The tip of the Falcon 9 first stage core caught the last light of the sun as it sank below the Texas horizon. From the tip, one could see the lights of McGregor easily, and on the horizon the barely-visible lights of Waco. None, of course, held a candle to the one SpaceX was working to light here. This wasn’t the first Falcon 9 core they had fired, but it was instrumented heavily nonetheless--this would, if all went well, be the first to fly, and that meant extra data that was needed by NASA’s evaluations and by SpaceX’s own engineers back in Hawthorne. Sensors fed trail of wires down the side of the booster, held on every few meters with blue tape, The work they were doing hadn’t sprung from nothing, however--it built on the foundations of much of what had gone before. This 9-engine test of the first flight Falcon 9 built on the previous tests of qualification tanks and stages, and the single Merlin 1 had already been proven on Falcon 1 flights--indeed, the Falcon 9 engine section was massively overbuilt to allow them to us essentially the same actuator assembly as already used for the Falcon 1.
It wasn’t even just the Falcon foundations that this test built on: the test site and many of its structures and blockhouses dated back to the WWII Bluebonnet Ordnance Plant, then leveraged the grounds and facilities designed to be far from anything worthwhile in case of an explosion into a history of other applications. The core itself now rested on one of those foundations--the massive main vertical test stand, a giant blue tripod rising almost the core’s own height above the ground, the legacy of a Beal Aerospace engineer who had at some point calculated that it was cheaper and more effective to build a test stand far enough in the air to not need to dig a flame trench or a flame bucket than to build a traditional test stand. As the core test counted down and the sun-lit portion of the booster tracked ever higher towards its tip, nearly 140 meters above the ground, the steady boiloff from the tanks cut out as the stage began to build to flight pressure. McGregor’s residents were about to once again face the results of that decision by some unknown Beal Aerospace engineer, for while Beal hadn’t gotten a core in condition to use their large tripod stand, SpaceX now had, and thus McGregor got to appreciate that mounting the engines of the stage 70 meters above the ground gave acoustic waves from test firings near-direct line of propagation to the town itself.
While single engine Merlin tests were barely audible, not even the fountain of water which created an artificial Niagara at the top of the trip wrapping around the base of the tanks could prevent the fury of the nine Merlin engines from creating a roar which could be heard almost as far as Waco. The engineers in the blockhouse waited out the final seconds, then with a rush of white rising to a roar of flame with a brief moment of green TEA-TEB flash, the core was lit. In town, at least a few residents stopped what they were doing to look once again to the southwest. Alerted to be ready by the warnings of “louder than usual” rocket tests that always preceded uses of the tripod stand, at least one quickly tapped a stopwatch on their wristwatch, counting off the runtime of two or so minutes. When the roar from the distance stopped, leaving only the towering plume of smoke illuminated into a glow by the setting sun, one went in after a camera to post a picture and the runtime to the internet. Almost before the test results and data could be packaged and sent to Hawthorne, armchair engineers of all sorts of experience levels would be trying to read tea leaves into the sounds overheard on a clear, warm summer afternoon in Texas. The first flight core was through testing. The first flight second stage was to soon follow--the planning charts had it shipping to Texas from California by the end of the year--and with that done nothing would be between them and a maiden launch except the tiresome work of putting the vehicle together and testing it.
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While the sun was setting on McGregor, it was rising high into the sky over Woomera, 17 hours ahead. The weather was as inconsistent as could have been expected from an Australian spring. The morning of September 29th when they’d rolled out the first stack on the transporter-erector, it’d been barely 9 Celsius in the morning, then peaked at 25C. The 30th had been hot, though, one of the first properly hot days of spring. It’d bounced between comfortable and the cool side of warm--particularly up on steel towers above the desert, 30 Celsius wasn’t particularly comfortable. Sweat had soaked fall harnesses as they worked, checking hoses and electrical lines. All of yesterday, while SpaceX had been preparing their tests in McGregor, the temperature had only slowly bled off the heat.
Today it was chilly again, a fact appreciated by the tank technicians as their chillers worked to pull enthalpy out of the kerosene and liquid oxygen, cooling the propellants ahead of the first full wet dress rehearsal for the K-1 program. It might have been a decade late, but for the first time the Woomera launch site was active and the launch mount was taking up the load of a filling K-1 stack. Preparations had begun around 9 in the morning, as small amounts of propellants had begun to circulate through the vehicle and its engines to begin chilling them down to the bitterly cold temperatures of densified propellants needed for the K-1’s high performance Russian engines. To minimize the time allowed for the sun to warm the tanks, the propellants didn’t begin loading until just two hours before the start of the test window. Now, the tanks were full, and the vehicle and the control staff were running through the full sequence of test preparations. While the propellants flowed out of the tank farm, through feed lines, up the transporter-erector, and into the vehicle, radar systems were brought online and traversed, the communications links to flight control in Oklahoma were tested, and the launch team settled in for a dress rehearsal of every flight event short of actual ignition, a fact repeatedly confirmed, as the test director in Oklahoma City, Jean-Pierre Boisvert, would call over the communications loop, “Flight enable to inhibit,” to be confirmed by one of the Woomera avionics engineers as “Confirmed, flight enable inhibited.” The clock ticked down, sensors monitoring hundreds and even thousands of values--the flow rates through valves, the temperatures inside and outside the vehicle, the pressure of the LAP and OV kerosene and oxygen supplies, the pressurization levels of the ethanol and helium for the OV’s orbital maneuvering engines, and the state values of hundreds of variables and flags inside the complex weave making up the flight control avionics. The engines were traversed, confirming the functionality of the thrust vector control gimbals for both the LAP’s twin AJ-26-58 engines outboard and the center restartable AJ-26-59 and the OV’s vacuum-optimized AJ-26-60. All was going well as the final minute counted down.
Within the last few seconds, the wet dress rehearsal proved its value as a stress-test on the vehicle and pad systems. As the water deluge system on the pad came on, adding a shroud of spray to the small billows of cloud from the engine cryo purge, the dreaded call came over the loop: “HOLD, HOLD, HOLD!” The results were an anticlimax, as they looked much like a successful wet dress rehearsal: the tanks were cycled, the cryogenic propellants once again billowing from boil-off relief valves as operators dumped the flight pressure, the flow of sound damping water and engine cooling propellants cutting off. Boisvert, half a world away from the team in Woomera, leaned back. It’d been too much to hope for that they’d get a successful test on the first run, but getting so close before failing was in some ways as frustrating as if they had hit a hold during main propellant fill. His team began to set the propellants from the vehicle to flow back to the the main storage tanks--the capacity of the chillers and the tanks for the super-cooled propellants was the main limit on the number of times they could attempt a WDR or a flight in a single day, regardless of length of the test or launch window. Finally, any hope of a quick turnaround was halted--the problem wasn’t with the vehicle at all, but with the water deluge: a valve on the high-pressure mains feeding the deluge had failed due to the circulating cryogenic boil-off from the engines in the vicinity, and needed to be replaced. It was as close to a successful first test as he could have hoped for--the vehicle was almost ready, but the ground support systems had failed. Still, it meant a stand-down for the day. While Boisvert and the North American team stood down from the test, Woomera’s engineers and technicians, ATK contractors and RPK employees alike, continued the work to safe the vehicle to be able to service the pad. They would simply have to keep trying until they got it right. Fortunately, they had three months until the end of the year.