[FPSPACE] FW: [New post] The Lure of the Red Planet: Follow the Water
ljk4 at msn.com
Thu Dec 29 08:59:16 EST 2011
Date: Thu, 29 Dec 2011 13:00:18 +0000
To: ljk4 at msn.com
From: donotreply at wordpress.com
Subject: [New post] The Lure of the Red Planet: Follow the Water
New post on Roger Launius's Blog
The Lure of the Red Planet: Follow the Water
Perhaps by using the “follow the water” strategy humanity may someday find sand-laden jets shooting into the polar sky as depicted in this view by noted space artist Ron Miller. It shows the Martian south polar ice cap as southern spring begins.
The robotic probes first sent to Mars found a planet far different from that envisioned in Western popular culture. Humanity had envisioned a world filled with some type of life, perhaps only plants, but it found a desert, rocky surface. Planetary scientist and JPL director Bruce Murray noted that public expectations to find evidence of life on the red planet devastated any desire to return to Mars for more than two decades. While there were planning exercises for missions to Mars, none from the U.S. actually flew until the 1990s.
One important change in the interest registered about Mars came in August 1996 when a team of NASA and Stanford University scientists announced that a Mars meteorite found in Antarctica contained possible evidence of ancient Martian life. When the 4.2-pound, potato-sized rock (identified as ALH84001) was formed as an igneous rock about 4.5 billion years ago, the scientists believed that Mars was much warmer and probably contained oceans hospitable to life. Then, about 15 million years ago, a large asteroid hit the red planet and jettisoned the rock into space, where it remained until it crashed into Antarctica around 11,000 B.C.E. Scientists presented three suggestive, but far from conclusive, pieces of evidence suggesting that fossil-like remains of Martian microorganisms, which date back 3.6 billion years, might be present in ALH84001. While there is no consensus on the truth of these findings, they did lead to added support for an aggressive set of missions to Mars to help discover the truth.
Thereafter the strategy for much of Mars exploration has been built upon the motto, “Follow the Water.” In essence, this approach noted that life on Earth is built upon liquid water and that any life elsewhere would probably have chemistries built upon these same elements. Accordingly, to search for life on Mars, past or present, NASA’s strategy must be to follow the water. If scientists could find any liquid water on Mars, probably only deep beneath the surface, the potential for life to exist was also present.
Liquid water on the surface of Mars? So it would seem from this photograph. This image from the Mars Global Surveyor shows a portion of the wall and floor of an ancient impact crater in the southern cratered terrain of Noachis Terra. It also shows a smooth, dark surface on the crater floor that many think is the remains of a pond or lake.
The Mars of today, without any evidence of water whatsoever on the surface, probably had water flowing freely in its ancient history. Evidence of changes to the planet’s surface from fast flowing water has been collected by many space probes orbiting the planet since the latter 1990s. The spacecraft to open this possibility was Mars Global Surveyor, reaching the planet in 1998 and a new and exciting era of scientific missions to study the red planet. Its recent discoveries offer titillating hints for learning about the possibility of life on Mars, at least in the distant past. In an exciting press conference in June 2000, astronomer Michael Malin discussed his analysis of imagery from Mars Global Surveyor, a stunningly successful NASA probe. He showed more than 150 geographic features all over Mars probably created by fast flowing water. He suggested that there might actually be water in the substrata of Mars, and our experience on Earth has indicated that where water exists life as we understand it exists as well.
Operating for several years, Mars Global Surveyor continued to send back views of the Martian surface that seemed to show evidence of dry riverbeds, flood plains, gullies on Martian cliffs and crater walls, and sedimentary deposits that suggested the presence of water flowing on the surface at some point in the history of Mars. This led scientists to theorize that billions of years ago, Earth and Mars might have been very similar places. Of course, Mars lost its water and the question of why that might have been the case has also motivated many Mars missions to the present. At that point, a consensus emerged that on any mission to Mars we should “follow the water” and seeking the answer to the ultimate question: “Are we alone in the universe?” Mars may well provide a definite answer.
At present, most scientists believe the odds are almost nonexistent that complex life forms could have evolved on Mars because of its extremely hostile environment. The stories of “advanced civilizations,” as proposed by Percival Lowell, or “little green men” are just that, stories. But many scientists believe there is sufficient evidence to think that microscopic organisms might once have evolved on the planet when it was much warmer and wetter billions of years ago. There are even a few scientists who would go somewhat further and theorize that perhaps some water is still present deep inside the planet. In that case simple life forms might still be living beneath Mars’ polar caps or in subterranean hot springs warmed by vents from the Martian core. These might be Martian equivalents of single-celled microbes that dwell in Earth’s bedrock. Scientists a quick to add, however, that these are unproven theories for which evidence has not yet been discovered.
This schematic shows the Opportunity rover as it was at the time it flew to Mars in 2004.
