Mars Pathfinder
From Wikipedia, the free encyclopedia
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| Characteristics of the mission: | |
| Name | Mars Pathfinder |
| Nation | United States |
| Objective(s) | To land on Mars and perform Rover operations. |
| Craft | Mars Pathfinder |
| Craft – Weight | 870 kg |
| Administration and planning of mission |
JPL - NASA |
| Launch vehicle | Delta 7925 (#D240) |
| Date and time of launch |
4 December 1996 at 06:58:07 UTC |
| Launched from | ESMC / launch complex 17B |
| Scientific instruments/ Technology experiments |
Mars Pathfinder Lander:
Rover Sojourner:
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The Mars Pathfinder was launched on December 4, 1996 by NASA aboard a Delta II rocket, just a month after the Mars Global Surveyor was launched. After a 7-month voyage it landed on Ares Vallis, in a region called Chryse Planitia on Mars, on 4 July 1997. During its voyage the spacecraft had to accomplish four flight adjustments on 10 January, 3 February, 6 May and 25 June. The lander opened, exposing the rover called Sojourner (named after the famous American abolitionist Sojourner Truth) that would go on to execute different experiments on the Martian surface.
The mission carried a series of different scientific instruments to analyze the Martian atmosphere, climate, geology and the composition of its rocks and soil. It was the second project from NASA's Discovery Program, which promotes the use of low-cost spacecraft and frequent launches under the motto "cheaper, faster and better" promoted by the then administrator, Daniel Goldin. The mission was directed by the Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology, responsible for NASA's Mars Exploration Program.
This mission to Mars, besides being the first of a series of missions to Mars that included rovers (robotic exploration vehicles), was the most important since the Vikings landed on the red planet in 1976, and also was the first mission to send a rover to a planet. The Soviet Union succeeded in sending rovers, named Lunokhod 1 & 2 to the Moon in the 1970s.
Though completely successful and completing real objectives, the Mars Pathfinder mission can be regarded as a "proof-of-concept" for various technologies, such as airbag-mediated touchdown and automated obstacle avoidance, both later exploited by the Mars Exploration Rovers. The Mars Pathfinder was also remarkable for its extremely low price relative to other unmanned space missions. This was an important achievement, considering that approximately two-thirds of the spacecraft destined for Mars have either failed to launch or were lost en route.
[edit] Landing site
The landing site was an ancient flood plain in Mars' northern hemisphere called "Ares Vallis" and is among the rockiest parts of Mars. It was chosen because scientists found it to be a relatively safe surface to land on and one which contained a wide variety of rocks deposited during a possible catastrophic flood. Upon successful landing, the landing site was named The Carl Sagan Memorial Station in honor of the late astronomer and leader in the field of unmanned space exploration.
[edit] The probe
The probe consisted of a lander and a lightweight (10.6 kilograms/23 pounds) wheeled robot (Rover) called Sojourner ("one in a break from journeying"), after the sometime slave, abolitionist, and women's-rights activist Sojourner Truth. [1]
[edit] Landing process
Mars Pathfinder used an innovative method of directly entering Mars using an entry capsule, a supersonic parachute, followed by solid rockets and large airbags to cushion the impact.
[edit] Mission
The lander relayed transmissions to and from the robot, allowing it to operate independently of the probe body. The robot was remotely controlled, but had a basic camera-assisted autonomous control system allowing it to navigate and negotiate minor obstacles without operator intervention.
The robot's freedom of movement allowed the exploration team to closely analyze many more rocks and soil samples than with a traditional probe. From its landing in July 4, 1997 until the final data transmission on September 27, 1997, Mars Pathfinder returned 16,500 images from the lander and 550 images from the rover, as well as more than 15 chemical analyses of rocks and soil and extensive data on winds and other weather factors. Findings from the investigations carried out by scientific instruments on both the lander and the rover suggest that Mars was at one time in its past warm and wet, with water existing in its liquid state and a thicker atmosphere.
The lander and rover performed for much longer and better than expected, but eventually contact with the lander was lost on sol 83. The lander's silver-zinc battery was only capable of being recharged about 40 times, as a consequence after about 40 sols, the battery was not able to keep the lander warm at night. The exact reason for the final failure of the lander is not certain, but it was probably due to an electronics failure due to the very cold night-time temperatures that were experienced in the final weeks of the mission. After sol 92, the automatic backup procedures should have instructed the rover to return to the lander and circle it whilst attempting to re-establish communications. This behaviour would have continued until hardware failure. The lack of communication though means that the rover's final exact location and state are unknown. NASA's efforts to recontact Pathfinder ended on March 10, 1998.
