SpaceX Dragon CRS-5 ISS resupply


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anthdci

some problem with stage 2

 

 

actuator drift of some sort according to the BBC stream. I've no idea what that means.

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DocM

During the terminal count engineers observed drift on one of the two thrust vector actuators on the second stage that would likely have caused an automatic abort. Engineers called a hold in order to take a closer look. SpaceX is scrubbed for today and we are now targeting launch on Jan. 9th at 5:09am ET.

Translation: most likely during 2nd stage engine chill-down (liquid oxygen run through the turbopump to prepare for ignition) the actuators that the steer the engine are tested. A sensor reported one didn't move as expected - it's center point position drifted out of spec.

In other words; the upper stage's power steering went out, or a sensor failure made it look like it did.

Since the launch window was <1 second long they couldn't stop to check it out or replace it and try again later today, so they moved it to the backup date of Friday. Meanwhile they'll check the actuator and sensors.

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bguy_1986

Translation: most likely during 2nd stage engine chill-down (liquid oxygen run through the turbopump to prepare for ignition) the actuators that the steer the engine are tested. A sensor reported one didn't move as expected - it's center point position drifted out of spec.

In other words; the upper stage's power steering went out, or a sensor failure made it look like it did.

Since the launch window was <1 second long they couldn't stop to check it out or replace it and try again later today, so they moved it to the backup date of Friday. Meanwhile they'll check the actuator and sensors.

Are these sensors pretty flimsy or something?  Seems like they go bad all the time.

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DocM

We don't know if it was a sensor, an actuator or even a hydraulic problem yet.

As to a flimsy sensor, it happens. Same as valve or actuator issues. See Delta IV Heavy during the Orion test when they didn't know if the scrub was caused by sticking valves (a perennial problem on Delta IV) or bad sensor readings. ULA, SpaceX, Aerojet-Rocketdyne etc. get these parts from a very short list of suppliers. JASC, Johnson Conrols, Honeywell etc.

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bguy_1986

We don't know if it was a sensor, an actuator or even a hydraulic problem yet.

As to a flimsy sensor, it happens. Same as valve or actuator issues. See Delta IV Heavy during the Orion test when they didn't know if the scrub was caused by sticking valves (a perennial problem on Delta IV) or bad sensor readings. ULA, SpaceX, Aerojet-Rocketdyne etc. get these parts from a very short list of suppliers. JASC, Johnson Conrols, Honeywell etc.

Sorry, didn't mean to make it sound like everybody knew what the problem was.  Just seems like every time they are unable to launch it's due to a bad sensor or something else small.  I would think if that problem keeps happening, someone would come up with something a little better.

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DocM

Bit by bit they've been brining parts in-house, both for this and costs. They're already 3D printing liquid oxygen valves and other parts.

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PaulRocket

Do we know if SpaceX resolved the issue that caused the abort? I hope they can launch on Friday and don't need more time...

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DocM

Taking another day to make sure they squashed all the bugs,

@Spaceport_Mag

SPACEPORT MAGAZINE

@SpaceX CRS-5 will make its next launch attempt from #CCAFS on Saturday, Jan. 10 at 4:47am EST. @NASA TV coverage will begin at 3:30am.

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DocM

F9/Dragon is up on the pad. Should start propellants loading soon.

237afeb9363f91c78b3976ce693d160c.jpg

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DocM

A bit belated, but a neat pic of last nights rollout showing the grid fins,

b289126b-41ab-48d8-bd35-552b194ebe78.jpg

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DocM

KSC weather is 90% GO

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DocM

Fueling nearing completion.

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DocM

T-57 min.

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DocM

All Launch Commit Criteria: GO

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DocM

ISS synched launch time is 0447.30 EST

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DocM

NSF reports the Range Flight Termination System antenna is noisy, discussing switching to the backup.

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DocM

T-15 minutes

Polling: all GO for terminal count

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DocM

Transporter Erector retracting

T-4:00

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DocM

LAUNCH!!

Clearing the tower

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DocM

S2 separation and ignition

Textbook launch so far, S1 on the way back down.

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DocM

Stage 1 reentry burn startup

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DocM

S1 boostback burn started and ended. Now over the horizon so KSC has lost telemetry.

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DocM

KSC and Hawthorne waiting for reports from the ASDS recovery crew.

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