It will be a landmark of cooperation between India and Russia in the area of space exploration, just one more example of the new spirit of openness and interaction between nations in this field. If you go to the website of the Indian Space Research Organization and click on “International Cooperation,” you will find a sentence that sums it all up:

“India has always recognised that space has a dimension beyond national considerations, which can only be addressed by international partners.”

Chandrayaan-2 is an excellent example of this post-Cold War attitude. But it is more than just a symbol; this mission will do good science. It will teach us some things about a body that still has a surprising number of questions associated with it: our own satellite.

Your eyebrows may have risen slightly as you read that last line. “What?” you may ask. “Don’t we already know plenty about it? After all, we’ve actually been there! We have moon rocks! What more do we need?”

Well, let’s put it this way: Imagine an alien civilization that has never visited Earth, and wants to know something about it. After great effort and expense, they finally manage to land an expedition on our planet. They hop out, knock a few golf balls around, and gather up a boxful of rocks. Then they go home, and never come back.

Now, how much do you think our hypothetical aliens could learn about our planet from that? Granted, the analogy has some rather large holes in it, since we really can learn a lot about the moon, or any body, just by observing it from afar. Due to recent technological advances, we can now gather quite a bit of information without actually going there.

But no matter how much we learn from a distance, there will always be questions that can only be answered by going there, and a boxful of rocks is only the beginning. That fundamental fact is the rationale behind further exploration of the moon.

For the time being, that exploration can be conducted by our robot probes, which will learn more about the environments of the moon and other bodies in the solar system. Human beings will follow later.

Some of the specific things that we are trying to learn about the moon relate to the ambition of putting permanent bases there, while other things simply have to do with understanding how the moon formed, and what it can tell us about the early days of the solar system. At the moment, we have some really good theories about how the moon came into being. The bad thing about theories is, they don’t mean diddly without some evidence to back them up. Now that we have the theories, we’re trying to get the evidence.

The leading theory about how the moon came into being is that early in the lifetime of our planet, it was struck by a body roughly the size of Mars. (Luckily, there was nothing living here at the time- this was so long ago, even dinosaurs were science fiction.) The resulting cataclysm was beyond our feeble imagining; the entire planet literally reeled from it, and an enormous amount of material was thrown up. While some of this material fell back to Earth, a large portion of it went into orbit, and eventually coalesced into a single body. That body is the moon.

(This is a great oversimplification of this theory, a full discussion of which would keep you reading for weeks. If you want more info, go to the NASA website and search for “Earth’s moon.”)

The scanty evidence that we have- that box of rocks- seems to bear this out. The moon rocks brought back in 1969 all have a lower percentage of iron than Earth rocks do. This makes sense, if you think about it. Iron is one of the heavier substances that would have been thrown up by that ancient impact. In the impact scenario, you would expect the heavier substances to fall back to Earth, while the relatively light ones would achieve orbit and get incorporated into the moon. The result is a rocky body that has less iron than Earth does.

OK, so we’ve got a nice little theory, and we’ve got some evidence that seems to support it. So far, so good— but the truth is, we’ve only got that one box of rocks, and they were all collected from a single place. How do we know they’re typical? Maybe that area was anomalous, and not representative of the entire moon. Besides, the theory just tells us how the moon got started. After that happened, there was a whole process of evolution that transformed a cloud of loose particles into a spherical body. If we could collect samples from many locations all over the moon, from both the surface and from various depths below the surface, then maybe we could learn something about that process.

That box of rocks is starting to look pretty inadequate now, isn’t it? To understand this body and how it got to be like it is today, we need a whole lot more samples and a lot more work. And this stuff isn’t just abstract science. While we’re going to keep exploring the moon by unmanned means for a while yet, we are aiming for a permanent human presence there eventually. We’re talking colonies, not just outposts.

That dream is now a lot closer to reality than it once was, and part of the reason is the first of these Indian moon probes, Chandrayaan-1. As we saw in our earlier article, that spacecraft participated in observations which have shown the presence of minute amounts of water on the lunar surface. This isn’t just frozen water; the molecules are apparently being made by the action of sunlight bombarding hydrogen-rich rocks. This has enormous implications for future colonizing efforts, and the fact that Chandrayaan-1 took part in the observations that revealed it is certainly a feather in the cap of the ISRO. The second probe, Chandrayaan-2, will expand on this knowledge by putting down a lander and collecting some samples. This will be the beginning of the in-depth investigation into the composition and evolution of the moon.

In discussing this mission, it should be noted that things are still in the planning stage, and details are not firm yet. If you go to the ISRO website, you will find several pages relating to this mission, and they all give different projected launch times, ranging from 2011 to 2013. Besides this, the exact equipment to be included in this mission also seems to be uncertain, with some pages saying that there will be one rover, provided by Roscosmos, and other pages saying that there will also be an Indian mini-rover. In some places, the lander/rover are spoken of as if they will be a single unit, while other places talk of them as separate pieces of equipment. When we start looking at projects that are as much as three years away, it’s not surprising that the details are a bit hazy yet. We’ll have to wait a while to get more definite and specific information.

