Much of our information about this eruption has come from the European Space Agency’s Envisat satellite, which is a state-of-the-art meteorological instrument in orbit around Earth.  In this article, we’ll take a look at this device, the awesome phenomenon of the eruption itself, and the larger scientific value of studying events like this.

In the study of our planet, we humans are hampered by our very smallness, and the brevity of our lives.  To us, 1821 seems like a long time ago.  If a volcano waits that long between eruptions, we might get a false sense of security- but the people of Iceland have been watching volcanoes for a long time, and they know better.  They know that to a volcano, 1821 was only yesterday.  It’s just long enough for the pressure to build up again- and Iceland has an awful lot of pressure.

The reason is a stroke of amazingly bad luck.  This poor island is the only piece of real estate on the planet that exists directly over not one, but two, of Earth’s pressure vents.

One of these pressure vents is the boundary between two tectonic plates.  America is on one plate and Eurasia is on another.  These plates literally float on the liquid rock of the planet’s mantle, and at the boundary between the two, that liquid rock sometimes seeps through.

Now, there is also another formation called a hotspot, which is made by a huge column of molten rock welling up under the surface.  As you might imagine, this makes the rock above the column bulge up.  If it happens on the ocean floor, it can make an island.

Now, just imagine these two things happening in the same place: a hotspot makes an island right over the boundary between two tectonic plates.  This incredibly unlikely coincidence would create an island which was constantly leaking magma and gases from deep within the Earth.

OK, you don’t have to imagine it; you can just look at the globe.  The winner of our Unluckiest Island in the World Award is Iceland, which is created by an enormous hotspot, and also exactly straddles the Mid-Oceanic Ridge which separates the American tectonic plate from the Eurasian one.  At some unknown time in the future, that column of magma under the hotspot is going to blow, and the resulting eruption will be one of the most destructive events in the life of the planet.

To their great credit, the Icelandic people have made good use of this energy.  Iceland currently leads the world in the generation of electricity by geothermal means.  Sitting on top of a hotspot does have its advantages.

And there’s another good side to all this, if you’re a planetary scientist: Iceland gives you a lot to study.  The island is like a geothermal laboratory where the workings of a planet can be studied in detail.  By looking at Iceland, we can see the interplay of forces that also exist on other small, rocky bodies.  Volcanoes, both active and extinct, have been observed on several other worlds in the solar system.  For instance, Mars has a huge mountain called Olympus Mons (appropriate, don’t you think?) which is a volcanic cone so high that its peak is outside the atmosphere.  Volcanoes have also been observed on some of the system’s moons, and recent evidence indicates that Venus may have active volcanoes, too.  This is one of those lucky instances where Earth presents us with an analog of something that exists on other worlds.  By studying the one we’ve got here, we can, in a way, study the ones out there, too.  The things that we learn about planetary forces and how they interact will also be true on those other worlds.

And that brings us to Envisat.  This satellite, which was designed for studying the weather, has proven invaluable in observing the Eyjafjallajoekull eruption.  This is a good example of a spacecraft that has been adapted to a job which is beyond its originally intended design.

Envisat, launched by the European Space Agency in 2002, is the largest Earth-observing spacecraft ever built.  It is equipped with 10 instruments which perform both optical and radar observations of Earth and give a wealth of data on how the planet works, including factors contributing to global warming.

While a list of all the devices on Envisat would be tedious and exhausting, we can take a look at the two most important ones, both of which are new pieces of technology:

The biggest single instrument on Envisat is called Advanced Synthetic Aperture Radar (ASAR).  It is a significant improvement over any previous meteorological radar unit, with enhanced ability in coverage, range of incidence angles, polarization and modes of operation.  The elevation of the radar beam can be steered, and the observations can be made in swaths of varying width, either 100 or 400 km wide.

MERIS, the Medium Resolution Imaging Spectrometer, is designed to measure the solar radiation reflected by the Earth.  It can observe the entire planet in three days.  Its primary mission is studying the color of the water in oceans and coastal areas.  From this it is possible to derive measurements of chlorophyll pigment concentration in algae, suspended sediment concentration and aerosol loads over marine seas.  In addition, it is used for atmospheric and land monitoring.

Envisat has given us a view of this event that we have never had for any other volcanic eruption.  The satellite, of course, was specifically calibrated for measuring the characteristics of clouds, and a new algorithm had to be devised to adapt it to the volcanic ash plume.  This has been working very well, providing detailed information on the movement, altitude and size of particles involved.  Since the blanket of ash that is spread by an eruption is one of its most destructive aspects, knowing how it moves and where it settles will be of great importance in preparing for future events of this type, and in understanding volcanoes everywhere.

And by studying this one, we are studying a scaled-down model of Olympus Mons on Mars, the volcanoes of Jupiter’s moon Io, and all the other volcanoes of the solar system.  How convenient!

