----------------------- # 1620 - Is there water on other planets?
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- What is the likelihood of finding life elsewhere? Water is a key ingredient. How did water arrive on Earth? What conditions are needed for life to exist?
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- (1) Life must react, change, with its environment. It must recover, heal itself, when damaged.
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- (2) Life must reproduce and pass on its genetics to an offspring. Genetics must continue to mutate and adapt over many generations.
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- (3) Life gets food out of the environment and converts it to energy to run the body.
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- (4) Doss life need water? Maybe not, but liquid water sure seems to be a key ingredient. Water is the solvent for life.
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- Where can life exist? We know only one place, Earth. But, Earth is just one small planet orbiting one ordinary star. There are billions of stars in the galaxies and there are billions of galaxies in the observable universe.
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------------- 1,000,000,000 * 1,000,000,000
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- There are at least as many planets as there are stars. If only 10% of these planets are habitable that only drops one zero off that string of zeros:
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--------------------------- 1,000,000,000,000,000,000.
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---------------------------- 100,000,000,000,000,000
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- There remains an enormous amount of opportunities for life elsewhere. The elements of the Earth are found in the Sun and in the other moons and planets. All have common molecules that evolved life for us. Life on Earth is based on five elements carbon, oxygen, hydrogen, nitrogen, and phosphorus. These elements exists everywhere the universe.
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- The laws of physics appear to be the same everywhere in the universe. The universe is billions of years old. Given enough time life must have evolved in other places. The conditions for life are not hard to duplicate.
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- Astronomers have discovered over 1000 planets orbiting in other solar systems. They are anxiously studying these exoplanets to learn which ones are likely habitable.
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- We are ever studying the moons and planets in our own solar system to see if life can be discovered closer to home.
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- A spacecraft has been orbiting the planet Mercury since March 2011. The spacecraft is named: MESSCENGER = MErcury Surface Space ENvironment GEochemistry and Ranging.
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- Mercury rotates 3 times in its on its axis for every 2 revolutions it makes around the Sun. It is tidally locked to the sun's gravity, but, not one-to-one like our moon is tidally locked to the Earth's gravity. Mercury experiences in a Mercury "day" every 2 Mercury "years". A 3 : 2 resonance has great effects on the planet's temperature. Where the sun lasts for long periods of time the temperature rises to 725 Kelvin, which is 845 Fahrenheit.
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- Mercury's axis tilts almost 90 degrees to its orbit plane (89.99°). With this perpendicular orientation the poles can remain in permanent shadows. Their deep polar craters represent the coldest surface temperatures astronomers have explored. When Messenger was able to collect data on the surface at the poles astronomers determined that water ice has lasted there over billions of years.
- The water ice was covered by 10 centimeters of material that is best matched to the organic rich dust found in comets and meteorites. There is no evidence that this ice ever reaches the liquid state. Mercury has no atmosphere so even if liquid water could briefly form it would quickly boil away into space.
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- The Messenger spacecraft is progressively orbiting closer to the surface to gather more precise data. It will descend to within 15 miles altitude. If we could get a lander on the Mercury we could learn if the ice exists in successive layers with the oldest at the bottom. It could provide a time lapse history of Mercury the same way ice cores from Antarctica is able to study Earth's climate history.
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- 70% of the Earth's surface is covered by water, H2O. It could not have been here during the Earth's formation. The planet was too hot in the beginning. Volcanoes were everywhere. Somehow water got delivered to Earth after it cooled down.
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- Actually the rocky inner planets, Mercury, Venus, Earth, and Mars have very little water compared to the rest of the solar system. However, beyond the orbit of Mars water is abundant.
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- Saturn's rings contain 26 million times as much water as Earth.
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- An average comet contains several billion tons of water ice.
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- About 10% of the asteroid belt between Mars and Jupiter is water. Ceres is an asteroid with an ice layer 75 miles thick containing more freshwater than all the freshwater on Earth.
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- 4.6 billion years ago the planets first formed out of the gas and dust accretion disk that orbited the infant Sun. The dust settled toward the midplane and the planetisimals formed. Outside an orbit boundary, called the "snowline", water condensed. It was far enough from the Sun to avoid being evaporated.
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- - When planets first formed the inner planets were dry. While the outer Asteroid Belt contained lots of water. When the giant planet Jupiter migrated to a higher orbit its gravity kicked many asteroids into the inner solar system. When these asteroids impacted inner planets they brought their supply of water.
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- The formation of the planet Earth cannot have contained water until it cooled down. Between 4.2 and 3.8 billion years ago comets bombarded the planet and brought the water. Here is how it could have happened given 400,000,000 years:
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- Comets come in various sizes. The smaller ones impact more frequently and the larger ones are rare occurrences. That's a good thing.
