First off 60kg is the mass, not the weight.
All you have to do is simply find the vector sum of all acceleration on the object, in our case of the astronaut that would be:
assuming the acceleration is constant. Deripty derp:
The "g-force" is often expressed as relative to the strength of the Earth's gravitational field (9.809ms^-2), hence you could say:
If you're given the weight, it's a simply matter of following the procedure:
Note that both "g" and "a_total" are considered to be vertical and directed in the same direction, g in the last equation represents the total downward acceleration and not just the constant representing the strength of our gravitational field.