Friday 17 November 2017


This month I was contacted by a reporter from 'Space Boffins' to ask some questions about Triton, the captured Kuiper Belt Object orbiting Neptune.  Here are my replies....

How much of a surprise was the data from Triton, when it was first seen by Voyager 2?
By the time it reached Neptune, the Voyager missions had already cemented themselves as the most important interplanetary missions of all time.  But Uranus had been somewhat of a disappointment - like Titan before it, the skies of Uranus appeared bland and without the dramatic atmospheric activity shown by Jupiter and Saturn.  In the summer of 1989, Neptune went from a mere point of light, an astronomical object, to being a fully-resolved world in its own right.  What’s more, the icy moons of Saturn and Uranus, though geologically interesting, were simply cratered balls of ice and rock.  Who would’ve believed Triton would be any different?  When those first images came down, the onlookers at JPL were surprised (remember, this is way before 24-hour rolling news or Twitter) - a distant moon of a distant world appeared geolocically active, with geysers erupting from the young, frozen ice and nitrogen surface of ridges, plains, depressions and fissures.  Far from a geologically-dead world, this was an active environment producing its own tenuous atmosphere, and is a good ambassador for the more distant (and harder to reach) objects from the Kuiper Belt.

To what extent is the moon an oddity?
It’s that sense that Triton is an interloper in the Neptune system, that it shouldn’t be there, but that it’s a representative of the unusual worlds even further from the Sun.  We’ve seen so tantalisingly little of it compared to the satellites of the giant planets, and after the Pluto flyby revealed the extreme and unexpected geological activity of that distant world, a return trip to Triton - our most accessible example of a captured KBO - has to be on the cards.

Surprising that it’s not inert but has geysers (activity at such a distance from the Sun)?
Triton’s surface certainly shows all the signs of icy volcanism, which will have shaped and resurfaced the moon over the millennia.  Where the internal energy comes from to power that activity is unclear - tidal stresses, like those that keep Europa’s internal oceans liquid and Io as the most volcanically active place in the solar system, seem to be insufficient.  It’s interesting that the N2 geysers all appeared to occur where the sunlight falling on Triton was the strongest, so the action of solar heating destabilising the surface layers must play a role in the geysers, which are distinct from the larger scale evidence of cryovolcanism.

How frustrating is it that you’ve got such little data on it?
Excruciating!  A whole world just waiting there for humankind to discover, map, and understand (the same is true of much of the Uranian and Neptunian systems).  But thank heavens that NASA had the ambition and tools to get us what little data we have - I hope that ESA and NASA, working together, will one day build on the legacy of the Voyagers.

What stage are missions in development to visit Neptune and its moons?
For the past decade or so, there have been very positive signs that the agencies on both sides of the Atlantic are taking the ice giants very seriously.  Back in 2009, our community wrote a series of ‘white papers’ proposing the myriad exciting reasons to mount a mission to the ice giants as a natural successor to the outrageously successful Cassini mission.  Subsequently, an ice giant flagship mission was recommended by the US decadal survey as their 3rd priority (after another Mars rover in 2020 and the Europa Clipper mission, currently in its implementation phase).  At the same time, European scientists began to throw around an idea for a Uranus mission called Uranus Pathfinder (led by UK scientists) - this was submitted to ESA’s call for medium class missions twice, and also as a ‘large class’ mission to follow JUICE (the Jupiter Icy Moons Explorer, also in the implementation phase).  None of these mission concepts proceeded to the crucial next step (a formal study by ESA), but they were deemed sufficiently exciting that the panels urged us to keep fighting the good fight.  The acknowledgement was that the time of the ice giants would come, eventually.

Then, last year, NASA and ESA worked jointly on a ‘Science Definition Team’ for a future ice giant mission, evaluating the pros and cons (both scientifically, financially, and technologically).  They looked at flyby spacecraft, orbiters, atmospheric probes, and even dual spacecraft, one for each of the ice giants.  An orbiter, along with a probe, is probably the most natural choice - think of a long-lived Cassini-like mission, complete with a 21st century instrument complement, executing multiple flybys of Triton to map it surface geology and chemistry, the tenuous atmosphere and geological activity, and maybe its subsurface using ice penetrating radar, magnetometers and gravity measurements.  The extensive report was presented to both NASA and ESA (and the community at large), with the recommendation being for further study and refinement.  But I hope that this will influence the next US decadal survey to put an ice giant mission right at the top of the list, with international partnership as a key enabling element (maybe a NASA orbiter with an ESA-provided probe)?

Could there be life there?
Everywhere we look in the outer solar system, we find surprises.  Geologically dead?  No.  Solid balls of ice?  No.  Inexplicable geological activity?  Yes.  One of the common themes emerging is that these icy worlds possess subsurface oceans - hidden, dark, abyssal seas that could host the right conditions to be labelled ‘habitable’.  That is, we need to ensure that the water, chemicals, and source of energy are present at the same location and for long aeons of time.  Europa Clipper and JUICE will answer that question in the jovian system.  But to address this for an ice giant satellite needs a dedicated mission.

Any chance of landing on Neptune or Triton?
Uranus and Neptune are both perfect targets for atmospheric entry probes, descending under parachute into the skies of the ice giant to sniff out the chemical species that are present.  With no atmosphere to slow it down, a landing on one of their moons (Triton included) would be a tremendous challenge, not least because you need to take enough fuel with you to slow yourself down.  But never say never, and if, after a first proper reconnaissance of an ice giant system we decide that we simply must go back and land, then I’m sure we’ll be inventive enough to find a way.

Tuesday 24 October 2017

New Paper: Disruption of Saturn's Equatorial Oscillation

A decade ago, when Cassini was still in its prime mission at Saturn, thermal observations from the Composite Infrared Spectrometer revealed that Saturn’s equatorial atmosphere exhibited an alternating pattern of temperatures and winds that bore a striking resemblance to similar features on Earth and Jupiter.  Immediately this suggested some shared atmospheric traits between Earth and the giant planets, despite the considerable differences in the environments of the terrestrial and gas giant worlds.  Equatorial oscillations may be a fundamental feature of planetary atmospheres, a regular heartbeat that teaches us about the forces shaping the tropical stratosphere - namely atmospheric waves launched upwards by convective plumes at deeper levels.

When we started this particular project, the intention was to track the descending pattern over the entire length of the Cassini mission, through a full cycle.  We’d measure the descent rates and study the influence of the stratospheric pattern on the equatorial winds.  It was then a considerable surprise to see that the pattern was eradicated in 2011-2013, and the dates were a smoking gun for the cause - waves emanating from the Great Northern Storm, tens of thousands of kilometres away.

This connection between seemingly-unrelated patterns is well-known on Earth - for example, the influence of the El Nino Southern Oscillation on meteorological patterns across the globe.  Earth is a highly coupled system in delicate balance, and these new results suggest that the same is true of Saturn.  Indeed, in 2016 the Earth’s QBO exhibited a similar disruption, that was shown at the time to be unprecedented in the 60-year record of QBO observations.  The authors of that study suggested a source of waves in Earth’s northern hemisphere disrupting the regular pattern, and we were seeing exactly the same thing on Saturn.  Once again, the atmospheres of Earth and Saturn were shown to have similarities despite the vast differences between these two worlds.

This work helps us to understand the common forces driving the tropical atmospheres on multiple planets, and shows that these atmospheres are highly coupled and intricate systems that are susceptible to perturbations by grand meteorological events, like the Great Northern Storm of 2011.

Cassini carried an instrument called the Composite Infrared Spectrometer (CIRS), for which I’m a co-investigator.  This instrument measures thermal infrared spectra from 7 microns out to 1000 microns, and by modelling these spectra as a function of latitude and time, we can derive the oscillating pattern of temperatures and winds.  If you look at the four movies here (particularly the second one):
…you can see the shifting patterns.

Although Cassini has sadly come to an end, we will be continuing to track this oscillatory pattern and the eruptions of storm activity using Earth-based assets.  The University of Leicester is involved in a programme of observations from the VLT, Subaru and IRTF observatories to track Saturn’s seasonal evolution over long spans of time.  Furthermore, we will be employing the James Webb Space Telescope (JWST) when it launches in 2019 to catch another glimpse of Saturn’s tropical atmosphere, as part of a ERC-funded programme called GIANTCLIMES.