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---------------- Comet diameter in kilometers ------------------ Interval of impacts ----
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------------------------------ 2 --------------------------------------------- 6 months --------
---------------------------- 20 ------------------------------------------- 600 years ---------
--------------------------- 200 ------------------------------------------1,000,000 years ----
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- The Earth has 1,330,000,000,000 cubic meters of water. The comets are solid ice which is 6 times the volume of liquid water. Ice expands.
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------------ 6 * 1.33*10^9 = 8*10^9 cubic kilometers of ice required.
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----------- The average number of comet impacts per year = 8*10^9 / 400*10^6 = 20 cubic kilometers of ice required on average each year.
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---------- Volume, km^3 -------------- Interval, years ----------- volume/year ----
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---------------- 4.2 --------------------------- 0.5 ------------------8.4 km^3 / year ---
---------------4,200 ------------------------- 600 --------------------7.0 -----------------
-------------4,200,000 --------------------1,000,000 -------------- 4.2 ----------------
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------- TOTAL: ------------------------------------------------------20 km^3 / year
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- 8*10^9 km^3 ice / 20 km^3 per year = 400,000,000 years. Therefore, that combination of comets would fill the oceans of the Earth. It’s in the math.
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- Earth has hundred thousand times more water than Venus and Mercury has only a little water hiding in its several deep craters. Even the moon is still hiding a little water at its poles. Water must be hidden from sunlight. As liquid H2O it cannot survive solar radiation. However ,in a different form the moon has 7,500,000,000,000 gallons of water
- Clinging to the regolith at the surface are billions of gallons of water. The discovery was made of hydroxyl molecules which consist of one atom of oxygen and one atom of hydrogen. To get water simply add another atom of oxygen, H2O. The hydroxyl molecule was discovered due to its absorption of infrared light with a wavelength of 3,000 nanometers. It was detected in the top 1 millimeter of the Moon’s surface.
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--------------- The radius of the Moon is 1,731 kilometers ,”r”.
-------------- The surface area is 4 * pi * r^2 = 3.7 *10 13 cubic meters
-------------- Times 1 millimeter thick = 3.76 *10^10 cubic meters
--------------- Density at the Moon’s surface = 3,000 kilograms / meter^3
-------------- Mass = volume * density = 1.13*10^11 metric tons
-------------- Concentration of water = 1 liter per metric ton.
-------------- 25% of surface can be mined.
-------------- 1.13*10^11 * 1 * .25 = 2.8 * 10^10 liters of water
-------------- 1 gallon = 3.78 liters.
--------------- 2.8 *10^10 / 3.78 = 7.5*10^9 gallons of water.
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- The Moon has 7,500,000,000 gallons of water.
- - Deuterium is a heavy isotope of hydrogen. It's nucleus contains a neutron in addition to the single proton. When solar radiation splits water into hydrogen and oxygen the lighter hydrogen escapes into space. The oxygen remains and combines with other elements. The amount of deuterium left in the atmosphere provides an excellent gauge of how much hydrogen was lost into space and therefore how much water was evaporated.
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- Venus has a ratio of deuterium to hydrogen that is 100 times higher than Earth's ratio. Venus definitely had more water in its past.
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- Mars too has abundant evidence of water in its past. Mars lost its water because it is too small. There is not enough gravity to hold it in the atmosphere. Even the impacts of asteroids and comets resulted in blasting most of Mar's atmosphere into space.
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- It is s unlikely that our water came from the comets in the outer solar system. Jupiter is simply too great a gravitational barrier for them to make the trip. It is far easier for asteroids between Mars and Jupiter to get kicked into the inner solar system to bombard the rocky planets.
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- In addition the deuterium to hydrogen ratio of the outer comets does not match that found on Earth. In contrast the ratio found in asteroids is a perfect match. For example: Deuterium in Earth’s oceans is 0.015%. Deuterium in Hartley-2 comet was 0.016%
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- Jupiter's moon Europa is suspected to have a subsurface liquid ocean kept warm by the gravitational tides interacting with Jupiter. Surface ice is 6 to 18 1/2 miles thick. The liquid water below that could be 60 miles deep.
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- Saturn's moon Enceladus has water geysers and likely a subsurface liquid ocean.
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- Titan has an abundance of water in the form of rock hard ice. 56 miles thick below this is a water – ammonia ocean 250 miles deep.
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- The Kuiper Belt beyond Neptune orbits the Sun with vast amounts of water. And, beyond that is the Oort Cloud of comets is where water is plentiful.
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- Water, water everywhere, but not a drop of life? I don’t think so. An announcement will be made shortly stay tuned.
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