However, there are a few points that are certain. Chandrayaan-2 will be launched from India’s Sriharikota launch facility aboard a Geosynchronous Satellite Launch Vehicle (GSLV). While this is primarily an Indian and Russian collaboration, there will be some instruments provided by NASA and the European Space Agency. Once the orbiter is in orbit around the moon, the lander will detach and land near one of the lunar poles. The rover (at least the larger one) will be designed by Roscosmos, and will be powered by solar panels, possibly augmented by a nuclear power source. The lifetime of this rover will be variable; while some web pages give the projected lifetime as only a month, others say that it may be extended for as much as a year. As with other details of this mission, this one is still uncertain.

Even if the rover is only roving for a short time, it will be able to cover a lot of distance. It has a maximum speed of 360 mph (rough terrain will decrease this, of course) and should be able to visit several different locations, so that a wide variety of dust and rock samples can be collected.

This is a good mission; it will provide us with the kind of basic scientific information that is absolutely necessary for an eventual human presence on the moon. It may also help us to understand how the moon formed in the first place, which relates to the bigger questions of solar research: how did the solar system get here, and what was the process that made it?

The moon landing in 1969 was more a matter of national prestige than a scientific mission: we went to beat the Soviets. This whole mindset, while it may have had some relevance in that long-ago time, seems quaint and silly to us now. When people go to the moon again, it will be for a better reason. That line from the ISRO site said it right- this really is bigger than any single nation. These efforts are for the whole planet, and the whole human race.

Sources:

News October 22, 2008: “Russia and India Start Preparation of the Second Lunar Spacecraft” at the website of Russian Federal Space Agency: federalspace.ru/main.php?id=2&nid=4536&hl=chandrayaan-2

News January 24, 2009: “Exclusive Interview of Anatoly Perminov, Roscosmos Head, for Rossiiskaya Gazeta” at the website of Russian Federal Space Agency: federalspace.ru/main.php?id=2&nid=5263&hl=chandrayaan-2

Press Release November 14, 2007: “India and Russia Sign an Agreement on Chandrayaan-2″ at the website of Indian Space Research Organization: isro.org/pressrelease/scripts/pressreleasein.aspx?Nov14_2007

About ISRO: “Future Programme- Forthcoming Satellites” at the website of Indian Space Research Organization: isro.org/scripts/futureprogramme.aspx?Search=chandrayaan-2

“International Cooperations” at the website of Indian Space Research Organization: isro.org/scripts/internationalcooperations.aspx?Search=chandrayaan-2

Chandrayaan-2 entry at Wikipedia: en.wikipedia.org/wiki/Chandrayaan-2

“Chandrayaan: Lunar Mission by Indian Space Research Organization:” chandrayaan-i.com/index.php/chandrayaan-2.html

Some of the invaders are already there; others are in the planning stages. One project which is currently being planned, and which will hopefully be launched next year, is the ExoMars mission. This is a project of the European Space Agency, with contributions by NASA. Its purpose is to subject Martian soil and rocks to the most precise and detailed tests yet, in an attempt to discover if they contain the chemical signatures of past or present life. ExoMars will involve both an orbiter and a lander, with the most sophisticated and sensitive detection devices ever sent to Mars. If there is anything alive there, or if there ever was, this is the device that could find it.

The search for life on Mars has had its ups and downs. When the Viking landers arrived in 1976, the samples of Martian soil that they collected showed none of the chemical traces that would be left by life. At that point, all of the planetary scientists on Earth let out a collective groan: Mars was a dead planet! For some years these results stood, leading to the prevailing opinion that Mars did not have life now, and probably never had it.

However, the Viking results, and their interpretation, have come under criticism in the intervening years. For one thing, Viking contained three separate tests for signs of life, and while two of them gave negative results, the third one, called the Labeled-Release Experiment, gave ambiguous results that might be indicative of life. Scientists have never gotten very excited about this, because there is a high probability that the results were produced by natural chemical processes unrelated to life- but the fact remains that the three instruments did not produce uniformly negative results. Until further investigations are conducted, it is impossible to say with absolute certainty that Mars is a dead world, and always has been.

When contemplating the Viking results, these objections have also been raised:

Maybe the instruments on the Viking landers just weren’t sensitive enough to pick up faint traces of biological chemicals in the Martian soil. Since then, new devices have been developed which can detect chemicals in amounts of only a few atoms. If instruments like that were used on Mars, the results might be different.

Perhaps the Viking samples just weren’t taken in the right place. There are certain extreme environments on Earth- the Atacama Desert in Chile, for instance- where soil samples might yield the same results, but that doesn’t mean that Earth is a dead planet.

