1. The Search for Life in the Solar System
HNRS 228 w/Geller
Spring 2005
Reviewing Chapter 6

2. What’s Up Review Requirements for Life
Elements, Energy, Water, etc.
Searching for Life in Our Solar System
Remote Sensing, Robotics, Human Exploration, etc.
Biological Tour of the Solar System
Terrestrial Planets, Jovian Planets, other bodies

3. Source of elements to build cells Source of energy
Environment for Life?
Source of elements to build cells
Source of energy
Medium for transporting molecules

4. H2O and CO2 Phase Diagrams (IMPORTANT environmental consideration)

5. Exploring the Solar System
Observations from Earth
ground or orbit based
Robotic spacecraft
flybys, orbitals
landers
Human exploration

6. Planet Generalization
Terrestrial planets are closer to sun
Mercury
Venus
Earth
Mars
Jovian planets furthest from sun
Jupiter
Saturn
Uranus
Neptune

7. Planetary Summary

8. Some Conclusions Planets formed at same time as sun
Planetary and satellite/ring systems are similar to remnants of dusty disks such as that seen about stars being born (e.g. T Tauri stars)
Planet composition dependent upon where it formed in solar system

9. Nebular Condensation Model
Most remnant heat from collapse retained near center
After sun ignites, remaining dust reaches an equilibrium temperature
Different densities of the planets are explained by condensation temperatures
Nebular dust temperature increases to center of nebula

10. Nebular Condensation Physics
Energy absorbed per unit area from sun = energy emitted as thermal radiator
Solar Flux = Lum (Sun) / 4 x distance2
Flux emitted = constant x T4 [Stefan-Boltzmann]
Concluding from above yields
T = constant / distance0.5

11. Nebular Condensation Chemistry

12. Nebular Condensation Summary
Solid Particles collide, stick together, sink toward center
Terrestrials -> rocky
Jovians -> rocky core + ices + light gases
Coolest, most massive collect H and He
More collisions -> heating and differentiating of interior
Remnants flushed by solar wind
Evolution of atmospheres

13. Biological Tour of the Solar System
Consider problems posed for life on each of the following
Moon
Mercury
Venus
(Mars will be discussed in Chapter 7)
Jovian Planets
Other Moons
Asteroid, comets and other debris

14. Some References The Search for Life (especially in the solar system)
Books
Life on Other Worlds (Dick)
Cradle of Life (Schopf)
Life Everywhere (Darling)
Life on Other Worlds and How to Find It (Clark)