Sigam a Água -1

FOLLOW THE LIFE

• Solvent • Biogenic elements• Source of Free Energy

searches for life within our solar system commonly retreat from a search for life to a search for “life as we know it,” meaning life based on liquid water, a suite of so-called “biogenic” elements (most famously carbon), and a usable source of free energy.

(Chyba & Hand, 2005, p. 34)

FOLLOW THE LIFE

• Follow the water• Follow the carbon• Follow the nitrogen• Follow the energy• Follow the entropy• Follow the information

Astrônomos descobrem planeta que

pode ser habitável Folha Online 24/04/2007 - 22h44

Astrônomos encontraram um planeta fora do nosso Sistema Solar que é po-tencialmente habitável, com temperaturas parecidas com as da Terra. A des-coberta foi considerada um grande passo na procura por vida extraterrestre. O planeta tem o tamanho certo, pode ter água

em forma líquida e, em termos de Universo, está relativamente perto, a cerca de 20,5 anos-luz da Terra. Ele gira em torno de uma anã vermelha --uma estrela muito menor, menos luminosa e mais fria que o nosso Sol-- chamada de Gliese 581.

O novo planeta é cinco vezes mais pesado que a Terra. Não se sabe ainda se ele é rochoso como a Terra ou se é uma esfera de gelo, com água líquida na superfície. Se for rochoso, que é o que a teoria prevalecente propõe, tem um diâmetro cerca de 1,5 vez maior que o do nosso planeta. Se for uma esfera de

gelo, seria maior ainda.

O planeta, batizado de Gliese 581c, foi descoberto pelo telescópio do Observatório Europeu do Sul (ESO) em La Silla, no Chile.Sistema planetário de Gliese

581

Instrumentos utilizados da descoberta de Gliese 581c

Telescópio de 3,6m do ESO, em La Silla, Chile, a 2400m de altitude

Equipe descobridora de Gliese 581c

Uma equipe de onze astrônomos da Suíça, França, e Portugal.

Esta equipe faz parte do grupo liderado por Michel Mayor, do Observatório de Genebra, na Suíça, responsável pela descoberta de 89 exoplanetas (até 4/6/2007)

Há 242 exoplanetas descobertos até essa data

Michel Mayor

O Estranho Sistema Solar de Gliese 581

Planeta Massa “Ano” Distância

Gliese 581b 15 MTerra 5,4 dias 6 milhões km

Gliese 581c 5 MTerra 13 dias 11 milhões km

Gliese 581d 15 MTerra 84 dias 38 milhões km

Distância “certa” para água líquida (temperatura= 0-40 C)

Gliese 581c – um mundo aquático?

Um planeta de classe Aurélia?

Um lado, dia para sempre

Outro lado, noite eterna

Por que Gliese 581c seria habitável?

R

Água Líquida !!!! Zona Habitável

A História dos Cachinhos Dourados

Nem quente demais, senão ferve

Nem frio demais, senão congela

No Sistema Solar:

Vênus sempre foi quente demais

Marte, no passado, já esteve no ponto.

A Terra em geral esteve no ponto, exceto em duas ocasiões de quase total congelamento

A própria Terra é o “Planeta Água”A própria Terra é o “Planeta Água”

A água é essencial para a vidacomo conhecemos

H2O

Água Principal componente dos

cometas e dos seres vivos

Assim, o Oxigênio e o Hidrogênio são os elementos principais de seres vivos terrestres e do Universo

Logo atrás vem o Carbono e o Nitrogênio.

