United Launch Alliance’s penultimate Delta IV Heavy rocket will take flight on the NROL-68 mission Wednesday, lofting a secretive payload for the National Reconnaissance Office. Liftoff, from Space Launch Complex 37B at Cape Canaveral, is predicted at 3:29 AM EDT (07:29 UTC).
Wednesday’s mission, designated NRO Launch 68 (NROL-68) is being flown on behalf of the National Reconnaissance Office (NRO), the agency accountable for operating america’ fleet of reconnaissance and intelligence-gathering satellites. Like a lot of the agency’s spacecraft, the true nature and purpose of the NROL-68 mission stays classified, nevertheless, clues from previous missions and knowledge that has over time leaked into the general public domain do paint an image of what a lot of the NRO’s satellites are used for.
Within the case of NROL-68, the 2 most important pointers are using a Delta IV Heavy rocket, and the alternative of launch site. Recent SpaceX polar corridor missions aside, Cape Canaveral Space Force Station is primarily used for launches targeting low and mid-inclination orbits, with rockets flying in an easterly direction over the Atlantic Ocean. In contrast, Vandenberg Space Force Base in California handles the vast majority of high-inclination launches. Navigational areas posted for Wednesday’s launch corroborate that this can be a low-inclination mission with the hazard areas for the mission indicating that the rocket will fly due east after liftoff.
This means that the launch is targeting a geosynchronous or geostationary orbit, while using a Delta IV Heavy — one of the crucial powerful rockets on the NRO’s disposal — indicates that a major amount of performance can be required to finish the mission. This means a fairly heavy payload for the goal orbit.
Wednesday’s launch marks the fifteenth flight of a Delta IV Heavy, and its eleventh mission in support of the NRO. Its ten previous NRO missions have been a good split between high-inclination low-Earth orbit launches from Vandenberg and geostationary launches from Cape Canaveral. The entire geostationary launches are believed to have carried the identical sort of payload: an electronic signals intelligence (ELINT) satellite which is often called Orion. It’s due to this fact reasonable to assume that Wednesday’s launch can be carrying one other Orion satellite.
One other indication that NROL-68’s payload is an Orion satellite is the payload fairing that’s getting used on Wednesday’s launch. This can be a trisector fairing manufactured from aluminium, derived from the Titan IV’s payload fairing, quite than the more modern composite material bisector fairing that was developed for the Delta IV program. A trisector fairing differs from a more common bisector one in that it separates into three sections as an alternative of two. The Orion satellites, which were launched aboard Titan IV prior to its retirement, appear to require this fairing as the entire previous geostationary NRO missions on Delta IV have used it — as did one early non-NRO mission which was also carrying a legacy Titan payload.
The Orion satellites themselves were introduced to interchange a series of 4 smaller satellites named Rhyolite and later Aquacade, which were launched on Atlas-Agena rockets between 1970 and 1978. Orion itself appears to have passed through a minimum of two generations of satellites, with the primary two satellites being deployed from Space Shuttle with assistance from an inertial upper stage during its STS-51C and STS-33 missions in 1985 and 1989 respectively. After national security missions transitioned back to expendable launch vehicles, two more satellites were launched in 1995 and 1998 using Titan IV rockets with Centaur upper stages.
Leaked documents published by the news website The Intercept in 2017 showed that these first 4 satellites were designated Mission 7605 to 7608, while later satellites began a brand new series starting with 8301. These documents also indicated that the 8300-series satellites included communications intelligence capabilities allowing them to take over this role from a previous series of dedicated satellites which had been known by several codenames including Chalet, Vortex and Mercury.
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The NROL-68 mission patch. (Credit: NRO)
The primary of those new-generation satellites was launched in September 2003, marking the ultimate Orion mission aboard a Titan IV rocket before missions switched to the Delta IV. Subsequent launches followed in January 2009, November 2010, June 2012, June 2016, and most recently December 2020 with the NROL-44 mission. The Delta IV Heavy’s final flight is scheduled to occur from Cape Canaveral next 12 months with the NROL-70 mission, which can almost certainly carry one other Orion.
