Overview The course takes an investigative approach, using basic physics to explain a wide variety of phenomena on Earth. From Space:- Week 1 (1) A survey of the planets of the solar system suggests that only plausible candidates to be Earth, Mars and Venus. The star is quite average, in the middle of its lifespan, and with a stable output allowing equable conditions to persist for long enough for development of life. (2) Earth has a strong magnetic field and an atmosphere that together shield the surface of the planet from high radiation. Internal origin of the magnetic field probably implies a metallic liquid core and a dynamic planet. Physical principles emphasized: States of matter, forces, motion of charged particles in electrical fields. Week 2 (3) Magnetic fields continued… (4) Remote sensing. There is atmosphere with oxygen. The vertical structure of temperature and the distribution and motion of water vapor clouds demonstrate that rotational effects and phase changes dominate the physics of the atmosphere and that biological activity is almost certainly high. (5) Three fourths of the surface is covered by liquid water. Its enormous thermal capacity has the potential to make climate stable. Physical principles emphasized: Blackbody radiation, energy balance, remote sensing by absorption spectroscopy Lab 2: Radiation, planetary energy balance Week 3 (6) The land is mostly flat and very close to sea level. Because there are very few meteor craters compared to Earth’s moon, one can conclude that erosion very effectively removes topographic structure. (7) Mountains are in linear belts. The presence of ice and high precipitation associated with these topographic features also implies high erosion and requires that high topography be maintained by some dynamical process. (8) Surface rocks on land are high in silica, while those on ocean islands are commonly much lower in silica. The density of all surface rocks is much less than the average density of the planet lending further credence to an active planet with ongoing chemical differentiation. Physical principles emphasized: Potential energy, stream power in rivers, diffusion, erosion II. Before landing:- Week 4 (9) The oceans are strongly stratified in the near surface. This requires large-scale vertical circulation of oceanic scale and allows the entire depth of the ocean to play a role in climate. (10) Strong, warm surface currents flow away from the equator on the west side of all ocean basins. This poleward transport of heat has a dominant effect on climate. It keeps most of the ocean ice-free and makes much more of the land surface habitable than would otherwise be the case. Physical principles emphasized: Diffusion, diffusion, diffusion, Rotation, Fluid motion, Coriolis force Week 5 (11) Heating of the atmosphere near the equator drives air upward. Ice and Cooling near the poles causes air to sink. This large-scale atmospheric circulation, coupled with coriolis effects results in a dominant west to east motion of weather systems at mid-latitudes. Physical principles emphasized: Fluid motion (contd.), atmospheric circulations, and thermodynamics Week 6, (12) Weather systems are significantly modified by distribution of land and sea and topography, and are organized into storm tracks by the presence of the atmospheric jets. This makes some surface areas highly desirable and others nearly un-inhabitable. (13) Some areas experience dramatic seasonal variations in climate, caused by the shifting patterns of the circulation, which causes dramatic variations in the ecosystem. Physical principles emphasized: Fluid motion (contd.), atmospheric circulations, and thermodynamics. Week 7, (14) The ocean basins are covered with linear magnetic anomalies, while the continents are not. (15) The gravity field implies that most high topography is locally compensated. This is more evidence for internal deformation. (16) The ocean basins are not of uniform depth, but have median ridges and locally linear deep trenches. Sampling of the ridges finds young volcanic rocks. III. On the surface:- (17) An array of seismometers demonstrates that seismic activity is not randomly located, but is generally located in linear bands. It is mostly confined to depths less than 30 km and is common near the crest of ocean ridges. However, in the linear bands that coincide with the deep ocean trenches, seismicity occurs in zones that dip into the interior to depths up to 600 km. These zones are always coincident with volcanic activity. Some seismic events are very large and would pose a hazard to developed infrastructure. (18) Analyses of seismic waves that travel great distances in the interior demonstrate that Earth is, to first order, radially symmetric and confirms that it has a liquid core with an inner solid core, a nearly uniform mantle and a crust that is much thinner in the ocean basins than on the continents. Physical principles emphasized: Waves, group velocity and phase speed, Shear and compression waves, Seismic ray propagation, tectonic structure. Week 9, November 22nd (Thanksgiving, Thursday, Friday) (19) The linear ocean magnetic anomalies are commonly symmetric about ocean ridge crests and have very similar spatial patterns for different ridges. This suggests a common origin for all anomalies. A time sequence of reversals of Earths geodynamo is suggested and successfully tested by the natural remnant magnetism in rocks and sedimentary cores. This proves that the ocean ridges are spreading. Most seismic activity is then easily reconciled with large-scale convective motion with downwelling associated with the deep events. (20) Continents are then recognized as the product of differentiation during this process that produces material too light to return to the interior. Continental collision is the remaining major influence on surface structure. (21) A spectrum of geophysical techniques are used to evaluate natural resource potential of the planet. Physical principles emphasized: Geodynamics, Tectonic structure, dating techniques Week 10 (22) Years of surveying show the existence of hurricanes, tornados, winter storms, fires, droughts. Some areas are more vulnerable than others. Surface surveys show the importance of temperate climate for nutrient production and sustainable agriculture (23) Ice core studies are used to determine the climate history and its relation to the demise of the earlier civilization Physical principles emphasized: Feedbacks, uncertainty Week 11 (24) A review meeting is held to synthesize available information pertinent to the viability of a colony. (25) Avoiding the problems that led to the demise of Earth’s former occupants and quantifying other potential difficulties is the main topic. (26) Bring it all together and dealing with inevitable overflow. Physical principles emphasized: Everything!

Overview

The course takes an investigative approach, using basic physics to explain a wide variety of phenomena on Earth.

