<body bgcolor="#ffffff" text="#000000" link="#0000ff" vlink="#0000ff"> <h2><center><font color=green> <center>IS THE MARTIAN SCENARIO SUPPORTED: CURRENT AND PAST CONDITIONS ON MARS</center></font> <p><p><center> <table border=8 cellpadding=10 bgcolor=magenta> <tr><td><img width=700 src="lush_mars.png"><p> <img width=700 src="curiosity_gale.png"></td> <td width=800><ul><h2>Astronomers suggest that in the past Mars had a much thicker atmosphere than today (upper left: artist's conception) and was much more earth-like (there are models which suggst that the young Mars had an atmospheric pressure of 2 bars, 1.01 bar is 1 atmosphere). This is interesting because, today, the atmospheric conditions on Mars are such that liquid water cannot exist on the surface of Mars (lower left: Curiosity panoramic picture of Gale crater).<p><center> <font color=green>Is there evidence that in the past, Mars may have had an atmosphere that was much more conducive to <font color=blue>Life As We Know It (LAWKI)?</font></font></center> <p> Here, we do three things:<font color=green><p><ul> <li>We look at the evidence for water on Mars today<p> <li>We look at the evidence that Mars once had a thicker atmosphere and supported quiescent liquid water, such as in rivers and lakes in the past <p> <li>We look at two past attempts to find current or past life on Mars: Viking Biology experiments, Allan Hills meteorite </ul></font></td></tr></table></center> <p><hr><p> <center><font color=green>LANDERS AND THEIR LANDING SITES</font></center><p> <center><table border=6 cellpadding=8><tr> <td width=700><ul><img width=620 src="Mars_topography.jpg"><p> <a target="_blank" href="Mars-landing-sites.png"> <img width=540 src="Mars-landing-sites.png"></a></ul></td> <td width=800><ul><h2>This highlights a large problem we have with exploring Mars using landers. We place the landers in selected spots. We can explore a little in the vicinity of the spots using rovers and helicopters, but not a lot. <p> The latest rover in Jezero crater, <font color=magenta>Perseverance, </font> is fast, but moves only at 0.1 miles per hour (4.2 cm/sec). The lunar rover was designed for a top speed of 8 miles per hour but was driven by Eugene Cernan at 11.2 miles per hour. <p> There is a helicopter that accompanies Perseverance, <font color=magenta>Ingenuity</font>, which flies at speeds of up to 12.3 miles per hour with a range of 0.44 miles at altitudes up to 12 meters.</td> <td><img width=800 src="perseverance_jpl.png"><p><center> Perseverance being prepared in lab at JPL</center></td> </tr></table></center> <center> <table border=6 cellpadding=8> <tr><td><img width=600 src="perseverance_1.jpeg"></td> <td><img width=600 src="perseverance_route.jpg"> <p><h2><center> <a target="_blank" href="https://mars.nasa.gov/mars2020/">Perseverance and Ingenuity</a> travels in Jezero crater</center></td></tr> <tr><td><img width=600 src="curiosity_route.jpg"></td> <td><img width=600 src="curiosity_1.jpg"><p> <h2><center> <a target="_blank" href="https://mars.nasa.gov/msl/home/">Curiosity</a> and its travels around Gale crater</center></td></tr> </table> <center> <a target="_blank" href="https://mars.nasa.gov/technology/helicopter/#"> <table border=6 cellpadding=8> <tr><td><img width=600 src="inegenuity_1.jpg"></td> <td><img width=600 src="ingenuity_2_gif.gif"></td></tr> <tr><td><img width=600 src="ingenuity_3.jpg"></td> <td><img width=600 src="ingenuity_4.jpg"></td></tr> </table></a></center> <p><hr><p> <font color=green><center>I. CURRENT MARS</center></font><p> <center><table border=6 cellpadding=8><tr><td><center> <img width=940 src="mars_panorama.jpg"> <img width=900 src="jezero_relief.jpeg"> </center><p> <center><h2>The view of Mount Sharp in Gale crater from Curiosity (left panel). On the right panel, you can see where Curiosity landed and the route it followed in Gale crater. Gale crater is an old basin, 3.6 to 3.8 billion