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

The pictures are in!  The flyby maneuvers of Phobos performed by Mars Express were successful, returning lots of data and some beautiful, clear pictures of the moon.  While details of the radiometric study of Phobos’ density will be coming out later, ESA has already released the pictures showing the proposed landing site for Russia’s Phobos Grunt lander in 2012.  It’s a nice, clear area with a relatively level surface, perfect for a lander.  With this final detail, the Russian mission is set.  Originally scheduled for launch in 2009, the Phobos Grunt mission went through delays and schedule changes, as many space projects do, but now appears to be set for launch next year.  The probe will travel for 11 months, arriving at Phobos in 2012.  When it completes its mission, it will be the longest sample-return mission ever undertaken.

Phobos Grunt is a comprehensive mission to study both Phobos and Mars itself.  It will be conducting studies of Mars, Phobos, and their spatial environment (radiation, plasma, space dust, etc.).  While the return of Phobos surface material will be the tour-de-force, and undoubtedly will be the thing for which the mission is remembered, this is really a larger project regarding Mars and its entire area of space.

The probe will also be carrying a culture of Terrestrial bacteria as a biology experiment.  When the mission successfully returns its samples to Earth, the bacteria will be studied to determine the effects of the long space voyage.

The power for the operation of the probe will be supplied by two rectangular solar panels.  These will be folded down like the eaves of a roof during the voyage to Mars, then deployed in a standard “paddle-wheel” configuration during use.  Between these two panels will be a doughnut-shaped propellant tank, and in the hole of the doughnut will be the rocket that will be used for the return voyage.  This assembly will be connected by eight narrow struts to the ring-shaped landing gear underneath.  Before it is deployed, this entire unit will sit atop a completely separate propulsion system, which will be used for the pre-deployment maneuvers.

Phobos Grunt will go up in the same launcher with Yinghuo-1, China’s first mission to Mars, which will investigate one of the great mysteries of Mars: where did all the water go?  It is now abundantly clear that Mars had much more surface water in its youth than it does today.  The process that deprived Mars of its surface water is still only poorly understood.  Recent findings indicate that some of this water is now locked up in frozen subsurface deposits (see our articles on the Phoenix and Odyssey spacecraft) but exactly how it ended up there, leaving the planet’s seas and river systems dry, is something that will bear much further study.

The origin of Phobos is open to question.  It seems to share surface characteristics with some types of asteroids, which would indicate that it was captured from the nearby asteroid belt.  That scenario is perfectly believable, except for one detail: Phobos orbits Mars in a nearly circular path, exactly on Mars’ equatorial plane.  Now, if this were a random asteroid that had been captured, you would expect its orbit to be random; it probably would not be a perfect circle, and it probably would not be exactly on Mars’ equator.  That kind of symmetry is what we would expect from a body that had been formed along with Mars, in the original planet-forming period of the solar system.  In that case, Mars and its moons could have formed out of one big, spinning glob of dust and gas, and therefore would spin in the same plane.

So with Phobos (and its sister moon, Deimos, too) we see a body that looks like an asteroid, but orbits like something that formed along with Mars.  If it’s an asteroid- or a rubble pile composed of several chunks of asteroidal rock- then it’s hard to explain the orbit.  If it formed along with Mars in the distant birth of the solar system, then it’s hard to explain its surface characteristics.  This is the great enigma that is emerging about the two moons of Mars, and all research regarding them will be aimed at clearing up the question.  We haven’t even looked at Deimos in-depth yet, but when we do, all of the questions that are now being asked about Phobos will also be asked about it.  Where did these moons come from?  Exactly what are they?  In the years to come, we will be trying to find out, and Phobos Grunt will be an attempt to get closer to an answer.

There is also another mystery about Phobos: it just looks funny.  There are long, straight grooves running for many kilometers across its surface, as if it had been sandblasted.  That may be literally what happened: asteroid impacts on Mars in the distant past may have thrown up huge amounts of ejecta, reaching so high that it scored the moon’s surface.  Such asteroid collisions may have happened repeatedly throughout Mars’ early history, and provide us with still another possible origin for the Martian moons: they could be formed out of material thrown up from Mars by early collisions, then scored again and again by the ejecta from later collisions.

Alternatively, it is theorized that these grooves may be long, straight fissures in the underlying rock, into which surface dust has settled.  Phobos Grunt will be taking a closer look at these formations to determine which theory is correct.

Upon arrival in Mars orbit, Phobos Grunt will first study Mars’ magnetosphere and atmosphere, and release the Chinese Yinghuo-1 into Mars orbit.  When these operations are completed, the landing on Phobos will be attempted.  This operation is a bit challenging, simply because of the small size of the target.  Phobos is a rugged little rock about 20 or 30 km. wide (depends on which way you measure it; Phobos isn’t even close to a sphere) and simply hitting it will require some sharpshooting.  Landings on small objects are always a time of uncertainty and anxiety for the crew back on Earth; there are so many things that could go wrong.  If you’re a little off-target, you’ve missed the moon altogether, and if you hit it a bit too hard, you’ve smashed your multi-million-dollar probe.  Assuming that Phobos Grunt can get past this nail-biter, it will arrive on the surface of Phobos and collect its samples.  While the object of the mission is to return the samples to Earth for further study, the probe will be able to do some preliminary work on the spot.

Phobos Grunt will be carrying three instruments contributed by France’s Centre Nationale d’Etudes Spatiale.  One of these is a microscope that can see in visible and infrared wavelengths, which will be used to spot interesting places to collect soil samples.  An identical instrument was used with great success on the Rosetta mission (see article at this site).  The other French instruments are a gas-phase chromatograph and a laser spectrometer, which will be used to determine soil composition.   While the samples returned by Phobos Grunt will undoubtedly be studied for years to come, the preliminary examination by these instruments will give us some idea of what we have, without having to wait for the samples to arrive.

Simply getting the samples is only part of the job; they will then have to be returned to Earth.  The long voyage back will be the easy part.  The real anxiety starts when the ground crew starts to think about reentry.  Getting delicate samples to the ground intact has proven a problem in the past.  For instance, in the return of the samples from the Stardust comet mission (see our article), the sample capsule was damaged during the impact, nearly compromising the samples.  Disaster was narrowly avoided that time, but it’s a safe bet that the Phobos Grunt crew will be thinking about it when they try to bring their probe down.

Hopefully, everything will come out all right, and the Russians will have the world’s first samples of Phobos.  As part of their agreement with France, Roscosmos is sharing the samples with CNES.  Within days or weeks at the most, scientists all over the world will finally be able to learn something about this strange little body.

Even if the sample return is unsuccessful, this mission will give us some data about Mars and its largest satellite that will prove valuable for future researchers.  It’s a neat mission, and the spacecraft is a classy device that will probably be copied for other sample-return missions in the future.

As developments happen, you can read about them here.

For old folks who grew up reading science fiction, this is a wonderful time to be alive. So many of our old dreams are coming true, and others are at least looking more likely than they once did. When reading about the advances of space science in recent years, there is sometimes an odd sense of pride, knowing that we dreamed the right dreams, way back then. Every great advancement of the human race is preceded by mighty dreams, and ours were mighty, indeed.

