AST & Sci­ence LLC (oper­at­ing as AST Space­Mo­bile) cur­rent­ly deploys com­mer­cial satel­lites in Low Earth Orbit that uti­lize spec­trum allo­ca­tions with­in the 430–440 MHz ama­teur and ama­teur satel­lite bands for Teleme­try, Track­ing, and Com­mand (TT&C) oper­a­tions. The satel­lites, des­ig­nat­ed Blue­bird 1–5, were launched on Sep­tem­ber 12, 2024, and func­tion under an FCC Space Bureau autho­riza­tion pur­suant to Arti­cle 4.4 of the ITU Radio Reg­u­la­tions. This pro­vi­sion per­mits admin­is­tra­tions to autho­rize sta­tions using fre­quen­cies that are not in accor­dance with the ITU‑R Table of Fre­quen­cy Allo­ca­tions or oth­er rel­e­vant reg­u­la­tions, pro­vid­ed such use does not cause harm­ful inter­fer­ence to oth­er admin­is­tra­tions autho­ris­ing ser­vices that are in accor­dance with the Table of Fre­quen­cy Allocations.

Blue­bird satel­lites employ the fol­low­ing fre­quen­cies for TT&C oper­a­tions with 50 kHz band­width uti­liz­ing Gauss­ian Fre­quen­cy Shift Key­ing (GFSK 2400): 430.500 MHz, 432.300 MHz, 434.100 MHz, 435.900 MHz, and 439.500 MHz. Addi­tion­al­ly, AST’s pro­to­type satel­lite Bluewalker‑3 trans­mits teleme­try on 437.500 MHz. These fre­quen­cies are not intend­ed to car­ry the ser­vice user traf­fic, and the use of these UHF fre­quen­cies is pro­posed for excep­tion­al cir­cum­stances when the nor­mal Q and V Band TT&C chan­nels are not use­able (40 and 60 GHz bands).

In June 2025, the FCC Space Bureau accept­ed a fur­ther appli­ca­tion from AST & Sci­ence LLC for the deploy­ment of 243 addi­tion­al satel­lites intend­ed to use the 430–440 MHz spec­trum for teleme­try purposes.

Sup­port­ing mate­r­i­al for the new appli­ca­tion also sug­gests that use of the 430 – 440 MHz range by the new addi­tion­al satel­lites may be lim­it­ed as these are expect­ed to use the S‑band (around 2 GHz) exclu­sive­ly for TT&C when needed.

The 430–440 MHz band sup­ports a range of ama­teur and ama­teur satel­lite appli­ca­tions, includ­ing weak-sig­nal com­mu­ni­ca­tions, space com­mu­ni­ca­tions, dig­i­tal tele­vi­sion, data trans­mis­sion, repeaters, and oth­er uses. There is no spe­cif­ic shar­ing study con­sid­er­ing the impact of the TT&C trans­mis­sions in the 430–440 MHz band on these ama­teur appli­ca­tions despite the Pri­ma­ry sta­tus of the ama­teur ser­vice allo­ca­tion in Region 1 and 11 coun­tries in Region 2.

The Inter­na­tion­al Ama­teur Radio Union (IARU) and its mem­ber soci­eties have expressed con­cerns regard­ing the lack of any tech­ni­cal assess­ment on the poten­tial inter­fer­ence aris­ing from AST satel­lite TT&C trans­mis­sions affect­ing the afore­men­tioned appli­ca­tions. The IARU main­tains that invok­ing Arti­cle 4.4 of the Radio Reg­u­la­tions is inap­pro­pri­ate in this con­text, giv­en the con­sid­er­able risk of inter­fer­ence asso­ci­at­ed with AST’s use of the ama­teur allocation.

To address these issues, the IARU has com­mu­ni­cat­ed its posi­tion in cor­re­spon­dence to the Direc­tor of the ITU Radio­com­mu­ni­ca­tions Bureau. IARU mem­ber soci­eties are encour­aged to engage their respec­tive reg­u­la­to­ry author­i­ties about the impli­ca­tions of AST satel­lite TT&C trans­mis­sions with­in the 430–440 MHz band and to inform their mem­bers accordingly.