SECTION 3 – Questions 25 – 40

MARS: Are We Close to Finding Life?

A        No planet has teased the imagination as much as Mars. In ancient Greece and Rome, the planet’s fiery red hue made skywatchers think of their god of war. In the 19th century, astronomer Percival Lowell thought he saw canals on Mars; his observations triggered a flood of  novels  and science fiction stories about strange and wonderful beings thought to inhabit the Red Planet.   Mars, the fourth planet from the sun, has often been called a sister planet to our own Earth. A “day” on Mars lasts 24-and-a-half hours, just 30 minutes longer than here on Earth. The planet is tilted on its axis by 25 degrees, just two degrees more than the Earth’s tilt. Because of its greater distance from the sun, however,  Mars takes substantially  longer to complete each orbit, a “year” on Mars lasts 668 earth days, nearly twice as long as a year here on Earth. Mars has two small, irregularly shaped moons, Phobos and Deimos, each less than 30 km across. Because of its small size, the pull of gravity on the planet’s surface is just 38 per cent as strong as on Earth (a 200 pounds man would weigh just 76 lbs. On Mars). And because of its weak gravity, Mars has retained only a thin atmosphere­ about 100 times thinner than Earth’s. Its main component (95 per cent) is carbon dioxide. It can be windy, though with giant dust storms sometimes engulfing the entire planet.  Because of its thin atmosphere and its distance from the sun, Mars is a very cold world. Although midsummer temperatures can reach 26, it can also drop to a numbing -111.

B       Besides its vast, rocky deserts, Mars also has enormous canyons such as the 5000-kilometre Valles Marineris, as well as giant extinct volcanoes like 27-km-high Olympus Mons, the largest volcano in the solar system. The planet also has intriguing channels that look as though they were carved by flowing water–suggesting that Mars may once have been both wetter and warmer than it is today. Two distinct polar ice caps can be seen even through small telescopes. The north cap–the larger of the two–is mainly normal ice (frozen water), while the southern cap seems to be mostly frozen carbon dioxide. Why the two caps are so different is a mystery.

C       The question of life on Mars–either past or present–remains a great motivator in the exploration of the Red Planet. True, no signs of life have been discovered on Mars, but scientists can’t rule out the possibility that microbial life did, at one time, evolve there. With its giant volcanoes, gaping canyons, and vast deserts, Mars remains as intriguing as ever, but the lack of water makes many scientists pessimistic including Dr. Jane Renfrew, although she believes that it’s still possible that microbial life has survived below the surface. A number of scientists, including Sam Watson from MIT, have also raised the intriguing possibility that life on Earth may have originated on Mars. Material from Mars has reached Earth in the form of meteorites; if there were microbes embedded in those rocks, it’s possible that they could have eventually “taken root” on Earth. Of course, one could argue that it evolved on Earth first, and arrived on Mars via a wayward meteorite, as Dr Bill Verten another MIT scientist has proposed.

D     There’s evidence suggesting that water once flowed across the Red Planet. An ocean may have once covered the planet’s northern hemisphere; as well, images from Surveyor and other spacecraft show channels that may well have been carved by flowing water billions of years ago. Why would the ocean be in the north? Maps of Mars highlight the contrast between the planets’ hemispheres: The north is very low and smooth, while the south is rough, mountainous, and heavily cratered. The northern hemisphere, on average, is five kilometres lower than the southern hemisphere. That difference in elevation would have affected the flow of water, thought to have been present on the Martian surface billions of years ago. Any water that was present, Paige says, would have tended to flow northward–perhaps creating a vast ocean in the planet’s northern hemisphere. He cautions that there is no direct evidence for this, but says “we can’t rule out the possibility of a large amount of water there.”

E     So where did all the water go? Scientists have come up with a number of models, but none of them is quite satisfactory. Because of the planet’s cold temperature and thin atmosphere, liquid water is not stable on the Martian surface. Any water would either evaporate into the atmosphere, or freeze and be absorbed into the soil. It’s possible that most of the water evaporated, and then the water molecules–continuously bombarded by solar radiation–may have broken down into their components, hydrogen and oxygen. These gases may then have been lost into space. But current models suggest that this should have taken many billions of years — in other words, there hasn’t been enough time to lose so much water. The water mystery is one of the most puzzling that scientists hope the current crop of Mars missions will solve those rocks, it’s possible that they could have eventually “taken root” on Earth. Of course, one could argue that it evolved on Earth first, and arrived on Mars via a wayward meteorite, as Dr Bill Verten another MIT scientist has proposed.