Full details of the article, published in Nature Astronomy, can be found here:

Thursday 28 September 2017

Farewell, Cassini.

The full listing of contents can be found here:

Thursday 14 September 2017

Cassini EOM

How are you feeling today?

This has been a bittersweet week, watching as my Cassini colleagues gather for the final time to watch the end of this 20-year journey.  This heroic spacecraft has done everything we’ve ever asked of it, even fighting with it’s last moments to deliver new scientific insights back to Earth.  So although I’m sad that Cassini’s exploration will now be a part of the history books,  I think we can be proud of everything that this mission has accomplished.  It just shows what wonders can be achieved when 27 nations work together.

Cassini CIRS team members at their last team meeting with a working spacecraft - June 2017

What will you be looking for in the last set of images to come down from the spacecraft - especially the final one of the spot where it will plunge into the cloud tops?

Those last final looks around the Saturn system will be heart-wrenching, as our last chance to witness new photos of these environments for a generation or more.  Combined with all our recent close encounters in 2017, the resolution of the last images of Saturn’s individual swirling clouds will be revealing the meteorological complexity underlying the usual serene appearance.  But Cassini will meet its fate high in the atmosphere, so the cloud-top meteorology might have little impact on what Cassini is able to measure in its final moments.

And CIRS is going to be on until the bitter end, right? What sorts of insights are you hoping to squeeze out of those final minutes of data?

Oh yes - along with some of the other instruments, CIRS will be fighting to deliver science until the very end of the journey.  These won’t be your typical data - CIRS is used to measuring spectra slowly and returning them to Earth hours later.  In real time, we’ll be getting housekeeping data (i.e., the instrument temperatures, voltages, etc.) and looking for any spikes in our measured interferograms, particularly as the CIRS field of view sweeps over the rings in the last 20 minutes or so.  We expect measurable heating about 25 minutes before loss of signal.  But, as we’ve never done this before, we’re waiting for (and expecting!) surprises!

At one of our team meetings, it was noted that CIRS’ scan platform has travelled 106 miles in tiny 2-cm chunks to assemble its interferograms - in all, more than 170 million interferograms have been acquired.  That legacy will keep scientists going for decades.

Friday 8 September 2017

Cassini's Final Moments

After almost twenty years in space, the Cassini spacecraft is now just seven days away from its final encounter with the giant planet, ending humankind's first detailed exploration of the ringed planet.  Cassini's Grand Finale is the ambitious culmination of a mission by a nuclear-powered robotic explorer that has travelled a total of 4.9 billion miles, completing 294 orbits of Saturn, with 360 engine burns, 2.5 million commands executed and 635GB of science data collected.  That science data, which includes half a million images, has been used to generate more than 4000 papers in scientific journals, and has started the careers of many young scientists, myself included.  But to me, the most important credential that this mission can be proud of is its international nature - 27 nations, including the UK, were involved in this fantastic mission.  Cassini-Huygens will truly be the benchmark against which all future missions are compared.

Cassini's vital statistics.

The Grand Finale started on April 22nd with the 126th close flyby of Titan, which initiated a series of 22 close polar orbits around the giant planet.  The first ring plane crossing, bringing Cassini between Saturn and its innermost rings, occurred on April 26th.  The spacecraft was travelling at roughly 70,000 mph relative to the cloud tops.  Thankfully, the dust that we suspected might be present in this unexplored region was absent, so that spacecraft constraints could be relaxed just a little.  As Cassini continued to loop around Saturn once every 6 days, the final five orbits actually dipped the spacecraft down into the tenuous upper atmosphere, allowing the mass spectrometer (INMS) to directly sample the composition of the atmosphere.  Here too, Cassini was lucky - although contingency plans had been in place should anything go wrong, no rocket firings to maintain attitude control were actually required, and the spacecraft emerged from these encounters unscathed.

The Final Week

And so we arrive at Cassini's final week before its plunge into the Saturnian clouds on September 15th.  On Saturday September 9th, at 01:09BST (subtract one from all my times to get them in UT),  Cassini will execute its final dive between Saturn and the rings, skimming just 1680 km above the clouds.  Then on Monday September 11th at 20:04BST, the final distant encounter with Titan (the 127th flyby at 120,000 km distance, known as the "goodbye kiss") will slow the spacecraft sufficiently that Isaac Newton and the force of gravity will never allow Cassini to escape its final orbit.

On Wednesday and Thursday September 13th-14th, Cassini will be assembling its final picture show, including colour mosaics of Saturn and its rings, a movie of Enceladus setting behind the northern limb of Saturn, and observations of tiny moonlets within the ring system.  Linda Spilker, Cassini's project scientist, described these bittersweet images beautifully as "like taking one last look around your home before you move out."  The final image will be taken at 20:58BST on Thursday September 14th, before the spacecraft is reconfigured for atmospheric entry on Thursday night.

The Final Moments

Instruments working during Cassini's final moments at Saturn.
On Friday September 15th, at 06:08BST, Cassini will cross the orbit of Enceladus one final time.  Two hours later, the spacecraft will roll to ensure that the mass spectrometer is pointed in the direction of travel, able to access the oncoming gases during the plunge.  Rather than storing science data onboard, Cassini will begin transmitting in real time (3.4 kbps) for the last 3.5 hours, with its high-gain antenna pointed directly at Earth.  Eight of Cassini's 12 instruments will be on and taking data - the mass spectrometer (INMS), magnetosphere and plasma science instruments, the radio science subsystem, and the infrared and ultraviolet spectrometers (CIRS included).

At 11:31BST the fight begins, as the spacecraft begins to enter the atmosphere at about 1190 miles (1920 km) above the cloud tops and needs to use its thruster to battle against the torques on the spacecraft.  The thrusters will ramp up to 100% of their capacity in a matter of seconds as the probe falls through 250 miles (to around 940 miles above the clouds), where the torques are expected to overcome Cassini's ability to correct its attitude.  At this point, we expect Cassini to begin to tumble around several axes, such that the high gain antenna is no longer locked on Earth.  The final photons will have been transmitted back to the Deep Space Network of radio telescopes on Earth at 11:32BST.  Cassini will continue to fight, its fault-protection systems trying in vain to stabilise the spacecraft, but within seconds the high loads on the spacecraft will start to destroy structural components.  The spacecraft will break apart, burning up like a meteor and melting, the individual materials dissociating so that the debris forever becomes a part of Saturn.

Meanwhile, those last photons from a ghost spacecraft will take 83 minutes to cross the 1.5 billion kilometres to Earth, where the final loss of signal is expected at around 12:55BST.   At that moment, I expect the silence at JPL, and all the other laboratories that have been part of this grand mission, to be deafening.


At a Cassini CIRS team meeting in June, I learned that the instrument operations team had uplinked a very special sequence of four tables to the spacecraft, to be uploaded to the instrument memory during that final plunge.  The four tables contained a message from all of the 282 scientists and engineers that had been involved in CIRS between 1990 and 2017.  It's an incredible privilege to be on this list, and to know that Cassini will be thinking of home as it completes its final journey!

The names in Cassini/CIRS memory in the final seconds.

Finally, Ralph Lorenz has a nice article on arxiv about whether we'll be able to see this event from Earth

My Cassini Experience

In June 2017 I was interviewed about my feelings on the demise of the Cassini spacecraft - here are some personal reflections on my time with Cassini.  The quotes were picked up in JoAnna Wendel's excellent piece on EOS.

How did you get into planetary science?

I’d been interested in space exploration since childhood, watching with awe as the space shuttle completed its missions and Hubble delivered stunning views of the universe.  But when I went off to university in 2000, solar system studies weren’t really on my radar:  I was set on studying physics and maths, and all my physicist friends were getting excited about cosmology and particle physics.  But the more I looked into those fields, I realised I wanted to study something more tangible - something closer to home, something we could see with our own eyes, something that we might one day be able to reach out and touch.  After a course in geophysics at Cambridge, I started to look into planetary science opportunities at PhD in 2003.

How did you get involved in Cassini research? When was that?

