Monday, 27 July 2015

The Problem with Earth 2.0

Like many others, I'm starting to develop a severe twitch whenever I see the words 'Earth-like' or 'Earth twin' or 'Earth-2.0'.  The twitch was pretty maddening last Friday, when the the discovery of Kepler-452b was announced by NASA and shared globally by media outlets, including the BBC report here.  The paper, by Jenkins et al. (arxiv), describes the detection of a "possibly rocky" world 1.63±0.2 times the radius of Earth, orbiting a Sun-like star on a 385-day orbit.  In fact, the probability of this world being rocky lies somewhere between 49% and 62%, according to models and their statistical analyses.  So it's a 50:50 chance of being a rocky world.  The star is slightly older and larger than our own Sun, and at 1400 light years from Earth it's going to be an immense challenge to learn more about the conditions on this world.
Stunning artists impression of newly-discovered Kepler-452b.
But we should recognise the artist license here, and that these
works don't begin to portray the uncertainty!

Taking a step back for a moment, the very fact that our species has been able to build machines that today, in the early 21st century, are capable of discovering worlds that *could* be similar to our own is pretty breathtaking - an incredible feat of human achievement that we hope has been matched and exceeded by other civilisations out there in our universe!  Exoplanetary science has advanced at an incredible rate, with understandable excitement surrounding new discoveries and what these new worlds might be like.  The problem is that our excitement is sometimes overreaching what we truly know about these distant worlds.  Sadly, the answer to that is "next to nothing."

The paper by Jenkins and the Kepler team is very clear about this.  They write about probabilities and present the facts, as scientists should be doing.  There are subtleties and complexities in the reduction and interpretation of these data that could take years to fully understand, and science is honest about all this. The problem is that the media, by and large, are after a catchy headline to make us buy their papers or click on their ads. And public outreach departments for universities, businesses and space agencies all know this.  This chain means those subtleties are lost, and we're left with headlines about the discovery of an Earth twin.  And it's that which drives so many of us nuts.

The problem is that the community starts to look like the 'boy who cried wolf.'  Yes, we're now another step closer to the goal of finding an Earth (in this case, we know so little about this world that it could be rocky, but it could also be gassy and very unlike our home).  And yes, this could be the closest we know of to date.  But with every step, these big media releases diminish the next discovery.  Media outlets will work harder and harder to push their headlines, using more and more hyperbole to describe the new results.  Eventually, will people care when a true Earth twin is discovered by some future telescope?  As scientists on Twitter have pointed out, this regular news headline is becoming as familiar as the story of water on Mars ("yawn, we've discovered evidence of Martian water.... again...").  And one day, will we be saying "scientists have discovered more biomarkers in exoplanet BLAH756b's atmosphere... yawn...", because of this need to publicise work to win public admiration and sorely-needed grant money?

I'm being mean, as I've publicised things that didn't need publicising, so I can understand the temptation.  And there's the flipside - some budding young wannabe scientist might see this news and think "that's what I want to do with my life."  And that'd be a great thing.  I hope it prompts them to look deeper, follow through the hyped-up press releases and actually read the scientists' words directly.  It's what we don't know that's keeping the community so excited about these new discoveries!  What about its atmosphere? Magnetic field?  Plate tectonics?  Oceans and mountains and vegetation and life?  What if it's a small version of Neptune?  That's what get's me fired up.

PS.  Read Phil Plait's take on all this here.


Monday, 20 July 2015

Airbus DS Selected for JUICE

Seven months after the announcement that the JUICE mission had been formally adopted by ESA (November 2014), and the Invitation to Tender (ITT) released to the prospective contractors in December, we learned last week that Airbus Defence and Space (@AirbusDS) has been chosen by ESA's Industrial Policy Committee to build our ride to the jovian system.  The selection of an industrial contractor is making the whole process feel so much more real, and Airbus is expected to sign the contract in September.  That means that work could start as early as the end of the month.

Airbus DS is "the world's second largest space company," with sites around Europe in Toulouse (France), Friedrichshafen (Germany), Stevenage (UK) and Madrid (Spain).  They're very well known in planetary exploration, having built Venus and Mars Express, Huygens for Titan and the Rosetta spacecraft.  Today they're building ExoMars, BepiColombo and Solar Orbiter, so with that heritage they seem like a great choice to me.  Building the 5-tonne JUICE spacecraft will be a challenge, with its 97 square metres of solar panels to provide the juice for JUICE out at 5AU, and the requirements for an unprecedented level of magnetic cleanliness to prevent any problems with the sophisticated payload suite.