[edit] Mission objectives
- To prove that the development of "faster, better and cheaper" spacecraft is possible (with three years for development and a cost under US$ 150 million).
- To show that it is possible to send a load of scientific instruments to another planet with a simple system and at one fifth the cost of a Viking mission.
- To demonstrate NASA's commitment to low-cost planetary exploration finishing the mission with a total expenditure of US$ 280 million, including the launch vehicle and mission operations.
[edit] Mission equipment
The Mars Pathfinder executed different investigations on the Martian soil using three scientific instruments. The lander contained a stereoscopic camera with spatial filters on an expandable pole called Imager for Mars Pathfinder (IMP)[1][2], and the Atmospheric Structure Instrument/Meteorology Package (ASI /MET)[3] which acts as a Mars metereological station, collecting data about pressure, temperature, and winds. The Sojourner rover had a Alpha Proton X-ray Spectrometer (APXS)[4], which was used to analyze the components of the rocks and soil. The rover also had two black and white cameras and a color one. These instruments could make investigations of the geology of the Martian surface from just a few millimeters to many hundreds of meters, the geochemistry and evolutionary history of the rocks and surface, the magnetic and mechanical properties of the land, as well as the magnetic properties of the dust, atmosphere and the rotational and orbital dynamics of the planet.
[edit] Scientific objectives
- Surface morphology and geology using scaled measurements.
- Petrology and geochemistry of surface materials.
- Magnetic and mechanical properties of the surface.
- Atmospheric structure, besides diurnal and nocturnal metereological variations.
- Rotational and orbital dynamics of Mars.
[edit] Mission stages: entry, descent and landing
Mars Pathfinder directly entered Mars atmosphere in a retrograde direction from a hyperbolic trajectory at 6.1 km/s using an atmospheric entry aeroshell (capsule) that was derived from the original Viking lander design. The aeroshell consisted of a back shell and a specially designed ablative heatshield to slow to 370 m/s (830 MPH) where a supersonic parachute was inflated to slow its descent through the thin Martian atmosphere to 68 m/s (about 160 MPH). Twenty seconds later the heatshield was pyrotechnically released. Another twenty seconds later the lander separated and lowered from the backshell on a 20 m bridle (tether), a radar was used by the lander to determine altitude and descent velocity below 1.6 km above the surface. Airbags were inflated in less than a second using three gas generators when the lander was 355 m above the ground.
The airbags were made of 4 inter-connected multi-layer vectran bags that surrounded the tetrahedron lander. They were designed and tested to accommodate grazing angle impacts as high as 28 m/s. However, as the airbags were designed for no more than about 15 m/s vertical impacts, three solid retrorockets were mounted above the lander in the backshell. These were fired at 98 m above the ground. The lander's on-board computer estimated the best time to fire the rockets and cut the bridle so that the lander velocity would be reduced to 0 m/s between 15 and 25 m above the ground. After 2.3 seconds, while the rockets were still firing, the lander cut the bridle loose about 21.5 m above the ground and fell to the ground. The rockets flew up and away with the backshell and parachute (they were not sighted by the lander nor by any orbiter since). The lander impacted at 14 m/s and limited the impact to only 18 gees of deceleration and bounced at least 15 times (the first bounce was 15.7 m high). The whole entry, descent and landing (EDL) process was completed in 4 minutes.
Once the lander stopped rolling, the airbags deflated and retracted toward the lander using four winches on the lander "petals". Designed to right itself from any initial orientation, the lander happened to roll right side up onto its base petal. 74 minutes after landing, the petals were deployed with Sojourner rover and the solar panels attached on the inside. The lander arrived at night at 2:56:55 Mars local solar time (16:56:55 UTC) on July 4, 1997. The lander had to wait until sunrise to send its first digital signals and images to Earth. The landing site was located at 19.30° north latitude and 33.52° west longitude in Ares Vallis, only 19 kilometres southwest of the center of the 200 km wide landing site ellipse. During Sol 1 –or martian days– the lander took pictures and made some metereologic measurements. Once the data was received, the engineers realized that one of the airbags hadn't fully deflated and could be a problem for the forthcoming traverse of Sojourner's descent ramp. To solve the problem, they sent commands to the lander to raise one of its petals and perform additional retraction to flatten the airbag. The procedure was a success.
[edit] The Sojourner gets out
Sojourner's exit from the lander occurred on Sol 2. As the next sols progressed it approached some rocks which were named (by the scientists) "Barnacle Bill", "Yogi", and "Scooby Doo", after the famous cartoons. The rover made measurements of the elements found in those rocks and in the martian soil, while the lander took pictures of the Sojourner and the surrounding terrain, besides making climate observations.
