Exobiology in the Solar System & The Search for Life on Mars - ESA

More documents

Recommendations

Info

SP-1231 94 References Cabrol, N.A. & Gr<strong>in</strong>, E.A. (1995). A morphological view on potential niches <strong>for</strong> exobiology on Mars. Planet. Space Sci. 43, 179-188. Cabrol, N.A. et al. (1996). Ma’adim Vallis revisited through new topographical data: evidence <strong>for</strong> an ancient <strong>in</strong>travalley lake. Icarus 123, 269-283. Carr, M.H. (1987). Water on Mars. Nature 326, 30-34. Carr, M.H. (1996). Water on Mars. Ox<strong>for</strong>d Univ. Press, Ox<strong>for</strong>d, UK. Carr, M.H. & Wänke, H. (1992). Earth and Mars: Water <strong>in</strong>ventories as clues to accretional histories. Icarus 98, 61-71. Clark, B.C., Baird, A.K., Rose, Jr., H.J., Toulm<strong>in</strong>, P., Keil, K., Castro, A.J., Kelliher, W.C., Rowe, C.D. & Evans, P.H. (1976). Inorganic analyses of Martian surface samples at <strong>the</strong> Vik<strong>in</strong>g lander sites. Science 194, 1283-1288. Dreibus, G., Palme, H., Rammensee, W., Spettel, B., Weckwerth, G. & Wänke, H. (1982). Composition of Shergotty parent body: Fur<strong>the</strong>r evidence of a two component model of planet <strong>for</strong>mation. Lunar Planet. Sci. XIII, 186-187. Dreibus, G. & Wänke, H. (1984). Accretion of <strong>the</strong> Earth and <strong>the</strong> <strong>in</strong>ner planets. In Proc. 27th Intern. Geol. Con. Vol. 11, VNU Science Press, Utrecht, <strong>The</strong> Ne<strong>the</strong>rlands, pp1-20. Dreibus, G. & Wänke, H. (1987). Volatiles on Earth and Mars: A comparison. Icarus 71, 225-240. Friedman, E.I. & Ocampo, R. (1976). Endolithic blue-green algae <strong>in</strong> <strong>the</strong> dry valleys: primary producers <strong>in</strong> <strong>the</strong> Antarctic desert ecosystem. Science 193, 1247. Greeley, R. & Thomas, P.E. (Eds.) (1994). Mars Land<strong>in</strong>g Site Catalogue, NASA RP- 1238, 2nd ed. Gr<strong>in</strong>, E.A. & Cabrol, N.A. (1997). Limnological analysis of <strong>the</strong> Gusev paleolake, Mars. Icarus 130, 80-94. Karlsson, H.R., Clayton, R.N., Gibson, E.K., Mayeda, T.K. & Socki, R.A. (1991). Extraterrestrial water of possible Martian orig<strong>in</strong> <strong>in</strong> SNC meteorites: Constra<strong>in</strong>ts from oxygen isotopes. Meteoritics 26, 354-355. Kast<strong>in</strong>g, J.F. (1991). CO 2 condensation and <strong>the</strong> climate of early Mars. Icarus 94, 1-13. McKay, C.P. & Davis, W.L. (1991). Duration of liquid water habitats on early Mars. Icarus 90, 214-221. Moroz, V.I. & Mukh<strong>in</strong>, L.M. (1978). On <strong>the</strong> early stage of evolution of atmosphere and climate of <strong>the</strong> Earth’s group planets. Kosmicheskiye Issleg. 