Royal Astro Society Winton Capital Prize

An excellent piece of news to round off my first year back in the UK after leaving the Jet Propulsion Laboratory:  I’ve been awarded the Royal Astronomical Society Winton Capital Prize (2011) awarded “for research by a Post Doctoral Fellow in a UK institution in geophysics whose career has shown the most promising development”  More details can be found below.

Here’s the news release from the Royal Astronomical Society (2011)

Astronomy and Geophysics Award Announcement (2009)

The Winton Capital Awards

Two prizes, sponsored by Winton Capital, for research by a Post Doctoral Fellow in a UK institution in respectively astronomy ('A') & geophysics ('G') whose career has shown the most promising development. At the time of nomination candidates, in normal circumstances, should have completed their PhD no more than 5 years previously.

Saturn's Cosmic Dimmer Switch

In a paper published today by a CIRS-team colleague of mine, Liming Li, we demonstrate how Saturn’s thermal emission seems to vary with time.  Most of this is likely due to Saturn’s seasonal variability (see the earlier entry on Saturn’s Changing Seasons), but there is some evidence that Cassini’s observations of Saturn show a different thermal emission when compared to Voyager’s observations, exactly one Saturnian year ago.  The next step in the analysis is to study Saturn’s absorbed power, as the balance between the power absorbed and emitted is vital to understand the thermal evolution of the planet.  Watch this space!

Liming Li, Barney Conrath , Peter Gierasch , Richard Achterberg , Conor Nixon , Amy Simon-Miller , F. Flasar , Don Banfield , Kevin Baines , Robert West , Andrew Ingersoll , Carolyn C. Porco , Ashwin Vasavada , Anthony Del Genio , Andrei Mamoutkine , Marcia Segura , Gordon Bjoraker , Glenn Orton , Leigh Fletcher , Patrick Irwin , Peter Read , Thierry Fouchet, Saturn’s Emitted Power, J. Geophys. Res., 115, E11002 (http://dx.doi.org/10.1029/2010JE003631)

http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20101110/

Like a cosmic lightbulb on a dimmer switch, Saturn emitted gradually less energy each year from 2005 to 2009, according to observations by NASA's Cassini spacecraft. But unlike an ordinary bulb, Saturn's southern hemisphere consistently emitted more energy than its northern one. On top of that, energy levels changed with the seasons and differed from the last time a spacecraft visited Saturn in the early 1980s. These never-before-seen trends came from a detailed analysis of long-term data from the composite infrared spectrometer (CIRS), an instrument built by NASA's Goddard Space Flight Center in Greenbelt, Md., as well as a comparison with earlier data from NASA's Voyager spacecraft. When combined with information about the energy coming to Saturn from the sun, the results could help scientists understand the nature of Saturn's internal heat source.

"The fact that Saturn actually emits more than twice the energy it absorbs from the sun has been a puzzle for many decades now," said Kevin Baines, a Cassini team scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif., and a co-author on a new paper about Saturn's energy output. "What generates that extra energy? This paper represents the first step in that analysis."

The research, reported this week in the Journal of Geophysical Research-Planets, was led by Liming Li of Cornell University in Ithaca, N.Y. (now at the University of Houston).

"The Cassini CIRS data are very valuable because they give us a nearly complete picture of Saturn," Li said. "This is the only single data set that provides so much information about this planet, and it's the first time that anybody has been able to study the power emitted by one of the giant planets in such detail."

The planets in our solar system lose energy in the form of heat radiation in wavelengths that are invisible to the human eye. The CIRS instrument picks up wavelengths in the thermal infrared region, far enough beyond red light where the wavelengths correspond to heat emission.

"In planetary science, we tend to think of planets as losing power evenly in all directions and at a steady rate," Li said. "Now we know Saturn is not doing that." (Power is the amount of energy emitted per unit of time.)

Instead, Saturn's flow of outgoing energy was lopsided, with its southern hemisphere giving off about one-sixth more energy than the northern one, Li explains. This effect matched Saturn's seasons: during those five Earth-years, it was summer in the southern hemisphere and winter in the northern one. (A season on Saturn lasts about seven Earth-years.) Like Earth, Saturn has these seasons because the planet is tilted on its axis, so one hemisphere receives more energy from the sun and experiences summer, while the other receives less energy and is shrouded in winter. Saturn's equinox, when the sun was directly over the equator, occurred in August 2009.

In the study, Saturn's seasons looked Earth-like in another way: in each hemisphere, its effective temperature, which characterizes its thermal emission to space, started to warm up or cool down as a change of season approached. The effective temperature provides a simple way to track the response of Saturn's atmosphere to the seasonal changes, which is complicated because Saturn's weather is variable and the atmosphere tends to retain heat. Cassini's observations revealed that the effective temperature in the northern hemisphere gradually dropped from 2005 to 2008 and started to warm up again by 2009. In the southern hemisphere, the effective temperature cooled from 2005 to 2009.

The emitted energy for each hemisphere rose and fell along with the effective temperature. Even so, during this five-year period, the planet as a whole seemed to be slowly cooling down and emitting less energy.

To find out if similar changes were happening one Saturn-year ago, the researchers looked at data collected by the Voyager spacecraft in 1980 and 1981 and did not see the imbalance between the southern and northern hemispheres. Instead, the two regions were much more consistent with each other.

Why wouldn't Voyager have seen the same summer-versus-winter difference between the two hemispheres? One explanation is that cloud patterns at depth could have fluctuated, blocking and scattering infrared light differently.

"It's reasonable to think that the changes in Saturn's emitted power are related to cloud cover," says Amy Simon-Miller, who heads the Planetary Systems Laboratory at Goddard and is a co-author on the paper. "As the amount of cloud cover changes, the amount of radiation escaping into space also changes. This might vary during a single season and from one Saturn-year to another. But to fully understand what is happening on Saturn, we will need the other half of the picture: the amount of power being absorbed by the planet."

Scientists will be doing that as a next step by comparing the instrument's findings to data obtained by Cassini's imaging cameras and infrared mapping spectrometer instrument. The spectrometer, in particular, measures the amount of sunlight reflected by Saturn. Because scientists know the total amount of solar energy delivered to Saturn, they can derive the amount of sunlight absorbed by the planet and discern how much heat the planet itself is emitting. These calculations help scientists tackle what the actual source of that warming might be and whether it changes.

Better understanding Saturn's internal heat flow "will significantly deepen our understanding of the weather, internal structure and evolution of Saturn and the other giant planets," Li said.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency, and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA Goddard, where the instrument was built.

More Cassini information is available at http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini .

