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#340
by
jimvela
on 15 Jun, 2007 04:33
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About the only thing I can come up with is that they may be comparing what they're seeing on the station to a setup on the ground, and looking for differences
Almost certainly.
If you've ever watched electronic boxes pull current while they run, many will draw varying amounts of current depending on modes of operation. Especially when zoomed way in at high resolution in the time domain.
An example: things with processors in them even draw different amounts of current depending on what code is executing. That technique has been used to reverse-engineer code in embedded devices.
It gets even harder to see the picture when you're clamped around a big harness instead of individual wires as there can be multiple circuit paths, so you end up just looking for out-of-character behavior.
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#341
by
Zachstar
on 15 Jun, 2007 04:34
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"Althogh we are only seeing your hair"
Video of the process.
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#342
by
Zachstar
on 15 Jun, 2007 04:34
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#343
by
Zachstar
on 15 Jun, 2007 04:36
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Very nice view!
Soyuz & Progress docked to ISS.
Notice the solar panels of the Russian segment.
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#344
by
Ankle-bone12
on 15 Jun, 2007 04:38
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So are they going to bed or are they working extra hours?
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#345
by
reubenb
on 15 Jun, 2007 04:39
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gruff68 - 14/6/2007 11:25 PM
I'm no electrical engineer either, but what is looking at fluxuation in current draw going to prove?
The power supplies for the computers are designed to run within certain voltage and electrical noise limits and they think that one of the power sources might be out of those limits which is leading to all the computer problems they are having.
Edit: oops i think this was answered above and i didn't really answer as to why they are measuring current. i guess just because the current is proportional to the voltage?
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#346
by
Zachstar
on 15 Jun, 2007 04:44
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CPU View of the arm for the repair.
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#347
by
MKremer
on 15 Jun, 2007 04:47
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Looks pretty easy as far as SRMS operation - the operational position is just slightly above the basic unstow position.
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#348
by
Seattle Dave
on 15 Jun, 2007 04:50
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iloco - 14/6/2007 11:09 PM
I thought the "we're all denying we're electrical engineers up here". I'm no electrician, but that waveform looked weird for sure.
It's fun to assume we're all going "whoa!" at the same time as the astronauts and engineers in Houston
Sure did seem like the crew thought the same.
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#349
by
Seattle Dave
on 15 Jun, 2007 04:52
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JimO - 14/6/2007 11:25 PM
bsegal - 14/6/2007 9:31 PM
20 bucks if you can come up with a Wayne Hale pic circa that timeperiod with a full head of hair.
Bergin has my mailing address.
http://www.jamesoberg.com/image/tony_ceccacci-gary_coen-way.jpg
Gary Coen was Ascent Prop for STS-1 (this pix), later Flight Director
Tony Ceccacci was a trainee -- later Flight Director, now big ISS wheel.
I took the picture.
You are too cool Mr Oberg!
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#350
by
jimvela
on 15 Jun, 2007 04:56
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i didn't really answer as to why they are measuring current. i guess just because the current is proportional to the voltage?
Measuring current with a clamp on probe is easy- you don't have to de-mate any cables, poke any wires, insert probes, or do anything really dangerous. You just put that clamp around the cable you want to measure and watch the results.
Measuring voltage without a test point means finding some way to connect the probe leads to the voltage source. Doing that with a tech is relatively easy, doing that with pilots or engineers- that's downright scary.
If you know the electrical characteristics of the circuit you are looking at, you can calculate the voltage and or current based on the other measurement. For example one way to measure current draw in circuit is to measure the voltage drop across a precise small resistance, say .001 Ohm. Doing so with a high-impedance meter or A-to-D circuit will allow precise calculation of current by application of Ohm's law. I know of several places that this technique is used in my EGSE and in some of the flight boxes that my EGSE tests.
I assume that since they have no easy way to do something like that, the clamp on meter is what is in use. (plus, the meter is on hand- always easier to use the tool that you have instead of the one you don't) :cool:
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#351
by
NASA_Twix_JSC
on 15 Jun, 2007 05:18
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-------
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#352
by
Ankle-bone12
on 15 Jun, 2007 05:30
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sadly, I will not be home for the rest of the week because I am leaving for florida tomorrow and I will not have internet access. Hopefully I will see the shuttle land when we go out to KSC. So thank you everyone in advance for the wonderful coverage these past 7 days. Im very grateful for this site.
And sorry for getting of topic
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#353
by
NASA_Twix_JSC
on 15 Jun, 2007 05:31
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Launch Fan - 14/6/2007 10:50 PM
Or this, from Chris' new article:
'It appears the computers are sensitive to noise. Problems occurred when the truss was attached,' added another note. 'It's possible that the ground path changed with the addition of the truss, which increased the noise level. There will be some troubleshooting later today. The crew will use a scope meter to check for noise.'
Yep, that's what you've seen them use.
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#354
by
MKremer
on 15 Jun, 2007 05:44
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Ankle-bone12 - 15/6/2007 12:30 AM
sadly, I will not be home for the rest of the week because I am leaving for florida tomorrow and I will not have internet access.
Good lord, man, it's the middle of an exciting/dramatic Shuttle mission! What's wrong with you?! :laugh:
Hopefully I will see the shuttle land when we go out to KSC.
OK, well, then if you're at least planning to show up for the landing, you're excused.
:laugh:
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#355
by
Naraht
on 15 Jun, 2007 08:05
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JimO - 14/6/2007 11:25 PM
bsegal - 14/6/2007 9:31 PM
20 bucks if you can come up with a Wayne Hale pic circa that timeperiod with a full head of hair.
Bergin has my mailing address.
http://www.jamesoberg.com/image/tony_ceccacci-gary_coen-way.jpg
Gary Coen was Ascent Prop for STS-1 (this pix), later Flight Director
Tony Ceccacci was a trainee -- later Flight Director, now big ISS wheel.
I took the picture.
Great picture! Who is the fellow at the bottom left? I've seen him before, and he looks like he's about sixteen...
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#356
by
mark147
on 15 Jun, 2007 08:54
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Russian computers now totally disconnected from US power
3:24 CDT (0824 UTC) - restart attempted
All computers have power
Lane 1 central : running
Lane 2 terminal : coming in and out
Others are not working
PAO: All this not unexpected - not expecting a Eureka moment
Station now out of coverage of Russian ground sites again until the next pass
Russians aboard station talking to Russian ground controllers to give updates
Americans asleep
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#357
by
Zachstar
on 15 Jun, 2007 10:09
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Computers deactivated again.
Thanks.
ISS Director Update coming up.
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#358
by
jaredgalen
on 15 Jun, 2007 10:11
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The russian crew have also gone back to sleep....
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#359
by
Zachstar
on 15 Jun, 2007 10:26
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Current status.
Unable to communicate with the single lane properly.
Turned the US power back on.
Letting the crew get some sleep while they will make a plan.
Sure did seem like the crew thought the same.
