A Mixed Blessing…

Mars

This excerpt is from the The Home Library Cyclopedia Reference published in 1885.

Respecting the question of habitation, Richard Proctor says: “I fear my own conclusion about Mars is that his present condition is very desolate. I look on the ruddiness of tint as one of the signs that the planet of war has long since passed its prime. There are lands and seas in Mars, the vapor of water is present in his air, clouds form, rains and snows fall upon his surface, and doubtless brooks and rivers irrigate his soil, and carry down the moisture collected on his wide continents to the seas whence the clouds had originally been formed.” “…He has not yet, indeed, reached that airless and waterless condition, that extremity of internal cold, or in fact that utter unfitness to support any kind of life, which seem to prevail in the moon.

In the previous slide, rich detail about the surface conditions of Mars is provided. Although in 1885, direct information about the surface was unknown, I wonder if such speculation could be justified. In the upper left is a telescopic image from earth and in the upper right the image shown is a Hubble Space Telescope picture that was recorded when Mars was

at one of its closest approaches to earth

As we try to understand the nature of earth we need to recognize the dedication of those dreamers and realist that made space exploration of our neighbors possible. Remote sensing of the planets provides valuable information about our cosmic companions but without refined “ground truthing” real answers to our questions would evade us. The following hyperlinks show the detail we desire:http://jrscience.wcp.muohio.edu/movies/vmars3.mov

http://mpfwww.jpl.nasa.gov/MPF/parker/highres-anaglyph.html

Martian craters

Long tectonic stretched valleys (Note the lack of tributaries, meanders and the consistent valley width along its length.)

Volcanic mountains

River valleys

Craters lots some few Igneous extinct dormant activeActivity Plate none inactive activeTectonics  Surface old mixed youngAge

We must also acknowledge the kindness of Nature. Our studies show that the earth and moon are the extreme opposites of each other. One is dynamic while the other is static. Mars is a transition planetary body. The surface reveals regions that are very similar to the unchanging and heavily cratered moon. Mars also reveals an outer crust that features dormant volcanic mountains and water carved valleys.

Examine the following planetary data table. Which measurements reveal the low, mid and high trends we see in these planetary surfaces?

The trend reveals that the measurements-mass, diameter, density, surface gravity- all match the low, mid and high trends. These measurements in a word say:

SIZE MATTERS!

Distance from the sun is an essential factor contributing to the uniqueness of our home planet. But our study of planetary surfaces unveils a most remarkable revelation. Earth, in large measures, is earth because of its size! The earth and the moon, such polar opposite planetary surfaces, occupy essentially the same place in space. The average distance the moon orbits out from us is 240,000 miles. Mars at its closest approach to us is 35,000,000 miles away. To put this into perspective, consider the

following scale model for these distances.

Why would size be such a strong controlling factor in influencing the appearance of a planet in the inner region of our solar system? A planet’s surface is modified in three ways. Surface change results from bombardment from outside influences such as meteorites. An atmosphere generates modification through winds and the hydrologic cycle. It should also be noted that size is also a critical factor in the generation and retention of an atmosphere. Internal heat manifests itself through volcanic eruptions and internal stretching of the outer crust.

According to the above plot, the bigger you are the more internal heat you will generate and the longer you maintain the heat. More internal heat means a more active and changing surface.

Small Planet Size Large

Intern

al A

ctivity

High

Low

This seems like a reasonable way to understand what we see when we examine these planetary surfaces. We should be able to gain more confidence in our thinking by studying the following table. Predict the planetary surfaces you would expect for Mercury and Venus.

Venus does not allow us to view its surface directly. It is always covered by clouds. Such permanent cloud cover and its proximity to the sun lead earlier speculators to imagine Venus as a tropical twin sister to earth. However, recent mapping techniques reveal a nearly craterless surface. Crustal features show an active heat generating interior.

As expected Mercury looks like the Moon. Although small, unlike the moon its density and magnetic field suggests an iron core.

As the above diagram shows our intuitions are confirmed. The bigger the terrestrial planet the younger is the age of its surface.