Written by Elizabeth Zubritsky and Jia-Rui Cook

Jia-Rui Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
jia-rui.c.cook@jpl.nasa.gov

Elizabeth Zubritsky 301-614-3458
Goddard Space Flight Center, Greenbelt, Md.
elizabeth.a.zubritsky@nasa.gov

2010-380

Revival of Jupiter's South Equatorial Belt

On November 9th 2010, Jupiter’s ‘missing’ South Equatorial Belt (SEB) showed signs of a spectacular, violent and eruptive revival, initiating a chain of events that will ultimately revive the typical brown colour of the belt.  A huge plume of bright material erupted in the SEB, prompting us to scramble for time on Gemini, Keck, IRTF and VLT to study this unprecedented opportunity to observe a rare and mysterious phenomenon caused by the planet's winds and cloud chemistry.

The following text has been created by amalgamating the original press releases from JPL, University of Berkeley and the Gemini Observatory.  Text credits go to Robert Sanders (Berkeley) and Priscilla Vega/Jia-Rui Cook (JPL).  Nice write-ups were also on space.com. 

Stripes Are Back in Season on Jupiter

Earlier this year, amateur astronomers noticed that the long-standing stripe, known as the South Equatorial Belt (SEB), just south of Jupiter's equator, had turned white (see the Hubble space telescope image comparison on the right, noting the missing belt). In early November, amateur astronomer Christopher Go of Cebu City in the Philippines observed a prominent bright spot in the unusually whitened belt, piquing the interest of professional and amateur astronomers around the world.  After follow-up observations with NASA's Infrared Telescope Facility (IRTF), the 10-meter Keck telescope and the 8-meter Gemini telescope, all atop Mauna Kea in Hawaii, scientists now believe the stripe is making a comeback.

NASA's Infrared Telescope Facility False obtained this false-color composite image on Nov. 16 (right). The prominent region just to the left of the center, expanded in the insert, shows the region of the South Equatorial Belt outbreak. In the coming weeks, further outbreaks are expected to take place to the west (left) of those seen in this image. The clear atmospheric regions (in red) will begin to fill this latitude band at the same time as the dark brown color typical of this region returns.

Astronomers announced first-glimpse images of the reappearing stripe Nov. 9.  "The reason Jupiter seemed to 'lose' this band — camouflaging itself among the surrounding white bands — is that the usual downwelling winds that are dry and keep the region clear of clouds died down," said Glenn Orton, a research scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "One of the things we were looking for in the infrared was evidence that the darker material appearing in visible light was actually the start of clearing in the cloud deck, and that is precisely what we saw."

This white cloud deck is made up of white ammonia ice. When the white clouds float at a higher altitude, they obscure the view of the lower brown clouds. Every few decades or so, the South Equatorial Belt turns completely white for perhaps one to three years, an event that has puzzled scientists for decades. This extreme change in appearance has only been seen with the South Equatorial Belt, making it unique to Jupiter and to the entire solar system.

The bright storm that Go observed in the faded belt was quite unusual, said Imke de Pater, UC Berkeley professor of astronomy.  "At infrared wavelengths, images in reflected sunlight show that the spot is a tremendously energetic 'outburst,' a vigorous storm that reaches extreme high altitudes," de Pater said. "The storms are surrounded by darker areas, bluish-grey in the visible, indicative of 'clearings' in the cloud deck."

To confirm the presence of such clearings, the team obtained data at longer wavelengths (5 micron) sensitive to thermal emission from Jupiter’s deep atmosphere. These data confirm that the visibly dark material indeed is being seen through holes in the cloud deck, "perhaps signaling the start of the SEB revival," added Glenn Orton. 

The white band wasn't the only change on the big, gaseous planet. At the same time, Jupiter's Great Red Spot became a darker red color. Orton said the color of the spot — a giant storm on Jupiter that is three times the size of Earth and a century or more old — will likely brighten a bit again as the South Equatorial Belt makes its comeback.

The South Equatorial Belt underwent a slight brightening, known as a "fade," just as NASA's New Horizons spacecraft was flying by on its way to Pluto in 2007. Then there was a rapid “revival” of its usual dark color three to four months later. The last full fade and revival was a double-header event, starting with a fade in 1989, revival in 1990, then another fade and revival in 1993. Similar events have been captured visually and photographically back to the early 20th century, and they are likely to be a long-term phenomenon in Jupiter’s atmosphere.

This false-color image, taken Nov. 11 by the Keck telescope (left), shows sunlight reflected off Jupiter's upper cloud deck — the same clouds that are seen in visible light. The bright spot in the South Equatorial Belt is the outbreak where winds are lofting particles to high altitudes. Click here for larger downloadable image and detailed caption and credits. (Credit: UC Berkeley, University of Toronto, University of San Carlos, Philippines)

Scientists are particularly interested in this event because it’s the first time they've been able to use modern instruments to determine the details of the chemical and dynamical changes of this phenomenon.  "These observations may help to unravel the mystery of why this transition occurs, and may allow us to understand the longevity of Jupiter's belt/zone structure," added Leigh Fletcher, a scientist at Oxford University in England.

The event also signifies another close collaboration between professional and amateur astronomers. The amateurs, located worldwide, are often well equipped with instrumentation and are able to track the rapid developments of planets in the solar system. These amateurs are collaborating with professionals to further study the changes that are of great value to scientists and researchers everywhere.

"I was fortunate to catch the outburst," Go said. "I had a meeting that evening, and it went late. I caught the outburst just in time as it was rising. Had I imaged earlier, I would not have caught it."

Go witnessed the disappearance of the stripe earlier this year, and in 2007 he was the first to catch the stripe's return. "I was able to catch it early this time around because I knew exactly what to look for," he said.

Since the discovery of the first spot, there have been several more outbreaks of varying strengths. The SEB revival is happening fast, with violent eruptions, de Pater said.  Observing this event carefully may help to refine the scientific questions that will be posed by NASA’s Juno spacecraft, due to arrive at Jupiter in 2016, and a larger mission to orbit Jupiter and explore its satellite Europa after 2020.  More observations at near- and mid-infrared wavelengths are planned for the coming weeks.

Image Captions:

Keck Images:  False color images of Jupiter and the SEB outbreak taken with the 10-meter W.M. Keck telescope in Hawaii on UT November 11, 2010, just 2 days after the initial discovery of the "outbreak". This false color composite is constructed from images taken in narrow-band filters centered at 1.21 micron (green), 1.58 micron (red), and 1.65 micron (blue). At 1.21 and 1.58 micron we see sunlight reflected off Jupiter's upper cloud deck - the same clouds that are seen in visible light. The narrow band image at 1.65 micron shows sunlight reflected back from hazes just above these clouds. The bright "spot" in the SEB is the outbreak where winds are lofting particles to high altitudes. Image Credit: James Graham (University of California, Berkeley and UofToronto/Dunlap Institute), Shelley Wright, Imke de Pater, Michael Wong (University of California, Berkeley). Christopher Go (University of San Carlos, Philippines) sharpened the images slightly using the RegiStax software, developed by Cor Berrevoets.