The mission patch for the NROL-68 mission prominently incorporates a dragon — an emblem that has appeared on patches for numerous previous NRO signals intelligence missions, and particularly previous Orion launches.
Delta IV is one in every of two rockets developed under what was then the US Air Force’s Evolved Expendable Launch Vehicle (EELV) program, which began within the Nineteen Nineties to interchange the fleet of rockets then servicing the US military’s launch needs with a pair of standardized designs. Each successful rockets, Boeing’s Delta IV and Lockheed Martin’s Atlas V, first flew in 2002 and were offered in quite a lot of configurations to fulfill the differing requirements of varied missions. Originally these included small, medium, and heavy versions of the rockets, although neither rocket would ever fly in its “small” configuration, and the Atlas V Heavy configuration would also never make it to the launch pad — leaving the biggest and heaviest national security payloads solely to Delta IV Heavy until the appearance of SpaceX’s Falcon Heavy.
United Launch Alliance (ULA) was formed in December 2006, merging Boeing and Lockheed Martin’s Delta and Atlas programs under a single operator as a part of the settlement of a lawsuit between the 2 firms. Boeing had previously been found to have illegally acquired documents from Lockheed Martin related to the Atlas V rocket and Lockheed Martin’s EELV bid.
The EELV program has since been renamed National Security Space Launch (NSSL) and is now operated by the US Space Force. NSSL Phase 2 contracts were awarded in August 2020 to SpaceX for its Falcon rockets and ULA for its next-generation Vulcan launch vehicle, to interchange Atlas V and Delta IV. Two other proposals were rejected: Northrop Grumman has since abandoned work on its OmegA rocket, while Blue Origin is continuous to develop its Recent Glenn vehicle outside of this system.
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Delta IV Heavy launches with NROL-44 in 2020, its most up-to-date East Cost mission. (Credit: Stephen Marr for NSF/L2)
With Falcon 9 and Falcon Heavy already in service and Vulcan scheduled to make its maiden flight later this 12 months, Atlas V and Delta IV are each winding down operations. The last medium-class Delta IV launch was made in 2019 using the Medium+(4,2) configuration, with remaining launches on this weight class using Atlas V or Falcon 9. Delta IV Heavy has been kept in service attributable to its unique capabilities and is flying out its manifest of specialist national security missions. Essentially the most recent Delta IV Heavy launch prior to Wednesday took place last September with NROL-91, and marked the rocket’s final mission from Vandenberg Space Force Base on the West Coast.
Delta IV launches from the East Coast happen from Space Launch Complex 37B (SLC-37B) on the Cape Canaveral Space Force Station. This launch pad was originally constructed for the Apollo program within the Nineteen Sixties, but was completely rebuilt for Delta IV ahead of its maiden flight in 2002. Rockets undergo assembly within the horizontal integration facility near the launch pad before being erected in position. A mobile service tower (MST) encloses the rocket while it’s on the launch pad and supports the installation of the payload — already encapsulated in its fairing — after the rocket has already been raised to its vertical orientation and accomplished its wet dress rehearsal.
Delta rockets have been given flight numbers, or Delta numbers, dating back to the primary flight of the Thor-Delta rocket in May 1960. Although Delta IV is a really different rocket from previous members of the Delta family, it has continued this tradition, and Wednesday’s mission is numbered Delta 388 (D388).
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Delta IV Heavy is rolled to the launch pad ahead of the NROL-68 mission. (Credit: United Launch Alliance)
Delta IV Heavy is a two-stage rocket that burns only cryogenic propellant: liquid hydrogen oxidized by liquid oxygen. Its first stage consists of three common booster cores (CBCs) burning in parallel, with a five-meter-diameter Delta cryogenic second stage (DCSS) stacked on top. Each CBC is powered by a single Aerojet Rocketdyne RS-68A engine, while the DCSS has an RL10C-2-1 powerplant.
