TASK DEFINITION: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
PROBLEM: The combustion of propane gas produces carbon dioxide and water vapor.

SOLUTION: The combustion of propane gas produces carbon dioxide and what else?

PROBLEM: Reptiles are described by the term ectothermic, which means their internal temperature depends on the temperature of their environment.

SOLUTION: Reptiles are described by what term that means their internal temperature depends on the temperature of their environment?

PROBLEM: Satellites are man-made devices in space that are used to observe the earth's surface.

SOLUTION:
What man-made devices in space are used to observe the earth's surface?