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2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 WHY BEING EARTH-CENTERED WHEN SEARCHING FOR LIFE IN THE COSMIC NEIGHBORHOOD? Carlos Alexandre Wuensche1 Claudia Lage2 Amâncio Friaça3 Sérgio Pilling4 Heloísa Boechat-Roberty5 1Divisão de Astrofísica, - INPE 2Instituto de Biofísica Carlos Chagas Filho - UFRJ 3Instituto Astronômico e Geofísico - IAG/USP 4Instituto de Química - UFRJ 5Observatório do Valongo - UFRJ Contato: [email protected] 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 A cosmological perspective to search of life in the Universe... Bennett et al., ApJ Suppl Series 2003 Ωb = 0.04 ΩT LET´S GIVE IT UP, THEN... NOT! Life building blocks come from these components... 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 How can we define life? • It is quite a subjective concept, but we can list some common characteristics (J. Schneider, astroph/9604131, 1996; Szostak et al., Nature, 2001, Bains, Astrobiology 2005) – Complex and diversified interactions with the environment – System out of thermodynamical equilibrium – Memory + reading/recovering mechanism – Self-replication capability Life is a self-sustained chemical system, capable of evolution in a Darwinian sense (Joyce 1994). 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 For a practical search, restrictive hipothesis... • What kind of complex systems? – Liquid crystals, plasmas... • Conservative hipothesis – a chemical system. – C, Si? • Presence of a liquid millieu? – H2O: excelent solvant and abundant in the Universe • Existence of a solid/liquid interface? – Favours molecular interactions... Questions 1) Does life need, necessarily, such atoms and physical-chemical conditions? 2) Can life develop, in another planet, under totally different conditions? 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 Most definitions tend to be EARTH-CENTERED So, let´s understand “Earth model” 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 Lineweaver et al., Science, 303, 59 (2004) 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 HABITABLE ZONE (68% e 95%) 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 Biologically interesting elements abundance in the Galaxy •[X/H]=log(X/H)-log(X/H)Sun. •Components: halo, thick and thin disks. •Universe age: 13 Gyr. •Solar age: 4.6 Gyr Minimum abundance to form terrestrial planets: [X/H]=-1.0 +/- 0.3. (Lineweaver, Icarus, 151, 307, 2001) 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 Stellar habitable zone Main assumptions: Surface H2O for ~ Gyear, geological activity, CO2-H2O-N2 atmosphere, B-field, climate stability, resistance to catastrophes for ~ Gyear R 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 In the early Earth: Miller & Urey, 1961 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 Pre-cellular life... Where does it come from? • Nucleic acids required! • But NO NUCLEIC ACIDS were found in Miller & Urey experiment. • How could they be formed? Polymerisation of cyanide, which can be readily formed in a primitive atmosphere! • So what? This still doesn't look much like a nucleic acid! However, the tetramer can be rearranged as follows: Images´ source: http://www.whfreeman.com/life/update/ Saladino et al., Chem. Biochem, 2004 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 Pathways for biomolecule formation in space: the glycine case - Environment ORION M42 Young stars T ~ 30000K X-rays 1 Ori C Lx ~ 2 x1032 erg s-1 (Chandra) ne ~ 5000 neMI Excitation of rotationalvibrational levels TRAPEZIUM - HST 2003 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 Pathways for biomolecule formation in space: the glycine case - Model PDRs Typical Features FUV ~ 10-100 erg cm-2 s-1 ngas ~ 104-105 cm-3 (107-103 cm-3) T ~ 50-200 K (10 - 1000 K) Tielens & Hollenbach (1985) ApJ 291, 747 Schulz etal 2001 ApJ, 549, 4441 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 Measurements in space Methylenimine NH2CH2COOH Acetic acid + (-H2O; -H) + (-H2) Formic acid + Ammonia Which pathway is more probable? Formation via ice or gas phase? + + (-H2O; -H) (-H2O) methanolamine Protonated Hidroxilamine Protonated methanolamine Formic acid ice/gas ratio ~ 10000! Ehrenfreund et al 2001 JGR , 106, E12, 33291; Whittet et al 1996 A&A 315, L357 Low resistence to radiation field? 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 Results from space Through acetic acid (~6x 1015 cm2) (~2 x 1015 cm2) Kuan etal 2004 ASR, 33, 31 Remijan etal 2002 ApJ 576, 264 Through formic acid Liu etal 2002 Apj 576, 255 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 Results from collisions at LNLS 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 Recent detection of a PANH in the IR Hudgins et al. ApJ, 2005 H N C Caffeine • Spitzer detected PANHs in various galaxies, besides our own. • First direct evidence for the presence of a prebiotic interesting compound in space. • Presence of N is essential in biologically interesting compounds (clorophyle). • The presence of a planet is no longer necessary for the formation of a PANH. 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 Astrobiologically interesting stars and planets Porto de Mello et al., Astrobiology, 2005 Thermal IR CO2 15 m O3 9.6 m H2O: 6.3 m + 12 m band to microwaves CH4 7.7 m Window at 8-12 m: surface temperature Color temperature + flux = radius (problems with clouds) Explore the star/planet contrast in the thermal IR (Des Marais et al 2002, Segura et al 2003) 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 Any alternatives at this point??? • Other liquids may define other biochemistries • Ammonia (Jupiter satellites), methane/ethane (Titan), nitrogen (silicon-oriented) • Light (mostly IR) on the surface of Titan may allow photosynthesis-like processes, even at low temperatures. • Chemolitotrophy possibly available in any liquid environment (Galilean satellites). 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 OUR SOLAR SYSTEM´S LIQUID POSSIBILITIES Water-based oceans Other liquid possibilities 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 Extremophiles survival chart Hidrotermal vents • • • • • • Temperature: -15° C < T < 230° C 0 < pH < 12 0 < Pressure < 1200 atm No mandatory oxygen-based metabolism 20-40 Myears of dormancy 2 ½ years in space, at 20 K, with no nutrients, water and exposed to radiation Antarctica (Strep. Mitis) Criptoendoliths Hot geisers and volcans Thermophile bacteria 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 What do we suggest? • Carbon based, DNA-like search, in planetary systems – Targeting small constituints of organic compounds – IR/X (Pilling et al., A&A 2005) – Targeting PANHs – IR (Hodges et al., ApJ 2005) • Other alternatives (chemical/physical) – Other liquids/fluids demand a different chemistry (not CHON based) due to thermodynamical requirements (Bains, Astrobiology 2005). – Self-sustained ability to disturb a local environment (Bains, Astrobiology 2005). 2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005 WHERE IS DNA OR ANY OF ITS RELATIVES? The end… … or the beginning?????