12_sk_sci9_se_ch12:Layout 1 3/28/11 8:21 AM Page 394 Space exploration improves our knowledge and gives us beneficial 12 technologies and has significant costs and hazards. Outcomes What you will learn: • Humans throughout history, including First Nations and Métis peoples, By the end of this chapter, have interpreted their observations of the universe and used that you will: knowledge to aid them in everyday life. • examine how various cultures past and present, • Canada has made significant contributions to space research, technology, including First Nations and and exploration. Métis, understand and • The importance and benefits of space exploration often outweigh the costs, represent astronomical hazards, and issues surrounding it. phenomena • analyze human capabilities • Exploring the universe gives us a greater understanding of its nature while for exploring and under - also advancing the development of technologies for use on Earth. standing the universe, including technologies and programs, that support such exploration Astronaut Stephen K. Robinson is mounted on the end of the Canadarm2 robotic arm to make repairs to the International Space Station in orbit around Earth. Before Writing Signalling Organizational Patterns Good writers give signals to the reader about the way text is organized. They use dates and sequencing words (such as first, next, then) to indicate time Key Terms order for a chronological or sequential account. Often, in scientific writing, • artificial satellite writers will also use a problem-solution pattern, describing a problem and • geostationary orbit suggesting possible solutions. Skim section 12.1, and decide which type • microgravity • spinoff of organizational pattern is used. 394 UNIT D ©P 12_sk_sci9_se_ch12:Layout 1 3/28/11 8:22 AM Page 395 Space Exploration 12.1 Here is a summary of what you will learn in this section: • Throughout history, humans have explained phenomena in the universe based on what they are able to observe. • As telescopes, space probes, and other technologies have advanced, humans have been able to explore farther out into space. Such observations provide evidence that leads us Figure 12.1 An artist’s concept of Pioneer 11 in flight against the backdrop of Saturn’s rings. to different conclusions about Pioneer 11 is expected to be approaching a star in the constellation Aquila in about 4 million years. our understanding of our solar system and the universe. Into the Frontier of Space In 1972, the space probe Pioneer 10 was launched by the National Aeronautics and Space Administration (NASA), the U.S. agency responsible for the country’s space program. The mission of this unpiloted spacecraft was to fly past Jupiter and continue on to the outer solar system. Pioneer 10 transmitted images of Jupiter back to Earth that revealed details humans had never been able to see before. The probe continues to travel through space, but no signals have been received from it since January 2003. By August 2009, Earth-based telescopes tracking Pioneer 10 saw that it was already more than 1000 times farther from the Sun than Earth. If nothing interferes with its progress, it could pass the star Aldebaran in about 2 million years. In 1973, Pioneer 11 was sent on a similar mission as its sister probe with the added task of capturing images of Saturn (Figure 12.1), as well as Jupiter. No communication has been received from the probe since 1995. Space probes Voyager 1 and Pioneer 10 Neptune Uranus Voyager 2 Voyager 2 were launched in 1977 Pioneer 11 to study Jupiter, Saturn, and the outer solar system. Voyager 1 is Saturn the most distant human-made object in space (Figure 12.2). Voyager 1 By February 2011, Voyager 1 Figure 12.2 The current location and direction of travel of the Pioneer 10 and 11 was 116.082 AU away. space probes, as well as Voyager 1 and 2 12.1 Space Exploration 395 ©P 12_sk_sci9_se_ch12:Layout 1 3/28/11 8:22 AM Page 396 Both Pioneer craft have now left the solar system and are travelling into space like two ghost ships. The two Voyager craft continue to transmit data to Earth, but their future will be like that of the Pioneer probes. Still, the purpose of all four craft has not entirely ended. Aboard each Pioneer probe is an engraved plaque showing a man and woman, the solar system, and other basic information to indicate where Earth is located (Figure 12.3). Aboard each Voyager probe is a “golden record,” with Figure 12.3 Peaceful greetings on the plaque aboard recorded sounds and pictures of Earth. Pioneer 10 and Pioneer 11 D23 Quick Science Greetings from the People of Earth Each of the Pioneer space probes that have left the Questions solar system carries the plaque shown in Figure 12.3. 