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

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.

~0.10c

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)

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 spark-discharge.

A mixture of gases (ammonia, methane, carbon dioxide, water vapor) was placed in the upper bulb

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

LfffnfRN cilep *

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 starshaving 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 bearing-

planets 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

1.2 – 2.8 A.U.

G-type star

0.85 -2.0 A.U.

End of Section