WASHINGTON — The U.S. Navy has issued a final request for proposals to build an Ultra-High Frequency (UHF) communications payload that will launch aboard a commercial communications satellite around 2012 to mitigate a potential gap in coverage.

Meanwhile, the Australian military is pursuing a similar procurement, according to industry sources.

The Navy is concerned its current UHF satellite communications capabilities — primarily the UHF Follow-On constellation — are deteriorating and may not provide adequate service until the next-generation Mobile User Objective System constellation is operational.

The Navy intends to award a single firm fixed-price contract this summer valued at $6 million in 2009 and $35 million in 2010, according to the request for proposals. The money will be awarded in increments based on the contractor successfully completing a series of milestones, the last of which will be on-orbit check out of the UHF payload. The contract also will include 10 one-year options for service on as many as eight UHF channels, the pricing for which has not yet been determined.

The Navy’s location preferences are slots covering the Indian Ocean region, continental United States or Atlantic Ocean, in that order, the documents show. The Navy in making its decision will take into consideration the price of each bid, which will be weighted roughly equivalent to the combination of other factors including performance, past performance and small business.

The release of the final request for proposals was five months later than the Navy had originally planned. Steve Davis, spokesman for the Space and Naval Warfare Systems Center in San Diego, which is managing the program, would not provide an explanation for the delay.

The UHF frequency is prized for its ability to reach users operating under jungle canopies and those on the move with small antenna systems. Dave Russell, strategic satellite operations branch chief at U.S. Strategic Command’s Joint Task Force for Global Network Operations, ArlingtonVa., said in a set of briefing charts from May 2008 that senior U.S. government officials, including the president and the secretary of defense, use UHF satellite communications on a daily basis. Other users include homeland security officials, combat search and rescue teams and operations forces engaged in both open and covert combat actions, according to the charts.

Demand for the UHF bandwidth has increased dramatically in recent years. Russell’s charts indicate that 15 years ago, the military had no more than 10,000 UHF terminals, and the user community largely was limited to Navy personnel, special operations forces and senior decision makers. The military may have as many as 40,000 UHF terminals today, according to the charts.

A significant portion of the military’s UHF Follow-On satellites are single-string fault tolerant, meaning that loss of a single component could trigger failure, and even minor issues could translate to loss of capacity or shortened operational lifetime, according to the charts. The charts note that there is a “high probability of additional losses” before the first Lockheed Martin-built Mobile User Objective System satellite becomes operational in 2010. Hosted payloads could help mitigate the impact of constellation degradation until the full Mobile User Objective System constellation begins operations, according to the charts.

While the U.S. government in the past had been reticent to rely on commercial satellites to host payloads, recent years have given commercial operators reason to believe payload hosting could become the norm rather than the exception. Commercial operator Intelsat of Bermuda and Washington has led the way, launching in 2005 an L-band payload for the U.S. Federal Aviation Administration aboard its Galaxy 15 satellite. The company also signed a deal in April 2007 with U.S. Strategic Command to launch a so-called Internet Router in Space demonstration payload aboard the Intelsat-14 satellite in mid-2009.

Americom Government Services (AGS) of McLeanVa., inked its first hosted payload deal in 2008, a $65 million contract with the U.S. Air Force Space and Missile Systems Center to host an experimental missile warning sensor aboard an Orbital Sciences-built communications satellite that will launch in 2010. AGS is a subsidiary of SES Americom, which is owned by satellite operator SES of Luxembourg. Both Intelsat and SES have future satellites in the pipeline capable of hosting government payloads, representatives from each company have said.