1. Module 12: Mars - the Red Planet Activity 1: Destination Mars

2. Summary: In this Activity, we will investigate (a) Mars’ vital statistics, and (b) Missions to Mars

3. (a) Mars’ Vital Statistics Now we’ll look at the bulk properties of our other planetary neighbour, Mars, and compare them to those of Earth and Venus. Again, structurally all three have much in common:

4. Mars 0.53 D  M = 0.11 M  EarthVenus 0.96 D  M = 0.81 M  DD M = M  crust core mantle

5. As Mars has two natural satellites, Phobos and Diemos (see later), the mass of Mars can be calculated by observing their orbits and using Kepler’s Third Law. As well as being much smaller than Earth (only 53% of Earth’s diameter), Mars turns out to have a much lower density than does Earth - so its interior must be significantly different. In particular, its core must be smaller and probably less dense too.

6. EarthVenusMars Av. Distance from Sun 1 AU1.52 AU0.72 AU Mars is half as far again from the Sun as is Earth, which means that it receives less than half as much sunlight (i.e. half as many photons per unit area per unit time). We will see that the distances between the planets quickly increase as we move out from the Sun.

7. EarthVenusMars Av. Distance from Sun 1 AU1.52 AU0.72 AU Length of “Year” 1 y  0.62 y  1.88 y  A year on Mars takes almost twice as long as a year on Earth.

8. EarthVenusMars Av. Distance from Sun 1 AU1.52 AU0.72 AU Length of “Year” 1 y  0.62 y  1.88 y  Length of solar day 117 d  retrograde 1 d  1.03 d  Surprisingly, a day on Mars is almost the same length as one on Earth. Like the Earth, the difference between a solar day (time between successive “noons”) and sidereal day (rotation period with respect to background stars) is only a few minutes.

9. EarthVenusMars Av. Distance from Sun 1 AU1.52 AU0.72 AU Length of “Year” 1 y  0.62 y  1.88 y  Length of solar day 117 d  retrograde 1 d  1.03 d  Inclination of axis 177°23.5°25° Another convenient coincidence? Almost identical axis tilts give the Earth and Mars similar seasonal patterns - except that seasons on Mars last almost twice as long.

10. EarthVenusMars Av. Distance from Sun 1 AU1.52 AU0.72 AU Length of “Year” 1 y  0.62 y  1.88 y  Length of solar day 117 d  retrograde 1 d  1.03 d  Inclination of axis 177°23.5°25° Acceleration due to gravity 1 g  0.38g  0.90g 

11. Objects weigh only about 40% of their terrestrial weight when on Mars. Settlers on Mars would need to make adjustments to cope with the ‘reduced gravity’.

12. The main reasons why we are not likely to plan settlements on Venus involved the atmosphere and surface temperature. Let’s look at the bulk properties of the atmosphere and surface temperature on Mars:

13. EarthVenusMars av. albedo0.390.160.76 (cloud tops) The rusty orange-red, cloudless surface of Mars is much less reflective than cloud-covered Venus or even Earth.

14. EarthVenusMars av. albedo0.390.160.76 (cloud tops) atmosphere96% CO 2 3.5% N 2 0.2% H 2 O & acids 78% N 2 20% O 2 0.03% CO 2 ~2% H 2 O 95% CO 2 2.3% N 2 trace O 2 & H 2 O Like Venus (and the primeval Earth), Mars has an atmosphere composed mostly of carbon dioxide.

15. EarthVenusMars av. albedo0.390.160.76 (cloud tops) atmosphere96% CO 2 3.5% N 2 0.2% H 2 O & acids 78% N 2 20% O 2 0.03% CO 2 ~2% H 2 O 95% CO 2 2.3% N 2 trace O 2 & H 2 O av. surface pressure 90 p atm 1 p atm 0.01 p atm Unlike Venus, the atmosphere that Mars has managed to retain is very thin indeed, as you would expect given the low acceleration due to gravity.

16. Atmospheric pressures on Earth only become as low as 0.01 p atm at an altitude of 40km.

17. EarthVenusMars av. albedo0.390.160.76 (cloud tops) atmosphere96% CO 2 3.5% N 2 0.2% H 2 O & acids 78% N 2 21% O 2 0.03% CO 2 ~2% H 2 O 95% CO 2 2.3% N 2 trace O 2 & H 2 O surface temperature 472°C- 50°C  + 50°C - 140°C  + 20°C av. surface pressure 90 p atm 1 p atm 0.01 p atm

18. Average temperatures on Mars are cooler than on Earth, as you would expect for a planet 50% further from the Sun. With almost no appreciable atmosphere to insulate it, temperature changes on Mars can be quite severe - up to 100°K between night and day at the equator in summer.

