Over the past few centuries，scientists have been speculating on possible life forms on Mars and other planets. And Mars in particular has long been considered as the most earth-like of all planets in our solar system. Scientists predict that humans will be able to land on the planet Mars around the year 2015，and subsequently Mars would be gradually transformed into the second inhabitable Earth. If that came true，emigration to the planet Mars would not be far away.
Suppose in the next century overpopulation on earth had progressed to such an extent that it might lead to the destruction of the earth，and to solve the problem，a considerable proportion of the population had to migrate to Mars.
1. If you were required，are you willing to depart your homeland and to establish settlements as a pioneer on the new“Earth”?
2. If you were in charge of the Mars migration project，how would you decide who should enjoy the privilege /priority ( if it is) of migration? Personally speaking，do you think migration to Mars is a blessing or a misfortune?
Ⅲ. A Speech on th e Ch allen ger Disa ter
- given by Presid ent Reagan ，on J anua ry 28，1986
Nineteen years ago，almost to the day，we lost three astronauts in a terrible accident on the ground. But，we??ve never lost an astronaut in flight; we??ve never had a tragedy like this. And perhaps we??ve forgotten the courage it took for the crew of the shuttle; but they，the Challenger Seven，were aware of the dangers，but overcame them and did their iobs brilliantly. We mourn seven heroes: Michael Smith，Dick Scobee，Judith Resnik，Ronald McNair ，Ellison Onizuka，Gregory Jarvis，and Christa McAuliffe. We mourn their loss as a nation together .
For the families of the seven，we cannot bear ，as you do，the full impact of this tragedy. But we feel the loss，and we??re thinking about you so very much. Your loved ones were daring and brave，and they had that special grace，that special spirit that says,‘Give me a challenge and I??ll meet it with joy. ’They had a hunger to explore the universe and discover its truths. They wished to serve，and they did. They served all of us.
We??ve grown used to wonders in this century. It??s hard to dazzle us. But for twenty-five years the United States space program has been doing just that. We??ve grown used to the idea of space，and perhaps we forget that we??ve only just begun. We??re still pioneers. They，the members of the Challenger crew，were pioneers.
And I want to say something to the schoolchildren of America who were watching the live coverage of the shuttle??s takeoff. I know it is hard to understand，but sometimes painful things like this happen. It??s all part of the process of exploration and discovery. It??s all part of taking a chance and expanding man??s horizons. The future doesn??t belong to the fainthearted; it belongs to the brave. The Challenger crew was pulling us into the future，and we??ll continue to follow them . . .
There??s coincidence today. On tnis day 390 years ago，the great explorer Sir Francis Drake died aboard a ship off the coast of Panama. In his lifetime the great frontiers were the oceans，and a historian later said,‘He lived by the sea，died on it，and was buried in it. ’ Well，today we can say of the Challenger crew: Their dedication was，like Drake??s，complete.
The crew of the space shuttle Challenger honoured us by the manner in which they lived their lives. We will never forget them，nor the last time we saw them，this morning，as they prepared for the journey and waved goodbye and‘ slipped the surly bonds of earth’to‘ touch the face of God’.
