7. Martian Conditions
• Climate
– Temperature -17.2 C to -107 C
– Pressure
• 600 Pa (vs 101,000 Pa for earth)
• Lower than water triple point
• Strong thermal tides
– Wind
– Volcanic influences?
– Water
– Radiation
– Global Warming?
– Gases – 95% CO2, some methane..
Notas del editor
NASA’s Mars Science Laboratory mission is preparing to set down a large, mobile laboratory — the rover Curiosity — using precision landing technology that makes many of Mars’ most intriguing regions viable destinations for the first time. During the 23 months after landing, Curiosity will analyze dozens of samples drilled from rocks or scooped from the ground as it explores with greater range than any previous Mars rover.Curiosity will carry the most advanced payload of scientific gear ever used on Mars’ surface, a payload more than 10 times as massive as those of earlier Mars rovers. Its assignment: Investigate whether conditions have been favorable for microbial life and for preserving clues in the rocks about possible past life.There are landing parties being scheduled all over for the touchdown. See http://getcurious.com/landing-parties/. Landing time is Aug 6, 05:31 UTC which is 10:30 pm SLT. Facebook group is at https://www.facebook.com/exploremarsdotorg.
Seventeen Cameras on CuriosityThis graphic shows the locations of the cameras on NASA's Curiosity rover. The rover's mast features seven cameras: the Remote Micro Imager, part of the Chemistry and Camera suite; four black-and-white Navigation Cameras (two on the left and two on the right) and two color Mast Cameras (Mastcams). The left Mastcam has a 34-millimeter lens and the right Mastcam has a 100-millimeter lens. A suite of instruments named Sample Analysis at Mars will analyze samples of material collected and delivered by the rover’s arm. It includes a gas chromatograph, a mass spectrometer, and a tunable laser spectrometer with combined capabilities to identify a wide range of organic (carbon-containing) compounds and determine the ratios of different isotopes of key elements. An X-ray diffraction and fluorescence instrument called CheMin will also examine samples gathered by the robotic arm. It is designed to identify and quantify the minerals in rocks and soils, and to measure bulk composition. Mounted on the arm, the Mars Hand Lens Imager will take extreme close-up pictures of rocks, soil and, if present, ice, revealing details smaller than the width of a human hair. It will also be able to focus on hard-to-reach objects more than an arm’s length away. Also on the arm, the Alpha Particle X-ray Spectrometer for Mars Science Laboratory will determine the relative abundances of different elements in rocks and soils. The Mars Science Laboratory Mast Camera, mounted at about human-eye height, will image the rover’s surroundings in high-resolution stereo and color, with the capability to take and store high-definition video sequences. It will also be used for viewing materials collected or treated by the arm. An instrument named ChemCam will use laser pulses to vaporize thin layers of material from Martian rocks or soil targets up to 9 meters (30 feet) away. It will include both a spectrometer to identify the types of atoms excited by the beam, and a telescope to capture detailed images of the area illuminated by the beam. The laser and telescope sit on the rover’s mast and share with the Mast Camera the role of informing researchers’ choices about which objects in the area make the best targets for approaching to examine with other instruments. The rover’s Radiation Assessment Detector will characterize the radiation environment at the surface of Mars. This information is necessary for planning human exploration of Mars and is relevant to assessing the planet’s ability to harbor life.Curiosity Fact Sheet @ http://www.jpl.nasa.gov/news/fact_sheets/mars-science-laboratory.pdfNASA’s Mars Science Laboratory mission is preparing to set down a large, mobile laboratory — the rover Curiosity — using precision landing technology that makes many of Mars’ most intriguing regions viable destinations for the first time. During the 23 months after landing, Curiosity will analyze dozens of samples drilled from rocks or scooped from the ground as it explores with greater range than any previous Mars rover.Curiosity will carry the most advanced payload of scientific gear ever used on Mars’ surface, a payload more than 10 times as massive as those of earlier Mars rovers. Its assignment: Investigate whether conditions have been favorable for microbial life and for preserving clues in the rocks about possible past life.If a group of tourists piled out of a transport vehicle onto the surface of Mars, they'd no doubt start snapping pictures wildly. NASA's Curiosity rover, set to touch down on the Red Planet the evening of Aug. 5 PDT (early morning EDT), will take a more careful approach to capturing its first scenic views.http://www.nasa.gov/mission_pages/msl/news/msl20120803.htmlThe