ICESat-II, ELaNa-XVIII: ELFIN, IT-SPINS, CHEFsat - Delta II 7420-10C - Vandenberg SLC-2W -15.09.2018

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4:19 a.m. PDT (1119 UTC)

Confirmation has been received that the rocket's guidance and control system has been powered and brought online.

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4:21 a.m. PDT (1121 UTC) -- LOX loading begins

This is Delta Launch Control at T-minus 1 hour, 10 minutes (L-1 hour, 25 minutes) and counting. Flow valves have opened and liquid oxygen is streaming into the base of the Delta II rocket at Vandenberg Air Force Base's Space Launch Complex-2.

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4:25 a.m. PDT (1125 UTC) – Launch window update

With LOX load now underway, today's usable launch window has narrowed from two hours, 34 minutes to a total duration of 69 minutes, extending from 5:46 to 6:55 a.m. PDT (8:46-9:55 a.m. EDT; 1246-1355 UTC).

This narrowing ensures that the kerosene fuel on the first stage remains at an optimal temperature and does not become too cold from the cryogenic liquid oxygen during a prolonged launch window.

The kerosene and LOX are consumed by the Aerojet Rocketdyne RS-27A main eying during the initial four-and-a-half minutes of flight to propel the vehicle to the edge of space before staging.

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09/15/2018 14:46 Stephen Clark

One hour until launch. No problems are being discussed by the ULA launch team at this time. Here are some statistics on today's launch:

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• 381st Delta rocket launch since 1960
• 237th Delta launch with NASA involvement
• 155th Delta 2 rocket mission since 1989
• 14th Delta 2 to fly in the 7420 configuration
• 241st flight of an RS-27 engine
• 277th flight of an AJ10 engine
• 54th Delta 2 mission overseen by NASA
• 45th Delta 2 rocket launch from Vandenberg Air Force Base
• 3rd launch of the Delta family in 2018
• 7th United Launch Alliance flight this year
• 130th ULA launch overall
• 7th launch from Vandenberg Air Force Base in 2018
  

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4:48 a.m. PDT (1148 UTC)

Liquid oxygen loading has been accomplished for today's countdown, completing in 26 minutes and 38 seconds. The rocket's tank will be replenished through the remainder of the count to replace the super-cold LOX that warms and naturally boils away.

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09/15/2018 14:58 Stephen Clark

The liquid oxygen tank on the Delta 2 rocket's first stage is now full. Liquid oxygen will continue flowing into the tank throughout the countdown to replace the super-cold oxidizer as it boils away. The liquid oxygen loading operation in today's countdown took 26 minutes, 38 seconds.

With the completion of liquid oxygen tanking, the Delta 2 rocket now stands fully fueled for launch with the ICESat 2 satellite at 5:46 a.m. PDT (8:46 a.m. EDT; 1246 GMT) from Vandenberg Air Force Base, California. RP-1 fuel was loaded into the first stage earlier in the countdown, and the second stage received its blend of Aerozine 50 and nitrogen tetroxide hypergolic propellants earlier in the launch campaign. The four solid rocket boosters came with their propellants pre-packed.

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NASA_LSP‏Подлинная учетная запись @NASA_LSP 4 мин. назад

The Electron Losses and Fields Investigation (ELFIN), the Damping and Vibrations Experiment (DAVE), and SurfSat will be doing a variety of space weather and microgravity experiments in orbit.

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ULA‏Подлинная учетная запись @ulalaunch 7 мин. назад

We have just entered the final planned hold - a 5-minute hold - in the countdown. #DeltaII #ICESat2 http://bit.ly/dii_icesat2 

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ULA‏Подлинная учетная запись @ulalaunch 11 мин. назад

New launch time for #DeltaII #ICESat2: 6:02 a.m. PDT. The shift gives the team additional time to resolve a temperature issue on the second stage.