year old. Gale crater is about 150 kilometers in diameter. It is the lowest spot on Mars for over 1,000 kilometers. Mount Sharp rises 5.5 kilometers above the crater floor. Sediments in Gale crater which stopped accumulating 3.1 to 3.8 billion years ago, show that there was abundant flowing water and a lake that existed for tens of thousands of years (if not millions of years) in Gale crater. </center></td></tr></table></center> <p><hr><p> <center><font color=green> Current Conditions at Gale Crater</font><p> <table border=6 cellpadding=8><tr> <td width=200><a target="_blank" href="mars_weather_report.jpg"> <img width=600 src="mars_weather_report.jpg"></a></td> <td width=300><center><img width=500 src="water_phase_diagram_mars.jpeg"><p><h2> Phase Diagram for Water<p> </center><ul><h2> Mars currently has a low temperature, from below the freezing point of water on Earth, ~0<sup>o</sup>C (32 F), to nealy -60<sup>O</sup>C (-120 F), and very low atmospheric pressure, less than 1 % than that for the Earth. Can see on the phase diagram for water that Mars currently cannot support liquid water on its surface except under extreme conditions.</center> </td> </tr></table></center> </ul></ul></ul> <p><hr><p> <p> <center><font color=green> II. MARS AND WATER </font></center></center> <p> </center> We see plenty of evidence that there is water on Mars. There is just no evidence that liquid water currently exists in large amounts on Mars. For example, <font color=magenta>there is water in the residual polar ice caps on Mars: <p><table border=6 cellpadding=8><tr> <td> <img width=540 src="http://pages.uoregon.edu/~imamura/121/images/mars060.gif" width=400> <p> <h2>The polar caps on Mars have two parts; regions that show seasonal variations and residual caps. The seasonal caps are thought to be composed of frozen carbon dioxide. The residual caps are smaller and brighter than the seasonal caps and are mainly water ice in the north and water ice with a veneer of carbon dioxide ice in the south. The residual caps contain roughly the same amounts of water ice. The northern residual cap (right hand pictures) is around 1,000 kilometers in diameter and has thickness of about 2 kilometers, if uniformly spread. This is about 60 % as much ice as contained in the Greenland ice sheets. The southern residual polar cap is roughly 1/3 in extent compared to the northern polar cap but is thicker and contains about as much water ice as does the northern residual polar cap. </td> <td> <center> <img width=900 src="Mars_north_pole.jpg"></center> <img width=900 src="mars_north_polar_cap_ice_ages.jpeg"></center><h3> <p><center>The above is a cross-section of Mars's northern polar ice cap (taken with Shallow Radar on NASA's Mars Reconnaissance Orbiter MRO). The top 100-m to 300-m layers of ice show evidence of changes between ice age and inter-glacial periods. (Image credit: Southwest Research Institute)</center></td> </tr></table></font><p><hr><p> In addition to the water in the northern residual polar caps, there is also evidence for water in the low-lying clouds above canyons, and in large glaciers lying scattered rocky debris:<p> <table cell border=10 cell padding=10 bgcolor=aqua><tr> <td> <img src= "http://pages.uoregon.edu/~imamura/121/images/mars_clouds_viking_big.jpg"> <h2><p><center>Clouds Above Canyons</center> </td> <td> <center><img src= "http://pages.uoregon.edu/~imamura/121/images/glacier-browse.jpg"></center> <p><h2><center>Glaciers on Mars</center><p> <h2><ul> Huge glaciers up to half a mile thick which lie close to the equator of Mars are thought to be the remnants of an ice age on Mars. It is thought that the glaciers formed up to 100 million years ago and represent evidence of climate change on Mars. Hundreds of glaciers have been identified by researchers using ground-penetrating radar which allows them to see through the rocky layers of debris covering the ice. The