car-size rover's very first images will come from the one-megapixel Hazard-Avoidance cameras (Hazcams) attached to the body of the rover. Once engineers have determined that it is safe to deploy the rover's Remote Sensing Mast and its high-tech cameras, a process that may take several days, Curiosity will begin to survey its exotic surroundings."A set of low-resolution gray scale Hazcam images will be acquired within minutes of landing on the surface," said Justin Maki of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Once all of the critical systems have been checked out by the engineering team and the mast is deployed, the rover will image the landing site with higher-resolution cameras."Maki led the development of Curiosity's 12 engineering cameras -- eight Hazcams at the front and back of the rover, and four Navigation cameras (Navcams) at the top of the rover's "look-out" mast. All the engineering cameras acquire black-and-white pictures from left and right stereo "eyes," which are merged to provide three-dimensional information. Half of the cameras are backups, meaning there's one set for each of the rover’s A- and B-side redundant computers.There is one camera on the end of a robotic arm that is stowed in this graphic; it is called the Mars Hand Lens Imager (MAHLI). There are nine cameras hard-mounted to the rover: two pairs of black-and-white Hazard Avoidance Cameras in the front, another two pair mounted to the rear of the rover, (dashed arrows in the graphic) and the color Mars Descent Imager (MARDI).Credit: NASA/JPL-Caltech
This view of the head of the remote sensing mast on the Mars Science Laboratory mission's rover, Curiosity, shows seven of the 17 cameras on the rover. Two pairs of Navigation cameras (Navcams), among the rover's 12 engineering cameras, are the small circular apertures on either side of the head. On the top are the optics of the Chemistry and Camera (ChemCam) investigation, which includes a laser and a telescopic camera. The Mast Camera (MastCam) instrument includes a 100-millimeter-focal-length camera called MastCam-100 or M-100, and a 34-millimeter-focal-length camera called the MastCam-34 or M-34. The two cameras of the MastCam are both scientific and natural color imaging systems. The M-100 looks through a 1.2-inch (3-centimeter) baffle aperture, and the M-34 looks through a 2.1-inch (5.3-centimete) baffle aperture.
The Curiosity rover will be lowered by the "Space Crane" as in this picture. The Mars Science Laboratory landing sequence has been the topic of much discussion even before the mission launched on Nov. 26, 2011. Nicknamed "seven minutes of terror," the spacecraft's entry, descent and landing sequence will require a lot of things to go perfectly right — all before anyone on Earth receives even a single signal, due to the length of time it takes for information to travel from Mars to Earth.The $2.5 billion rover will begin a two-year quest to explore the interior of Mars' Gale Crater and hunt for evidence of an ancient ocean there. How crazy is this landing sequence? https://www.youtube.com/watch?v=BudlaGh1A0o&feature=player_detailpage#t=83sThe first step in this process will be a guided entry, during which the entire MSL spacecraft (currently consisting of the rover and descent stage tucked into a protective aeroshell) will adjust its course toward its 12-by-5-mile-diameter landing ellipse — only an eighth the size of the landing targets of previous rovers.As it impacts Mars' atmosphere at more than 13,000 mph, MSL's heat shield will take the brunt of the frictional heating generated by the deceleration, and will soon glow white-hot with temperatures reaching 1,600 degrees Fahrenheit (870 degrees Celsius). Even through this, MSL will still be physically guiding itself toward Gale Crater, firing rockets to keep it on track.The atmosphere on Mars, 100 times thinner than Earth's, isn't dense enough to slow MSL down by itself. So at this point a parachute will be deployed — literally the largest supersonic drogue chute ever created — to slow MSL down from 1,000 mph (1,600 kph) to about 200 mph (320 kph), subjecting the spacecraft to 9 Gs of force. (That's nine times the pull of Earth's gravity.)Then, with the surface of Mars still approaching rapidly, the spacecraft's heat shield will be jettisoned, exposing the actual rover and allowing it to use its radar guiding system to determine just how high it is. This is one of the most crucial parts of the descent, since it's not until then that MSL will be able to check its altitude."When the heat shield comes off and the radar turns on, we need to find the ground," said Sell. "When we first eject the heat shield we're too high for the radar to see the ground yet, so we have to wait a very long 20 to 30 seconds, up to a minute, until the radar can get close enough to the ground to be able to see it. Without that solution it doesn't even try to do the rest of the landing."