One good thing: amazingly, there have been no casualties from this eruption.  Several hundred households in the vicinity of the volcano had to be evacuated, but all survived.

At this writing (April 24) the eruption is still happening.  The initial plume of ash has subsided enough for air traffic to resume, but it will take days or even weeks to get all those stranded passengers to their destinations.  A news report from two days ago (see sources) says that there are still ominous rumblings coming from the volcano.  Events of this type sometimes continue sporadically for some time, so we may not have heard the last from this one.

Whatever happens, Envisat will be there to watch it.  Thanks to the ESA and their outstanding satellite, future vulcanologists will have an in-depth profile of this eruption to study for years to come.

Sources:

“ESA Observing the Earth: New Satellite Image of Volcanic Ash Cloud, 15 April 2010″ at website of the European Space Agency:  esa.int/esaEO/SEMFYR9MT7G_index_0.html

“ESA Observing the Earth: New Satellite Image of Ash Spewing From Iceland’s Volcano, 19 April 2010″ at website of the European Space Agency:  esa.int/esaEO/SEMM16XN58G_index_0.html

“ESA Missions Observing the Earth: Envisat Overview” at website of the European Space Agency:  esa.int/esaEO/SEMWYN2VQUD_index_0_m.html

“Tremors on the Increase at the Eyjafjallajoekull Volcano” at newspublic:  news-public.com/index.php?option=com_content&view=article&id=1707:tremors-on-the-increase-at-the-eyjafjallajoekull-volcano&catid=34&Itemid=65

“Icelandair reschedules Flights out of Glasgow Despite Keflavik Airport Closure” in IceNews: News From the Nordics 24 April 2010:  icenews.is/index.php/2010/04/24/icelandair-reschedules-flights-out-of-glasgow-despite-keflavik-airport-closure/

The fortuitous combination of atmospheric gases that may life as we know it possible may have a decidedly extraterrestrial origin, stemming not from the actions of terrestrial volcanoes but from the appearance of comets.

Scientists have long been puzzled by the mixture of gases in the Earth’s atmosphere ”“ and by the origins of those gases. For years one of the most popular theories has been that the gases in the Earth’s atmosphere are the result of the eruption of volcanoes. As those gases bubbled up from those ancient volcanoes, the theory goes, they helped to create the atmosphere as we know it today.

But recently researchers at the University of Manchester in the UK came up with a different theory for the origins of the Earthly atmosphere, based on their findings after they collected samples of krypton gas hundreds of meters below New Mexico.

Researcher Greg Holland and his colleagues at the University of Manchester found that the area they studied was rich in heavier isotopes of krypton but poorer in lighter versions of the gas. In fact the composition of the samples closely resembled that found in meteorites, lending further credence to an exterritorial origin of the terrestrial atmosphere.

The comet theory supposes that the current atmosphere of the Earth has its origins not in volcanoes that spewed krypton and other gases into the air but in the bombardment of the earth by thousands icy comets. Specifically this emerging research is focused on the Kupier Belt, which formed when the solar system was born. The millions of icy bodies in the Kupier belt have been found to contain a noble gas signature very similar to that of the Earth’s present atmosphere.

Scientists already know that a shift in the orbit of gas giant Jupiter took place some 4.5 billion years ago, and that shift may have been enough to move the Kupier belt and release those comets on a collision course with Earth. It is an interesting theory, and one that is bound to gain additional attention as new evidence is discovered.

These three missions are really just variations on the same theme. The probes themselves are very similar to each other, using many of the same kinds of equipment and ground facilities and even some of the same personnel, which made the design and preparatory phases much quicker and easier than if each mission had started from scratch. The word “Express” in the names of the Mars and Venus probes refers to the fact that they were constructed and launched in record time, and with relatively low cost. Besides being stellar achievements in space science (pun intended!) they are also models of the kind of faster and more efficient missions that have become the norm in recent years. These missions prove the point that while space exploration will always be an expensive and lengthy undertaking, there are ways to greatly limit the cost and the amount of time needed for preparation.

Venus Express was launched from Baikonur, Kazakhstan on November 9, 2005 aboard a Soyuz-Fregat launcher. It traveled through space for 155 days, arriving at Venus in April 2006. Its mission was primarily to study the atmosphere and weather patterns on Venus, which are quite different from the kinds of patterns that we see here on Earth, despite the basic physical similarity of the two planets. The mission’s assignments included several firsts on Venus:

1. First global monitoring of the composition of the lower atmosphere in near-infrared transparency “windows.”

2. First coherent study of atmospheric temperature and dynamics at different levels of atmosphere, from the surface up to 200 km.