Another interesting point is that since Viking, we have learned that life is more versatile than we used to think. Extremophile organisms have turned up in places on Earth that are at least as hostile as the environment of Mars. They have been found in places of extreme heat and cold, in permanent darkness, and in chemical environments that would kill most other life. They have even been found encased in rock, where they apparently live by metabolizing the very rock itself. If life can exist in those places, why not on Mars?

A third point, which could invalidate the Viking results, is that even if the chemical signatures of life are not detectable on the surface of Mars, they might be found just underground. Maybe they were present on the surface at one time, but have since been broken down by the harsh UV radiation of the sun, or by oxidation. In that case, they might not be detectable unless you take a sample from underground, or from the inside of rocks.

ExoMars will attempt to address these issues. The lander will be equipped with a drill that can penetrate up to two meters of soil or rock. Samples from that deep should be safe from the both the sun’s UV rays and the effects of oxidation.

The drill is actually three devices in one: a drill, a sample collector and an infrared spectrometer. Once it drills below the Martian surface, it can actually perform spectroscopic analysis within the bore hole. If it spots something that looks interesting, there is a chamber within the drill shaft with an internal shutter which can be used to get a sample.

However, once the sample is taken, the next challenge is to figure out what we’ve got. One problem in identifying primitive organisms, even on Earth, is that they are so simple that their remains can be mistaken for non-living mineral precipitates. Because of this, a visual examination, even on a microscopic level, probably will not be enough to be conclusive. In fact, given the extreme importance of this evaluation, it is likely that no single piece of evidence will be enough to convince all scientists. Therefore, the ExoMars lander will employ several different lines of investigation in determining if a sample contains evidence of life,
including geological and environmental investigations to evaluate possible habitats, visual examination of samples (morphology) and spectrochemical composition analyses.

One of the indicators of life that ExoMars will look for is homochirality. This is based on the fact that two of the main chemicals involved in making life, amino acids and sugars, can exist in left- and right-handed forms which are mirror images of each other. Amino acids and sugars can be created by non-living processes, but when that happens, the resulting substances are split evenly between the two forms. However, living organisms on Earth all use one form or the other- left-handed for amino acids and right-handed for sugars. This is necessary so that the molecules can fit into the biochemical mechanisms of living organisms. If an amino acid or a sugar is of the wrong form, it won’t fit, and the organism can’t use it.

So, if ExoMars finds amino acids or sugars on Mars, and the chirality is evenly split between right-handed and left-handed forms, we will know that the chemicals were made by some non-living chemical process. But if samples are found which have sugar or amino acids that are all left- or right-handed, it will be a conclusive sign that the chemicals were created by biological processes.

To conduct these chemical studies, ExoMars will use an instrument called the Urey Mars Organic and Oxidant Detector (named for Dr. Harold Urey, biochemist at the University of Chicago). This device uses several flat surfaces coated with chemical films, which are attached to each other to form a box. When a sample is placed in the box, the degree of reaction on each surface will be monitored, and this will tell us if there are any biochemicals present.

Besides the basic search for biochemicals, ExoMars will also be trying to spot potential problems for future human explorers. For instance, are there corrosive substances on Mars that could degrade equipment, or cause health hazards for humans? And what about the Martian dust? When astronauts went to the moon, the moondust got into everything, even in places that were supposedly sealed airtight. If that’s going to happen on Mars, we need to know about it ahead of time, and take measures to prevent it.

ExoMars is a big step forward in our journey to the red planet. It will tell us what Mars used to be like, and it may even find the signs of life, past or present. It will also tell us what we can expect there, and what we will have to do to survive. ExoMars and its mechanical brethren are paving the way for us, and the information it obtains may be crucial in the survival and prosperity of future colonies.

In addition to that, ExoMars is looking back into the past of Mars. It is now well established that Mars looked a lot more like Earth at one time: there were large bodies of liquid water, and that means that the air pressure was much higher than it is today. We can’t help but wonder: just how similar was it? Was there life, and did it look like us?

The answers are waiting on the red planet, and ExoMars is going to help us find them.

Sources:
NASA Science Missions: ExoMars Urey Instrument at the NASA website: science.nasa.gov/missions/exomars/

Mars Oxidant Instrument at the NASA website: nasa.gov/centers/ames/multimedia/images/2007/moi.html

“Sensor Being Developed to Check for Life on Mars” at the NASA website: nasa.gov/centers/ames/research/2007/mars_sensor.html

ESA Aurora Program: ExoMars at the webiste of the European Space Agency: esa.int/esaMI/Aurora/SEM1NVZKQAD_0.html

“ExoMars: Searching for Life on the Red Planet” (information packet downloaded from ESA website)

In one of our earlier articles, still posted here, we took a look at the European Space Agency’s Venus Express probe, which is already in orbit around Venus.  These two projects are not redundant, nor are they in competition with each other.  The projects have been in close communication with each other since their beginning phases, and have been planned to complement each other in the construction of the most complete picture possible of the Venusian environment.  In some cases, the two Venus probes will work together on composite science projects, while in other cases, they will be doing separate work of a complementary nature.