The ultimate countdown to launch will begin on Tuesday, with the MST being moved away from the rocket and propellant loading commencing on the CBCs and DCSS. As a consequence of the extremely cold temperatures, propellant will continually boil off because the countdown progresses so the tanks will proceed to be topped off until the tanks are pressurized a couple of minutes before liftoff.
The ignition sequence for Delta IV Heavy begins at concerning the T-7 second mark within the count when the RS-68A engine on the starboard CBC is lit. The port and center cores will ignite about two seconds later, with the staggered startup serving to burn off hydrogen across the base of the rocket, reducing the fireball that has been seen on this area during previous launches. It just isn’t unusual to see a Delta IV Heavy lift off with insulation on the aft end of the rocket on fire, nevertheless, this doesn’t pose a major risk to the mission and can quickly burn out because the vehicle ascends.
Liftoff itself is predicted at T0, with the rocket starting a pitch-and-yaw maneuver after clearing the tower, about 9.4 seconds into the mission, to place it on an easterly track toward geostationary orbit. Shortly afterwards the core CBC’s engine can be throttled right down to its partial thrust mode. Delta 388 will reach Mach 1, the speed of sound, about 78.5 seconds after liftoff. Two seconds later it can go through Max-Q, or maximum dynamic pressure, the purpose within the flight at which it’s exposed to the best stress by aerodynamic forces.
About three minutes and 56.3 seconds after liftoff, the 2 outboard CBCs will shut down. The boosters will separate 1.8 seconds after cutoff, with the middle core throttling back as much as its high power level as first stage flight continues. Burnout of the middle CBC, designated booster engine cutoff (BECO), is predicted on the five-minute, 36-second mark within the mission. Six and a half seconds after BECO, the primary and second stages will separate, with the DCSS taking on for the rest of Wednesday’s mission.
The DCSS will ignite its RL10C-2-1 engine seven seconds after staging, having first deployed its extendable nozzle. NROL-68 is the second launch to feature the RL10C-2-1, which was introduced on last 12 months’s NROL-91 mission to interchange the RL10B-2 used on previous Delta IV missions. The RL10C increases standardization across the RL10 family of engines, with the RL10C-1 having replaced the RL10A-4-2 on Atlas V launches with single-engine upper stages.
Payload fairing separation is scheduled for six minutes, 37.5 seconds mission elapsed time. On NRO launches, fairing separation is the purpose within the flight at which official coverage and updates on the launch conclude, and the mission enters a media blackout. Since Orion satellites should be inserted directly into geostationary orbit, the mission will proceed for several hours during which period the DCSS will perform three burns.
Based on timings from the primary Delta IV Heavy launch, which carried an illustration satellite and aimed to simulate a national security launch to geostationary orbit, the primary burn will be expected to last about seven minutes to establish an initial parking orbit. After a brief coast, the DCSS will restart its engine for about eight minutes to succeed in geostationary transfer orbit. After an prolonged coast of around five hours — allowing it to succeed in the apogee, or the very best point, of its orbit — the DCSS will fire its engine for a 3rd and final time. This burn, of around three and 1 / 4 minutes, will circularise the orbit at geostationary altitude and reduce its inclination to zero degrees.
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Delta 388’s second stage during integration operations. (Credit: United Launch Alliance)
For the reason that Delta IV has evolved since its maiden flight, it is probably going that the timings of those burns could also be barely different during Wednesday’s mission, nevertheless, details are unlikely to be made public. Spacecraft separation can occur a couple of minutes after the top of the ultimate burn, with DCSS then performing a collision avoidance maneuver to take itself out of geostationary orbit, reducing the chance of it colliding with other satellites.
Following Wednesday’s mission, ULA has just one Delta IV launch remaining: NROL-70 is currently scheduled to lift off from the identical launch pad at Cape Canaveral next February. Before then, ULA plans to launch the debut flight of its Vulcan rocket with the industrial Peregrine lunar lander aboard. The corporate also has several Atlas V missions planned later this 12 months, including the primary crewed mission for Boeing’s Starliner spacecraft.