🚀 go-pugleaf

On Mon, 06 Aug 2012 16:15:32 +1000, Don McKenzie <5V@2.5A>
wrote:

>Been there, done that :-)
>
>http://www.abc.net.au/news/2012-08-06/nasa-celebrates-successful-mars-landing/4180454

I started watching the NASA channel about 4 hours ago and
stayed with it. (Still watching, while they are doing the
news conference event and just finished congradulating each
member of the EDL team (entry, descent, and landing.)

Australia was part of this success, as well -- at least in
terms of participating in the very much needed communications
portions.

What impresses me the most is that this trip was about 350
million miles, ending in a tight coordination with two
orbiting satellites, the ODY and MRO, and deploying novel
technologies to land a 1 ton vehicle (if I heard correct.)
Hard to believe that all of this could come together as well
as it did.

Jon

On 6/08/2012 4:15 PM, Don McKenzie wrote:
>
> Been there, done that :-)
>
> http://www.abc.net.au/news/2012-08-06/nasa-celebrates-successful-mars-landing/4180454
>
>
>
I did wonder whether the cheers were perhaps just a few seconds 
premature. The skycrane has to clear the area lest it crash onto 
Curiosity, or debris thrown up by the crash damages it.

Sylvia.

"Jon Kirwan"

>
> What impresses me the most is that this trip was about 350
> million miles, ending in a tight coordination with two
> orbiting satellites, the ODY and MRO, and deploying novel
> technologies to land a 1 ton vehicle (if I heard correct.)
> Hard to believe that all of this could come together as well
> as it did.



** Wonder if  "  Howard Wolowitz "  will be offering any chubby babes the 
chance to drive this little BUGGY  on Mars  ??




....  Phil 

On Aug 6, 9:43 am, Jon Kirwan <j...@infinitefactors.org> wrote:
> ...
> What impresses me the most is that this trip was about 350
> million miles, ending in a tight coordination with two
> orbiting satellites, the ODY and MRO, and deploying novel
> technologies to land a 1 ton vehicle (if I heard correct.)
> Hard to believe that all of this could come together as well
> as it did.
>
> Jon

Same feelings here - very well done. I just cannot imagine
how tense it must have been for the people (person?) whose
baby this is; I know I have had my tense moments shipping
overseas the first spectrometers and waiting for them to
call home and work with HPGe detectors (each being generally
a unique personality) they have never seen; I also know the
relief at the end of it.
And the scales are simply not comparable; how do these
people survive the wait is just beyond me, I guess.

Dimiter

------------------------------------------------------
Dimiter Popoff               Transgalactic Instruments

http://www.tgi-sci.com
------------------------------------------------------
http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/

> http://www.abc.net.au/news/2012-08-06/nasa-celebrates-successful-mars-landing/4180454
>

Great achievement, but have we forgotten something?
I was surprised when I mentioned to some friends that there have been 
successful landings on Mars since at least 1976 - they were astonished 
and disbelieving.

On 07-Aug-12 8:13 AM, Jordan wrote:
>
>
>> http://www.abc.net.au/news/2012-08-06/nasa-celebrates-successful-mars-landing/4180454
>>
>
> Great achievement, but have we forgotten something?
> I was surprised when I mentioned to some friends that there have been successful landings on Mars since at least 1976 -
> they were astonished and disbelieving.

Try and get people to believe that the Concord and 747 first flew in 1969, or that the B52 proto took to the air in 1952.

BTW The B52 is still a current work horse.
Only 6 new heads and 3 new handles. :-)


-- 
Don McKenzie

Web's best price on Olinuxino Linux PC:
http://www.dontronics-shop.com/olinuxino.html

The World's Cheapest Computer:
DuinoMite the PIC32 $23 Basic Computer-MicroController
http://www.dontronics-shop.com/the-maximite-computer.html
Add VGA Monitor/TV, and PS2 Keyboard, or use USB Terminal
Arduino Shield, Programmed in Basic, or C.

On 2012-08-06, Don McKenzie <5V@2.5A> wrote:

> Been there, done that :-)
>
> http://www.abc.net.au/news/2012-08-06/nasa-celebrates-successful-mars-landing/4180454

I thought the over-hyped commentary during the landing and especially
in pre-landing videos (like the "Seven Minutes of Terror") was
embarassing and made the design engineers and mission planners sound
incompetent.

The commentators kept yammering on about how there was "zero margin
for error", and how "absolutely everything has to work right".

Really?  A design with _zero_ safety margin?  Who signs off on a
system design or mission plan like that? 

I'm pretty sure that the "absolutely everything has to work right" is
also bullshit.  I heard several people who seemd know know which way
was up talking about redundancy in the hardware design, the software
design, and in the mission planning itself.

