The dome covering a satellite dish at the Waihopai spy base, destroyed by activitists last year, is expected to be replaced at the weekend.
Preparation work is underway at the Marlborough base run by the Government Communications Security Bureau.
The dome collapsed after being slashed in a raid by the Ploughshares peace group in April last year.
Three men are to be tried over the attack.
A security bureau spokesperson, Hugh Wolfensohn, says the cost of replacing the rubberised satellite dish cover is about $1 million.
He says workers need calm conditions to install it, and the forecast for the weekend is good.