Mars 2 ... continuing the discovery of information on the Red Planet.


The sunset image is from the Pathfinder Mission, and demonstrates that romantic evenings can be possible on Mars, but kissing through helmets might dampen the mood.

Mars has permanent ice caps at both poles composed mostly of solid carbon dioxide ("dry ice"). The ice caps exhibit a layered structure with alternating layers of ice with varying concentrations of dark dust. In the northern summer the carbon dioxide completely sublimes, leaving a residual layer of water ice. It's not known if a similar layer of water ice exists below the southern cap (left) since its carbon dioxide layer never completely disappears. The mechanism responsible for the layering is unknown but may be due to climatic changes related to long-term changes in the inclination of Mars' equator to the plane of its orbit. There may also be water ice hidden below the surface at lower latitudes. The seasonal changes in the extent of the polar caps changes the global atmospheric pressure by about 25% (as measured at the Viking lander sites). The image to your left is of the North Polar Cap in mid-Martian summer. The diameter of this cap is about 1100 km, and most of what you see is frozen water.

Recent observations with the Hubble Space Telescope have revealed that the conditions during the Viking missions may not have been typical. Mars' atmosphere now seems to be both colder and dryer than measured by the Viking landers. ( more details from STScI)


The Viking landers performed experiments to determine the existence of life on Mars. The results were somewhat ambiguous but most scientists now believe that they show no evidence for life on Mars (there is still some controversy, however). Optimists point out that only two tiny samples were measured and not from the most favorable locations. More experiments will be done by future missions to Mars.



More recently, the Mars Sojourner and Pathfinder missions successfully landed on the surface. A small robotic car moved around, taking pictures and making close analysis of rock types. A few images from that mission are included below, and if you want to see more surface photos, click on the Pathfinder website.








A small number of meteorites (the SNC meteorites) are believed to have originated on Mars.

On 1996 Aug 6, David McKay et al announced the first identification of organic compounds in a Martian meteorite. The authors further suggest that these compounds, in conjunction with a number of other mineralogical features observed in the rock, may be evidence of ancient Martian microorganisms. I was out in the San Francisco area when this Mars meteor story broke from the Ames Research Center. It was incredibly exciting to be so close to the action. Exciting as this is, it is important to note while this evidence is strong it by no means establishes the fact of extraterrestrial life. There have also been several contradictory studies published since the McKay paper. Remember, "extraordinary claims require extraordinary evidence." Much work remains to be done before we can be confident of this most extraordinary claim. Whether anyone ever really proves the geological formations in the rock to be bacterial fossils or not is not as important as the effect this story had on the public in general and the politicians in particular. When NASA asked for money to fund extra Mars missions, the Federal Government was more than willing to cough up some large dollar figures because of the potential of finding evidence of life, if not even life itself underneath the surface dust. Keep in mind that the lack of an appreciable atmosphere means no gases to block harmful solar radiation. Any life forms living on the surface would suffer extreme radiation and mutate to death. Indeed, the movie "Total Recall" shows mutant humans who suffered their horrible fate when the original Mars settlers constructed domes of cheap, non-UV protective glass.

Large, but not global, weak magnetic fields exist in various regions of Mars. This unexpected finding was made by Mars Global Surveyor (seen in an artist's rendition to your left, photographing Olympus Mons) just days after it entered Mars orbit. They are probably remnants of an earlier global field that has since disappeared. This may have important implications for the structure of Mars' interior and for the past history of its atmosphere and hence for the possibility of ancient life.

Also orbiting Mars presently is the Mars Odyssey satellite. This satellite is bouncing laser beams off the surface to generate fantastic topographic maps of Mars.

These current satellite missions are accomplishing wonders, and a trove of new scientific data is accumulating which will give engineers, geologists, and terraformers plenty of work to keep them busy for many years to come. To see the current progress, check out the JPL Mars Site.

When it is in the nighttime sky, Mars is easily visible with the unaided eye. Its apparent brightness varies greatly according to its relative position to the Earth. There are several Web sites that show the current position of Mars (and the other planets) in the sky. More detailed and customized charts can be created with a planetarium program such as Starry Night.

Mars' Satellites, Phobos and Deimos

Mars has two tiny satellites which orbit very close to the surface:







Meaning of name


9,000 km

11 km

1.08x10e16 kg





23,000 km

6 km

1.80x10e15 kg




To learn more about these two little moons, go to Martian Moons. ("Distance" is measured from the center of Mars).

During the 1999 Nobel Conference at Gustavus College, I had the opportunity to listen to and then meet Dr. Roald Sagdeev. He was a former head of the Soviet Space Research Department and a project director for several Soviet satellite missions. After listening to his speech, purchasing and reading his book, I found a few interesting things about their program, as well as the US program. The Soviets and Americans had reached a gentleman's agreement. America would send spacecraft to Mars and share information, while the Soviets would send spacecraft to Venus and share information. Over the ensuing 10-15 years, the two bitter Cold War enemies shared science information despite their military disagreements. Apparently, the Soviets and Americans were working on star wars technology, which meant laser weapons capable of destroying space satellites, either from space or from the ground. Since the Star Wars Treaty was signed by America and the Soviet Union, it was impossible to test the technology without the other side knowing it. But the Russians had a pretty interesting plan. They were going to send a space probe to Mars' moon Phobos and then blast material off the surface, catch it in a web, and return samples to Earth for analysis. An excellent instrument to do this blasting would be a powerful laser. Fortunately, for the Americans, they had spies in the Soviet program so they knew this laser test was not a space mission but a military test. The Americans therefore made a proposal to the Soviets. If the Soviets were willing, would they mind if a wonderful new camera America was testing could be attached to the Soviet craft. Caught "red-handed" the Soviets had to agree. Now the Americans could aim their camera, not at the surface of Phobos, but at the Soviet star wars laser weapon. Unfortunately, both Phobos 1 (seen in an artist's rendition to your left) and its back-up Phobos 2 were lost, and both "tests" failed.

