Archive for the ‘Close To Home by Evan Finnes’ Category

Large Deposits of Water-Ice Found on Mars

Monday, November 24th, 2008 by Evan Finnes

On November 20th, 2008, NASA confirmed that the Mars Reconnaissance Orbiter has discovered ancient glaciers of water-ice preserved under a layer or dust and rock. These subsurface glaciers are located at altitudes much lower than any previously discovered layers of ice, and also contain more water-ice than any other region on Mars, including the poles.

These glaciers were discovered underneath a formation that had been puzzling geologists for years. These formations are known as “aprons” because of the way they gently slope upwards. The glaciers were discovered after ground penetrating radars were pointed at these “aprons” because the radio waves were reflected without a significant loss of energy shortly after penetrating the surface. The radio waves that are not reflected travel through these formations with an apparent velocity, which is consistent with the composition of water-ice.

Hundreds of these apron-like features are located in latitude bands between 35 and 60 degrees on either side of the Martian equator. They are also commonly located beneath cliffs and are typically tens of kilometers long, and may be the remnants of a giant ice sheet, which may have at one time engulfed these mid-altitude regions. Many scientists believe that Mars was once tilted in such a fashion that the poles pointed toward the Sun, leaving the mid-latitude regions in a much cooler climate. This discovery offers proof to this hypothesis.

Studying these ice-sheets could help us understand processes that effect climate change, which is a poorly understood phenomenon, here on Earth. Our last glacial Maximum occurred about 20,000 years ago, when much of the North American and Eurasian continents were covered in an ice sheet over 3 kilometers thick. There are many factors which are thought to cause the onset of an ice age, such as: changes in the atmosphere, tectonic geography, variation in the Earth’s orbit, and variations in solar energy. The changes in the atmosphere which effect the onset of glaciers is not well understood, although, there is some proof that CO2 levels shrink during the onset of an ice age, and increase during interglacial periods. The effects of increased CO2 on the climate have long been a subject of great debate. Tectonic geography affects the onset of ice ages by arranging the continents in such a way that they prevent the flow of warm water from the equator to the poles; this allows the formation of ice sheets. These ice-sheets increase the planets albedo, which decreases the amount of solar radiation, which is absorbed. This decrease in absorbed energy allows the ice sheets to expand. There are three known configurations which block or reduce this flow of warm water–two of which exist today. A continent sits on top of a pole, such as Antarctica. Or a polar sea, such as the Arctic Ocean, is nearly land-locked. The third configuration consists of a single mass continent which covers much of the equator. Such a mass continent existed between 850 and 635 million years ago during the Cryogenian period, and was called Rodinia. Variations in the Earth’s orbit, called Milankovitch cycles, suggests that major ice ages occur every 100,000 years due to periodic changes in Earth’s eccentricity, axial tilt, and orbital periods; however, how these variations effect the climate are not well understood.

The discovery of these large volumes of water-ice on Mars will be very important to the future colonization, and manned missions to mars. This ice will serve as drinking water, and as a source of energy, which will be used in hydrogen fueled vehicles. This will defiantly reduce costs for such future missions because fewer supplies will have to be shipped to the red planet.

On Earth, such buried glaciers in Antarctica preserve traces of ancient organisms. So these Martian glaciers might also serve as a place to look for fossil evidence of past life on Mars. In addition to fossil life, localized heating due to volcanism may have melted some ice, which could provide an environment for microorganisms to evolve.

The discovery of subsurface glaciers on Mars will help us understand the processes which evoke climate change on Earth, provide a place to gather food and fuel for future missions to Mars, and could be one of the best places to look for signs of ancient organisms. Indeed, these will be places which will be thoroughly explored by rovers, Landers, and eventually, by mankind.

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Wednesday, November 19th, 2008 by Evan Finnes

Earlier this year, India celebrated the launch of its first mission to the moon. The mission is called Chandrayaan-1, which in Hindi, translates to “trip to the moon”. The mission was launched on October 22, 2008 using India’s own launch craft which is called the Polar Satellite Launch Vehicle. On November 8th, Chandrayaan-1 entered a lunar orbit at altitude of 100 km above the lunar surface.

