What are TWO issues with living in space that need to be addressed by scientists and how are they addressed?​

One of the governing factors in the difference in life style of space travelers is the absence of gravity in space. Lack of gravitational force, leads to decrease in bone density, muscle atrophy, and an overall loss of sense of orientation over a period of time.

Explanation:

Is this good collage kid?

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.