His weight on Earth doesn't depend on where he is at the moment.
Weight = (mass) x (gravity)
On the Earth's surface, the acceleration of gravity is 9.8 m/s².
So, on the surface, the astronaut weighs
(78 kg) x (9.8 m/s²) = 764.4 Newtons (about 172 pounds) .
No matter where he goes, his mass doesn't change.
But his weight does.
If he's 6R from the enter of the Earth, then he's 5 times as far from it
as when he's standing on the surface. The acceleration of gravity
out there is
( 1 / 5² ) = 1/25 = 0.04 times
the acceleration of gravity on the surface.
His weight out there is
(78 kg) x (9.8/25 m/s²) = 30.6 Newtons (about 6.9 pounds)
