After two scrubbed attempts earlier in March, firstly on the 8th following a nagging issue pertaining to thermal conditioning of its Liquid Natural Gas (LNG) and Liquid Oxygen (LOX) propellants and secondly on the 11th with a nail-biting last-second engine shutdown and recycle on the pad, Relativity Space successfully launched its 3D-printed Terran-1 rocket on Wednesday night. The vehicle passed flawlessly through “Max Q”, the period of peak aerodynamic turbulence at T+80 seconds, although an anomaly with the second stage—declared by the Launch Director at T+5 minutes—prevented the vehicle from achieving orbit. Liftoff of the 110-foot-tall (33.5-meter) rocket occurred at 11:25 p.m. EDT from Launch Complex (LC)-16 at Cape Canaveral Space Force Station, Fla.
“Today’s launch proved Relativity’s 3D-printed rocket technologies that will enable our next vehicle, Terran-R,” Relativity tweeted. “We successfully made it through Max Q, the highest-stress state on our printed structures. This is the biggest proof point of our novel additive manufacturing approach.
“Today is a huge win, with many historic firsts,” it added. “We also progressed through Main Engine Cutoff and Stage Separation. We will assess flight data and provide public updates over the coming days.”
Relativity Space, founded back in 2015 by aerospace engineers Tim Ellis and Jordan Noone—formerly of Blue Origin and SpaceX, respectively—is based out of Long Beach, Calif., and seeks to develop a fleet of orbital-class launch vehicles, produced almost entirely through additive manufacturing. Via its in-house-designed Stargate system, about 85 percent of the total mass of the two-stage Terran-1 rocket is 3D-printed, as Relativity aims to build entire boosters, priced as little as $12 million, in under 60 days.
Although the first Terran-1 mission ferried no payload uphill, it did carry a 3D-printed piece from the Stargate printer, measuring 6.5 inches (16.5 centimeters) across and weighing in the region of 3 pounds (1.4 kilograms). But as outlined in AmericaSpace’s Terran-1 pre-launch story, the rocket’s capacity to lift 2,750 pounds (1,250 kilograms) to a low-Earth orbit of 115 miles (185 kilometers) and up to 1,500 pounds (700 kilograms) to a Sun-synchronous orbit of 750 miles (1,200 kilometers) has already won it a burgeoning commercial clientele, ranging from Telesat to Momentus and from Iridium to Spaceflight, Inc.
After the Terran-1 flight hardware arrived at the Cape last June, it was put through an intensive regime of spin-start tests of its nine Aeon-1 first-stage engines, with a Federal Aviation Administration (FAA) license initially covering July through December for its inaugural launch attempt. But the need for additional hot-fire tests, Eastern Range issues and last September’s onslaught of Hurricane Ian pushed the mission deep into the fall and eventually into the spring of 2023.
Yet for a mission with the uplifting moniker of “Good Luck, Have Fun”, Terran-1’s opening pair of launch attempts provided neither. But they have certainly afforded Relativity a wealth of experience and a fair share of drama.
On 8 March, despite picture-perfect weather conditions along the Space Coast, the first try was scrubbed when an issue arose with thermal conditioning of the rocket’s load of Liquid Natural Gas (LNG) and Liquid Oxygen (LOX). Engineers successfully pressed towards the Terminal Count, establishing Terran-1’s propellant tanks at flight pressures, priming the nine Aeon-1 first-stage engines for ignition and beginning the retraction of the Transporter-Erector (TE) “strongback”.
But Attempt No. 1 ultimately came to nought when an autonomous abort was called at T-70 seconds, just as Terran-1’s on-board computer prepared to assume primary command of all vehicle critical functions. “Today’s launch attempt…was scrubbed due to exceeding Launch Commit Criteria (LCC) limits for propellant thermal conditions on Stage 2,” Relativity later tweeted, with subsequent updates imposing blame upon a malfunctioning Ground Support Equipment (GSE) valve.
Attempt No. 2 on 11 March went right down to (and beyond) the wire. Teams elected to move their targeted T-0 deep into the three-hour “launch window”, on account of iffy upper-level winds at the Cape.
