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Chapter 18
Life In The Universe
We have already launched our first robotic
spacecraft into interstellar space
Pioneers 10 and 11 carry a copy of this
etching to anyone who might find them.
Voyagers 1 & 2 carry a phonograph
record- a 12 inch gold plated
copper disk containing music,
greetings, and images from Earth
Nuclear Rocket Propulsion
~0.10c
Project Orion starship, showing one of
several small H bombs exploding. Debris
from the detonation impacts the flat disk
at the back, propelling the craft forward.
~0.10c
Project Daedalus starship. The large
spheres hold hydrogen for the central
fusion reactor.
Matter/Antimatter Rocket Engines
• Fusion converts less than 1% of the mass
of atomic nuclei into energy.
– Upper limits on speed may be ~ 0.10c.
• Matter-antimatter annihilation converts
100% of the particle mass into energy.
– Upper limits on speed may be ~ 0.90c!
Solar Sails and Beamed Energy
Spaceship propelled by a solar sail
The sail is many km across. The scientific
payload is at the central meeting point of the
four scaffold-like structures
Interstellar Ramjets
The giant scoop in front collects
interstellar hydrogen for use as fusion
fuel.
Who’s doing research along these lines?
• Scientific Research - Research Projects
Life In The
Universe
Are We Alone?
Radio Communication: Virtual Interstellar Travel
• We cannot travel at the speed of light, but
we can send and receive radio waves and
other electromagnetic waves at the speed
of light.
• In this sense, we are virtual interstellar
travelers.
The Search for Extraterrestrial intelligence
(SETI) project
• This is a project in which scientists use
large radio telescopes to search for radio
signals from other civilizations.
• SETI Institute
A 210 ft radio telescope in New South
Wales, Australia
This telescope is being
used in project
Phoenix: a project to
search nearby, Sun-like
solar systems for
signals from
extraterrestrial
intelligence.
Major Phases of Cosmic Evolution
Urey-Miller Experiment (1953 –University of Chicago)
A mixture of gases
(ammonia, methane,
carbon dioxide, water
vapor) was placed in the
upper bulb
The contents of the bulb is
believed to be representative of
the primordial Earth
atmosphere.
The mixture of gases in the bulb
were energized by a sparkdischarge.
After about one week, amino
acids and other complex
molecules were found in the
trap at the bottom. This is
representative of Earth’s
primordial oceans.
Murchison meteorite - 1969
Microscopic
sphere of
organic
matter
Contains relatively large
amounts of amino acids and
other organic material,
indicating that chemical
evolution of some sort has
occurred beyond our own
planet.
Civilizations- How many are there within our
own Milky Way Galaxy?
The answer to this question is attempted
by the Drake Equation
Frank Drake
The Drake Equation
N  R*  f p  ne  f l  f i  f c  L
N –Number of technological, intelligent
civilizations now present in the
Milky Way Galaxy
R* -rate of star formation
averaged over the lifetime
of the Galaxy
fp
- fraction of those stars
having planetary
systems
ne- average number of planets
within those planetary
systems that are suitable
for life
fl
– fraction of those habitable
planets on which life actually
arises.
fi –fraction of those life bearingplanets on which intelligence
evolves.
fc –fraction of those intelligent-life
planets that develop
technological societies.
L – average lifetime of a
technologically competent
civilization.
N ~ 1000
Habitable Zones
F-type star
G-type star
1.2 – 2.8 A.U.
0.85 -2.0 A.U.
End of Section