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/

As often happens in the field of space exploration, the idea was way ahead of the reality.  The mission’s unusual name is a salute to Italian astrophysicist Guiseppe “Bepi” Colombo, who originally figured out the course that such a flight should take.  In 1975, Colombo proposed a plan to NASA by which a spacecraft could swing close to Mercury three times by making gravity-assist maneuvers around Venus.  The plan would have worked, but was too ambitious for NASA at the time; it got shelved and forgotten.  Now the years have passed, and things that were once unattainable seem within reach.

Unfortunately, Bepi Colombo died in 1984.  Another sad fact about space exploration is that those who think up the great ideas often don’t live long enough to see them come of age.  The mission that he proposed years ago is going to happen at last, and it will bear his name.

BepiColombo will be launched aboard a Soyuz-Fregat rocket from Kourou, French Guiana.   The date seems to be uncertain; the JAXA website says it’s 2013, but the ESA site says 2014.  (It’s possible that the mission plans were changed in the early stages, as often happens, and that these two postings reflect different versions of the plan.)  BepiColombo’s objectives are to make precise observations of the planet’s magnetic field, magnetosphere, interior and surface.

One of the main questions that it will try to answer is why, of all the planets in the solar system, only Earth and Mercury have active magnetic fields.   Actually, we know why Earth has one, but knowing that just makes Mercury more perplexing.   Earth has an active magnetic field because it has a molten layer surrounding its solid inner core.  The innermost core is compressed into a solid by gravity, but above that, there is a viscous, molten layer called the outer mantle.  The fluid contains iron, and as it moves around the core, the entire planet becomes a giant electrical generator.  The principal is exactly the same as generators here on Earth, in which a rotor moves around a stator, creating an electrical field.  In this case, we see the basic concept expanded to a planetary scale, and the field that results is so strong, it forms lines of magnetic force that stretch around the whole planet.  The important point here is that without the molten outer layer and the solid inner layer moving past each other, you wouldn’t get the magnetic field.  It’s being constantly generated and replenished by that spinning motion inside the planet.

If Earth’s molten outer core were to cool down and become solid- which will happen eventually, in our planet’s old age- the magnetic field would no longer be generated.  Of course, this does not mean that the earth’s magnetic field would suddenly disappear.  We all know that when you place a piece of iron in a magnetic field for a while, it becomes magnetized, too.  If you cut off the magnetism, the iron will still retain some of that energy, but it will be weaker than the original source, and it will fade with time.  If the iron is all mixed up with a bunch of rocks and other stuff, and the mixture is of a very uneven consistency, then the magnetism will fade at an uneven rate.  If there’s more iron in one spot than another, then of course, that spot will hold the magnetism longer.  Eventually you will end up with a glob of iron and rock and stuff which has a very weak, uneven magnetic field around it.  If you had the instruments to measure it, it would be immediately obvious that this was an old, fading field rather than an active one that is being constantly replenished from within.

Let’s leave Mercury for a moment and look at Mars.  This planet has a weak, spotty magnetic field, which tells us that it once had a molten outer core like Earth’s, but that core has now become solid and is no longer generating magnetism.  This is not surprising, because Mars is smaller than Earth, and must have lost the initial heat of its birth faster than Earth has.  Mars is said to have a “fossil” magnetic field.

So here we have the two extremes: Earth with its active field, and poor old Mars with its weak, faded one.  In the old days, when we were looking at Mercury from afar, the popular thought was that it would probably have no magnetic field at all, or if it did, the field would only be a fossil field.   The reasoning was that since Mercury is considerably smaller than either Earth or Mars, it should have long since lost all of the original heat from its formation.  And despite the fact that Mercury is the closest planet to the sun, it still isn’t hot enough to melt rock.  After all, the planet’s surface is still quite solid.  Since the inner region of the planet should have lost all of its original heat, and is insulated by all the rock that lies above it, it must be cooler than the sun-baked surface.  So, if the surface is solid, the core should be, too.  Looking at it logically, you get a picture of a small planet with a relatively cool and very solid interior.

Or so we thought, back in the olden days.  When Mariner 10 made its flyby of Mercury in March of 1974, it revealed what nobody had expected to find: an active magnetic field.  Amazingly, this little planet seems to have a molten portion in its interior, just as Earth does.  Either that, or the current theory about how planetary magnetic fields are generated is completely wrong.  If that’s the case, it means we’ll have to throw away all the textbooks and start over at square one- and since this would be a scandalous waste of paper, we can only hope that it won’t be necessary.  A less revolutionary explanation is that Mercury may have large amounts of radioactive material in its interior, which generates enough heat to melt iron and form a molten mantle- but at the moment, this is pure speculation.