IRTF Images:  False color images of Jupiter and the SEB outbreak taken with the 3-meter NASA Infrared Telescope Facility in Hawaii on UT November 16, 2010. This image is a false color composite at three wavelengths that probe diagnostic altitudes in Jupiter's atmosphere: 1.58 microns (blue) sensitive to sunlight reflected from Jupiter's main cloud deck - also detected in visible light; 4.00 micron (green) detects sunlight reflected from higher-altitude particles well above the main deck; and 4.85 (red) micron detects the thermal emission arising from the tops of Jupiter's clouds, with the hottest emissions coming from the deepest atmosphere, and signifying regions with minimal overlying cloud cover. The prominent region just to the left of the center, and expanded in the insert, shows the region of the South Equatorial Belt (SEB) outbreak. The initial outbreak is identified at the upper right, with a second outbreak to the lower left. Between them, in red, is a region of clear atmosphere, probably the result of downwelling from the easternmost plume. In the coming weeks, further outbreaks are expected to take place to the west (left) of those seen in this image. The clear atmospheric regions (in red) will begin to fill this latitude band at the same time as the dark brown color typical of this region returns. Image credit: Glenn Orton, Padma Yanamandra-Fisher, Gregorio Villar (Jet Propulsion Laboratory, California Institute of Technology), David Griep (Institute for Astronomy, University of Hawaii), Leigh Fletcher (University of Oxford), Imke de Pater and Michael Wong (University of California, Berkeley).

Jupiter on the Sky at Night

In late August I was invited to Patrick Moore’s house to discuss ‘Events on Jupiter’ with another Jupiter aficionado, John Rogers.  We had an incredible day filming in Patrick’s study, and the show aired throughout September 2010. 

The program could be viewed for a short time here:

http://www.bbc.co.uk/programmes/b00tnwks

Ultimately the show could be found on the Sky at Night archive:

http://www.bbc.co.uk/science/space/skyatnight/

Next Big Names in Astronomy

A few weeks ago, the editor of Astronomy Now contacted me to talk about what life was like for a new researcher, just starting out on a career in astronomy.  Right now, at a time when research councils are reducing funding for science across the board, I think it’s a great idea to showcase some of the work that’s being done in the UK.  And it was very nice to be asked to be a part of this focus article!  The September issue of Astronomy Now is online now, and here’s the official blurb:

The Next Big Names in Astronomy

The future of astronomical research and space exploration lies with the young men and women at universities around the globe who are just starting out on a career in science. In this Focus, we meet five young post-docs who are already making names for themselves in their given fields. There's Dr Veronica Bray, who spends her days imaging the Moon with NASA's Lunar Reconnaissance Orbiter, or exploring craters on Jupiter's moons. Dr Leigh Fletcher at the University of Oxford has his hands in the pie of the biggest interplanetary spacecraft ever planned, the joint NASA/ESA Jupiter-Europa-Ganymede mission. Dr David Jess of Queen's University Belfast also has his attention on an object within our Solar System, at the very centre of it in fact: our Sun, and its mysteriously hot corona. Reaching out beyond our planetary neighbourhood, Dr Jim Geach of the University of Durham is seeking to answer the riddle of galaxy formation, while similarly Dr Ben Davies of the University of Leeds and the Rochester Institute of Technology is looking to solve the problem of how the most massive stars form.

No Debris from the 2010 Jupiter Impact

New and detailed observations from the NASA/ESA Hubble Space Telescope have provided insights into two recent events on Jupiter: the mysterious flash of light seen on 3 June and the recent disappearance of the planet’s dark Southern Equatorial Belt.

At 22:31 (CEST) on 3 June 2010 Australian amateur astronomer Anthony Wesley saw a two-second-long flash of light on the disc of Jupiter. He was watching a live video feed from his telescope. In the Philippines, amateur astronomer Chris Go confirmed that he had simultaneously recorded the transitory event on video. Wesley was the discoverer of the now world-famous July 2009 impact.

Astronomers around the world suspected that something significant must have hit the giant planet to unleash a flash of energy bright enough to be seen here on Earth, about 770 million kilometres away. But they didn’t know how just how big it was or how deeply it had penetrated into the atmosphere. Over the past two weeks there have been ongoing searches for the “black-eye” pattern of a deep direct hit like those left by former impactors.

The sharp vision and ultraviolet sensitivity of the Wide Field Camera 3 aboard the NASA/ESA Hubble Space Telescope were used to seek out any trace evidence of the aftermath of the cosmic collision. Images taken on 7 June — just over three days after the flash was sighted — show no sign of debris above Jupiter’s cloud tops. This means that the object didn’t descend beneath the clouds and explode as a fireball. If it had done, then dark sooty blast debris would have been ejected and would have rained down onto the clouds.

Instead the flash is thought to have come from a giant meteor burning up high above Jupiter’s cloud tops, which did not plunge deep enough into the atmosphere to explode and leave behind any telltale cloud of debris, as seen in previous Jupiter collisions.

“The cloud tops and the impact site would have appeared dark in the ultraviolet and visible images due to debris from an explosion,” says team member Heidi Hammel of the Space Science Institute in Boulder, Colorado, USA. "We can see no feature that has those distinguishing characteristics in the known vicinity of the impact, suggesting there was no major explosion and no ‘fireball’.”

Dark smudges marred Jupiter’s atmosphere when a series of fragments of Comet Shoemaker-Levy 9 hit Jupiter in July 1994. A similar phenomenon occurred in July 2009 when a suspected asteroid slammed into Jupiter. The latest intruder is estimated to be only a fraction of the size of these previous impactors and is thought to have been a meteor.

“Observations of these impacts provide a window on the past — onto the processes that shaped our Solar System in its early history,” says team member Leigh Fletcher of the University of Oxford, UK. “Comparing the two collisions — from 2009 and 2010 — will hopefully yield insights into the types of impact processes in the outer Solar System, and the physical and chemical response of Jupiter's atmosphere to these amazing events.”

As a bonus, Hubble’s observations also allowed scientists to get a close-up look at changes in Jupiter’s atmosphere following the disappearance of the dark cloud feature known as the Southern Equatorial Belt several months ago.

In the Hubble view, a slightly higher altitude layer of white ammonia ice crystal clouds appears to obscure the deeper, darker belt clouds. “Weather forecast for Jupiter’s Southern Equatorial Belt: cloudy with a chance of ammonia,” Hammel says.

