After greater than six many years of operational service, 388 flights launched since Could 1960 and a formidable 95-percent success fee, the ultimate curtain-call for the Delta Program should await one other day as United Launch Alliance (ULA) scrubbed its first try and get the final Delta IV Heavy rocket airborne. Regardless of solely 30-percent-favorable climate odds, the countdown proceeded previous the ultimate built-in maintain at T-4 minutes, solely to be halted in an ominous “Maintain, Maintain, Maintain” name a few seconds later. Groups will realign for a backup “launch window” that opens at 1:37 p.m. EDT Friday.
Styled by ULA as its “Most Metallic” of rockets, the triple-barreled Delta IV Heavy was till February 2018 the world’s strongest in-service operational launch car, its three Widespread Booster Cores (CBCs)—every outfitted with a single Aerojet Rocketdyne-built RD-68A engine—producing a liftoff yield of two.1 million kilos (1 million kilograms). The triple-barreled behemoth entered service in December 2004 and with NROL-70 has logged 16 launches, delivering 12 NRO payloads, the ultimate Protection Help Program (DSP) early-warning satellite tv for pc in November 2007, the Exploration Flight Take a look at (EFT-1) of NASA’s Orion spacecraft in December 2014 and the Parker Photo voltaic Probe in August 2018.
Main payload for the Heavy’s ultimate voyage was NROL-70, the fifth and final mission under a $1.18 billion Launch Operations Support (LOPS) contract modification awarded by the Space and Missile Systems Center (SMC), in partnership with the NRO, to ULA in September 2019. The contract adopted on the heels of an earlier Launch Car Manufacturing Providers (LVPS) contract awarded in October 2018 for a bunch of extremely labeled NRO payloads devoted to nationwide safety: the many-times-delayed NROL-44, which lastly flew in December 2020, NROL-82, launched in April 2021, NROL-91 in September 2022—the ultimate Delta IV Heavy launch out of Vandenberg Area Power Base, Calif.—and most not too long ago final June’s NROL-68 from the Area Coast.
Delta IV Heavy {hardware} for NROL-70 started arriving on the Cape in Could of final yr, when the 134-foot-long (40.8-meter) middle, port and starboard Widespread Booster Cores (CBCs) have been delivered from ULA’s Decatur, Ala., manufacturing facility to the wharf at Port Canaveral, aboard the R/S RocketShip vessel. Over the subsequent a number of months, the middle core was mated with the port and starboard CBCs, adopted by the 45-foot-long (13.7-meter) Delta Cryogenic Second Stage (DCSS), contained in the Horizontal Integration Facility (HIF). Additionally accomplished within the HIF, the Launch Mate Unit (LMU) was mounted to the three CBCs to function a structural base when it stands atop SLC-37B’s launch desk.
Final 19 December, the 170-foot-long (51.8-meter) built-in CBC/DCSS stack—minus its payload fairing—was transferred horizontally through a 36-wheeled, diesel-powered transporter from the HIF to the pad. It was raised vertical the subsequent day as a part of the Launch Car On Stand (LVOS) milestone and on 26 February the 65-foot-long (19.8-meter) “trisector” Payload Fairing (PLF) which encapsulates the NROL-70 spacecraft was added, topping-out the stack at 235 toes (72 meters) excessive.
On Sunday, ULA and the NRO collectively introduced on X that groups have been focusing on at T-0 level at 1:40 p.m. EDT Thursday. And on Wednesday, key personnel gathered in ULA’s Delta Operations Middle (DOC) on the Cape for the Launch Readiness Overview (LRR), polling a unanimous “Prepared” to proceed and signing the Launch Readiness Certificates.
The NROL-70 countdown operation started crisply at 5:10 a.m. EDT, at T-8 hours, with the powering-up of the rocket, testing of its steerage system and flight management checkouts forward of fueling. The 330-foot-tall (100-meter) Cell Service Tower (MST) started its quarter-mile-per-hour (0.4 km/h) rollback to reveal the Delta IV Heavy at 6:09 a.m. EDT and reached its “hard-down” level, a couple of soccer subject’s distance away from the rocket, by 6:52 a.m. EDT.
Led by Launch Conductor Scott Barney and Launch Director Tom Heter III, authorization was granted at 9:30 a.m. EDT to load the rocket with 330,000 gallons (1.2 million liters) of liquid hydrogen, chilled to -252 levels Celsius (-423 levels Fahrenheit) and 120,000 gallons (450,000 liters) of liquid oxygen, cooled to -183 levels Celsius (-298 levels Fahrenheit). Because the countdown resumed from its first built-in maintain, groups pressurized the liquid hydrogen storage tanks and charged high-pressure helium bottles on the primary and second phases and cryogenic fueling commenced.
By 11 a.m. EDT, the tempo of tanking picked up as propellant circulation transitioned from a slow-fill to a fast-fill regime. Shortly afterwards, as groups began loading 6,000 gallons (27,000 liters) of liquid oxygen and 10,000 gallons (45,500 liters) of liquid hydrogen into the DCSS higher stage, ULA revealed—with out elaboration—that it was monitoring in the direction of a barely later T-0 level of two:03 p.m. EDT, a goal subsequently adjusted nonetheless additional to the proper to 2:45 p.m. EDT.
“The launch forecast stays at a 30-percent probability of allowable liftoff situations, as a result of sturdy winds from the passage of a chilly entrance,” ULA famous. “The outlook consists of some scattered clouds, good visibility, northwesterly winds 25-30 knots and a temperature within the low 70s Fahrenheit.”
Passing 12 midday EDT, climate was nonetheless trending “Pink” (“No-Go”), as a chilly entrance moved rapidly over the Cape and threatened violations of guidelines pertaining to cumulus clouds, disturbed climate and flight by precipitation. All Delta IV Heavy and ground-side methods have been “Inexperienced” (“Go”) however at 12:47 p.m. EDT ULA declared that climate had moved to “Inexperienced”, though Launch Climate Officer Mark Burger reported that situations remained near the edge for acceptable standards.
Mr. Barney led a ballot of his two-dozen-strong launch staff, which concluded with a string of “Go” calls throughout the board. The ultimate permission to proceed with launch got here from NRO Mission Director Col. Eric Zarybnisky.
The countdown clock resumed counting from the pre-planned maintain at T-4 minutes at 2:41 p.m. EDT. No sooner had the countdown resumed, nevertheless, than an ominous “Maintain, Maintain, Maintain” name echoed throughout the web at T-3 minutes and 58 seconds.
Clocks have been reset to T-4 minutes and holding as a flurry of to-and-fro chatter progressed between flight controllers over the countdown web. Shortly thereafter, the onset of “detanking” the Delta IV Heavy was introduced and groups entered a 24-hour recycle, aiming for a backup alternative opening at 1:37 p.m. EDT Friday.