Mars is the JPL website that will offer more information than I can place in this course, as well as some nice connecting links.

Mars Fossils? This is the rock that caused all of the excitement in 1996. Known more simply as ALH84001.0, this rock held tiny geological formations that looked remarkably like bacterial fossils.





For more on the story, click on the website.

Mars Global Surveyor

Mars Pathfinder


The images above can be found at the Mars Society, a group of private citizens dedicated to the exploration, terraforming, and colonization of the Red Planet.

Well, there it is, Cydonia ... the supposed site of an alien city on Mars. Martian Pyramids is a website that is devoted to the meaning of these strange features on the surface, imaged by the Viking missions in the 1970's. For years, the "face on Mars" has fascinated the public, as too has the pyramids. In fact, these very pyramid structures, seen in the lower left of the left image above, inspired the movie "Total Recall."

Mars by Percival Lowell

No single person has more connection to Mars than Percival Lowell. His story is one of the most interesting accounts in the history of Astronomy. Excited by the visions of canals reported by Giovanni Schiparelli, Lowell founded an observatory at Flagstaff, Arizona and dedicated himself to the study of Mars. The more Lowell studied Mars, the more he saw there. Soon he was seeing a vast system of canals, literal straight-line channels running all over the surface, connecting the polar caps to cities and junctions. Their purpose, according to Lowell was to help a race of Martians survive a dying world. Lowell's book can be read by clicking on the web site.

The visions and writing of Lowell inspired an entire industry. HG Wells was inspired to write a book, The War of the Worlds which depicted the Martians coming to the Earth where there was a plentious supply of water. Orson Wells narrated the story in 1938 on a public radio broadcast. Americans from coast to coast were frightened by the reading, many hid in the homes, and others committed suicide. To read his entire book, click on the War of the Worlds by HG Wells for the complete text.

After HG Wells, Edgar Rice Burroughs wrote a series of Mars-related books. The collection of books by Edgar Rice Burroughs is on line, with complete texts. Princess of Mars, Gods of Mars, Warlord of Mars, and Thuvia, Maid of Mars.

Two movies, of the many that have tickled our fancy with Mars stories can be looked upon briefly at Mission to Mars and Mars Attacks.

A really fascinating site, if you have ever watched the movie "Aliens" (the second in the "series"), deals with the subject of terraforming a planet. The idea in the movie was to construct a huge machine that would manufacture air and make an entire planet liveable. The movie called it a "shake and bake colony." While Mars cannot hold an atmosphere due to its lack of sufficient mass, some have proposed digging a deep hole, closer to the interior to that gravity will then be able to hold on to the oxygen that might be put there. Other ideas include burrowing into the sides of the Valles Marineris, like in the movie "Total Recall."


To see some interesting proposals on the subject, click on Terraforming Mars.


Perhaps the most interesting site I have found to date that deals with lore and truth about Mars is the Chronology of Mars website. This places has connections to information about Mars going back to the beginning of history, a connection to every mission to Mars whether it was successful or a failure, and a connection to fun stuff about the planet. You can see a condensed version of the Chronology of Mars that I copied into the course strictly for educational purposes only.


Now, it is time to do something really cool. The Mars Global Surveyor is returning images of the Red Planet's surface, and planetary geologists are trying to cataloge the craters. Since the task is beyond the ability of grad students and their professors, a website has been opened that allows any student of Astronomy an opportunity to do meaningful work related to these Martian craters. Please go now to the Mars Crater Page and check out your lab assignment connected with this course.

To learn more about planet Mars, go to the JPL webpage and click on Mars.

Here are 10 questions I would like you to answer about the planet Mars.

1) Give a brief description of the planet's surface appearance.

2) What gives Mars its red color?

3) What is so special about Olympic Mons?

4) Why might the Mars Society be interested in the Valles Marineris?

5) What are the names of the 2 moons of Mars?

6) Why would water boil on Mars?

7) Why would glass domes be necessary in a surface city to protect the pioneers that would want to live on Mars?

8) What spacecraft first landed on Mars and when did this event take place?

9) What is the current scientific interest in the Martian soils and rocks that might tell us about the geologic history of Mars?

10) What are the polar caps composed of and what happens to them in summer?

There is so much to Mars, in fact more than an entire course could possibly hold, and as time goes by, perhaps more of the interesting Mars stories, fictional and true, can be included in this course. Before you go any further, how about checking to see if you are certain about your answers to the short quiz above, and then sending your response my way at the Mars Quiz page.

For now though, it is time to move on. Please go to the Introduction to the Gas Giants page.

If you want, you can go back to Mars 1, or one of the Inner Planets (Mercury, Venus, Earth), or return to Introduction to the Inner Rocky Worlds, or the Planet Introduction, or the Syllabus.


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