3, no.2. Pollack, J.B., Kast<strong>in</strong>g, J.F., Richardson, S.M. & Poliakoff, K. (1987). <strong>The</strong> case <strong>for</strong> a wet, warm climate on early Mars. Icarus 71, 203-204. Postawko, S.E. & Kuhn, W.R. (1986). Effect of <strong>the</strong> greenhouse gases (CO 2, H 2O, SO 2) on Martian paleoclimate. In Proc. XVI Lunar and Planet. Sci. Conf., J. Geophys. Res. 91, (B4), D431-D438. R<strong>in</strong>gwood, A.E. (1977). Composition of <strong>the</strong> core and implications <strong>for</strong> orig<strong>in</strong> of <strong>the</strong> Earth. Geochem. J. 11, 111-135. R<strong>in</strong>gwood, A.E. (1979). On <strong>the</strong> orig<strong>in</strong> of <strong>the</strong> Earth and Moon, Spr<strong>in</strong>ger Verlag, New York USA. Scott, D.H. & Chapman, M.G. (1991). Proc. 22th Lun. Plan. Sci. Conf., pp53-62. Scott, D.H. et al. (1995). US Geol. Serv. Misc. Inv. Ser., Map I-2461. Walter, M.R. & DesMarais, D.J. (1993). Preservation of biological <strong>in</strong><strong>for</strong>mation <strong>in</strong> <strong>the</strong>rmal spr<strong>in</strong>g deposits: develop<strong>in</strong>g a strategy <strong>for</strong> <strong>the</strong> search <strong>for</strong> fossil life on Mars. Icarus 101, 129-143. Wänke, H. (1981). Constitution of terrestrial planets. Phil. Trans. R. Soc., Lond., A, 303, 287-302. Wänke, H. & Dreibus, G. (1994). Chemistry and accretion history of Mars. Phil. Trans. R. Soc. Lond. A, 349, 285-293. Watson, L.L., Epste<strong>in</strong>, S. & Stolper, E.M. (1991). Hydrogen and carbon isotopic composition of volatiles <strong>in</strong> Nakhla: Implications <strong>for</strong> wea<strong>the</strong>r<strong>in</strong>g on Mars. In Workshop on <strong>the</strong> Martian surface and atmosphere through time, Lunar and Planetary Institute, Houston, USA, LPI Tech. Report No. 92-02, pp165-166.
II.3 <strong>The</strong> Martian Meteorites ‘When two great masses come <strong>in</strong>to collision <strong>in</strong> space it is certa<strong>in</strong> that a large part of each is melted; but it seems also quite certa<strong>in</strong> that <strong>in</strong> many cases a large quantity of debris must be shot <strong>for</strong>th <strong>in</strong> all directions; much of which may have experienced no greater violence than <strong>in</strong>dividual pieces of rock experience <strong>in</strong> a land slip or <strong>in</strong> blast<strong>in</strong>g by gunpowder.’ Lord Kelv<strong>in</strong>, address<strong>in</strong>g <strong>the</strong> British Association <strong>in</strong> 1871 Our <strong>in</strong>terest <strong>in</strong> meteorites here is two-fold. Firstly, as mentioned <strong>in</strong> Section I.2, <strong>the</strong>y provided <strong>the</strong> early Earth with substantial amounts of carbon <strong>in</strong> <strong>in</strong>organic and organic <strong>for</strong>ms. Secondly, <strong>the</strong>y can provide <strong>in</strong><strong>for</strong>mation on <strong>the</strong> constitution and conditions of <strong>the</strong>ir orig<strong>in</strong>al parent bodies. Of especial <strong>in</strong>terest here are those few meteorite samples that appear to have orig<strong>in</strong>ated from Mars. Indeed, one of <strong>the</strong> reasons that exobiology is excit<strong>in</strong>g much debate is <strong>the</strong> announcement concern<strong>in</strong>g <strong>the</strong> possibility of biological fossils <strong>in</strong> martian meteorite ALH 84001 (hereafter referred to as A84) (McKay et al., 1996). <strong>The</strong> obvious implication of this observation, if <strong>the</strong>y are biological fossils, is that <strong>the</strong>re was once life