Mars/Martian

When considering how the evolution of life could have come about, the seeding of terrestrial life by extraterrestrial bacterial spores traveling through space (panspermia) deserves mention. Much is said about the possibility of some form of life on other planets, including Mars or more distant celestial bodies. Is it possible for some remnants of bacterial life, enclosed in a protective coat of rock dust, to have traveled enormous distances, staying dormant at the extremely low temperature of space and even surviving deadly radiation The spore may be neither alive nor completely dead, and even after billions of years it could have an infinitesimal chance to reach a planet where liquid water could restart its life. Is this science fiction or a real possibility We don t know. Around the turn of the twentieth century Svante Arrhenius (Nobel Prize in chemistry 1903) developed this theory in more detail. There was much recent excitement about claimed fossil bacterial remains in a Martian meteorite recovered from Antarctica (not since... 

How can scientists collect experimental evidence about possible life on another planet Sending astronauts to see for themselves is impractical at our current level of technology. Nevertheless, it is possible to search for life on other worlds without sending humans into space. In the late 1970s, NASA s Viking spacecraft lander collected a sample of dirt from Mars, the planet in our solar system most like Earth. The sample showed no signs of life. Nevertheless, speculation continues about Martian life. 

MIMOS II has three temperature sensors one on the electronics board and two on the SH. One temperature sensor in the SH is mounted near the internal reference absorber, and the measured temperature is associated with the reference absorber and the internal volume of the SH. The other sensor is mounted outside the SH at the contact ring assembly. It gives the approximate analysis temperature for the sample on the Martian surface. This temperature is used to route the Mossbauer data to the different temperature intervals (maximum of 13, with the temperature width software selectable) assigned in memory areas. Shown in Fig. 3.21 are the data of the three temperature sensors taken on Mars (rover Opportunity at Meridiani Planum) in January 2004 between 12 10 PM on Sol 10 (10 Martian days after landing) and 11 30 AM on Sol 11. The temperature of the electronics board inside the rover is much higher than the temperatures inside the SH and the contact plate sensor, which are nearly identical and at ambient Martian temperature. 

Fig. 3.21 Example of temperature variation as measured by MIMOS II temperature sensors on MER (i) inside the rover body at MIMOS electronics board (black curve), (ii) outside the rover, at the MIMOS II SH (green and red curves), which is at ambient Martian temperature (a) inside the sensor-head, at the reference absorber position (green), (b) outside the SH at the sample s contact plate (red). Temperatures at the two SH positions are nearly identical (difference less than 2 K). During data transmission between the rover and the Earth (or the relay satellite in Mars orbit) the instrument is switched off resulting in immediate small but noticeable temperature changes (see figure above)...

Fig. 8.34 Lefty, outcrop rocks found at the crater wall of Eagle Crater, where the rover Opportunity landed on 24 January 2004. Clearly, the sedimentary structure is seen. Right) in the spectrum, taken on sol 33 (sol = Martian day) of the mission, the mineral Jarosite, an Fe -sulfate, could be identified at the Meridiani Planum landing site. It forms only under aqueous conditions at low pH (< 3 ) and is therefore clear mineralogical evidence for aqueous processes on Mars...

Free water, the essential precondition for life as we know it, has recently been detected on Mars images taken by the high resolution stereo camera (HRSC) on board ESA s Mars Express spacecraft show a patch of water ice on the floor of an unnamed crater near the Martian north pole. Geomorphic studies indicate that the surface of Mars can be divided into two types (Jaumann et al 2002) ... 

However, the origin of the water on Mars is still unknown. Since the Earth and Mars have some common features in their history, the water on Mars could have come both from its interior and from comets and asteroids. The huge size of the Martian shield volcanoes, one class of which resembles the shield volcanoes Kilauea and Mauna Kea on Hawaii, suggests that a large proportion of the water was of volcanic origin. 

August 12, 2005, saw the launch of the US spacecraft Mars Reconnaissance Orbiter, which entered orbit around Mars on March 10, 2006. This craft has high-resolution cameras on board to permit a more exact mapping of the Martian surface (as a precondition for the search for suitable landing grounds). 

The extensive layered sediments at the south pole, which contain water ice, will provide information on climatic variations. The subsurface sounding radar instrument SHARAD (Shallow Radar) on board the Mars Reconnaissance Orbiter carried out a detailed cartographic study of the subsurface at the Martian south pole. The data indicate that the sediments there have been subjected to considerable erosion (R. Seu et al 2007). The density of the material deposited at the Martian south pole was calculated by M. T. Zuber and co-workers by combining data from the gravitational field with those from various instruments on board the Mars Orbiter, they obtained a value of 1,200 kg/m3. This value corresponds to that calculated for water ice containing about 15% dust (Zuber et al 2007). 

The layers of sediment at the Martian south pole do not consist of pure ice they are interspersed by layers of dust. The latest data were obtained by the Mars Advanced Radar for Subsurface and Ionospheric Sounding apparatus (MARSIS) on board the Mars Express Orbiter. The radar waves from the instrument pass through the ice layers until they reach the base layer, which can be at a depth of up to 3.7 km. The distribution of the ice at the south pole is asymmetric, and its total volume has been estimated to be 1.6 x 106km3 this corresponds to an amount of water which would cover the whole planet with a layer 11 metres deep (Plaut et al., 2007). 