One of the perennial dreams of old-time science fiction writers was the waterworld, a world completely or mostly covered with water. This type of world was the setting for countless sci-fi stories. Some writers, looking at cloudy Venus, mistakenly thought that this was a waterworld, while others put their hypothetical planet in another system. The waterworld setting allowed the author to pursue a fascinating idea: what if intelligent lifeforms evolved from aquatic organisms rather than from land animals? Many of these old stories were populated by fish people and such.

Well, the fish people may be out there, waiting for us. In 2003, the European Space Agency held a conference called, “Towards Other Earths,” which was attended by more than 200 experts in the budding science of extrasolar planet detection. At this conference, Alain Leger of France’s Institut d’Astrophysique Spatiale presented a report describing a new class of planet that may be awaiting detection. That’s right: it was our old friend, the waterworld.

According to Leger and his research team, such a planet would have roughly six times the mass of Earth, in a sphere twice as wide as our planet. It would have an atmosphere and orbit its primary star at about one AU- the same distance as Earth from the sun. The planet’s entire surface would be covered with liquid water to a depth of about 100 km., 25 times as deep as any of Earth’s oceans.

Recent discoveries right here in the Solar System have shown us that such a body definitely can form. We now know that we have at least two waterworlds in our neighborhood: Uranus and Neptune. Of course, they’re both so far from the sun that the water is frozen, making them iceworlds. But we also now know that planets can migrate closer to their primary stars over billions of years, so a body that formed in the outer reaches of a system can end up much closer to its primary.

We know this, because we have found several examples. Over the last few years, planetary scientists have detected a number of “hot Jupiters” orbiting other stars. They are often even bigger than Jupiter, and orbit their suns more closely than Mercury does. Now, the current science of planetary formation holds that such bodies do not form so close to their suns. Big planets like that form far out in a system, where water can’t exist in liquid form. This is where they start their long migration inward, caused by gravitational interaction with the accretion disc of dust and gas that surrounds their sun.

At some point in the planet’s inward spiral, the ice melts and our iceworld becomes a waterworld. To make the dream a little more pleasant, let’s say that our hypothetical world goes inward just far enough to have a nice, balmy climate, sort of like Hawaii without the islands. Since this migration is happening very gradually over billions of years, there might be a long period where the planet has a climate suitable for the evolution of life-as-we-know-it. In fact, the time might be long enough for life to develop to a considerable degree of complexity. We’re talking fish people!

There is an interesting variation on the waterworld which may exist closer to home. There is mounting evidence that some of the moons of Jupiter and Saturn, including Enceladus, Callisto and Europa, have internal oceans covered with thick layers of ice. This was a surprise, as these bodies are so far from the sun that any water should be frozen- but nature is full of surprises, isn’t it? While future probes will give us confirmation and more details, it now seems that these worlds offer much more opportunity for life than we once thought. Who knows, the fish people may be closer than we think.

Granted, that’s a longshot, but eventually we may encounter many of these planets, and at least some of them may have life. However, this is not a certainty, since these worlds will probably lack a feature that figured prominently in the origin of life on Earth: hydrothermal vents.

Hydrothermal vents, sometimes called “black smokers,” are openings on the ocean floor that are constantly pouring out vast amounts of hot gas and minerals from deep beneath the Earth’s surface. Here on Earth, such formations have proven to be zones of intense biological activity, with a profusion of lifeforms fed by the energy and minerals of the vent. One theory of the origin of life on this planet is that it started at these vents and spread outward from there. But according to the report presented by Alain Leger and his colleagues, hydrothermal vents would not exist on their hypothetical waterworld.

Remember what we’ve got here: a planet that formed originally as an iceworld, then migrated inward and melted. But when it was at a distance from its star that would allow Earthlike temperatures near its surface, all of the ice would not have melted yet. While a layer of liquid water would cover the surface to a depth of about 100 km., there would still be a thick layer of ice below that, and at the center of that would be the planet’s core. That core would be molten- but all that ice on top of it would effectively cap any volcanic vents, sealing in their heat. Of course, if the planet continued its journey inward toward its star, it would eventually reach a point where all of the ice would melt and the volcanic material would come gushing out, but by that time, the surface would be too hot for the kind of life we’re familiar with. So our balmy world with its Hawaii-like climate probably would not have hydrothermal vents; they would still be buried under many kilometers of ice.

Supposing that these vents were the source of life on the primordial Earth, we are left with the question, would life evolve on a planet that doesn’t have them? We don’t know the answer to this, but scientists are hoping that when they find such a planet, life will have taken the more obvious route: evolving on or near the water’s surface and using the planet’s sun for its energy source.

If humans decided to colonize a waterworld, they would have to live in floating communities. The very idea of living on the frozen ocean floor would be preposterous- imagine the pressure of 100 km. of water! We can envision colonies like enormous buoys, tethered by cables to the distant ocean floor. Or perhaps nature will provide convenient platforms in the form of floating plants. The “lily pad” shape has been quite successful on Earth; maybe our planet will have something like that, only bigger. Our colonists could built their settlement on top, and as long as they didn’t cover up too much of the plant’s sunlight-gathering surface, they would be fine.

Living on a world without dry land would, of course, require some new, outside-the-box technology. Obtaining metals on such a planet would be extremely difficult, since a thick layer of ice would cover the rocky core. Mining operations would have to drill through it to get to any metals underneath- a stupendous challenge. Rather than going through all that, our colonists might be able to find a convenient, metal-rich asteroid that they could move into orbit around the planet and mine.

All this is assuming that our colonists come fully prepared. As we unfortunately know, space missions can sometimes go catastrophically wrong. Equipment fails, and crashes happen occasionally. If we imagine a scenario in which colonists crash-landed on a waterworld with only minimal equipment, the challenges would be formidable. Even if nature had provided them with those giant lily pads, these people would have a rough time. Since one of the very few hard substances in their world would be human bone, it is probable that the bones of the dead would be recycled to make tools. We can picture a case in which Granddaddy’s leg bone gets made into a harpoon, then gets passed down the generations as a family heirloom.

(While it is not the purpose of this article to offer book reviews, it should be noted that the novel The Blue World, by noted science fiction writer Jack Vance, is an excellent treatment of some of the ideas expressed here, especially those in the last paragraph.)

We will find waterworlds, sooner or later. Sooner is a distinct possibility; we are reaching the point where our space telescopes could find such a body orbiting another star. The COROT satellite, a collaboration between the ESA and France’s CNES, is sensitive enough to spot a body that small, and determining how much water is on its surface. (See our article on COROT from a few weeks ago.) The discovery of our first waterworlds could be right around the corner.

And what about those fish people? Well, they may sound pretty far-fetched now, but when you consider that our species evolved from a tiny, shrewlike ancestor with a brain smaller than a marble, the idea of fish evolving into intelligent, technological lifeforms sounds quite believable.

Maybe we’ll meet them someday!

