Forbes:
The most important program the Pentagon has for assuring early warning of a missile attack is the Space Based Infrared System, or SBIRS (“Sibbers”). SBIRS is a constellation of four satellites parked in geosynchronous orbit above the equator, plus two additional sensors hosted on spy satellites that fly over the North Pole. Collectively, the constellation has a continuous view of the Earth’s entire surface, which it searches for signs of infrared radiation indicating major heat sources – such as missile launches. The geosynchronous satellites have both scanning sensors for wide-area searches and staring sensors for focusing in on smaller areas of high interest.
If Russia or any other country were to launch a ballistic missile, SBIRS would be the first U.S. military asset to see it. The satellites would quickly process that information and transmit it via a secure communication link to elements of the Air Force Space Command in Colorado, from whence it would then be shared — very quickly – with the North American Aerospace Defense Command (NORAD) and other relevant parts of the military. If the launch in question is deemed to be non-threatening, then it will simply be monitored. But if it is an attack, the president will be notified within minutes of detection. He will then decide in consultation with his military advisors how to respond, using a menu of pre-selected retaliatory options.
The first SBIRS geosynchronous satellite launches into orbit on an Atlas V launch vehicle in 2011. The hot exhaust gasses from the launch vehicle demonstrate why it isn’t hard for the satellites to quickly identify a hostile missile launch. However, SBIRS is capable of detecting and characterizing a wide array of less energetic infrared phenomena. (Retrieved from Flickr)
The first SBIRS geosynchronous satellite launches into orbit on an Atlas V vehicle in 2011. The hot exhaust gasses from the vehicle demonstrate why it isn’t hard for the satellites to quickly identify a hostile missile launch. However, SBIRS is also capable of detecting and characterizing a wide array of less energetic infrared phenomena. (Retrieved from Flickr)
The Pentagon has spent hundreds of billions of dollars over the years preparing for the day when such a threat arises, so that no nuclear aggressor will ever be able to devise a way of escaping retribution. It has a “triad” of offensive weapons — bombers, missiles in silos, missiles at sea — that would be nearly impossible to destroy in a surprise attack. It has redundant command networks for staying in touch with them. It has spy satellites that eavesdrop on potential adversaries from antennas the size of football fields, or collect imagery that can capture details as small as four inches. But without SBIRS, the whole edifice of nuclear deterrence might crumble in a crisis. So it matters a lot that the constellation be in good working order 24-7.
That’s the responsibility of the Remote Sensing Systems Directorate, a part of the Air Force’s Space and Missile Systems Center at Los Angeles Air Force Base — traditionally the hub of the U.S. military-industrial complex for space. Antecedents of the directorate have been in this line of work since shortly after the Russians launched Sputnik in 1957. The first of twelve Missile Defense Alarm System (MIDAS) satellites were launched in 1960, followed ten years later by the constellation that preceded SBIRS called the Defense Support Program. The 23rd and final satellite in the latter program was launched in 2007, by which time SBIRS had been in development for 11 years. But the SBIRS program only became fully operational two years ago.
One reason SBIRS took so long to bring to fruition — 15 years from initial award to full operational status — was that it was conceived to be far more capable than previous missile warning systems. Its infrared sensors have three times the sensitivity of those in the legacy constellation, and twice the “revisit” rate as they scan the Earth’s surface. They also operate in multiple infrared wavelengths, enabling them to detect and characterize a wider range of infrared phenomena. The pointing accuracy of each five-ton geosynchronous satellite is said to be 0.05 degrees, thanks to three-axis stabilization, and the nominal design life of each spacecraft is 12 years (they will last longer if fuel holds out)…