Small Planet Size Large

Intern

al Activity

High

Low

COMPARATIVE PLANETOLOGY

 

From our studies of Earth, Moon, Mercury, and Venus, we can derive three general

principles that will clarify phenomena of other planets as well:

 

1. The larger the planet, the more internal geological activity there is likely to be.

Internal heat is the energy source that drives geological activity such as tectonic

faulting, earthquakes, and volcanism; the larger a planet, the more radioactive minerals

it contains and the more radioactivity there is to release heat. Also, the larger a planet,

the better insulated the interior and the harder it is for the heat to escape. Small planets,

on the other hand, cool rapidly and lose whatever heat they may have generated. Earth,

unlike Mercury and the Moon, has enough internal energy to drive plate tectonics.

 

2. The larger a planet is, the younger its surface features are likely to be. This principle

follows from the one above. The more internal heat, the thinner the lithosphere and the

more likely it is for the lithosphere to be broken by recent geological activity. Small

planets that cooled long ago retain very ancient surface features. Earth and probably

Venus retain fewer ancient craters than Mercury and the Moon.

Source: Astronomy the Cosmic Journey by Wm. Hartmann

The thinking in 1885, “The earth will then, in all probability, be as dreary as the moon is now”, suggests that the condition of the moon is our destiny. This is not the case. The moon is a fossil that preserves our past. The nearly unchanged moon is a record of the early bombardment era of the Condensation Model for the origin of the system. As a larger gravitational body the earth would have attracted more of the planetesmials from the cloud of gas and dust that gave birth to the sun and the planets. As we shall see our planet’s future may best be represented by Mars. The contents of the entire solar system essentially formed at the same time, yet each planet is unique. By studying their individual history of development we are able to better interpret the clues they provide to unraveling the story of our own planet.

Occasionally on the bumper of the car ahead of you the placard reads, “Reunite Pangaea,” or, “Stop Continental Drift Now!” You probably react to this call for action as I do. In my mind I think, “What can I as one person do?” After such a mental reminder to this global problem, I find myself getting lost in the business of my life. In my self-centeredness, I live for the moment so I take no action. As a member of the, “Be young, Have fun, Drink Pepsi Generation,” I am comforted by knowing that this is a problem I am willing to let my children solve.

 

In my mind, one of the strangest realizations about our planet is that the distribution of the land masses and the ocean basins do not stay fixed over time. This is how a planet like the earth responds to the release of the internal heat it generates and stores. As you watch the movie at the hyperlink that follows, remember that about 700 million years are shown condensed in the time that it runs. The distribution of the land masses on the planet has great impact on the development of biological environments, air and ocean circulation patterns and many other features about our world we take for granted. How has all of this chaotic planetary behavior influenced the development of intelligent life on this planet?

 

Note: To run/re-run the movie, double click left on the mouse.

http://cmex-www.arc.nasa.gov/cmex/data/catalog/TectonismonMars/PlateTectonicsOnEarth.html

PLATE TECTONICS IS A KEY TO THE EVOLUTION ANDPRESERVATION OF COMPLEX METAZOANS ON EARTH Source: Rare Earth 

• Plate tectonics promotes high levels of global biodiversity. The major defense against mass extinctions is high biodiversity. It can be argued that the factor on Earth that is most critical to maintaining diversity through time is plate tectonics.

• Plate tectonics provides our planet’s global thermostat by recycling, chemicals crucial to keeping the volume of carbon dioxide in our atmosphere relatively uniform, and thus it has been the single most important mechanism enabling liquid water to remain on Earth’s surface for more than 4 billion years.

• Plate tectonics is the dominant force that causes change in sea level, which, it turns out, are vital to the formation of minerals that keep the level of global carbon dioxide (and hence global temperature) in check.

• Plate tectonics created the continents on planet Earth. Without plate tectonics, Earth might look much as it did during the first billion and a half years of its existence: a watery world, with only isolated volcanic islands dotting its surface. Or it might look even more inimical to life; without continents, we might by now have lost the most important ingredient for life, water, and in so doing come to resemble Venus.

• Plate tectonics makes possible one of Earth’s most potent defense systems: its magnetic field. Without our magnetic field, Earth and its cargo of life would be bombarded by a potentially lethal influx of cosmic radiation, and solar wing “sputtering” (in which particles from the sun hit the upper atmosphere with high energy) might slowly eat away at the atmosphere, as it has on Mars.