It turned out to be the perfect moment to start looking at PhD opportunities in planetary science in the UK.  Cassini was just months away from Saturn Orbit Insertion, and the UK teams involved in the mission were advertising a number of opportunities.  I was interviewed for positions to study magnetic fields and plasma science, but I ultimately settled on a PhD in planetary atmospheres at the University of Oxford.  Oxford had provided hardware (focal plane assemblies and a cooler) to the Composite Infrared Spectrometer (CIRS) instrument, led by Goddard Spaceflight Center.  CIRS measures thermal radiation from planetary atmospheres, rings and satellite surfaces, and the Oxford team were looking for PhD candidates to analyse Saturn and Titan observations from those preliminary Cassini orbits.  I was offered the place in 2004, completed my degree in the summer and waited with baited breath to see if Cassini would survive that first ring-plane crossing.  I then arrived in Oxford in October 2004, ready to roll up my sleeves and start analysing CIRS data - that formed the basis of my doctoral thesis in 2007, Saturn’s Atmosphere:  Structure and Composition from Cassini/CIRS.  It’s safe to say that I wouldn’t be where I am today if not for that opportunity to work with the Cassini team from the start of the Saturn mission.

Are you still working with Cassini data, and if so, what mysteries still exist about Saturn, its moons, etc? 

Absolutely!  CIRS has now been observing Saturn for 13 years, almost spanning from solstice to solstice, providing us with the best chance of characterising a seasonal giant planet.  I’m still tracking the evolution of temperature, cloud and compositional changes arising from both slow seasonal variations and short-term outbreaks of storm activity on the gas giant.  Cassini has revealed Saturn’s atmosphere to be deeply interconnected, with activity in vastly separated regions having substantial consequences elsewhere - for example, the deep roiling tropospheric storm of 2011 had substantial side-effects in the stratosphere and possibly even the ionosphere.  We’re still trying to understand what connects different regions of Saturn’s atmosphere, and what deep processes, hidden well below the clouds, are responsible for the timescales and violence of the massive outbreaks that we see.

Will you be able to continue using Cassini data after the mission ends?

We’ll be trying to provide a complete 13-year temperature, composition and aerosol dataset that spans the entire mission, as a resource for future researchers studying atmospheric processes on giant planets.  So I’m sure I’ll be delving into the CIRS dataset for many years to come.

How has Cassini changed the way that scientists understand your particular research/field?

I think I answered this one above, when I spoke about Saturn’s atmosphere being deeply interconnected.  But beyond that, I think we’ve started to show that ideas inherited from the study of terrestrial meteorology and climatology (jet streams, Hadley circulations, moist convective storms and lightning, polar vortices, equatorial oscillations) can be applied to gas giant atmospheres, despite the vastly different environmental conditions.  It’s showing that a number of atmospheric processes are commonplace across vastly different worlds.

What kinds of feelings do you have now that Cassini is ending?

Pride in what we’ve accomplished; gratitude that I was offered a chance to become involved; and sadness that a team I’ve worked with for 13 years will now be moving on to pastures new.  Whenever I watch the CGI movie of Cassini’s final demise, it’s hard not to feel moved.  If you forget all the exciting science, Cassini is an incredible testament to spacecraft engineering and operations, having worked so well for so long.  Cassini is the best example of US-European collaboration that i know of, and it’s hard to imagine that we’ll ever have another spacecraft like it.  That said, just think what we might accomplish with Cassini-style exploration of the next two great outposts in our solar system:  Uranus and Neptune?  I hope that I’ll be able to offer new PhD candidates the opportunity to study data from robotic explorers of the ice giants, some day!

Wednesday 23 August 2017

Saturn from Cassini: Image Gallery

One of the most common requests I'm getting at the moment is to provide some of my favourite Saturn imagery from Cassini, so I've assembled my top selection over on Pinterest.  These come from various sources (APOD, NASA's Photojournal), and by clicking on the links you'll be able to go to higher-resolution versions of the images.  Here's a screenshot, but it's best to pop over and take a look!

Monday 10 July 2017

Ten Facts about the Great Red Spot

In honour of Juno's close encounter with Jupiter's Great Red Spot (GRS) on July 11th 2017, here are some quick facts about the Solar System's most famous storm system:

Comparing Hubble and VLT thermal observations of the
Great Red Spot in 2006.

  1. The Great Red Spot is a very long-lived spinning vortex: hand drawings show the GRS back in the Victorian era, but it might have persisted for even longer than that - even Robert Hooke's and Giovanni Cassini's 17th century observations suggest a feature at this particular latitude, so it might have been around for almost four centuries.
  2. The Great Red Spot appears to roll like a ball-bearing between two of Jupiter's colourful cloud bands:  the brown South Equatorial Belt and the white South Tropical Zone.  The westward jet that separates these two bands is deflected northwards around the vortex making the storm rotate anticlockwise, meeting the eastward equatorial jet and causing lots of turbulent, chaotic structures to the northwest of the storm.
  3. If you were on a balloon at the edge of the swirling storm, you'd be blown around the vortex in about 3.5 days.  Of course, you'd need to find a way to be lighter than hydrogen and helium to float, but the anticlockwise winds would mean that you'd be blown around the swirling maelstrom - what a view that would be!
  4. The Great Red Spot has been shrinking:  We've known this for many years, as the size measured by Earth-based and space-based observers (including the Hubble Space Telescope) has been tracked over time.  Voyager measured a width of 25000 km in 1979, but that's now decreased to as small as 15000 km.  But the shrinking is not continuous - it went through a period of rapid shrinkage in 2012-2014, but has now appeared to stabilise at the new smaller size.  Who knows whether we'll ever witness the death of the spot?
  5. The Great Red Spot consumes smaller storms:  smaller storm plumes, vortices and storm clusters moving along Jupiter's jet streams can be seen being engulfed by the storm.  Maybe this provides the extra energy and angular momentum needed to sustain this swirling anticyclone?
  6. The Great Red Spot is cold:  At the cloud-tops the Great Red Spot is cold because air is rising within the vortex, expanding and cooling down.  This cooling causes gases to condense, creating the thick cloud cover high over the GRS.
  7. The Great Red Spot has a warm cyclonic heart:  Thermal infrared images show a warm core to the cold vortex, and this warm core coincides with the deepest red cloud colours, and possibly a stagnation of the winds.  Is this the core of the vortex?
  8. The Great Red Spot is not quite the same as a hurricane:  There's no ocean beneath to sustain the energy of the GRS, and no one truly knows how far down the GRS extends into the deep atmosphere (is it deep or shallow)?  That's one of the things that Juno could show us.
  9. We still don't know why it's red:  There's no distinct spectral signature for the aerosols causing the red colouration, but we think it is related to sunlight breaking down the chemical bonds of materials dredged up by the upwelling in the storm.  These chemically-altered species might contain sulphur and phosphorus, which could lead to the red colours.  
  10. Juno will be closer to the Great Red Spot than ever before on July 11th 2017:  Juno is due to fly about 9000 km above the centre of the Great Red Spot (GRS) on Monday night, about 12 minutes after its closest approach to the planet on July 11 at 01:55 UT. 

Friday 30 June 2017

Earth-based observations prepare Juno for the Great Red Spot Encounter

In just a few days time, on July 11th 2017, NASA's Juno spacecraft will perform the closest-ever views of the swirling maelstrom known as Jupiter's Great Red Spot.  It was always hoped that the pre-planned polar orbit and close perijove passes would take the spacecraft over the storm, but the slow and somewhat unpredictable westward motion of the gigantic vortex meant that a little luck would be required.  That luck comes in on Perijove 7, and we'll be rewarded by breathtaking views - so close that the vortex will stretch from jovian horizon to jovian horizon.

In preparation for that encounter, myself and others have been collaborating on an Earth-based support campaign, capturing multi-wavelength views of the jovian atmosphere to provide spatial, temporal and spectral context for Juno's close-in encounters.  Today, two of the telescopes we've been using released some of our imagery from May 19th 2017, acquired during Juno's last perijove 6.  These images show the Great Red Spot as it was just a few weeks ago, and prepare us for Juno's close-in views.