The Sojourner was a six-wheeled vehicle and it was 65 cm long, 48 cm wide, 30 cm tall and weighed 10.6 kg. It could move about 500 metres from the lander and its maximum speed reached one centimeter per second. During its 83 sols of operation, it sent 550 photographs to Earth and analyzed the chemical properties of sixteen locations near the lander.
[edit] Sojourner's rock analysis
The first analysis on a rock started on Sol 3 with "Barnacle Bill". The Alpha Proton X-ray Spectrometer (APXS) was used to determine its composition, the spectrometer taking ten hours to make a full scan of the sample. It found all the elements except hydrogen, which constitutes just one tenth of 1% of the rock's or soil's mass.
The APXS works by irradiating rocks and soil samples with alpha particles (helium nuclei, which consist of two protons and two neutrons). The results indicated that "Barnacle Bill" is much like Earth's andesites, confirming past volcanic activity.
Analysis of "Yogi" rock again using the APXS showed that it was a basaltic rock, more primitive than "Barnacle Bill". Yogi's shape and texture show that it was probably deposited there by a flood.
Another rock, named "Moe", was found to have certain marks on its surface, demonstrating erosion caused by the wind. Most rocks analyzed showed a high content of silicon. In another region known as Rock Garden the Sojourner encountered crescent Moon-shaped dunes, which are similar to crescentic dunes on Earth.
The lander, on the other hand, sent more than 16,500 pictures and made 8.5 million measurements of the atmospheric pressure, temperature and wind speed.
Video footage of Sojouner approaching "Yogi", including the photograph in this section, used in the opening credits of Star Trek: Enterprise made that television program the first science fiction television or film production in history to use images taken on another planet.
[edit] End of the mission
Although the mission was programmed to last a week to a month, it eventually lasted for almost 3 months. The final contact with the Pathfinder was at 10:23 UTC on September 27, 1997. Although the mission planners tried to restore contact during the following five months, the successful mission was terminated on March 10, 1998. After the landing, the Mars Pathfinder was renamed as the Sagan Memorial Station in honor of the famous astronomer and planetologist Carl Sagan. The mission had exceeded its goals in the first month.
The Mars Pathfinder entry descent and landing system design was used (with some modification) on the Mars Exploration Rover mission. Likewise many design aspects of Sojourner rover (e.g. the rocker-bogie mobility architecture and the navigation algorithms) were also successfully used on the Mars Exploration Rover mission.
[edit] Facts
- In June of 1997, Mattel released a Hot Wheels toy vehicle based on the Mars Pathfinder and Mars Sojourner rover, in cooperation with NASA's Jet Propulsion Laboratory. The toy was sold through major retailers such as Toys 'R' Us and Walmart.
- In 2003, the Sojourner Rover was inducted into the Robot Hall of Fame.
[edit] See also
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Wikimedia Commons has media related to: |
- Exploration of Mars
- Mars Exploration Rovers (2003-present mission)
- Space exploration
- Atmospheric reentry
[edit] Disambiguation
In sociology, sojourner is a portmanteau that refers to a "solo journeyer" working in a foreign country with the intention to return to the homeland after a period of time.
[edit] References
- ^ Smith, P. H.; Tomasko, M. G.; Britt, D.; Crowe, D. G.; Reid, R.; Keller, H. U.; Thomas, N.; Gliem, F.; Rueffer, P.; Sullivan, R.; Greeley, R.; Knudsen, J. M.; Madsen, M. B.; Gunnlaugsson, H. P.; Hviid, S. F.; Goetz, W.; Soderblom, L. A.; Gaddis, L.; Kirk, R. (1997). "The imager for Mars Pathfinder experiment". Journal of Geophysical Research 102 (E2): 4003-4026. DOI:10.1029/96JE03568).
- ^ Smith P. H., Bell J. F., Bridges N. T., (1997). "Results from the Mars Pathfinder camera". Science 278 (5344): 1758-1765.
- ^ Schofield J. T., Barnes J. R., Crisp D., Haberle R. M., Larsen S., Magalhaes J. A., Murphy J. R., Seiff A., Wilson G. (1997). "The Mars Pathfinder atmospheric structure investigation meteorology (ASI/MET) experiment". Science 278 (5344): 1752-1758.
- ^ R. Rieder, H. Wänke, T. Economou, A. Turkevich (1997). "Determination of the chemical composition of Martian soil and rocks:The alpha proton X ray spectrometer". J. Geophysical Research 102: 4027-4044.
- This article draws heavily on the corresponding article in the Spanish-language Wikipedia, which was accessed in the version of 28 March 2005. It was translated by the Spanish Translation of the Week collaboration.
