WASHINGTON — The U.S. Air Force, which is developing an experimental tactical missile warning sensor slated for launch late next year, has unveiled tentative plans to follow that up with a strategic sensor demo that would launch in 2019 or 2020.

The experimental staring sensor would provide near-immediate notification of strategic missile launches, the Air Force said in documents accompanying its 2016 budget request. Whether the service moves ahead with the demonstration will depend on the recommendations from an ongoing analysis of alternatives for its future missile warning satellite constellation, the documents said.

The Air Force’s current-generation missile warning constellation, known as the Space Based Infrared System, ultimately will consist of four satellites in geosynchronous orbit and infrared sensors hosted aboard two classified satellites in highly elliptical orbit. The geosynchronous satellites carry scanning sensors that cover large areas and staring sensors that focus on smaller swaths of territory to provide more-immediate warnings of launches.

Although the Air Force is still launching SBIRS satellites, it is in the midst of an analysis of alternatives for what comes next. One possibility is to assign the strategic and tactical warning missions to separate satellites, a scheme that fits with the so-called disaggregation model that the Air Force is exploring for several of its space capabilities.

Sources said it does not appear to be the so-called 9-degree wide-field-of-view sensor that was the subject of some Air Force design work before being dropped last year.

The first two geosynchronous SBIRS satellites are on orbit, with the next two slated to launch in 2016 and 2017, budget documents show. The fifth and sixth satellites, which will replenish the constellation, are on order from SBIRS prime contractor Lockheed Martin Space Systems of Sunnyvale, California.

Beyond that, according to budget documents, the service is looking at four broad options: continuing with the current SBIRS design, evolutionary upgrades, a combination of new and evolved systems, and an “alternative architecture” that could involve disaggregation.

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In parallel, the Air Force is experimenting with alternative sensor technologies. In 2011, for example, the service launched the Commercially Hosted Infrared Payload experiment aboard a communications satellite. The service wrapped up its experiments with that sensor last year.

This past June, the service awarded a $13 million contract to a division of New York-based defense conglomerate L-3 Communications to develop a 6-degree-field-of-view sensor, which is slated to launch at the end of next year and focus on tactical missile threats. Millennium Space Systems of Torrance, California is building the space vehicle, which is expected have a design life of three to five years, according to the Federal Business Opportunities website.

In its 2016 budget request, the Air Force is seeking $11 million for delivery, calibration and on-orbit checkout of the 6-degree sensor, along with work on associated ground systems. The service is seeking another $40 million to support the integration of the payload to the spacecraft and then to the launch vehicle.

Air Force documents posted in January on the Federal Business Opportunities website suggest that commercial satellite manufacturer Space Systems/Loral of Palo Alto, California, will be tapped to arrange for the launch of the satellite to a near-geosynchronous orbit as a secondary payload. However, that notice was canceled shortly after being published.

Efforts to explore alternative technologies and approaches to missile warning, funded under the SBIRS Space Modernization Initiative, have been a tough sell to lawmakers, especially in the House. In 2015, for example, Congress gave the sensor testbed program $10 million less than the Air Force requested.

Air Force officials have said the experiments with wide-field-of-view sensors are critical for two reasons. First, they help test and verify architectures for a SBIRS follow-on program. Second, they will help the Air Force develop the algorithms necessary to process the reams of data that would come from improved sensor focal-plane technology.


Mike Gruss covers military space issues, including the U.S. Air Force and Missile Defense Agency, for SpaceNews. He is a graduate of Miami University in Oxford, Ohio.