any questions the audience might have.  The films have been shown all over Scotland – I’ve just come back from a screening on Orkney, as part of their Science Festival.

Taken just outside the Orkney Brewery (an important visit during public engagement)

It’s been a real treat to see these films, and to see them go on tour and hear such favourable feedback.  If you want to see them on the big screen, then there are plenty of opportunities: if you can’t wait, whet your whistle on the trailers at the links above, and come to the Peebles Science Festival tomorrow (Wednesday 19th).  I’ll be there – feel free to come say hi! And if you see the films, let us know what you think: leave a comment, or tweet us with the hashtag #WYWHexoplanets.

The Curiosity rover being installed inside its atmospheric entry capsule. Credit: NASA/ Glen Benson October 2011

It’s shaping up to be an important week for NASA.  Their Mars Curiosity Rover should be touching dirt in Gale Crater by 0631 BST Monday.  It’s a powerful beast, carrying about 10 times as much mass as its ancestors, powered by a plutonium-238 thermoelectric power generator.  It will combine the camera mounts, six-wheel drive and suspension technology inherited from the Spirit and Opportunity rovers with the ability to conduct onboard sample analysis, scooping up Martian soil and carrying out a series of tests for organic compounds.  It will even be able to use a laser to vapourise rocks and study the remains, continually improving our understanding of Mars as a potential ancient habitat.

This is no mean feat – just getting a monster the size of Curiosity to the surface requires a finessed landing process.  Previous landers have used airbags to soften the impact of landings, but Curiosity is too massive for that.  This problem is exacerbated by Mars’ thin atmosphere, providing little air resistance to the capsule hurtling toward the surface.  An innovative “sky crane” landing system will require the capsule to slow to a hover above the surface, and then slowly deploy Curiosity to the surface by means of an umbilical tether.

Curiosity being deployed via the sky-crane. Credit: NASA

Despite such an ambitious plan to reach the Martian surface, NASA have set their mission objectives a little lower than perhaps expected.  With such a formidable rover roaming around Gale Crater, it would not have been surprising to hear NASA claim they were searching for living organisms.  Instead, they modestly hope to find “the ingredients for life”, a much more likely outcome given the lack of subsurface aquifers originally thought to be there.  Previous missions tried and failed to find the aquifers, now consigned to the same dustbin as Schiaparelli’s canals.

This throttled-back candour seems to be reflected in all of NASA’s recent decisions.  With budgets in seemingly interminable flux, and each administration dreaming of unrealistic resurrection of the manned space program, the agency has been forced to box clever as of late.  It is still licking its wounds from the JWST budget scandal, as well as the less public academic backlash from the media circus surrounding missions such as Kepler (see e.g. here).

They have the misfortune of two quite disparate audiences to manage expectations for – the nonspecialists, who fund it, and the scientific community, who drive its scientific aims and clarify its most important tasks.  Each has their own aims and agenda, and each are disappointed when things “go wrong” according to their beliefs as to what “going right” is.

In this thorny environment, NASA’s recent decision to open up manned spaceflight to the private sector is an attempt to walk a difficult tightrope.  Outsourcing the cost of the post-Shuttle crew vehicle design and construction is a tick in the box for an impoverished electorate who wish to rein in expenditure in tough times.

SpaceX’s Dragon Capsule in the robot arm grapple of the International Space Station, prior to docking

Scientists will be mollified by the choices of outsourcing.  SpaceX’s Dragon (above) has already demonstrated its crew vehicle in an unmanned mission to the International Space Station earlier this year; Boeing’s track record in spaceflight goes all the way back to Apollo; and Sierra Nevada is the inheritor of a previous NASA mini-shuttle design.  These three choices are the end of a shortlisting process, with many losers having to go it alone with “commercial” intentions, including Blue Origins, a startup from Amazon’s Jeff Bezos.

This cautious, softly-softly approach is to be welcomed in these difficult times.  Funding is evanescent in these times, and developing missions with achievable, yet still laudable goals is important.  Better still, use the resources in the private sector rather than compete with them.

