The interior structure of Venus - Essay Example

?Sur Lecturer What? is? the? interior? structure? of ?Venus??? Does? Venus? have? a? molten? outer? core??? If? so,?how? big ?is ?it?Mission objectives As a planetary scientist, my paper seeks to design and propose a robotic space mission by exploring the possible answers and explanations to the identified questions about Venus planet. What constitutes the interior structure of Venus as well as the question as to whether the outer core of Venus is molten or not will form the basis of my mission concerning our solar system. Justification The fact that Venus is arguably similar to earth in its internal composition and structure make me eager to embark on my mission of exploring the planet Venus. This will give more insight to the already existing assumption and explanations about Venus as planet similar to Earth and therefore my mission is worth being funded. Background The interior of Venus perhaps is similar to interior of the Earth. Venus, like the Earth, is a terrestrial planet that is made of metal and rock. It perhaps has a metallic core that is partly molten, a crust and a rocky mantle. But regardless of the planets' similarities, Venus`s magnetic field is very weaker than on Earth's. Interior structure of Venus is therefore slightly different from the Earth`s. The reasons for this are partly to do with their core and partly it could basically have to do with their motion. Venus rotates very slowly and it takes more than 243 of Earth days to rotate once on its axis. This is even longer compared to the time Venus takes to orbit the Sun which is about 225 Earth days. This may be mainly the reason Venus doesn't contain a magnetic field like majority of the other planets. The core might also be absolutely solid, or could not even exist in the first place. The different terrain of Venus, consisting of volcanoes, craters, mountains, and lava flows, hint that the Venus was once and possibly still is, geologically active. But central questions about interior of the planet Venus remain, like thickness of the lithosphere. Because Venus created at the same time the Earth was formed, in the same solar system`s general region, and the two planet are very similar in size (Earth = 6378 km and Venus = 6052km) and density (Earth = 5.24 g/cm3 and Venus = 5.52), it is alleged that Venus has interior structure quite alike to the Earth's (Milone & William,54-57). Venus`s average density which is 5.25g/cm3 reveals that Venus, just like the Earth, must be composed of silicate rocks as well as be a differentiated planet. sustaining data for internal models hails from gravity as well as magnetic field readings from Venera, Pioneer Venus together with Magellan spacecraft. It is thought that Venus created a differentiated core made up of the heaviest elements for instance iron sinking to middle of the Venus. It`s however, not known if the core of Venus has yet solidified to the same level as of the Earth's core. Despite the proportions of core, crust and mantle being similar to Earth, the surface revelation is that there are none of moving 'plates' as there exist on Earth that can mean. This shows that either the crust is a bit thicker and planet cannot form, or Venus mantle is not convecting a fast way as Earth's mantle so as to stir the plates around. Previous mission Very less is well-known concerning the interior of Venus compared to what is known about its atmosphere and surface. Previous mission to the space and exploration of the other planets focused more on their surface and atmosphere. These missions were of atmospheric probe and orbiters types. However, my mission is quite different as it explores the interior of Venus, I mission that is hardly undertaken by scientists. Venus is much like the Earth in density and in overall size and because it most probably accreted from similar materials, as planetary scientist, I expect that Venus formed at least a crudely alike internal state. Therefore, it almost certainly has mantle of dense rock, a core of metal, as well as the crust of lesser dense rock. The core, just like that of Earth, is in all probability composed primarily of nickel and iron. However, the lower density of Venus somehow reveals that its core may also consist of some other less-dense material for instance sulfur. Since intrinsic magnetic field has not been detected for Venus planet, there is no direct proof for a metallic core that is there for Earth. Calculations of the internal structure of Venus propose that the external boundary of the core is situated a little more than 3,000 kilometers from the centre of Venus (McFadden, Lucy-Ann, Paul & Johnson, 37-40). My mission will provide information the interior of Venus and therefore build up on the already accomplished atmospheric probe mission and orbiter who had already given an insight on the surface and atmosphere of Venus. Above the core but below the crust exist the Venus’s mantle which make up the bulk of Venus`s volume. Temperatures inside the mantle are probably similar to those in the mantle of Earth despite the soaring surface temperatures in Venus. Although a planetary mantle is consisting of solid rock, material in there can gradually creep or flow, like a glacial ice does. This allows sweeping convective movement to take place. Convection is