Thermal Emission from Jupiter

Both observatories are located on the peak of Mauna Kea on the Big Island of Hawaii.  We have been working with the Subaru Telescope (the National Observatory of Japan) and the Gemini-North telescope.  The COMICS instrument on Subaru provides mid-infrared (7-25 µm) observations that reveal the temperature structure, gaseous composition and cloud opacity within the Great Red Spot.  The Subaru telescope has released an image at 8.8 µm, which primarily senses temperatures and aerosols, showing the planet's white zones as cold and cloudy (i.e., dark) and the brown belts as warm and cloud-free (bright).  The Great Red Spot can also be seen as cold and cloudy, something that we studied at length (using both Subaru data and those from ESO's Very Large Telescope VISIR instrument) in an Icarus paper in 2010.

Jupiter's thermal emission at 8.8 µm obtained by the Subaru/COMICS instrument on May 18th 2017.  A video created from a series of observations with the same settings on January 14th 2017 is also available. Credit:  NAOJ and JPL.

Glenn Orton was the PI of Keck exchange time to use the Subaru facilities, and said this in the press release:  "During our May 2017 observations that provided real-time support for Juno's sixth perijove, we obtained images and spectra of the Great Red Spot and its surroundings.  Our observations showed that the Great Red Spot had a cold and cloudy interior increasing towards it centre, with a periphery that was warmer and clearer.  This implied that winds were upwelling more vigorously towards its centre and subsiding at the periphery.  A region to its northwest was unusually turbulent and chaotic.... this region is where air is heading east towards the GRS and flows around it to the north, where it encounters a stream of air flowing over it from the east."  Crucially, observations of this kind, from the VLT and from Subaru, are capable of resolving 1000-km length scales on Jupiter that are comparable to Juno's microwave experiment, which will sound the deep atmospheric processes underlying those that we can see in this thermal image.

Jupiter in Reflected Sunlight

At shorter wavelengths, the NIRI instrument on the Gemini-North observatory captured the reflected sunlight from the Great Red Spot and its surroundings, as explained in their press release.  These observations required Adaptive Optics, using observations of a nearby satellite to observe and correct for the distortions caused by our own atmosphere.  Orton explains: “Back in May, Gemini zoomed in on intriguing features in and around Jupiter’s Great Red Spot: including a swirling structure on the inside of the spot, a curious hook-like cloud feature on its western side and a lengthy, and a fine-structured wave extending off from its eastern side.”  By observing Jupiter in a variety of different near-infrared wavelengths, which sense differing amounts of methane absorption, we're able to reconstruct the three-dimensional cloud structure within Jupiter's upper troposphere.

A composite colour infrared image of Jupiter reveals haze particles over a range of altitudes, as seen in reflected sunlight. The image was taken using the Gemini North telescope with the Near-InfraRed Imager (NIRI) on May 18, 2017, one day before the Juno mission’s sixth close passage (“perijove”) of the planet.  Credit: Gemini Observatory/AURA/NSF/JPL-Caltech/NASA

Version of the image above labelled by Dr. John Rogers of the British Astronomical Association.

From the Gemini press release:  The colour filters cover wavelengths between 1.69 to 2.275 microns and are sensitive to pressures of 10 millibars to 2 bars. The Great Red Spot (GRS) appears as the brightest (white) region at these wavelengths, which are primarily sensitive to high-altitude clouds and hazes near and above the top of Jupiter’s convective region – revealing that the GRS is one of the highest-altitude features in Jupiter’s atmosphere. The features that appear yellow/orange at Jupiter’s poles arise from the reflection of sunlight from high-altitude hazes that are the products of auroral-related chemistry in the planet’s upper stratosphere.

Narrow spiral streaks that appear to lead into it or out of it from surrounding regions probably represent atmospheric features being stretched by the intense winds within the GRS, such as the hook-like structure on its western edge (left side). Some are being swept off its eastern edge (right side) and into an extensive wave-like flow pattern; and there is even a trace of flow from its north. Other features near the GRS include the dark block and dark oval to the south and the north of the eastern flow pattern, respectively, indicating a lower density of cloud and haze particles in those locations. Both are long-lived cyclonic circulations, rotating clockwise - in the opposite direction as the counterclockwise rotation of the GRS. A prominent wave pattern is evident north of the equator, along with two bright ovals; these are anticyclones that appeared in January. Both the wave pattern and the ovals may be associated with an impressive upsurge in stormy activity that has been observed in these latitudes this year. Another bright anticyclonic oval is seen further north. Juno may pass over these ovals during its July 11 closest approach. High hazes are evident over both polar regions with much spatial structure that has never been seen quite so clearly in ground-based images, with substantial variability in their spatial structure. The central wavelengths and colors assigned to the filters are:1.69 microns (blue), 2.045 microns (cyan), 2.169 microns (green), 2.124 microns (yellow), and 2.275 microns (red).

Jupiter's Deep Glow

Supplementing the two investigations above, a ground-based programme is also under way to observe the deep thermal emission of Jupiter near 5 µm.  We released images from ESO's Very Large Telescope last year, and this programme has continued for each of Juno's perijoves. A parallel Gemini programme headed by Michael Wong of the University of California, Berkeley, used an approach commonly called “lucky imaging” to obtain sharp images of Jupiter at 5 µm. Images obtained with this filter are mainly sensitive to cloud opacity (blocks light) in the pressure range of 0.5 to 3 bar. “These observations trace vertical flows that cannot be measured any other way, illuminating the weather, climate and general circulation in Jupiter’s atmosphere,” notes Wong.

Jupiter glows with thermal (heat) emission at 5 µm, thick clouds block the emission from the deeper atmosphere. The Great Red Spot is visible just below centre. This image, obtained with the Gemini North telescope’s Near-InfraRed Imager (NIRI), was obtained on January 11, 2017, so the relative positions of discrete features have changed with respect to the near-infrared image above.  Credit: Gemini Observatory/AURA/NSF/UC Berkeley 

For more information about the National Astronomical Observatory of Japan's Subaru Telescope, visit:  For more information about the Gemini Observatory, a partnership of the United States, Canada, Brazil, Argentina and Chile, visit:

For the Subaru Image:  Orton (Jet Propulsion Laboratory) and Yasumasa Kasaba (Yohuku University, Japan) led the team, with Takuya Gujiyoshi (Subaru Telescope astronomer) operating the telescope.  Other team members included James Sinclair, Anna Payne (JPL), Joshua Fernandes (California State University, Long Beach), Leigh Fletcher (University of Leicester), Patrick Irwin (University of Oxford), Padma Yanamandra Fisher (Space Science Institute), Takao Sato (JAXA), Davide Grassi (IAPS/INAF), Shohei Aoki (IASB, Belgium), Tomoki Kimura (RIKEN), Chihiro Tao, Takeshi Kuroda (NICT)l Takeshi Sakanoi, Hajime Kita, Hiromu Nakagawa (Tohuku University), Hideo Sagawa (Kyoto Sangyo University) and Joana Bulger (Subaru Telescope).

For the NIRI Image:  Orton leads the observing team for the adaptive-optics imaging and Wong heads the observing team for the thermal imaging. Additional team members include Andrew Stephens (Gemini Observatory); Thomas Momary, James Sinclair (JPL); Kevin Baines (JPL, University of Wisconsin), Michael Wong, Imke de Pater (University of California, Berkeley); Patrick Irwin (University of Oxford); Leigh Fletcher (University of Leicester); Gordon Bjoraker (NASA Goddard Space Flight Center); and John Rogers (British Astronomical Association).

Wednesday 28 June 2017

Saving Cassini - ESA and NASA in 1994

In June 1994, as a result of threatened cuts during Dan Goldin's tenure as NASA administrator, our epic mission to the Saturn system was under extreme threat of cancellation.  The background to these decisions is covered in Michael Meltzer's excellent book, but I'd always heard of the striking letter sent directly to Vice President Al Gore (i.e., bypassing Goldin) from ESA's Director General, Jean-Marie Luton.  I managed to track this letter down in an appendix to a 1998 book from the National Academic Press on U.S.-European Collaboration In Space Science, and it's reproduced here.  Further background can be found in the NASA in the World book.

