Terraform
From Starfleet Commander
Terraform
The terraforming feature allows players to increase the number of fields on a colonized planet by five by spending credits. The credit cost is:
2F2
where F is equal to the number of fields a planet currently has.
This feature allows players to increase the number of fields without abandoning the planet and losing all structures and the required colony forming ship in the process.
To 'terraform', you must select the planet where you would like to add fields and click on the "Terraform" button found on the Buildings or Home page.