It was a relatively low-tech device that issued a warning on that Wednesday afternoon, a device that had gone all but unused for years. In an effort to increase the number of nuclear detection devices in orbit without increasing the actual number of satellites, in the late 1970s and early 1980s a secret program code-named FOREST GREEN was implemented. NAVSTAR Global Positioning System navigation satellites were fitted with electromagnetic pulse sensors and devices called (quite appropriately for nuclear detonation detection) Bhangmeters, which were sensitive optical flash detectors that could determine the explosive yield of a nuclear explosion by the brightness of the flash. Unlike AMWS, which were used only on specific (albeit very wide) areas of the Earth, FOREST GREEN had global coverage because the eighteen-satellite NAVSTAR constellation had at least three satellites looking at every piece of the Earth at every moment.
A nuclear explosion has a definite pattern of two pulses — the first less intense than the second — caused first by the detonation of the triggering device, followed exactly one- third of a second later by the main explosion; this was the reason Bhangmeters were mounted in pairs, with one more sensitive than the other. The EMP detectors on the three FOREST GREEN satellites also registered the disruption of the ionosphere before communication between the satellites and their receivers on Earth were abruptly cut off.
The senior controller in the Operations Center, an Air Force colonel named Randolph, immediately put the staff sergeant’s console display up on the “big board,” a rectangle of six 2-by-3-foot screens in the front of the Operations Center. The display was relatively uninformative at this point — three lines out of eighteen on the display were flashing, with a string of numbers showing the system readings and the threshold levels pre-programmed into the system.
“All stations, this is Randolph. I confirm a FOREST GREEN event detection and classification, I need a status check and report in thirty seconds, all stations stand by.”
The problem with the FOREST GREEN sensors was that they were not highly directional — the sensors could accurately record a nuclear detonation but not precisely pinpoint the explosion’s location; when the Bhangmeters were installed on older Vela nuclear-detection satellites, the device’s telescopic eye could pinpoint the location of the detonation, but on NAVSTAR satellites the sensors were relegated to area reports only. In a few moments Amy Hector had replaced the cryptic lines of data with a graphic pictorial of the information: a chart of the Earth that was within line-of- sight reach of the three NAVSTAR satellites that had suddenly gone off the air. Somewhere within the three overlapping shaded spheres, the first above-ground nuclear device in thirty years had detonated.
Unfortunately, the display showed the explosion could have occurred anywhere from Hawaii to Thailand and from
Japan to Australia. “I need better information than that,” Colonel Randolph said. “Find out why no DSP systems issued an alert.”
DSP was a constellation of satellites so sensitive that they could detect brush fires, structure fires, or even high-performance aircraft using afterburners — all from twenty-two thousand miles in space.
“Sir, this is Staff Sergeant Hector on FOREST GREEN,” Hector interjected. “I think I can come up with a rough triangulation.”
“Let’s have it, Sergeant.”
“I’ve got the exact time when aft three of the NAVSTAR satellites shut down,” Hector explained, “and I’ve got the time down to one-one-hundredth of a second. I can—”
Randolph looked at her. “I get the picture, Sergeant Hector. Speed of gamma particle versus time. Are the off-air times that different?”
“Stand by, sir.” There was a slight pause, then Hector replied: “Two times are the same; the other is different. I can poll the sensor threshold-release circuits and get a more exact time; I can also try a laser orbital velocity measurement to see if the event changed the orbits—”
“Just do it, Amy.” This was the first time he had ever recalled calling Hector by her first name, but it seemed oddly appropriate now. “But first, I need an acknowledgment of a suspected FOREST GREEN event from CINCSPACE- COM right away — also get SAC and JCS on the line.”
“Yes, sir.”
“NORAD hasn’t issued an alert yet,” Randolph muttered half-aloud. “Why the hell haven’t they said anything? Something big enough to knock out three satellites is not good news…”
Jon Masters had his feet up on the bulkhead, was on his third plastic squeeze bottle of Pepsi and halfway through a bologna and cheese sandwich when the toneless, emotionless voice of the Air Force mission control tracking officer on the radio said, “Masters One, College, contact lost with Jackson One.”