 

Sometimes you will notice inside the hardness of an ice cube that there is a bubble, a pocket, of air trapped inside of it. When a volcano erupts on the earth huge volumes of gases are released. These gases are responsible for the often explosive nature of the eruption. As the gases are carried upward from below, the pressure decreases. As the pressure is relieve the gases expand. Molten rocks, like the ice mentioned above release these ingredient gases contained within them. Atmospheres are created and renewed by this outgassing process. Comets too have been responsible for the addition of volatiles to our planet.

The ability for a planet to retain an atmosphere is related both to its size and its position from the sun. The gravitational strength of a planet, determined by its size, influences your ability to throw an object into the air. Think again about water, if as a liquid it becomes too hot, it evaporates. If it becomes too cold, it transforms into a solid. Distance from an energy source has a strong influence on surface chemistry.

COMPARATIVE PLANETOLOGY

Source: Astronomy the Cosmic Journey by Wm. Hartmann

The larger and cooler a planet is, the more likely it is to have an atmosphere, and the more likely this atmosphere is to have retained its original gases.

The planets probably formed with an initial gas concentration called a primitive atmosphere, which changed to a secondary atmosphere as new gases were added by out-gassing. Why, then, do some planets lack atmospheres whereas other planets have dense ones? The explanation comes from three principles that govern the motions of gas molecules in atmospheres:

1. The higher the temperature, the higher the average speed of the molecules.

2. The lighter the molecules, the higher their average speeds. Light gases like hydrogen and helium have faster average speeds than heavier gases such as oxygen, nitrogen, carbon dioxide, or water vapor.

3. The larger the planet, the higher the speed needed for a molecule to escape into space.

 If you could heat a planet’s atmosphere, more and more molecules would move faster than escape velocity, and fast-moving molecules moving upward near the top of the atmosphere would shoot out into space, never to return. First hydrogen, then helium, and then heavier gases would leak away into space. Cold, massive planets are most likely to retain all the gases of their primitive and secondary atmospheres; hot, small planets (with weak gravity and low escape velocity) are most likely to lose all their gases. Calculations based on these principles show that planets as small as Mercury and the Moon have lost virtually all of their gases. Venus and Earth have lost most of their hydrogen and helium but have kept heavier gases.

THE TEMPERATURE OF PLANET’S SURFACE

IS A FUNCTION OF SEVERAL FACTOR

Source: Rare Earth

1) Related to the energy coming from its sun.

2) Is a function of how much of that energy is absorbed by the planet (some might be reflected into space, and this relationship is dictated by a planet’s reflectivity, or albedo.)

3) Is related to the volume of “greenhouse gases” maintained in a planet’s atmosphere.

  Greenhouse gases have a residence time in any atmosphere and are eventually broken down or undergo a change in phase. If their supplies are not constantly replenished, the planet in question will grow colder gradually until the freezing temperature of water is reached, at which point it will grow colder rapidly.

 

It turns out that the internal heat behavior of our planet manifested in the crustal movement, volcanic eruptions and the other behaviors associated with plate tectonics has a lot to do with how comfortably you sleep during the night. The earth needs to regularly replenishes greenhouse gases such as water vapor and carbon dioxide. These gases are the thermal blanket you slumber under when you face away from the sun. Zzz

To deepen your understanding of this very important planetary cycle, go to the class contents section and read: Carbon Cycle by Paul Olsen.

The circulation of carbon helps us better understand earth and our planetary neighbors Venus and Mars. Perhaps somewhere in these two explanations lies the ultimate fate of our planet. The summary presented in the next few slides comes from Dr. Dale Cruikshank.

Essential Points About Venus

1.The surface is very young; the average age is 300-750 million years (less than 10% of the total age of the planet).

2.Venus has had massive, recent volcanism.

3.The topography on Venus is very low, perhaps as a result of the high temperature of the crust.

4.Venus had an early “water history”, but the water did not permanently trap large quantities of CO2. Why?

5.Tectonism on Venus results in large crustal cracks, and circular features from upwelling from the mantle. There is no plate (horizontal) tectonics in the current epoch.

6.How, in detail, does the history of Venus differ from that of its twin, Earth?

Venus: The Runaway Greenhouse

 

Early Venus (~4 billion years ago):

         Moderate temperatures

         Water ocean

         CO2 dissolved in the ocean, or chemically combined with surface rocks.