At nearly 2,000 pounds (900 kg), Curiosity is simply too large to land with airbags like previous rovers. Instead, engineers devised a method that's never been attempted before: a sky crane.When MSL reaches precisely the right altitude, its descent stage, gripping the Curiosity rover within the sky crane structure, will drop from the aeroshell and quickly fire its thrusters, moving it safely away from the falling back shell and slowing it further.Curiosity will be carried steadily downwards by the descent stage, which will use its Mars Descent Imager (MARDI) camera to maneuver over its target and, once at a height of 20 meters (about 65 feet) use rockets to hover in place while it lowers the rover down to the surface on bridles and an umbilical cord — all three of which are bearing the weight of the rover.
PressureThe Martian atmosphere is composed mainly of carbon dioxide and has a mean surface pressure of about 600 pascals, much lower than the Earth's 101,000 Pa. One effect of this is that Mars' atmosphere can react much more quickly to a given energy input than can our atmosphere.[21] As a consequence, Mars is subject to strong thermal tides produced by solar heating rather than a gravitational influence. These tides can be significant, being up to 10% of the total atmospheric pressure (typically about 50 Pa). Earth's atmosphere experiences similar diurnal and semidiurnal tides but their effect is less noticeable because of Earth's much greater atmospheric mass.Although the temperature on Mars can reach above freezing (0 °C), liquid water is unstable over much of the planet, as the atmospheric pressure is below water's triple point and water ice simply sublimes into water vapor. Exceptions to this are the low-lying areas of the planet, most notably in the Hellas Planitia impact basin, the largest such crater on Mars. It is so deep that the atmospheric pressure at the bottom reaches 1155 Pa, which is above the triple point, so if the temperature exceeded 0 °C liquid water could exist there.Global Warming on Mars?Evidence of recent climate change.Colaprete et al. conducted simulations with the Mars General Circulation Model which show that the local climate around the Martian south pole may currently be in an unstable period. The simulated instability is rooted in the geography of the region, leading the authors to speculate that the sublimation of the polar ice is a local phenomenon rather than a global one.[68] The researchers showed that even with a constant solar luminosity the poles were capable of jumping between states of depositing or losing ice.There have been changes around the south pole (PlanumAustrale) over the past few Martian years. In 1999 the Mars Global Surveyor photographed pits in the layer of frozen carbon dioxide at the Martian south pole. Because of their striking shape and orientation these pits have become known as swiss cheese features. In 2001 the craft photographed the same pits again and found that they had grown larger, retreating about 3 meters in one Martian year.[64] These features are caused by the sublimation of the dry ice layer, thereby exposing the inert water ice layer. More recent observations indicate that the ice at Mars' south pole is continuing to sublime.[65] The pits in the ice continue to grow by about 3 meters per Martian year. Malin states that conditions on Mars are not currently conducive to the formation of new ice.A NASA press release has suggested that this indicates a "climate change in progress"[66] on Mars. In a summary of observations with the Mars Orbiter Camera, researchers speculated that some dry ice may have been deposited between the Mariner 9 and the Mars Global Surveyor mission. Based on the current rate of loss, the deposits of today may be gone in a hundred years.[63]Elsewhere on the planet, low latitude areas have more water ice than they should have given current climatic conditions.[67] Mars Odyssey "is giving us indications of recent global climate change in Mars," said Jeffrey Plaut, project scientist for the mission at NASA's Jet Propulsion Laboratory, in non-peer reviewed published work in 2003.Despite the absence of a time series for Martian global temperatures, K. I. Abdusamatov has proposed that "parallel global warmings" observed simultaneously on Mars and on Earth can only be a consequence of the same factor: a long-time change in solar irradiance."MethaneMethane presenceMethane has been detected in the atmosphere of Mars by ESA's Mars Express probe at a level of 10 nL/L.[36][37][38] Since breakup of that much methane by ultraviolet light would only take 350 years under current Martian conditions, some sort of active source must be replenishing the gas.[39] Mars' current climate conditions may be destabilizing underground clathrate hydrates but there is at present no consensus on the source of Martian methane. In June, 2012, scientists reported that measuring the ratio of hydrogen and methane levels on Mars may help determine the likelihood of life on Mars.