3. What does our sending information like this It is hoped that other life forms that think enough like out into space suggest about our own ideas humans might find one of the probes and be able to of the universe? use the plaque’s information, even millions of years from now, to locate Earth. 4. What does the plaque information assume about the nature of any aliens who might acquire it? Purpose 5. If you were to design your own plaque, what To examine the implications of sending information would you put on it? Explain. about humans into space 6. If the plaque can last a million years, will it Procedure outlive the human race? Explain your answer. 1. Working in a small group, read through the 7. Would aliens capable of finding the plaque following questions. Discuss each question already know about Earth because of our radio within your group, and record your answers in transmissions? point form. If there are differences of opinion 8. Is the most likely finder of the plaque going to be within your group, be sure to note them as well. future human space travellers who have forgotten 2. When you have discussed all the questions, be their early roots? Explain your answer. prepared to share your answers with the class. Pose New Questions 9. What would you like to know about the life forms that may find the plaque? 10. What issues could there be if the plaque is found? What if it is not found? 396 UNIT D Exploring Our Universe ©P 12_sk_sci9_se_ch12:Layout 1 3/28/11 8:22 AM Page 397 The Evolution of Astronomers’ Tools infoBIT The idea that humans could send spacecraft such as Pioneer 11 Observation with the Unaided Eye and 12 so far away to gather information about the universe People can observe the would have been unimaginable a century ago. Still, today’s planets Mercury, Venus, accomplishments in technology and scientific astronomy Mars, Jupiter, and Saturn are built on the observations, engineering prototypes, without a telescope. The and scientific problem-solving skills of the past. planets in the night sky are Astronomy has been around for at least 4000 years. Early on, often mistaken for stars. astronomers used their eyes to observe celestial objects. Step by step, However, stars twinkle our understanding of space and Earth’s place in it has progressed, and planets do not. thanks in large part to the improvement of the tools available to observe, record, measure, and analyze what we see. As you read in Chapter 9, humans are very inventive and have developed tools over the centuries to help them better understand astronomical phenomena. Sundials, for example, have been used for more than 7000 years to measure the passage of time (Figure 12.4). Ancient Egyptians invented a device called a merkhet to chart astronomical positions and predict the movement of stars. In the second century, Egyptian astronomers designed a tool called a quadrant to measure a star’s Figure 12.4 The upright part of a sundial casts a shadow onto the face of the dial. The position and height above the horizon (Figure 12.5). For centuries, movement of the shadow provide an accurate way Arabian astronomers used the astrolabe to make accurate to track time, at least during sunny days. charts of star positions. In the 14th century, astronomer Suggested Activity • Levi ben Gerson invented the cross-staff to measure the D24 Science, Technology, Society, angle between the Moon and any given star. With each of and the Environment on page 401 these innovations, astronomers made new discoveries and gained more knowledge about what they were seeing. quadrant astrolabe cross-staff Figure 12.5 The inventiveness of astronomers led them to develop many tools to help them observe, record, and measure celestial activity. 12.1 Space Exploration 397 ©P 12_sk_sci9_se_ch12:Layout 1 3/28/11 8:22 AM Page 398 Telescopes eyepiece lens Optical Telescopes The invention of the telescope in the Netherlands in the late 16th century was a technological breakthrough that revolutionized Western astronomy. Suddenly, astronomers such as Galileo could see more in the night sky than ever before. Telescopes detected exciting details about Earth’s closest planetary neighbours and revealed the existence of other astronomical bodies in the solar system. With the telescope, astronomers learned that what lay beyond Earth was greater than they had ever imagined. The first telescope was a simple refracting telescope. Refracting telescopes use two lenses to gather and focus starlight (Figure 12.6). However, there is a limit to how large a refracting telescope can be. Lenses larger than 1 m in diameter warp under their own weight and distort images, like trying to look at objects through the bottom of a pop bottle. Reflecting telescopes use mirrors instead of lenses to gather and focus light (Figure 12.7). At one end of a reflecting telescope is a large concave mirror made from glass-like material that is coated with a thin layer of metal.