An equilibrium condition prevailed

Then: Increase heating as the Sun brightened, or additional

CO2 was somehow deposited in the atmosphere

Consequences:

         Oceans begin to evaporate, liberating CO2 into atmosphere

         H2O in the atmosphere contributes to more heating

         CO2 gas is released from surface rocks

         The atmosphere and surface heat up through a

strengthening greenhouse effect

         Heating liberates more CO2 from the ocean and rocks, and temperatures continue to rise.

This is a Runaway Greenhouse Effect

Modern Venus:

         No water oceans

         Massive, CO2-rich atmosphere

Surface temperature of 467 Celsius (or 873 Fahrenheit)

Mars: Climate Change and the

Runaway Refrigerator Effect

 

Early Mars (~4 billion years ago):

•Water on the surface, in lakes, an ocean, and in glaciers

•Moisture in the atmosphere, with clouds, rain and fog

•Floods occurred

•Temperature moderate

•Denser, CO2-rich atmosphere, warmed by a greenhouse effect

•Life may have originated

The climate began to change…

•Weaker gravity on Mars allows gas to escape

•Late impacts from the nearby asteroid belt may have blasted away a significant part of the atmosphere

•As the atmosphere began to thin, the greenhouse effect weakened, and the planet began to cool

•When the water finally froze, the temperature dropped even more (atmosphere unable to retain heat from the Sun)

This is the Runaway Refrigerator Effect

Modern Mars:

•No water oceans; no rain has fallen for at least 3 billion years

•Very thin CO2-rich atmosphere

•Surface temperature in range –33 to –100C (-27 to –150 F) [Even colder at the poles]

Mars’ remaining water is locked up as ice in the polar caps and under the surface as “permafrost”

Pictures like these show that currently Mars has a very thin air layer dominated by CO2. Surface atmospheric pressure is 1/100 of what we experience on earth. This thin shield means that harmful energies are generally not filtered out.The water carved surface features suggest a past Mars that had enough atmospheric pressure to sustain liquid water on its surface. A thicker atmosphere,supplied by volcanoes, would create a more favorable temperature environment. Mars some have suggested was a watery world as shown in this artistic rendering

Life is a tenacious by product of the universe. Although one can not rule out present day Micro-Martians, the past environmental conditions would have been more favorable than they are today. This is known, the first person on Mars is already alive on planet earth. Stay tuned…

Did you know that there are as many microbes in a single gram of soil as there are people in China? Moreover, one gram of soil may contain 10,000 different species of microorganisms. There is more diversity in a gram of soil than there is in all of the different types of mammals in the entire world. (Source:unknown)

For more information see the following hyperlink:

http://commtechlab.msu.edu/sites/dlc-me/

Living things are extraordinarily resilient, especially simple ones. Bacteria can survive extremely hostile conditions; some have been found alive at the base of glaciers, and even inside solid rock. Unknown to the authorities, a small colony of Streptococcus mitis hitched a ride to the Moon in 1967 inside an Apollo TV camera, and the bacteria were still alive three years later when the camera was brought back to Earth. They had managed to survive without food, water or even air.

(Source: New Scientist)

The following about the exploration of Mars comes from other sources.

MARS HABITAT CONSIDERATIONS

Information provided by

Dr. Ronald Thomson, UW-Madison

  * There is severe radiation on Mars. No living organism or delicate equipment will be able

to survive long exposures without sustaining damage.

 

* Mars has high winds. Seasonal dust storms take place over much of the planet. The dust

storms on Mars have different effects than those on Earth because of low Martian

atmospheric density.

 

* Most missions currently proposed are intended to land + or – 20 degrees from the equator.

 

* The Martian temperature fluctuates yearly.

 

* The Martian atmosphere is primarily carbon dioxide. It could possibly be a source of

oxygen for astronauts.

 

* Water ice can sometimes be found at one or both of the Martian poles, but will probably

not be readily available to astronauts. Probably the best source of water on Mars will

be the atmosphere which has traces of water along with argon and nitrogen.

 

* There may be permafrost on Mars. This could affect digging or possibly be another

water source.

 

* There will be a considerable delay in speed of light communication with Earth because of

the distances involved.

 

* Note the length of the Martian day and year.

