EAP ESSAY The effects of microgravity on bones

During the Apollo era, the idea of humans exploring space was first envisioned (Buckey, 2006). The curiosity for what was “out there” needed to be satisfied and thus began the era of human space exploration. Scientists have been anxious to widen their knowledge about outer space for ages and because of modern technology those wishes were made possible. First NASA started with the lunar mission and now they are gradually leading up to a space mission to Mars. A mission that will take over 30 months. 18 of which astronauts will actually spent on-site (NASA, 2008). This mission, even though it is an imperative mission that will allow us to know more about the universe, will bring great risks to the astronauts making this journey. A number one priority is their health. The problems astronauts encounter are caused by being in a weightlessness mode for such a long time. One of the major problems is the loss of bone mass. Scientists are working on solutions on how to minimise the impact of bone loss in space for when astronauts return to a weight-bearing mode such as we have on Earth. The major risks astronauts could encounter when they are back in our world are bone disorders such as osteoporosis.

The obstacles that astronauts face are not to be treated lightly. How they are handled by astronauts may play a great deal in their survival. However, not every challenge can be beaten completely; one of which is bone loss. This phenomenon is something that is inevitable during space-flight. What is to be understood about bones is that they are not fixed structures; they are capable of change. Bones are constantly adapting to their surroundings and the marks that they leave on bones are permanent (NASA Science, 2011). Therefore, when astronauts are in the microgravity environment of space, this will have an impact on their skeleton. Specifically on their bone mineral density which will decline by 1% to 2% every month they spend in space (Canadian Space Agency, 2006 and NASA Science, 2011). Astronauts develop a very low bone density during their time in space; this is known as osteopenia (MedlinePlus, 2011). Besides having a low bone density, there is another problem that comes with weightlessness: an acceleration of bone resorption. Bones exists out of three different cells: osteoblasts, osteocytes and osteoclasts. Osteoclasts are the cells that are of importance in the process of bone resorption for they break down bone and release the minerals into the blood stream. This is their sole function (Teitelbaum, 2000). Bone resorption is a process that occurs within every human being, but by being in space the process gets sped up, leaving the astronauts with a higher risk of developing health problems at a young age.

The consequences of bone loss will most likely be found when astronauts return to earth and have to use the full strength of their bodies again. Their bones have suffered a severe loss and the likelihood of fracturing them is higher than before the mission. Even worse, the chances of having osteoporosis or other severe bone disorders at a young age are much higher after spending a long amount of time in space (Teitelbaum, 2000). “Osteoporosis is a disease that causes bones to lose density and strength” (CSA, 2006). This disease occurs when bone resorption exceeds the process of bone formation which means that the bones are being broken down before they have the chance to be formed. This is what happens to astronauts. Osteoporosis is not only a problem to returning astronauts; it is also a problem many people on Earth face. Especially postmenopausal women are prone to this disease, (NASA Science, 2011) their bone mass will decrease about 2 to 3% per decade. However, this is hardly comparable to the bone mass astronauts will lose; which can vary from 0 up to 20% (White and Averner, 2001).

In the battle against these disorders, scientists hope to find a method to prevent the decrease in bone mass in space. Astronauts already tried various exercise regimens both in space and on Earth; however, this method has not been proven effective. The same applies for a dietary filled with calcium and vitamin D supplements. Nonetheless, a combination of both resistive exercise and a pharmalogical agent has the possibility to decrease the loss of bone mass in space (White and Averner 2001). This pharmalogical agent should include bisphosphonates as it is proven that they limit the loss of bones where the process of bone resorption increases (White and Averner, 2001; NASA, 2008).

