Ready for the blast shortly after sunset Wednesday with payload classified for the US government’s spy satellite agency, a United Launch Alliance Atlas 5 rocket was delivered to its launch pad at Cape Canaveral on Tuesday afternoon after an unplanned trip back inside its integrated building for repairs.
The 206-foot (63-meter) Atlas 5 rocket reached platform 41 at Cape Canaveral Air Station at around 5:30 pm EST (2230 GMT) Tuesday after a 1,800-foot cruise from ULA’s Vertical Integrated Facility. Driven by locomotives, the Atlas 5 and its mobile launchers followed the track leading to the launch pad at launch 41.
The deployment follows the same path the missile traveled on Monday, when the ULA moved Atlas 5 to the launch pad before scheduled to take off on Tuesday night. But officials have asked Atlas 5 to return inside the VIF to address concerns with an air-conditioned air-conditioning system line for the National Reconnaissance Office’s payload overhead. fire.
After bringing the rocket back to VIF on Monday night, technicians swapped the pipes of the problematic environmental control system, which could have been damaged by high winds during Atlas 5’s first voyage. to the pedestal. Tory Bruno, president and CEO of ULA, tweeted that the company has installed a reinforcing pipe in its place.
The handover of Atlas 5 to VIF allows workers to use the platforms to access the site of the chain of environmental control systems, which ULA says is inaccessible at the launch pad.
After the repair work was completed, the ground personnel recovered the work platform and rolled Atlas 5 back to base 41. Once on the platform, the teams planned to connect the Atlas 5 to the ground system. at base 41 and the ground team of ULA will complete the inspection. and other activities.
Liquid oxygen will be charged to the first stage during the Wednesday afternoon countdown, along with liquid hydrogen and liquid hydrogen for the upper phase of Atlas 5’s Centaur. RP-1 fuel for the first phase was refilled last month during a countdown costume maneuver.
The latest forecast released this morning shows a 70% chance of favorable weather conditions for launch at 5:54 p.m. EST (2258 GMT). The main concern about the weather is the earthy winds at Cape Canaveral.
Predictors predict the surface winds in an east-northeast direction between 20 and 26 knots at the time of launch, with clouds bursting at 3,000 feet. The temperature at the launch had to be around 75 degrees Fahrenheit.
Expected take-off time is about 19 minutes after sunset. Assuming clear skies, Atlas 5 and its exhaust trail could produce a breathtaking display in the twilight sky over Florida’s Space Coast.
Wednesday’s launch – designated NROL-101 – will mark the 86th flight of the Atlas 5 missile since 2002, and Atlas 5’s fifth mission this year. This will be ULA’s 30th mission for the NRO, which owns a fleet of reconnaissance satellites that provide optical and radar imagery, intercepted signals and communications from enemies, and other data. for US government intelligence agencies.
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The NRO has not disclosed the payload on the NROL-101 mission yet, but warnings issued to the pilots and marines suggest that the Atlas 5 missile will head northeast from Cape Canaveral. , following a parallel route to the former US East Coast flying near Canadian maritime provinces.
Orbits indicate that Atlas 5 will release the NRO payload into a high-inclined orbit.
The NRO owns satellite relay data and a number of spacecraft designed to intercept communication signals in elliptical Molniya-type orbit spanning nearly 25,000 miles (40,000 km) above Earth at their highest point. . Those orbits are tilted about 63 degrees above the equator, allowing the satellite to regularly observe Russia and other parts of the Northern Hemisphere.
According to many independent experts specializing in tracking spy satellite activity, the Atlas 5, scheduled to launch Wednesday, could be in a similar Molniya-type orbit.
The NROL-101 mission launch vehicle will fly in the Atlas 5 “531” configuration with three solid boosters and a 5.4 meter (17.7 feet) diameter pipeline.
The NROL-101 mission payload shield will fly in medium length variant, delivering greater mass to a graded spacecraft compared to a standard shroud of 5.4 meters diameter. shorter. The average length 5.4 meter fairing has flown in the previous seven Atlas 5 missions.
Wednesday’s launch will be the fourth time an Atlas 5 missile flies in the 531 variant, but it will be the first to be launched with the new GEM 63 strap boosters produced by Northrop Grumman. They look, fit, and function like the AJ-60A solid boosters built by Aerojet Rocketdyne that flew on all previous Atlas 5 missions that required a powered engine.
GEM 63 engines are 66 feet (20 meters) long and 63 inches (1.6 meters) wide. They can generate 373,800 pounds of thrust at maximum capacity.
ULA says the GEM 63 engine is less expensive and easier to use during its launch. According to the ULA, the company’s next-generation Vulcan Centaur missile will fly with a larger Northrop Grumman solid-fuel tank called the GEM 63XL, and the introduction of a new rocket engine on the Atlas 5 would help eliminate the previous risk. the first Vulcan Centaur launch, according to the ULA.
The three GEM 63 boosters on the NROL-101 mission will ignite on the launch pad and burn in 94 seconds, consuming 97,500 pounds (44.2 tons) of pre-packed solid launchers before takeoff at T + plus 1 53 seconds, to fall into the sea.
Atlas 5’s RD-180 primary engine will continue to fire, after which the missile consumes its payload at T + plus 3 minutes and 19 seconds, after soaring over dense layers. the more, the lower of the atmosphere.
The United Launch Alliance will conclude live broadcasts of the launch after splitting the payload splitter, and the rest of the mission will take place while government-ordered news awaits. The NRO typically requires its launch contractors to end live coverage within the first few minutes of a flight.
Assuming the remainder of the mission follows the standard Atlas 5 launch profile, the RD-180 will stop working for about 4 and a half minutes after flight, followed by a few seconds of initial phase split and ignition on the Centaur on the RL10 engine of the stage.
The RL10 engine can fire once or more during flight Wednesday night, depending on the last trajectory targeted to deploy the top-secret NRO payload.
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