Letter from the European Space Agency to the Vice President of the United States, June 13, 1994

european space agency

agence spatiale européenne


Paris, 13 JUNE 1994

Jean-Marie Luton
Director General

The Honorable Albert Gore, Jr.
Vice President of the United States
Old Executive Office Building
Washington, DC 20501

Dear Mr. Vice President,

I have recently received a number of disturbing reports that suggest that the continuation of the joint U.S./European CASSINI mission could be threatened by ongoing Congressional deliberations on NASA's FY95 Appropriations Bill.

I am aware that the House version of the Bill, as marked up by the House VA-HUD and Independent Agencies Subcommittee on June 9, retains the necessary funding for NASA's portion of the mission. However, I am also aware that the House Subcommittee's Senate counterpart is faced with a more stringent budget allocation. I am told that the Subcommittee Chair, Senator Mikuiski, has indicated that without an increase in said allocation, termination of a major NASA programme would have to be contemplated, with specific reference being made to the CASSINI mission.

In the field of space science, CASSINI is the most significant planetary mission presently being undertaken by either the European Space Agency (ESA) or NASA, involving the exploration of Saturn, the most complex planet in the solar system and of its Moon, Titan. It is expected to provide at least a ten-fold increase in our knowledge of both bodies as compared to NASA's highly successful Voyager mission.

In making the commitment to participate with the U.S. in 1989, ESA oriented its overall space science programme in order to select this cooperative project, rather than opt for one of a number of purely European alternatives that were proposed at the same time. This decision was taken on the basis of scientific merit and in the belief that the cooperation would be of major benefit to both the U.S. and European scientific communities as well as the international science community in general. Over the past five years, while ESA's Long-Term Space Plan has been forced to undergo a series of significant revisions, driven primarily by our own budget limitations, the Member States have maintained a full commitment to the space science portion of the plan, of which CASSINI is an essential component.

To date, the Member State governments of ESA have committed around $300 Million to our portion of the mission (the Huygens Probe that will descend into the atmosphere of Saturn's Moon Titan, and several elements of the Saturn Orbiter Payload), of which two-thirds have already been spent, and have committed to a further expenditure of around $100 Million to see the mission through to completion. These figures do not include the approximately $100 Million contribution of Italy via a NASA/Italian Space Agency bilateral agreement.

The HUYGENS programme has been in the hardware phase for the past four years, with probe delivery to NASA due to take place in two years time. The hardware integration and testing phase started in early May this year.

The CASSINI mission has generated intense interest in Europe, both within the scientific and engineering community and from the public at large. Approximately 900 European scientists and engineers are working on the programme with more than 30 European institutes and universities involved in the preparation of CASSINI/HUYGENS science.

Europe therefore views any prospect of a unilateral withdrawal from the cooperation on the part of the United States as totally unacceptable. Such an action would call into question the reliability of the U.S. as a partner in any future major scientific and technological cooperation.

I urge the Administration to take all necessary steps to ensure that the U.S. commitment to this important cooperative programme is maintained so that we shall be able to look forward to many more years of fruitful cooperation in the field of space science.


J.M. Luton

Monday 26 June 2017

Wilton Exoplanet Fellowships at Leicester

A recent advertisement to come and join our team in exoplanet science at Leicester!  In particular, if you're interested in the characterisation of exoplanetary atmospheres via spectral inversion techniques, please do get in touch.

Exoplanetary research is one of the most rapidly developing fields in modern science, with the discovery of thousands of worlds beyond the confines of our own Solar System.  Drawing upon the breadth of expertise in the Physics and Astronomy Department of the University of Leicester, the Exoplanet Research Team is involved in a wide-ranging scientific programme at the forefront of this field.

Winton Philanthropies ( have recently announced a number of new exoplanet fellowships to be held at a university within the UK.

We therefore invite applications from young scientists with PhDs (obtained by September 30th, 2017) and no more than 5 years’ postdoctoral experience (exceptions will be made for periods of extended leave), to apply to join the exoplanetary research team at the University of Leicester.

The University of Leicester has 7 academic members of staff (2 of whom hold ERC consolidator grants), 4 postdoctoral researchers and 10 PhD students working in fields related to exoplanetary science. We are one of the founding members of  the Next Generation Transit Survey (NGTS), and are part of the JWST MIRI instrument team. Our expertise includes planet formation and migration, protoplanetary discs and dynamics of planetary systems, the detection and characterisation of exoplanets using photometry, characterisation of exoplanet atmospheres via spectral inversion; and aurora and magnetic fields.

To apply, please send Sarah Casewell ( a pdf by Friday 21 July, containing:

  1. Curriculum Vitae 
  2. 1 page concise research proposal indicating how your research aims complement and extend the existing exoplanetary research at Leicester and identifies one or more suitable academic hosts.
  3. Publication list

Each institution may only submit 2 candidates, and we will invite our selected applicants to make a full proposal at the start of August, with the final submission date of September 1st, 2017. Candidates will not be permitted to participate in multiple applications with different institutions and must be in a position to hold the Fellowship at a UK university.  In October 2017 Winton Philanthropies will announce awardees and the fellowships must commence within six months of the award.

Research topics include:

  • Formation and evolution of exoplanets looking in particular at how protoplanetary discs shape young planetary systems. (contact: Dr Richard Alexander PI of the ERC Consolidator Grant project "Building planetary systems: linking architectures with formation (BuildingPlanS)”).
  • Brown Dwarf observations and theory, in particular irradiated brown dwarfs (contact: Dr. Sarah Casewell)
  • Numerical simulations exploring the dynamics of protoplanetary discs, and how planets form and evolve within them (contact: Dr. Chris Nixon)
  • Planets around white dwarfs (contact: Dr Matt Burleigh)
  • Detection and Characterisation of exoplanets using photometry, particularly using NGTS. (contact: Dr Mike Goad, Dr Matt Burleigh).
  • Exoplanet atmospheres characterisation:  Inversion of spectroscopy from exoplanet transits and directly-imaged worlds to characterise their thermal structure, global composition and aerosol properties (contact:  Dr Leigh Fletcher)
  • Exoplanetary Magnetospheres and Aurorae (contact: Dr Jonathan Nichols)
  • Gravitational Instability theory of planet formation and super-migration of planets from ~ 100 au down to 0.1 au, including population synthesis models for the upcoming PLATO mission (contact: Prof. Sergei Nayakshin).

Wednesday 14 June 2017

Advanced Study Projects at Leicester

In their fourth year of undergraduate studies, Leicester's Physics and Astronomy students undertake a supervised reading project with an academic supervisor, helping them to develop critical evaluation skills for assessing scientific literature.  As planetary atmospheres is a relatively new discipline for Leicester, I've been offering a range of topics that take the students from Earth-based phenomena to my own work in solar system science.  Some of the projects on offer are listed below.

Climate Oscillations in Earth’s Atmosphere
Our planet’s atmosphere exhibits cycles of activity that operate over annual and multi-year timescales.  Prominent examples include the El Nino Southern Oscillation (ENSO), the Madden-Julian Oscillation (MJO), the North Atlantic Oscillation (NAO, which helps to modulate the weather patterns over the British Isles), and the Quasi-Biennial Oscillation (QBO) in the equatorial stratosphere.  These atmospheric cycles have only been identified by long-term tracking of meteorological phenomena, such as patterns or rainfall or sea-surface temperatures.  The underlying causes of some of these oscillations remain poorly understood, but there is evidence of connectivity, via teleconnections, between the different cycles.  This project will review the variety of long-term climate cycles, connections to anthropogenic climate change, and implications for cyclic activity on other worlds in our solar system.  You will gain an understanding of the forces influencing UK weather patterns, and the implications for global climate of disruptions to these delicate atmospheric balances.

Suggested Reading:
El Nino’s Extended Family:  From NASA’s Earth Observatory:
NOAA Website on El Nino and El Nina
North Atlantic Oscillation from UK Met Office:

Alien Skies:  Clouds from Ice Giants to Hot Jupiters
The bewildering variety of planetary environments discovered in the past two decades have provided an extreme test of our understanding of planetary atmospheric chemistry and cloud formation.  Models of planetary clouds are required to explain what the skies might look like on a hot roasting Jupiter, orbiting so close to its star that the temperatures soar to 3000K, and what they might be like on the coldest ice giant like Uranus or Neptune, at a frigid 50K.  This project will introduce you to the physics and chemistry of cloud formation, showing how condensation is influenced by the availability of volatile species and the temperature structure of an atmosphere.  It will take you from familiar clouds of water, to methane raindrops and hazes of iron and titanium.  We’ll conduct a thought experiment for how Jupiter’s cloud structure would change if it migrated inwards, closer and closer to the Sun, and use this to predict what the spectra of exoplanets might look like.