DNA

H O C N + P

Relative abundances of chemical elements

Relative abundances of chemical elements (O=100)The abundances are in number (decreasing order)Sources: Lehninger 2000 (human body and Earth crust abundances); Asplind, Grevesse & Sauval 2004 (C, N, and O are

solar photospheric values; the other elements are solar system meteoritic values)

Human Body Earth Crust Cosmic

H 247 O 100 H 21 900

O 100 Si 59.6 O 100

C 37.3 Al 16.8 C 53.7

N 5.49 Fe 9.6 N 13.2

Ca 1.22 Ca 7.5 Mg 7.41

P 0.86 Na 5.3 Si 7.10

Cl 0.31 K 5.3 Fe 6.17

K 0.24 Mg 4.7 S 3.16

S 0.20 Ti 1.1 Al 0.58

Na 0.12 H 0.4 Ca 0.43

Mg 0.04 C 0.4 Na 0.41

A água também pode ser essencial para a vida em outros pontos do Universo

Afinal, há água por toda parte no Universo

H2O = Hidrogênio + Oxigênio

Hidrogênio é o elemento mais abundante do Universo e o mais simples (só um próton)

Oxigênio (seis prótons e seis nêutrons) é o segundo elemento quimicamente ativo mais abundante

Hélio (dois prótons e dois nêutrons) é o segundo elemento mais abundante mas não é quimicamente ativo

Detecting Water through the 6.2 line

Phase Diagram for Water

Triple Point273.16 K, 611.73 Pa

Critical Point647 K, 22.064 MPa

Liquid Water

• H20 is the combination of the two most abundant chemical elements in the Universe

• H20 is the most abundant tri-atomic molecule in the Universe (requires stars)

• liquid H20 is much less common (a narrow range of pressure and temperatures)

• liquid H20 requires planetary environments• highest boiling temp= 650 K (high pressures)

Water: Pros & Cons• It is easily done: it is a tri-atomic molecule and H and O

are the first and third most abundant elements in the universe.

• It remains in liquid form for a relatively large temperature range (0 – 100ºC); these limits could be extended under pressure and by the presence of dissolved salts.

• This temperature range include temperatures high enough for chemical reactions to proceed at a relatively rapid pace, but not so high that collisions destroy important, large and fragile molecules.

Water: Pros & Cons• Water is a polar solvent so that it can discriminate between polar

and non-polar molecules. Chemical discrimination results on the formation of mixed phases such as membranes, microenvironments and compartmentalization.

• Water has a very large heat of vaporization and a large heat capacity. This means that the temperatures of a solution is stabilized by the thermal properties of water as a solvent.

• Its relatively high viscosity protects living organisms from strong dynamical instabilities.

• The surface tension of water, twice that of ammonia and three times that of alcohol, exceeds the surface tension of any other liquid known.

• Its ice is less dense than that of water so that ice floats. Having a frozen ice cap protects life below the ice and prevents freezing throughout all the bulk of the liquid. (eg. EUROPA)

Water: Pros & Cons• It is rather corrosive and reactive.• It can hamper protein and nucleic acid concentrations• Its ice is less dense than that of water so that ice floats.

The high reflectivity of water ice could lead to thermal negative runaway conductive to global glaciations, that could turn into killing events.

History of the Complexity in the Universe

• 10-43 s 1. The space is born (4 extended dimensions)• 10-33 s 2. The matter is born (quarks & leptons)• 10-4 s 3. Baryons are born (quark confinements)• 1 minute 4. Nuclei are born (4He 2H 3He 7Li)• 300.000 yr 5. Atoms are born (H recombination)• 300 Myr 6. Heavy elements are born (C, O…)• 7. Heteromolecules are born (OH, CO,

H2O…)• ~10 Gyr 8. Life is born (: at least 3.5 Gyr ago)

Thermal History of the Universe

Transitions in the universe as the temperature decreases. Structures which freeze out as the universe cools include, matter, protons and neutrons, nuclei, atoms and molecules.