Scientists are mostly looking at hormonal countermeasures. The first hormonal countermeasure scientists have found is growth hormone; it is shown to increase bone mass, however it has only been proven effective when injected into young men. The problem with this solution is that it has only been tested on Earth, so the outcome in space is still unknown. Second, scientists found a hormone called IGF-1 (an insulinlike growth hormone) that has a very promising outlook in increasing bone formation in space: IGF-1 was inserted into rats that flew for ten days on the Space Shuttle and after this, an increase of bone mass in the humerus (the bone in the upper arm) was observed. However, it is questioned whether or not this is in fact applicable to humans (Buckey, 2006). A third probable hormonal solution is injecting parathyroid hormone, but doing this has to be done with care for this hormone has a very complex influence on the skeleton; injecting it can lead to both the increase and decrease of bone loss. With a chronic increase of this hormone more bone resorption will take place, however parathyroid hormone also has anabolic functions which will lead to the increase of bone mass. So, there are both positive and negative side effects to this specific hormone treatment (Buckey, 2006).

In short, bone loss is a process that cannot be avoided during a long space mission such as the mission to Mars; even afterwards the consequences can be severe. Scientists are doing everything they can to find a solution. In my research I found several hormonal countermeasures against bone loss in space, although there are also dietary and physical probable solutions, I found the hormonal countermeasures the ones to be the most promising; especially the IGF-1 treatment for there has been some evidence that it actually increased bone mass after space-flight. Hopefully in the future, a proper solution will be found and astronauts can have a healthy life even after their adventures in space.

Bibliography

Buckley, J.C., 2006, Space Physiology. (e-book) Cary: Oxford University Press. Available through: Anglia Ruskin University Library website <http://libweb.anglia.ac.uk>

Canadian Space Agency, 2006, Space Medicine. (online) Available at: <http://www.asc-csa.gc.ca/eng/astronauts/osm_bones.asp> (Accessed 3 December 2011)

MedlinePlus, 2011, Osteoporosis. (online)
< http://www.nlm.nih.gov/medlineplus/osteoporosis.html > (Accessed 6 December 2011)

NASA, 2008, Missions. (online) Available at: <http://bioastroroadmap.nasa.gov/User/mission.jsp?filterMissions=3 > (Accessed 3 December 2011)

NASA Science, 2011, Space Bones. (online) Available at: < http://science.nasa.gov/science-news/science-at-nasa/2001/ast01oct_1/> (Accessed 5 December 2011)

Teitelbaum, S.L., 2000, Bone Resorption by Osteoclasts, Science, (online) Available at: <http://www.sciencemag.org/content/289/5484/1504.short> (Accessed 8 December 2011)

White, R.J. and Averner, M., 2001, Humans in Space. Nature, vol. 409, p. 1116

Crewed Mission to Mars- EAP Essay

Since ancient times man has looked with wonder upon the skies looking anxiously for answers to very complex problems (Hudgins, 2011). Mars has always been in the centre of all that human fascination impelling us to redefine dreams and aspirations and make them real. This timeless passion does not seem to fade away any time soon as we are currently entrepreneuring an astonishing interplanetary journey to the “red planet”. Many scientific, technological and philosophical issues will rise with this ambitious undertaking, declares Williams (2005), but they can be overcome with will and commitment and by using all our skills and abilities. Green (2011) reported that the answers we will hopefully obtain in Mars have the potential of improving the lives’ of billions and will propel a new era of discoveries and accomplishments allowing us to grasp more knowledge about the Earth itself. The actual mission retains more questions than answers as many issues must be addressed, however the solution that will enable humans to start an planetary space exploration and perhaps human settlement are out there. The most difficult challenge by far is fuel and energy manufacturing since astronauts cannot possibly take with them all their energy needs due to added weight. Much data has to be considered and much more research has to be done before facing certain logistic barriers which range between “spaceship trajectories, gravitational forces, and micro meteorite impacts” states Allan (2011), and also transportation, crew safety, mission equipment, food and water supply availability, gravity deprival, harmful radiation effects, to name a few.

Energy is most certainly one of the big questions to solve because without power the Mars expedition could not even start, this idea is correlated by ESA (2007) and Mankins (n.d.). Without which the spacecraft would be unable to achieve flight and rise into the skies. Moreover, energy is always necessary for propulsion, assuring all of its electronic and mechanic instruments are working like a life support syste such as the engines and informatics systems, as stated by Marks (2008). Due to the significant distance between Mars and Earth, the mission will have many high risks and therefore it will be more expensive than the trips to the Moon. Huge amounts of supplies and fuel will be needed to carry out for this round trip of two to three years. The escape velocity of the “Red Planet” is approximately 5km/s, according to NASA (2010), which is reasonably high. This will soar the energy consumption and the costs of exploring and colonising the planet.