Suggested Reading:
Fletcher et al., 2014, Exploring the Diversity of Jupiter-Class Planets,
Sanchez-Lavega et al., 2004, Clouds in planetary atmospheres: A useful application of the Clausius-Clapeyron equation,
Marley et al., 2013, Clouds and Hazes in Exoplanet Atmospheres,

To the Surface of Europa
The next decade will see two ambitious missions providing new, close-in reconnaissance of Jupiter’s most enigmatic moon, Europa.  Europe’s Jupiter Icy Moons Explorer (JUICE) will conduct two close flybys of Europa, whereas NASA’s Europa Clipper will swing by more than 45 times.  These missions will pave the way for future landings on the surface, and will assess the capability of the Europan surface to host life.  This project will review our current understanding of the surface composition of Europa, its relation to the deep water-ice interior and the action of irradiation of surface materials.  You will look at the evidence for and against different surface acids, sulphates and salts, and their implications for the habitability of the surface.  You will develop an understanding of planetary ice spectroscopy, and the difficulties associated with distinguishing a unique composition from remote planetary measurements.  You will also assess the technological challenges associated with a mission to Jupiter’s moons, both in terms of available power, the harsh radiation environment, and the descent and landing concepts.

Suggested reading:
JUICE Red Book study report:
Greeley et al., 2004, The Geology of Europa (Chapter 15 of Jupiter. The planet, satellites and magnetosphere),
Phillips and Pappalardo, 2014, Europa Clipper Mission Concept, EOS 95, p165-167,

Anatomy of a Storm: From Earth to the Giant Planets
Planetary atmospheres serve as global-scale conveyor belts for heat, redistributing energy around the globe and influencing the pattern of weather and seasons.  On the giant planets, thundercloud systems produce lighting 10000x more intense than on Earth, and yet the same physics governs the formation of storm systems on all of the planets in our solar system, albeit under very different environmental conditions.  On Earth and on the giant planets, moist convection driven by the condensation of water (and the release of latent heat) controls this atmospheric heat engine, and shapes the appearance of a planet's atmosphere.  This project will compare and contrast evolving storm systems on terrestrial worlds and giant planets, identifying common processes and key differences between each world.  In particular, you will explore recent planetary-scale events (such as the disappearance and reappearance of Jupiter’s broad dark belts and the eruption of seasonal, globe-encircling storms on Saturn) and the importance of continuous versus triggered convective activity in planetary atmospheres.  You will develop an understanding of how satellite imaging and spectroscopy, either from Earth-orbiting satellites or planetary spaceprobes, contribute to our understanding of storm anatomy, and consider future measurement techniques to explore planetary atmospheric processes.

Suggested reading:
Introduction to Planetary Atmospheres, Agustin Sanchez-Lavega, CRC Press, 2011.
Dynamics of Jupiter’s Atmosphere,
Cloud Dynamics, Robert Houze, Academic Press, 1993.

Realm of the Giants: Influence of Migration
The formation of the four giant planets shaped the architecture of our entire planetary system, both by providing the bombardment that delivered water and organic materials to our forming planet, and by shielding us from further cataclysmic impacts.  Recent simulations of planetary dynamics suggest that giant planets, once formed in the cold outer solar system beyond the snow line, migrate inwards towards the host star.  You will explore the consequences for such an inward motion, both in terms of the chemical and climatic conditions on the giant planets themselves (e.g., the evaporation of cloud decks) as they evolve the ‘hot Jupiters’, and on the evolution of forming terrestrial worlds.  This will help you to understand the key differences in the atmospheric structure of the four giant planets and, potentially, the hypothesised Planet Nine.  You will also investigate why the inward migration of Jupiter was halted, and outward migration began (the Grand Tack hypothesis), and the implications of this for the evolution of our planetary system.

Suggested reading:
The Grand Tack Hypothesis,
Diversity of Jupiter-Class planets,
Planetary Sciences, de Pater and Lissauer,

Tuesday 6 June 2017

Uranus from Hubble

Whoever said that Uranus was the boring planet?  Here is Erich Karkoschka's time-lapse movie of Uranus over four years between 1994 and 1998 from the Hubble Space Telescope, as the south pole swings out of view and we head towards the 2007 equinox.  You can see considerable activity in the northern hemisphere as it becomes visible later in the sequence, and the dance of the satellites in the plane of the sky due to Uranus' weird axial tilt.  This movie was first published back in 1999

Friday 7 April 2017

Scientific Engagement in the Age of Social Media

The Royal Society asked me to contribute a blog post to their Inside Science blog, covering my use of social media to engage with the public.  You can find the Royal Society version here:

Dr. Leigh Fletcher is a University Research Fellow at the University of Leicester specialising in the exploration of the extreme weather and climate on planets throughout our Solar System.  In this blog post, he reflects on the use of social media and blogging to rapidly engage with a wide, international audience in his research.

Like it or loath it, social media has radically altered the ways in which we communicate with others, receive and interact with news stories, and form opinions about the world around us.  Today, eleven years after Twitter first exploded onto the scene, introducing tweets, hashtags and RTs into our vocabulary, we cannot even conceive of a news story not being disseminated instantaneously around our ever-shrinking planet.  Like many young scientists, I had always used traditional methods of engaging with the public – visiting schools to run demos; giving lectures to public societies; writing articles for newspapers and websites, and so on.  But suddenly blogging (and Twitter’s own micro-blogging in 140 characters) gave me a voice to immediately connect with that audience.  Let’s be clear – there’s no substitute to face-to-face engagement, but these digital communications allow me to reach a far wider and more diverse audience than I could otherwise.  And it has had other scientific benefits, as you’ll see below.

Engagement with “Impact”

I was given somewhat of an unfair head start with Twitter.  I’d signed up out of curiosity in May 2009, while I was a postdoc working at NASA’s Jet Propulsion Laboratory and I was travelling out to a conference in Kyoto.  Part of my job was to run regular observing programmes of Jupiter and Saturn from the telescopes in Hawaii.  Sounds wonderful, until you realise that I was doing most of this remotely from a darkened office in the middle of the night, with lots of coffee and the odd chocolate hobnob for company.  Then, in July 2009, we started to hear whispers that Jupiter had been dealt a bruising blow by a passing comet or asteroid.  I was on the observatory that night, and started to ‘live tweet’ what we were seeing, in a chain of 140-character tweets.  Faster than any news service, people were learning about this huge impact (which left a scar on Jupiter that was the size of the Pacific ocean) in real time – and the more retweets I got, the more exciting I found it.  It brought me to the attention of regular news services, who would then contact me for comments.  Where there were misunderstandings, I could correct them immediately.  Where there were questions, I could try to answer directly.  And when I didn’t know the answer, it was fine to be honest and admit it – it was all part of the fun!

That was eight years ago, and it’s true to say that not everyone is able to have the same ‘right place, right time’ experience with social media.  But I continued to tweet.  I’d share links to news stories related to my field (giant planet atmospheres), providing brief commentaries on what I thought about the work.  I’d share pictures and photographs of the planets, sometimes including raw data to show the process of acquiring, reducing and analysing astronomical data.  I’d describe what I was working on, to show the daily life of a research scientist.  I’d use Twitter to advertise public appearances, to engage with reporters, to update people on the missions and telescope observations that I was involved in.  I’d write lay summaries of my scientific articles for my blog, and post links to them on Twitter.  And whenever I had an important appearance coming up (like TV or radio), I’d write a blogpost to get all my ideas in order to anticipate the questions.  I’d never ever ever share what I’d had for breakfast.   And that meant that people ‘following’ my tweets would know what they were getting – a microchannel for news and insights about the exploration of the giant planets.  And a direct line to me, as a scientist.