The team predicts that these ammonia clouds should clear out in a few months, as they have done in the past. The clearing of the ammonia cloud layer should begin with a number of dark spots like those seen by Hubble along the boundary of the south tropical zone.

“The Hubble images tell us these spots are holes resulting from localised downdrafts. We often see these types of holes when a change is about to occur,” Simon-Miller says.

“The Southern Equatorial Belt last faded in the early 1970s. We haven’t been able to study this phenomenon at this level of detail before,” Simon-Miller adds. “The changes of the last few years are adding to an extraordinary database on dramatic cloud changes on Jupiter.”

Notes

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

The Jupiter Impact Science Team consists of Amy Simon-Miller (NASA Goddard Space Flight Center, USA); John T. Clarke (Boston University, USA); Leigh Fletcher (University of Oxford, UK); Heidi B. Hammel (Space Science Institute, USA); Keith S. Noll (Space Telescope Science Institute, USA); Glenn S. Orton (Jet Propulsion Laboratory, USA); Agustin Sanchez-Lavega (Universidad del Pais Vasco, Spain); Michael H. Wong and Imke de Pater (University of California — Berkeley, USA).

Image credit: NASA, ESA, M. H. Wong (University of California, Berkeley, USA), H. B. Hammel (Space Science Institute, Boulder, Colorado, USA), A. A. Simon-Miller (Goddard Space Flight Center, Greenbelt, Maryland, USA) and the Jupiter Impact Science Team.

Links

•NASA’s release: http://hubblesite.org/newscenter/archive/releases/2010/20/ 

•For images and more information about the 3 June 2010 Jupiter impact, visit: http://hubblesite.org/news/2010/16

•http://science.nasa.gov/science-news/science-at-nasa/2010/11jun_missingdebris/

Neptune's Carbon Monoxide

New results from the Herschel Observatory have reconfirmed previous findings of Neptune’s dual sources of carbon monoxide.  Eric Hand of Nature News provided an overview of these results, which also discusses our own results on Neptune’s CO abundance from the AKARI mid-infrared observations (referenced below).

http://www.nature.com/news/2010/100528/full/news.2010.269.html

Fletcher, L. N. , Drossart, P. , Burgdorf, M. , Orton, G. S. & Encrenaz, T. Astron. Astrophys. 514, A17 (2010).

Saturn's Changing Seasons

Cassini Science League Entry

NASA Planetary Photojournal

Saturn experiences seasons for the same reason that the Earth does - it's axis is tilted relative to it's orbit, so the angle of the Sun above the horizon varies over the course of the year.  With one crucial difference:  Saturn's orbit takes 30 Earth-years, so the seasons are incredibly long.  Cassini has now been observing Saturn for long enough to see the first signs of atmospheric changes related to the changing season.  To the best of my knowledge, this is the first time that we've been able to watch the seasons change on a gas giant from a visiting spacecraft.

The new Cassini thermal infrared results, which track the changing temperatures over the course of the mission, were recently published in the journal Icarus:

Fletcher, L.N., Achterberg, R.K., Greathouse, T.K., Orton, G.S., Conrath, B.J., Simon-Miller, A.A., Teanby, N., Guerlet, S., Irwin, P.G.J., Flasar, F.M., Seasonal Change on Saturn from Cassini/CIRS

Observations, 2004-2009, Icarus (2010), doi: http://dx.doi.org/10.1016/j.icarus.2010.01.022

BACKGROUND:

When Cassini first arrived in 2004, Saturn was in the middle of the balmy southern summer, with it's south pole oriented towards the Sun and the north pole shrouded in winter darkness.  Five years later, Cassini observed the ring-plane crossing, when Saturn's rings appear edge on from our viewpoint and both hemispheres are subject to the same amount of heating from the sun, so that we're now in southern autumn and northern spring.  The Cassini instruments, including the Composite Infrared Spectrometer (CIRS), have noted dramatic changes to the atmospheric temperature, composition and aerosol content as time has progressed.  As the spring hemisphere emerged from the shadow of the rings, CIRS measured 6-8 K substantial warming in the northern stratosphere, combined with a gradual cooling of the southern stratosphere.  Saturn's south polar hotspot is still there, but has cooled in the five years since it was first observed.  And Saturn's equator is showing evidence for complicated changes to the temperatures and winds, as Saturn's semi-annual oscillations (Orton et al., 2008, Nature) modulate the atmosphere.  Finally, the CIRS data show the effects of  growing hazes and aerosols in the springtime conditions, consistent with visible images showing the replacement of Saturn's northern blue hues of 2004 by the more familiar yellow-ochre colours as spring progresses.

Using a knowledge of how Saturn's atmospheric gases absorb solar energy (heating the atmosphere up) and emit thermal heat energy (cooling the atmosphere down), we were able to reproduce the observed seasonal changes with a climate model.  That climate model was then used to make predictions for Saturn's changes through to 2017, the end of Cassini's solstice mission.  The spring hemisphere will continue to warm, possibly with the formation of a north polar hotspot like the one we saw in the south.  The south will cool as it approaches winter, and moves into the shadow of Saturn's rings.  By 2017 the asymmetry in temperature we saw at the beginning of the mission will be almost completely reversed, and Cassini will have observed Saturn for almost half of it's year.  Such models provide us with an intricate understanding of how the climates on the outer planets respond to changes in the amount of solar energy, and provides another excellent example of how Cassini is helping to shape out understanding of atmospheric processes throughout our solar system.

CASSINI SCIENCE LEAGUE ENTRY

Saturn’s Seasons Are Made in the Shade

Saturn’s rings act like a broad-brimmed sunhat, shading large swaths of the planet’s face. Now, after six years of constant observation by the Cassini spacecraft, scientists have been able to observe the dramatic effects this cooling shadow creates in Saturn’s atmosphere.

This figure shows shifting stratospheric temperatures obtained by Cassini between 2005 to 2008. The difference between the temperatures is shown in the middle, with red indicating warming in the stratosphere and blue indicating cooling.

Saturn's atmosphere is affected by seasonal changes just like Earth's is, but perhaps even more so, because the poles spend nearly 15 Earth-years in winter darkness and the next 15 years in sunlight. On top of that, the cooling shadow of the rings causes differences in heating and sunlight-driven chemistry between the shaded and sunlit parts of Saturn's atmosphere.

