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CRS-3 Scrub



 
 
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  #11  
Old April 12th 14, 04:28 PM posted to sci.space.station
Greg \(Strider\) Moore
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Default CRS-3 Scrub

"David Spain" wrote in message
...

Since I am the king of old news, again in case you missed it, NROL-67 was
successfully launched on an ATLAS-5 yesterday, thus clearing the way for
Space-X CRS-3 with a still pending NET launch date of April 14.

Video of yesterday's ULA NROL-67/ATLAS-5 launch available he

http://www.youtube.com/watch?v=jt6_UUF0Xus


Dave




Well, the mission may be delayed, depending on how the space walk goes.


--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

  #12  
Old April 12th 14, 04:28 PM posted to sci.space.station
Greg \(Strider\) Moore
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Posts: 790
Default CRS-3 Scrub

"David Spain" wrote in message
...

Since I am the king of old news, again in case you missed it, NROL-67 was
successfully launched on an ATLAS-5 yesterday, thus clearing the way for
Space-X CRS-3 with a still pending NET launch date of April 14.

Video of yesterday's ULA NROL-67/ATLAS-5 launch available he

http://www.youtube.com/watch?v=jt6_UUF0Xus


Dave



Let's try that again.

The mission may be delayed depending on how the spacewalk goes:

http://www.foxnews.com/science/2014/...alk-958168569/


--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net


--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

  #13  
Old April 12th 14, 08:57 PM posted to sci.space.station
David Spain
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Default CRS-3 Scrub

On 4/12/2014 11:28 AM, Greg (Strider) Moore wrote:

The mission may be delayed depending on how the spacewalk goes:

Spacewalk? Holy holdup Batman!

What's next? Space Duck crossing?

Wait a minute. Isn't the CRS-3 bringing up the replacement EMU?
Well I believe they have two, so if they aren't walking both, we aren't
chicken and egg, yet....

Dave

  #14  
Old April 13th 14, 11:46 PM posted to sci.space.station
David Spain
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Default CRS-3 Scrub

On 4/12/2014 11:28 AM, Greg (Strider) Moore wrote:

Let's try that again.

The mission may be delayed depending on how the spacewalk goes:

http://www.foxnews.com/science/2014/...alk-958168569/


Looks like they are going to launch anyway AND do the spacewalk, (I am
getting that Kennedy earworm: "and do the other things...").

http://www.nasaspaceflight.com/2014/...m-failure-iss/


Still on for NET tomorrow (Monday) April 14 at 4:58PM EDT.

Dave

  #15  
Old April 14th 14, 06:36 PM posted to sci.space.station
Jeff Findley[_4_]
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Default CRS-3 Scrub

In article , nospam@
127.0.0.1 says...

On 4/12/2014 11:28 AM, Greg (Strider) Moore wrote:

Let's try that again.

The mission may be delayed depending on how the spacewalk goes:

http://www.foxnews.com/science/2014/...alk-958168569/


Looks like they are going to launch anyway AND do the spacewalk, (I am
getting that Kennedy earworm: "and do the other things...").


I was glad to hear this. Having backups is a good thing, but suspending
operations due to lack of certain backups must be carefully considered.
From the story below, it sounds like this has been done.

http://www.nasaspaceflight.com/2014/...m-failure-iss/


Still on for NET tomorrow (Monday) April 14 at 4:58PM EDT.


Exciting times. I'm wishing SpaceX/NASA has another successful
Dragon/ISS mission this time around.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer
  #16  
Old April 14th 14, 09:27 PM posted to sci.space.station
David Spain[_4_]
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Default CRS-3 Scrub

Scrub again! This time it's a helium leak in the first stage. We all know from the Onion video of six years back you don't mess around with those!

http://m.youtube.com/watch?v=6bQpgU67Puo

Next launch opportunity in NET Friday April 18. Weather permitting.

This thread certainly has legs.
  #17  
Old April 16th 14, 01:38 PM posted to sci.space.station
Jeff Findley[_4_]
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Posts: 411
Default CRS-3 Scrub

In article om,
says...

I understand there are a gazillion systems, switches, sensors, valves
in them fancy rockets. But...