The blockbuster-movie-preview-preview-style-over-hyped-bullshit just
detracted from what in reality was an utterly brilliant job.  Even
though nothing _did_ go wrong (AFAICT), and they hit center of the
bullseye, I'm confident that there was both redundancy and margin for
error designed/built into almost everything.

-- 
Grant Edwards               grant.b.edwards        Yow! Hey, wait
                                  at               a minute!!  I want a
                              gmail.com            divorce!! ... you're not
                                                   Clint Eastwood!!

"Jordan"
>
> Great achievement, but have we forgotten something?
> I was surprised when I mentioned to some friends that there have been 
> successful landings on Mars since at least 1976 - they were astonished and 
> disbelieving.


** The first successful landing of a Mars probe complete with small "rover " 
vehicle was in December 1971.

http://en.wikipedia.org/wiki/Mars_3

The Soviets reached the moon with a probe in September 1959.

http://en.wikipedia.org/wiki/Luna_2



...   Phil 

On 7/08/2012 8:56 AM, Grant Edwards wrote:
> On 2012-08-06, Don McKenzie <5V@2.5A> wrote:
>
>> Been there, done that :-)
>>
>> http://www.abc.net.au/news/2012-08-06/nasa-celebrates-successful-mars-landing/4180454
>
> I thought the over-hyped commentary during the landing and especially
> in pre-landing videos (like the "Seven Minutes of Terror") was
> embarassing and made the design engineers and mission planners sound
> incompetent.
>
> The commentators kept yammering on about how there was "zero margin
> for error", and how "absolutely everything has to work right".
>
> Really?  A design with _zero_ safety margin?  Who signs off on a
> system design or mission plan like that?
>
> I'm pretty sure that the "absolutely everything has to work right" is
> also bullshit.  I heard several people who seemd know know which way
> was up talking about redundancy in the hardware design, the software
> design, and in the mission planning itself.

Even the animated video of the skycrane clearly shows the rockets in 
pairs, with only one of each pair in use.

Sylvia.

Jon Kirwan wrote:

> On Mon, 06 Aug 2012 16:15:32 +1000, Don McKenzie <5V@2.5A>
> wrote:
>
> >Been there, done that :-)
> >
> >http://www.abc.net.au/news/2012-08-06/nasa-celebrates-successful-mars-landing/4180454
>
> I started watching the NASA channel about 4 hours ago and
> stayed with it. (Still watching, while they are doing the
> news conference event and just finished congradulating each
> member of the EDL team (entry, descent, and landing.)
>
> Australia was part of this success, as well -- at least in
> terms of participating in the very much needed communications
> portions.
>
> What impresses me the most is that this trip was about 350
> million miles, ending in a tight coordination with two
> orbiting satellites, the ODY and MRO, and deploying novel
> technologies to land a 1 ton vehicle (if I heard correct.)
> Hard to believe that all of this could come together as well
> as it did.

I like many watch the landing  coverage. There are two
things that really impressed me.

1) The navigation to get them there on a really small landing
    footprint

2) With all of the technology in the systems to land this
successfully, one number still is impressive. There were still
250 single point possible failures. The math against it working
was astronomical. If there was anyone involved reading
this I am all ears and you have my congratulations.

Listing to the systems readout after the landing showed it
almost everything was nominal.

Congratulations all

Walter Banks

On Mon, 6 Aug 2012 12:50:50 -0700 (PDT), dp <dp@tgi-sci.com>
wrote:

>On Aug 6, 9:43�am, Jon Kirwan <j...@infinitefactors.org> wrote:
>> ...
>> What impresses me the most is that this trip was about 350
>> million miles, ending in a tight coordination with two
>> orbiting satellites, the ODY and MRO, and deploying novel
>> technologies to land a 1 ton vehicle (if I heard correct.)
>> Hard to believe that all of this could come together as well
>> as it did.
>>
>> Jon
>
>Same feelings here - very well done. I just cannot imagine
>how tense it must have been for the people (person?) whose
>baby this is;

Dr. Adam Steltzner probably deserves very high praise. And I
very much appreciated his sincere comments about others on
his team (some, he said, were better deserving and more
skilled than he) to have been given the honor he was given in
leading the EDL team who worked so hard at perhaps the more
problematic parts of the problem starting 7-8 years ago. I'm
sure he slave-drove these people, but he also was provided
the source of confidence and the energy to push through
problems with consistent and overwhelming force.

>I know I have had my tense moments shipping
>overseas the first spectrometers and waiting for them to
>call home and work with HPGe detectors (each being generally
>a unique personality) they have never seen; I also know the
>relief at the end of it.