Airbus DS won the €350M contract ($389M) after a competition with a team composed of Thales Alenia Space of France and Italy and OHB SE of Germany.  From ESA:  "The contract covers the industrial activities for the design, development, integration, test, launch campaign, and in-space commissioning of the spacecraft. The Ariane 5 launch is not included and will be procured later from Arianespace."

From spacenews:  "ESA’s geographic return rules mean work-share distribution must closely match each nation’s financial input, meaning Germany, France, Britain and Italy, as ESA’s biggest members, must be guarantee major pro rata roles for their domestic industry."  That means the the individual ESA member states must get out what they put in, so everyone will hopefully get a slice of the JUICE pie...

Read ESA's press release here and Airbus' release here.

Monday, 6 July 2015

Latex Papers Survival Guide

Every now and then I spend hours of my time wrestling with Latex documents to get them to do my bidding.  I'll try to keep a record of any useful hints and tips here.

Text Highlighting:

To highlight paragraphs of text, including references:

\usepackage{color,soul}

...and then when you get to the text you want to highlight, simply add \hl{...}.  To ensure that references behave properly when using the \cite{} suite, put it inside an \mbox{} command.  I.e., use \mbox{\citep[][]{87andrews}}.


Friday, 26 June 2015

IUGG and Planetary Meeting Overload

I’m in the air returning from a relatively poorly-known meeting in planetary science, the IUGG (International Union of Geodesy and Geophysics, http://www.iugg.org/) meeting that was held this year in Prague.  These quadrennial meetings have an extremely long history, dating back to 1919 when they were first established in Brussels, but they are mainly dedicated to studies of planet Earth and its immediate environment.  There’s a smattering of ‘off-world’ topics scattered throughout the Union’s remit, but the number of Earth scientists engaging with their planetary science counterparts is relatively low.  I hope that will change, and this year myself and others convened a couple of comparative planetology sessions, hoping to attract a broad audience from across IUGG.

IUGG is one of the 31 Unions that make up the International Council of Science (ICS, http://www.icsu.org/), which also features the IAU (International Astronomy Union), famed for its demotion of Pluto from planet status.  These Unions are organised in very specific ways - the IUGG has eight Scientific Associations (cryospheric science, geomagnetism and aeronomy, meteorology and atmospheric science, seismology and Earth’s interior, geodesy, hydrological science, ocean science and volcanic science).  Each Association then has a number of commissions that operate on a more detailed level.

Within IAMAS, the International Association of Meteorology and Atmospheric Sciences (http://www.iamas.org/), I have been helping to manage one such commission, known as the International Commission for Planetary Atmospheres and their Evolution (ICPAE).  I’ve been the Vice President since my election in 2011, with Sanjay Limaye (University of Madison Wisconsin) as the President.  After four years I’ve decided to step down due to other commitments, but I wanted to record here my understanding of how all of these Councils, Unions, Associations and Commissions are organised.  To a newcomer, all the acronyms can be mind-boggling.  The next meeting in 2017 is known as the IAGA-IAMAS-IAPSO meeting, for example, which doesn’t tell you very much!

I certainly like the idea of these international unions and associations - these meetings are among the most diverse that I’ve ever attended, with people from all over the world attending.  So collaborations are clearly being fostered, but in the planetary community, straddling both the astronomical communities and the geophysical communities, we’re swamped with a ridiculously high number of meetings.  On a continental level there’s AGU (American Geophysical Union), AAS (American Astronomical Society) and DPS (Division of Planetary Sciences) meetings in the US; EGU (European Geophysical Union) and EPSC (European Planetary Sciences Congress) in Europe; AOGS (Asia-Oceana Geophysical Society) in Asia, and many more meetings at a national level.  Then there are ‘international’ meetings like COSPAR (Committee for Space Research, https://cosparhq.cnes.fr/), which is actually also a part of the International Council for Science (ICS…. and the acronym forest grows thicker), and newcomers like ExoClimes and the Chapman meetings…. the list grows every year, and I sometimes groan when new meetings are announced.