It’s hardly the “to boldly go” statements that get scientists into the field, but some necessary realpolitik.  Goose chases (however fun) are frowned upon by people with bags of money.  And no, the irony of that last statement is not lost on me

Filed under: Astrobiology, Astronomy, Technology Tagged: Boeing, Dragon, mars curiosity, NASA, Sierra Nevada, sky-crane, SpaceX ]]> http://wellbredinsolence.wordpress.com/2012/08/05/nasa-hedges-its-bets-on-curiosity-and-the-post-shuttle-future/feed/ 0 dh4gan 597996main_2011-10-11-2_full 593484main_pia14839_full_Curiosity's_Sky_Crane_Maneuver,_Artist's_Concept dragon-grapple-3 http://wellbredinsolence.wordpress.com/2012/05/13/planetwatch-channeling-le-verrier-in-the-koi-872-system/ http://wellbredinsolence.wordpress.com/2012/05/13/planetwatch-channeling-le-verrier-in-the-koi-872-system/#comments Sun, 13 May 2012 18:17:55 +0000 Duncan http://wellbredinsolence.wordpress.com/?p=1119 ]]> In August 1846, Urbain Le Verrier announced to the French Academy his prediction of a previously undiscovered planet.  He had studied the motion of Uranus, and concluded using Newton’s Law of Gravitation that the small deviations he had witnessed in its orbit were due to gravitational perturbations made by the proposed planet.  John Adams, also working on the same hypothesis, was barely beaten to the punch.  The new planet was Neptune, and its discovery was a triumph of the scientific method.  Its existence was predicted without ever having been observed (although it is said that Neptune had been observed in the past but never correctly identified).

One hundred and sixty five years later, astrophysicists have repeated Le Verrier’s method for the first time in an extrasolar planetary system.  The KOI-872 system is one of the Kepler Space Telescope’s Objects of Interest, and its data is public.  The Hunt for Exomoons using Kepler Project (HEK, which I’ve blogged about before) has analysed this data, and detected several transiting extrasolar planets in the system.  Hidden inside the transit data from planet b is the gravitational tug of the hidden planet c:

The gravitational tug of planet c disturbs the orbit of planet b, making its transits shuffle around in time (known as Transit Timing Variation or TTV).  TTV, and its cousin, Transit Duration Variation or TDV, are potentially capable of detecting exomoons, hence the HEK project’s interest in cataloguing them.  The TTV and TDV generated by exomoons are pretty small, but the TTV seen here is vast – this variation indicates that planet c must have a mass close to that of Saturn, orbiting the star every 57 days.  There are also signs of a Super Earth nestled in there as well (planet d, unconfirmed), with an orbital period of around a week.  Here’s my somewhat piffling cartoon of the system as it stands, with distances from the Sun beneath:

The eccentricity of all planets is similar to that of the Solar System planets (i.e. almost zero), and all the planets appear to be orbiting in the same plane.  This is more evidence that multiple planetary systems occur fairly frequently, and coplanar solar systems like ours are not a fluke.  More than this, this is proof that the TTV signal can be detected, and that the HEK team are on the right track.  Next stop, an exomoon!

It does indeed suck that this is a zero-sum game (in fact, probably negative-sum).   Sadly, from my view it looks like the ire surrounding JUICE would have been stoked and pointed at whoever won this contest.  After all, astronomers have begun crying foul so loudly out of a justified fear for their own fields.  Without ATHENA, X-Ray astronomy (a necessarily space-based pursuit) will struggle in the coming years.  NGO was also a great white hope for the gravitational wave community, it being the survivor of  LISA, a similar observatory which fizzled after NASA pulled out.

I’m not here to point the finger, or begin arguments.  I just want to mention that while JUICE might not be good for everyone, it is good for many other people.

One thing I’ve heard many times from detractors is that Juno, a NASA mission, is already on its way to Jupiter.  True, and admittedly there are overlaps in the missions, but its ultimate objectives are completely different to those proposed for JUICE.  Juno will map the magnetosphere of the planet, and assess its atmospheric water content – ultimately, it hopes to assess the nature of Jupiter’s core, a long standing question in planet formation theory. More than this, Juno will reach Jupiter in 2016 (after a quick swoop past Earth in 2013 to pick up some extra momentum we’re not needing).  JUICE won’t arrive until the 2030s, long after the Juno data is picked clean.