Sources:
ESA Space Science: “Searching for the Real Waterworld” at website of the European Space Agency: http://www.esa.int/esaSC/SEMR96XO4HD_index_0.html

ESA Space Science: “How Do ‘Waterworlds’ Form?” at website of the European Space Agency: http://www.esa.int/esaMI/COROT/SEMYM6XO4HD_0.html

NASA News & Features: “Water World? New Discovery Heats Up Search for Life” at the NASA website: http://www.nasa.gov/vision/universe/newworlds/EnceladusWorld.html

In addition to this, Planck is also undertaking a few other observations of nearer things, such as parts of our own Milky Way galaxy.  As the most sensitive instrument of its kind, it can see things with a greater clarity, resolution and range of wavelengths than ever before, and scientists have several targets selected for it.

The rocket that took Planck into space was an Ariane 5, the ESA’s standard launch vehicle.  The launch took place on May 14, 2009, from the ESA spaceport in Kourou, French Guiana.  As a cost-saving measure, Planck was launched along with another probe, the Herschel infrared observatory.  These two probes separated from their launcher soon after reaching space.  Both of them were sent on a course that would eventually lead them to the second Lagrangian point (L2), situated about 1.5 million km. from Earth in the opposite direction from the sun.

These two probes will operate independently of each other, but the science they  do will be complementary.  The Herschel infrared observatory is also an interesting subject, and will be examined further in a future article at this site.  For now, we will concentrate on Planck.

The Planck satellite weighed about 1900 kg. at launch, and has a boxy shape about 4.2 meters on a side.  It is equipped with a 1.5-meter-wide mirror which focuses radiation from the sky and sends it to two detectors known as the Low Frequency Instrument and the High Frequency Instrument.

The Low Frequency Instrument (LFI) performs observations of the microwave sky in the range of frequencies from 27 to 77 GHz.  It is composed of 22 tuned radio receivers which work like the transistors in a radio, amplifying the signal and converting it into a voltage.  The High Frequency Instrument (HFI) performs observations in the range from 84 GHz to 1 THz.  It has 52 bolometric detectors , devices capable of measuring very small amounts of heat energy.  The results from these two instruments are complementary, and go together to form the total mission results.

The instruments are very sensitive to heat, and the probe’s designers had to include a cooling system and various other measures to ensure a stable, low temperature.  In fact, the reason why Planck orbits the sun at the L2 point, rather than orbiting Earth, is that both Earth and the moon give off too much heat.  Planck had to get some distance away from them, or their heat would have spoiled the observations.

Planck is equipped with its own thrusters, and these were used for three course correction maneuvers.  The third of these maneuvers took place on July 2, and injected the probe into its orbit around the L2 point.

Because of the temperature constraint, it was necessary to put the probe through a cooling process before it could go into operation.  The instruments hit their lowest temperature, 0.1K above absolute zero, in the first week of July.  During the cooling period, all of the satellite’s subsystems were also turned on and tested.

Planck was designed to give answers to some of the most fundamental questions in cosmology: how did the universe begin, how did it evolve to the state that it is in today, and how will it evolve in the future?  The Cosmic  Microwave Background  carries information about the processes that took place in those early moments of existence, and by analyzing it, scientists can look through a window in time, to the moment right after creation.

This information takes the form of tiny temperature fluctuations in the CMB, about a millionth of one degree.  This is the equivalent of detecting the body heat of a rabbit sitting on the moon from Earth.

Planck’s first task was the First Light Survey, which was really just a chance to check the sensitivity of the instruments and make sure they could perform as expected.  The scientists were delighted to find that the quality of the data was excellent.

Since then, Planck has been working on its first All-Sky Survey.  This began in mid-August 2009, and is being completed now.  As of mid-March 2010, 98% of the sky had been observed by Planck, and 100% sky coverage is expected by late May 2010.

However, before the raw data can be turned into sky maps of the CMB, it will require a lot of delicate adjustments and careful analysis.  About two years will be need to refine the information and obtain the scientific results.  Even then, the resulting maps will provide decades of work for cosmologists and astrophysicists as they continue to study and analyze them.

One of the things they’ll be looking for will be confirmation of the current theory of how the universe formed.  This is one of those sticky moments in science when the scientific authorities have a theory that explains everything beautifully, but they don’t have a shred of evidence to support it- or to disprove it, for that matter.  The theory is called the inflation model, and the condensed version runs something like this:

(What came before the Big Bang, we have no idea.  All of our theories of the evolution of the universe deal with what happened after that event, and if anything came earlier, we probably will never know about it.)

The universe begins as an extremely small point.  During the first millionth of a second of its existence, it rapidly expands, or “inflates.”  After this initial burst of expansion, it continues to grow at a slower rate, and as it grows, the thermal energy which it contains becomes spread out over a larger area.  This means that the universe cools as it expands.

When the temperature of the universe drops to 1000 GeV (about 10 million million degrees) the natural forces appear: gravity, electromagnetism, and the strong and weak nuclear forces.  Quarks, the things that will form matter, appear and wander freely through the universe. As the universe keeps cooling, these quarks will eventually combine to form protons and neutrons, but it will still be too hot for them to capture electrons and make real elements.  Since electrons aren’t being captured to form atoms, they are free to interact with photons (light particles).  Because of this, a photon can’t travel very far without encountering an electron, and light does not propagate freely.  Because of this, the universe is dark.   It is only after 300,000 years that the universe cools enough to allow protons to capture electrons and form hydrogen atoms, which finally allows light to propagate freely. Light comes to the universe, and that first burst of light is the Cosmic Microwave Background.

Matter begins to form clots due to gravity, and as these clots grow, the universe takes on a more familiar appearance.  Stars form, and these form galaxies.

Fast-forward to today, and we see around us a universe filled with structures.  Galaxies form clusters, clusters form sheets and streamers spanning vast distances.  Where did all the structure come from?  If the universe all expanded out of one tiny point, why isn’t it uniform?  Why is matter gathered in some areas, while it seems to be more diffuse in other places?

The inflation theory explains the elaborate structures in the universe, which result from an uneven distribution of matter, by saying that they are the expansion of tiny variations in the original point from which it all expanded, and the expansion happened so suddenly that those variations were preserved, in vastly greater size, as the unevenness of matter in the universe today.

In other words, there has always been an unevenness in the distribution of matter and energy (as well as dark matter and dark energy).  This goes all the way back to the first instant of expansion, and since the CMB comes from close to the first moment (300,000 years is not very long in universal terms) it should have this unevenness, too.  It should also carry various other information from that early time, which Planck’s instruments can coax from it.  As a snapshot of the universe at a young age, it should have things to tell us about how the universe started, and how it got like it is today.

These are the kind of cosmic questions that Planck was designed to address.  Along the way, it will also do some viewing closer to home.  In fact, just a few days ago, the ESA released spectacular pictures taken by Planck showing filaments of cold dust only a few hundred lightyears away.  In addition to its work relating to the CMB, Planck will be doing studies of this nature, investigating structure and evolution on a galactic scale.

Planck is just getting started, and the clarity and resolution of the data so far promises great things for the future.  The questions that it addresses are of the most fundamental nature: how did it all begin, and how did it get like it is now?  You can’t get more cosmic than that.

As new data comes in from Planck, you can find it here.