19. (b) Missions to Mars Although Mars is not our closest planetary neighbour, it is the most accessible one. Its history appears to be similar enough to that of Earth to make the study of Mars important for our understanding of our own planet too. In the long term, Mars is the most likely site if humans ever attempt to colonize and “terraform” a planet other than our own.

20. There have been several space missions to Mars, with mixed results. Although Mars does not have the formidable atmospheric conditions of Venus, its distance from Earth plus its distance from the Sun (and relatively low supply of solar energy) create problems for mission planners. As we will see, several of the past Mars missions were spectacularly unsuccessful. Since then, NASA has been rethinking its recent ‘low cost’ missions approach, despite its early spectacular success with the Mars Pathfinder Mission. Here we’ll give a very brief summary of each of the recent missions.

21. Mariner 9 The Mariner Mars 7 mission originally consisted of two spacecrafts on complementary missions, but Mariner 8 failed to launch properly. Mariner 9 then combined the mission objectives of both. The spacecraft was turned off in October 1972. The Mariner 9 mission resulted in a global mapping of the surface of Mars, including the first detailed views of the volcanoes, Valles Marineris, the polar caps, global dust storms and the satellites Phobos and Deimos.

22. NASA’s Viking Mission was composed of Viking 1 and Viking 2, each consisting of an orbiter and a lander. The primary mission objectives were to obtain high resolution images of the Martian surface, characterize the structure and composition of the atmosphere and surface, and search for evidence of life. Viking Mission to Mars

23. Viking 1 was launched in August 1975 and arrived at Mars in June 1976. One month later the Viking 1 Lander separated from the Orbiter and touched down at Chryse Planitia. Viking 2 was launched in September 1975 and entered Mars orbit in August 1976. The Viking 2 Lander touched down at Utopia Planitia a month later. The Orbiters imaged the entire surface of Mars at a resolution of 150 to 300 metres, and selected areas at 8 metres. NASA powered down the Viking 2 Orbiter in 1978 and the Viking 1 Orbiter in 1980. The Viking 1 orbiter

24. The Viking Landers sent back images of the surface, took surface samples and analyzed them to determine their composition and look for signs of life, studied the composition of the atmosphere and Martian meteorology, and deployed seismometers. The Viking 1 lander The Viking 2 Lander stopped sending signals to Earth in April 1980, and the Viking 1 Lander stopped in November 1982, after transmitting over 1400 images of the two sites.

25. The Phobos Project The USSR launched two missions to Phobos, one of the natural satellites of Mars, in July 1988. The mission plan intended the two spacecraft, Phobos 1 and Phobos 2, to be placed into Mars orbit so that they would be in an almost fixed position 50 m above the surface of Phobos - and aim laser and ion beams at Phobos in order to determine its chemical makeup.

26. Phobos 1 failed 2 September 1988 due to a software error. Phobos 2 operated normally, gathering data on the Sun, interplanetary medium, Mars, and Phobos. Shortly before the final phase of the mission, during which the spacecraft was to approach within 50 m of Phobos’ surface and release two landers (a mobile “hopper” and a stationary platform), contact with Phobos 2 was lost due to a malfunction of the on-board computer. The mission officially ended 27 March 1989.

27. To quote NASA, “Contact with Mars Observer was lost in August 1993, three days before scheduled orbit insertion, for unknown reasons and has not been re-established. It is not known whether the spacecraft was able to follow its automatic programming and go into Mars orbit or if it flew by Mars and is now in a heliocentric orbit. Although none of the primary objectives of the mission were achieved, cruise mode data were collected up to loss of contact”. Launched in September 1992, Mars Observer, the first of the planned Observer series of planetary missions, was designed to study the geoscience and climate of Mars. The Mars Observer

28. The final report of the board stated that: “After conducting extensive analyses, the board reported that the most probable cause of the loss of communications with the spacecraft was a rupture of the fuel (monomethyl hydrazine (MMH)) pressurization side of the spacecraft's propulsion system, resulting in a pressurized leak of both helium gas and liquid MMH under the spacecraft's thermal blanket. The gas and liquid would most likely have leaked out from under the blanket in an unsymmetrical manner, resulting in a net spin rate. This high spin rate would cause the spacecraft to enter into the "contingency mode," which interrupted the stored command sequence and thus, did not turn the transmitter on.” An independent board, headed by Timothy Coffey (research director of Naval Research Laboratory, Washington, D.C ) was set up to report on the failure of the Mars Observer. For the full report, see: http://www.msss.com/mars/observer/project/mo_loss/nasa_mo_loss.txt

29. Mars Pathfinder The Mars Pathfinder, the second of NASA’s low-cost planetary Discovery missions, landed successfully on Mars in July 1997. The mission consisted of a stationary lander and a surface rover, with the primary objective of demonstrating the feasibility of low-cost landings on and exploration of the Martian surface.