In any case, the planetary scientists certainly want to have a closer look.  The part of BepiColombo’s instrumentation which was contributed by JAXA is the Mercury Magnetospheric Orbiter (MMO) which will observe the planet’s magnetic field with unprecedented accuracy in an effort to better understand its configuration and how it is being created.  It is hoped that the probe can also reveal how Mercury’s magnetosphere differs from Earth’s.  Since these are the only bodies known to have magnetospheres, it is possible that comparing the two will help us understand  something about both of them.

Another job of the MMO is to observe the tenuous exosphere of Mercury.  Rather than a gaseous atmosphere like Earth’s, Mercury is surrounded by a very thin layer of atoms, mainly sodium, that have been blasted off the surface by the fierce solar radiation and the impacts of micrometeorites.  These atoms quickly heat up and escape into space, so Mercury never builds up as much pressure as Earth’s atmosphere has.  This exosphere has never been studied in detail before, and the MMO will observe its structure and the process of formation and escape into space.

The other component of the BepiColombo mission is the Mercury Planetary Orbiter (MPO), contributed by the European Space Agency.  The function of this probe is to study Mercury as a planet: its form, interior, structure, geology, composition and craters.  This will result in a more accurate and detailed map of Mercury than we have ever had before, as well as a better understanding of just what the planet is made of.

One specific question that will be addressed by the MPO is whether there is frozen water at Mercury’s poles.  In the flyby of Mariner 10 back in 1974, the satellite received radar reflections from the polar regions, so we know that there’s something highly reflective there.  Nature doesn’t produce many things that are that reflective; frozen water is the most common.  And it makes sense, because there are areas at Mercury’s poles that are permanently shaded, and probably have been been since the planet was formed.  As strange as it seems, the closest planet to the sun has places that have never felt sunlight, and may be the coldest piece of ground in the solar system.  The MPO will subject these areas to closer scrutiny, looking for ice.

Like some other places in the solar system, Mercury is interesting because it can tell us something about the system’s early times.  On Earth, any substances that we find have been crushed, melted, reformed, eroded and then reformed again, possibly many times over.  There really isn’t much pristine matter from the solar system’s birth for us to study here.   On some of the other bodies in the system, there may be more unchanged matter that can give us a better picture of the original accretion disc which gave birth to all of this.  In particular, if there is ice at the Mercurian poles, it may be a sample of the water vapor that was present in that disc around the sun, which froze in those early times and has remained frozen ever since.  As you can imagine, the planetary scientists are itching to get a peek at it.

The questions are there, just waiting to be answered- and BepiColombo will bring us some of those answers.  By the time it arrives in 2020, we should already have a lot of new information on Mercury from NASA’s MESSENGER probe, which will have been in orbit around the planet for nine years.  BepiColombo will fill in more of the gaps in our knowledge, providing us with our most complete picture yet of the sun’s first planet.    The projected mission is only supposed to last for one Earth year, but there is the possibility of an extension beyond that.

BepiColombo is a big, ambitious mission with huge potential.  It is a remarkable technical achievement, and in the coming years it will bring us some fascinating science about one of the last unexplored bodies in our system.

The fun is just beginning!  As the news comes in, you get always get it here.

Sources:
Mercury Exploration Mission “BepiColombo” at website of Japan Aerospace Exploration Agency:  jaxa.jp/projects/sat/bepi/index_e.html

BepiColombo page at website of the European Space Agency:  sci.esa.int/science-e/www/area/index.cfm?fareaid=30

BepiColombo Overview on the Science and Technology page at website of the European Space Agency:  esa.int/esaSC/120391_index_0_m.html

World Book at NASA- Mercury:  nasa.gov/worldbook/mercury_worldbook.html

Mercury: Closest Planet to the Sun at website of National Geographic:  science.nationalgeographic.com/science/space/solar-system/mercury-article.html

BepiColombo: Mercury Interior at website of the European Space Agency:  sci.esa.int/science-e/www/object/index.cfm?fobjectid=31272

For space kids who grew up reading science fiction, this idea requires no explanation.  For those unfortunate readers who did not have this experience, we offer this quick summary:

The warm, gentle sunlight that we feel here on Earth is really only a tiny fraction of the sun’s full output.  Even the hottest places on Earth- say, Death Valley or the Sahara Desert- are only receiving a small percentage of the solar radiation that hits the atmosphere above them.  Luckily for us, we are protected from most of it by that thick blanket of air.  Outside of that protection, the wind from the sun is a blasting torrent, a constant tsunami of radiation and particles.