Oh, what I wouldn't do to get my hands on the optical design
of those devices and some ideas about sourcing parts here. I
have worked with spectrophotometers for decades now, going
back to the mid 1980's. Some of it expensive, but all of it
only to commercial standards. I started using the Ocean
Optics (because they were CHEAP) as soon as they first came
out with something decent. (Most of my work was in the
visible, near UV, and near IR -- but for very different
applications.) I still have some decent setups here and I've
designed some devices that can be made for only a few
dollars, and wavelength calibrated for $8 more, so that high
school students could actually built their own real-world
equipment that could genuinely "do science" and meet
calibration standards. No intensity calibration, though,
sadly. That costs money to do. (Unless you have a suggestion
about how to do it on the cheap?)

>And the scales are simply not comparable; how do these
>people survive the wait is just beyond me, I guess.

I think few people understand just what this kind of team
work means inside, how much it changes who you are, and what
it means when the work is suddenly handed off and you scatter
to the winds. Perhaps actors doing a long-running play, like
Les Miserables, would understand when the play breaks up
(though that one never seems to.) It's years of hard work
building up a team that in the end works superbly together
and has learned how it must be that each person makes up for
the deficits of each other, while capitalizing on their
strengths, into a whole unit that from the outside is totally
functional and complete.... only to have it dismantled
suddenly at the end. Or, at least, the serious threat of it.
All that has been so hard-won....

I feel for all here.

Jon

On Mon, 06 Aug 2012 21:26:55 -0400, Walter Banks
<walter@bytecraft.com> wrote:

>Jon Kirwan wrote:
>
>> On Mon, 06 Aug 2012 16:15:32 +1000, Don McKenzie <5V@2.5A>
>> wrote:
>>
>> >Been there, done that :-)
>> >
>> >http://www.abc.net.au/news/2012-08-06/nasa-celebrates-successful-mars-landing/4180454
>>
>> I started watching the NASA channel about 4 hours ago and
>> stayed with it. (Still watching, while they are doing the
>> news conference event and just finished congradulating each
>> member of the EDL team (entry, descent, and landing.)
>>
>> Australia was part of this success, as well -- at least in
>> terms of participating in the very much needed communications
>> portions.
>>
>> What impresses me the most is that this trip was about 350
>> million miles, ending in a tight coordination with two
>> orbiting satellites, the ODY and MRO, and deploying novel
>> technologies to land a 1 ton vehicle (if I heard correct.)
>> Hard to believe that all of this could come together as well
>> as it did.
>
>I like many watch the landing  coverage. There are two
>things that really impressed me.
>
>1) The navigation to get them there on a really small landing
>    footprint
>
>2) With all of the technology in the systems to land this
>successfully, one number still is impressive. There were still
>250 single point possible failures. The math against it working
>was astronomical. If there was anyone involved reading
>this I am all ears and you have my congratulations.
>
>Listing to the systems readout after the landing showed it
>almost everything was nominal.
>
>Congratulations all

Of all those single points of failure, the ones that worried
me the most were the pyros. You can test a lot of things --
like the 65,000 pounds of force the parachute had to bear.
But you can't test the ACTUAL pyros you will use. No matter
what you do, the ones you place in there can't have been
tested. We know how to make explosives of great uniformity,
of course. But all of that has to go into a system and it
must fire exactly correctly, under buffeting circumstances,
without a single point of failure in a single pyro. Just one
and that is it. Not that the rest wasn't also difficult. But
some of the things, since as the novel use of an imbalance in
weight distribution in order to permit direction control
during entry, can have errors in one part of the software be
compensated by the outer control loop in another part. So
even there, there is a backup hope. But the pyros either
work, or don't. That's what I was watching mostly for, though
the rest was also sincerely knuckle-whitening as well.

Jon

On Mon, 6 Aug 2012 12:50:50 -0700 (PDT), dp <dp@tgi-sci.com> wrote:

>On Aug 6, 9:43 am, Jon Kirwan <j...@infinitefactors.org> wrote:
>> ...
>> What impresses me the most is that this trip was about 350
>> million miles, ending in a tight coordination with two
>> orbiting satellites, the ODY and MRO, and deploying novel
>> technologies to land a 1 ton vehicle (if I heard correct.)
>> Hard to believe that all of this could come together as well
>> as it did.
>>
>> Jon
>
>Same feelings here - very well done. I just cannot imagine
>how tense it must have been for the people (person?) whose
>baby this is; I know I have had my tense moments shipping
>overseas the first spectrometers and waiting for them to
>call home and work with HPGe detectors (each being generally
>a unique personality) they have never seen; I also know the
>relief at the end of it.
>And the scales are simply not comparable; how do these
>people survive the wait is just beyond me, I guess.
>

I have met some of these people, and i couldn't tell the difference in a
few moments talking to them.  Just the same they seem to be made of
sterner stuff than Dale six-pack.