Transitions in the late Universe. The thin line beneath the CMB line shows how hydrogen cooled more rapidly than the CMB. The dashed line shows how this cooling would have continued if it had not been for the fact that a billion years after the big bang, the thermal energy of the hydrogen sank low enough to allow the weak gravitational binding energy to contract the densest clouds of hydrogen. These clouds then became denser and hotter and eventually formed the first stars in the universe. These massive stars emitted UV photons that heated and ionized the more rarified hydrogen (intergalactic medium : IGM). The formation of these first massive stars and the re-ionization of the IGM are represented by the vertical line at 109 years. The other lines originating at the same point represent the temperatures of hydrogen clouds that were dense enough to self-shield and avoid UV ionization. These clouds were gradually enriched with oxygen, carbon, nitrogen, iron and the other waste products of the supernovae explosions of thefirst, massive, short-lived stars. About 4.6 billion years ago one of these enriched clouds was shocked by a nearby supernova. This initiated collapse and star formation. One of the stars was the Sun. Planetary formation and formation of the Earth was part of this collapse (dotted line). Other, less dense clouds of H2 (represented by the three other thin lines) collapsed a bit but stayed at 10 or 20 K. The upper x axis shows that free energy is available once the temperature of the hydrogen is low enough to initiate gravitational collapse and star formation. Two adjacent grey strips are labeled “water”. The lower darker one is 0-100 C. The higher lighter one is 100-650 C; the highest temperatures at which water, under pressure, can exist.

Hot Ancestors and their Cool Descendants:Maximum Growth Temperatures

Phylogenetic tree of life based on 16S rRNA sequences (Pace 1997). Maximal growth temperatures have been used to color-code the branches

Re-setting the Phylogenetic Thermometer

O SISTEMA SOLARÉ ÚMIDO

SOL

MARTE

Água em Marte hoje•A baixa pressão atmosférica impede água liquída na superfície

Água líquida em Marte hoje?

• Ponto Triplo da água: (T,p)=(271.16 K, 611.73 Pa)• Pressão média em Marte: T= 600 Pa• Pressão míxima: 30 Pa (Olympus Mons)• Pressão máxima: 1150 Pa (Hellas Planitia)

Europa

Criptoendoliths

Thermophile bacteria

Hidrotermal vents

Hot geisers and volcans

ExtremófilosAntarctica

•Temperatura: -15° C < T < 230° C•0.06 < pH < 12.8•0 < Pressão < 1200 atm•Seu metabolismo pode dispensar o oxigênio•20-40 milhões de anos de dormência•2 ½ anos no espaço, a –250 C, sem

nutrientes, água and expostos a radiação

(Strep. Mitis)

Kuhn

Origem Cometária da Água na Terra?

Super Terras e Planetas-Oceano

ALTERNATIVE CHEMISTRIES

FOR LIFE?

Crovisier 2005

Evidence for chemicaldiversity Diversity among Oort cloudcomets

No systematic differencesbetween Oort cloud and

« Kuiper belt » comets

Phase transition properties of possible biosolvents

Substance Melting Point (K)

Boiling point (K)

Temperature range for liquid (K)*

Triple point temperature (K)

Triple point pressure (Pa)

Water (H2O) 273.15 373.15 100 237.16 611.73

Carbon monoxide (CO) 68 81.64 13 68.13 15400

Carbon dioxide (CO2) - - - 216.58 518500

Ammonia (NH3) 195.42 239.81 44 195.40 6076

Methane (CH4) 91. 111. 20 90.67 11690

Acetylene (C2H2) - - - 192.4 128250

Ethane (C2H6) 101. 184.6 84 91.6 1.1

Methanol (CH3OH) 176. 337.8 162 175.5 0.14

Formaldehyde (H2CO) 156.15 254.05 98 187.66 42.4

Hydrogen sulfide (H2S) 190.85 212.87 22 187.66 23200

*at 1atm pressure (101.325 kPa)

Water-based oceans

Other liquid

possibilities

OUR SOLAR SYSTEM´S LIQUID POSSIBILITIES

water/ammonia (surface lakes)

water/ammonia (subsurface)

methane/ethane

(surface lakes)

nitrogen (su

rface)

nitrogen (su

bsurface)