From Space:-

Week 1

(1) A survey of the planets of the solar system suggests that only plausible candidates to be Earth, Mars and Venus. The star is quite average, in the middle of its lifespan, and with a stable output allowing equable conditions to persist for long enough for development of life.

(2) Earth has a strong magnetic field and an atmosphere that together shield the surface of the planet from high radiation. Internal origin of the magnetic field probably implies a metallic liquid core and a dynamic planet.

Physical principles emphasized: States of matter, forces, motion of charged particles in electrical fields.

Week 2

(3)Magnetic fields continued…

(4)Remote sensing. There is atmosphere with oxygen. The vertical structure of temperature and the distribution and motion of water vapor clouds demonstrate that rotational effects and phase changes dominate the physics of the atmosphere and that biological activity is almost certainly high.

(5)Three fourths of the surface is covered by liquid water. Its enormous thermal capacity has the potential to make climate stable.

Physical principles emphasized: Blackbody radiation, energy balance, remote sensing by absorption spectroscopy

Lab 2: Radiation, planetary energy balance

Week 3

(6)The land is mostly flat and very close to sea level. Because there are very few meteor craters compared to Earth’s moon, one can conclude that erosion very effectively removes topographic structure.

(7)Mountains are in linear belts. The presence of ice and high precipitation associated with these topographic features also implies high erosion and requires that high topography be maintained by some dynamical process.

(8)Surface rocks on land are high in silica, while those on ocean islands are commonly much lower in silica. The density of all surface rocks is much less than the average density of the planet lending further credence to an active planet with ongoing chemical differentiation.

Physical principles emphasized: Potential energy, stream power in rivers, diffusion, erosion

II. Before landing:-

Week 4

(9)The oceans are strongly stratified in the near surface. This requires large-scale vertical circulation of oceanic scale and allows the entire depth of the ocean to play a role in climate.

(10) Strong, warm surface currents flow away from the equator on the west side of all ocean basins. This poleward transport of heat has a dominant effect on climate. It keeps most of the ocean ice-free and makes much more of the land surface habitable than would otherwise be the case.

Physical principles emphasized: Diffusion, diffusion, diffusion, Rotation, Fluid motion, Coriolis force

Week 5

(11) Heating of the atmosphere near the equator drives air upward. Ice and Cooling near the poles causes air to sink. This large-scale atmospheric circulation, coupled with coriolis effects results in a dominant west to east motion of weather systems at mid-latitudes.

Physical principles emphasized: Fluid motion (contd.), atmospheric circulations, and thermodynamics

Week 6,

(12) Weather systems are significantly modified by distribution of land and sea and topography, and are organized into storm tracks by the presence of the atmospheric jets. This makes some surface areas highly desirable and others nearly un-inhabitable.

(13) Some areas experience dramatic seasonal variations in climate, caused by the shifting patterns of the circulation, which causes dramatic variations in the ecosystem.

Physical principles emphasized: Fluid motion (contd.), atmospheric circulations, and thermodynamics.

Week 7,

(14) The ocean basins are covered with linear magnetic anomalies, while the continents are not.

(15) The gravity field implies that most high topography is locally compensated. This is more evidence for internal deformation.

(16) The ocean basins are not of uniform depth, but have median ridges and locally linear deep trenches. Sampling of the ridges finds young volcanic rocks.

III. On the surface:-

(17) An array of seismometers demonstrates that seismic activity is not randomly located, but is generally located in linear bands. It is mostly confined to depths less than 30 km and is common near the crest of ocean ridges. However, in the linear bands that coincide with the deep ocean trenches, seismicity occurs in zones that dip into the interior to depths up to 600 km. These zones are always coincident with volcanic activity. Some seismic events are very large and would pose a hazard to developed infrastructure.

(18) Analyses of seismic waves that travel great distances in the interior demonstrate that Earth is, to first order, radially symmetric and confirms that it has a liquid core with an inner solid core, a nearly uniform mantle and a crust that is much thinner in the ocean basins than on the continents.

Physical principles emphasized: Waves, group velocity and phase speed, Shear and compression waves, Seismic ray propagation, tectonic structure.

Week 9, November 22nd (Thanksgiving, Thursday, Friday)

(19) The linear ocean magnetic anomalies are commonly symmetric about ocean ridge crests and have very similar spatial patterns for different ridges. This suggests a common origin for all anomalies. A time sequence of reversals of Earths geodynamo is suggested and successfully tested by the natural remnant magnetism in rocks and sedimentary cores. This proves that the ocean ridges are spreading. Most seismic activity is then easily reconciled with large-scale convective motion with downwelling associated with the deep events.

(20) Continents are then recognized as the product of differentiation during this process that produces material too light to return to the interior. Continental collision is the remaining major influence on surface structure.

(21) A spectrum of geophysical techniques are used to evaluate natural resource potential of the planet.

Physical principles emphasized: Geodynamics, Tectonic structure, dating techniques

Week 10

(22) Years of surveying show the existence of hurricanes, tornados, winter storms, fires, droughts. Some areas are more vulnerable than others. Surface surveys show the importance of temperate climate for nutrient production and sustainable agriculture

(23) Ice core studies are used to determine the climate history and its relation to the demise of the earlier civilization

Physical principles emphasized: Feedbacks, uncertainty

Week 11

(24) A review meeting is held to synthesize available information pertinent to the viability of a colony.

(25) Avoiding the problems that led to the demise of Earth’s former occupants and quantifying other potential difficulties is the main topic.

(26) Bring it all together and dealing with inevitable overflow.

Physical principles emphasized: Everything!