WASHINGTON — The U.S. Navy has developed a multipronged strategy for mitigating a looming gap in UHF satellite capacity that includes placing a dedicated payload on a commercial satellite, but industry officials with a stake in the matter say the plan falls well short of what the service needs.

The Navy is responsible for providing narrowband satellite capacity to U.S. military users around the world. Today the service depends on its eight remaining UHF Follow-On (UFO) satellites, the last of which launched in 2003, two previous-generation spacecraft and capacity leased on two commercial satellites.

The Navy’s next-generation Mobile User Objective System (MUOS) has encountered development difficulties and is now expected to launch in December 2011, 21 months later than originally planned. Each MUOS satellite will have a UHF payload similar to those on the UFO satellites, plus another, more sophisticated payload expected to provide a tenfold increase in capacity. The plan is to launch five MUOS satellites, four for operational use and one on-orbit spare.

But because of the MUOS delay — along with degradation of the UFO constellation — the Navy is facing a period of at least 11 months during which the predicted availability of UHF capacity dips below a required threshold established by U.S. Strategic Command, according to the Navy’s “UHF Augmentation and Constellation Sustainment Plan,” delivered to Congress in March. The Navy is required to maintain a 70 percent likelihood of UHF capacity availability equivalent to eight fully functional satellites.

During May the Navy will begin fielding the first 500 UHF ground terminals upgraded to use a new Integrated Waveform. This new technology is expected to double the number of users that can use a given channel, the plan said. Additionally, the Navy has reconfigured the communications payload on UFO-11, the last satellite in the series, to provide more channels. That satellite may also have its power cranked up in order to deliver more capacity, although this could shorten its lifespan.

Another option under consideration is loosening the orbital station-keeping requirements of some UFO  satellites to save fuel and thereby extend their operational lives. The satellites are required to maintain orbital inclinations of no more than 8 degrees, but if this is relaxed to 10 degrees, the satellites can conserve fuel while still covering up to 98 percent of their originally assigned areas, the plan said. One of the commercial satellites the Navy uses, Intelsat’s Leasat 5, is also being allowed to drift to an orbital position that will require less fuel for station keeping, it said.

This year the Navy plans to launch TacSat-4, a Naval Research Laboratory-built demonstration satellite with a UHF payload that will operate in a highly inclined low Earth orbit. Depending on the results of a military utility assessment, the Navy may be able to provide a number of that satellite’s UHF channels to users in two operational areas three times each day for periods of a couple hours, the plan said.

For the future, the Navy recently signed an agreement with the Australian Defence Force that will allow it to use UHF capacity on a planned commercial satellite in exchange for Australian access to MUOS capacity. The Australians are leasing an 18-channel UHF payload that will fly on the Intelsat 22 craft scheduled for launch in 2012.

The Navy plan also includes buying its own commercially hosted UHF payload. The Navy investigated this option for several years before concluding it would not be ready in time to meet its needs, but the 2010 National Defense Authorization Act directed the service to have another look.

The Navy plan says a commercially hosted payload is “in work” and will provide a capability no earlier than 2013, although no formal requests for information or proposals from industry have been released. Navy spokesman Steve Davis did not respond to a request for additional details about the service’s plans for the commercially hosted payload.

While the Navy’s current plan does provide some additional capacity to mitigate the anticipated UHF shortage, it will not fully close the gap, said Franklin “Judd” Blaisdell, director of space and Air Force programs for Raytheon Network Centric Systems.

“What the Navy has done so far really capitalizes on what is available to them, but in the grand scheme of things, it doesn’t quite make it for what we need in terms of UHF,” Blaisdell, a retired Air Force major general, said in a May 6 interview.

“We’ve looked at all that, and I give them credit, but it’s nowhere near enough to handle the UHF crisis,” Blaisdell said. “If I were to look at it, in my opinion I would say that [the gap] adds up to at least one UFO satellite short and maybe more. And that’s if everything works right.”

Ratheon Network Centric Systems builds UHF communications payloads, most recently for an Optus Telecommunications satellite that was launched in 2003. The company could offer the U.S. government a similar payload that could be scaled anywhere from one to 20 channels, Blaisdell said. The government should invest in a UHF augmentation system that is equivalent to at least one and preferably four UFO satellites, he said.

There is very little the Navy can do to mitigate any UHF gap in the short term, but there is a need and an opportunity to develop this capability in the mid-term, said Tim Deaver, vice president of hosted payloads for SES World Skies U.S. Government Solutions.

“In the short term, it is what it is,” Deaver said in a May 6 e-mail. “There is only so much capacity available in space and there are a few things you can do to increase access during that period. We are focused on what we can do in the mid-term, adding UHF capacity on orbit. Through our proven commercial acquisition processes and reliable partners, we can have on-orbit capability inside of three years.”