For centuries, explorers have risked their lives venturing into the unknown for reasons of economic benefit and national glory. Following the lunar missions of the early 1970s, Mars now looms as humanity’s next great, unknown land. But with dubious prospects for short-term financial return and with international competition in space a receding memory, it is clear that imperatives other than profit or national pride will have to compel human beings to leave their tracks on the planet’s red surface.
With Mars the scientific benefits are perhaps higher than they have ever been. The issue of whether life ever existed on the planet, and whether it persists to this day, has been highlighted by accumulating evidence that Mars once had abundant liquid water and by the controversy over suggestions that fossils of bacteria rode to Earth on a rock ejected from Mars during its early history. A definite answer about life on Mars, past or present, would give researchers inv
A. Some urgent needs.
B. Profit or national pride.
C. Economic benefit and national glory.
D. International competition in space.
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