Fortunately, due to this a wide range of solutions can be considered nevertheless with some drawbacks. One current proposal is named “Mars Direct”, created by Zubrin and Baker (1990), it is a scheme considered to be both practicable and cost-effective for a crewed mission to Mars which can be conducted with current technology. The basis differs from the current project which is sending a single spaceship with everything astronauts need for a return trip. The basis of this project is to send in several un-manned flights with supplies that the space pioneers would require in both the first trip and the following ones. This plan is more energy efficient and would allow explorers to have everything at hand to start settlements in that inhospitable environment and do precious scientific research work. This task will probably be achieved by using several small nuclear reactors, that as a bi-product produce heat, which would be extremely valuable for a Mars colony and also hydrogen, which can be created through electrolysis methane and oxygen claims (Cooper, et al., 2009) and (Kleiner,2003) . Since this kind of fuel is very dense it will be cheap to transport from Earth.

Current batteries even if recharged do not have a lasting life span, so experts like Gerstenmaier (2011) believe that it would be useful to tap into the resources of Mars’ moons, as they contain rocket propellant. As refuelling outposts they should be economically viable and could potentially pay for the colonisation of Mars. On the other hand a tremendous amount of energy would be spent, in terms of monetary and natural resources before gaining anything from it.

Another far stretched idea envisioned by Quine (2008) is a space elevator, although this is practical it is highly unfeasible. The idea is that the orbits of both Mars and the Earth would allow a cable to be connected between the two planets allowing easier access to goods at either end.

Above all we must find a solution which is technologically achievable. Chemical rockets are today’s reality, but they may be replaced by nuclear power thrusters or ion drives and solar sails which will shorten the trip by several weeks, according to Perminov (2010). This will allow better communication making it easier to send fuel to the Mars colony as they are unable to produce it by themselves.

Keeping in mind all these solutions, in my opinion the best candidates capable of withstanding the space explorers energy needs is solar and wind power, which are undoubtedly unlimited. This will not only decrease the transportation costs but also allow astronauts to be independent and self-sustainable. Although Mars is further from the Sun its atmosphere is thinner and therefore it still receives considerable amounts of energy making this option a feasible one according to ROSCOSMOS (2010). Although this may be true, dust storms are still part of Mars’ reality, making it difficult or even impossible to gather energy. Therefore I propose a “plan B”; wind power. Since these storms may contain 150 km/h winds, if tapped properly it may complement solar power, this idea was supported by Knight (2001) and Hill (n.d.).

All things considered it may be a good idea instead of producing ever increased amounts of power, considering lowering the astronauts energy needs (NASA, 2008) and heating requirements by simply using domes to naturally trap solar heat, as if they were greenhouses and by travelling using “a minimum energy trajectory” (Williams,2005).

Overall, if space colonisation comes true, Koroteev (2010), Mars is the first ideal choice as a space agency since it is the closest to Earth-like conditions as reported by Allan (2011) and supported by ESA (n.d), NASA (n,d) and ROSCOSMOS (n.d). Still it will be necessary to develop more complex studies, relating to all the necessary conditions to protect both equipment and the crews live’s. The continuous supply of energy is therefore a critical factor (Cole,n.d) because without power neither the mission objectives will be accomplished nor the astronauts will be able to resist such a voyage of inevitable dangers.

Reference Section

Allan,S., 2011. Why Mars inspires public and scientists alike.[online] (25 November 2011) Available at: http://news.uk.msn.com/blog/the-space-blog-blogpost.aspx?post=9b22dc98-67e9-47bb-8948-024ff74ad1ee&_nwpt=1 [Accessed 3 December 2011].

Barker,J.,2011. The search for Earth's twin. [online] (6 December 2011) Available at: http://news.uk.msn.com/blog/the-space-blog.aspx [Accessed 7 December].