3. First measurements from orbit of global surface temperature distribution.

4. First study of middle and upper atmosphere dynamics from oxygen and nitrogen oxide emissions.

5. First measurements of non-thermal atmospheric escape.

6. First coherent observations of Venus in the spectral range from ultraviolet to thermal infrared.

7. First application of solar/stellar occultation technique at Venus to analyse how light is absorbed by the atmosphere, revealing atmospheric characteristics.

8. First use of 3D ion mass analyser, high-energy resolution electron spectrometer and energetic neutral atom imager.

9. First sounding of top-side ionospheric structure.

Venus Express was designed to address several open questions suggested by previous research. One of the most baffling mysteries is the cause of the super-fast atmospheric rotation and hurricane-force winds that have been observed on Venus. The Venusian atmosphere is whipping around the planet in a vast, global motion that is more than 60 times the speed of the planet’s rotation. This is a mystery, since such rapid motion cannot be explained by any conventional theory of atmospheric dynamics. Venus Express was designed to study the atmosphere in an effort to discover where all that energy is coming from. Another mystery is the double atmospheric vortex that has been observed at both Venusian poles, and has persisted for the entire observation period. The fact that similar features exist at both of the Venusian poles indicates a global symmetry that has so far eluded explanation. Scientists do not know how these features maintain their shape, and will be observing them closely in an attempt to figure out their dynamics.

Another part of Venus Express’ mission was the study of certain mysterious ultraviolet markings that have been seen at the tops of Venusian clouds. The upper clouds have areas visible in the ultraviolet that mysteriously absorb half of the solar energy received by the planet. The origin of these markings, and their remarkable absorption power, were among the questions being asked by Venus Express.

While the probe was designed to study the composition and dynamics of the Venusian atmosphere, it is also able to gain some information about the surface underneath that atmosphere. For instance, one of the questions regarding Venus is the nature and extent of volcanic activity on the planet, and how recently that activity occurred. Because it is capable of compiling detailed data on the temperature distribution and chemical composition of the atmosphere, Venus Express is capable of sensing both the heat of a volcanic eruption, and the chemicals that such an eruption would release into the air. By doing this, the probe should be able to spot places where eruptions have happened recently and determine how frequently they have occurred. In addition, Venus Express should be able to obtain valuable data on surface temperature, mineralogy, chemical weathering and the occurrence of earthquakes.

Since Venus Express has been in orbit around Venus for some time now, it has been able to obtain preliminary data on some of these questions. The picture that is emerging is of a planet that has changed radically from its earlier days. While Venus is hot and dry today, there is growing evidence that it may have been much more earthlike in its infancy.

For instance, Venus Express has observed that there is a color difference between the highland regions of Venus and the lowlands. On Earth, such a color difference would indicate that the highlands are composed primarily of granite. Granite is a relatively light rock formed by the action of water on basalt. In order for large amounts of granite to be present on the planet today, there must have been a lot of water sometime in the past.

In fact, theories of planetary formation would lead us to think that Venus and Earth started out with similar amounts of water. The two planets were formed from the same protoplanetary material, and were subjected to the same cometary bombardment in the early history of the solar system. Because of this, there is every reason to think that the two planets were once much more similar than they are today.

On Earth, granite literally floats on the heavier molten rock underneath, and forms the basis of the continents. So, when we look at Venus today and see highland regions that resemble the continental masses of Earth, the obvious conclusion is that these are the ancient continents of Venus, and that they were once surrounded by oceans as extensive as those on Earth. We are looking back billions of years, to a time when Venus, once called “Earth’s twin,” may have really deserved that title.

The question is unavoidable: was there life? Given the data that we have at the moment, we can’t answer that question- but it certainly is an intriguing possibility.

There is also some new data on the UV markings at the polar regions. It has been determined that these are caused by plumes of UV-absorbing material that has been brought up from deep in the atmosphere by convection currents. In other words, these UV-absorbing regions are really just the tops of tall columns of material. Where they well up, areas of high absorption are created, and the areas where they do not appear remain UV bright. That’s the phenomenon that is taking place, but the reason for it, and the exact nature of the absorbing material, are still unknown.

In regard to the vortexes at the north and south poles, we now know that they are much more variable than was originally thought. Observations on successive orbits have shown that the formations change their shape quickly and extensively, sometimes forming two separate “eyes” and sometimes a single oval or circular formation. A classic “eye of the hurricane” shape has been observed at the center of the south polar vortex. The dynamics of these features seem to be very complex, and will warrant much observation in the future.

Venus Express has also seen an eerie infrared glow in the night-time atmosphere of Venus, caused by nitric oxide which is produced when the sun’s radiation bombards the atmosphere and breaks up molecules, which recombine and release energy in the form of infrared light. This night glow can tell us much about the composition and movement of the atmosphere.

These are only a few of the things being learned from Venus Express. A full discussion of the data is far beyond the scope of this humble article. (For those who want more detail, the ESA website provides fascinating reading.) The probe continues to function well, and its mission has now been extended through December of 2012. Considering the huge success of the mission so far, we can only expect more great things in the future.