- JPL Mars Pathfinder article
- Mars Pathfinder Litograph Set, NASA. (1997)
- Poster: Mars Pathfinder –Roving the Red Planet, NASA. (1998)
- Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000, Asif A. Siddiqi. Monographs in Aerospace History, #24. June 2002, NASA History Office.
- "Return to Mars", article by William R. Newcott. National Geographic, pp. 2-29. Vol. 194, 2nd edition - August 1998.
- "La misión Pathfinder –rebautizada Carl Sagan Memorial Station, en memoria del célebre astrónomo-, paso a paso todo Marte", de J. Roberto Mallo. Conozca Más, págs. 90-96. Edición número 106 - agosto de 1997.
- "Un espía que anda por Marte", de Julio Guerrieri. Descubrir, págs. 80-83. Edición número 73 - agosto de 1997.
- "Mars Pathfinder: el inicio de la conquista de Marte" EL Universo, Enciclopedia de la Astronomía y el Espacio, Editorial Planeta-De Agostini, págs. 58-60. Tomo 5. (1997)
- Sojourner: An Insider's View of the Mars Pathfinder Mission, by Andrew Mishkin, Senior Systems Engineer, NASA Jet Propulsion Laboratory. ISBN 0-425-19199-0
- Experiences with operations and autonomy of the Mars Pathfinder microrover, A. H. Mishkin, J. C. Morrison, T. T. Nguyen, H. W. Stone, B. K. Cooper and B. H. Wilcox. In Proceedings of the IEEE Aerospace Conference, Snowmass, CO 1998.
[edit] Bibliography on Mars
- The New Solar System, J. Kelly Beatty, Carolyn Collins Petersen, Andrew Chaikin. Cambridge University Press; 4 edition (1998); ISBN 0-521-64587-5
- The Surface of Mars, Michael H. Carr. Yale University Press, New Haven; 1 edition (1981); ISBN 0-300-02750-8, ISBN 0-300-03242-0
- Exploring the Planets, Eric H. Christiansen, Kenneth W. Hamblin. Prentice-Hall, Englewood Cliffs, New Jersey; 2 edition (1995); ISBN 0-02-322421-5
- The Search for Life on Mars: Evolution of an Idea, Henry S.F. Cooper. Holt, Rinehart, and Winston, New York (1980); ISBN 0-03-046166-9 (hardcover), ISBN 0-03-059818-4
- Mars, Percival Lowell. Houghton, Mifflin, Boston, New York (1895). Kessinger Publishing (2004); ISBN 1-4191-3284-9
- Journey Into Space: The First Thirty Years of Space Exploration, Bruce Murray. W.W. Norton, New York (1989); ISBN 0-393-02675-2 (hardcover), ISBN 0-393-30703-4
- Planets & Perception: Telescopic Views and Interpretations, 1609-1909, William Sheehan. University of Arizona Press, Tucson (1988); ISBN 0-8165-1059-8
- The Planet Mars: A History of Observation and Discovery, William Sheehan. University of Arizona Press, Tucson (1996); ISBN 0-8165-1640-5 (hardcover), ISBN 0-8165-1641-3
- The Martian Landscape, Viking Lander Imaging Team. NASA SP-425 (1978)
- Viking Orbiter Views of Mars, Viking Orbiter Imaging Team. NASA SP-441 (1980)
- Mars Beckons, John Noble Wilford. ISBN 0-394-58359-0 (hardcover, 1 edition, 1990), ISBN 0-679-73531-3 (1991), ISBN 0-517-19803-7 (1997)
[edit] External links
- Mars Pathfinder
- NASA Office of Space Science
- JPL - Mars Exploration Rover Mission
- What really happened on Mars? — discussion of the software problems on the Pathfinder spacecraft
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| Flybys: Mariner 4 | Mariner 6 | Mariner 7 | Mars 4 | |
| Orbiters: Mariner 9 | Mars 2 | Mars 3 | Mars 5 | Mars 6 | Viking 1 | Viking 2 | Phobos 2 | Mars Global Surveyor | Mars Odyssey | Mars Express Orbiter | Mars Reconnaissance Orbiter | |
| Landers and Rovers: Mars 3 | Viking 1 | Viking 2 | Mars Pathfinder | Spirit rover | Opportunity rover | |
| Future: Phoenix Scout (2007) | Mars Science Laboratory (2009) | Phobos-Grunt (2009) | Mars 2011 | ExoMars (2013) | Astrobiology Field Laboratory (2016?) | |
| See also: Mars | Exploration of Mars | Colonization of Mars | |