Sources:

ESA Space Science: Planck Overview at website of European Space Agency:  esa.int/esaSC/120398_index_0_m.html

ESA Planck homepage at website of European Space Agency:  esa.int/SPECIALS/Planck/index.html

“Planck at a Glance: ESA’s Microwave Observatory” at website of European Space Agency:  esa.int/SPECIALS/Planck/SEMWN20YUFF_0.html

ESA Planck: Science Objectives at website of European Space Agency:  esa.int/SPECIALS/Planck/SEM0P20YUFF_0.html

ESA Planck: Planck Highlights at website of European Space Agency:  esa.int/SPECIALS/Planck/SEMKO20YUFF_0.html

ESA Planck: Instruments at website of European Space Agecny:  esa.int/SPECIALS/Planck/SEMBU20YUFF_0.html

ESA Planck: Launch and Early Operations at website of European Space Agency:  esa.int/SPECIALS/Planck/SEMB030YUFF_0.html

ESA Science and Technology: Planck at website of European Space Agency:  sci.esa.int/science-e/www/area/index.cfm?fareaid=17

ESA News: “Planck Sees Tapestry of Cold Dust” at website of European Space Agency:  esa.int/esaCP/SEMMN9CKP6G_index_0.html

ESA Space Science: “So How Everything Start?— a Timeline for the Universe” at website of European Space Agency:  esa.int/esaSC/SEMC6TS1VED_index_0.html

This is an exciting time.  As we have seen in previous articles, there are a lot of fascinating projects going on right now, with robot probes exploring places in the solar system and beyond.  Places that used to be just names in textbooks are now real places to us, and we are learning more about them all the time.

However, it should never be forgotten that the exploration of the mysterious third planet on which we live can be just as interesting, and of even more vital importance.  To help us understand more, there is now a legion of satellites orbiting Earth to study various aspects of its environment.  Many of these are assessing the consequences of environmental tampering by humans, and finding that those consequences are proceeding at a faster pace than was originally thought.

In assessing the consequences of global warming, one of the indicators that is available to us is the Earth’s ice.  We already know that ice in the polar regions is shrinking to levels unknown in recorded history.  Ships can now sail through places that were completely blocked by ice only a few years ago, but this is only anecdotal evidence, and does not tell us how fast the problem is moving or how far it has already gone.  Before 2000, it was thought that the interiors of the major ice sheets were largely stable.  This was based on data gained by satellite altimetry, but the capability of those satellites to measure change at the margins of ice caps, where most of the change was occurring, was limited by their design. By 2006, new information was emerging which was causing scientists to doubt the stability of the ice caps.  In that year, analysis of radar readings of the Pine Island Glacier in Western Antarctica showed a definite thinning of the ice layer. Data from other satellites, such as ESA’s Envisat, mapped the Earth’s ice and found that annual average Arctic sea ice extent had shrunk by 2.8% per decade since 1978.

But even with that information, we still don’t have the full picture.  To get that, it’s necessary to measure the thickness of the ice.  That’s the only way to get an accurate estimate of the amount of ice that is left, and how quickly it is retreating.

To address this need, CryoSat-2 was designed as part of Earth Explorer, a larger project which addresses key questions regarding the natural processes of our planet, and in some cases, how they are changing in response to the stresses placed on them by human activity.

CryoSat was originally intended to be the first of these probes, not the last.  In one of those terrible disappointments that occasionally happen in space exploration, the first version of CryoSat was lost due to launch failure in October 2005.  The ESA immediately started planning for a relaunch.  Cryosat-2 took four years of preparation, and during that time, the other phases of the Earth Explorer Series proceeded as planned.  While CryoSat was being rebuilt, the GOCE gravity mission and the SMOS water mission were launched successfully, and when CryoSat-2 went up today, it completed the series that it was supposed to start.

Cryosat-2 carries technology to measure changes in two types of ice: the huge sheets covering Greenland and Antarctica, and floating ice in the oceans.  The satellite will travel in a highly inclined polar orbit which will reach 88 degrees latitude north and south, to get maximum coverage of the poles.  Its main instrument is the Synthetic Aperture Interferometer Radar Altimeter (SIRAL).  Radar altimeters used in the past have been designed for use over ocean or land, but SIRAL is the first one to be specifically made for use on ice.

SIRAL has a higher resolution than earlier radar altimeters.  Whereas conventional radar altimeters send out radar pulses that are, on average, 500 microseconds apart, SIRAL send its pulses at intervals of only 50 microseconds.  The onboard data processor can separate the echo into strips which are about 250 m. wide.  Since the interval between bursts is arranged so that the satellite moves forward by 250 m. each time, the strips laid down by successive bursts can be superimposed on each other and averaged to reduce noise.   This is known as the SAR (Synthetic Aperture Radar) mode.

In order to get accurate readings, it is necessary to pinpoint the position of the satellite with great precision.  To accomplish this, CryoSat-2 uses the DORIS (Doppler Orbit and Radio Positioning Integration by Satellite) system.  The satellite’s radio receiver measures the Doppler shift of signals from a network of more than 50 radio transmitters around the globe.  The true accuracy of the reading can only be obtained by processing on the ground, but the raw data provides a usable estimate, good to about half a meter.  The DORIS network has been in use for more than ten years, and has been used for various satellites, including ESA’s Envisat.

This locates the satellite itself, but in addition to this, it is necessary to determine the precise orientation of the baseline of the two antennas that receive the signal.  To obtain this baseline, CryoSat-2 uses the sailor’s old friends, the stars in the sky.  There are three startrackers on the antenna support structure, and each of them takes five pictures per second.  The onboard computer compares the images to a catalogue of star positions.  The orientation of the baseline of the receiving antennas is determined using this positioning data.

Unlike many other Earth-orbiting satellites, CryoSat-2 does not have a sun-synchronous orbit- in other words, it does not orbit in such a way as to receive sunlight all the time.  Instead, the satellite’s path is such that there will be times when Earth is between it and the sun.  This presented some design challenges, as the satellite will regularly be subjected to extreme temperature shifts.  Because of this, it was necessary to insulate the precise instrumentation to maintain optimal operating temperature.

Except for a few valves in the propulsion system, CryoSat-2 has no moving parts at all.  Even the solar panels, rather than being deployable as in most other satellites, are rigidly fixed to the body of the craft, forming the “roof” of the structure.  The lack of moving parts allowed a significant cost savings in the satellite’s manufacture.

Knowledge is our best weapon in the fight against the long-term consequences of global warming.  It is a sad truth that we gained the ability to destroy our world before we learned how to fully assess the damage, so the process went on for years before we realized it.  Now we are in the uncomfortable position of having to measure just how far the process has progressed, and what, if anything, we can do about it.  CryoSat-2 is a new tool for that measurement, and from it, we will gain a new understanding of our planet and its processes.  If we could see the history books of tomorrow, how would they speak of this project, and the other Earth-sensing projects that are going on now?  Will they see this as the beginning of recovery, or just a futile assessment of our hopelessness?  Perhaps these measures will only provide us with a precise gauge of the inevitable end, or perhaps not.  Much environmental damage has already been done, and will not be corrected soon- but the knowledge we gain from CryoSat-2 may help us to lessen the impact, at least.