And of course, sunlight exerts a certain amount of pressure.  The pressure is very weak down here on Earth, but if you get off the Earth and move into the full blast of the solar wind, everything changes.  Suddenly you’re in the full tsunami, and the pressure exerted by it is much greater.

Consider what you’ve got here.  It’s a stream of propulsive force which, in human terms, is inexhaustible- and unlike the intermittent thrust of rockets, this is constant propulsion, which allows you to build up enormous speed over time.  In the world of space exploration, this is the Holy Grail.  It is the thing that can finally free us from that necessary evil of space flight: fuel.  The sad fact is that when you’re using conventional rockets, the fuel is the biggest part of the weight.

Now, we’ll always need a big push to get out of the atmosphere and attain orbital velocity, and chemical rockets are still the only way to get that (though other ideas have been discussed- more on this in future articles).  However, once you get into orbit and you’ve got all that sunlight,  why not use it?  Throw out a kite and ride!

That’s the definition of a lightsail: a kite that uses the solar wind to move a spacecraft.  In the old days, this was pure sci-fi, because we didn’t have any materials that were strong and light enough to do the job, but recent advances in materials science have provided lightweight plastics that are bringing the goal within reach.   Not only that, but we now have a couple of possible embellishments that build on the basic concept and use the power of light in different ways.

As mentioned above, there are actual prototypes being readied for launch this year.  The Japan Aerospace Exploration Agency, a rising power in the field of space exploration, is planning to send up a craft called IKAROS in May.  In an effort to cut costs, the craft will be launched aboard the same rocket with Japan’s Venus Climate Orbiter, the partner to the European Space Agency’s Venus Express which we discussed a few weeks ago.

IKAROS takes the idea of a lightsail a step or two further.  Here, the plastic membrane is not only used for propulsion, but also contains three other systems: a thin-film electrical power generation system, a set of steering devices and a dust-counter.  They do all this on a layer of polyimide that is only .0075 mm thick.  When fully deployed, IKAROS will be a square with a diagonal length of 20 m.  Its mission will be in two stages.  In the first stage, the sail will be deployed and used to generate electricity.  This will be the first time a lightsail has been used for this purpose, and if the mission ended right there, it would have already started a revolution in the field of space electronics.

But hopefully, IKAROS will keep on going.  The second phase of its mission is to actually use solar power to navigate the craft.   The destination of IKAROS is uncertain, but it will be steered toward Venus.  As mentioned above, it will be sent into orbit on the same rocket with the Venus Climate Orbiter, and hopefully both craft will eventually arrive at that planet.

IKAROS is the first of two proposed Japanese missions.  The second one will take place in the late 2010′s, and will consist of a hybrid craft which combines all of the technology of IKAROS with an ion propulsion system.

The ion drive uses electricity generated by solar power to excite xenon fuel.  The excited fuel is focused into a jet by passing it between two powerful magnetic fields, and leaves the engine at high velocity.  The advantage of an ion engine is that the xenon fuel is capable of delivering a large amount of thrust in proportion to its weight, which means that a spacecraft can carry enough fuel to keep going for years.

When you combine this system with the lightsail idea, you get a hybrid craft that can use both systems to maximum advantage.   For instance, such a craft might use its lightsail while it’s near the sun, riding the solar wind and storing up electricity.  Later, when it gets farther out where the sunlight is weaker, it might fold up its sail and use the stored electricity to run the ion drive.

Here in the US, the Planetary Society is making its second attempt at testing a lightsail.  Their first one, Cosmos I, was tragically lost when its launch rocket crashed, but now the Society has embarked on an ambitious project to deploy three sails over the next few years.   While the Japanese project is focused on broad technologies that will be used for multiple projects in the future, the Planetary Society is focusing more on practical and specific jobs, such as monitoring the sun for solar storms and providing stable Earth observation platforms.

Their first sail, Lightsail I, will be launched this year and will demonstrate the deployment of the sail and its use for propulsion.  The second sail will do the same, but will move to a much higher Earth orbit.  The third sail in the Planetary Society’s program will leave Earth orbit and navigate to the Earth-Sun libration point, L1.  This will be an ideal location for weather-sensing satellites and other devices, which in the future will hopefully be propelled into their positions by lightsails.

