

SpaceX CRS-5 launch aborted, next attempt Friday - kid0m4n
https://blogs.nasa.gov/spacex/2015/01/06/actuator-issue-triggered-abort/

======
ceejayoz
[https://twitter.com/Cmdr_Hadfield/status/552432830912151552](https://twitter.com/Cmdr_Hadfield/status/552432830912151552)

> Launch scrubs reassure me. It means that the powerful desire to GO has been
> tempered by the necessity to be truly ready. Cool heads @SpaceX

~~~
pjscott
The launch abort was automated, so heads didn't need to be cool. I'm not sure
if that makes it more reassuring or less.

~~~
ceejayoz
My understanding is that while the abort was automated, it was triggered
because the engineers manually held the countdown and the launch window was
only one second. Humans set the automatic limits, anyways.

------
jccooper
For fun, here's the part probably in question:

[http://jasc-controls.com/jasc-industry-listing/space/space-a...](http://jasc-
controls.com/jasc-industry-listing/space/space-actuators/thrust-vector-
control-actuator-part-101424-5/)

A servo-controlled hydraulic linear actuator with redundant coils in the
servomotor. Probably runs using the RP-1 fuel as hydraulic fluid.

------
xgbi
I listened to the last minutes of the stream, and I was impressed at how
speedy their voices were.

I don't recall hearing such haste in Nasa's launches; it was a bit weird and
exciting at the same time.

~~~
Nogwater
It reminds me a lot of listening to air traffic control somewhere busy.

------
winslow
What is an 'actuator drift' problem? My google fu only returned stories about
this aborted launch and this article ([http://hydraulicspneumatics.com/other-
technologies/truth-abo...](http://hydraulicspneumatics.com/other-
technologies/truth-about-problem-valves)). Is my understanding correct that a
valve/piston was moving when it wasn't suppose to? What type of dangers could
this impose of the rocket/vehicle?

~~~
BrandonMarc
/r/spacex tipped me off to this 4-year-old video, which shows off what a
Thrust Vector Control test stand does, and how testing of actuators, etc is
related to sensing engine / control-surface anomalies.

[https://www.youtube.com/watch?v=Pigsq5rt-
mY](https://www.youtube.com/watch?v=Pigsq5rt-mY)

Heh, and it turns out it's a SpaceX video.

~~~
winslow
Awesome! Thanks for the video. The frequency in which it changes position is
really interesting. Didn't realize the movement involved.

------
TheCraiggers
This makes me wonder just how many sensors they have devoted entirely to
detecting problems before, during, and after lift-off.

~~~
tomschlick
My guess would be (2 x the number of critical mechanisms) 1, primary sensor
and 1 backup to make sure that one doesn't provide a false positive