on Mars. Actually witness<strong>in</strong>g <strong>the</strong> fall of a meteorite is a rare event; only 5-8 are reported each year. O<strong>the</strong>r than that, a few meteorites are found simply ly<strong>in</strong>g on <strong>the</strong> ground. This all adds up to a museum-based meteorite collection around <strong>the</strong> world of about 2500 specimens. In addition, <strong>the</strong>re are <strong>the</strong> meteorites collected by dedicated expeditions to Antarctica and o<strong>the</strong>r deserts, by <strong>the</strong> US, Japan, Australia and Europe. <strong>The</strong>se may return with 200-1000 fragments per year, but often <strong>the</strong>re may be many separate pieces of a s<strong>in</strong>gle meteorite. Clearly, <strong>the</strong>re<strong>for</strong>e, it is difficult to estimate <strong>the</strong> total number of meteorites retrieved by <strong>the</strong> collection trips. A best guess of <strong>the</strong> total number ever collected (i.e. museum-based and by systematic searches) is somewhere <strong>in</strong> <strong>the</strong> region of 5000-8000. Most meteorites orig<strong>in</strong>ate from bodies <strong>in</strong> <strong>the</strong> asteroid belt. Some can even be tracked to a specific asteroid, Vesta. <strong>The</strong>re are a fur<strong>the</strong>r 18 samples from <strong>the</strong> Moon. In addition, <strong>the</strong>re are currently 12 o<strong>the</strong>rs that are lumped toge<strong>the</strong>r on <strong>the</strong> basis of a number of common characteristics (some of which make <strong>the</strong> samples quite clearly dist<strong>in</strong>ct from asteroidal debris). Orig<strong>in</strong>ally, <strong>the</strong>se were called <strong>the</strong> ‘SNC meteorites’, on account of <strong>the</strong>re be<strong>in</strong>g three subgroups that had been recognised historically (<strong>the</strong> Shergottites, Nakhlites and Chassignites). II.3.1 Introduction Fig. II.3.1/1. Martian meteorite ALH 84001, derived from a lava flow 4.5 Gyr ago. It was ejected from Mars about 16 million years ago and entered <strong>the</strong> Earth’s atmosphere some 13 000 years ago, land<strong>in</strong>g <strong>in</strong> Antarctica. (NASA Johnson Space Center) 95
Page 1 and 2:
SP-1231 Exobiology
Page 3 and 4:
Cover Fossil coccoid bacteria, 1 µ
Page 5 and 6:
4 I.5 Potential Non-Martian Sites <
Page 7 and 8:
6 6.2 Imaging of F
Page 9 and 10:
The Exobio
Page 11 and 12:
pyrolysis, or similar techniques, f
Page 13 and 14:
Ignasi Casanova, Institute
Page 15 and 16:
I AN EXOBIOLOGICAL VIEW OF THE SOLA
Page 17 and 18:
SP-1231 18 surface pressure of CO 2
Page 19 and 20:
SP-1231 20 10 bar befor</st
Page 21 and 22:
SP-1231 22 kilometres in</s
Page 23 and 24:
SP-1231 24 Laboratory Investigation
Page 25 and 26:
I.3 Limits of Life
Page 27 and 28:
temperatures of 95-106ºC. This sug
Page 29 and 30:
(mainly found <str
Page 31 and 32:
cannot exclude fin
Page 33 and 34:
Responses to Cosmic Radiation <stro
Page 35 and 36:
acid to identify the</stron
Page 37 and 38:
Horneck, G. (1993). Responses of Ba
Page 39 and 40: SP-1231 Fig. I.4.2.2/1. Size distri
Page 41 and 42: SP-1231 Fig. I.4.2.2/4. Evaporite w
Page 43 and 44: SP-1231 Fig. I.4.2.3/1A (left). Net