[40][41] According to the scientists, "...low H2/CH4 ratios (less than approximately 40) indicate that life is likely present and active."[40] Other scientists have recently reported methods of detecting hydrogen and methane in extraterrestrial atmospheres.[42][43]WindWhen the Mariner 9 probe arrived at Mars in 1971, the world expected to see crisp new pictures of surface detail. Instead they saw a near planet-wide dust storm[26] with only the giant volcano Olympus Mons showing above the haze. The storm lasted for a month, an occurrence scientists have since learned is quite common on Mars. As observed by the Viking spacecraft from the surface,[19] "during a global dust storm the diurnal temperature range narrowed sharply, from fifty degrees to only about ten degrees, and the wind speeds picked up considerably---indeed, within only an hour of the storm's arrival they had increased to 17 meters per second, with gusts up to 26 meters per second. Nevertheless, no actual transport of material was observed at either site, only a gradual brightening and loss of contrast of the surface material as dust settled onto it." On June 26, 2001, the Hubble Space Telescope spotted a dust storm brewing in Hellas Basin on Mars (pictured right). A day later the storm "exploded" and became a global event. Orbital measurements showed that this dust storm reduced the average temperature of the surface and raised the temperature of the atmosphere of Mars by 30 °C.[20] The low density of the Martian atmosphere means that winds of 40 to 50 mph (18 to 22 m/s) are needed to lift dust from the surface, but since Mars is so dry, the dust can stay in the atmosphere far longer than on Earth, where it is soon washed out by rain. The season following that dust storm had daytime temperatures 4 °C below average. This was attributed to the global covering of light-colored dust that settled out of the dust storm, temporarily increasing Mars' albedo.[27]
This is an artist's concept comparing the present day magnetic fields on Earth and Mars. Earth's magnetic field is generated by an active dynamo -- a hot core of molten metal. The magnetic field surrounds Earth and is considered global (left image). The various Martian magnetic fields do not encompass the entire planet and are local (right image). The Martian dynamo is extinct, and its magnetic fields are "fossil" remnants of its ancient, global magnetic field. "Mars has no global magnetic field comparable to Earth's geomagnetic field. Combined with a thin atmosphere, this permits a significant amount of ionizing radiation to reach the Martian surface. The Mars Odyssey spacecraft carried an instrument, the Mars Radiation Environment Experiment (MARIE), to measure the dangers to humans. MARIE found that radiation levels in orbit above Mars are 2.5 times higher than at the International Space Station. Average doses were about 22 millirads per day (220 micrograys per day or 0.08 gray per year.)[7] A three year exposure to such levels would be close to the safety limits currently adopted by NASA. Levels at the Martian surface would be somewhat lower and might vary significantly at different locations depending on altitude and local magnetic fields."Occasional solar proton events (SPEs) produce much higher doses. Some SPEs were observed by MARIE that were not seen by sensors near Earth due to the fact that SPEs are directional, making it difficult to warn astronauts on Mars early enough.Mars lost most of its magnetic field about four billion years ago. As a result, solar wind and cosmic radiation interacts directly with the Martian ionosphere. This keeps the atmosphere thinner than it would otherwise be by solar wind action constantly stripping away atoms from the outer atmospheric layer.[59] Most of the historical atmospheric loss on Mars can be traced back to this solar wind effect. Current theory posits a weakening solar wind and thus today's atmosphere stripping effects are much less than those in the past when the solar wind was stronger.[cita
Fresh Crater Revealing Buried IceRecent small craters discovered by the High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter expose buried ice in the middle latitudes of Mars. This ice is a record of past climate change. Not stable today, it was deposited during a period of different obliquity, or tilt, of the planet's axis. This image is one product from HiRISE observation ESP_011337_2360 . Other image products from this observation are available at http://hirise.lpl.arizona.edu/ESP_011337_2360. (Reference: Byrne et al., 2009)
On ancient Mars, water carved channels and transported sediments to form fans and deltas within lake basins. Examination of spectral data acquired from orbit show that some of these sediments have minerals that indicate chemical alteration by water. Here in Jezero Crater delta, sediments contain clays and carbonates. The image combines information from two instruments on NASA's Mars Reconnaissance Orbiter,the Compact Reconnaissance Imaging Spectrometer for Mars and the Context Camera. (Reference: Ehlmann et al. 2008.)