Chandrayaan-1 is a multinational program with contributions from India, NASA, the Bulgarian Academy of Science (BSA), and the European Space Agency (ESA). The objective of this mission is to map out the lunar surface in greater detail than has ever been done before, by any single nation. This mission will Map out, in high resolution, the chemical and mineralogical compositions of the Moon’s North and South poles. It will also search for pockets of surface and subsurface helium, and water-ice which could be potentially used by a future Moon-base. The satellite will also map out changes in elevation, and the chemical composition of the moons interior by observing internal rock which has been exposed to the surface. It is hoped that the data gathered will help develop a better understanding to the evolution of the solar system, particularly, the origin of the Moon.

With the great success of Chandrayaan-1, the Indian Space Research Organization (ISRO) has announced plans for the launch of Chandrayaan-2 in 2011. For this relatively short mission (with a duration of approximately one month), the Russian Federal Space Agency (Roskosmos) will join the ISRO in the building of a lunar Lander/Rover. This mission will be very similar to NASA’S Martian Sample Return Mission, due to the fact that a solar powered rover would navigate across the lunar surface, collect samples and return them to an orbiting spacecraft, which will bring them back to Earth. The ISRO also has plans to launch Chandrayaan-3, 4, and 5, but the details of these missions have not yet been announced. Could India be planning a manned mission to the moon?

The reason we are still so interested in the moon is because of the fact that we still do not fully understand the processes which may have formed the moon. The leading hypothesis, developed by geologist Reginald Aldworth Daly, suggests that during the formation of our solar system, a hypothetical mars sized body called Theia smashed into proto-Earth. This collision would have caused Theia’s entire mantle, and most of Earths to explode into space, while Theia’s iron core sank into the Earth where it combined with Earths Iron core. The mantle debris, in orbit around the Earth, then would have accreted to form the current moon. This hypothesis also explains the unusually large size of Earth’s core. There is some evidence which supports this hypothesis: the lunar rocks gathered during the Apollo mission were found to contain oxygen isotopes with compositions very similar to Earth. Also, large areas of the lunar surface appear to be igneous, which means that it was once molten, and the energy produced during a large collision would be high enough to produce large scale melting of lunar rocks.

It is always exciting when other nations become more involved with space exploration, and contribute more to the collective knowledge of our surrounds. It will be interesting to see if Chandrayaan-1 will be able to produce data that will confirm the Giant Impact Hypothesis, or discover that there is enough water on the lunar surface to support a space colony. Hopefully the ISRO will be able to further expand its space program, despite critics of India’s government, who wish to have the bulk of the space exploration funds reallocated to social welfare programs.

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Monday, November 17th, 2008 by Evan Finnes

Since the dawn of intelligent man, we as a race have asked several questions pertaining to the heavens, and to the meaning of life. A NASA mission, scheduled to launch in March 2009, hopes to take us a step closer to answering one of these timeless questions: “are we alone?” The Kepler Mission is not only named after the great mathematician and astronomer, Johannes Kepler, it also celebrates the 400th anniversary of the publication of his first two laws on planetary motion.

Some of the goals of the Kepler Mission include: determine the percentage of terrestrial planets in the habitable zone of nearby stars; determine the period and geometries of any such discoveries; discover any additional members of the planetary system to which the habitable planet belongs; and to determine the properties of the planetary systems host star.

To help celebrate this mission, and the 400th anniversary of the publication of Kepler’s work, NASA is taking names from the public to put on a DVD which will orbit the Sun onboard the Kepler spacecraft. Anybody who wishes to submit their name must write a short essay, under 500 words, explaining why they personally believe the Kepler mission is important. So why is this mission important? There are at least three reasons why this mission is important: #1) Are we alone in the universe? Mankind has been pondering this question for centuries, and by discovering habitable planets outside of our solar system, we will be much closer to answering this question. The discovery of such a planet will dramatically affect our scientific and religious communities; the discovery of one such planet will create a montage of new questions; #2) Eternal life. If the human race wishes to outlive the life of our host star, we will eventually have to colonize a planet outside of our own solar system. The first step, in this thankfully very distant journey, is to map out the habitable planets in our galactic neighborhood. #3) Planetary evolution. By discovering Earth-like planets existing around several types of stars, in several stages of their lives, we will be able to better understand the processes which shape planetary evolution, and the development of life.

