Aula 8
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)
Six “Major Biogenic Elements”:
Carbon, Hydrogen, Oxygen, Nytrogen, Sulfur,
Phosphorous (CHON + S + P)
Five “Minor Biogenic Elements”:
Sodium, Potassium, Magnesium, Calcium, Chlorine
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 potencialmente 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.
Sistema planetário de Gliese 581
O planeta, batizado de Gliese 581c, foi descoberto
pelo telescópio do Observatório Europeu do Sul
(ESO) em La Silla, no Chile.
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.
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
Michel Mayor
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 mais de 680 exoplanetas descobertos
até hoje
Detection of PlanetsRadial Velocity Method
Detection of PlanetsTransit Method
130,000 observed stars, ~150 new telluric
Blue Moon em torno de um Jupiter Quente
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
Por que Gliese 581c seria habitável?
Água Líquida !  Zona Habitável
R
A própria Terra é um “Planeta Água”
Europa – Um Oceano
Subterrâneo
18
19
NUPESC Ago 2012
19
A água é essencial para a vida
como conhecemos
H2 O
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
Água
Principal componente dos
cometas e dos seres vivos
Assim, o Oxigênio e o
Hidrogênio são os elementos
principais do Universo e dos
seres vivos terrestres
Logo atrás vem o Carbono e
o Nitrogênio.
DNA
HOCN+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
Na 5.3
Si 7.10
Cl 0.31
K
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
0.86
5.3
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 (but, requires stars to form O)
liquid H20 is much less common (needs a
narrow range of pressure and temperatures)
liquid H20 requires planetary environments
highest boiling temp= 650 K (high pressures)
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.
COSMIC BLACK BODY RADIATION
(“3 degree K Radiation”)
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
Detecting Water in the Universe through the 6.2 line
HAC = Hydrogenated Amorphous Carbons
Water: Pros & Cons
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

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 of vaporization. This means that the temperatures of
in solution is stabilized by the thermal properties of water
as a solvent.
Its relatively high viscosity protects living organisms from
strong dynamical instabilities.
Water: Pros & Cons
• 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)
• 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.
Water: Pros & Cons
• 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)
• 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.
Phase Diagram for Water
Critical Point
647 K, 22.064
MPa
Triple Point
273.16 K, 611.73 Pa
ALTERNATIVE CHEMISTRIES
FOR LIFE?
Melting and boiling point of possible
solvents for life
Solvent
Melting Point (o C)
Boiling point (o C)
Temperature
for liquid*
H2O
0
100
100
NH3
-78
-33
45
CH4
-182
-164
18
C 2H 2
-183
-89
94
CH3OH
-94
65
155
range
OUR SOLAR SYSTEM´S
LIQUID POSSIBILITIES
Water-based oceans
Other liquid
possibilities
O SISTEMA SOLAR
É ÚMIDO
SOL
MARTE
Água em Marte hoje
•A baixa pressão atmosférica impede água liquída na
superfície
Water on Mars
Water on Mars
Water on Mars
Water droplets collected on NASA’s Phoenix
lander
Água líquida em Marte hoje?
•
•
•
•
Ponto Triplo da água: (T,p)=(271.16 K, 611.73 Pa)
Pressão média em Marte: T= 600 Pa~6 mili atm
Pressão míxima: 30 Pa (Olympus Mons)
Pressão máxima: 1150 Pa (Hellas Planitia)
Mars
Europa (lua de Jupiter)
Extremófilos
Antarctica
Hidrotermal
vents
• 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)
Criptoendoliths
Hot geisers and volcans
Thermophile bacteria
Kuhn
Origem Cometária da Água na Terra
Comets, Astronomy & Astrobiology



•
Comets are the key to
understanding the Solar
Nebula & its evolution.
Comets could serve as
probes of chemical
processes occurring in the
midplanes of astronomical
disks
Comets may have
provided key organic
nutrients required to jump
start life on Earth.
When comets are near the Sun and active, comets
have several distinct parts:
 nucleus: relatively solid and stable, mostly ice and gas
with a small amount of dust and other solids
coma: dense cloud of water, carbon dioxide and other
neutral gases sublimed from the nucleus
hydrogen cloud: huge (millions of km in diameter) but
very sparse envelope of neutral hydrogen
dust tail: up to 10 million km long composed of smokesized dust particles driven off the nucleus by escaping
gases; this is the most prominent part of a comet to the
unaided eye
ion tail: as much as several hundred million km long
Major Comet Structures
HI CLOUD
ION TAIL
NUCLEUS
COMA
THE COMA
Molecules are liberated from the nucleus
by solar heating and sublimation
Molecules are destroyed by photodissociation &
photoionization
H2O + h
OH + h
H + OH
H+O
H2O + h
H2O+ + e-
Nucleus molecules are referred to as the “parent
molecules”
The fragments produced by the absorption of a photon
are called “daughters”
Chemical Composition of Comets
(The grey bar indicates the range measured to date)
Abundances (%, relative to water)
Bockelee-Morvan, Crovisier, Mumma, and Weaver (Comets II, 2003)