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A Northrop Grumman Antares rocket rolled out of its hangar on Monday night and traveled a self-propelled one-mile long journey to launch Pad 0A on Wallops Island, Virginia, for a runaway liftoff Thursday with a Cygnus supply vessel on its way to the International Space Station.
However, rainy weather and clouds at the launch base of Virginia's Eastern Shore could prevent a launch Thursday, with forecasts predicting a 70 percent probability of conditions that violate the Antares rocket launch criteria.
The two-stage Antares rocket liftoff is set at 4:49:38 AM EST (0949: 38 GMT) from Pad 0A at Mid-Atlantic Regional Spaceport, located on NASA's Wallops Flight Facility.
Weather conditions are not expected to improve much for a backup opportunity available Friday, when Wallet meteorologists predict a 65 percent chance of weather prohibiting lifting, again due to clouds and an increasing chance of wind rays.
"A low pressure area will quickly develop on Wednesday over Deep South, causing rain showers to southeastern America during the day," wrote Wallop's weather team in a forecast Tuesday morning. "These showers arrive until northeast on Wednesday evening until early Thursday, which is likely to arrive through our launch window Thursday morning. This nearer front will cause heavy clouds and a chance to rain by T-0.
"After the launch window, the rain is getting heavy sometimes with increasing winds during the day on Thursday," the forecast team wrote. "Windy conditions will continue until Friday, with winds falling on Friday night."
Conditions for a launch attempt Saturday can be greatly improved, with only 5 percent chance of weather breaking a launch weather rule.
The Antares rocket arrived on Monday evening from the horizontal integration facility on Wallops Island and traveled a multi-wheel carrier along a red southern line to start pad 0A. A mile journey occurred in steady rainfall, and ground crews steered the rocket up the ramp to launch launch at Pad 0A, where Antares launcher was elevated vertically around Tuesday night.
Final connections between the Antares rocket carrier and the launcher's power, data and fuel supply were scheduled later on Tuesday, followed by completion and testing before the countdown set-up to begin late Wednesday night.
The rocket will be launched with Northrop Grumman's Cygnus Supply Ship, named S.S. John Young to honor Apollo moonwalker and space master commander who died in January.
The technicians have finished loading equipment in Cygnus spacecraft's pressurized trays the last few days, then installed the Antares racket's nose over the spacecraft before Monday's rollout.
Cygnus spacecraft will carry approximately 7500 pounds (3,400 kilos) deliveries, experiments and hardware to the space station. The Antares rocket, powered by dual petrol-powered Russian-built RD-181 engines in the first stage and a solid-fueled US-made overhead, will deliver the load carrier to a preliminary bypass approximately nine minutes after lifting.
If it is assumed that the freighter launches Thursday or Friday, it will arrive at the rolling research complex Sunday round at. 04:35 EST (0935 GMT), when the astronauts will grab the spacecraft with the station's robot arm.
In addition to delivering food and crew regulations, payloads onboard Cygnus Spacecraft include a combination 3D printer and recycling facility built by Tethers Unlimited, a private company headquartered near Seattle. The device is designed to "make waste of plastic material into a high-quality 3D printer filament to create tools and materials, a key feature for future space visits beyond time," according to a NASA summary of the mission.
Other experiments aboard the cargo ship include a study of cement strengthening in microgravity and a study of how an astronaut's perception of motion, body position and distance to objects changes in space.
The upcoming mission will be the 11th launch of a Cygnus spacecraft transporting cargo to the International Space Station, including a test flight in 2013 and a failed Antares launch in 2014 that destroyed the supply vessel after flight.
The mission is called NG-10, and it is the first Cygnus flight since Northrop Grumman acquired Orbital ATK, which developed and flew the previous cargo missions during a 11-launch NASA contract worth almost 2.9 billion dollars.
Starting with NG-12, launched for launch by the end of 2019, Northrop Grumman will kick off a subsequent commercial resupply service contract, which guarantees the company at least six additional flights by 2024.
NASA has a similar freight transport agreement with SpaceX, and the Space Agency has assigned Sierra Nevada Corp. a resupply service agreement for logistics deliveries and returns with the Dream Chaser space plan starting in late 2020.
Cygnus spacecraft launching Thursday will be at the space station until February, as it will resign and release several CubeSats from a NanoRacks deployer before returning into the Earth's atmosphere and burning up with several tons of trash packed by station staff.
More pictures of the Antares rocket's rainy eruptions are shown below.
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