Cassini's years in orbit around Saturn have produced the first long-term space-based measurements of seasonal change on a gas-giant planet. In particular, Cassini's composite infrared spectrometer has recorded seasonal changes in Saturn's atmosphere, witnessing rapid responses in the atmospheric temperatures and hazes as the equinox approached last August. At that time, the incoming sunlight hit the rings edge-on, reducing the ring shadow to just a thin line across the planet's middle. Mission scientists have been struck by how quickly the atmosphere changed in response to the shifting ring shadow.

Even though the ring-shaded portion of the atmosphere is cooler than the rest, the planet seems to quickly adjust the disequilibrium by filling the cool patches with warmer air. "Because the shadowed region of the atmosphere moves over time, it makes for interesting atmospheric dynamics in the regions newly emerging from ring shadow in the springtime," said researcher Leigh Fletcher of NASA's Jet Propulsion Laboratory and the University of Oxford. "Cassini found that Saturn's atmosphere changes drastically depending on what season you're in. When the shadow is gone, the atmosphere responds quickly by warming up."

As equinox approached last August, Saturn's northern spring hemisphere began to change rapidly, Fletcher said. The stratosphere in Saturn's northern mid-latitudes warmed faster than anywhere else on the planet as it emerged from the shadow of the rings. Between Cassini's arrival in 2004 and the spring equinox in 2009, that area warmed by 6 to 8 Kelvin (about 11 to 14 degrees Fahrenheit). At the same time, the blue shades seen in Saturn's northern hemisphere at the start of the mission were rapidly replaced by the more familiar yellow-ochre hues, demonstrating a close relation between season, temperatures and cloud colors. Saturn's warm south polar stratosphere was also seen to cool over the course of the mission, and Cassini scientists expect the development of an analogous warm north polar stratosphere as spring progresses.

Observing how the stew of gases in Saturn's atmosphere circulate, heat, and cool contributes to our basic understanding of planetary atmospheres, including Earth's, Fletcher said. "This sort of study places Earth's own seasonal variations into the context of seasonal changes throughout our solar system."

"In some ways, Saturn is a simpler system than Earth -- no biogenic influences on the climate, no surfaces or continents to interrupt the flow of the atmosphere from one place to the next," he said. "But in other ways, Saturn's atmosphere is complicated, with dynamics, wave activity and chemistry that scientists are still studying and trying to understand." Fletcher points to the example of a recently discovered long-lived equatorial wave pattern at Saturn that ripples back and forth within Saturn's upper atmosphere. In this region, temperatures switch from one altitude to the next in a candy cane-like, striped, hot-cold pattern. These varying temperatures force the wind in the region to keep changing direction from east to west, jumping back and forth. As a result, the entire region oscillates like a wave. (See http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20080507/.)

Cassini's mission was recently extended through 2017. This will be a particularly exciting time if the northern hemisphere continues to respond to the changing season as fast as it has in the past couple of years, said Fletcher. "We could start to see the development of a warm north polar stratosphere, mirroring the one observed in the south. We'll almost certainly see a 'flip' in Saturn's temperature field, and by the end of Cassini's lifetime, the northern hemisphere will be warmer than the south, almost the complete reverse of conditions at the start of the mission."

By the end of its mission, Cassini will have a record of Saturn's seasons for at least portions of spring, summer, autumn and winter, making Saturn the best-studied gas giant planet. "Cassini is the first planetary spacecraft in history to provide that opportunity," said Fletcher. "To really understand a planet's weather and environment, you have to watch how things change and evolve with time."

This Cassini Science League entry is an overview of a science paper authored, or co-authored, by at least one Cassini scientist. The information above was derived from or informed by the following publications:

1) “Seasonal Change on Saturn from Cassini/CIRS Observations, 2004-2009,” Leigh N. Fletcher (JPL and University of Oxford, U.K.); Richard K. Achterberg (University of Maryland, College Park); Thomas K. Greathouse (Southwest Research Institute, San Antonio, Texas); Glenn S. Orton (JPL); Barney J. Conrath (Cornell University, Ithaca, New York); Amy A. Simon-Miller (NASA Goddard Spaceflight Center, Greenbelt, Maryland); Nicholas Teanby (University of Oxford, Clarendon Laboratory, U.K.); Sandrine Guerlet (LESIA - Observatoire de Paris, Meudon, France); Patrick G.J. Irwin (University of Oxford, U.K.); F.M. Flasar (NASA Goddard Spaceflight Center), Icarus, in press, available online February 10, 2010. http://dx.doi.org/10.1016/j.icarus.2010.01.022


2) “Phosphine on Jupiter and Saturn from Cassini/CIRS,” L. N. Fletcher, G.S. Orton (JPL); P.G.J. Irwin, N.A. Teanby (University of Oxford, Clarendon Laboratory, U.K.), Icarus, Volume 202, Issue 2, Pages 543-564.


3) “Temperature and Composition of Saturn’s Polar Hot Spots and Hexagon,” L. N. Fletcher, P.G. J. Irwin (University of Oxford, Clarendon Laboratory, U.K.); G.S. Orton (JPL); N.A. Teanby (University of Oxford, Clarendon Laboratory) , R. K. Achterberg, G.L. Bjoraker (NASA Goddard Space Flight Center, Greenbelt, Maryland); Read, P. L. (University of Oxford, Clarendon Laboratory); A. A. Simon-Miller, (NASA Goddard Space Flight Center); C. Howett (University of Oxford, Clarendon Laboratory); R. de Kok, N. Bowles, S.B. Calcutt (University of Oxford, Clarendon Laboratory); B. Hesman, F.M. Flasar (NASA Goddard Space Flight Center) Science, January 4, 2008, Vol. 319, no. 5859, Pages 79-81.


4) 2008. Nature 453, 7192, p196-199. 10.1038/nature06897
“Semi-annual oscillations in Saturn’s low-latitude stratospheric temperatures,” G. S. Orton, P. A. Yanamandra-Fisher, B. M. Fisher, A. J. Friedson (JPL); Paul D. Parrish (University of Edinburgh, U.K.); Jesse F. Nelson (University of Maine, Orono); Amber Swenson Bauermeister University of California, Berkeley); Leigh Fletcher (JPL); Daniel Y. Gezari NASA Goddard Space Flight Center, Greenbelt, Maryland; Frank Varosi (University of Florida, Gainesville); Alan T. Tokunaga (University of Hawaii, Institute for Astronomy); John Caldwell(York Univesrity, Toronto, Canada); Kevin H. Baines (JPL); Joseph L. Hora (Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts); Michael E. Ressler (JPL); Takuya Fujiyoshi, Tetsuharu Fuse (Subaru Telescope, Hilo, Hawaii); Hagop Hagopian (University of California, Los Angeles); Terry Z. Martin (JPL); Jay T. Bergstralh (NASA Langley Research Center, Hampton, Virginia); Carly Howett (University of Oxford, Clarendon Laboratory), William F. Hoffmann (University of Arizona, Steward Observatory, Tuscon); Lynne K. Deutsch (W. M. Keck Observatory, Kamuela, Hawaii); Jeffrey E. an Cleve (Ball Aerospace and Technologies Corp., Boulder, Colorado); Eldar Noe (JPL);, Joseph D. Adams (Cornell University, Ithaca, New York); (W. M. Keck Observatory); Marc Kassis (NASA Infrared Telescope Facility, Hilo, Hawaii) Eric Tollestrup (deceased), Nature Volume 453, Issue 7192, Pages 196-199, May 8, 2008.