All in all, you never find the whole planetary community at one single meeting.  Each meeting has it’s own problems (too many parallel sessions, expensive locations, etc), and although DPS and EPSC are my personal favourites, it’s hard to keep up with the constant calls for abstracts. Even harder when dealing with funding councils who don’t always recognise that travel is essential for collaboration and ‘selling’ your science!  One look at the gargantuan multi-page tables of acronyms that made up the IUGG conference program confirmed that I’d made the right decision.  For me, the IUGG meeting was a good example of conference overload, with only a few tens of planetary scientists attending, despite the great opportunity to meet with our Earth science colleagues.  Hopefully the 2017 meeting can be made more inclusive to attract a wider audience.

Sunday, 8 March 2015

The Atacama Large Millimetre/Sub-Millimetre Array (ALMA)

Our flight to northern Chile and stay in San Pedro de Atacama was designed so we could acclimatise to the high altitude and arid conditions of the high desert before visiting the radio observatory at 5050 m on the Atacama plateau.  ALMA is the world’s most sophisticated observatory at these wavelengths, a truly collaborative project between Europe, Japan, America and Chile.  It works by having fifty 12-m antennae (the Main Array) with variable separations in between.  The different baselines allow you to take a Fourier Transform of the sky, correlating the signals from each antenna to provide a spatial resolution far superior to what you can achieve from a single dish in isolation.  The sensitivity to a particular spatial scale depends on the length of the baseline.  Short baseline configurations (150-m) provide access to large spatial scales; long baselines (up to 15 km) provide access to the smallest spatial scales. Twelve additional 7-m antennae (the Compact Array) provide very short baselines for the largest spatial scales.

Within each antenna is a series of receivers, or bands, which determine what wavelengths can be observed.  At the moment bands 3-9 are available to users, providing wavelengths from 420 µm to 3.6 mm (84-720 GHz).  This should extend up the 950 GHz when band 10 is offered, and maybe down to 30 GHz with future receiver development.  Measurements in these spectral bands, at a variety of spectral resolutions, are then fed by cables to the main correlator building a few metres away from the antennae, using the Fourier Transform to assemble an image of the sky with unprecedented spatial resolution.


The ALMA site offers the best observing conditions in Chilean winter (July to November), so the more challenging configurations are used then.  In February the conditions are usually hazardous with extreme snowfall, meaning that the antennae must be oriented so that snow does not accumulate inside the dishes.  Conditions below the snow line can be so wet that flash flooding can destroy the access roads.  Thankfully, by the time of our visit in March, conditions were cold and clear again and excellent for some astronomy tourism.

Extreme Tourism at 5 km 


On Saturday morning we met a bus at 7am for the drive out to the OSF (Observer Support Facility) at an altitude of 2500m.  The sun was rising over the volcano to the east as we drove the dirt road to the facility, a cluster of buildings featuring the main control room and data banks, in addition to the hangers and workspaces of the contractors from Japan, the US and Europe responsible for constructing and delivering the 66 antennae (now empty as their work is done).  Construction was still taking place for a permanent visitor quarters, with temporary buildings housing the astronomers.  We had to each undergo a compulsory medical exam (blood pressure and O2 levels) and safety video, being supplied with small oxygen canisters to use should we feel dizzy at high altitude.  This is a serious medical screening - one of our number didn’t pass and had to remain at the OSF.

We ascended the switch-backed road through the mountains, watching as the dry slopes gave way to some green vegetation and cacti, allowing the grazing donkeys and llama (vicuna) to survive despite the seemingly hostile conditions.  The landscape was not as volcanic or young as that on Mauna Kea, this is a more ancient geology.  We all started to feel lightheaded, but cheered as we passed the 4200-m mark (the height of the Mauna Kea observatories).  For many of us, this marked the highest point we’ve ever been to in our lives.  As we crossed the mountain pass, the plateau opened up before us and the ALMA array came into view.  A small Japanese observatory could be seen on one of the high peaks, which must be one of the highest manned observatories in the world.

We had about half an hour to wander amongst the antennae, which was in a compact configuration after the February snows and undergoing engineering work to prepare for more science.  Eric Villard served as an excellent tour guide, showing the differences between the US and European antennae designs.  As we watched, one of the antennae rotated around silently, controlled by some unseen operator down at the OSF.  The thin air (0.5 bar) and lack of O2 at 5050 metres above sea level does strange things to the brain, an almost drunken experience as we posed for photos with the array in the background.  All of us took occasional puffs from the oxygen canisters if we felt any dizziness, but thankfully I didn’t experience any of the headaches or nausea sometimes associated with high altitude.