This strategy of “follow the water” has dominated all planning for Mars science missions for more than a decade and results thus far have been promising. Scientists continue to plan an integrated set of missions to continue this strategy. These major missions have been undertaken to learn more about Mars:
Mars Pathfinder - USA Lander & Surface Rover - 870 kg - (4 December 1996): The inexpensive Mars Pathfinder (costing only $267 million) landed on Mars on 4 July 1996, after its launch in December 1996. A small, 23-pound, six-wheeled robotic rover, named Sojourner, departed the main lander and began to record weather patterns, atmospheric opacity, and the chemical composition of rocks washed down into the Ares Vallis flood plain, an ancient outflow channel in Mars' northern hemisphere. This vehicle completed its projected milestone 30-day mission on 3 August 1997, capturing far more data on the atmosphere, weather, and geology of Mars than scientists had expected. In all, the Pathfinder mission returned more than 1.2 gigabits (1.2 billion bits) of data and over 10,000 tantalizing pictures of the Martian landscape. The images from both craft were posted to the Internet, to which individuals turned for information about the mission more than 500 million times through the end of July. The mission's primary objective is to demonstrate the feasibility of low-cost landings on the martian surface. This was the second mission in NASA's low-cost Discovery series. (Successful)
Mars Polar Lander-USA lander - 538 kg - (3 January 1999): and its attached Deep Space 2 probes were launched on a Delta II rocket which placed them into a low-Earth parking orbit. The third stage fired for 88 seconds to put the spacecraft into a Mars transfer trajectory. Trajectory correction maneuvers were performed on 21 January, 15 March, 1 September, 30 October, and30 November 1999. After an 11-month hyperbolic transfer cruise, the Mars Polar Lander reached Mars on3 December 1999. The lander was to make a direct entry into Mars' atmosphere at 6.8 km/s but was lost during the landing sequence. JPL lost contact with the spacecraft and due to lack of communication, it is not known whether the probe followed the descent plan or was lost in some other manner. (Unsuccessful)
Mars Exploration Rover A - USA Mars Rover - 827 kg – (10 June 2003): Named “Spirit” upon landing on the Martian surface on 4 January 2004 this rover was one of a pair launched to Mars in mid-2003. Equipped with a battery of scientific instruments it was intended to operate for 90 days, until April 2004, and to traverse about 100 meters a day. The scientific goals of the rover missions are to gather data to help determine if life ever arose on Mars, characterize the climate of Mars, characterize the geology of Mars, and prepare for human exploration of Mars. It has performed exceptionally well and is still operating. A primary mission objective was to search for geological clues to the environmental conditions that existed when liquid water was present and assess whether those environments were conducive to life. It landed in Gusev Crater because it had the appearance of a crater lakebed. The rover’s scientific data suggests that Gusev may have at one time been filled with water. (Successful)
Mars Exploration Rover B- USA Mars Rover - 827 kg – (7 July 2003): Named “Opportunity” upon landing on the Martian surface on 25 January 2004 this rover was the second of a pair launched to Mars in mid-2003. It carried identical instruments to “Spirit” and landed at Terra Meridiani, also known as the “Hematite Site” because it displays evidence of coarse-grained hematite, an iron-rich mineral which typically forms in water. This mission has also continued into 2011. (Successful)
Phoenix Mars Lander - USA Mars Lander - 350 kg – (4 August 2007): The Phoenix Mars Lander is designed to study the surface and near-surface environment of a landing site in the high northern area of Mars. The primary science objectives for Phoenix are to: determine polar climate and weather, interaction with the surface, and composition of the lower atmosphere around 70 degrees north for at least 90 sols; determine the atmospheric characteristics during descent through the atmosphere; characterize the geomorphology and active processes shaping the northern plains and the physical properties of the near-surface regolith focusing on the role of water; determine the aqueous mineralogy and chemistry as well as the adsorbed gases and organic content of the regolith; characterize the history of water, ice, and the polar climate and determine the past and present biological potential of the surface and subsurface environments.Phoenix was launched on 4 August 2007 on a Delta II 7925 from Cape Canaveral Air Force Station,Florida. The 681 million km heliocentric cruise to Mars takes approximately 10 months, with landing on Mars on 25 May 2008. (Successful)
Mars Science Laboratory, “Curiosity,” (MSL) – USA Mars Rover – 750 kg – (26 November 2011). Launched at 10:02 EST, the objective of Curiosity was to explore the Martian Habitat as a former or current habitat for life, and as such, it would operate for a full Martian year, or 687 earth days. MSL has eight scientific objectives: determine the nature and inventory of organic compounds, inventory the chemical building blocks needed for life, identify features that reflect biological processes, investigate the Martian surface and near surface geological features, interpret the processes that have formed rocks and soils, assess long-timescale atmospheric evolution processes, determine the present state and distribution of water and carbon dioxide, and characterize the spectrum of surface radiation. After leaving earth’s orbit, The Rover will travel eight months to reach Mars, landing in August of 2012. There are four possible landing sites, from which MSL will travel 20 to 70 km to collect 70 rock and soil samples. (Undetermined).
launiusr | December 29, 2011 at 12:24 pm | Tags: Bruce Murray, Follow the Water, Mars exploration, Mars Pathfinder, Mars Phoenix, Mars Science Laboratory, NASA, Oportunity, Percival Lowell, Spirit, U.S. Civil Space
| Categories: History, Science, Space
| URL: http://wp.me/pwYu1-GJ
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