5) “An equatorial oscillation in Saturn's middle atmosphere,” T. Fouchet, S. Guerlet, (LESIA, Observatoire de Paris, Université Pierre et Marie Curie , Meudon, France); D. F. Strobel, Johns Hopkins University, Baltimore, Maryland) A. A. Simon-Miller NASA Goddard Space Flight Center, Greenbelt, Maryland); B. Bézard (LESIA, Observatoire de Paris); F.M. Flasar (NASA Goddard Space Flight Center) Nature, Volume 453, Pages 200-202, May 8, 2008.

Jupiter's Spot Seen Glowing

We’ve recently completed a long-term study of Jupiter’s Great Red Spot using a suite of ground-based observatories and spacecraft data to study the composition and dynamics of the solar system’s largest long-lived storm system.  The results are published in Icarus (http://dx.doi.org/10.1016/j.icarus.2010.01.005) and have been covered by several media sources:

BBC World Service: Science in Action

MSNBC Cosmic Log: How Jupiter Changes its Spots

ESO: Jupiter’s Spot Seen Glowing

JPL: See Spot on Jupiter. See Spot Glow

Wired Science:  Red in Jupiter’s Spot not what Astronomers Thought

Oxford:  Jupiter’s Red Spot has a Warm Heart

Space.com: Secrets of Jupiter's Great Red Spot Revealed in New Weather Map

From the text of the ESO/JPL/Oxford joint press release:

New ground-breaking thermal images obtained with ESO’s Very Large Telescope and other powerful ground-based telescopes show swirls of warmer air and cooler regions never seen before within Jupiter’s Great Red Spot, enabling scientists to make the first detailed interior weather map of the giant storm system and finding for the first time the intimate link between temperature, winds, pressure, composition and the colour of the Great Red Spot.

“This is our first detailed look inside the biggest storm of the solar system,” says Glenn Orton, who led the team of astronomers that made the study. “We once thought the Great Red Spot was a plain old oval without much structure, but these new results show that it is, in fact, extremely complicated.”

The observations reveal that the reddest colour of the Great Red Spot corresponds to a warm core within the otherwise cold storm system, and images show dark lanes at the edge of the storm where gases are descending into the deeper regions of the planet. The observations, detailed in a paper appearing in the journal Icarus, give scientists a sense of the circulation patterns within the solar system’s best-known storm system.

Sky gazers have been observing the Great Red Spot in one form or another for hundreds of years, with continuous observations of its current shape dating back to the 19th century. The spot, which is a cold region averaging about minus 160 degrees Celsius, is so wide that about three Earths could fit inside its boundaries.

The thermal images were mostly obtained with the VISIR [1] instrument attached to ESO’s Very Large Telescope in Chile, with additional data coming from the Gemini South telescope in Chile and the National Astronomical Observatory of Japan’s Subaru Telescope in Hawaii. The images have provided an unprecedented level of resolution and extended the coverage provided by NASA’s Galileo spacecraft in the late 1990s. Together with observations of the deep cloud structure by the 3-metre NASA Infrared Telescope Facility in Hawaii, the level of thermal detail observed from these giant observatories is comparable to visible-light images from the NASA/ESA Hubble Space Telescope for the first time.

“One of the most intriguing findings shows the most intense orange-red central part of the spot is about 3 to 4 degrees warmer than the environment around it,” says lead author Leigh Fletcher. This temperature difference might not seem like a lot, but it is enough to allow the storm circulation, usually counter-clockwise, to shift to a weak clockwise circulation in the very middle of the storm. Not only that, but on other parts of Jupiter, the temperature change is enough to alter wind velocities and affect cloud patterns in the belts and zones. 

“This is the first time we can say that there’s an intimate link between environmental conditions — temperature, winds, pressure and composition — and the actual colour of the Great Red Spot,” says Fletcher. “Although we can speculate, we still don’t know for sure which chemicals or processes are causing that deep red colour, but we do know now that it is related to changes in the environmental conditions right in the heart of the storm.” 

Notes:

[1] VISIR stands for VLT Imager and Spectrometer for mid Infrared (eso0417). It is a complex multi-mode instrument designed to operate in the 10 and 20 micron atmospheric windows, i.e. at wavelengths up to about 40 times longer than visible light, and to provide images as well as spectra.

More Information:

This research was presented in a paper to appear in Icarus:

Fletcher, L.N., Orton, G.S., Mousis, O., Yanamandra-Fisher, P., Parrish, P.D., Irwin, P.G.J., Fisher, B.M., Vanzi, L., Fujiyoshi, T., Fuse, T., Simon-Miller, A.A., Edkins, E., Hayward, T.L., De Buizer,

J., Thermal Structure and Composition of Jupiters Great Red Spot from High-Resolution Thermal Imaging, Icarus (2010), doi: http://dx.doi.org/10.1016/j.icarus.2010.01.005

The team is composed of Leigh N. Fletcher and P. G. J. Irwin (University of Oxford, UK), G. S. Orton, P. Yanamandra-Fisher, and B. M. Fisher (Jet Propulsion Laboratory, California Institute of Technology, USA), O. Mousis (Observatoire de Besançon, France, and University of Arizona, Tucson, USA), P. D. Parrish (University of Edinburgh, UK), L. Vanzi (Pontificia Universidad Catolica de Chile, Santiago, Chile), T. Fujiyoshi and T. Fuse (Subaru Telescope, National Astronomical Observatory of Japan, Hawaii, USA), A.A. Simon-Miller (NASA/Goddard Spaceflight Center, Greenbelt, Maryland, USA), E. Edkins (University of California, Santa Barbara, USA), T.L. Hayward (Gemini Observatory, La Serena, Chile), and J. De Buizer (SOFIA - USRA, NASA Ames Research Center, Moffet Field, CA 94035, USA). 

Leigh Fletcher was working at JPL during the study.