The Venus Climate Orbiter, also called Akatsuki, will weigh 480 kg. with fuel, and will carry a science payload of 34 kg.  Basically, it will be a rectangular box with “paddle wheel” solar panels extending on either side.  There will be small thrusters at all eight of the corners for minor attitude adjustments, and a larger engine for orbital maneuvering in the rear of the unit.  There will be five instruments onboard, taking observations at different wavelengths to obtain various types of information.

Departing from Earth in May of this year, Akatsuki will first deploy all of its secondary payloads.  These include some experiments proposed by prominent Japanese universities relating to information encoding and transmission, observation of the Earth’s atmosphere for meteorological purposes, and the testing of computer technology for space use.  The last of the secondary payloads to be deployed will be the IKAROS lightsail, an exciting experiment to test the use of the pressure of sunlight to propel a spacecraft.  (See our article on lightsails at this site.)  On the journey to Venus, Akatsuki use the travel time to perform various astronomical observations and to study the interplanetary dust cloud.

Akatsuki will arrive at Venus in December 2010 and settle into a long, elliptical orbit near the planet’s equatorial plane.  This will be a 30-hour orbit in a westward direction.  The apoapsis (farthest point from the primary) will be 79,000 km., and the periapsis (nearest point to the primary) will be 300 km.  Global images of the atmosphere and the ground surface will be taken every two hours continuously.  Because of its stretched-out orbit, the probe will be making close-up observations of mid-scale features at periapsis, and more long-range observations at apoapsis.  It will take advantage of periods when it is in the planet’s shadow to make low-light studies of phenomena such as lightning and air-glow.  (Lightning has never been observed on Venus, and there is some question as to whether it even exists there at all.  Scientists will be eagerly waiting to see if Akatsuki spots any.)

Akatsuki is being called an “interplanetary meteorology” mission, because its main function is to peer deep into Venus’ murky cloud cover and obtain 3-D images of the phenomena happening there.  It is hoped that the probe will be able to see the different layers of the atmosphere, how they are moving, and how they interact with each other and with the planet’s surface.

The whole purpose is to try and understand the amazing movement of the Venusian atmosphere.  As we saw in our article on the European Space Agency’s Venus Express probe, the big mystery about this planet that has emerged in recent years is that the entire atmosphere is racing around the globe in a planet-wide gale that moves at 60 times the rate of the planet’s rotation.  If you were unlucky enough to be standing on the surface of Venus, you would literally be knocked flat by a non-stop wind of 100 meters per second.  This is called “super-rotation,” and it is a complete mystery.  There is nothing in our Terrestrial meteorology to explain such rapid motion of an entire planet’s atmosphere.  Where is all that energy coming from?  Granted, Venus is close to the sun and has an average temperature of 460 degrees C both day and night, but even that isn’t enough to explain this amazing movement of air.

In some ways, Venus and Earth are very similar.  They are small, rocky planets with roughly the same mass, and it makes sense to think that they should be fairly similar.  The weird thing is, they’re not.  These two planets have taken very different paths in their evolution, and ended up in very different states.  In contrast to our own pleasant world, Venus is a pressure-cooker with a carbon dioxide atmosphere of enormous density.  And now we learn about this super-rotation, and the mystery deepens.  We certainly don’t have anything like that here at home.  How did these two planets, which probably started out as very similar little pebbles in the beginning, end up so completely different?

And as we saw in our Venus Express article, there is another factor that makes the whole thing even more intriguing.  There now seems to be convincing evidence that there are continent-size masses of granite on Venus.  Granite only forms in the presence of water, but due to the heat and pressure, liquid water can’t even exist on Venus today.   If there’s so much granite on Venus, there must have been an awful lot of water there at one time, and that implies a different environment from what we see now.   It must have been an environment with much lower air pressure and much lower temperatures- a planet more like Earth, in fact.

Just how much like Earth?  We don’t know yet, but it is that central question, and other questions connected to it, that will dominate Venusian research in the coming years.  And this thing with the super-rotation has to do with that, because it is very unlikely that this movement of the air was happening with such energy in the earlier, more Earth-like world we’re thinking of. When did it start, and why?  Why does it continue, with no obvious source of energy?  For that matter, why did the whole environment change from a world with water and granite continents into the oven-like place we see today?