30. Pathfinder directly entered the planet’s atmosphere and landed by bouncing on inflated airbags. The lander operated nearly three times its design lifetime of 30 days, while the rover operated 12 times its design lifetime of seven days. The mission officially ended in November 1997. As we will see in a later Activity, the Pathfinder provided strong evidence that its landing site underwent massive flooding by water two billion years ago. It also provided unexpected evidence which is still being analysed that the rocks at its landing site, while basaltic in nature, were rather different to what was expected on the basis of similar geology on Earth and from the study of meteorites believed to have originated on Mars.

31. Mars Global Surveyor The Mars Global Surveyor (MGS) mission is the replacement for the Mars Observer mission. To quote NASA, “The science objectives involve high resolution imaging of the surface, studies of the topography and gravity, the role of water and dust on the surface and in the atmosphere of Mars, the weather and climate of Mars, the composition of the surface and atmosphere, and the existence and evolution of the Martian magnetic field”.

32. The spacecraft began its Mars orbit insertion in September 1997. The primary mapping mission began about March, 1999. The spacecraft was placed into a “sun-synchronous” orbit so that each image can be taken with the Sun at the same mid-afternoon azimuth, for a planned period of one Martian year.

33. The picture below is a flat map generated by the Mars Orbiter Laser Altimeter (MOLA) aboard the Mars Global Surveyor. Each elevation point is known to an accuracy of at least 13 metres, with large areas of the flat northern hemisphere known to better than two metres, which is more accurate than our knowledge of the topography of many of the continental regions on Earth.

34. The Mars Global Surveyor was also designed to be used to relay data to Earth from further U.S. and international missions. Mars Global Surveyor was the first spacecraft in a decade-long exploration of Mars by NASA, with launches planned every 26 months, to take advantage of the times when Earth and Mars are closest to each other in their orbits around the Sun. Mars Global Surveyor completed its primary mission on January 31, 2001 (having studied the entire Martian surface, atmosphere, and interior) and is now in an extended mission phase. These planned missions involve sending orbiters, landers, rovers, and probes to Mars.

35. The Mars Surveyor 1998 program was made up of two spacecraft launched separately, the Mars Climate Orbiter and the Mars Polar Lander. The two missions were designed to study Martian weather and climate, and water and carbon dioxide levels. Mars Climate Orbiter and Polar Lander The Mars Climate Orbiter was launched successfully in December 1998, but contact was lost as it was about to go into orbit around Mars. Mars Climate Orbiter

36. The resulting enquiry found that the Climate Orbiter had in fact approached Mars much more directly than planned, due almost certainly to a programming error, where data originally calculated in Imperial units was mistakenly and disastrously interpreted as being in metric units! As a result, the Climate Orbiter apparently attempted to go into orbit only 57 km above the surface of Mars, instead of a planned altitude of about 140 – 150 km. Although the Martian atmosphere is very thin, the initial speed of the Orbiter would have resulted in the spacecraft being destroyed by atmospheric stresses and friction at this low altitude. The findings of the NASA Failure Review Board can be found on the Internet at http://nssdc.gsfc.nasa.gov/planetary/text/mco_pr_19991110.txt http://nssdc.gsfc.nasa.gov/planetary/text/mco_pr_19991110.txt

37. The Mars Polar Lander was a particularly interesting mission, from a scientific point of view, as the plan was to land it less than 1000 km from the Martian south pole, near the edge of the carbon dioxide ice cap in Mars’ late southern spring. The terrain appears to be composed of alternating layers of clean and dust-laden ice, and may represent a long-term record of the climate, as well as a likely source of volatile compounds such as water and carbon dioxide. Mars Polar Lander The failure of the Climate Orbiter happened while the Polar Lander was already en-route to Mars.