Notes about ESO:

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and VISTA, the world’s largest survey telescope. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Contacts

Henri Boffin
ESO Garching, Germany
Tel: +49 89 3200 6222
Cell: +49 174 515 43 24
Email: hboffin@eso.org

Jia-Rui C. Cook

Jet Propulsion Laboratory, Pasadena, USA

Tel: +1 818 354 0850

E-mail: jia-rui.c.cook@jpl.nasa.gov

Images

Jupiter’s Storms: Temperatures and Cloud Colors

Link to NASA Photo Journal
New thermal images from ESO’s Very Large Telescope (VLT) and other ground-based telescopes show swirls of warmer air and cooler regions never seen before within Jupiter’s Great Red Spot. The images enable scientists to make the first detailed weather map of the inside of the giant storm system. One observation illustrated by this image is the correspondence between a warm core within an otherwise cold storm system and the reddest colour of the Great Red Spot.

The image on the left was obtained with the VISIR on the VLT in Chile on May 18, 2008. It was taken in the infrared wavelength range of 10.8 microns, which is sensitive to Jupiter's atmospheric temperatures in the 300 to 600 millibar pressure range. That pressure range is close to the altitude of the white, red and brown aerosols seen in the visible-light image on the right, which was obtained by the Hubble Space Telescope on May 15, 2008. These images show the interaction of three of Jupiter's largest storms — the Great Red Spot and two smaller storms nicknamed Oval BA and Little Red Spot.

Credit: ESO/NASA/JPL/ESA/L. Fletcher

ADDITIONAL DETAILS:

Jupiter's Great Red Spot (GRS) is one of the best-known and most often observed meteorological features in our solar system.  However, until recently we knew very little about the interior temperatures and structure of the giant storm system, nor how it changed with time.  Much of what we learned came from visiting spacecraft (Galileo and Cassini), but they only provided isolated snapshots of the GRS, and couldn't resolve any small-scale details of the storms.  This paper reports thermal imaging of the storm and its surroundings from 8-m class observatories (ESO VLT, Subaru and Gemini), allowing us to see the thermal details of the eye of the storm for the first time.  Furthermore, as these 8-m observatories provide resolutions comparable to Hubble visible images, we're able to connect the temperatures and composition measured from the ground with the visible colouration of the storm.  We found that the deepest red colour of the GRS is associated with a core of warmer temperatures within a typically cold storm system, connecting the red colour to the physiochemical conditions of the clouds.  The warm core and associated red colours moved in position with time.  Furthermore, this small warm core affects the speed and direction of the winds in the very centre of the storm.

The extensive dataset contains a wealth of information about the detailed structure of the storm.  We found that aerosols and ammonia gas were depleted in a ring surrounding the storm, suggesting strong sinking of air at the storm's edge.  The shape and structure of the storm changes as you move deeper in the atmosphere, and the strongest upwelling (measured using gases as tracers of motion) is not right in the middle of the storm as we previously thought, but is closer to the northern edge of the GRS.  The clouds and hazes surrounding the GRS vary with time, as Jupiter experiences periodic outbursts and upheavals of the clouds that are still poorly understood, and as other large storm systems move close and exert forces on the atmosphere surrounding the GRS.  And finally, the GRS often has a thermal tail extending away to its southwest, that doesn't appear to have any counterpart in the clouds themselves.

These first detailed observations of the internal temperature and composition of the storm will present a new challenge to modellers seeking to understand how the GRS formed in the first place, and how it changes with time.  And a better model of Jupiter's largest storm will help us to understand the dynamics, chemistry and evolution of storms on other planets in our solar system and beyond.

QUESTIONS AND ANSWERS:

If we want to compare the intensity of the storm with something else, how big is it?

Think of fitting nearly three Earths end-to-end across the length of the interior of the Great Red Spot - that gives you an idea of how large this huge storm really is.

Is it right to call the atmosphere over the spot “air”?

Yes, if you think of it as a gas - just like the Earth's atmosphere is gas.  Jupiter, in fact, is mostly gas, and what we're seeing is simply the tops of clouds in the visible.  The temperatures and other physical properties we're picking up are those of the (mostly) molecular hydrogen and helium gas, with traces of ammonia, methane and phosphine.  But you want to be sure this isn't Earth-like air, whose composition is much different: something like 70% molecular nitrogen, most of the rest molecular oxygen, with trace amounts of carbon dioxide and water vapor.

So what's the next step for exploration of Jupiter and its moons?

NASA is due to launch the Juno mission to Jupiter in August 2011. Meanwhile, NASA and the European Space Agency are developing concepts for a joint mission to the Jovian moons Europa and Ganymede, both of which are thought to harbor oceans' worth of liquid water beneath their icy surfaces. Launch of the Europa Jupiter System Mission could come around 2020.

How would the presence of a warm, weakly rotating core likely affect the dynamics of the GRS in terms of its persistence and structure?

The atmospheric temperatures and the circulation of the storm are intimately linked together - this warm core means that the anticlockwise winds of the GRS can actually reverse, just slightly, right in the heart of the spot.   In terms of structure, we know that this warm core is a persistent feature at all the altitudes we have access to, but we don't know how deep the storm penetrates into Jupiter's deep troposphere.  That will have to wait for the next generation of spacecraft observations.  Finally, the paper shows that the warm core was there every time we looked, over a three year period.  So it seems to be a long-lived feature of the storm, and the next generation of dynamical models will be needed to explain why this warm heart is present, and whether it's typical of storm systems on gas giant planets.

How is it this structure hasn't been detected before?

We've never had the capabilities of large 8-m observatories before!  As the technology has improved, the spatial resolution achievable from here on the ground has grown in leaps and bounds.  The new results surpass even Galileo and Cassini in terms of their quality.  WIthout these world-class observatories, we wouldn't have had access to the internal environmental conditions of the storm.

The mystery of the GRS origin will have to wait for new dynamical models to be produced which fully capture the features we're seeing in our data.  We study the GRS because it's the best example of a giant storm on a gas planet, and creates a template for our understanding of storms in our solar system and beyond.  But it's not the only example, and clues of the GRS origin might be better gleaned from it's companion, Oval BA, which reddened in 2005/06 and is now the second largest storm system on Jupiter.  So Oval BA might tell us about the birth of giant red storms, whereas the GRS tells us about why their stable for such long periods of time.

UK Spending Cuts and Cassini

Copied here is a Memorandum submitted by Early Career Cassini Scientists (FC 10) to the Science and Technology Committee Inquiry into `The Impact of Spending on Science and Scientific Research' in 2010.  For background to the story, see Jonathan Amos' BBC news article "Cassini flies on but with UK involvement in doubt"

To the Science and Technology Committee,

 We, the undersigned, are all early-career scientists at a range of UK institutions, primarily involved in planetary science using the Cassini spacecraft. We have prepared the attached document for submission to the Science and Technology Committee inquiry, detailing the impact the recently announced cuts will have upon our research, careers and opportunities in the UK.