Venus is turning out to be a big box of questions, and so far, we don’t have many answers.  However, there is an ominous note in all this: while there are many things we don’t know about Venus, we do know why it is so hot.  The cause of its 460-degree heat is runaway global warming caused by carbon dioxide buildup in the air.  This probably doesn’t result from the same source as our global warming here on Earth.  Since we have absolutely no evidence that Venus ever supported an industrial society, it is far more likely that its carbon dioxide buildup is the result of some natural process.  What process, we don’t know.  Could it happen here?  Of course it could- but will it?  We don’t know, but perhaps it would be prudent to find out.  When you think of it that way, this line of research suddenly becomes more than just an academic question.

If we imagine this ancient Venus, so different from the one we see today, we are tempted to think of a place very much like Earth: balmy islands with palm trees swaying in the breeze.  In all likelihood, this view only shows our provinciality, the fact that we only know one planet.  If there is anything that our study of Venus has already taught us, it is just how different two similar planets can be.  Whatever Venus was like in that long-ago age, it probably wasn’t just like Earth.

As for what it really was like, we will have to guess for the moment.  However, someday in the not-too-distant future, landers will descend to the surface of Venus and start taking samples of the soil and rocks.  At that point, we will finally begin to unravel the evolution of this planet.  If it turns out that those ancient oceans really did exist, perhaps we will find the fossilized remains of things that swam in them.

Between now and then, smaller revelations will be coming out, some of them perhaps in the near future.  When that happens, you can read about it here.

Sources:

Akatsuki Special Site at the website of the Japan Aerospace Exploration Agency:  jaxa.jp/countdown/f17/index_e.html

“JAXA Explores the Planets of the Solar System- Anticipating Amazing Discoveries” at the website of Japan Aerospace Exploration Agency:  jaxa.jp/article/special/explore/imamura02_e.html

“Satellites and Spacecraft- Venus Climate Orbiter ‘Akatsuki’” at website of the Japan Aerospace Exploration Agency:  jaxa.jp/projects/sat/planet_c/index_e.html

“Akatsuki- Planet C” at website of the Institute of Space and Astronautical Science:  isas.jaxa.jp/e/enterp/missions/planet-c/index.shtml

In our last article, we took a look at NASA’s JEO and the main object of its observations, the intriguing moon Europa.  In this article, we will look at the ESA’s JGO, which will orbit Jupiter’s largest moon, Ganymede.

As we said above, the opening of the mission, upon arrival at Jupiter, is a collaborative overview of the entire Jovian system.  Because of its enormous gravity pull and magnetic field, the great planet has a big influence over its satellites, and the system must be viewed as a whole.  In particular, the magnetic interaction between all of these bodies is very complex, and will be studied in great detail.

In connection with this, there will be a contribution from the Japan Aerospace Exploration Agency.  JAXA is designing and building a probe called the Jupiter Magnetospheric Orbiter (JMO), which will perform some stand-alone observations of the Jovian magnetic environment, as well as collaborating with the JGO and JEO on multi-point measurements of Jupiter’s magnetic field and its interaction with its satellites.

So far, we haven’t mentioned the JMO because it will travel onboard the JGO until insertion into Jupiter orbit.  At that time, it will be deployed from the JGO and enter a separate orbit.

The Jupiter Magnetospheric Orbiter will be a spinning probe weighing about 400 kg., and it will be carrying a scientific payload of 25 kg.  When it is deployed, the spin axis will be tilted toward Earth.  This craft will employ technology borrowed from three earlier missions: the Nozomi Mars probe, the BepiColombo Mercury probe and the Solar Sail project.  (The BepiColombo and Solar Sail missions were mentioned in earlier articles at this website.  Nozomi was a Japanese unmanned Mars probe which was unfortunately lost due to technical problems, but its failure had nothing to do with the technology that will be recycled for use on the JMO.)  For its post-deployment maneuvers, it will be carrying 60 kg. of propellant.  For all of its other functions, it will be powered by electricity from two “paddle-wheel” solar panels.

(This info comes from the original mission proposal, and may change before completion.  In particular, the proposal expressed the wish to increase the payload weight.  Hopefully they will be successful in this.)

The JMO has an ambitious schedule of observations to make after being deployed from the JGO.  It will perform the first complete survey of the Jovian magnetosphere, mapping lines of magnetic force which run from Jupiter to its moons.  It will also address various questions relating to the interaction of the solar wind with the Jovian magnetosphere, as well as the effects of these interactions on the atmosphere of Jupiter.  As mentioned above, there will be some studies which will be performed in coordination with the JGO and JEO.  The presence of a third point of observation will allow the construction of three-dimensional images of the magnetosphere.

After separating from the JMO, the JGO will first take part in an elaborate series of maneuvers in coordination with the JEO, in which they will conduct a large-scale survey of Jupiter and its moon system.  The JGO’s primary goal is to study the moon Ganymede, but there will also be observations of Callisto, Io and Europa, performed either alone or in cooperation with the JEO.  After that, the JGO will go into orbit around Ganymede for prolonged observations.  (This is a greatly simplified description.  The full itinerary will include an ambitious- and confusing- array of maneuvers, a full discussion of which is far beyond the scope of this humble article.  For those who want more details, the websites of all three space agencies offer fascinating reading.)

