T-minus 8 hours |
Call to Stations |
The launch team reports to the control center at NASA's Wallops Flight Facility. |
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T-minus 7 hours, 30 minutes |
Complete Voice Checks |
The launch team conducts voice checks over radio loops. |
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T-minus 6 hours, 30 minutes |
Clear the Pad |
Workers evacuate the launch pad. |
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T-minus 5 hours, 35 minutes |
Poll to Initiate Fueling Sequence |
The launch team conducts a "go/no go" poll to initiate the Antares fueling sequence. |
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T-minus 5 hours |
Vehicle Power-Up |
The Antares launch vehicle is powered on using an external power source. |
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T-minus 4 hours, 5 minutes |
Poll to Initiate Pre-Launch Processing |
The launch team is polled for a "go" to begin the pre-launch processing sequence. |
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T-minus 3 hours, 40 minutes |
15-minute Hold |
The countdown holds for 15 minutes. |
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T-minus 3 hours, 30 minutes |
RF Transmitter Checks |
The launch team tests the Antares rocket's radio transmitter, which will be the communications link between the vehicle and the ground during flight. |
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T-minus 3 hours, 5 minutes |
Poll to Initiate LOX Chilldown |
The launch team is a polled for a "go" to begin the liquid oxygen chilldown, which conditions the ground and vehicle propellant lines for loading of the cryogenic propellant, which is stored at a temperature of minus 298 degrees Fahrenheit. |
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T-minus 3 hours |
Begin Liquid Oxygen Chilldown |
The liquid oxygen chilldown sequence begins. |
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T-minus 2 hours, 48 minutes |
FTS Testing |
The Antares flight termination system, which would destroy the rocket if it flew off course during launch, is tested to ensure it is ready for launch. |
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T-minus 2 hours, 24 minutes |
Enable Ordnance |
The Antares rocket's pyrotechnic charges, which are used to separate the rocket's stages and other components in flight, are set to enable. |
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T-minus 1 hour, 45 minutes |
15-minute Hold |
The countdown holds for 15 minutes. |
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T-minus 1 hour, 30 minutes |
Begin Propellant Loading |
Liquid propellants are pumped into the Antares first stage through the base of the rocket. The 12.8-foot-diameter first stage, fabricated in Ukraine, holds 21,000 gallons of RP-1 kerosene and 41,000 gallons of liquid oxygen. The Antares second stage is fueled by solid propellants, which were loaded when the stage was built. |
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T-minus 25 minutes |
Start of Engine Low-Flow Chilldown |
The chilldown sequence for the Antares rocket's two AJ26 main engines begins to prepare the engines for ignition. |
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T-minus 10 minutes |
Start of Engine Medium-Flow Chilldown |
The chilldown sequence is transitioned to a medium flow. |
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T-minus 5 minutes |
Transfer Avionics to Internal Power |
The Antares rocket's avionics are switched to run off of an internal battery. |
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T-minus 3 minutes, 30 seconds |
Initiate Terminal Countdown |
The final three-and-a-half minutes of the countdown are run off a computer autosequence. |
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T-minus 2 minutes |
Pressurize Propellant Tanks |
The Antares rocket's first stage propellant tanks are pressurized for launch. |
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T-minus 15 seconds |
Main Engine Slew Test |
The Antares rocket's AJ26 first stage engines are slewed in a preflight steering check to ensure the gimbal system is ready for flight. The engines can gimbal up to 6 degrees from center to steer the rocket. |
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T-minus 5 seconds |
TEL Retraction |
The rocket's umbilical tower, which is also used to transport and erect the vehicle at the launch pad, is retracted away from the launch vehicle. |
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T-minus 0 seconds |
Main Engine Ignition |
The two AJ26 main engines ignite with the help of a start cartridge before ramping up to a combined thrust level of approximately 750,000 pounds. |
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T+plus 1.5 seconds |
Engine Health Check Complete |
A computer-controlled health check of the performance of the AJ16 engines is completed before liftoff. |
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T+plus 2 seconds |
Liftoff |
After the engines are confirmed healthy, the hold-down system releases the Antares rocket at liftoff. |
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