To solve this problem, first, we need to determine how far Mars is from Earth at its closest approach, using the information provided.
- Distance to the Moon: 386,400 km
- Distance to Mars at its closest: 140 times the distance to the Moon
So, the distance to Mars is:
\[ \text{Distance to Mars} = 140 \times 386,400 \text{ km} = 54,096,000 \text{ km} \]
Next, we know that the spaceship takes 3 days to reach the Moon. We need to calculate the speed of the spaceship:
- Speed of the spaceship to the Moon:
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} = \frac{386,400 \text{ km}}{3 \text{ days}} \approx 128,800 \text{ km/day} \]
Now we will use this speed to estimate how long it would take to travel to Mars:
- Time to reach Mars:
\[ \text{Time} = \frac{\text{Distance to Mars}}{\text{Speed}} = \frac{54,096,000 \text{ km}}{128,800 \text{ km/day}} \approx 420 \text{ days} \]
Now we convert days to years:
\[ \text{Years} \approx \frac{420 \text{ days}}{365 \text{ days/year}} \approx 1.15 \text{ years} \]
The closest option provided is "about 1 year."
Thus, the best answer is about 1 year.