largest glacier is 13 miles long and more than 60 miles wide. It could be a source of water for astronauts on Mars. When the glaciers formed, Mars' climate was much colder because the angle Mars' spin axis makes with its orbital axis was much greater than it is now (see <a target="_blank" href=" https://climate.nasa.gov/ask-nasa-climate/2949/why-milankovitch-orbital-cycles-cant-explain-earths-current-warming/#:~:text=Milankovitch%20cycles%20include%20the%20shape,is%20pointed%20(its%20precession)"> Milankovitch cycles</a>). This allowed ice sheets to extend far beyond the polar regions and towards, possibly even reaching, the Equator. </h3></td> </tr></table></center> <p><hr><p> There is also a <i>permafrost</i> layer on Mars today as implied by <a href="http://pages.uoregon.edu/~soper/ImMars/outflow.gif"> Outflow Channels</a> (large channels which can be up to 100 kilometers and thousands of kilometers long--likely formed by catastrophic flooding), <a href="http://pages.uoregon.edu/~imamura/121/images/islands.gif"> "Islands"</a>, and <a href="http://pages.uoregon.edu/~imamura/121/images/splosh.gif"> Splosh Craters</a> (oozing mud formed by impacts which melted the permafrost layer). The outflow channels and islands were produced by massive floods on Mars. Presumably what happened was that some event (possibly the impact of a large object) caused a rapid, large-scale melting of the permafrost layer which caused floods. <p><font color=green><center> There is ample evidence that water exists on Mars much of it below the surface which can be melted and lead to transient flows.</font></center> <p> The question of <font color=magenta>how much water is left on Mars?</font> is still open, however. Has most of it been stripped, as is thought for the CO<sub>2</sub>, or is most of it tied up in ice and/or the crust? The question can be answered by the deuterium-to-hydrogen ratio (D/H), as was done for Venus. On Mars, the (D/H) ratio is around 5 times larger than that found on Earth; on Venus the (D/H) ratio is 120 times larger than that found on Earth. The large (D/H) ratio on Venus suggests Venus has lost more than 99.9 % of its water. On Mars, the (D/H) ratio is smaller and suggests that Mars has lost less water, but still, Mars has lost more than three-quarters of its water. A lot has been lost, but there still is likely to be a lot of water left to tap on Mars. <p><hr><hr><p><h2><center><font color=green> III. IS THERE EVIDENCE FOR A MORE HOSPITABLE CLIMATE IN THE PAST? </font></center><p> There was indeed evidence that in the past <a href="http://pages.uoregon.edu/~imamura/121/images/network.gif"> water existed in liquid form </a> on the surface of Mars under quiescent conditions, even before the current generation of Martian landers, rovers, and helicopters. There were thus strong hints that grossly different atmospheric conditions on existed on Mars in the past than currently exist width=700 and thus hope that life had existed on Mars in the past. <p> This picture has been sharpened many-fold in the last twenty years with our current landers and rovers.</h3> </h2><h2><p> <center> <table border=6 cellpadding=8 bgcolor=magenta> <tr><td width=400> <h2> <center> <font color=green>Curiosity</font>, launched on Nov 26, 2011 reached Mars on Aug 5, 2012 (landing in <a href="http://pages.uoregon.edu/~imamura/121/images/1024px-MSL_landing_sites_topograph.png"> Gale crater</a>), has carried on the fine work of the earlier rovers, <font color=green>Spirit</font> (2005-2010) and <font color=green>Opportunity</font> (2005-2018) exploring at the break-neck maximum speeds of 5 cm per second. A person walking at 3 miles per hour is moving at 134 cm per second! This year, <font color=green>Curiosity</font> was joined by <font color=green>Perseverance</font> (rover) and <font color=brown>Ingenuity</font> (helicopter).