U.S. troops could begin receiving infrared data from a new space-based missile-warning sensor on a limited basis beginning late this summer, according to a U.S. Air Force official.


If all goes well during the trial period, which is expected to begin in August and run through the fall, the Space Based Infrared System (SBIRS) High sensor could be approved for full-time operational use in January or February, according to Col. Roger Teague, SBIRS wing commander at the Air Force Space and Missile Systems Center in Los Angeles.


The trial period is intended to give troops a chance to use the sensor and
that needs to be tweaked before the sensor
is approved for full-time use, Teague said in a May 19 interview.

The SBIRS sensor is hosted on a classified spacecraft in a highly elliptical orbit. The Air Force did not announce its launch due to the sensitivity of details about the host spacecraft. Air Force officials did acknowledge in November 2006 that the payload was in space. Teague said the SBIRS payload has been meeting or exceeding its requirements during testing thus far, but declined to discuss specific details of its performance.

Teague acknowledged that the time between launch and going into operational mode for the first SBIRS payload is longer than the typical check-out period that satellites go through following launch. However, he said that a missile-warning sensor takes longer to calibrate than many other types of payloads, and
that subsequent payloads in the SBIRS constellation
likely would take less time to check out before being certified as operational assets.


The SBIRS payload on orbit today is expected to be joined by another payload in highly elliptical orbit at a date that has not been disclosed because its host spacecraft
also will be classified. The Air Force currently anticipates buying a total of four payloads for highly elliptical orbit, and at least four dedicated geosynchronous-orbiting satellites.


Work on the first geosynchronous spacecraft is proceeding well as the program office works with prime contractor Lockheed Martin Space Systems of Sunnyvale, Calif., to recover from flight software problems that cropped up in January 2007, Teague said.


Jeff Smith, Lockheed Martin’s SBIRS vice president and program manager, said during the May 19 interview that the company had delivered the first batch of new flight software over the previous weekend, which includes around 25,000 lines of code. The software will be used to test command and telemetry functions for the SBIRS satellites on flight-equivalent hardware, which is considered an important step toward integration and testing with the first satellite scheduled for late 2008, according to a written statement
by Lockheed Martin spokesman Steve Tatum.


The first block of software
also will be integrated into a simulation intended to address space-to-ground interfaces, according to the statement. The remainder of the new software package is expected to be ready Aug. 28, Smith said.

The second block includes about 35,000 lines of code,
applications that control electrical power, temperature, attitude and navigation on the SBIRS geosynchronous satellites. The second block also includes
a redesigned fault management system that responds when an anomaly is detected during on-orbit operations and places the satellite into a safe state while operators on the ground analyze the situation and take corrective action, according to the Lockheed Martin statement.


Smith said
he and Teague are conducting daily reviews with the government and industry program staff to pour over every aspect of the work on the first geostationary spacecraft as they prepare for launch in December 2009.

Teague and Smith both described the remaining work on the first satellite as challenging, but expressed confidence in their ability to meet the launch date. In the meantime, the current missile warning constellation, known as the Defense Support Program, is as “healthy as it’s ever
been,” Teague said.