“PTC.”
“Go.”
“Launch Vehicle Director.”
“Go.”
“Houston, this is Launch Control, we are go for launch.”
“Roger,” Mitch said, checking the countdown. “This is Flight, we are go for launch on schedule.”
“Roger that, Houston,” Launch Control said. “Launch on schedule.”
Once the clock reached −00:00:15, the television networks got what they were waiting for. The timer controller began the verbal countdown. “Fifteen,” she said, “fourteen… thirteen… twelve… eleven…”
Thousands had gathered at Cape Canaveral, the largest crowd ever to watch an unmanned launch. They listened to the timer controller’s voice as it echoed across the grandstands.
“…ten… nine… eight… seven…”
Rich Purnell, entrenched in his orbital calculations, had lost track of time. He didn’t notice when his coworkers migrated to the large meeting room where a TV had been set up. In the back of his mind, he thought the office was unusually quiet, but he gave it no further thought.
“…six… five… four…”
“Ignition sequence start.”
“…three… two… one…”
Clamps released, the booster rose amid a plume of smoke and fire, slowly at first, then racing ever faster. The assembled crowd cheered it on its way.
“…and liftoff of the Iris supply probe,” the timer controller said.
As the booster soared, Mitch had no time to watch the spectacle on the main screen. “Trim?” he called out.
“Trim’s good, Flight” was the immediate response.
“Course?” he asked.
“On course.”
“Altitude one thousand meters,” someone said.
“We’ve reached safe-abort,” another person called out, indicating that the ship could crash harmlessly into the Atlantic Ocean if necessary.
“Altitude fifteen hundred meters.”
“Pitch and roll maneuver commencing.”
“Getting a little shimmy, Flight.”
Mitch looked over to the ascent flight director. “Say again?”
“A slight shimmy. Onboard guidance is handling it.”
“Keep an eye on it,” Mitch said.
“Altitude twenty-five hundred meters.”
“Pitch and roll complete, twenty-two seconds till staging.”
WHEN DESIGNING Iris, JPL accounted for catastrophic landing failure. Rather than normal meal kits, most of the food was cubed protein bar material, which would still be edible even if Iris failed to deploy its tumble balloons and impacted at incredible speed.
Because Iris was an unmanned mission, there was no cap on acceleration. The contents of the probe endured forces no human could survive. But while NASA had tested the effects of extreme g-forces on protein cubes, they had not done so with a simultaneous lateral vibration. Had they been given more time, they would have.
The harmless shimmy, caused by a minor fuel mixture imbalance, rattled the payload. Iris, mounted firmly within the aeroshell atop the booster, held firm. The protein cubes inside Iris did not.
At the microscopic level, the protein cubes were solid food particles suspended in thick vegetable oil. The food particles compressed to less than half their original size, but the oil was barely affected at all. This changed the volume ratio of solid to liquid dramatically, which in turn made the aggregate act as a liquid. Known as “liquefaction,” this process transformed the protein cubes from a steady solid into a flowing sludge.
Stored in a compartment that originally had no leftover space, the now-compressed sludge had room to slosh.
The shimmy also caused an imbalanced load, forcing the sludge toward the edge of its compartment. This shift in weight only aggravated the larger problem, and the shimmy grew stronger.
“SHIMMY’S GETTING violent,” reported the ascent flight director.
“How violent?” Mitch said.
“More than we like,” he said. “But the accelerometers caught it and calculated the new center of mass. The guidance computer is adjusting the engines’ thrusts to counteract. We’re still good.”
“Keep me posted,” Mitch said.
“Thirteen seconds till staging.”
The unexpected weight shift had not spelled disaster. All systems were designed for worst-case scenarios; each did its job admirably. The ship continued toward orbit with only a minor course adjustment, implemented automatically by sophisticated software.
The first stage depleted its fuel, and the booster coasted for a fraction of a second as it jettisoned stage clamps via explosive bolts. The now-empty stage fell away from the craft as the second-stage engines prepared to ignite.
The brutal forces had disappeared. The protein sludge floated free in the container. Given two seconds, it would have re-expanded and solidified. But it was given only a quarter second.
As the second stage fired, the craft experienced a sudden jolt of immense force. No longer contending with the deadweight of the first stage, the acceleration was profound. The three hundred kilograms of sludge slammed into the back of its container. The point of impact was at the edge of Iris, nowhere near where the mass was expected to be.
Though Iris was held in place by five large bolts, the force was directed entirely to a single one. The bolt was designed to withstand immense forces; if necessary to carry the entire weight of the payload. But it was not designed to sustain a sudden impact from a loose three-hundred-kilogram mass.
The bolt sheared. The burden was then shifted to the remaining four bolts. The forceful impact having passed, their work was considerably easier than that of their fallen comrade.
Had the pad crew been given time to do normal inspections, they would have noticed the minor defect in one of the bolts. A defect that slightly weakened it, though it would not cause failure on a normal mission. Still, they would have swapped it out with a perfect replacement.
The off-center load presented unequal force to the four remaining bolts, the defective one bearing the brunt of it. Soon, it failed as well. From there, the other three failed in rapid succession.
Iris slipped from its supports in the aeroshell, slamming into the hull.
“WOAH!” EXCLAIMED the ascent flight director. “Flight, we’re getting a large precession!”
“What?” Mitch said as alerts beeped and lights flashed across all the consoles.
“Force on Iris is at seven g’s,” someone said.
“Intermittent signal loss,” called another voice.
“Ascent, what’s happening here?” Mitch demanded.
“All hell broke loose. It’s spinning on the long axis with a seventeen-degree precession.”
“How bad?”
“At least five rp’s, and falling off course.”
“Can you get it to orbit?”
“I can’t talk to it at all; signal failures left and right.”
“Comm!” Mitch shot to the communications director.
“Workin’ on it, Flight,” was the response. “There’s a problem with the onboard system.”
“Getting some major g’s inside, Flight.”
“Ground telemetry shows it two hundred meters low of target path.”
“We’ve lost readings on the probe, Flight.”
“Entirely lost the probe?” he asked.
“Affirm, Flight. Intermittent signal from the ship, but no probe.”
“Shit,” Mitch said. “It shook loose in the aeroshell.”
“It’s dreideling, Flight.”
“Can it limp to orbit?” Mitch said. “Even super-low EO? We might be able to—”
“Loss of signal, Flight.”
“LOS here, too.”