A probe is launched from the surface of Earth into a circular orbit 1000km above the surface. An identical launch is made on Mars. Given G=6.67×10−11Nm2kg−2, Earth’s mass 5.97×1024kg, radius 6.4×106m, Mars’ mass 6.42×1023kg, radius 3.4×106m, the ratio
energy required per kilogram on Marsenergy required per kilogram on Earth
\nis approximately
a) 1
b) 0.5
c) 5
d) 3