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本帖最后由 Reader86 于 2022-10-1 12:42 AM 编辑
(a) Mars at its nearest is 56 million kilometers away, so the light travel time is:
time of travel =5.6·107km3·105kms= 187 s2
In terms of minutes, this becomes187s·1 min60s= 3.11 min
It takes a little over 3 minutes each way to communicate with a spacecraft on Mars at closest approach.
(b) At the most distant, Mars is 400 million kilometers from Earth, so we can compute the travel time for light:
time of travel =4·108km3.00·105kms= 1,330 s
We would again prefer this in minutes, so we convert:1,330s·1 min60s= 22,2 min
If SpaceX flies at light speed, only 3.11 ~ 22.2 min need from Earth to Mars.
Current spaceship speed is only 1/18,000 of light speed, therefore, it takes 40 ~ 285 days to Mars.
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