By Newton's second law, the forces acting on the astronaut (the normal force n of the rocket pushing up on the astronaut, and her weight mg pulling her downward) have a net effect of
n - mg = ma
where
m = 88.9 kg
g = 9.80 m/s²
a = 47.2 mi/s² ≈ 75,960 m/s²
Then
n = m (g + a) ≈ 6.75 × 10⁶ N