AST Constellation Plans Raise Alarms From Amateur Radio Operators Worldwide

The opposition "reflects a long tradition of vigilance and advocacy within the amateur radio community," emailed Rob Hardenberg, a committee chair with the Netherlands' Society for Experimental Radio Research (VERON). "While our organizations have frequently engaged with regulators about spectrum threats -- both at the FCC and elsewhere -- the scale and commercial nature of this constellation make it particularly urgent. This is not just about protecting a hobby; it is about safeguarding a critical resource for technical experimentation, emergency communications, education, and scientific advancement."

Hardenberg told us he learned about the AST developments through international amateur radio forums and mailing lists and later heard about them at the International Amateur Radio Union Region 1 Interim Conference in Paris in April. There, "it was already recognized as a serious concern," he said. "The recent expansion of AST's license application highlighted just how urgent and global the issue of 'intruders' in the 430-440 MHz band has become."

In comments posted this week, VERON said AST's TT&C plan is "a matter of serious concern to our community." It said 430.5, 432.3, 434.1, 435.9 and 439.5 MHz are used for sensitive weak-signal communication and amateur satellite downlink operations throughout Europe. AST satellite transmissions "have already been detected in Europe, underlining the real risk of harmful interference."

Roman Kudlac, president of the Slovak Amateur Radio Association, said in an email that this represents "an unprecedented case where AST is requesting the allocation of frequencies for commercial operation in the 430-440 MHz amateur band in contravention of the current ITU band plan." The group also filed comments. "The piquant part is that the U.S. FCC wants to authorize operations that would affect radio amateurs outside the U.S., since the terrestrial stations are located outside the U.S.," Kudlac told us.

German amateur radio operator Tobias Schlegel, who also submitted comments in opposition, emailed us that several national and international ham organizations have helped organize "the 'resistance.'" Novice class operators' heavy use of the band "might be the reason for the resonance," he said.

In a partial opposition, the American Radio Relay League said AST's ask for 430-440 MHz access was "unprecedented." The spectrum swath isn't allocated domestically or internationally for satellite TT&C operations, yet signals in the band from AST's five satellites "have been observed throughout the world," even though the satellites are authorized to communicate only with five ground stations outside the U.S. In addition, the group said the satellites apparently have transmitted continuously in the 430-440 MHz band, not just when in communication with one of those five ground stations. Allowing 243 more satellites to use the band "would effectively usurp this band’s allocated use."

The Japan Amateur Satellite Association argued that with commercial TT&C services having alternative spectrum available, AST doesn't need the 430-440 MHz band.

The nonprofit Radio Amateur Satellite Corp. also urged the FCC to deny AST's use of 430-440 MHz, citing the need to protect the 435-438 MHz band, which is used by the amateur satellite service. The group said AST’s experimental satellite BlueWalker-3, a precursor to its planned constellation, still interferes with amateur satellite service operations nearly three years after launch.

NASA said its initial analysis shows that projected light pollution from the AST constellation would exceed thresholds recommended by the astronomical community. NASA and AST continue to evaluate the constellation’s trackability and end-of-life disposal plans, the agency added.

Any authorization that AST obtains in the 2025-2110 MHz band should include a frequency coordination requirement for operations that may cause harmful interference to broadcast auxiliary service, local TV transmission service and cable TV relay service licensees, the Society of Broadcast Engineers said.

In a Space Bureau application Monday, AST asked to add supplemental coverage from space use of the 700 MHz band licensed to FirstNet, bringing SCS broadband services to first responders.