As new data comes in, it will be covered here. Watch this site for updates.

Sources:

Space Topics: Venus Express at website of the Planetary Society: planetary.org/explore/topics/venus_express/

Venus Express mission page at ESA website: esa.int/esaMI/Venus_Express/index.html

Venus Express Education and Outreach website maintained by the University of Wisconsin-Madison: venus.wisc.edu/

Malik, Tariq: A Cloudy Target: Europe’s Venus Probe to Explore Shrouded Planet at SPACE.com: space.com/businesstechnology/051026_techwed_venusexp.html

The Jupiter flyby was a huge success, allowing observations of the giant planet and its moons in unprecedented detail.  Among other things, information was gathered about the atmosphere and weather of Jupiter.  Data on cloud composition was collected by the visible light, infrared and ultraviolet remote sensing devices, and ammonia was observed welling up from the lower atmosphere to form clouds.  Lightning strikes were observed at the poles, the first polar lightning ever seen off Earth, and from this it was learned that heat moves evenly through water clouds at all latitudes across Jupiter.  New Horizons also made size and speed measurements of waves in the Jovian atmosphere, indicating strong storm activity beneath, and obtained close-up images of the Little Red Spot, a smaller version of the Great Red Spot.  The smaller feature is about half the size of the bigger one, or about 70 per cent of Earth’s diameter.

New Horizons obtained the clearest images yet of the tenuous Jovian rings.  Here clumps of material were observed that may be from a recent impact within the ring system.  The probe got a detailed view of the ring dynamics involved here, with moons Metis and Adrastea shepherding the materials around the rings.  A search for small moons within the rings yielded negative results.

The probe performed observations of Jupiter’s four largest moons, focusing especially on Io, closest to Jupiter and volcanically active.  Eleven volcanic plumes of varying size were seen, three for the first time.  One of these, a 200-mile-high eruption from the volcano Tvashtar, offered a chance to see the structure and motion of the plume as it condensed and fell back to the surface.  Instruments picked up infrared radiation from at least 36 volcanoes on Io with lava temperatures about 1900 degrees Fahrenheit, which is comparable to volcanoes on Earth.  Io is the most active body in the solar system, and more than 20 geological changes had occurred since the Galileo Jupiter orbiter was there in 2001.  Observations of Io while in Jupiter’s shadow showed glowing clouds over many of the volcanoes, a possible source of gas for Io’s atmosphere.

The probe passed down Jupiter’s magnetotail and got the closest-ever look at this region.  Particle detectors indicated that volcanic material from Io moves down the tail in slow-moving blobs.  Scientists are hoping to learn how these gases are ionized, trapped and energized by Jupiter’s magnetic field, and then finally ejected from the system.

New Horizons left Cape Canaveral in January, 2006.  It is the fastest spacecraft ever built, reaching Jupiter in only 13 months.  It is now about halfway between the orbits of Jupiter and Saturn, more than 743 million miles from Earth, and it will fly past Pluto and its moons Charon, Nix and Hydra in July 2015 before going deeper into the Kuiper Belt.

At present, the mission continues to go well.  In November of 2009, the probe was brought out of hibernation to repoint the communications dish antenna in order to keep up with the changing position of Earth around the sun.  This wake-up also provided an opportunity to download several months of stored data, correct a minor bug in the fault protection system software, perform adjustments to refine the craft’s trajectory, and upload instructions for the running of the craft from now until its next scheduled wake up in January 2010.

While New Horizons will not reach its destination until 2015, it will be able to perform some observations of Pluto and its largest moon, Charon, about a year earlier.  It will be taking pictures of the two at that point, and a few months later, it will be able to generate a map of Pluto.

The long approach will give an opportunity to watch seasonal changes in Pluto’s atmosphere.    Since 1989, Pluto has been heading away from the sun.  In 1999, it crossed the orbit of Neptune, once again becoming the outermost of the nine traditional planets.  It is now heading into its 200-year winter, when its atmosphere is expected to freeze and fall to the surface as snow, and because of this, the New Horizons mission will be the last chance to study the atmosphere of Pluto.  The probe will obtain information about its chemical composition, and also allow observations of cloud formation.  Clouds, probably composed of nitrogen or carbon monoxide, have already been observed in the thin atmosphere of Pluto.

Once New Horizons has passed Pluto, it will head out into the Kuiper Belt to find and study some of the mysterious bodies that exist there, which are thought to be icy and comet-like.  The probe will conduct a search for Kuiper Belt bodies, and when it finds them, will modify its own course to approach and observe them.  It is hoped that New Horizons will find six to ten of these bodies to study.

The outermost region of the solar system is a vast, dark area that is only beginning to reveal its secrets.   What else is out there?  Over the next few years, we will begin to find out.