We then went inside the correlator building, seeing the banks and banks of computers and hard drives required to bring together the signals from each of the individual antennae.  Then it was time to begin our 45 minute descent back to the OSF for lunch and then on to Calama, drinking in the thicker atmosphere and feeling tired.  It had been a tremendous experience, not only because I now know more about the challenge of radio interferometry for astronomy, but also because of the extreme environment we’d been lucky enough to visit.  Very few humans get this opportunity, so I’m extremely grateful to ESO and the organisers of #planets2015 for the chance!

Friday, 6 March 2015

San Pedro de Atacama

The planetary science workshop ended on Thursday evening, but eighteen of us stayed on in Chile with the opportunity to visit the Atacama Large Millimetre/Sub-Millimetre array (ALMA), high in the Atacama desert in northern Chile.  This was a chance not to be missed, both for the otherworldly environment and the prospect of glimpsing the worlds most sophisticated radio observatory.

We departed Santiago for the two hour flight to Calama, cruising to the west of the Andes and passing the tallest peak in the whole of South America (Aconcagua), 7000 m high and in neighbouring Argentina.  The landscape below was dry and desolate, punctuated by extensive mining works for copper and lithium (apparently Chile is one of the largest global exporters of lithium, making money out of its use in electronics all over the world).  The Atacama is the world’s driest non-polar desert, with some rain gauges having never received any rain, period.  And you could really tell from the air.  Calama itself was a dust bowl, and the rich salt lakes covered the land right up to the mountains (extinct and ancient volcanoes).

A 90-minute bus took us from Calama to San Pedro de Atacama, a small town grown around an oasis in the desert.  We passed through the study Valle de la Luna, with sedimentary rocks thrust and turned on their side to produce a vast red canyon of jutting rock formations.  San Pedro was a really striking experience, as every building was made of the red-coloured adobe, including our hotel the Casa de Don Thomas.  The streets were largely unpaved and prone to dusty breezes flowing through, stray (but not aggressive) dogs roamed everywhere, and waterways criss-crossed the town for use in irrigation.  The village had a central square, featuring an adobe church that was undergoing renovation, a museum containing archaeological remains of the Chilean peoples who first lived here, and a relaxed bar with tables spilling into the square.  There’s one long main street, featuring endless small restaurants, souvenir shops and excursion organisers (from here tourists can visit a geyser field, salt lakes, flamingo reserves, or go sand boarding).

Sadly I had no time to enjoy the resort, only having a couple of hours to stroll the main street and dine in the Adobe restaurant.  Others stayed on for a few extra days following our trip to ALMA, but for me it was time to leave Chile behind.  I returned to Santiago on Saturday night for a brief stay in an airport hotel, then an early morning flight back to London via Sao Paolo.  Incidentally, the 4-hour stop in Sao Paolo on the Tropic of Capricorn was my first ever trip to Brazil!  One day I’ll have to come back….

Thursday, 5 March 2015

ESO Planetary Sciences Workshop 2015

The purpose of my visit to Santiago this spring was to present an invited talk at the ESO “Planets 2015” workshop, known as a “Joint Venture in Planetary Science” between space-based and ground-based observatories.  Organised by Eric Villard (ESO and ALMA) and Olivier Witasse (ESA, and the new project scientist for JUICE), this meeting brought around 80 planetary scientists together for four days in the ESO Vitacura office.  It was a wonderful opportunity to meet people and forge new collaborations, and certainly one of the best meetings I’ve been to in a long time.  Several of us were live-tweeting the meeting, so the highlights can be found there, or via this link on storify.

Science Sessions

Following a keynote talk by Mike Mumma from Goddard Center for Astrobiology, the days were subdivided into science sessions and facility sessions, punctuated by healthy coffee breaks and lunch sessions sat in the gardens surrounding the ESO office.  Monday covered giant planets, where I delivered an overview talk on synergistic studies of dynamics, chemistry and origins from spacecraft and telescopes (I’ll try to summarise that at some point), Imke de Pater revealed gorgeous VLA images of Jupiter; Gordy Bjoraker showed high-resolution 5-µm spectra of Jupiter and Saturn; and Ted Kostiuk gave an overview of atmosphere-auroral interconnections via infrared spectroscopy.  Tuesday’s science session covered terrestrial planet atmospheres (including a Doppler velocimetry technique to measure winds using visible spectroscopy), focussing on Venus and Mars, but with some fascinating ALMA results on Titan (Cordiner) and Io (Moulet), and Katherine de Kleer’s long-term program to monitor Io’s volcanic activity in the L and M band (3-5 µm) using Keck and Gemini.


