The U.S. Air Force’s second Advanced Extremely High Frequency (AEHF) secure communications satellite successfully completed on-orbit testing Sept. 24, the service announced Oct. 31.

The testing verified the performance of AEHF-2 and proved that multiple AEHF satellites can operate with the legacy Milstar constellation, according to the press release. The Air Force launched AEHF-2 May 4 from Cape Canaveral Air Force Station, Fla. aboard a United Launch Alliance (ULA) Atlas 5 rocket. Denver-based ULA is a Boeing-Lockheed Martin joint venture.

On-orbit testing for AEHF-2 included crosslink testing between AEHF-1 and AEHF-2, according to the press release. Communications terminals from multiple services utilized the command and control features of the AEHF system during the testing.

Lockheed Martin Space Systems of Sunnyvale, Calif. is currently under contract to deliver four AEHF satellites. The company also started advanced procurement of long-lead parts for the fifth and sixth AEHF satellites. The AEHF system will provide secure, jam-resistant communications for high-priority military missions. AEHF satellites will replace the five-satellite Milstar constellation the United States uses for handling critical military communications.