>Dimiter
>
>------------------------------------------------------
>Dimiter Popoff               Transgalactic Instruments
>
>http://www.tgi-sci.com
>------------------------------------------------------
>http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/
>

In article <dcu028127ggnbr00tf8ka6hhpdgr9omftj@4ax.com>, 
jonk@infinitefactors.org says...
> 
> On Mon, 06 Aug 2012 21:26:55 -0400, Walter Banks
> <walter@bytecraft.com> wrote:
> 
> >Jon Kirwan wrote:
> >
> >> On Mon, 06 Aug 2012 16:15:32 +1000, Don McKenzie <5V@2.5A>
> >> wrote:
> >>
> >> >Been there, done that :-)
> >> >
> >> >http://www.abc.net.au/news/2012-08-06/nasa-celebrates-successful-mars-landing/4180454
> >>
> >> I started watching the NASA channel about 4 hours ago and
> >> stayed with it. (Still watching, while they are doing the
> >> news conference event and just finished congradulating each
> >> member of the EDL team (entry, descent, and landing.)
> >>
> >> Australia was part of this success, as well -- at least in
> >> terms of participating in the very much needed communications
> >> portions.
> >>
> >> What impresses me the most is that this trip was about 350
> >> million miles, ending in a tight coordination with two
> >> orbiting satellites, the ODY and MRO, and deploying novel
> >> technologies to land a 1 ton vehicle (if I heard correct.)
> >> Hard to believe that all of this could come together as well
> >> as it did.
> >
> >I like many watch the landing  coverage. There are two
> >things that really impressed me.
> >
> >1) The navigation to get them there on a really small landing
> >    footprint
> >
> >2) With all of the technology in the systems to land this
> >successfully, one number still is impressive. There were still
> >250 single point possible failures. The math against it working
> >was astronomical. If there was anyone involved reading
> >this I am all ears and you have my congratulations.
> >
> >Listing to the systems readout after the landing showed it
> >almost everything was nominal.
> >
> >Congratulations all
> 
> Of all those single points of failure, the ones that worried
> me the most were the pyros. You can test a lot of things --
> like the 65,000 pounds of force the parachute had to bear.
> But you can't test the ACTUAL pyros you will use. No matter
> what you do, the ones you place in there can't have been
> tested. We know how to make explosives of great uniformity,
> of course. But all of that has to go into a system and it
> must fire exactly correctly, under buffeting circumstances,
> without a single point of failure in a single pyro. Just one
> and that is it. Not that the rest wasn't also difficult. But
> some of the things, since as the novel use of an imbalance in
> weight distribution in order to permit direction control
> during entry, can have errors in one part of the software be
> compensated by the outer control loop in another part. So
> even there, there is a backup hope. But the pyros either
> work, or don't. That's what I was watching mostly for, though
> the rest was also sincerely knuckle-whitening as well.
> 
However, you can have redundancy in some types of pyros such as wire
cutters and other release mechanisms.  Whether such redundancy is worth
the extra pyro weight, cabling and switching is a matter for experts
to decide.


Mark Borgerson

In article <a8b09dF2tcU1@mid.individual.net>, 5V@2.5A says...
> 
> On 07-Aug-12 8:13 AM, Jordan wrote:
> >
> >
> >> http://www.abc.net.au/news/2012-08-06/nasa-celebrates-successful-mars-landing/4180454
> >>
> >
> > Great achievement, but have we forgotten something?
> > I was surprised when I mentioned to some friends that there have been successful landings on Mars since at least 1976 -
> > they were astonished and disbelieving.
> 
> Try and get people to believe that the Concord and 747 first flew in 1969, or that the B52 proto took to the air in 1952.
> 
> BTW The B52 is still a current work horse.
> Only 6 new heads and 3 new handles. :-)

Right up there is the first flight of the A-12 (predecessor to the SR-
71) in 1962.  Of course, only a limited number of people really knew 
about it at the time!   ;-)

Mark Borgerson

Don McKenzie <5V@2.5A> wrote in
news:a895o7Fa95U1@mid.individual.net: 

> 
> Been there, done that :-)
> 
> http://www.abc.net.au/news/2012-08-06/nasa-celebrates-succes
> sful-mars-landing/4180454 
> 
> 


More news here, and predictions about rocks.

http://www.theonion.com/articles/nasa-now-almost-positive-mars-
is-rocky,29069/

On Tue, 7 Aug 2012 05:51:28 +0000 (UTC), Geoff
<public@email.com> wrote:

>Don McKenzie <5V@2.5A> wrote in
>news:a895o7Fa95U1@mid.individual.net: 
>
>> 
>> Been there, done that :-)
>> 
>> http://www.abc.net.au/news/2012-08-06/nasa-celebrates-succes
>> sful-mars-landing/4180454 
>> 
>> 
>
>
>More news here, and predictions about rocks.
>
>http://www.theonion.com/articles/nasa-now-almost-positive-mars-
>is-rocky,29069/

Yeah, right. The Onion. Pure tongue-in-cheek.

