NASA is currently upgrading ground stations utilized in the backup system for communicating with the International Space Station, the U.S. space agency said in an April 24, 2018, news release.

The primary means of communicating with the ISS is NASA’s Space Network, which mainly relies on a constellation of Tracking and Data Relay Satellites in geostationary orbit. As a backup, the agency also maintains a system of ground stations that transmit and receive very high frequency radio waves.