Ganymede is Jupiter’s largest moon.  In fact, if this body orbited the sun instead of Jupiter, it would be classified as a planet.  It is larger than either Mercury or Pluto, and is three-quarters of the size of Mars.  It actually has an oxygen atmosphere, though the pressure is too low to support any kind of life known on Earth.

One interesting point about Ganymede, and the subject of some of the study on this mission, is that it is the only moon in the solar system with an active magnetic field.  Like so many other things in the Jupiter system, Ganymede’s magnetism is a result of Jupiter’s gravity.  In our last article, we saw that the big planet’s gravity causes tidal heating in the interiors of its moons, especially the closer ones.  This is the reason why Europa almost certainly has a liquid ocean beneath its surface, and it is also the reason for Io’s excessive volcanic activity.  Here we see another example, for without Jupiter’s gravity, Ganymede would not have its magnetic field.

As we saw in our article on the BepiColombo Mercury probe a couple of weeks ago, a body can only have an active magnetic field if it has a solid inner core with a molten mantle above it.  The molten mantle contains iron, and the heat which keeps it molten causes it to move in convection currents.  The solid core contains iron, too, and the movement of the molten iron mantle around the solid iron core is what makes the electrical current that forms the magnetic field.  Without this movement of iron around iron, electricity will not be generated, and the body will not have a magnetic field.  In the case of Ganymede, it is the tidal heating caused by Jupiter’s gravity that keeps the moon’s mantle liquid, allowing the convection movement that makes the whole process work.

During the time when the JGO is orbiting Ganymede, there will be times when the JEO is also passing close enough to allow coordinated observations involving both probes.  This will allow detailed study, with the JGO performing close study while the JEO observes from farther away.  In this way, it is hoped that they will be able to do precise mapping of the Ganymedan magnetic field.

We already know that Ganymede’s history has been long and complicated.  About forty percent of its surface is highly cratered, darker areas, while the other sixty percent is lighter in color, and is covered by an elaborate pattern of grooves.  The surface of Ganymede is mostly water ice, and these grooves are thought to be caused by tensional faulting of this ice, or by liquid water flowing up from below the surface.  Here, as on Europa, we have the near certainty of large amounts of liquid water beneath the surface.   The presence of liquid water always raises the possibility of life, and here again we get back to the main goal of the entire EJSM/LaPlace mission,  to search for habitable worlds.  This actually encompasses two separate questions: do these worlds have life now, and could they support human beings in the future?

The fourth moon to be examined will be Callisto, and these observations will be conducted primarily by the JGO, though the JEO will take part in some of them.  Callisto is the third largest moon in the solar system, and is almost as big as Mercury.  The unique and interesting thing about Callisto is that it seems to be a geologically dead world, with no visible seismic activity, vulcanism, or anything else to alter its surface.   Unlike the three other moons we have looked at, this one orbits much farther from Jupiter, so the kind of volcanic activity that we saw on Io, for example, is absent here.  Because of this, it is thought that Callisto has the oldest landscape in the solar system, preserving impact craters from the very early history of planetary formation.  All of the other bodies in the solar system have changed since then, but Callisto remains as a snapshot of the system’s childhood.  As you can imagine, this moon will be the subject of much study in the future, and the work that will be done by this mission will pave the way for that research by giving us our first close-up view of the body.

The EJSM/LaPlace mission is a huge undertaking which promises to yield a staggering amount of data.  Even if some of the science doesn’t come off as planned, this project will undoubtedly be one of the most productive and thorough space projects ever.  For years to come, we will be poring over the information that this project will give us.

We have always had our eyes on the moons of Jupiter.  Ever since Galileo looked through his homemade telescope and drew his first crude pictures of them, we have wanted to visit them.  The more we learn about them, the more interesting they get.  These are real worlds, with atmospheres, heat and water.  They may have life, and they certainly will have it in the future, for we will visit these bodies in person someday.  While it is unlikely that hellish Io will ever be settled by humans, it certainly makes an interesting place to study, and the other three Galilean moons will almost certainly feel the tread of human feet someday.  When that happens, it will be a direct result of the knowledge we gain from this mission.