Artist’s impression of Juno as it arrives at Jupiter (Credit: NASA/JPL)

JUICE will look at Jupiter, its atmosphere, its magnetosphere, but its key science goal is to study the moons – Ganymede, Callisto and Europa in particular.  There are plenty of unanswered questions about the moons – questions thrown up from earlier missions such as Galileo.  We know these moons are icy, but how icy? Is there liquid water on these moons, and in what quantity?  The thickness of the crust of ice on Europa’s surface is currently a guess based on some incomplete data and extrapolated from models.  If we ever wanted to send a probe to the Europan surface, it would be good to know if we were landing on thin ice.

This leads us to a second comment that’s repeatedly levelled out missions of these type, from failed Mars missions to Cassini flybys.  The promise of liquid water is the promise of life on another world.  That’s all it is right now, a shaky promise built on (necessary) terrestrial chauvinism.  This is painted as a wild goose chase, assumption built on assumption, and JUICE’s mission goals are repainted into a straw-man argument that is easily demolished (interestingly, this argument might apply to NGO, which is also attempting to detect a theoretically defined but never seen phenomenon, but it is made far less often).

Understanding moon composition is not just so we can shake out the exo-bacteria – it also helps us to figure out how these objects formed in the first place.  If you thought planet formation was a tough nut to crack, then moon formation is a doozy.  We think they form out of discs that surround planets (after they are formed from discs that surround stars).  The circumplanetary discs are fed from the circumstellar disc, which then feed on to the planet or into coalescing moonetesimals (as you can see, the potential for jargon is hilarious).  Finding some slime mould would be an amazing bonus, but not finding mould would not be a mission failure.  The science haul from JUICE includes magnetospheric data, exospheric data, topographical surveys of the moons’ surfaces…all information that could help describe the early Solar System, not to mention the potential exomoon systems that exist out there.  Characterising these missions as merely chasing puddles does them an injustice, just as it would be unfair to characterise an X-Ray observatory as simply searching for large explosions.

There is one fair comment to be made against JUICE.  That it is an experiment, not an observatory.  When money is tight, space missions should be flexible, able to carry out science goals across all the fields of astronomy.  JUICE is limited to studying one moon system.  Of course, there are many observatories in existence (not many for X-Ray or gravitational waves, but there are some), and there are many experiments (the LHC is probably the most famous example).  But we need all sorts of approaches to make the scientific community work to the best of its ability.

If you asked me which mission astronomers needed most, I might well have said ATHENA, as it is the most flexible, and probably the quickest to deploy to a needy community.  But we have what we have – and remember that JUICE has a lot to offer us.  And ATHENA and NGO aren’t dead yet – a second round of selections are expected to be made by ESA, for launch in the 2030s.  Hardly the best, but certainly not the worst outcome.

The Mearth Project, composed of 8 16" telescopes controlled robotically. Credit: Cfa

When GJ1214b was discovered, the team were able to constrain its mass between one and ten Earth masses from the period of the planet’s orbit. Combined with the direct measurement of the planet’s radius (2.7 Earth radii), the Mearth team were able to infer that the planet’s density was close to that of water.

This is more than just a big quivering blob of liquid.  The core of this planet would presumably have some very exotic forms of water that exist only at very high pressures, such as Ice VII, which has a bizarre crystalline structure compared to regular ice, or superfluid water, which acts as if it has no friction or viscosity.

Even regular, old-fashioned steam would seem to exist here.  In 2009, theoretical models underestimated the apparent radius of GJ1214b, which the Mearth team interpreted as the presence of a steamy atmosphere above the surface.

Now, 3 years later, the Hubble Space Telescope has been brought to bear on GJ1214b.  Hubble’s Wide Field Camera 3 was trained on the planet as it went through a transit.  As the planet obscures its host star, starlight shines through the planet’s atmosphere towards Earth.  The atmosphere preferentially absorbs at specific wavelengths, leaving a chemical fingerprint in the light’s spectrum.