Networking in the Twittersphere

But one of the most unexpected benefits of Twitter (at least back in 2009), was the world of communication it opened up with my fellow researchers.  Today, there’s a huge active community of planetary science tweeps (i.e., people who tweet).  This online community has been wonderful – sharing ideas, helping each other out, providing advice, and just providing an avenue to vent about things that aren’t going right.  This is real-life academia, and a much truer reflection of a life in research than anything I’ve seen elsewhere.  It’s opened my eyes to the struggles and challenges faced by minorities, and to my own biases in thinking.  As much as any academic conference that I’ve been able to attend, it’s shown me what others in my field are working on, what they’re struggling with, and how they’re approaching new problems.  And when these tweeps do find themselves on the same continent and timezone, there’ll almost certainly be a tweetup (i.e., social meeting) of like-minded people.  We’ve even started putting our twitter handles (i.e., @LeighFletcher) on our conference name badges, and in our conference slides, so that the conversation can continue long after the face-to-face meeting is over.

So, as a scientist, I have certainly benefitted enormously from this instantaneous communication – a connection with my peers that I wouldn’t have otherwise, and something that wasn’t happening only a decade ago.  When I can’t go to a conference, I’ll follow the twitter feed from my network.  When I’m waiting with baited breath for news to break, I’ll follow the twitter hashtag.  When I want to share something exciting I’m working on, I’ll craft it into 140 characters.

But what about the public?  What do they get from following scientists on twitter?  Well, just think back to whenever you’ve been ‘lucky’ enough to have your work featured in the news – were you frustrated that your words were simplified?  Shortened?  The emphasis was in exactly the wrong place, twisting your words?  Well, if you were frustrated, imagine how it feels to be a layperson trying to make sense of what you’ve done and why.  They’re having to see it through the filter of the media which, as we all know, are biased to whatever sells papers and prone to alternative facts.  Twitter gives scientists a genuine voice - an opportunity to engage, share and explain – and in my experience, the public enjoys having this direct, virtual access to experts.  It shows us to be human and fallible, but passionate and excited to have the opportunity to do this work.  I can think of no better way to be an ambassador for science and technology.

Thursday 30 March 2017

ERC-Funded Postdoc in our Team

Advertising the first ERC-funded postdoctoral position in Leicester's Planetary Atmospheres team - please do get in touch with any queries!

Postdoctoral Research Associate in Giant Planet Atmospheres
Physics and Astronomy Department, University of Leicester
Salary Grade 7 - £32,958 to £38,183 per annum
Full-time open-ended contract subject to external fixed-term funding.
Full Details:

Ref: SEN00830

The Physics and Astronomy Department at the University of Leicester wishes to appoint a postdoctoral researcher to undertake a programme of original research in the field of giant planet atmospheric science, utilising remote sensing data from a range of space- and ground-based observatories.  You will join a planetary science team addressing the aims of a grant awarded by the European Research Council (ERC) to Dr. Leigh Fletcher.  The appointment will initially be for a period of up to four years.

The “GIANTCLIMES” programme seeks to study the climates of the four giant planets over large spans of time, allowing us to investigate cycles of meteorology, circulation, and chemical processes shaping the environments on these worlds.  Inversions of planetary spectra, from the ultraviolet to the microwave, will be used to reconstruct these atmospheres in three dimensions to explore their temporal variability and the processes coupling different atmospheric regimes. You will analyse subsets of data from Juno, Cassini, Spitzer and the James Webb Space Telescope (among others), complemented by observations from Earth-based facilities.  We are therefore particularly interested in candidates with a background in planetary atmospheres and spectroscopic modelling techniques, but all applicants with a strong background in planetary science are encouraged to apply.

You will be expected to carry out independent and collaborative research for this project and to disseminate the results to the international scientific community.  There will be significant opportunities to collaborate within Leicester’s Planetary Science team (whose existing research includes planetary magnetospheres, ionospheres, atmospheres and surface science), Earth Observation group, and with an international team specialising in radiative transfer and spectral inversion for planetary atmospheres.

In addition to the online application form, applicants are requested to provide:  [1] a CV and publication list; [2] academic references covering your research career to date; [3] a cover letter detailing how your prior experience and future research aims are commensurate with the broad aims of the programme outlined above.  Full details on how to apply can be found here:

Informal enquiries are welcome and should be made to Dr. Leigh Fletcher on

The closing date for this post is midnight on 5 April 2017.

Wednesday 29 March 2017

Vice Chair of COSPAR Sub-Commission B5

I received an email this morning from Aaron Janofsky, Associate Director of the COSPAR Secretariat, confirming that I have been elected as the Vice Chair of COSPAR Sub-Commission B5 (Outer Planets and their Satellites).  Linda Spilker, Cassini's Project Scientist and Chair of this Sub-Commission, had first asked me about this at the Division of Planetary Sciences meeting last October, but I'm delighted to be helping out with COSPAR for the next three years (2016-2020).

The International Council of Scientific Unions (ICSU), now the International Council for Science, established its Committee on Space Research (COSPAR) during an international meeting in London in 1958. COSPAR's first Space Science Symposium was organised in Nice in January 1960.  From the COSPAR website:

"COSPAR's objectives are to promote on an international level scientific research in space, with emphasis on the exchange of results, information and opinions, and to provide a forum, open to all scientists, for the discussion of problems that may affect scientific space research. These objectives are achieved through the organisation of Scientific Assemblies, publications and other means."

There are eight scientific commissions.  I am now a member of Scientific Commission B: Space Studies of the Earth-Moon System, Planets, and Small Bodies of the Solar System.  This covers "the planetary bodies of the solar system (including the Earth), especially evolutionary, dynamic and structural aspects; planetary atmospheres are included insofar as these are essential attributes of their main body; smaller bodies, including satellites, planetary rings, asteroids, comets, meteorites, and cosmic dust."  It consists of five sub-commissions:

  • B1: Small Bodies
  • B2:  International Coordination of Space Techniques for Geodesy
  • B3: The Moon
  • B4: Terrestrial Planets
  • B5:  Outer Planets and Satellites

COSPAR Scientific Assemblies are held every two years (even numbered years). These events attract currently between 2000 and 3000 participants.  The 42nd Assembly will be held 14 - 22 July 2018 in Pasadena, California, and I've been helping to organise the giant planet sessions.  Previous assemblies during my academic career have included:

2016 - Istanbul, Turkey - sadly cancelled at short notice, so I didn't get to visit Istanbul.
2014 - Moscow, Russia
2012 - Mysore, India
2010 - Bremen, Germany - my second COSPAR meeting.
2008 - Montréal, Canada
2006 - Beijing, China - my first experience of COSPAR as an ESA-sponsored student.

Exciting times ahead!

Friday 17 March 2017

JUICE Moves into Phase C

Some excellent news to round the week off - the JUICE mission has passed its PDR (Preliminary Design Review), which means that the mission can officially move from Phase B2 (the preliminary definition phase, where we've been ever since mission adoption in November 2014) into Phase C (the detailed definition phase).  This is a pretty important milestone in the life cycle of a mission, which proceeds throughout this whole implementation phase (B2/C/D/E1).  Phase D is the qualification and production phase, and Phase E1 is the start of the utilisation phase.  The most exciting thing is that the main contractor, Airbus DS, can begin building the prototypes.

From the ESA website:

JUICE will be equipped with 10 state-of-the-art instruments, including cameras, an ice-penetrating radar, an altimeter, radio-science experiments, and sensors to monitor the magnetic fields and charged particles in the Jovian system.

In order to ensure it can address these goals in the challenging Jovian environment, the spacecraft's design has to meet stringent requirements.

An important milestone was reached earlier this month, when the preliminary design of JUICE and its interfaces with the scientific instruments and the ground stations were fixed, which will now allow a prototype spacecraft to be built for rigorous testing.

The review also confirmed that the 5.3 tonne spacecraft will be compatible with its Ariane 5 launcher. Operating in the outer Solar System, far from the Sun, means that JUICE needs a large solar array: two wings of five panels each are foreseen, which will cover a total surface area of nearly 100 m², capable of providing 820 W at Jupiter by the end of the mission.

After launch, JUICE will make five gravity-assist flybys in total: one each at Mars and Venus, and three at Earth, to set it on course for Jupiter. Its solar panels will have to cope with a range of temperatures such that when it is flying closer to the Sun during the Venus flyby, the solar wings will be tilted to avoid excessive temperatures damaging the solar cells.