Could it be the case that microorganisms, like the suspected fossils in the Mars meteorite ALH 84001, exist in the Martian soil This question leads to the counterquestion as to whether it has previously been possible to detect and study life (primitive life forms) under highly extreme conditions. Are there such conditions on Earth We now know quite a lot about extremophiles such as the thermophilic, halophilic and hyperthermophilic microorganisms. 

The delivery of volatiles to Earth and Mars must have been similar but where has the early Martian atmosphere gone The atmosphere of the inner planets can be seen in Table 7.3. Cometary and meteorite impacts can deliver material to a planet but are also responsible for a process called impact erosion where the atmosphere could be lost due to an impact such as the Earth-Moon capture event. Current estimates suggest that impact erosion may be responsible for the loss of 100 times the current mass of the Martian atmosphere. 

The discovery of homochirality on a planet such as Mars could be an excellent biomarker and strengthen the argument for life on Mars. With an EE in the solar nebula there should be an EE on the surface of Mars of order 9 per cent but remains of ancient life on Mars would show a greater excess. The interchange of enantiomers occurs naturally in a process called racemisation and for the most labile amino acid, aspartic acid, the half-life for the racemisation is 800 years at 300 K in 800 years, half of the non-biotic aspartic acid would racemise and the EE would go to zero. In dry conditions, however, the half-life is much longer, perhaps as large as 5 x 104 years at 300 K. Extrapolation of the racemisation rate to 215 K, the equatorial temperature of Mars, extends the half-life further to 3 x 1012 years and to 1027 years at 150 K, Martian polar temperatures. Hence, discovery of a considerable EE in the Martian soil would be a strong indicator of ancient Martian life. 

Mars rovers, Spirit and Opportunity, could deposit Earth bacteria on the Martian surface, which fortuitously could find an environment in which to colonise. One possible false alarm for Martian life exploration is that evidence is found on the Martian surface of life on Earth. Extreme measures have been taken with the NASA spacecraft to use exposure to the UV radiation from the Sun to sterilise the spacecraft, rotating the various surfaces to face a prolonged exposure, but none of this could guarantee a sterile spacecraft. 

Gibson Jr E. K. et al. (2001). Fife on Mars evaluation of the evidence within Martian meteorites ALH84001, Nakhla and Shergotty, Precabrian Research 106 15-34. 

Farquhar J, Thiemens MH (2000) The oxygen cycle of the Martian atmosphere-regoUth system secondary phases in Nakhla and Lafayette. J Geophys Res 105 11991-11998 Farquhar J, Chacko T, Ellis DJ (1996) Preservation of oxygen isotopic compositions in granuhtes from Northwestern Canada and Enderby Land, Antarctica implications for high-temperature isotopic thermometry. Contr Miner Petrol 125 213-224 Farquhar J, Thiemens MH, Jackson T (1998) Atmosphere-surface interactions on Mars mea-... 

McKay DS, et al. (1996) Search for past life on Mars possible relic biogenic activity in martian meteorite ALH 84001. Science 273 924-930... 

There are various environments in which recent formation of Fe oxides on earth can be observed. Among these are active volcanoes, soils (see Chap. 16), rivers and lakes, oceans, both hydrothermal and cold springs, and biota (see Chap. 17). All these environments supply helpful information about the pathways of Fe oxide formation in the geological past of which they may be considered as present-day analogues. Since spectroscopic information about the red Martian surface became available, there has been much speculation about the possibility of past Fe oxide formation by surface weathering on Mars. 

It is obvious from these experiments that the absorption spectrum of the Martian red surface can be simulated reasonably well by a non-unique variety of Fe rich phases or their mixtures as can the weak magnetism, so that a positive identification will probably only be possible, following further in situ analyses and/or sample return and analysis in the lab.Two Mars Exploration Rovers (MERs) are due to arrive at Mars in 2004 and will attempt to analyze rocks and soils on the surface using several small spectrometers, including PanCAM (an extended visible region spectrometer), MiniTES (a thermal emission spectrometer), APXS (alpha proton X-ray spectrometer measuring the major elements), Mossbauer (run at current local temperature), as well as a 5-level magnet array similar to that on-board the Pathfinder Lander. 

In the novel, two Martians (emigrated/immigrated) from Mars to Earth. 

Another special application of adsorption in space is presented by Grover et al. (1998). The University of Washington has designed an in situ resource utilization system to provide water to the life-support system in the laboratory module of the NASA Mars Reference Mission, a piloted mission to Mars. In this system, the Water Vapor Adsorption Reactor (WAVAR) extracts water vapor from the Martian atmosphere by adsorption in a bed of type 3A zeolite molecular1 sieve. Using ambient winds and fan power to move atmosphere, the WAVAR adsorbs the water vapor until the zeolite 3A bed is nearly saturated, and then heats the bed within a sealed chamber by microwave radiation to drive off water for collection. Tire water vapor flows to a condenser where it freezes and is later liquefied for use in tire life-support system. 

Catalysis may be of interest even on Mars. The Martian atmosphere consists of 95% carbon dioxide and Breedlove et al. (2001) have presented that nickel cluster catalysts could be used in a photoelectrochemical process to split carbon dioxide, according to the reaction... 

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