This is an easy calculation, just integrate the gravitational force to get GMm/r where r is the radius of the earth about 6378 km (or 6378*10^3 meters), M is the mass of the earth 5.9736*10^24 kilograms, G is the gravitational constant 6.67*10^(-11), and let us assume that our weight is 1000 kilograms.

Solving I get 6.247085606773283E+10 Joules. or using the figure of 120 million Joules in a tank of gas (120*10^6), I get the absurd figure of 520 tankfuls of gasoline.

This really isn’t very much, and gets me to the question — what am I doing on the earth anyhow, when I could be roaming in outer space. This is just a basic energy required, there is no thought of how it could be applied.

In MAXIMA the calculations are:

(%i1) m: 5.9736*10^24;
(%o1) 5.973600000000001E+24
(%i2) g:6.67*10^(-11);
(%o2) 6.67E-11
(%i3) 1000*g*m/(6378*10^3);
(%o3) 6.247085606773283E+10
(%i4) 6.24*10^10/(120*10^6);
(%o4) 520.0