Jon

On Tue, 07 Aug 2012 08:13:26 +1000, Jordan <jordan@koora.com> wrote:

>
>
>> http://www.abc.net.au/news/2012-08-06/nasa-celebrates-successful-mars-landing/4180454
>>
>
>Great achievement, but have we forgotten something?
>I was surprised when I mentioned to some friends that there have been 
>successful landings on Mars since at least 1976 - they were astonished 
>and disbelieving.

Apparently the first pictures from the surface of Mars were taken by
Mars 3 in 1971, so successful landings happened a few years earlier.

On Aug 7, 5:11 am, Jon Kirwan <j...@infinitefactors.org> wrote:
> ...(Most of my work was in the
> visible, near UV, and near IR -- but for very different
> applications.) I still have some decent setups here and I've
> designed some devices that can be made for only a few
> dollars, and wavelength calibrated for $8 more, so that high
> school students could actually built their own real-world
> equipment that could genuinely "do science" and meet
> calibration standards. No intensity calibration, though,
> sadly. That costs money to do. (Unless you have a suggestion
> about how to do it on the cheap?)

Oh no, I could not possibly have a suggestion. My spectrometers
don't seem to have an overlapping wavelength range with yours,
mine are xray/gamma. I am practically clueless when it comes to
those in the UV and below range, mine generally count single
photons.
Efficiency calibration is costly on those for gamma, too,
though - the calibration source costs thousands. The rest, hm,
has become much less expensive since the release of the
netmca-3 (one can still spend tens of thousands on it but
does not have to any longer).
I would be curious what gamma spectrometry the thing is
carrying on board, too (if any, but likely so). Unlikely
HPGe, but then who knows, Mars is a cold place, they may
have figured some practical way to cool things down to
about liquid nitrogen.

Dimiter

------------------------------------------------------
Dimiter Popoff               Transgalactic Instruments

http://www.tgi-sci.com
------------------------------------------------------
http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/

On Mon, 6 Aug 2012 22:23:41 -0700, Mark Borgerson <mborgerson@comcast.net>
wrote:

>In article <a8b09dF2tcU1@mid.individual.net>, 5V@2.5A says...
>> 
>> On 07-Aug-12 8:13 AM, Jordan wrote:
>> >
>> >
>> >> http://www.abc.net.au/news/2012-08-06/nasa-celebrates-successful-mars-landing/4180454
>> >>
>> >
>> > Great achievement, but have we forgotten something?
>> > I was surprised when I mentioned to some friends that there have been successful landings on Mars since at least 1976 -
>> > they were astonished and disbelieving.
>> 
>> Try and get people to believe that the Concord and 747 first flew in 1969, or that the B52 proto took to the air in 1952.
>> 
>> BTW The B52 is still a current work horse.
>> Only 6 new heads and 3 new handles. :-)
>
>Right up there is the first flight of the A-12 (predecessor to the SR-
>71) in 1962.  Of course, only a limited number of people really knew 
>about it at the time!   ;-)

It didn't take long before the A-12 became public knowledge.  Revel even had
accurate models of it, and the D-21 drone, within a couple of years.  They did
a much better job of covering up the B2 project.

On 2012-08-07, Sylvia Else <sylvia@not.here.invalid> wrote:
> On 7/08/2012 8:56 AM, Grant Edwards wrote:

>> The commentators kept yammering on about how there was "zero margin
>> for error", and how "absolutely everything has to work right".
>>
>> Really?  A design with _zero_ safety margin?  Who signs off on a
>> system design or mission plan like that?
>>
>> I'm pretty sure that the "absolutely everything has to work right" is
>> also bullshit.  I heard several people who seemd know know which way
>> was up talking about redundancy in the hardware design, the software
>> design, and in the mission planning itself.
>
> Even the animated video of the skycrane clearly shows the rockets in 
> pairs, with only one of each pair in use.

Same for the attitude thrusters on descent stage used to steer during
the pre-parachute entry phase.

-- 
Grant Edwards               grant.b.edwards        Yow! I'm pretending I'm
                                  at               pulling in a TROUT!  Am I
                              gmail.com            doing it correctly??

