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.

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)

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

The Mars Polar Lander mission was launched in early 1999 and following an 11 month cruise the spacecraft arrived at Mars in December 1999. The mission had been designed to study the weather, climate, water and carbon dioxide concentrations on Mars and a number of scientific instruments had been incorporated into the Polar Lander to undertake studies when it arrived. However the last contact with the craft came just prior to atmospheric entry and no further contact has ever been established. The exact cause of the communication loss is not known although an investigation identified the most likely cause as being a software error that misread vibrations caused by deployment of the crafts legs as touchdown on the surface. This would have caused the descent engines to switch off while the craft was still above the surface of the planet resulting in an extremely hard landing. In late1999 and early 2000 images from the Mars Global Surveyor were used to search for the Polar Lander although this was unsuccessful and contact with the craft was never established.

The search for the Mars Polar Lander has not been given up entirely however and in the last two years images from the HiRISE camera on the Mars Reconnaissance Orbiter have been used to try and identify the site of the craft. This began in 2008 when 18 images were released to the public with a request that anyone who wanted to assist the search could view the images and contact the HiRISE team with any points of interest. This was not successful although as new images have been released the search has continued. Some of the existing images have been improved by the HiRISE team and these were released in December 2009. Whether these will finally reveal the site of the Mars Polar Lander remains to be seen but the search will continue in 2010.

The Mars Phoenix Lander was the first mission to Mars following the failure of the Mars Polar Lander. The aim of the mission was to study the history of water on the planet and to search for environments suitable for life to have existed. The craft was launched in August 2007 and arrived at the planet in May 2008. It successfully negotiated the descent to the planet and over the next few months carried out its mission and transmitted the data back to Earth. However the craft was not designed to cope with the Martian winter and as this closed in contact was lost.
During winter the Phoenix Lander should have gone into safe mode and if it survived the harsh conditions it should try to recharge its batteries as the weather improves. On January 18 the Mars Odyssey Orbiter will begin a mission to start listening for any signs of life from the Phoenix Lander. Odyssey will pass over the location of the craft 10 times a day over a 3 day period in January and will follow this up with two longer search periods in February and March. During the two longer periods it will passively listen as well as transmitting signals which the Phoenix Lander will potentially be able to hear.

If the Phoenix Lander has survived the Martian winter it should start to periodically attempt to communicate once the solar panels have generated enough electricity. If it does this then Odyssey should be able to hear these and would try to re-establish contact. The initial task would then be to try and determine the condition of the Phoenix Lander and the capabilities it retains. This information could then be used to determine whether the craft has any remaining useful life.

Only time will tell whether the attempts to locate and communicate with both the Mars Polar Lander and the Mars Phoenix Lander are successful. It would be a tremendous achievement to re-establish contact and use one or both of the craft for further studies of Mars. This may be an unlikely scenario although it is not impossible and the next few months will be an interesting time in the study of Mars.