Cooper,C., Hofstetter,W., Hoffman , J.A. and Crawley,E.F., 2009. Assessment of architectural options for surface power generation and energy storage on human Mars missions. [online] (14 November 2009) Available at: http://www.sciencedirect.com/science/article/pii/S0094576509004834 [Accessed 2 December 2011].

ESA, 2007. Rosetta successfully swings-by Mars – next target: Earth. [online] (5 February 2007] Available at: http://www.esa.int/esaMI/Rosetta/SEMWZ5CE8YE_0.html [Accessed 6 December 2011].

Green, J., 2011. Why UK science gets bang for its buck. [online] (18 November) Available at: http://news.uk.msn.com/blog/the-space-blog-blogpost.aspx?post=9b22dc98-67e9-47bb-8948-024ff74ad1ee&_nwpt=1 [Accessed 3 December 2011].

mg17823904.700-nuclear-rockets-could-help-land-man-on-mars.html [Accessed 30 November 2011].

Knight, W., 2001. Mars engulfed by global dust storm. [online] (12 October 2001) Available at: http://www.newscientist.com/article/dn1423-mars-engulfed-by-global-dust-storm.html [Accessed 1 December 2011].

Knovel., 2011. NASA Eyes Refuelling Stations In Space To Help Send Manned-Missions To The Moon, Mars. [online] (24 October 2011) Available at:http://why.knovel.com/all-engineering-news/973-nasa-eyes-refueling-stations-in-space-to-help-send-manned-missions-to-the-moon-mars.html (Accessed 7 December 2011).

Marks, P., 2008. Sun shines on future Mars colonies. [online] (17 November 2008) Available at: http://www.newscientist.com/article/mg20026826.100-sun-shines-on-future-mars-colonies.html [Accessed 29 November 2011].

Mars Society, 2011. Mars Direct. [online] (30 April 2011) Available at: http://www.marssociety.org/ (Accessed 2 December 2011).

NASA, 2002. What advances is power technology are required to send human and robotic explorers throughout the Solar System?.[online] (3 September 2002) Available at: http://science.nasa.gov/science-news/science-at-nasa/2002/03sept_spacepower/ [Accessed 30 November].

NASA, 2008. Dust Storm Cuts Energy Supply of NASA Mars Rover Spirit, [online] (10 November 2008) Available at: http://www.nasa.gov/mission_pages/mer/news/mer-20081110.html [Accessed 4 December].

Parabolic Arc, 2010. Perminov: Mars Trips Could Take 2-4 Months With Nuclear Propulsion. [online] (30 September 2010) Available at: http://www.parabolicarc.com/2010/09/30/perminov-mars-trips-24-months-nuclear-propulsion/ [Accessed 8 December 2011].

Quine, M.Q., United States Patent and Trademark Office.,2008. Space Elevator. U.S. Boston. PAT.12/524,130

ROSCOSMOS, 2010. Academician Koroteev: Missions to Mars are to Become Real in the Nearest Future. [online] (26 May 2010) Available at: http://www.federalspace.ru/main.php?id=2&nid=9500&lang=en [Accessed 5 December 2011].

ROSCOSMOS, 2010. New Advanced Propulsion Systems to Make Mission to Mars in 2-3 Months Feasible – Anatoly Perminov. [online] (30 September 2010) Available at: http://www.federalspace.ru/main.php?id=2&nid=10461&hl=new+advanced+propulsion+systems+to+make+mission+to+mars+in+2-3+months+feasible+%96+anatoly+perminov [Accessed 5 December 2011].

Williams, D., 2005. A crewed mission to Mars. [online] (25 April 2005) Available at: http://nssdc.gsfc.nasa.gov/planetary/mars/marsprof.html (Accessed 27 November 2011).

Williams, D., 2010. Mars Fact Sheet.[online] (17 November 2010) Available at: http://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html [Accessed 5 December 2011].

EAP

Sending a crewed mission to Mars?