Grant Edwards wrote:

> On 2012-08-06, Don McKenzie <5V@2.5A> wrote:
>
> > Been there, done that :-)
> >
> > http://www.abc.net.au/news/2012-08-06/nasa-celebrates-successful-mars-landing/4180454
>
> I thought the over-hyped commentary during the landing and especially
> in pre-landing videos (like the "Seven Minutes of Terror") was
> embarassing and made the design engineers and mission planners sound
> incompetent.
>
> The commentators kept yammering on about how there was "zero margin
> for error", and how "absolutely everything has to work right".
>
> Really?  A design with _zero_ safety margin?  Who signs off on a
> system design or mission plan like that?
>
> I'm pretty sure that the "absolutely everything has to work right" is
> also bullshit.  I heard several people who seemd know know which way
> was up talking about redundancy in the hardware design, the software
> design, and in the mission planning itself.

There was certainly lots of redundancy. One number that is still
impressive was that with all of the redundancy NASA identified about
250 remaining single point possible failures. The math on that many
series terms makes the comment understandable.

w..

On Tue, 7 Aug 2012 05:23:52 -0700 (PDT), dp <dp@tgi-sci.com>
wrote:

>On Aug 7, 5:11�am, Jon Kirwan <j...@infinitefactors.org> wrote:
>> ...(Most of my work was in the
>> visible, near UV, and near IR -- but for very different
>> applications.) I still have some decent setups here and I've
>> designed some devices that can be made for only a few
>> dollars, and wavelength calibrated for $8 more, so that high
>> school students could actually built their own real-world
>> equipment that could genuinely "do science" and meet
>> calibration standards. No intensity calibration, though,
>> sadly. That costs money to do. (Unless you have a suggestion
>> about how to do it on the cheap?)
>
>Oh no, I could not possibly have a suggestion. My spectrometers
>don't seem to have an overlapping wavelength range with yours,
>mine are xray/gamma. I am practically clueless when it comes to
>those in the UV and below range, mine generally count single
>photons.

For all those reasons, that is why I would LOVE to see the
"optics" (and the schematics, as well.) Totally new area for
me to learn about. In my region, it's all about electron
transitions -- and no molecular dissassociation.

I'd expect you'd count single photons at those energies --
just one probably creates quite a shower to deal with. I'd
like to know, in practice, how one measures the energy.

Also, in space there is a serious problem with "brown crud",
which is smashed, charged particles that come from the
satellite's own fabrication scattered into space, which
because it is charged comes back to the spacecraft at some
later time, but sticks elsewhere (not where you want it.) I
don't know if there is a problem with this on Mars -- there
is an atmosphere of sorts. But I'm curious just the same if
there is an accumulation problem and how it is dealt with.

>Efficiency calibration is costly on those for gamma, too,
>though - the calibration source costs thousands. The rest, hm,
>has become much less expensive since the release of the
>netmca-3 (one can still spend tens of thousands on it but
>does not have to any longer).

Now THAT I totally believe. I probably couldn't afford it.
But I still could learn.

>I would be curious what gamma spectrometry the thing is
>carrying on board, too (if any, but likely so). Unlikely
>HPGe, but then who knows, Mars is a cold place, they may
>have figured some practical way to cool things down to
>about liquid nitrogen.

Well, they certainly don't have much atmospheric pressure to
worry about.

Which reminds me of another thing. How do they convect the
internally generated heat away. I recall hearing about
multiple power systems, operating around 32V at near 2A. More
than one. This power must be convected/conducted away -- no
way they want to radiate it. I wonder if they push it
(costing more heat) towards a vane or arm and drag it around
on the surface to get rid of it? The atmosphere won't help
much.