38. Atmospheric entry calculations were redone, in order to avoid the unit conversion problems which had caused the crash of the Climate Orbiter. However, contact was permanently lost with the Polar Lander on 3 December 1999, just prior to the time calculated for atmospheric entry. The Review Board report into the mission failure is at http://nssdc.gsfc.nasa.gov/planetary/text/nasa_pr_20000328.txt. http://nssdc.gsfc.nasa.gov/planetary/text/nasa_pr_20000328.txt The report concluded that “the most probable cause of the failure was the generation of spurious signals when the lander legs were deployed during descent. The spurious signals gave a false indication that the spacecraft had landed, resulting in a premature shutdown of the engines and the destruction of the lander when it crashed on Mars”. To find out more about the Mars Polar Lander, visit http://nssdc.gsfc.nasa.gov/nmc/tmp/1999-001A.html http://nssdc.gsfc.nasa.gov/nmc/tmp/1999-001A.html

39. There were reports in March 2001 that the US National Imagery and Mapping Agency (NIMA), a combat support agency of the US Department of Defence, had analysed high resolution imagery from the Global Surveyor and found features in several images that “could be indicative of the lander and its protective aeroshell”. It was clear from the initial NASA press releases that NASA and NIMA had rather different interpretations of the imagery, and there has been little mention of these reports since (and in fact the original NASA press release is not longer available!). For interesting commentaries on the release see: http://www.spacedaily.com/news/mars-polar99-01a.html http://www.space.com/missionlaunches/missions/mpl_new_matter_010322.html

40. Nozomi (Japanese for “hope”) was to be the first Japanese Mars orbiting mission, designed to study the martian upper atmosphere and its interaction with the solar wind and to develop technologies for use in future planetary missions. The mission was also to relay images of Mars’ surface. Nozomi Nozomi was launched in July 1998, but a series of unfortunately mishaps prevented it from ever reaching its destination. After more than 5 years in space, it became clear that Nozomi would run out of fuel before reaching Mars. In later 2003, the spacecraft was put in a heliocentric orbit to avoid any possible collision with Mars. For mission details, see http://solarsystem.nasa.gov/missions/profile.cfm?MCode=Nozomi http://solarsystem.nasa.gov/missions/profile.cfm?MCode=Nozomi

41. The 2001 Mars Odyssey orbiter mission was launched from Cape Canaveral on April 7 2001, and reached Mars on 24 October 2001 and began mapping the red planet’s surface. 2001 Mars Odyssey The main scientific objectives for this mission are the analysis of the Martian radiation environment, the mapping of surface chemical elements and minerals, and the search for water. It has been conducting this mission since January 2002 and completed its 10,000 th Mars orbit in May 2004. The primary mission continues until August 2004. It also provides communication support for other missions, including the Mars Exploration Rovers.

42. There are three instruments aboard Odyssey: THEMIS – the Thermal Emission Imaging System – is a visible and infrared camera used to study Martian geology, mapping the mineral distribution of the surface. GRS – the Gamma Ray Spectrometer – observes gamma radiation coming from the surface of Mars (due to cosmic rays) which tells of the abundance of 20 primary elements. The GRS also detects neutrons which indicate the presence of water. MARIE – the Martian Radiation Experiment – measures the high energy radiation environment of Mars coming from sources such a cosmic rays. For more details about these three instruments and how they work, see: http://mars.jpl.nasa.gov/odyssey/technology/http://mars.jpl.nasa.gov/odyssey/technology/

43. Mars Express The European Space Agency mission Mars Express was launched in June 2003 and aims to study the Martian atmosphere and surface from a polar orbit. Unfortunately after its separation from the probe and descent onto the Martian surface, contact with the lander was lost. Artist’s impression of Mars Express Arriving at its destination on December 2003, the probe delivered the Beagle 2 lander on Christmas day that was to perform exobiology and chemistry research.

44. Mars Express carries a number of instruments, one of which is the High Resolution Stereo Camera (HRSC). HRSC is designed to image the entire surface of Mars in full colour and 3D with a resolution of 10 m, and as low as 2 m in some selected areas. Other onboard instruments include: OMEGA – a visible and infrared mineralogical mapping spectrometer, is used to map the surface composition; SPICAM – an ultraviolet and infrared atmospheric spectrometer for determining the atmospheric composition; ASPERA – an energetic neutral atoms analyser, for determining how much of the Martian atmosphere is eroding by solar wind; and MARSIS – a sub-surface sounding radar altimeter to map below the Martian surface to a depth of a few kilometres. Mars Express carries a number of instruments, one of which is the High Resolution Stereo Camera (HRSC). HRSC is designed to image the entire surface of Mars in full colour and 3D with a resolution of 10 m, and as low as 2 m in some selected areas. Other onboard instruments include: OMEGA – a visible and infrared mineralogical mapping spectrometer, is used to map the surface composition; SPICAM – an ultraviolet and infrared atmospheric spectrometer for determining the atmospheric composition; ASPERA – an energetic neutral atoms analyser, for determining how much of the Martian atmosphere is eroding by solar wind; and MARSIS – a sub-surface sounding radar altimeter to map below the Martian surface to a depth of a few kilometres. Computer-generated image of a portion of the Grand Canyon of Mars, based on original Mars Express data.