<p> <a href="http://pages.uoregon.edu/~imamura/121/images/ curiosity-mars-rover-self-portrait-martian-sand-dunes-pia20316-br2.jpg "> <img width=400 src="http://pages.uoregon.edu/~imamura/121/images/ curiosity-mars-rover-self-portrait-martian-sand-dunes-pia20316-br2.jpg "></a> <br> <a href="http://pages.uoregon.edu/~imamura/121/images/ pia16051_figure_1_raw_smaller-full.jpg "> <img width=400 src="http://pages.uoregon.edu/~imamura/121/images/ pia16051_figure_1_raw_smaller-full.jpg "></a> <a href="http://pages.uoregon.edu/~imamura/121/images/ pia20332-figa_sol1302_ml_mcam06191_w_labels-cr.jpg "> <img width=400 src="http://pages.uoregon.edu/~imamura/121/images/ pia20332-figa_sol1302_ml_mcam06191_w_labels-cr.jpg "></a> </td> <td width=800><a href="http://mars.nasa.gov/programmissions/science/goal1"> <a href="http://pages.uoregon.edu/~imamura/121/images/ NASA-Curiosity-Rover-Top-Science-Discoveries.png"> <img width=800 src="http://pages.uoregon.edu/~imamura/121/images/ NASA-Curiosity-Rover-Top-Science-Discoveries.png"></a></td> </tr></table> <p><hr><p> <center><table border=8 cellpadding=6 bgcolor=magenta> <tr> <td><center> <a href=" Curiosity_bagnold_dune_filed.jpg"> <img width=530 src=" Curiosity_bagnold_dune_filed.jpg"></a> </center> </td> <td><center> <a href=" curiosity_mesas_eorded.jpg"> <img width=400 src=" curiosity_mesas_eorded.jpg"></a></center> </td> <td><center> <a href=" curiosity_kimberley_formation.jpg"> <img width=570 src=" curiosity_kimberley_formation.jpg"></a></center> </td> </tr> <tr> <td> <h2><center>Sand Dunes</center><p><h3> These no-drag ripples change in size depending on the density of the medium moving the grains. That medium is Mars's atmosphere. By studying wind-drag ripples preserved in Martian sandstone, scientists have found evidence that the planet lost most of its atmosphere early in its history. <td> <h2><center>"Mesas, Buttes"</center><p><h3> Formed over millions of years due to weathering and erosion, buttes tend to be tall, flat-topped, and steep-sided, and appear to form from larger mesas or plateaus. Found on Earth as well, the only real difference between a mesa and a butte is the size, a butte is taller than it is wide, while a mesa is a much larger, slightly less elevated feature. The buttes and mesas rising above the surface in the Murray Buttes region are thought to be the eroded remains of ancient Martian sandstone. </td> <td> <center><h2>Dried Lake Beds</center><p><h3> A view from the "Kimberley" formation on Mars. The strata in the foreground dip towards the base of Mount Sharp, a mountain that formed in the middle of Gale crater. This is the ancient depression that existed before the larger bulk of the mountain formed. A series of long-lived streams and lakes existed at some point between about 3.8 to 3.3 billion years ago, delivering sediment that slowly built up the lower layers of Mount Sharp. </td> </tr> </table></center> <p><hr><p> <center><table border=8 cellpadding=6 bgcolor=magenta> <tr> <td><center> <a href=" curiosity_masthead.jpg"> <img width=530 src=" curiosity_masthead.jpg"></a></center> </td> <td><center><img width=440 src=" curiosity_duluth.jpg"></center> </td> <td><center> <a href=" curiosity_streambed.jpg"> <img width=400 src=" curiosity_streambed.jpg"></a></center> </td> </tr> <tr> <td> <h2><center>Sedimentary Rock</center><p><h3> A sedimenary layer one meter in thickness suggests a lake that lasted for hundreds or thousands of years. The pictured sedimentary rock are up to 75 meters in thickness. These thicker sediment deposits indicate for much longer times, tens of thousands of years (if not millions of years).