Clocks later halted at T-70 seconds, when an unauthorized boat strayed into the launch danger area. But a second effort to get the mission off the ground saw Terran-1’s nine Aeon-1 engines roar to life at T-6 seconds and burn furiously with their characteristically eerie blue-hued exhaust.
Then, with nail-biting suddenness, the engines shut down at T-0.5 seconds, leaving the 15-story booster sitting motionless, surrounded by a pall of smoke on the pad. The countdown clock displayed an ominous 00:00:00, with the hold having been autonomously commanded just prior to TE retraction and liftoff.
Astonishingly, the Relativity team recycled clocks and went for another try, right at the end of the window, but it was not to be. Another autonomous hold came at T-45 seconds and with no remaining margin in the launch window, inevitably, the second attempt to get Terran-1 airborne was called off.
Last weekend, Relativity announced its intent to target a new launch window which extends from 10 p.m. EDT Wednesday through 1 a.m. EDT Thursday, promising an impressive view for skywatchers. “Nighttime skies,” the organization tweeted, “mean very cool methane rocket engine plumes.”
Weather conditions for Wednesday night’s launch attempt were expected to be highly favorable, with the 45th Weather Squadron at Patrick Space Force Base predicting a 95-percent likelihood that Mother Nature would be smiling. Only a slight risk of violating the Cumulus Cloud Rule stood in Relativity’s way, at least from a weather perspective.
“Favorable weather looks to be in place for the launch attempt Wednesday night,” noted the 45th in its L-1 update on Tuesday. “Expect partly cloudy skies in the area, so there is a slight concern for the Cumulus Cloud Rule, but the overall coverage should diminish through the late afternoon and early evening hours tomorrow.”
Following an initial move of the targeted T-0 to 10:38 p.m. EDT, a hold was called at T-25 minutes due to a vessel in the launch danger area. This was the second time that Relativity has been faced with the need to shoo away an unauthorized intruder, just prior to a launch attempt.
Clocks continued counting to T-10 minutes, where a further hold was called to await further data on strong upper-level winds, with revised T-0 points at 11:05 p.m. EDT and finally 11:25 p.m. EDT. At T-45 seconds, the Launch Director gave a definitive “Go for Launch”.
Six seconds prior to liftoff, the nine Aeon-1 engines at the base of Terran-1’s first stage roared to life, burning furiously with a propulsive yield of 207,000 pounds (95,000 kilograms) and their peculiar, blue-hued exhaust. As the countdown clock touched zero, the vehicle departed LC-16, marking its first launch in 35 years.
The pad previously saw Titan and Pershing-class short-range and medium-range ballistic missiles test-fired on 141 occasions between December 1959 and March 1988. It was retired following the Intermediate Range Nuclear Forces Treaty between the United States and the Soviet Union, but gained a new lease of life when Relativity secured a Right of Entry from the 45th Space Wing to use LC-16 in January 2019.
Powering uphill under the power of her nine flaring Aeon-1s for the opening 2.5 minutes of flight, Terran-1 passed “Max Q”, the point of peak aerodynamic turbulence on the vehicle, at 80 seconds and traveling at a velocity of some 1,100 mph (1,800 km/h). Main Engine Cutoff (MECO) occurred at 160 seconds, followed by the separation of the first stage.
The turn then came for the ignition of the single vacuum-optimized Aeon-1 engine of the rocket’s second stage, which was meant to come alive with a thrust of 28,000 pounds (12,700 kilograms) and execute a lengthy “burn”, lasting more than five minutes, ahead of Second Engine Cutoff (SECO) at T+463 seconds.
But it did not happen. Despite spectacular views of the vacuum-optimized Aeon-1, no ignition took place and after several minutes of ominous silence the Launch Director declared a “T-plus Anomaly with Stage 2”. However, a successful first-stage ascent and notably a safe passage through the highly stressful Max Q regime has turned this launch into something of a “Successful Failure” for Relativity.
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And there we have a day in the life of rocket science. Never easy. Never cheap. Never guaranteed. The only way to find out if it will work is to build it and find out if it will work.