Observing the dark night sky, wondering about the Universe, has been, throuhout History, one of Humankind’s favourite activities. Driven by curiosity, human beings have made some huge discoveries. Nevertheless, their thirst for knowledge will never be satisfied. After several centuries dreaming about crossing the boundaries that Earth had imposed on them, men finally managed to send a human to orbit Earth in 1961, four years after the first artificial satellite Sputnik 1 had been launched (The Aerospace Corporation, 2005). However, this was not enough. In their constant struggle to go the distance and conquer what hasn’t been conquered yet, humans persued their dream of going further and reaching the moon. After several unmanned mission and some disasters, on the 20th July 1969, Neil Armstrong and Edwin Aldrin landed on the surface of the moon (Wilson and Dunbar, 2010). Nonetheless, the possibility of an extraterrestial life, the reason why scientists crave exploring the Universe, made them want to go further. And Mars, the red planet, being close (Starobin and McClare, 2004) and the most similar one to Earth, was the best candidate for hosting life (Naderi, 2003). Many missions have been sent to Mars over the last five decades (Garber, 2009), but all of them, uncrewed due to the huge amount of challenges that sending astronauts to Mars compound (Rapp, 2006). A part from mechanics and engineering problems that can arise, one of the biggest inconvenients of a manned mission to the red planet is the issue of the radiation (Ingham, 2007).

Galactic cosmic radiation (GCR) and Solar particle events (SPE) are the two major provenances of radiation in space (Rapp, 2006). A continuous emission of very high energy is what characterises GCR. This kind of radiation harms directly the tissues and its intensity depends on the atomic number of the particle (Buckey, 2006). It is very difficult to shield against this type of radiation (Buckey, 2006); by contrast, a spacecraft can be enough to protect a crew from SPE radiation. SPE, composed mainly by protons, is originated during solar storms which release a huge amount of energy that if ever reaches the Earth will probably damage satellites and influence communication systems (Buckey, 2006). These two sources of radiation may cause severe problems to the astronauts that adventure themselves through space.

Among several body parts that are affected by these types of radiation, the Central Nervous System (CNS) is one of the most important ones, even though the risk of developing cataracts or reducing fertility are also problems that need being tackled (Buckey, 2006). According to Cucinotta, Wang and Huff (2009), there are documents proving that acute and late risks to the CNS from GCR and SPE are an issue to take into consideration when thinking about sending men to space for long periods of time. Nevertheless, one of the major concerns about being exposed to radiation is the fact that it can trigger the development of cancerigenous cells (Buckey, 2006). Ingham (2007) refers back to a NASA estimate pointing out that travelling to Mars and back would increase the risk of developing fatal cancer in 40% in a healthy 40-year-old man. However, when submitted to radiation, some cells are able to recover whilst others, who are not able to repair the damages, die. Even though it could be a good sign for dead cells are not cancerigenous ones, if a large amount of cells in the same tissue die, the function that they are supposed to fulfill faces failure (Cucinotta et al., 2005).

Although it is certain that the exposure to space radiation for a large period of time affects astronauts in a bad way, the biological effects from such exposure are not clear yet for they may differ from individual to individual (Rapp, 2006). And that is the main problem. Two years is the amount of time needed for a round-trip Mars mission, according to Shiga (2009). The author also states that in a quarter of that period, astronauts would have already transpassed “NASA’s maximum recommended doses of space radiation” (Shiga, 2009). But the truth is that scientist have only been able to narrow the level of uncertainty in predictions to 10-15% (NRC, 2008), which is still higher than it should be in order to savely send crewed missions to Mars.

The National Research Council (2008) states that there are three main ways to reduce the radiation doses: increasing the distance from the radiation source, decreasing the time of exposure and using shields. The first two are not possible for the moment in a mission to Mars, for it is needed quite a long time to reach the red planet with the technology that space organisations have available. As for the shielding solution, even though the spacecraft is usually enough to shield the astronauts against SPE, if the storm is stronger than predicted, the doses of radiation emited could damage the crew of the spacecraft (Buckey, 2006). What is more, these solar storms can begin on both “sides” so in a Mars mission the crew would have to rely on the monotoring to provide them advance warning for they would be far away from Earth (Buckey, 2006). Although the NRC (2008) suggests that HDPE, a type of shield, is, indeed, capable of providing the necessary amount of protection against most types of radiation, Buckey (2006) affirms that it is very complicated to shield against GCR due to the “high energies of the individual particles.” Also, the NRC (2008) stresses the importance of predicting space and solar weather in order to prevent great catastophs. For instance, a portable shielding (blanket) for temporary SPE releases could be used effectively if it was possible to predict major SPE emissions (CNR, 2008). Since there is not much information about the precise effects of radiation on humans, McCarthy (1997) proposes another solution; that more money is invested on research in order to gather enough data so that astronauts can be protected in a more effective way.