Jon

On Aug 7, 3:19 pm, Jon Kirwan <j...@infinitefactors.org> wrote:
> On Tue, 7 Aug 2012 05:23:52 -0700 (PDT), dp <d...@tgi-sci.com>
> wrote:
>
>
>
>
>
> >On Aug 7, 5:11 am, Jon Kirwan <j...@infinitefactors.org> wrote:
> >> ...(Most of my work was in the
> >> visible, near UV, and near IR -- but for very different
> >> applications.) I still have some decent setups here and I've
> >> designed some devices that can be made for only a few
> >> dollars, and wavelength calibrated for $8 more, so that high
> >> school students could actually built their own real-world
> >> equipment that could genuinely "do science" and meet
> >> calibration standards. No intensity calibration, though,
> >> sadly. That costs money to do. (Unless you have a suggestion
> >> about how to do it on the cheap?)
>
> >Oh no, I could not possibly have a suggestion. My spectrometers
> >don't seem to have an overlapping wavelength range with yours,
> >mine are xray/gamma. I am practically clueless when it comes to
> >those in the UV and below range, mine generally count single
> >photons.
>
> For all those reasons, that is why I would LOVE to see the
> "optics" (and the schematics, as well.) Totally new area for
> me to learn about. In my region, it's all about electron
> transitions -- and no molecular dissassociation.
>
> I'd expect you'd count single photons at those energies --
> just one probably creates quite a shower to deal with. I'd
> like to know, in practice, how one measures the energy.
>
> Also, in space there is a serious problem with "brown crud",
> which is smashed, charged particles that come from the
> satellite's own fabrication scattered into space, which
> because it is charged comes back to the spacecraft at some
> later time, but sticks elsewhere (not where you want it.) I
> don't know if there is a problem with this on Mars -- there
> is an atmosphere of sorts. But I'm curious just the same if
> there is an accumulation problem and how it is dealt with.
>
> >Efficiency calibration is costly on those for gamma, too,
> >though - the calibration source costs thousands. The rest, hm,
> >has become much less expensive since the release of the
> >netmca-3 (one can still spend tens of thousands on it but
> >does not have to any longer).
>
> Now THAT I totally believe. I probably couldn't afford it.
> But I still could learn.
>
> >I would be curious what gamma spectrometry the thing is
> >carrying on board, too (if any, but likely so). Unlikely
> >HPGe, but then who knows, Mars is a cold place, they may
> >have figured some practical way to cool things down to
> >about liquid nitrogen.
>
> Well, they certainly don't have much atmospheric pressure to
> worry about.
>
> Which reminds me of another thing. How do they convect the
> internally generated heat away. I recall hearing about
> multiple power systems, operating around 32V at near 2A. More
> than one. This power must be convected/conducted away -- no
> way they want to radiate it. I wonder if they push it
> (costing more heat) towards a vane or arm and drag it around
> on the surface to get rid of it?

The atmosphere won't help much.

Why not?  Thermal conductivity of air is pretty much constant till you
get below 1 Torr or so.  Wiki says the mean pressure on mars is about
0.1 psi, which is ~5 torr.

Re spectrometer calibration:  We had this "black body" source. (from
Ortec?)  That could be used for intensity calibration.  PITA though.

But maybe you could do something on the cheap with a tungsten light
bulb.

George H.
>
> Jon- Hide quoted text -
>
> - Show quoted text -

On Tue, 07 Aug 2012 12:19:47 -0700, Jon Kirwan
<jonk@infinitefactors.org> wrote:

>Which reminds me of another thing. How do they convect the
>internally generated heat away. I recall hearing about
>multiple power systems, operating around 32V at near 2A. More
>than one. This power must be convected/conducted away -- no
>way they want to radiate it. I wonder if they push it
>(costing more heat) towards a vane or arm and drag it around
>on the surface to get rid of it? The atmosphere won't help
>much.

They seem to worry more about distributing the heat, rather than
radiating it:
<http://mars.jpl.nasa.gov/msl/multimedia/interactives/learncuriosity/>
(Click on the arrows until it shows "body").

   The power system, which looks like its "tail," flows 
   excess heat into the body to keep the computer "brains," 
   avionics, instrument electronics, and interior instruments 
   (SAM and CheMin) warm in the extremely cold Martian 
   temperatures.

-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

On Mon, 6 Aug 2012 22:56:36 +0000 (UTC), Grant Edwards
<invalid@invalid.invalid> wrote:

>The blockbuster-movie-preview-preview-style-over-hyped-bullshit just
>detracted from what in reality was an utterly brilliant job.  Even
>though nothing _did_ go wrong (AFAICT), and they hit center of the
>bullseye, I'm confident that there was both redundancy and margin for
>error designed/built into almost everything.

Watching the control room feed, it seemed to me that there was a
communication bobble surrounding the parachute deployment.  The
conversation wasn't clear, but from what little I could make out I had
the impression that there was an unexpected telemetry gap that spooked
them for a few moments.

George

On Tue, 7 Aug 2012 12:42:56 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