 

* Remember that Martian windows occur approximately every two years and you can’t go

or return whenever you want to.

 

* The per/pound cost to transport a mass to Mars is not cheap and space in the cargo bays is

severely limited. These are major considerations in any design decision.

The radiation environment of Mars is very inhospitable to all forms of life. The main types of radiation include photons, neutrons, electrons and ions. Many radiation particles, mostly the ionizing radiation, are very destructive to cells and structures when large amounts are absorbed. Since Mars has no magnetic field and a very thin atmosphere, the radiation cannot be weakened or deflected, and the radiation flux is similar to that of free space. There are two major sources of radiation that reach the surface of Mars: Galactic Cosmic Rays (GCR) and Solar Particle Events

(SPE). GCR originate from outside the solar system and have a steady flux intensity. The annual dose equivalent due to GCR on the surface of Mars is about 30 REM/yr. Small SPE (solar flares) occur frequently and large ones occur in approximate 11 year cycles lasting only 2-3 days. However, these gigantic SPE are extremely hazardous: each bombards the Martian surface with a dose equivalent of about 1000 REM—fatal to human life and most plant life and extremely

damaging to electronic circuits.

 

GCR and SPE also penetrate the Martian surface. The actual depth of penetration depends on

the density of the surface material. A general approximation is:

Depth GCR (REM/yr) Major SPE (REM/event)

 

1 m 12.2 122.

2 m 6. 60.

3 m 1.2 16.

4 m .34 3.4

LIVING OFF THE LAND

(Source: Scientific American Frontiers)

 

 

Engineer Robert Zubrin has worked out step-by-step plans for a Mars mission at a relatively low cost. One of his basic principles is living off the land and using local resources. Zubrin shows how rocket fuel could be made out of raw materials in the Martian atmosphere. In the Mars chemical plant, the Sabatier reaction combines carbon dioxide with hydrogen to produce methane (which forms the basis for methanol rocket fuel) and water (CO2 + 4H2 CH4 + 2H2O). After water (H2O) is obtained, it can be separated into its two components, hydrogen and oxygen. Similarly, scientists have proposed that oxygen can be obtained from ice on the moon. In Zubrin’s plan, oxygen is stored as rocket propellant, and the hydrogen is recycled back into the chemical plant to make more methane and water. The methanol would also be used by Mars rovers as fuel. Zubrin also has a plan for making ethylene (C2H4) – another fuel and the basis of plastics – out of carbon dioxide and hydrogen.

How might caloric and nutritional needs be met on a long space flight? Currently, astronauts are limited to less than four pounds of food per day, plus another pound for packaging. Calculate the weight of food products for six months of typical meals,and you’ll understand why astronauts on long missions would have to rely on recycling and foods grown in the spacecraft.

Temperatures on Mars fluctuate wildly. For reasons science does not completely understand, the temperature drops dramatically only a few feet above the surface of Mars in the daytime. If you stood on the surface, your feet would be warmer than your head in the daytime. Typical daytime temperatures at the surface range between –50 degrees C and 10 degrees C, but can go as high as 18 degrees C, and drop as low as –90 degrees C at night. At five feet above the surface, temperatures range between a daytime high of about –9 degrees C and a nighttime low of –76 degrees C.

PSYCHOLOGICAL EFFECTS OF WEIGHTLESSNESS

ON THE HUMAN BODY

(Source: Unknown)

 What effects does living in weightlessness have on the human body? Microgravity has

been shown to change bone composition, decrease muscles size, shift fluids to the upper

body and alter heart size and blood composition. All of these changes are thought to be

reversible once astronauts are back on Earth.

 

The Skeletal System

During space flight, the bone minerals, calcium and phosphorus, are slowly lost. Much of this loss is thought to occur in those bones that maintain erect posture and aid in locomotion.Those bones primarily effected are the spine and legs. When calcium leave the bone matrix, it is transported by the blood to the kidneys for excretion. Calcium buildup in the kidneys may result in the formation of painful kidney stones during flight. Bone tissue contains a fibrous protein called collagen. Studies have shown that dehydration can change the structure of collagen and lead to a reduction in mineralization. The loss of bone strength poses a risk of bone fractures for crews on long-term missions. One noticeable effect of long-term space flight is an increase in height. Lack of gravity causes the cartilage between the vertebral disks to expand. An astronaut upon landing may be up to an inch taller than before launch.