Sending a crewed space-craft to Mars is, afterall, a very complicated decision. There are several inconvenients and most of them very dangerous. One of the biggest problem that these missions have is the lack of precise information about the effects of radiation on human beings. However, considering the previously presented possible solutions, more effective shielding pannels could be studied and developped but it could, also, be helpful to postpone the dream of landing into the red planet a few decades and research more on the biological effects of the long exposure to space radiation.

REFERENCES

Buckey, J., 2006. Space Physiology. New York: Oxford University Press, 2006.

Cucinotta, F.A., Kim, M-H. Y., and Ren, L., 2005. Managing Lunar and Mars Mission Radiation Risks. Available at: http://www.lpi.usra.edu/lunar/documents/NASA%20TP-2005-213164-pt1.pdf

(Accessed 4 December 2011)

Cucinotta, F.A., Wang, H. and Huff, J.L., 2009. Risk of Acute or Late Central Nervous System Effects from Radiation Exposure. Human Health and Performance Risks of Space Exploration Missions (NASA Documents), (online) Available at: http://spaceradiation.usra.edu/references/Ch6CNS.pdf (Accessed 7 December 2011)

Garber, S., 2009. A Chronology of Mars Exploration, Available at: http://history.nasa.gov/marschro.htm (Accessed 7 December 2011)

Ingham, R., 2007. Space Radiation Could Be A Mars Mission-Killer, Space Travel (online), Available at: http://www.space-travel.com/reports/Space_Radiation_Could_Be_A_Mars_Mission_Killer_999.html (Accessed 5 December 2011)

McCarthy, M.,1997. Radiation risk could imperil Mars mission. Lancet, Vol. 349 Issue 9045, p.106

Naderi, F., 2003. The Challenges of Landing on Mars. Available at: http://www.nasa.gov/vision/universe/solarsystem/mars_challenges.html (Accessed 7 December 2011)

NRC, 2008. Managing Space Radiation Risk in the New Era of Space Exploration. Washington, DC: National Academy Press.

Rapp, D., 2009. The challenges of manned Mars exploration, The Space Review, (online) Available at: http://www.thespacereview.com/article/602/1 (Accessed 5 December 2011)

Shiga, D., 2009. Proposed Mars trip would exceed NASA's radiation limits. New Scientist,Vol. 203 Issue 2726, p.11

Starobin, M. and McClare, M., 2004. NASA Goddard Space Flight Center, Available at: http://www.nasa.gov/vision/earth/environment/Sibling_Rivalry.html (Accessed 7 December 2011)

The Aerospace Corporation, 2005. Available at: http://www.aero.org/education/primers/space/Space-Primer.pdf (Accessed 4 December 2011)

Wilson, J. and Dunbar, B., 2009. July 20, 1969: One Giant Leap For Mankind, NASA, (online) Available at: http://www.nasa.gov/mission_pages/apollo/apollo11_40th.html (Accessed 7 December 2011)

University Foundation Year – Science Class

THE LAST FRONTIER

A Voyage to Mars

“Hesper - Venus - were we native to that splendor or in Mars,
We should see the globe we groan in, fairest of their evening stars.
Could we dream of wars and carnage, craft and madness, lust and spite,
Roaring London, raving Paris, in that point of peaceful light?
Might we not in glancing heavenward on a star so silver-fair,
Yearn, and clasp the hands and murmur, 'Would to God that we were there'?”