An artist's impression of GJ1214b transiting its host star. Credit: CfA

The fingerprints might still be a little smudgy, but data suggests the atmosphere is at least 20% water, probably much higher.  The best guesses for the composition of the planet would appear to be an icy, rocky core with a very watery atmosphere and a healthy pinch of hydrogen and helium.  How exactly the planet ended up quite so watery is unclear – it would almost certainly have had to form quite far from its host star, beyond the distance at which ices melt (usually called the snow line), and migrated inwards.

Could it be inhabited? A large surplus of water in a variety of phases is certainly a boon for life on Earth, and we know how diverse and teeming the oceans are.  But bear in mind the temperature on the surface was estimated to be around 200 degrees C.  This would certainly lead us to say that terrestrial life would struggle to live here, but the oceans of GJ1214b will be weird to say the least, containing bizarre ice and superfluid water…if there was life, it would have to be pretty weird too.

A schematic of the potential planets in the Alpha Centauri system (Credit: Javiera Guedes)

Alpha Centauri A and B compose a binary system (Proxima Centauri may be closer to Earth, but it’s very far away from the other two Centauri stars).  The two stars A and B orbit each other in an ellipse, with a period of about 70 years.  We’ve been reasonably convinced that either Alpha Centauri A or Alpha Centauri B are suitable stars to host extraterrestrial exoplanets, mostly because they are quite similar to our own Sun, and the orbit of the binary system is sufficiently large (at closest approach, the stars’ separation is similar to that of Saturn from the Sun) that we’ve been able to more or less ignore Alpha Cen A when looking at Alpha Cen B’s habitable zone (and vice versa).

But as we’ve learned over the last few decades, we shouldn’t be too complacent about ignoring factors that could influence a planet’s climate.  Especially when what you’re ignoring is an extra Sun in the solar system.  Even if the second star only accounts for 1% of the total heat being delivered to a habitable planet, that 1% could have an important effect on the fate of the planet.

So I decided to see what would happen to planets in the habitable zone around Alpha Centauri B if I added in the starlight of Alpha Centauri A.  When I added Alpha Centauri A to a simple climate model which contains a single planet (on a variety of different orbits) and Alpha Centauri B, I found that that small bit of extra sunlight can make a real difference.  It can make some planets more habitable, and some less habitable.  In fact, it can make the mean temperature of these planets fluctuate by up to 3 degrees C.  Now these climate models I run are very simple, but remember that a few degrees C has important consequences – this is why world leaders are trying to agree to reduce C02 emissions.

Life on these planets with wobbling climates would have some unique characteristics.  Circadian rhythms (such as our “body clock”) are calibrated to sunlight and the length of the day.  But planets around Alpha Centauri B have two types of day – a normal day like we have on Earth, due to the planet spinning on its axis (a “B-day”), and a second type of day defined by when the planet undergoes a full spin on its axis relative to the distant ACen A (an “A-day”).  Now the strength of sunlight from A will change as A orbits around B, because the orbit of A around B is elliptical, and quite elliptical at that.

So Life around Alpha Centauri B could have two separate sets of circadian rhythms – one calibrated to star B, and one to star A.  Migration patterns will be affected by the fluctuations in temperature – imagine birds that only live for a few years suddenly upping sticks and heading north or south because of a deeply ingrained instinct to move every 70 years because part of the planet’s surface suddenly becomes uninhabitable!

The results from one of my computer models. This shows the fraction of surface that is habitable on this particular planet vs time. The dips in habitable surface are due to Alpha Centauri A passing close by and heating it up. The equator is too hot for liquid water to exist, and that band of inhospitability increases as Alpha Centauri A goes by

There’s still more to do, of course – these models don’t incorporate the effects of Alpha Centauri A’s gravity, which will slightly change the planets’ orbit, and produce an extra set of periodic fluctuations known as Milankovitch cycles.  In any case, we can see once again that looking for habitable planets is not as simple as it may first look.