And it will give us a lot of interesting things to ponder, too.  From it, we may pry a few more secrets from this world on which we have always lived, but which we still do not know very well.  In that sense, this is another fascinating, alien planet to explore, because the things we are learning now are totally new.  It’s all part of our growing knowledge of the mysterious third planet.

Sources:

“Successful Launch for ESA’s CryoSat-2 Ice Satellite” at website of the European Space Agency:  esa.int/esaCP/SEMH5ZZNK7G_index_0.html

“ESA CryoSat: an Earth Explorer” at website of the European Space Agency: esa.int/SPECIALS/Cryosat/SEMHSTOJH4G_0.html

“ESA CryoSat: an Icy Mission” at website of the European Space Agency:  esa.int/SPECIALS/Cryosat/SEMFJ4908BE_0.html

“ESA CryoSat: Earth’s Changing Ice” at website of the European Space Agency:  http://www.esa.int/SPECIALS/Cryosat/SEMQK4908BE_0.html

“ESA CryoSat: Platform” at website of the European Space Agency:  esa.int/SPECIALS/Cryosat/SEMFN4908BE_0.html

“ESA CryoSat: the Instruments” at website of the European Space Agency:  esa.int/SPECIALS/Cryosat/SEMRQ4908BE_0.html

Saturn occupies a special place in astronomy: it is one of the first- or possibly the very first- celestial body to be seen through a telescope. In the history of astronomy, there have been a few moments that have made a sudden and permanent change in the human concept of the universe. Before these moments, we were ignorant; after them, we suddenly knew more, and the difference was great enough to alter our whole idea of the world and our place in it. One such moment was the fateful night, often reenacted in TV documentaries, when Galileo, the famed Italian astronomer, first pointed his homemade telescope at Saturn. His hand-ground lenses were less than perfect; he thought he saw a planet with bulges on its sides, which he compared to ears. It was only later, when better telescopes were used, that it became apparent that this structure was a ring system circling the entire planet.

From those humble beginnings, things have come a long way. The Cassini-Huygens probe might be viewed as a culmination of the work started so long ago by Galileo and the other pioneers of Saturnian study. The name of the mission is a tribute to two others: Christian Huygens (1629-1695) who actually identified Saturn’s rings for what they were and discovered the moon Titan, and Jean-Dominique Cassini (1625-1712) who discovered Saturn’s moons Iapetus, Rhea, Tethys and Dione.

The Cassini spacecraft was designed and built by NASA, while the Huygens lander was a project of the ESA. The two were launched as a single unit aboard a Titan IVB/Centaur rocket from Cape Canaveral, Florida, on October 15, 1997. During its journey, the craft made four gravity-assist maneuvers, in which the gravity of a planet was used to alter the craft’s course. These were at Venus in 1998, Venus again in June 1999, Earth in August 1999 and Jupiter in December 2000. The spacecraft arrived at Saturn in July 2004. In December 2004, at the end of Cassini’s third orbit around Saturn, the Huygens lander was deployed. That craft landed on Titan on January 14, 2005.

The Huygens lander was 2.7 meters wide and consisted of two parts: the Entry Assembly Module and the Descent Module. The Entry Assembly Module contained the equipment to control Huygens after its separation from Cassini and included a bulbous heat shield to protect the delicate inner workings during the descent through Titan’s atmosphere. The Descent Module contained the scientific instruments for studying Titan. The probe used three parachutes in sequence during its descent.

The descent and landing of the Huygens probe was absolutely one of the most spectacular visual experiences in all space exploration. As the lander flew over the landscape, we saw what looked surprisingly like Earth: river systems, deserts, mountains and valleys spread out in an intricate panorama. The landing was successful and the probe survived for several hours, sending back a series of stunning images showing a foggy landscape dotted with rounded boulders.

The Earth-like appearance of Titan was deceptive. Those rivers and lakes, which looked so much like water from above, were actually liquid methane. The boulders that we saw around the lander were actually chunks of water ice, permanently frozen in the -180C cold. These substances behave exactly like the substances we are more familiar with here on Earth. Methane acts just like water does here; it is so plentiful that it condenses out of the atmosphere and forms the rivers and lakes. Hydrocarbon particles form dune-covered deserts just like silica (sand) does here on Earth. All of the oxygen is locked up in the water ice on the ground- which is good, because if there were any free oxygen, it could react with the methane to cause a Titan-wide explosion. There is growing evidence that there may be an ocean of liquid water and ammonia on Titan.

Titan is a big, varied world with much to study. We’ll be trying to figure it all out for a long time to come- and that’s not all. Cassini, still whizzing around Saturn, has returned some other science that has enormous implications in the search for extraterrestrial life. Scientists were electrified when geyser-like plumes were seen shooting from Saturn’s moon, Enceladus. These plumes were coming from thin, parallel cracks on the moon nicknamed “tiger stripes,” and spectroscopic analysis showed that they were rich in organic molecules and water vapor. Since then, there has been additional evidence that, as with Titan, there may be an ocean of liquid water under the surface of Enceladus. (See our article on Enceladus at this site.) Now that we know Enceladus has water and the chemical building blocks of biology, it will be a prime candidate in our search for extraterrestrial life.

Cassini has revealed that the rings of Saturn are not as smooth and serene as they appear. Actually, they are rough neighborhoods where particles large and small collide, and the activity in there is quite complex. This mission has allowed more detailed study of the rings than ever before. Having an observation post within the Saturnian system for a long period of time has allowed scientists to see the rings at different angles of sunlight, allowing unprecedented detail and perspective in the observations.

The moon Iapetus is a strange-looking object, and will bear further study. One side of the moon is white and the other side is black, and there is a monumental bulge around its equator. The reason for the unusual shape and color scheme is unknown, but it’s certainly got the scientists scratching their heads.

There may be faint rings around the moon Rhea; further observation may confirm their existence.

The moons Tethys and Dione are spewing great steams of matter into space, indicating possible volcanic activity. Here again, further investigation is needed.

The original Cassini mission came to an end in 2008, but since the probe is still in fine working order, its tour of duty has been extended through the end of 2010. After that, there may be further extensions. It looks like this is one of those space missions that keeps on and on, long after its projected end. We can expect a lot more from Cassini, and when it is finally done with its work, we will know where the future missions need to go.

Cassini has already provided us with a few signposts for further research. Titan will definitely be visited again, and possibly colonized eventually. Those tiger stripes on Enceladus are getting a lot of scrutiny, and will certainly be a target for landings. Tethys and Dione sound interesting, too; if they have the heat for volcanic activity, there may be liquid water inside them, too. There may be life on or in some of these moons; there surely will be many fascinating things to see. For the time being, Cassini will help us to see them.

If the ghosts of Galileo, Cassini and Huygens can look down on us now, they must be proud.