Sources:

Solar System Exploration: Moons and Planets of the Solar System at NASA website:  solarsystem.jpl.nasa.gov/planets/

OPFM: Outer Planet Flagship Mission at website of Jet Propulsion Laboratory, California Institute of Technology:  opfm.jpl.nasa.gov/europajupitersystemmissionejsm/

OPFM: Outer Planet Flagship Mission- Jupiter Ganymede Orbiter (JGO) Concept at website of Jet Propulsion Laboratory, California Institute of Technology:  opfm.jpl.nasa.gov/europajupitersystemmissionejsm/jupiterganymedeorbiterjgoconcept/

Synergy Between JMO, JGO, and JMO at ISAS/JAXA website:  sprg.isas.jaxa.jp/jupiter/pukiwiki/index.php?Synergy%20between%20JMO%2C%20JGO%2C%20and%20JEO

Scope and Purpose: The Europa Jupiter System Mission (EJSM) at ISAS/JAXA website:  sprg.isas.jaxa.jp/jupiter/pukiwiki/index.php?I.%20SCOPE%20and%20PURPOSE

III “The Spacecraft” and III.1: “Current Plan” at ISAS/JAXA website:  sprg.isas.jaxa.jp/jupiter/pukiwiki/index.php?III.%20Spacecraft

II.2.1 “Main Objectives” at ISAS/JAXA website:  sprg.isas.jaxa.jp/jupiter/pukiwiki/index.php?II.2%20Magnetospheric%20and%20Space%20Sciences

IV.1 “The Current JAXA Plan” at ISAS/JAXA website:  sprg.isas.jaxa.jp/jupiter/pukiwiki/index.php?IV.%20Orbit%20and%20Operation

The two main spacecraft in the mission are NASA’s Jupiter Europa Orbiter (JEO) and the European Space Agency’s Jupiter-Ganymede Orbiter (JGO).  While the exact timeline has yet to be released, tentative plans would have the two crafts being launched about a month apart.  They will travel for about six years, and for a while after reaching Jupiter, they will work together.  The first part of the mission is an elaborate dance through the Jupiter system, collaborating on an overview of the giant planet and its system of satellites, which has been called a mini-solar system because of its size and complexity.   After that, the probes will go into their separate orbits around Europa and Ganymede for in-depth study.  During the course of the mission, there will also be flybys of Io and Callisto.

Because this mission is so big, and since it involves two spacecraft, we will divide it into two segments.  In this part, we will look at NASA’s Jupiter Europa Orbiter.  As the plan stands now, this probe will launch in February 2020 aboard an Atlas V 551 rocket.   The course that it will follow will be called the VEEGA course, since it involves one gravity assist maneuver at Venus and two at Earth.  On this trajectory, it will arrive at the Jupiter system in December 2025.  (Dates may change slightly as plans become firmer.)  After entering orbit around Jupiter, it will undertake a 30-month tour of the Jovian system, which will be followed by Europa Orbital Insertion (EOI) for a nine-month science mapping phase.  There will be several highlights in this tour:

1. Four encounters with the moon Io, with a possible volcanic plume flythrough.

2.  Six Europa encounters before the actual insertion into orbit around that moon.

3. Six encounters with Ganymede, to study that moon’s magnetosphere.

4.  Nine encounters with Callisto.

5.  Continuous monitoring of Jupiter and Io’s atmospheres.

After this, the probe will enter a 200 km. orbit around Europa, conduct a one-month mapping survey, then move to a 100 km. orbit for further observations.

The data collected by the JEO will add to the basic information we already know about this body.  Europa is a little smaller than Earth’s moon.  Like Earth, it is thought to have an iron core, a rocky mantle and an ocean of salt water.  However, this ocean is deep enough to cover the entire surface, and the top layer is frozen solid.  Europa is an ice world, its surface riddled with countless cracks.

When we look at Europa, we see evidence of the dominant theme of the Jupiter system: Jupiter.  The enormous planet influences everything here with its gravity.  It is tidal heating which causes Europa’s inner ocean to be liquid instead of solid, and it is Jupiter’s constant tugging on this water that causes the ice above it to be covered with an elaborate pattern of cracks.

Within that inner ocean, there may be life.  Nature has created a perfect environment for it here, containing both water and heat.  Of course, we won’t really know what’s in there until we can put landers down and take some samples, but the JEO will be doing the basic groundwork that will lead to that.  Using the information that comes from this mission, future missions will know where to go on Europa, and what to look for.  Someday a lander will reach this little world, put a periscope down through the ice, and have a look around.  When that happens, will something be looking back?  We won’t know until we try.

The investigation of Europa will follow the overall purpose of the entire EJSM mission: to assess habitability.  Specifically, does Europa support life, or could it in the future?  To simply ask this question is exciting.  We’re talking about exploration, future colonies and the possibility of extraterrestrial life.  The future is here.

But for now, we’re just trying to get a better idea of all the parts involved, and their relationship to each other.  How big is this layer of liquid water, and how big is the solid core beneath it?  How thick is the ice layer above it, and what are the variations in thickness and composition of this ice over the entire moon?  What is the nature of the surface-ice-ocean exchange?  What are the surface features?  How quickly are they changing?  What are the possible sites for future landings?  These are some of the questions that will be addressed by the JEO.