45. One of the primary objectives of the Mars Express mission is to search for water in its various chemical forms (i.e. water ice, water vapour and liquid water). To find out more about Mars Express, visit http://www.esa.int/science/marsexpress http://www.esa.int/science/marsexpress The various instruments are able to search for underground liquid water, water vapour escaping from the atmosphere, and, by mapping the surface composition, search for water ice – which it has already successfully detected! (For details see the next Activity.)

46. Mars Exploration Rovers Launched in 2003, the Mars Exploration Rovers – Spirit and Opportunity – successfully landed on opposite sides of Mars in January 2004. The rovers have greater mobility then the Pathfinder rover and carry a more advanced scientific payload. With a set of sophisticated instruments the rovers’ mission focuses on determining whether there was liquid water present on Mars in the past. The rovers were designed to explore the surface of Mars for 90 days. At the time of writing, they have been active for more that twice this time.

47. Spirit’s landing site: Gusev Crater Opportunity’s landing site: Meridiani Planum Interesting features: Interesting feature: A. Columbia Hills Complex A B. Airbag bounce mark B C. Rock outcropping C

48. While there is no liquid water on the surface of Mars today, the twin rovers will look signs of past flowing water and geological features that form only in the presence of water. To find out more about Mars Exploration Rovers Mission, visit http://marsrovers.jpl.nasa.gov/http://marsrovers.jpl.nasa.gov/ The two rover landing sites were specifically chosen as potential sites of past water on Mars. The Gusev Crater, a giant impact crater, may have been a former lake, and Meridiani contains a lot of the mineral hematite which can form in various ways but usually requires water. After evaluating the composition of soil and rocks from the recorded images and spectra, scientists hope to be able to establish whether life could have been sustained on Mars in the past.

49. Follow this linkFollow this link to see a list of Internet sites containing more information about all these Mars missions!

50. Although space missions to Mars have had mixed success, some have achieved and even surpassed their initial aims. In the next Activity we will go on to look at what these space missions have told us about the atmosphere and surface of Mars.

51. NASA: Venus globe http://nssdc.gsfc.nasa.gov/image/planetary/venus/venusglobe.jpg http://nssdc.gsfc.nasa.gov/image/planetary/venus/venusglobe.jpg Earth globe http://pds.jpl.nasa.gov/planets/welcome/earth.htm http://pds.jpl.nasa.gov/planets/welcome/earth.htm Mars globe http://pds.jpl.nasa.gov/planets/welcome/thumb/marglobe.gif http://pds.jpl.nasa.gov/planets/welcome/thumb/marglobe.gif Mars - Valles Marineris http://nssdc.gsfc.nasa.gov/image/planetary/mars/marsglobe1.jpg http://nssdc.gsfc.nasa.gov/image/planetary/mars/marsglobe1.jpg Mars Polar Lander http://nssdc.gsfc.nasa.gov/thumbnail/spacecraft/mars_polar_lander.gif http://nssdc.gsfc.nasa.gov/thumbnail/spacecraft/mars_polar_lander.gif Nozomi http://nssdc.gsfc.nasa.gov/thumbnail/spacecraft/planet_b.gif http://nssdc.gsfc.nasa.gov/thumbnail/spacecraft/planet_b.gif MOLA flat map of Mars: http://mars.jpl.nasa.gov/mgs/sci/mola/mola-may99.html Viking 1 orbiter http://nssdc.gsfc.nasa.gov/planetary/thumbnail/viking_spacecraft.gif http://mars.jpl.nasa.gov/mgs/sci/mola/mola-may99.html http://nssdc.gsfc.nasa.gov/planetary/thumbnail/viking_spacecraft.gif Image Credits