Sources:
“Cassini-Huygens: Fifth Anniversary of the Landing on Titan” at the website of the European Space Agency: esa.int/SPECIALS/Cassini-Huygens/index.html

“Science and Technology: Cassini-Huygens” at website of the European Space Agency: sci.esa.int/science-e/www/area/index.cfm?fareaid=12

“Cassini Equinox Mission” at NASA website: saturn.jpl.nasa.gov/index.cfm

“Cassini Equinox Mission- News and Features: Cassini Finds Saturn Moons Are Active” at NASA website: saturn.jpl.nasa.gov/news/newsreleases/newsrelease20070614/

“ESA Cassini-Huygens: Titan Virtual Tour” at website of the European Space Agency: esa.int/SPECIALS/Cassini-Huygens/index.html

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 conducting these flybys, the ESA is working in cooperation with ROSCOSMOS, the Russian Federal Space Agency.  Russia is planning to place an unmanned lander on Phobos by 2012 to collect soil samples, and images taken on these flybys will be used to select the landing site.

It is hoped that all of this scrutiny will unlock the secret of this moon’s origin, which is a point of much speculation now.  There are three conflicting theories about this, which we will examine in more detail in a moment, and while the final verdict won’t come out until the actual return of soil samples, these flybys are already filling in some of the blanks in our understanding of this body.

We talked about the Mars Express probe in a previous article (still posted at this site).  This spacecraft was launched by the ESA on June 2, 2003, and arrived at Mars in December of that year.  Since then, it has returned huge amounts of data on the red planet, including many beautiful and striking images of Martian landforms.  One of the accomplishments of this mission has been the detection of methane in some areas of Mars, which may be an indication of some sort of biological activity.  Mars Express has also contributed to the growing body of evidence for frozen water just beneath the Martian surface.

This is not the first time Mars Express has encountered Phobos.  In fact, it’s a regular event for this probe, whose orbit periodically brings it close to the moon.  The folks at ESA call it “Phobos flyby season,” and typically use this time to study the body.  But this time is the closest approach to the moon yet, and will present a chance for more exact measurements than ever before.  The observations will include very precise radiometric readings to determine exactly what the gravity of Phobos is, and how mass is distributed within the body.  This information will be useful to the Russians in planning their lander expedition, and will also address a key fact which has come to light about Phobos: it seems to be hollow.

Well, maybe not completely hollow.  Scientists are estimating that between 25 and 35 percent of Phobos’ interior is empty space.  They have arrived at this conclusion because Phobos simply doesn’t have as much gravity as it should.  The dimensions of this moon are quite well established, so it’s possible to get a rough estimate of how much gravity there should be if the whole body is solid rock.  While the flybys that are happening now will give us our most precise measurement of the moon’s real gravity to date, less precise measurements have already revealed that the gravity of Phobos is much less than it should be.  The conclusion is inescapable: this body doesn’t have as much matter as it seems to have.

This is not as big a mystery as it seems.  In fact, Phobos appears to be a type of body that was predicted before any were actually found, and which now seems to be quite common in the solar system.  Scientists call them “rubble piles,” and that’s exactly what they are.  You see, there are an awful lot of rocks flying around out there, especially in the asteroid belt, which is between the orbits of Mars and Jupiter.  In the early solar system, there were even more of them than there are today.  (Nowadays, the majority of these rocks have already crashed into some larger body, and the asteroids that are left are just the small percentage that have managed to avoid this fate.)

Since all matter exerts some gravitational attraction, every one of those rocks has its own gravity, and when rocks come close to each other, they tend to attract.  If two of these space rocks drift together and stick to each other because of their mutual gravitation, then of course, they’re exerting a stronger gravitational attraction than either one did separately, so they tend to attract still more rocks.  Eventually, if more and more of them come together and stick to each other, you end up with a big mass of rocks loosely held together by gravity.  Of course, they don’t fit together very well, and while they are touching each other in some places, there will also be a lot of gaps.  What you’ve got is a classic rubble pile.

Over millions or billions of years, more rocks will keep hitting this pile, smashing up the outer surface and spraying a lot of asteroid dust around.  Eventually, our rubble pile acquires a coating of this dust which fills in the cracks on the outside of the body, giving the illusion of a solid, unbroken surface.  To an outside observer, there is no obvious sign that this body is not solid- but deep inside, all those gaps are still there.  You wouldn’t suspect a thing unless you measured the body’s gravity, at which point it would become evident that there was an awful lot of empty space inside it.

So, that’s the giveaway: if you find a body that has a much lower gravity pull than it logically should have, you know you’ve got a rubble pile.  We have already found a few of these bodies out there.  For example, it is strongly suspected that Jupiter’s moon, Amalthea, is a rubble pile.

This brings us back to a point mentioned earlier: the fact that there are conflicting theories about the origins of the Martian moons.  One of them is the scenario that we’re looking at here: Mars, being so close to the asteroid belt, has attracted some far-roaming rocks into orbit around itself.  The fact that Phobos- and possibly the other moon, Deimos- is a rubble pile instead of a solid chunk doesn’t really effect this scenario; the rocks may have formed into a pile in the asteroid belt, or after they were captured by Mars.

Another theory about the formation of the Martian moons is that some large body slammed into Mars in the remote past, and Phobos and Deimos are fragments from the collision, thrown off the planet with enough speed to achieve orbit.  If this is the case, it is probable that we won’t know for certain until soil samples can be collected from Mars and both moons, so they can be compared.  If Mars and its moons were originally part of the same body, they should have similar compositions.

However, even if this is the case, it still will not be conclusive, and further research will have to be done to get a definitive answer.  If Mars and its moons are made of similar stuff, there is another possible explanation for it, and this gets to the third theory about the formation of these moons.  This theory holds that the planet and both moons were all formed at the same time, from the same primordial accretion disc that gave birth to all the other planets.  In other words, they may be first generation objects (formed in the birth of the solar system) rather than second generation (formed later from smaller fragments coming together).

So far, it’s all a big mystery, but we are fast closing in on the answer.   The information gained from this series of flybys has already taught us a few things about Phobos, and further analysis of it will reveal more.  Radiometric data from these flybys are being studied right now, and should be precise enough to tell us where the gaps are within the moon.  As said earlier, the gravity analysis from Mars Express will be used to help ROSCOSMOS select the spot to set down its lander in 2012, and the samples from that encounter will answer more questions.  In time, we will pry all of the secrets out of Phobos.

One final note about the possible future of Phobos: it may be a ready-made home for settlers.  What you’ve got is a big rock with a lot of holes in it, and some of those holes can probably be smoothed out and modified to make living spaces.  Since it now appears that at least a quarter of Phobos’ area is empty, that amounts to a lot of space.  If we should ever want a convenient space station orbiting Mars (and we will, eventually) Phobos might be it.  Using a body that’s already there would be a lot easier and cheaper than building something from scratch.  In some far-future time, this little rock might be riddled with underground colonies.

As you can see, the work is just starting on Phobos- and we haven’t even looked at Deimos yet.  The data from the recent encounters will be studied for years to come, and new findings will undoubtedly come to light.  Stick with us; we’ll keep you posted.

This is the story of two such missions, so closely linked that they might be viewed as two parts of the same whole. They are the 2001 Mars Odyssey satellite and the Phoenix lander. As we will see, these two projects were designed to work together, with Odyssey paving the way for Phoenix, then serving as its communication relay. They worked together toward a single goal: proving that there are large deposits of frozen water beneath the Martian surface. In this, they were successful.

This article is the first of two parts. In this one, we will look at the 2001 Mars Odyssey satellite and the science it accomplished. In our next article, we will look at the Phoenix lander. As we will see, their combined effect is a new and better understanding of Mars and its water processes.