The spacecraft's main engine will be used to enter orbit around the giant planet, and later around Jupiter's largest moon, Ganymede. As such, the engine design has also been critically reviewed at this stage.

Special measures will allow JUICE to cope with the extremely harsh radiation that it must endure for several years around Jupiter. This means careful selection of components and materials, as well as radiation shielding.

One particularly important topic is JUICE's electromagnetic 'cleanliness'. Because a key goal is to monitor the magnetic fields and charged particles at Jupiter, it is imperative that any electromagnetic fields generated by the spacecraft itself do not interfere with the sensitive scientific measurements. This will be achieved by the careful design of the solar array electrical architecture, the power distribution unit, and the reaction wheels – a type of flywheel that stabilises the attitude.

The review also ensured that JUICE will meet strict planetary protection guidelines, because it is imperative to minimise the risk that the potentially habitable ocean moons, particularly Europa, might be contaminated by viruses, bacteria or spores carried by the spacecraft from Earth. Therefore, mission plans ensure that JUICE will not crash into Europa, on a timescale of hundreds of years.

"The spacecraft design has been extensively and positively reviewed, and confirmed to address the many critical mission requirements," says Giuseppe Sarri, JUICE Project Manager. "So far we are on schedule, and are delighted to begin the development stage of this ambitious large-class mission."
ESA's industrial partners, led by Airbus, now have the go-ahead to start building the prototype spacecraft units that will subjected to tough tests to simulate the conditions expected during launch, as well as the extreme range of environmental conditions.

Once the design is proved beyond doubt, the flight model – the one that will actually go into space – will be built.

TEXES on Gemini North: Blazing Jupiter!

All of this week the TEXES team has been out on Mauna Kea running a programme of observations that included ten hours of time scanning Jupiter's tropics.  I proposed this to solve a key issue that we have - TEXES has provided fantastic spectral maps from the IRTF but with a limited spatial resolution from the 3-m primary mirror, whereas VISIR on the VLT (among others) provides superb imaging at high spatial resolution, but without decent spectroscopy.  By moving TEXES to Gemini-North for this special run, we were able to get the best of both worlds.

Sadly neither I nor the Leicester team could join them this time, but Tommy Greathouse, Glenn Orton, James Sinclair and Rohini Giles were sending me nearly continuous updates, and provided the data in a raw form on Tuesday morning.  I processed the spectral data into a map at just one wavelength (1165 cm-1, which senses deep temperatures and jovian aerosols, and always contains a lot of structure) to share in the Gemini e-cast.  There's also a nifty 3-colour image, generated from three wavelengths in the same spectral setting, which we'll be using in a future GeminiFocus magazine.  Needless to say, we're all pretty delighted with these data - the highest spatial-resolution spectral map of Jupiter ever acquired, period.  This is going to keep us going for years.

TEXES Gemini and Jupiter:

To truly understand the atmospheric phenomena at work in Jupiter, we must investigate three different domains - spatial, temporal, and spectral.  Past investigations have allowed us to target one of these domains, but today we are able to explore all three by combining the Gemini observatory, the TEXES spectrograph and the worldwide campaign of Earth-based support for NASA’s Juno mission.  This three-colour map reveals Jupiter’s weather layer near 8.6 microns, where Jupiter’s spectrum is governed by temperatures, cloud opacity, and gaseous species like deuterated methane and phosphine. The map was constructed from spectral scans over two nights (March 12th-13th 2017), and represents the highest spatial resolution ever achieved by the TEXES instrument.  Every pixel in this map represents a spectrum of Jupiter.  Red colours use a wavelength that senses deep, warm temperatures at the cloud tops; blue colours sense cooler temperatures at higher altitudes near the tropopause, and green colours sense an intermediate altitude.  The equatorial zone and the Great Red Spot in the bottom right are cold and dark at all three wavelengths.  The turbulent wake to the west of the Great Red Spot is darker (cooler) and distinct from the rest of Jupiter’s South Equatorial Belt.  An outbreak of dark, cold and cloudy plumes can be seen in the southern belt near 270W.  Finally, the pattern of cold, cloudy plumes (dark) and warm, bright hotspots (white) can be seen encircling the planet near latitude 7N, on the edge of Jupiter’s Northern Equatorial Belt.

Credit:  TEXES team & L.N. Fletcher/University of Leicester, UK.

From the Gemini e-cast #93 (March 16th 2017)

TEXES, the visiting high-resolution mid-IR spectrograph, is back for another visit on Gemini North. This time the instrument is supporting a wide-ranging set of science programs, including summer-solstice observations of Saturn’s polar vortex, three programs studying Jupiter’s atmosphere, stratosphere and aurora, and (beyond the solar system) studies of the chemistry of the gaps in protoplanetary disks, organics in hot star-forming cores and the motions of gas in embedded super star clusters. At mid-IR wavelengths most of the seeing is due to image motion, which is removed by the rapid tip-tilt secondary mirror on Gemini, producing diffraction-limited images as small as 0.3 arcseconds without the use of adaptive optics.

The TEXES team has been sharing part of each night with GMOS CCD commissioning activities, reported in the previous story in this newscast, and the team is grateful for their flexibility in accommodating this TEXES visitor instrument run.

The TEXES team and Gemini staff preparing the instrument to mount on the up-looking port of Gemini North in March 2017. The beachballs are part of the instrument’s helium overflow system.

Jupiter in the 8-micron region, in a spectral scan taken by TEXES on Gemini North, March 2017. Note the cool wake of the Great Red Spot (lower right). For more details and a full color mid-IR image of the Jupiter weather layer, see the upcoming April issue of GeminiFocus. Image credit: TEXES team & L.N. Fletcher/University of Leicester, UK.

Wednesday 15 March 2017

Ten Years of the European Research Council

I was honoured to be listed among Leicester's ERC grant holders in a recent press release coinciding with the tenth anniversary of the European Research Council.  A copy of the text can be found below, or via Leicester's website:

More details of this anniversary can be found here:

Researchers based at UK institutions won the largest share of mid-career and proof-of-concept grants handed out by the European Research Council in the latest awards rounds.

The news comes in the week that the European Research Council – a success story of the EU’s Horizon 2020 programme – marks its tenth anniversary with ‘ERC week’ (13-17 March) and celebrates its impact on strengthening Europe as a global centre of excellence in research.

The University of Leicester is a part of that success story having secured almost €10 million of ERC funding since 2011 – highly prestigious awards given only to ‘frontier’ research projects. ERC grant holders are in good company with some previous grant holders going on to win a Nobel Prize or to be awarded the Fields Medal.

UK-based researchers received a total of 58 grants in the latest Consolidator Grant round, equivalent to 18% of the awards handed out. This was followed by 48 for researchers located in Germany, 43 in France and 29 in the Netherlands.

Ten of the 44 Proof-of-Concept grants awarded by the ERC on 31 January went to researchers who will work at UK universities. Germany and Spain will host the second and third most grantees with six and five recipients respectively. This is the third time that the UK has topped the Proof-of-Concept awards recipient list since it voted to leave the EU in June 2016.

Leicester’s ERC grant holders include: Leigh Fletcher- Physics Consolidator Grant (2016) c. E €2 million.; Richard Alexander - Physics Consolidator Grant (2015) c. €2 million; Clare Anderson - History Starting Grant  (2013) – c. €1.5 million; Laura Morales - Politics Starting Grant  (2011) – c. €1.5 million; and David Mattingly - Archaeology Advanced Grant (2011) – c. €2.5 million. You can find out a bit more about their groundbreaking research on the Research and Enterprise funding pages.

Professor Iain Gillespie, Pro Vice Chancellor for Research and Enterprise commented: “We are very pleased to celebrate the achievements of our European Research Council (ERC) grant holders on the ten-year anniversary of the European Research Council scheme.

“These researchers epitomise leadership in world-class research, and we are proud that they also represent Leicester’s continuing, strong engagement with the European research community.”

Academic and research staff are reminded that the Treasury is continuing to financially underwrite UK participation in EU projects submitted before any official Brexit takes place. Funding will be guaranteed for UK organisations submitting projects before an official exit, even if the project will continue beyond the UK's membership of the European Union.