The Kepler spacecraft will not orbit the Earth, but will orbit the sun while slightly trailing the Earth with an orbital period of about 372.5 days. With this orbit the spacecraft should be able to avoid having its view blocked by the Earth, Moon, or Sun. The reason this is important is because of the methods with which the spacecraft will search for these potentially habitable planets.

The Kepler spacecraft will search for Earth-like planets using a technique known as the Transit Method of Detecting Extrasolar Planets. A transit occurs when a planet crosses in front of its host star as viewed by an observer. These transits dim the brightness of a star which allow for the detection of extrasolar planets. This change in brightness is very difficult to detect by terrestrial planets, such as Earth, because they only dim their host star by 100 parts per million, lasting only 2 to 16 hours. In order for an extrasolar transit to be observed from our solar system, the orbit must be viewed edge on. The probability of observing such a planet is less than 1%. To increase the chances of observing a transiting terrestrial planet, the Kepler spacecraft will observe 100,000 of our neighboring stars. Because any planet in the habitable zone will require an orbit close to that of one Earth year, Kepler will need to observe any transits discovered amongst these 100,000 stars for at least 3.5 years to determine if the transit is periodic enough to be a planet.

The Kepler Mission may not be able to directly determine whether or not we are alone in the universe, but it will be able to tell us if we have neighboring planetary systems, containing planets, capable of sustaining life. When compared to all the stars in the universe, even one discovery amongst the relatively small sample space of 100,000 stars will be significant enough for us to rethink our meaning and place in the universe.

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A Mirror of Our Creation

Friday, October 31st, 2008 by Evan Finnes

In a planetary system only 10 light years away, Spitzer has discovered that there is much more to Epsilon Eridani besides a great setting for an Asimov novel. Epsilon Eridani is the star at the center of the planetary system closest to home. This Star is relatively young, perhaps less than a billion years old, and has a mass which is about .85 times the mass of the sun. As far as atomic creation goes, this sun is relatively inactive, producing not much more than Helium.

This system has been a source of great discovery; in the past it has been found to host two planets, an asteroid belt which orbits the star at a similar distance to which our asteroid belt orbits the Sun, and distant ring of dust and ice which is very similar to our Kuiper Belt. Recently, Spitzer observed that there is not just one, but two asteroid belts orbiting the not so distant star. What makes this discovery so exciting is the idea that by observing this system, we are basically looking back in history to observe our own creation.

According to the Nebular Hypothesis, solar systems are formed because massive clouds of dust and helium condense to form stars. This condensing occurs because these clouds are gravitationally unstable, so they collapse inwards into smaller clumps which accumulate to form a star, such as our Sun or Epsilon Eridani. As this star forms it sheds a disk of matter which over time begins to accumulate and form protoplanets. Although planetary formation is not well understood, it is thought by some that because of the gravitational pull of the forming star, the dense accumulating rock stays closer to and orbits the star, while the less dense gasses are able to stay further from the star in their orbit. This could be why the terrestrial planets such as Earth are closer to the Sun, while the gas giants such as Jupiter form much further out (of course there have been recent discoveries of gas giants closer to the sun than even Mercury).

Some theorize that the asteroid belts in our solar system are the result of the tidal forces produced by the gravitational pulls of the Sun and the gas giants. These tidal forces keep the rocks in the asteroid belt from coalescing to form protoplanets. The gas giants might also have another roll in solar system formation. It is possible that that the gas giants sweep out asteroids as they rotate the star, protecting the terrestrial planets from catastrophic impacts. However, some scientists also believe that the gas giants could act has a gravitational sling shot which could attract and hurl asteroids into the inner solar system.

One of the planets discovered to orbit Epsilon Eridani is located about 3.5 Au’s from the star, just outside of the range of the newly discovered asteroid belt. This is the first time a planetary system has been discovered to have an arrangement which is comparable to Jupiter and our asteroid belt.

Does this discovery prove that our solar system was formed with agreement to the Nebular Hypotheses? No, but it is defiantly worth observing this relatively young star system to see if its evolution correlates at all with any of our ideas. Who knows, maybe we could even watch as the formation of an Earthlike planet unfolds before our very eyes.

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