The Planetary Society’s ambitions are set on greater goals someday.  Louis Friedman, the Society’s executive director, recently posted an article on their website about the glowing possibilities offered by this line of research.  One possibility that he brought up is the idea of using a lightsail with an Earth-based laser for propulsion instead of sunlight.  With something like that, you could send a beam of coherent light at another star and ride it all the way there.  When you arrived, you could set up another laser and point it back at Earth, then ride the beam back home.  Whereas the basic solar sail idea only allows travel within the solar system, the laser idea could give us access to the stars.

It’s a long way off, but someday it could happen.  In the meantime, we need to do the basic groundwork, and that’s what’s about to happen.  Both the JAXA craft and Lightsail 1 will go up this year, and the results of those projects will show the way to the future.

In 1964, Arthur C. Clarke wrote a short story called “The Sunjammer,” which was about a race between solar-propelled spacecraft.  It was published in a popular boys’ magazine, and was read by a whole generation of kids in love with space.  Some of those kids are probably working on these projects today- and some of them are also reading and writing about them.

Stick with us, and you won’t miss a thing.

Sources:
Satellites and Spacecraft: Small Solar Power Sail Demonstrator “IKAROS” at JAXA website:  jaxa.jp/projects/sat/ikaros/index_e.html

IKAROS Project page at JAXA website: jspec.jaxa.jp/e/activity/ikaros.html

Let’s Set Sail for the Solar System by a Solar Yacht!  at JSPEC website: jspec.jaxa.jp/ikaros_cam/e/03.html

Lightsail- the Future of Solar Sailing at the Planetary Society website:  planetary.org/programs/projects/solar_sailing/

Friedman, Louis D.: Lightsail: A New Way and a New Chance to Fly on Light at the Planetary Society website:  planetary.org/programs/projects/solar_sailing/tpr_lightsail.html

The Sunrise telescope is a collaborative project between the Max Planck Institute for Solar System Research (MPS) and a number of partners based in the USA, Spain, Sweden and Germany.  These partners include research facilities such as NASA’s Columbia Scientific Ballooning Facility, the ESRANGE Space Centre in Sweden and the High Altitude Observatory in Colorado. The aim of the mission was to launch a telescope into space which could provide high-resolution images of the Sun’s surface which would assist in studying the magnetic field in the solar atmosphere.

The main instrument for the mission was built by Kayser-Threde under MPS supervision and this comprises a light weight solar telescope of 1m aperture. Other instrumentation includes a spectrograph and magnetograph and with its array of technological features it was expected that the telescope would provide observations of the Sun’s surface which could detect features as small as 30km in diameter. On completion of the telescope a successful test launch was achieved in 2007 and this was followed with the telescope being launched into space from the ESRANGE Space Centre in northern Sweden. The launch date was in June 2009 and a giant helium balloon carried the telescope to an altitude of 37 kilometers above the Earth for a six day period.

While viewing the Sun is possible from the ground, turbulence in the lower atmosphere tends to cause image distortion and by launching the telescope into the stratosphere it was considered that more accurate images could be achieved. At this height the telescope can also view the Sun in ultraviolet light which is not possible on the ground as the ozone layer absorbs this type of light. This was of particular interest to the mission team as variations in solar radiation show up more clearly in ultraviolet light. The telescope was kept aligned for observations by an innovative control system which kept it focused on the Sun during its flight and on completion it detached from the balloon and parachuted safely back to Earth.

While the flight itself took place in June, the results have only started to be released in November and these have shown that the telescope has been a spectacular success. It has provided some stunning images of the surface of the Sun to a level of detail which has never been achieved previously. These show details of the complex interplay that exists on the surface of the Sun and also excellent close ups of the grainy surface structure itself which is known as granulation.

The first views of the results have demonstrated that the telescope is capable of providing information which should help scientists greatly increase our understanding of the Sun and its activity. A total of 1.8 terabytes of data was collected and analysis of this is ongoing. Hopefully as further results are released they will provide ever more impressive details to enhance the study of the Sun and provide a leap forward in our knowledge.

Further flights of the telescope are planned and this will place the Sunrise project at the forefront of solar study. If future flights are as successful as the first then we can expect our understanding of the Sun to move forward in the coming years.

Check out the launch of the Sunrise Telescope below: