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TOEFL【Integrated Writing】TPO50

Scientists are considering the possibility of sending humans to Mars in the coming decades. Although there have been successful manned missions to the Moon in the 1960s and 1970s, Mars is 150 times further away from Earth than the Moon is. Thus the project of sending humans to Mars would require solving an array of problems the Moon missions did not have to face.

One problem is that a round-trip to Mars and back is likely to take at least two years. The trip to the Moon lasted only a few days, and it was easy to bring enough supplies of food, water, and oxygen; but the cargo capacity of space vehicles is too limited to put on board the food, water, and oxygen required by a crew for a period of two years. Without those essentials, though, a Mars mission is impossible.

A second problem is that astronauts on the Mars mission would be in the zero-gravity environment of space for many months at a time. Spending a long time in the zero-gravity environment has negative effects on the human body, such as decreased muscle mass and lower bone density. Over the course of a two-year mission, the effects would be so severe, they would make it impossible for humans to make the trip without experiencing grave medical problems.

Finally, astronauts on a mission to Mars would be exposed to dangerous levels of space radiation, much of which comes in the form of charged particles emitted by the Sun. Earth's magnetic field, which normally protects us from dangerous solar radiation, would not be able to protect a spaceship traveling in interplanetary space. Constructing a shield that would protect the whole spaceship from space radiation is at present impossible because it would add too much weight to the ship.

Personal Writing

The passage contributes the difficulty of going to Mars to limited supply, zero gravity, and dangerous radiation. However, the professor argues that these problems can be solved.

First, limited supply. The passage says that unlike traveling to Moon within some days, going to Mars takes two years, a time too long to carry enough supply into spaceships. However, the professor argues that hydroponics can be used in the small area to cultivate plants and support drinking water in this water recycle. By photosynthesis from absorbing carbon dioxide to releasing oxygen, she add, astronauts can breathe fresh air --the solution of supply. 

Second, zero gravity. The passage states that staying in zero gravity environment for long periods makes humans decrease muscle mass and bone density. However, the professor argues that some techniques learned from astronauts taking many months in zero gravity can safely manage health condition. She explains that exercising regularly can maintain the muscle mass and taking vitamins and calcium can slow down the decreasing bone density in zero gravity.

Third, dangerous radiation. The passage claims that due to the weight of spacecraft, building whole shield to protect the ships from solar radiation is impossible. However, the professor argues that the radiation doesn't happen at all times but occasionally when sun is particularly active. She emphasizes that tools for monitoring radiation and small radiation-proof shuttles in spacecrafts can protect astronauts from the occasionally dangerous radiation.

Word: 236

note：

Reading ： X go to Mars

argument 1：limited supply  →  2 years, Moon days / X space

argument 2： zero gravity → long / ↓ bone, muscle  

argument 3：dangerous radiation  → sun charged par. /  shield, weight

Listening ：  X

argument 1： S → hyp,  in water  / recy , drinking ,  air  

argument 2：G → know tech, orbiting station / exercise, vitamins & calcium 

argument 3：R → X all time, occ active / monitor, stay in sheild 

Listening script

A trip to mars would definitely be challenging but scientists have proposed solutions to the problems the reading selection discusses.

First of all, food, water and oxygen. Well astronauts can use hydroponics. Hydroponics is a technique for growing plants with their roots in water rather than in soil. It requires relatively little space. Using hydroponics, the astronauts should be able to cultivate food crops in the spacecraft. In addition, the hydroponic will grow plants with recycle waste water and release it as clean water vapor, which can be collected as drinking water. And of course, all plants absorb carbon dioxide and release oxygen. So thanks to hydroponics the astronauts will also have fresh air to breathe.

Second, the effects of zero gravity. Over the last few decades, we have launched several space stations orbiting the earth. And a number of astronauts have spent many months on them in a zero gravity environment. These astronauts have learned to use several techniques to safely manage the effects of zero gravity. For example, regular exercise prevents the decrease in muscle mass. Likewise, taking vitamins and minerals like calcium slows down the decrease in astronauts’ bone density.

Third, solar radiation. Astronauts traveling to Mars will be exposed to some solar radiation but this radiation will not be at dangerous levels all the time. The sun only releases dangerous amounts of radiation occasionally, during periods when it is particularly active. In order to avoid this threat, the spacecraft could be equipped with special instruments that monitor solar radiation and with a small shelter that shield against radiation but doesn’t add much weight to the ship. Most of the time, the astronauts will go about their normal business in unshielded areas of the spacecraft. But when their instruments detect increased radiation, they could stay in the small shielded area until the danger has passed.