<p> The lowest layer of sedimentary rock (the oldest layer) are sandstone with embedded pebbles up to nerly 1 inch across. The pebbles have varying degrees of smoothness. The pebbles are consistent with an origin in the walls of the crater dozens of kilometers away, a distance too far to have been carried by wind. They indicate a streamflow. On top of the bottom is a thicker layer of sandstone. The layer is not <i>sloped</i>, as is the lowest layer that followed the streambed. The layer is <i>flat</i> as would happen if it was deposited on the bottom of a lake. </td> <td> <h2><center>sample hole</center><p><h3> A small hole on Mars represented a big achievement for Curiosity. The hole is about 1.6 centimetres across. </td> <td> <h2><center>Streambed</center><p><h3> Analysis reveals pebble-containing slabs in an ancient streambed. The rocks are the first ever found on Mars that contain streambed gravels. The sizes and shapes of the gravels embedded in these conglomerate rocks -- from the size of sand particles to the size of golf balls -- enabled researchers to calculate the depth and speed of the water that once flowed at this location, the stream was flowing at a speed equivalent to a walking pace -- a meter per second -- and it was ankle-deep to hip-deep. </td> </tr></table></center> <p><hr><hr><p> <center><font color=green>IV. InSight</font></center> <p> <center><table border=8 cellpadding=8><tr> <td><center> <img width=680 src="insight_jpl.jpeg"><img width=800 src="InSight-dust.gif"> <img width=460 src="insight_mole.gif"></center> </td></tr> <tr><td><h2><center> <a target="_blank" href="https://mars.nasa.gov/insight/"> <font color=green>InSight:</font></a> <a href=" INSIGHT-InSight_Captures_Sound_of_a_Meteoroid_Striking_Mars_1080.mp4"> Listening to a Meteoroid</a><p> Major Results from InSight<p> </center><ul> InSight detected more than 1,300 seismic events; 50 were strong enough for study. The best data came from Cerberus Fosse, a region of recent geologic activity (within 2 million years ago). The signals lasted 6 hours with reverberations traveling through Mars several times. InSight found <p><ul> <li>the major layers of Mars, the core, mantle, and crust--the crust was thinner under InSight 25 to 40 kilometers, Mars's core was less dense, molten and larger than expected, about 1,800 kilometers in radius roughly half the size of the Earth's core. The lower density meant that Mars had lighter elements than iron mixed in with its core which is why it could be molten at lower temperatures.<p> <li>the lithosphere was thick, about 500 kilometers. On Earth, the average thickness of the lithosphere is about 100 kilometers--note that the oceanic crust is thinner than the continental crust.<p> <li>InSight found evidence that Mars had a magnetic field when younger. Currently, Mars has no magnetic field, but there is evidence in the rocks that Mars had a magnetic field just after its birth but that it disappeared after a few hundred million years. </ul><p> </ul> </td> </tr></table></center> <p><hr><hr><p> <center><font color=green>IV. NEXT STEPS</font></center> <p> <table border=8 cellpadding=8><tr> <td><img width=800 src="PIA25243.png"> <img width=800 src="PIA25326.jpg"> </td></tr> <tr><td><h2><center> <a target="_blank" href="Perseverance_Explores_Jezero_Crater_Delta.mp4"> Perseverance in Jezero crater</a> and <a target="_blank" href="https://mars.nasa.gov/msr/"> Sample Retrieval!</a></center></td> </tr></table> <p><hr><hr><p> <center> <font color=green>V. PAST SEARCHES FOR MARTIAN LIFE</font> </center> <p> <table border=8 cellpadding=8><tr> <td><img src="pia00567a.jpeg"><p><center><h2> <a href="../life/viking.html">Viking Landers: Biology Experiments</a></center></h2></td> <td><img width=880 src="alh2.gif"><p><center><h2> <a href="../life/alh84001.html">Allan Hills (ALH) 84001: Martian Meteorite</a></center></h2></td> </tr></table> <p><hr><p> <center> <a href="http://pages.uoregon.edu/~imamura/121/lecture-10/lecture-10a.html"> <img width=100 src="http://pages.uoregon.edu/~imamura/122/images/shinkansen-back.jpg"></a> <a href="http://pages.uoregon.edu/~imamura/121/lecture-12/lecture-12.html"> <img width=100 src="http://pages.uoregon.edu/~imamura/122/images/shinkansen-forward.jpg"></a> </center>