F     Launched in January 1999, the lander was the latest in a series of low-budget NASA space missions, designed to “do more with less.” The price tag for the Mars Polar Lander was about $330 million US–a tiny fraction of the cost of the billion-dollar Viking probes of the 1970s. Still, an independent inquiry headed by Erich Svenson blamed the trouble on inadequate software systems testing, a result of underfunding. On December 3, 1999, the Mars Polar Lander which failed in its mission, was supposed to have touched down at the edge of the planet’s south polar ice cap. Why such a southerly location?

Scientists believe the layers of dust and ice close to the poles contain a kind of layered record of the planet’s climate history (just as a tree’s rings tell the story of the plant’s growth history); for the first time, they would be able to study those layers. “We’re landing on a completely different part of the planet than we’ve explored in the past, and we know   very little about the terrain,” says David Paige of UCLA, one of the project scientists with the Mars Polar Lander. “It has a real exploratory flavour to it.”

G     It may be several decades before the first humans set foot on Mars, but some scientists believe they’ve got the next best thing–and the perfect rehearsal space–here in Canada.  A group called The Mars Society is planning a US $1.2-million simulated Mars station on Devon Island, high in the Canadian Arctic. The island is extremely cold and dry; the landscape is covered with rocky ridges, valleys, and meteorite-impact craters And, scientists believe, it likely witnessed the same kinds of geological processes that shaped the surface of Mars. The Mars Arctic Research Station may be complete by the summer of 2000. The Mars Society is trying to raise money for the station through private and corporate donations; it has also been negotiating with NASA in the hope of sharing resources. The facility will let scientists and engineers test everything from water-recycling methods to land rovers and drilling equipment–the sort of machinery that will be crucial if a manned mission to Mars is given the go-ahead. And, perhaps         most importantly, it will simulate the kind of self-contained, isolated environment that anyone living on Mars will have to get used to.

H     Scientists hope to send a sample-return mission to the Red Planet in the early years of the next decade (possibly as early as 2005), and there’s speculation that a manned mission–almost certainly an international  collaboration –could be underway within about 20 years. Many sc1ent1sts, including Dr. Zuber at MIT, see a manned mission as inevitable. Now that we’ve explored the moon, the Red Planet seems to be the next logical step in our species’ exploration of the solar system. “It’s going to require the political will for it to happen,” she says, “but when that occurs, there will be plenty of people lined up willing to help.”

Questions 25 – 29

The passage has 8 paragraphs labeled A-H. Match the paragraphs that contain the following information and write your answer in boxes 25 -28 on the answer sheet.

25. Theories about the disappearance of water on Mars
26. Landscape features on Mars
27. A place to practice a Mars landing
28. An area of Mars which is needed to research to unlock its secrets
29. The reasons that people believe that a large body of water once existed on Mars

Questions 30 – 35
Are the following statements consistent with the information in the passage?
In boxes 30 – 35 on your answer sheet write

YES   if the statement is supported in the passage
NO     if the statement is contradicted in the passage
NOT GIVEN   if the statement is neither supported nor contradicted

Example                                                                                                        Answer
The southern pole of Mars has secrets that may reveal the planets age. Yes

30. The reason the two polar caps are so different is due to the atmosphere.
31. Mars has channels but no canals.
32. You would weigh less on Mars.
33. The main reason that scientists doubt that life exists on Mars is the extreme weather conditions there.
34. Future astronauts to Mars will probably first practice in the Canadian Arctic.
35. Mars is rich in resources that may prove useful to Earth one day.

Questions 36 – 40

Complete each of the following statements WITH THE SURNAME of a person mentioned in the reading passage. Write your answers in boxes 36-40 on your answer sheet. The first answer has been done for you in bold letters.

Mars has always been fascinating, and once a scientist by the name of … Lowell… believed he had discovered a sophisticated set of canals. Similar to those of (36)… believes that there was a huge ocean in the northern part of Mars. Not all scientists are convinced that there is life, and some, like … (37)… need more proof. Even if microbial life is found, there is always the possibility that  it  originated  on Earth,  as …(38)… believes may be possible. To get answers to these questions and more, the government must commit more resources, to exploration. However, currently NASA seems unwilling to commit much money, which scientists like  .(39)… believe caused the last failure of the Mars Polar Lander. Still, scientists such as .. .(40)… believe a manned mission will occur once the political will is there.

Answers
36. _____________
37. ______________
38. ______________
39. ______________
40. ______________