On Wednesday we venerated into the realm of asteroids, TNOs and comets, including radar observations of asteroids where Benner produced 3-D printed versions of asteroid Bennu (the destination for the OSIRIS-REx mission, due to launch in the next couple of years) showing an equatorial bulge and distinct ‘boulder’ on the surface.  We heard about the jovian trojans and hildas, asteroid families that I know very little about; the discoveries of rings around the centaurs (Chariklo and Chiron); and the prospects for detailed studies of Trans-Neptunian objects.  I learned that many of the Kuiper Belt objects featured small satellites, whose names were completely new to me.  Finally, on Thursday we ventured briefly into exoplanets and planetary formation.  The science sessions had covered a very wide range, and I felt I learned the most from the review/overview presentations rather than the more detailed science talks.  If this meeting were to happen again, a stronger emphasis on review and forward thinking, rather than focussing on your own research, might be the way to go.

Facility Sessions

In contrast, I got a lot more out of the four facility sessions.  As we were sat listening to the presentations on the various observatories, I could see many people in the audience thinking of new ways to study their fields, me included.  Monday afternoon served to pique my curiosity about ALMA, as Eric Villard presented the capabilities of ALMA for planetary science (more on that in a later blog post).  We heard talks on:



  •    The Mauna Kea sub-millimetre valley (SMA, JCMT and CSO) by Mark Gurwell; 
  •    Eliot Young reviewed NASA’s ideas for balloon-borne planetary observatories;
  •    The US NRAO (National Radio Astronomy Observatory) facilities, including the VLA, VLBA and Green Bank Telescope (Butler);
  •    The SOFIA observatory and its instrument suite (Reach);
  •    Ground-based support for Cassini and Juno (Orton);
  •    Use of the deep space network for both telemetry and science via radio link (Lasio);
  •    Instrumentation roadmaps and plans for the Paranal observatory (VLT) in contrast to Keck and Gemini (Dumas);
  •    Plans for the NASA Infrared Telescope Facility (Tokunaga);
  •    The capabilities of the Large Binocular Telescope and Interferometer (LBTI) for high angular resolution studies (Conrad);
  •    IRAM for millimetre studies (Boissier);
  •    The prospects for the James Webb Space Telescope (JWST) for solar system science (Stansberry).


Having experts in these facilities in the same room as the science users proved to be an excellent idea. I had so many useful discussions over coffee and lunch that my to-do list is now enormous.  ALMA, although heavily oversubscribed, is particularly exciting and it would be great to use it for giant planet science.  I got to talk to the instrument scientists in charge of the VISIR renovation and recommissioning (a work-horse of mine for infrared imaging and spectroscopy) and hopefully instilled an excitement for looking at Jupiter and Saturn soon (time awarded in the next semester).  I discussed our SOFIA/FORCAST data on Jupiter with SOFIA specialists, which we’ll use to study deep circulations.  I met with Japanese colleagues working on Subaru/COMICS Saturn imaging (which I actually acquired, along with Glenn Orton, from the summit of Mauna Kea in January 2008), investigating the changing brightness of Saturn’s rings as a function of season.  I met others working on VLT/SPHERE observations and struggling (as I am) with data reduction.  I caught up with a colleague working on exoplanet observations (who just happened to be in Santiago on his way to the VLT), and with colleagues working on Cassini/CIRS, and had lengthy discussions about organisation for ground-based supporting observations for the Juno mission.  On that topic, one of my first tasks when I get back to Oxford is to draft a white paper to try to convince observatories to support this mission.

The last day of the meeting featured a talk from Will Grundy on the New Horizons mission, particularly the heroic ground-based efforts from John Spencer and other to identify a suitable KBO target for a second flyby after Pluto.  Two candidates were found (PT1 and PT3), ultimately using lots of Hubble time.  But the idea that the Pluto encounter is already underway, and that this whole system will be gradually revealed in glorious detail over the next few months, is breathtaking.  History in the making, and a great way to end the meeting.