The Muscular System

Muscles rely on gravity to maintain normal strength, mass and function. Muscles are used by the body to maintain an upright position against the pull of gravity. The weightless environment of space decreases the work that muscles must do just to keep the body upright. Without exercise these muscles will decrease in size, a condition known as atrophy. The only known preventive to muscle atrophy is regular exercise on stationary bicycles and treadmills on board spacecraft.

 The Cardiovascular System

The cardiovascular system transports blood throughout the body, assists in temperature regulation and delivers oxygen and food to cells while removing wastes. In performing these body functions, blood interacts with all body systems. Thus the effects of a weightless environment on the cardiovascular system influence all other parts of the body. On Earth, a person is continuously subjected to the acceleration force of gravity that tends to pull body fluids toward the feet. Continuous muscle contractions in the legs, one-way valves in the veins and the pumping of the heart assist circulation and prevent permanent collection of fluids in the feet. Body fluids shift head ward in microgravity, since there is no force of gravity to pull them down. This upward movement of fluids has led astronauts to describe their lower extremities as “bird legs.” Subsequent migration of fluids to the upper body causes tissues of the head and neck to swell and the blood volume handled by the heart to increase. The tendency toward lower heart rates during space flight shows that the heart may have enlarged to accommodate its increased workload.The cardiovascular system also adapts to space flight by losses in blood plasma and in red cell mass to compensate for the increased blood volume in the upper body. This condition has been called “space anemia.” The increase in upper body fluids causes heads to become congested. When the fluids shift back upon sudden re-entry into a gravity field, space crews often experience dizziness or are unable to stand upright. Astronauts say that this shift in fluids to the lower extremities makes them feel as if they have “elephant legs.” Returning to Earth reverses adaptation of the cardiovascular system. The size of the heart is noticeably decreased and its rate increased to pre-flight levels.

Exploration of the planets offers humanity several important advantages. Problem solving is a cultural stimulus that is crucial to the vitality of societies. Space exploration requires us to be forward thinkers. There are available natural resources. But perhaps Stephen Webb reminder about the fragility of life itself is most important. He says, “The space environment can be a deadly place. In recent years we have come to understand what a dangerous world we inhabit. Things have been peaceful here on Earth over the short span of recorded human history. Believing the world is calm because we have never seen otherwise is like taking the attitude of a man who jumps off the top of a tall building and figures that, since 29 of the 30 floors have passed without incident, he is going to be okay. Having our genetic material in the form of colonists on another world may not be such a bad idea. A species with all its eggs in one planetary basket risks becoming an omelet.”

When Jupiter is examined with the telescope it will be seen that he is crossed by belts of vapor; and when we consider the results of the spectrum analysis of the planet, we may fairly assume that Jupiter is in a very heated state, and that we cannot really perceive the actual body of the planet. There is an immense quantity of water thus surrounding Jupiter, and he seems to be still in the condition in which our earth was before geology grasps its state, and long ere vegetation or life appeared. The waters have yet to be “gathered together into one place,” and the dry land has yet to appear. Under these conditions we can safely assume that there are no inhabitants on the “giant planet.” The belts or zones of Jupiter vary in hue, and the continual changes which are taking place in this cloud region tend to show that disturbances of great magnitude and importance are occurring.

 It is useless to speculate upon what will happen in Jupiter when the disc is eventually cooled. The planet, we know, has not nearly reached maturity; the earth is in the full prime of its life; and the moon is dead and deserted. What the millions of years which must elapse before Jupiter has cooled may bring forth we need not try to find out. The earth will then, in all probability, be as dreary as the moon is now, and we shall have returned to dust.

In our planetary study we have indeed found a kinship with our planetary cosmic cousins. Their story is our story as every thing we know in the shallow depths of space we call our Solar System was born in a great nebula of former stellar debris. Although all of us come from the same stock each expresses its own individuality. Unlike the thinkers of 1885, we no longer expect these planets to emulate the history of our abode…

A Mixed Blessing…

You seen one Earth, you’ve seen them all…Harrison Schmidt, walking on the Moon during Apollo 17.Quoted by astronaut Gene Cernan, Last Man On The Moon (p.324)

Credits:Larry Mascotti