Chapter 1 - Summary

• Science is a reflection of humanity's desire to explore.  Our innate curiosity drives us to want to understand our universe.  Mars, more than any other planet, has stimulated man's interest in space exploration.  Recent discoveries of possible signs of life on Mars have renewed that interest.
• Science is a method of gaining knowledge about the world.  All science relies on collecting empirical data that can be explained by hypotheses.  In turn, all hypotheses must be supported by empirical data.  Technology makes use of our knowledge, which may or may not be derived from science, to produce something that humans find useful.
• Exploration of Earth was most successful when it made use of technology appropriate to the local environment.  Using local resources in a suitable way resulted in successful voyages of discovery.  Similarly, exploration of space will also be successful if we make use of the resources available on the planets.
• The science of rocketry is based on Newton's second and third laws of motion.  The force required to accelerate a rocket's mass comes about by ejecting gases at high velocity from the rocket.  The rocket then reacts by accelerating in the opposite direction.
• Rockets are propelled by combustion reactions.  A variety of fuels are used, since different fuels have different characteristics that make them better suited for different tasks.  It takes a great deal of fuel to lift a rocket from Earth, because of gravity, because of the resistance of the Earth's atmosphere, and because we need to accelerate it to a very high velocity.  Even with the most efficient rocket design possible, almost 90% of the mass of a rocket going into Earth orbit is consumed as fuel.
• A spaceship travels from one planet to another using an elliptical orbit that intersects the orbits about the Sun of the home and destination planets.   The most energy efficient orbit may not be the one chosen for a manned mission, as it may take too long to get from one planet to another.  Weightlessness, and exposure to radiation are problems for humans that become very serious if the trip is of long duration.
• Because it takes enormous amounts of fuel to lift a spaceship out of the Earth's atmosphere, our journey to Mars will probably start from a space station in Earth orbit.  Even then, we can save a great deal of energy if we make use of the carbon dioxide in the Martian atmosphere to generate the fuel we need to return to Earth.

For Discussion:

Discuss the following review questions to check your understanding of the concepts in this chapter.

1. Using examples from science fiction novels, describe how our perceptions of Mars have changed since the 1700's.
2. How is curiosity a motivation for most scientists?  How does curiosity affect our attitude towards Martian exploration?
3. What is/are the difference(s) between science and technology?
4. Amundsen and Scott were two explorers who were racing to reach the South Pole.   Amundsen reached the Pole first and all his team survived.  Scott was second to the Pole and all his team died on the return trip.  How was Amundsen a better explorer than Scott?  Discuss how modern-day explorers must be like Amundsen if they are to be successful in an expedition to Mars.
5. Explain why rockets are built in stages.
6. Why is it dangerous for astronauts to spend too much time in space?
7. Given that there are health concerns associated with osteoporosis, especially in women, should physical education be a compulsory activity in schools?  Discuss the pros and cons of this issue.