52. NASA: Viking 1 lander http://nssdc.gsfc.nasa.gov/thumbnail/spacecraft/viking_lander_model.gif http://nssdc.gsfc.nasa.gov/thumbnail/spacecraft/viking_lander_model.gif Phobos Mission http://nssdc.gsfc.nasa.gov/thumbnail/spacecraft/phobos_mars.gif http://nssdc.gsfc.nasa.gov/thumbnail/spacecraft/phobos_mars.gif Mars Pathfinder http://nssdc.gsfc.nasa.gov/planetary/thumbnail/marspath_sol65.gif http://nssdc.gsfc.nasa.gov/planetary/thumbnail/marspath_sol65.gif Mars Global Surveyor http://nssdc.gsfc.nasa.gov/planetary/banner/mgs_orbit_pic.gif http://nssdc.gsfc.nasa.gov/planetary/banner/mgs_orbit_pic.gif Mars Observer http://nssdc.gsfc.nasa.gov/thumbnail/spacecraft/mars_observer.gif http://nssdc.gsfc.nasa.gov/thumbnail/spacecraft/mars_observer.gif Mars Climate Orbiter http://nssdc.gsfc.nasa.gov/thumbnail/spacecraft/mars98orb.gif http://nssdc.gsfc.nasa.gov/thumbnail/spacecraft/mars98orb.gif 2001 Mars Odyssey http://mars.jpl.nasa.gov/odyssey/ http://mars.jpl.nasa.gov/odyssey/ Image Credits

53. ISAS: New Nozomi orbit http://www.planet-b.isas.ac.jp/index-e.html http://www.planet-b.isas.ac.jp/index-e.html Artist’s impression of Mars Express - ESA http://marsprogram.jpl.nasa.gov/express/gallery/artwork/images/35699_br.jpg Portion of Grand Canyon of Mars in 3D perspective - ESA/DLR/FU Berlin (G. Neukum) http://www.esa.int/export/externals/images/3D_large2.jpg Mars Exploration Rover - NASA http://marsrovers.jpl.nasa.gov/gallery/artwork/images/rover1_400.jpg Gusev Crater - NASA http://marsrovers.jpl.nasa.gov/gallery/landingsites/images/Gusev-plain_br.jpg Meridiani Planum - NASA http://marsrovers.jpl.nasa.gov/gallery/landingsites/images/Meridiani-plain_br.jpg Spirit Mars Exploration Rover Panorama - NASA http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20040112a/mspan_2X_final-A10R1_br.jpg Opportunity Mars Exploration Rover Panorama - NASA http://marsrovers.jpl.nasa.gov/gallery/press/opportunity/20040202a/MSPan_B1_2x-B009R1_br.jpg Image Credits

54. Now return to the Module 12 home page, and read more about space missions to Mars in the Textbook Readings. Hit the Esc key (escape) to return to the Module 12 Home Page

56. More information can be obtained about these Mars missions on the Internet at the following sites: The Viking Mission, http://nssdc.gsfc.nasa.gov/planetary/viking.htmlhttp://nssdc.gsfc.nasa.gov/planetary/viking.html The Phobos Project, http://nssdc.gsfc.nasa.gov/planetary/phobos.html Mars Observer, http://nssdc.gsfc.nasa.gov/nmc/tmp/1992-063A.html Mars Pathfinder, http://nssdc.gsfc.nasa.gov/planetary/mesur.html Mars Global Surveyor, http://mpfwww.jpl.nasa.gov/mgs/index.html Nozomi, http://nssdc.gsfc.nasa.gov/nmc/tmp/1998-041A.html Mars Climate Orbiter http://nssdc.gsfc.nasa.gov/nmc/tmp/1998-073A.html Mars Polar Lander http://nssdc.gsfc.nasa.gov/nmc/tmp/1999-001A.html

57. More information can be obtained about these Mars missions on the Internet at the following sites: 2001 Mars Odyssey http://marsprogram.jpl.nasa.gov/odyssey/http://marsprogram.jpl.nasa.gov/odyssey/ Mars Express http://www.esa.int/science/marsexpresshttp://www.esa.int/science/marsexpress Mars Exploration Rovers Mission http://marsrovers.jpl.nasa.gov/home/http://marsrovers.jpl.nasa.gov/home/ Details of past and future planned Mars missions can be found on the Internet at NASA’s Mars home page: http://nssdc.gsfc.nasa.gov/planetary/planets/marspage.htmlhttp://nssdc.gsfc.nasa.gov/planetary/planets/marspage.html together with a very useful timeline of all attempted and future Mars missions at: http://nssdc.gsfc.nasa.gov/planetary/chronology_mars.htmlhttp://nssdc.gsfc.nasa.gov/planetary/chronology_mars.html

58. Back to the Activity!