The 2001 Mars Odyssey was launched on April 7, 2001 from Cape Canaveral, Florida. It was an ungainly assembly of rods, panels, antennae and other devices, but in general terms, it measured 2.2 meters long, 1.7 meters tall and 2.6 meters wide. At launch, it weighed 725 kilograms, which included the 331.8-kilogram spacecraft, 348.7 kilograms of fuel and 44.5 kilograms of instruments. In an effort to keep the weight down, the satellite’s designers built its framework mostly from aluminum and titanium.

Mars Odyssey carried three instruments:

1. Thermal Emission Imaging System (THEMIS)- would acquire high spatial and spectral resolution images of the surface mineralogy, and provide information on the morphology of the Martian surface. Different elements radiate thermal energy in identifiable patterns, so by studying the thermal emission of the Martian surface, it’s possible to determine which elements are present. A thermal survey would also be able to locate areas of volcanic activity, as well as geothermal zones similar to Yellowstone Park on Earth.

2. Gamma Ray Spectrometer (GRS)- would also contribute to a map of the elemental composition of the surface, and determine the abundance of hydrogen in the shallow subsurface. Hydrogen is used as an indicator of the presence of water.

3. Mars Radiation Environment Experiment (MARIE)- would characterize the Martian near-space radiation environment as related to radiation-induced risk to human explorers.

The two-part plan, mentioned earlier, was present from the beginning. Odyssey was intended to locate areas where frozen water might be present in preparation for a lander which would go down and actually take samples. By mapping the surface morphology and mineralogy, rough areas would hopefully be eliminated from the list of possible landing sites. Once the lander was on the ground, Odyssey would act as its relay to send data back to Earth.

In addition to the presence of hydrogen as an indicator of water, it was expected that the thermal survey would find other signs such as sedimentary deposits of water-soluble minerals in areas where underground ice could have melted and come to the surface at some time in the past. This would provide a long-term history of water activity on the Martian surface.

It is now generally accepted that Mars had large amounts of surface water in its distant history; many of the planet’s land-forms were obviously shaped by flowing water. However, recently there has been a growing body of evidence for the presence of deposits of frozen water on Mars now, not just in the past. For instance, data gathered by the European Space Agency’s Mars Express probe, as discussed in our article from a few weeks ago, strongly indicates that there are large amounts of water frozen just under the surface in some parts of Mars.

Once Mars Odyssey had found some interesting areas, a landing site would be chosen for the lander. This was another job where THEMIS would be useful. Big chunks of rock tend to absorb more heat than the surrounding soil, and retain it longer. Because of this, rocky places would be hotter, and would clearly show up in the thermal survey. Rocky areas tend to be rougher than sandy areas, which would make them too dangerous to be considered as landing sites.

The science to be done by this mission could be summed up as four main goals:

1. Determine whether life ever arose on Mars. Odyssey did not carry instruments to directly detect life, but data gathered by this mission would help to determine whether the Martian environment could have ever supported life. For the first time on Mars, a probe was equipped to map the presence of near-surface water and mineral deposits from past water activity.

2. Characterize the climate of Mars. Odyssey would try to understand the evolution of the Martian climate, and how water activity has effected that evolution.

3. Characterize the geology of Mars. Odyssey would determine the chemical elements that make up the Martian surface, and help explain how the planet’s land-forms developed over time. That information should provide clues to the geological and climatic history of Mars and the likelihood of finding past or present life.

4. Prepare for human exploration. Part of the Odyssey mission, as we mentioned earlier, was the Mars Radiation Environment Experiment. This would determine the levels of harmful radiation on the Martian surface, with the thought of preparing future explorers for the hazards they would face.

The Odyssey mission was a huge success, achieving all of these goals and more. Odyssey entered Mars orbit on October 24, 2001. Over the next 76 days, it performed orbital modifications which finally placed it in a two-hour science orbit. Results started coming in almost immediately. Some of the early data from Odyssey’s THEMIS device showed the presence of chloride mineral deposits in the southern Martian highlands. These are salt beds similar to the ones seen in some areas on Earth, and their presence on Mars means the same thing it means here: there was once a lot of water here. In all, THEMIS found about 200 areas with chloride mineral deposits.

The hydrogen mapping part of the mission was also successful, locating areas with elevated hydrogen levels which indicated a high probability of frozen water just underground.

While the early images of the Martian surface were taken from directly above, with Odyssey looking straight downward, later images were obtained by changing the satellite’s orbit and taking pictures of surface features from an oblique angle. By viewing a spot from directly above, and then shifting the orbit and viewing the same spot from an angle, it was possible to construct three-dimensional images of land-forms.

Here’s another important point: these images not only allow the study of the land-forms of Mars, but also of the atmosphere above them. When the light passes through the air, it is modified by the gas molecules and whatever dust and other particles are in the air. Different sizes and types of particles absorb or reflect light in different ways, so if you subtract the information about the actual ground itself, you are left with a picture of the modifications caused by air molecules and suspended particles. This can tell us a great deal about air currents and the movement of dust etc. in the atmosphere of Mars- factors which can have a huge influence on the climate, and which are necessary for a full understanding of the dynamics of the Martian atmosphere.

As we saw earlier, some of this activity had a specific purpose: locating a landing site for a future lander. A suitable site was found, and in time, the Phoenix lander was launched from Earth. This would provide the final, conclusive piece of evidence: an actual sample of ice taken from the Martian soil. Eventually Phoenix arrived and landed in the place selected for it. During its mission, Mars Odyssey provided the communications link which transmitted the data back to Earth.

But that’s another story, as they say. To find out about Phoenix, you’ll have to read our next article.

Odyssey was also the communication relay for the two famous Mars rovers, Spirit and Opportunity, whose ramblings have provided us with such spectacular pictures and data on the Martian surface.

The Odyssey satellite is still working fine, and will undoubtedly perform other jobs relating to future missions. It is the Energizer Bunny of space probes, still going and going even though its official mission is now over. Hang in there, Odyssey!

In our next article, we will take a closer look at the Phoenix lander and the science it has given us. Don’t miss it!

Sources:
Mars Odyssey: Mission Spacecraft at website of the Jet Propulsion Laboratory, California Institute of Technology: mars.jpl.nasa.gov/odyssey/mission/science/
Mars Odyssey: Mission Science at website of the Jet Propulsion Laboratory, California Institute of Technology: mars.jpl.nasa.gov/odyssey/mission/science/

Mars Odyssey: Mission Overview at website of the Jet Propulsion laboratory, California Institute of Technology: mars.jpl.nasa.gov/odyssey/mission/overview/

Mars Odyssey THEMIS: “New Orbit Gives THEMIS Better Looks at Mars Minerals” at website of Arizona State University: themis.asu.edu/news/new-orbit-gives-themis-better-looks-mars-minerals

Mars Odyssey THEMIS: “Sideways Look From THEMIS Probes Mars’ Atmosphere” at website of Arizona State University: themis.asu.edu/sideways

Mars Odyssey THEMIS: THEMIS Helps Phoenix Land Safely on Mars” at website of Arizona State University: themis.asu.edu/news/themis-helps-phoenix-land-safely-mars

Mars Odyssey THEMIS: Mars Salt Deposit Discovery Points to a New Place to Hunt for Life’s Ancient Traces” at website of Arizona State University: themis.asu.edu/news/mars-salt-deposit-discovery-points-new-place-hunt-lifes-ancient-traces

India’s space program is not exactly new. For some years now, the ISRO has been launching some outstanding Earth-orbiting satellites, some for astronomy and some for observing the Earth itself. In all of our discussions about the exploration of other bodies in the solar system and beyond, we should never forget the importance of understanding our own world. Study of the mysterious third planet is of vital importance -literally- and those who contribute to it certainly deserve our respect. (More on this in future articles.)

