As you may have noticed, there are three mechanical arms reaching from the fixed umbilical tower to the Delta IV Heavy rocket and Orion spacecraft at the pad. The arms hold a series of lines and cables that are connected to the rocket during the countdown.
For Orion, the lines provide power and atmosphere control for the spacecraft inside the fairing. The arms connecting to the rocket hold lines that perform a number of functions including carrying gaseous hydrogen fuel away from the rocket. These devices would obviously be close to the rocket as it lifts off, so at the last moments of the countdown, they will revolve away from the Orion and Delta IV Heavy as they begin their climb toward space. That movement is what gives the mechanisms their name: swing arms.
Photo credit: NASA/Bill Ingalls
Good morning everyone and hello again from Cape Canaveral Air Force Station in Florida where we have set the stage anew for a liftoff of the Orion spacecraft on its first flight test!
Our launch window opens at 7:05 a.m. EST and that is the time the launch team is aiming for today. The liftoff can take place anytime up to 9:44 a.m. if the launch team needs the time to wait for acceptable weather or take care of any technical issues.
The weather conditions deteriorated somewhat since yesterday and forecasters have trained their sights on a rain system coming up from the south. The official forecast calls for a 40 percent chance of acceptable conditions today.
Controllers also continue to monitor the fill-and-drain valves on the Delta IV Heavy following problems that developed late in the countdown Thursday. The team evaluated the valve conditions throughout the past 24 hours and came up with alternate techniques for the devices that seal the fuel tanks in the moments before liftoff.
So there is a lot going on here but the excitement of the first flight test of a new spacecraft designed for humans remains very high. Orion, designed for missions beyond low Earth orbit carrying astronauts, is secure atop the Delta IV Heavy and all of its systems are in good shape this morning. Over in the Pacific Ocean, just off the Baja California coast, the recovery forces are standing by to pull Orion from the ocean at the end of its 4.5-hour flight test.
All the propellant tanks on the Delta IV Heavy’s core boosters and second stage are fully loaded for launch. Pumps are topping off the oxygen and hydrogen tanks and the countdown is proceeding toward a 7:05 a.m. EST liftoff, the opening of a 2-hour, 39-minute window that extends to 9:44 a.m. EST.
The weather conditions have cleared and are now acceptable, reports Weather Officer Kathy Winters. The forecast has not changed, with chance of acceptable conditions remaining at 40 percent for launch time this morning.
Also, the launch team completed fueling the three core boosters of the Delta IV Heavy and pumps are now in trickle mode meaning they will top off the tanks as the countdown moves ahead and a small amount of the cryogenic propellants boil off.
Current weather conditions at Cape Canaveral are observed red because of cumulus clouds and precipitation over the launch site. The good news is that both of those violations are expected to clear in about an hour, said Kathy Winters, weather officer for the Air Force’s 45th Weather Squadron.
Liquid oxygen is being pumped into the Delta IV Heavy’s three core boosters. The RS-68A engines, one at the base of each booster core, burn liquid hydrogen and oxygen to produce the thrust needed to lift Orion off the launch pad and start it on its way to orbit. The second stage, which is also beginning to be filled with propellant, uses the same combination of hydrogen and oxygen though not nearly as much as the first stages use.
Pumps have begun the slow-fill stage of loading liquid hydrogen into the core boosters of the Delta IV Heavy this morning. Each of the three core stages holds some 110,000 gallons of the propellant which is kept chilled to minus 423 degrees F. Liquid oxygen at minus 297 degrees will begin loading soon.
Air Force meteorologists lowered their expectations for acceptable conditions during today’s launch window for the launch of the Orion Flight Test. The concerns center on a rain system moving up from the south this morning. The system could bring rain and or higher winds that would not allow a liftoff today.
Forecasters will watch conditions around the Cape Canaveral launch site throughout the countdown giving regular reports to the launch team.
Meanwhile, the launch team is beginning the process for fueling the Delta IV Heavy rocket so it will be ready for launch during the 2-hour, 39-minute launch window that opens at 7:05 a.m. EST.
The Orion/Delta IV launch teams approved fueling this morning of the Delta IV Heavy rocket with cryogenic propellants. Controllers have begun the first steps in prepping the rocket’s fuel and oxygen tanks before pumping the super-cold liquid oxygen and liquid hydrogen into the core boosters and second stage.
The weather forecast for today calls for a 40 percent chance of acceptable conditions during the launch window which opens at 7:05 a.m. EST and closes at 9:44 a.m.