definitely a huge equalizer of temperatures of planetary interiors. Heat within Venus is considered to be originating from the decay of existing natural radioactive materials, a way similar to heat creation within Earth (Karato & Shun-ichiro, 17-20). This heat is transferred to the surface through convection. Were it that the temperatures deep inside Venus were significantly higher than those inside Earth, then the viscosity of rocks inside the mantle would fall sharply, thereby speeding convection and eliminating the heat more quickly. Therefore, Earth and Venus` deep interiors are not likely to differ considerably in temperature. As hinted above, the Venusian`s crust composition is thought to be dominated by basalt. Gravity data propose to me that the crust`s thickness is fairly consistent over much of Venus, with typical values of possibly 20–50 km. Possible exclusion are the highland of tessera, where the crust might be considerably thicker. Convective motions in Venus’s mantle can make materials around the surface to experience stress. Moreover, movement in the Venusian mantle might be greatly responsible for tectonic deformation seen in radar images. Gravity field on Venus is found to correlate further with topography over the broad regional scales compared to when it is on Earth, that is large regions with higher topography compared to the mean elevation on the planet, Venus also double as the regions with measured gravity higher than average (Elkins-Tanton & Linda, 23-25). This means that huge fraction of the increased mass linked to the elevated topography is actually not offset by a replacement deficit of mass in underlying crust which supports it. That is the low-density roots as it`s literarily called on Earth. Question on whether outer core of Venus is solid or liquid remains open. Calculations on Venus` inertial moments are impossible since it rotates too gradually. Previous missions never saw any sign of tectonics and so the heat transfer method on Venus is possibly very different to Earth. The outer core is perhaps surrounded by silicate mantle that is about 3000km thick and with hot enough outer layers to aggravate a partial state of combination between the materials. The crust`s thickness, as determined by viscous relaxation models and tectonic deformation, is approximated to range between 10 and 30 km. Analyses by various Venera probes evidenced that the outer material of Venus is alike to Earth basalt and granite (silicate rocks with metals). The continental plates system is not more complex than on Earth and plastic rocks suck up most of the continental drift effects. This proposes that Venus actually has a 2900km radius core that has two parts: the outer core made of liquid nickel and iron and an inner core made of solid nickel and iron. It’s thought that the magnetic field of Earth is generated through convection of liquid inside Earth’s core. Venus doesn’t possess a planetary magnetic field and therefore it has a solid inner core. However, outer core of Venus is composed of iron-nickel and unlike it`s inner core, it`s not subjected to enough pressure that can make it a solid. Venus therefore has a liquid external core but only an exceptionally faint magnetic field, perhaps because Venus’ rotation rate, that drives convection in fluid, is tremendously slow or perhaps there isn’t sufficient temperature gradient between outer core and inner core to make this convection happen. It’s thought that global resurfacing event which occurred over 300 million years ago may have a bearing in this (De, Pater & Jack 43-47). The complete surface of Venus got resurfaced, closing down plate tectonics. This may have cause minimized heat flux through crust and so trapping the heat within the planet. Without the huge heat difference, there’s minimal heat convection, and by extension no magnetic field hailing from core of Venus. Venus planet has a diameter of 12,103,006 km with the radius of its outer core being 30 percent of its diameter (Bertotti, Bruno, Paolo & David, 23-45) Mission plan Despite the absence of seismological data, I will use a proposed model of interior structure that is based on gravimetric data. My spacecraft will carry and place seismometers so as to search for 'earthquakes' which can help me probe the planet's interior. The motion inside Venus will be measure with my seismometer. I will also have on board clinometers which I will used to measure elevations and slopes with the aim of determining what sorts of activities happens insides Venus. Work Cited Bertotti, Bruno, Paolo Farinella, and David Vokrouhlicky?. Physics of the Solar System:Dynamics and Evolution, Space Physics, and Spacetime Structure. Dordrecht [u.a.: Kluwer Acad. Publ, 2003. Print. De, Pater I, and Jack J. Lissauer. Planetary Sciences. New York: Cambridge University Press, 2010. Print. Elkins-Tanton, Linda T. The Sun, Mercury, and Venus. New York: Chelsea House, 2006. Internet resource. Karato, Shun-ichiro. The Dynamic Structure of the Deep Earth: An Interdisciplinary Approach. Princeton: Princeton Univ. Press, 2003. Print McFadden, Lucy-Ann A, Paul R. Weissman, and T V. Johnson. Encyclopedia of the Solar System. Amsterdam: Academic, 2007. Internet resource. Milone, E F, and William J. F. Wilson. Solar System Astrophysics. New York: Springer, 2008. Print. . Read More