Declaration of Interests:
Those of us currently studying for PhDs are supported by the STFC. Those of us employed as research associates are funded by the STFC.


Yours Sincerely,

Early Career Cassini Scientists

Imperial College London, Space & Atmospheric Physics Group
Dr. Jun Cui Research Associate
Jack Cutler PhD Student
Dr. Caitriona Jackman Research Associate
Dr. Laurent Lamy Research Associate
Daniel Went PhD Student
Dr Laurence Billingham Research Associate (Earth Science & Engineering Group)

University of Leicester, Department of Physics & Astronomy
David Andrews PhD Student
Kay Clarke PhD Student
Stephanie Kellett PhD Student
Dr. Henrik Melin Research Associate
Dr. Jonathan Nichols Research Associate
Dr. Gabrielle Provan Research Associate
Dr. Dean Talboys Research Associate

Queen Mary University of London
Nathan Allcock PhD Student
Dr. Gareth A. Williams Cassini ISS Operations Programmer

Mullard Space Science Laboratory, University College London
Dr. Christopher S. Arridge STFC Postdoctoral Research Fellow
Glynn Collinson PhD Student
Sheila Kanani PhD Student
Dr. Adam Masters Research Associate
Anne Wellbrock PhD Student

University of Oxford, Atmospheric, Oceanic and Planetary Physics Group
Dr. Leigh Fletcher Research Associate
Dr. Jane Hurley Research Associate
Dane Tice DPhil Student

[1] We, the undersigned, are early-career scientists at a range of UK institutions, primarily involved in planetary science using the Cassini spacecraft - a highly successful international interplanetary mission that has been studying Saturn, its moons and local environment, since its arrival in 2004.

[2] Worryingly, the recently published STFC Science Programme Prioritisation indicates that a "managed withdrawal" will take place from funding of operational costs for the UK-funded instruments on board the Cassini spacecraft. Furthermore, the report recommends that "support be withdrawn for exploitation grants of those projects not recommended for funding", ultimately leading to the cessation of Cassini-based science in the UK. We feel that the STFC Programme Prioritisation does not accurately reflect the community's views as expressed in the recent Near-Universe Advisory Panel (NUAP) report, to which we contributed extensively. STFC should provide a full explanation of how the community's input contributed to the Programme Prioritisation. It appears to have been ignored.

[3] The planned programme of managed withdrawal is by no means unique to those of us involved with the Cassini mission. The current prioritisation process seeks to cut all UK-instrument support for space missions actively making in-situ plasma measurements.  While we recognise the external economic pressures faced by the research councils, we believe that the long-term implications of such wide-ranging cuts will be severe, and will have a very real impact both to our research, and to the long-term future of planetary science.

[4] As early-career scientists we are deeply concerned about the future of space physics within the UK, and in particular the loss of jobs, skills and training opportunities.  The result of STFC's prioritisation process will force UK based early-career scientists abroad, or into leaving the field completely. Meanwhile, current PhD students face the very real possibility that there will be no UK planetary space physics community for them to join once they have completed their studies, should they wish to continue their research.  If we fail to retain our world-leading capabilities within planetary space physics, there will not be a future generation of scientists able to exploit upcoming missions, such as the Bepi-Colombo mission to Mercury and the potential Europa-Jupiter System Mission.

[5] The international Cassini scientific investigation is in its prime - a quick search reveals over 2000 scientific papers published by nearly 4000 authors to date at a rate that has increased by 30% year-on-year since the spacecraft's arrival at Saturn[1]. NASA are currently reviewing a proposed extension of the Cassini mission to 2017, and are due to announce their decision on February 8, 2010. Scientists in the UK contributed to one of the discoveries of the decade, by detecting the magnetic signature of plumes of water ice ejected from Saturn's icy moon, Enceladus. It is now recognised that there is a very real possibility that a liquid ocean exists beneath the moon's icy shell, posing the profound question - is there life on Enceladus? This question, and the tools required to answer it, has an excellent ability to inspire lasting interest in the STEM subjects in the public, across all age ranges.

[6] The UK is a world leader in space physics.  Clearly, this reputation cannot be maintained if the UK's involvement is categorically withdrawn from one of the most successful international scientific missions to another planet thus far.  Scientists around the world are relying on the UK's expertise in operating key instruments on board the spacecraft.  It seems tragic to turn off healthy world-leading instruments on a £2bn spacecraft, denying both UK and our international collaborators a vital resource in our field. Serious questions must be asked about the value of these decisions that have been made by the STFC Council. The STFC has a Royal Charter to "promote and support high-quality scientific and engineering research" - our view is that this is not currently being achieved.

Early Career Cassini Scientists


[1] Thomson Reuters Web of Science, topic "Cassini", Number of papers published per year, 2004 - 2009 inclusive

Return to the Dreaming Spires

After two years enjoying the Southern California sunshine at the Jet Propulsion Laboratory, I was offered the Glasstone Science Research fellowship to return to the UK and continue with my planetary research.  This was a tremendous opportunity - Oxford’s Atmospheric, Oceanic and Planetary Physics department is an international player in the world of planetary science, with involvement in both NASA and ESA missions to all of the planets in the solar system, notably Jupiter and Saturn via the Galileo and Cassini missions.  It was an offer I couldn’t refuse!

Two Glasstone Fellowships are awarded each year, one for a man and one for a women, to conduct scientific research in a wide range of disciplines, from Plant Sciences, Chemistry (Inorganic, Organic or Physical), Engineering, Mathematics (including Computer Science and Statistics), Materials, and, thankfully, Physics.  Samuel Glasstone (b. 1897, d. 1986) was a popular science author on a wide range of topics, most notably on the environmental effects of nuclear weapons and nuclear energy, and was hailed as one of the best technical writers of the 20th century.  Later he wrote, for NASA, books on space exploration (“Source book on Space Sciences”, 1965; “The Book of Mars”, 1968.  Glasstone’s wife,  Violette, had studied botany in Oxford, and upon his death he chose to leave the university a considerable sum of money to support young researchers from all over the world. 

As the lucky recipient of one of the Glasstone Fellowships, I’m enormously in their debt.  I intend to use the funds to continue my involvement in planetary exploration whilst broadening my horizons to other disciplines, seeking a cross-disciplinary interpretation of the new discoveries we make.  Finally, I believe that planetary science serves as a ‘beacon subject’, attracting bright young minds into scientific and engineering disciplines, so I hope I can play a role in making our results accessible to all.  With the global problems of climate change and adaptation that we face, encouraging a new generation of problem-solvers is the least we can do to help!