In addition to its ongoing survey of Europa, the JEO will also perform observations of Io, one of Jupiter’s other moons.  In contrast to Europa, Io is a fire world.  It is the most volcanically active body in the solar system, its surface constantly erupting in an ever-changing array of volcanoes, some of which hurl plumes of matter far into space.  Just as Europa’s inner ocean is the result of Jupiter’s gravity, so is Io’s volcanic activity.  The same tidal heating which melts Europa’s ice is more extreme here, generating enough heat to melt magma.  If there is a volcano conveniently erupting in the right direction when JEO flies by, the probe may be able to fly through the plume and take samples.   Even failing that, we should be able to get some spectrographic data from starlight shining through some of the plumes, and we can expect some wonderful pictures of a world that is about as close to Hell as we’ll ever find.

The lifespan of the JEO is uncertain.  It will eventually impact on Europa when it finally succumbs to radiation damage, or when it runs out of fuel for maneuvers.  By that time, it will have added volumes to our knowledge of the solar system’s biggest planet and its moons.

In our next article, we’ll take a look at the other half of the EJSM/LaPlace mission, the European Space Agency’s Jupiter Ganymede Orbiter.  As we said earlier, this probe will be performing some observations in coordination with the JEO, and will also do some “stand alone” science of its own, orbiting Jupiter’s largest moon while the JEO is orbiting Europa.   Watch for part two!

Sources:

Solar System Exploration: Moons and Planets of the Solar System at NASA website:  solarsystem.jpl.nasa.gov/planets/

Mission News: NASA and ESA Prioritize Outer Planets Missions at NASA website:  nasa.gov/topics/solarsystem/features/20090218.html

OPFM: Outer Planet Flagship Mission at website of Jet Propulsion Laboratory, California Institute of Technology:  opfm.jpl.nasa.gov/europajupitersystemmissionejsm/

OPFM: Outer Planet Flagship Mission- Jupiter/Europa Orbiter (JEO) Concept at website of Jet Propulsion Laboratory, California Institute of Technology:  http://opfm.jpl.nasa.gov/europajupitersystemmissionejsm/jupitereuropaorbiterconcept/

News: LaPlace, Studying the Jovian System at website of the European Space Agency:  esa.int/esaSC/SEMPHEWX3RF_index_0.html

Jupiter: Moons: Europa at website of Jet Propulsion Laboratory, California Institute of Technology:  solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Jup_Europa

Scientists are taking the search for extraterrestrial life to the high seas with two voyages now taking shape in the lab. If everything goes according to plan in about a decade a mission will launch to send a pair of probes to explore the moons of Jupiter. These probes will concentrate on Europa and Ganymede, and they will focus on exploring the oceans that may lurk beneath the surface.

A few years after the mission to the moons of Jupiter launches, an even more ambitious mission will explore the moons of Saturn. This ambitious probe will explore the polar seas thought to lurk beneath the surface of Saturn’s moon Enceladus. The same mission will also explore the seas of Titan, long considered a leading candidate for extraterrestrial life.

These modern missions will use a decidedly old fashioned approach to space exploration ”“ namely a hot air balloon that will hover over the deserts and mountains of the satellites, along with a boat designed to float on an ocean of liquid hydrocarbon.

This unique mission was first announced in February of 2009 as a joint venture of NASA and European Space Agency. Both the mission to Jupiter and the mission to Saturn are now in their critical early planning stages, but once those missions lift off they will provide a unique view of some of the most promising locations in the hunt for extraterrestrial life.

As it stands now the plan is for the Europe Jupiter System Mission, or EISM, to lift off early in 2020. The mission will proceed in two stages, with the NASA sponsored Jupiter Europa Orbiter and the European Space Agency’s Ganymede Orbiter due to be launched within a month of one another. The two spacecrafts will plot a parallel course for Jupiter, taking six years to reach their respective destinations. Once the probes reach the moons of Jupiter they will explore several of the planet’s satellites before each probe moves on to its primary target ”“ Europa and Ganymede respectively.

What makes these probes unique is the fact that they will explore not only the surface of each satellite but the depths of the moons as well. As far back as the Voyager space missions scientists have suspected that the frozen crust of these satellites hides a liquid ocean, and the presence of a liquid ocean could greatly boost the chances that extraterrestrial life is lurking within the confines of our own solar system. While other exploration has focused on the possibility of life on planets orbiting distant stars, these upcoming missions take a much more local approach to the hunt for life beyond the bounds of Earth.

In order to complete their missions the orbiters will be equipped with special radar designed to penetrate the thick polar ice covering the moons of Jupiter and Saturn. If this crust of ice is relatively thin ”“ only a few kilometers ”“ that ice penetrating radar may even be able to peer into the deep ocean beneath the surface. But even if the ice sheet is too thick for direct observation these probes are expected to shed new light on the features of these moons, providing scientists with a wealth of new information that could lead to clues about not only the existence of life but the formation of the solar system.

by beconrad