What percentage of scrubs are due to hardware problems and not software
problems ?

Seems to me like there is enough experience with "rocket science",
liquid fuels and very cold temperatures to be able to design hardware
that would be reliable for sufficient number of system activations to
last the lifetime of the rocket ? (testing during assembly, testing at
pad, and launch).


Helium leaks are not uncommon because it's quite difficult to contain
gases with such low atomic weights. H2 is even worse. Over the life of
the space shuttle, hydrogen leaks were fairly common and proved quite
difficult to completely prevent.

Seems to me like a lot of scrubs appear releated to sensor problems.
Since rockets spend far more time at the pad than actually flying,
shouldn't reliability of those systems be increased for operation at the
pad (such as changing temperature, metal contraction when cold fuel is
loaded etc) ?

Seems to me like engineers spend a lot of time ensuring components work
during flight, but less time to ensure they work on the pad before
launch. Or is that a false impression I have ?


I think that's largely a false impression. This is why "hot fire" tests
of stages are performed. Potential problems involving leaks and/or
sensors are likely to happen during this sort of test. But problems do
sneak through and when they're found, they are dealt with. In this
case, it's better to fix the helium leak on the ground than take the
chance that it will get worse and cause problems during flight.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer
  #18  
Old April 17th 14, 12:27 PM posted to sci.space.station
Jeff Findley[_4_]
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Posts: 411
Default CRS-3 Scrub

In article om,
says...

On 14-04-16 08:38, Jeff Findley wrote:

sensors are likely to happen during this sort of test. But problems do
sneak through and when they're found, they are dealt with. In this
case, it's better to fix the helium leak on the ground than take the
chance that it will get worse and cause problems during flight.



Am not advocating that they launch despite an indication of a problem.

I just find it curious that systems built to allegedly widthstant the
rigors of launch (vibration, cold, heat etc) would often fail prior to
launch.

You would think that a helium valve would be tested fairly extensively
under simulated pad conditions when it is developped and that each item
would also get tested prior to being installed in a rocket. So why would
it then fail when on the rocket on pad at very last minute ?

Or is this really an issue of components not getting sufficient testing
to debug them while being developped ?


Hard to say since SpaceX is private. But, they were forced to develop
their own hardware when they couldn't source such aerospace hardware in
the US for reasonable prices. Because of this, they faced the same
learning curve others had already conquered. As such, there have been
issues with these sorts of things, like Dragon flight which had the
issue with the Dragon propulsion system failing to pressurize correctly.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer
  #19  
Old April 18th 14, 05:38 PM posted to sci.space.station
David Spain[_4_]
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Posts: 314
Default CRS-3 Scrub

On Thursday, April 17, 2014 7:27:45 AM UTC-4, Jeff Findley wrote:
Hard to say since SpaceX is private. But, they were forced to develop

their own hardware when they couldn't source such aerospace hardware in

the US for reasonable prices. Because of this, they faced the same

learning curve others had already conquered. As such, there have been

issues with these sorts of things, like Dragon flight which had the

issue with the Dragon propulsion system failing to pressurize correctly.



Jeff


They were lucky that in doing so they did run afoul of ITAR.

Still on today for a 3:25PM EDT launch time.

Dave


Dave
  #20  
Old April 18th 14, 05:41 PM posted to sci.space.station
David Spain[_4_]
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Posts: 314
Default CRS-3 Scrub

On Thursday, April 17, 2014 7:27:45 AM UTC-4, Jeff Findley wrote:
Hard to say since SpaceX is private. But, they were forced to develop
their own hardware when they couldn't source such aerospace hardware in
the US for reasonable prices. Because of this, they faced the same
learning curve others had already conquered. As such, there have been
issues with these sorts of things, like Dragon flight which had the
issue with the Dragon propulsion system failing to pressurize correctly.

Jeff


In doing so, if they had to spec. specific parts from a foreign manufacturer they are lucky they didn't get hit with ITAR.

Still on time for a launch today at 3:25PM EDT. Looks like low overcast at the Cape today, so probably not visible for long.

Dave
 




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