![GRACE-FO Build](/rails/active_storage/blobs/redirect/eyJfcmFpbHMiOnsibWVzc2FnZSI6IkJBaHBFUT09IiwiZXhwIjpudWxsLCJwdXIiOiJibG9iX2lkIn19--fd69dc604e91e84cd51726683b8e09bf3bfbac49/FM1_before_thermal_tests.jpg?disposition=inline)
Satellite FM1 is shown in December 2016 in a transport fixture at Airbus in Germany before being loaded into a thermal vacuum chamber for testing. Credit: Airbus
The twin satellites of the GRACE-FO mission are identical, built so that either one can lead, or follow, as needed. This helps prolong the life of the spacecraft and their components.