Mum needs you to release the Cargo Valve.
If the Gravity Lift is fixed, use it to travel upwards.
You can show every hotspot by pressing the space bar.
Travel up the Gravity Lift, then go though the door to the flight deck. You'll find what you need on the flight deck.
To release the Cargo Valve, interact with the holo-panel. It is in the middle of the scene; a grey rectangle with large white button and six, smaller, red and white buttons.
Return to Mum.