( Alfred Lord Tennyson )

Humankind has always been fascinated by space voyages; exploring new planets and systems may allow us to discover new species or new materials that we are not aware of, or maybe to find a new planet suitable for human colonisation.
About the latter, scientists attention had immediately been caught by the “Red Planet”, better known as Mars, the closest planet to Earth, moving away from the sun. A challenge for the next decades may be the achievement of Mars by a manned spaceship, but the difficulties involved should not be undervalued.
The fuel consumption required for a such long voyage and back is tremendously high, so that there is a serious risk of the spacecraft failing the mission, in terms of both first reaching Mars and returning due to the lack of fuel onboard; researchers are continuously pushed to find new solutions, in order to alloe the journey to Mars be possible.
Also psychological and physiological facts, not directly involved with the fuel problem, but taking them an active role during the cruise, must be faced with care too.

‘The minimum distance between Mars and Earth is when Earth is at farthest point from the Sun (aphelion) and Mars is at its closest to the Sun (perihelion), which is 54.6 million kilometres (Coffey,2008). The writer also argues that on the opposite end of the scale, Mars and Earth can be 401 million kilometers apart: mankind have experienced not even a quarter of that. Furthermore, it is also important to pinpoint that the reach of the minimum distance is a rare fact, that happens every 26 months (Coffey, 2008), implying the launch to be carried out in a certain period, called ‘launch window’. Consequently, once it arrives, astronauts will have to wait other 26 months.

In addition, another critical factor are the implications of the whole fuel consumption used in the “launch phase”, when 1,607,185 tons of weight (NASA, 2011) have to overcome the Earth’s atmosphere, contrasting the gravity and pushing the shuttle up to 528 kilometers of altitude, where G force can not affect it.
According to NASA (2011), Space Shuttle is designed to travel in low-Earth orbit and it does not carry enough propellant to travel to the Moon; questioning then the possibility of actually reaching Mars.

The most common belief is that the shortest way to Mars is obtained by travelling directly towards it; actually that has found to be untrue (University of WA, n.d.).
Because the trend of every object to follow an orbit in the space, being attracted by the Gravity Force from every ‘size-relevant’ celestial body, the Shuttle, just after passing the atmosphere, would be caught by other gravitational fields, joining consequently other orbits and consequently travelling following curved trajectories. (Basics of Space Flight, 2010).

According to Pendick (2009), travel to Mars will include three steps. Firstly, propelling the space-ship out of the Earth's gravity, secondly, accelerating on a trajectory to Mars and thirdly, descending into Mars' gravity and landing safely on the surface; but it is not as easy as it sounds.
Travel in which hundreds of millions of miles are traversed in fact, requires a tremendous amount of fuel.

A solution may came out from the so called ‘Mars Direct plan’(The Mars Society, n.d. ), developed by a physicist named Dr. Robert Zubrin, who claimed that the conquest of Mars may be possible by refueling the spaceship only for the outward journey, then making use of the Martian atmosphere to generate rocket fuel for the return, extracting water from the Martian soil and eventually using the abundant mineral resources of the Red Planet, arguing that this process will drastically lower the amount of material launched from Earth.

The idea is to send first a Cargo-ship called ERV (Earth Return Vehicle), which contains an ‘ISRU plant’, that will automatically, thanks to automated ‘Rovers’(a sort of space cars) display itself in order to start the rocket fuel production process; the ERV, as suggested by its name, will also be the module that, once unloaded its cargo payload, will carry home the astronauts after 26 months.

In agreement with Pendick (2009), the process of fuel manufacturing will be possible due to an automated chemical processing plant, a nuclear electric generator, and liquid hydrogen. The ISRU plant then combines the feedstock with carbon dioxide from the martian atmosphere to produce methane and oxygen for rocket fuel.
The manned spaceship will be launched towards Mars 26 months after the ERV launch, so that, once arrived, the astronauts will find their Earth Return Vehicle ready for their return.

Although ‘Mars direct’ seems to be a perfect solution, the difficulties and problems emerged ‘by themselves’.
First, Nicholson-Hutt (2004) suggests to be aware of about psychological problems, questioning herself about how can the crew avoid the inevitable tensions of close confines and, then finding a solution in which, thanks to a careful planning these problems can be lessened or avoided altoghether. Second, physiological problems also must not be undervalued; weightlessness lusting for several months is supposed to be at the base of many health problems, muscular dystrophy and ‘space anemia’, maybe possible to overcome by using a rotating space module, so that it will be possible to reproduce artificial gravity in space (Columbia Electronic Encyclopedia, 6^th Edition, 2011).
After all, ‘Radiations may be the biggest hurdle to human exploration beyond low-Earth orbit’(Shiga,2009). Moreover the author argues that for journeys outside Earth's magnetic field, astronauts could exceed ‘safety limit’ in less than 200 days.

