Final Answer:
The required speed to achieve the time dilation observed in the scenario is not determinable within the bounds of special relativity. C. $30,000
Step-by-step explanation:
According to the principles of special relativity, time dilation occurs when an object moves at relativistic speeds. The formula for time dilation is
, where t' is the dilated time, t is the proper time (time measured on the moving object), v is the velocity, and c is the speed of light. Given that the round-trip felt like 12 years on Earth (t' and the proper time t on the spacecraft was 8 months
, we can rearrange the time dilation formula to solve for v.

Here, v represents the velocity required, and
implies an imaginary number, which is impossible in this context. This indicates that the given scenario, as described, doesn't conform to the principles of special relativity based on our understanding. Therefore, the choices provided regarding cost are not relevant to the solution of this problem in the context of special relativity.(C)