Page 45 and 46: SP-1231 48 A detailed chemical anal
Page 47 and 48: SP-1231 Fig. I.4.3.1.1/1. Scheme of
Page 49 and 50: SP-1231 Fig. I.4.3.1.2/1. A: Compar
Page 51 and 52: SP-1231 54 I.4.3.2.1 Sedimentary Or
Page 53 and 54: SP-1231 56 The iso
Page 55 and 56: SP-1231 Fig. I.4.3.2.3/1. Cholester
Page 57 and 58: SP-1231 60 References regard to non
Page 59 and 60: SP-1231 62 Klein,
Page 61 and 62: SP-1231 64 ities in</strong
Page 63 and 64: SP-1231 Fig. I.5.1.1/1. A 34×42 km
Page 65 and 66: SP-1231 Fig. I.5.2.1/1. Titan’s a
Page 67 and 68: SP-1231 Fig. I.5.2.2/2. Modelled Ti
Page 69 and 70: SP-1231 72 Galileo: images availabl
Page 71 and 72: SP-1231 74 TABLE I.6.2/1 EVIDENCE O
Page 73 and 74: SP-1231 I.6.3 What to Searc
Page 75 and 76: SP-1231 78 I.7.3 Organic Chemistry
Page 77 and 78: II.1 Introduction The</stro
Page 79 and 80: II.2 The Planet Ma
Page 81 and 82: cover the range 4.
Page 83 and 84: The depletion of c
Page 85 and 86: valley networks (Fig. II.2.5/2) are
Page 87 and 88: plate tectonic evidence has been ob
Page 89: Table II.2.7.4/1. Potential Mars <s
Page 93 and 94: principal atmosphe
Page 95 and 96: Lines of evidence
Page 97 and 98: indicated by carbo
Page 99 and 100: quest for
Page 101 and 102: Anders, E. (1989). Prebiotic organi
Page 103 and 104: Urey, H.C. (1968). Origin</
Page 105 and 106: SP-1231 Fig. II.4.1.1/1. A Gilbert-
Page 107 and 108: SP-1231 Fig. II.4.1.3/1. Th
Page 109 and 110: SP-1231 114 Sinuou
Page 111 and 112: SP-1231 Fig. II.4.3/1. Ages of seve
Page 113 and 114: SP-1231 118 orbital characteristics
Page 115 and 116: SP-1231 120 II.4.5 The</str
Page 117 and 118: SP-1231 122 II.4.6 Rovers and Drill
Page 119 and 120: SP-1231 124 Site 2: Apolin<
Page 121 and 122: SP-1231 126 Site 4: Chasma area, ea
Page 123 and 124: SP-1231 128 Sharp, M., Parkes, J.,
Page 125 and 126: SP-1231 Fig. II.5.1/1. The<
Page 127 and 128: SP-1231 132 II.5.3 Isotopic Analysi
Page 129 and 130: SP-1231 134 chemical composition de
Page 131 and 132: SP-1231 Fig. II.5.7.1/1. Th
Page 133 and 134: SP-1231 138 optical microscope. Bot
Page 135 and 136: SP-1231 140 protons of discrete ene
Page 137 and 138: SP-1231 142 atures should be per<st
Page 139 and 140: SP-1231 Fig. II.5.7.7/1. Example of
Page 141 and 142:
SP-1231 146 soils. In this approach
Page 143 and 144:
SP-1231 148 discrimin</stro
Page 145 and 146:
SP-1231 150 determin</stron
Page 147 and 148:
SP-1231 Fig. II.5.10.2/2. Enantiome
Page 149 and 150:
SP-1231 154 References achiral colu
Page 151 and 152:
II.6 Team III: The
Page 153 and 154:
in width and heigh
Page 155 and 156:
Searchin</
Page 157 and 158:
minerals or oxidat
Page 159 and 160:
A second group of rocks, however, m
Page 161 and 162:
SCIENTIFIC METHOD AND REQUIREMENTS
Page 163 and 164:
The sample materia
Page 165 and 166:
surprising. To ach
Page 167 and 168:
The main</
Page 169 and 170:
Consideration of a diamond wire-saw
Page 171 and 172:
Schoonen, M.A. & Barnes, H.L. (1991
Page 173 and 174:
SP-1231 180 II.7.2 The</str
Page 175 and 176:
SP-1231 Fig. II.7.4/1. Look
Page 177 and 178:
SP-1231 184 II.7.5 A Possible <stro
Page 179 and 180:
Team IV was asked to examin
show all

Exobiology in the Solar System & The Search for Life on Mars - ESA

Create successful ePaper yourself

Delete template?

Save as template?