Finally, as argued by Augustine Committee Review (2009), exploring the moon first would be a solution that could help us in developing operational skills and technology for landing on, launching from and working on a planetary surface, so that we might acquire the necessary knowledge in order to, maybe one day, achieve the conquest of Mars.

As far as I am concerned, the best solution might be the development of our operational skills, also practising in space manoeuvre on the lunar surface, so that in the next decades we will be ready to face a such challenging achievement, ironically considering that just a century ago reaching the moon would have been considered a foolish and impossible adventure.

In conclusion, despite ‘Mars-direct’ plan was developed in 1990, it still is the most reliable project for the most challenging achievement ever, especially for what concerns the fuel consumption. Regrettably, the mission includes also many problems, ranging from astronaut’s psychology and space medicine, where the hazards of a long space cruise are critically examined, to the problems concerning the technical and practical aspect.

Biobliography:

· Augustine Committee, 2009., Seeking a Human Spaceflight Programme worthy of a Great Nation, [pdf] Washington, DC: NASA: Available at: [http://www.nasa.gov/offices/hsf/home/index.html]

· Basics of Space Flight, 2010. Orbital Mechanics.[online] Available at:
[http://www.braeunig.us/space/orbmech.htm]

· Jerry Coffey, 2008. Distance from Earth to Mars. [online] Available at: [http://www.universetoday.com/14824/distance-from-earth-to-mars/]

· Columbia Electronic Encyclopedia, 6^th Edition, 2011. Space medicine. [online] Available at: [http://web.ebscohost.com/ehost/detail?vid=7&hid=122&sid=64ef6435-61f3-4dee-b0d8-4b934a5229c6%40sessionmgr113&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=afh&AN=39033261]

· NASA, 2011. Space Shuttle Program: Spanning 30 Years of Discovery [online] Available at: [http://www.nasa.gov/mission_pages/shuttle/main/index.html]

· Anna Nicholson-Hutt, 2004. Psychology and Space Travel: Planning for a Mars Mission. [online] Available at: [http://www.redcolony.com/art.php?id=0408300]

· Pendick, D., 2009. Next Step Mars, Astronomy, [online]. Available at: [http://web.ebscohost.com/ehost/detail?sid=8bdf62df-76bc-48a1-b114-fe30e7bc008e%40sessionmgr114&vid=1&hid=122&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=afh&AN=42638618]

· Shiga, D.,2009. Proposed Mars trip would exceed NASA's radiation limits, New Scientist, [online]. Available at: [http://web.ebscohost.com/ehost/detail?vid=9&hid=122&sid=64ef6435-61f3-4dee-b0d8-4b934a5229c6%40sessionmgr113&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=afh&AN=44605948]

· The Mars Society, n.d., Mars Direct. [online] Available at: [http://www.marssociety.org/home/about/mars-direct]

· University of WA, n.d., Gravity and Spacetime: Why do things fall? [pdf] Washington, DC: University of WA. Available at: [www.gravity.uwa.edu.au/docs/EGR/LectureDavid/Gravity%2520and%2520Space%2520Time.pdf+&hl=it&pid=bl&srcid=ADGEESgH_2Sx1yyIBBNKfbNizsZDIXttopxgZnw4N1LCrzatNQNAIbxtBVyVuqvoAfbXhRgdZHsZUtfx4sLquCFKMwzt8-pMighlpgTV3jCJhoPwlMlqOJmmchSUdk45s07GZRz7zWrm&sig=AHIEtbTS6RowvEmFcHDORvrXpXYKjfzG-Q]

UFY September Engineering 1 2012

Thursday, 22 November 2012

Useful language for line graphs

Serkan's list of useful words:

Adjectives and adverbs :

EAP example essays, past students