This time, however, we will take a look at India’s Chandrayaan-1 probe, which is in orbit around our own moon, and has helped to provide some amazing information about the presence of water there. The implications of this are obvious: without a local source of water, there will never be a permanent human presence on the moon. The cost of transporting a steady supply of water from Earth to the moon for a long period of time would be astronomical (pun intended) and would make even a small colony prohibitively expensive. But if there’s already water there, it’s a whole new ball game. Suddenly we’re talking about the possibility of permanent colonies, which might eventually become independent political entities. With water, the moon can become a world in itself.

Chandrayaan-1 was launched on October 22, 2008 from Satish Dhawan Space Center, in Sriharikota, Andhra Pradesh. It was carried into Earth orbit onboard India’s Polar Satellite Launch Vehicle, and first entered a highly elliptical orbit in which the perigee (nearest point to Earth) was about 255 km. and the apogee (farthest point from Earth) was about 22,860 km. Using its Liquid Apogee Motor (LAM), the probe performed a series of course adjustments, moving into higher and higher orbits, and finally entering a 100-km. orbit around the moon.

The satellite was roughly cuboid in shape, about 1.5 meters on a side. It weighed 1380 kg. at launch and 675 kg. at lunar orbit. (Weight decrease due to fuel expenditure.) Electrical power for all phases of the mission was provided by a single solar panel with a peak output of 750W. This solar array was stowed on the south deck of the spacecraft during the launch phase, and deployed after exit from the atmosphere. During eclipse, the satellite was powered by lithium ion batteries. For orbital maneuvers, it carried a bipropellant integrated propulsion system with enough fuel for a two-year mission, with adequate margin.

It was designed to do high-resolution remote sensing of the moon in visible, near-infrared (NIR) low energy x-rays and high-energy x-ray regions. (with high spatial and altitude resolution of 5-10 m.) of both the near and the far side of the moon.

Chandrayaan-1 also carried a lander, the Moon Impact Probe (MIP), which was deployed when lunar orbit was achieved. The MIP hard landed on the lunar surface and conducted various explorations. In a moment of symbolic significance, the Indian tricolor was planted on the moon: one of Earth’s oldest cultures moving forward into the future.

In a true spirit of international cooperation, Chandrayaan-1 carried 11 scientific instruments contributed by India, the U.S., the U.K., Germany, Sweden and Bulgaria.

The actual mission has now been completed, and Chandrayaan-1 has moved to a 200-km. retirement orbit around the moon- but the fun is just beginning, because the data sent back by the probe and its lander will be analyzed for years to come.

As we said earlier, some of this information has now given strong indication of water on the moon. A few months ago, radar data from Chandrayaan-1 and also from two NASA spacecraft, the Deep Impact probe and the Lunar Reconnaissance Orbiter, indicated that there is a thin layer of water, only a few molecules thick, on the lunar surface. Scientists are theorizing that these meager traces of water may be evaporating and re-condensing in a “hop-scotching” pattern that causes them to move toward the lunar poles, becoming more concentrated as they go. There are craters at the poles that are permanently shaded, and have not felt sunlight for eons. Here, it is thought, the water may be concentrating and freezing.

You are probably shaking your head with disbelief as you read these words. We have been taught for so long that the moon is a dry, inactive world, that we now find it hard to believe that there is an ongoing process of water movement there. Granted, these water molecules are so few and scattered that you wouldn’t even be aware of them if you standing on the lunar surface, but if this process is happening all over the lunar surface, and if the water really is collecting in those polar craters, the amounts could be very significant, indeed.

But where is this water coming from? Is it seeping up from underground deposits? No, while underground deposits of water may also exist on the moon, the layer of molecules that we’re talking about now is apparently being made in an ongoing natural process. Carl Pieters of Brown University has suggested that it may be caused by the solar wind, which is constantly slamming hydrogen ions into the oxygen-rich rocks.

Think of the implications; water is actually being made on the moon. That means there will always be more of it. It’s not like a mineral, which exists in a finite amount and can eventually be exhausted. It’s a renewable resource.

The evidence for lunar water continues to mount. A news release at the NASA website dated March 1, 2010, says that analysis of data from a radar device which was designed by NASA and carried aboard Chandrayaan-1 has revealed more than 40 permanently-shaded craters near the lunar north pole which exhibit reflective qualities consistent with water ice. While the amount of water depends on how thick it is, scientists are estimating that there could be at least 1.3 trillion pounds of water in those craters.

The release quotes Paul Spudis, principal investigator of the Mini-SAR experiment at the Lunar and Planetary Institute in Houston: “The emerging picture from the multiple measurements and resulting data of the instruments on lunar missions indicates that water creation, migration, deposition and retention are occurring on the moon. The new discoveries show the moon is an even more interesting and attractive scientific, exploration and operational destination than people had previously thought.”

This is exciting stuff, and there is much more to be learned. India is moving onto the stage of planetary exploration, and will do much more in the years to come. Chandrayaan-1 is just the beginning- but a very good one. Thanks to the groundwork that was laid by Chandrayaans and the other lunar probes, it now appears certain that in time, permanent settlements, possibly of considerable size, will exist on the moon.

In connection with this, there is a small but significant political note that should be made. Only last week, President Obama announced that putting humans on the moon in the near future should no longer be a priority for our nation. He is absolutely right. Exploration and settlement should be our long-term goal, but not our short-term goal. In the short-term, there is much more to be learned from unmanned space probes, on the moon and various other locations in the solar system, and a human moon expedition would be a waste of money that could be spent doing more valuable research. We will go back to the moon, and eventually our descendants will live there, but before we get to that point, there is much to be learned from great unmanned projects such as Chandrayaan-1.

Sources:
“NASA Radar Finds Ice Deposits at Moon’s North Pole; Additional Evidence of Water activity on Moon” at NASA website: nasa.gov/home/hqnews/2010/mar/HQ_10-055_moon_ice.html

“Chandrayaan-1, India’s First Scientific Mission to the Moon” (mission webpage) at website of Indian Space Research Organization: isro.org/Chandrayaan/htmls/home.htm

“Chandrayaan-1, India’s First Scientific Mission to the Moon- Mission Sequence” at website of the Indian Space Research Organization: isro.org/Chandrayaan/htmls/mission_sequence.htm

Partain, Gary: “The Moon May Be Wetter Than We Thought” at Associated Content: associatedcontent.com/article/2232581/unexpected_water_on_the_moon_results_pg3.html?cat=15