>On Aug 7, 3:19�pm, Jon Kirwan <j...@infinitefactors.org> wrote:
>> On Tue, 7 Aug 2012 05:23:52 -0700 (PDT), dp <d...@tgi-sci.com>
>> wrote:
>>
>>
>>
>>
>>
>> >On Aug 7, 5:11 am, Jon Kirwan <j...@infinitefactors.org> wrote:
>> >> ...(Most of my work was in the
>> >> visible, near UV, and near IR -- but for very different
>> >> applications.) I still have some decent setups here and I've
>> >> designed some devices that can be made for only a few
>> >> dollars, and wavelength calibrated for $8 more, so that high
>> >> school students could actually built their own real-world
>> >> equipment that could genuinely "do science" and meet
>> >> calibration standards. No intensity calibration, though,
>> >> sadly. That costs money to do. (Unless you have a suggestion
>> >> about how to do it on the cheap?)
>>
>> >Oh no, I could not possibly have a suggestion. My spectrometers
>> >don't seem to have an overlapping wavelength range with yours,
>> >mine are xray/gamma. I am practically clueless when it comes to
>> >those in the UV and below range, mine generally count single
>> >photons.
>>
>> For all those reasons, that is why I would LOVE to see the
>> "optics" (and the schematics, as well.) Totally new area for
>> me to learn about. In my region, it's all about electron
>> transitions -- and no molecular dissassociation.
>>
>> I'd expect you'd count single photons at those energies --
>> just one probably creates quite a shower to deal with. I'd
>> like to know, in practice, how one measures the energy.
>>
>> Also, in space there is a serious problem with "brown crud",
>> which is smashed, charged particles that come from the
>> satellite's own fabrication scattered into space, which
>> because it is charged comes back to the spacecraft at some
>> later time, but sticks elsewhere (not where you want it.) I
>> don't know if there is a problem with this on Mars -- there
>> is an atmosphere of sorts. But I'm curious just the same if
>> there is an accumulation problem and how it is dealt with.
>>
>> >Efficiency calibration is costly on those for gamma, too,
>> >though - the calibration source costs thousands. The rest, hm,
>> >has become much less expensive since the release of the
>> >netmca-3 (one can still spend tens of thousands on it but
>> >does not have to any longer).
>>
>> Now THAT I totally believe. I probably couldn't afford it.
>> But I still could learn.
>>
>> >I would be curious what gamma spectrometry the thing is
>> >carrying on board, too (if any, but likely so). Unlikely
>> >HPGe, but then who knows, Mars is a cold place, they may
>> >have figured some practical way to cool things down to
>> >about liquid nitrogen.
>>
>> Well, they certainly don't have much atmospheric pressure to
>> worry about.
>>
>> Which reminds me of another thing. How do they convect the
>> internally generated heat away. I recall hearing about
>> multiple power systems, operating around 32V at near 2A. More
>> than one. This power must be convected/conducted away -- no
>> way they want to radiate it. I wonder if they push it
>> (costing more heat) towards a vane or arm and drag it around
>> on the surface to get rid of it?
>
>The atmosphere won't help much.
>
>Why not?  Thermal conductivity of air is pretty much constant till you
>get below 1 Torr or so.  Wiki says the mean pressure on mars is about
>0.1 psi, which is ~5 torr.

Good point.

What triggered my comment is remembering that heat buildup
was most certainly a problem during broadcasts with the high
gain antenna system towards Earth. They can't operate it
continuously, if I recall correctly. Made me wonder about the
rest. I had also remembered the case of satellites and "knew"
that the Martian atmosphere could be as little as a few tens
of Pascals. So I projected that heat accumulation may be a
problem. Apparently, it isn't.

I gather your point. To understand it more fully, I need to
think more closely about mean-free-path, I guess. Thanks.

>Re spectrometer calibration:  We had this "black body" source. (from
>Ortec?)  That could be used for intensity calibration.  PITA though.

The problem for students is that they cannot afford the $800
it takes to get a $8 tungsten bulb calibrated. (It can cost a
lot more than that, too.) Then they need to set up a careful
station for making the calibration. It's just plain too
expensive to do. And I don't know a way around it. Wavelength
calibration is CHEAP!! $12 buys a merc-argon calibration
lamp, which fires up with the Argon first (for about a minute
or two where you get some very nice Argon lines in the longer
wavelengths) and then the Mercury kicks in and dominates with
it's lines. A couple of well-timed snapshots and you've got
enough (with software) to completely calibrate your pixel
positions in a cheap ($10) megapixel camera.

I'd LOVE to figure out a cheap intensity calibration setup,
though. So would a lot of other people, I suppose.

>But maybe you could do something on the cheap with a tungsten light
>bulb.

But that's the problem. I can get a cheap tungsten lamp. They
are VERY CHEAP. In fact, the EXACT SAME ONE I would buy,
calibrated, is dirt cheap uncalibrated. It is the calibration
data that comes with a newly calibrated lamp that costs so
darned much. It needs to be traceable to standards. And you
pay for that. Plus, you need an expensive power supply to
operate it (0.1% current control is standard.) And it ages,
too. Within 100 hours or so, it's drifted enough that it
needs recalibration.

Thanks,
Jon

"Jon Kirwan" <jonk@infinitefactors.org> wrote in message 
news:e0q228956bpb829qehome35ab6mcfoaps6@4ax.com...
> Which reminds me of another thing. How do they convect the
> internally generated heat away. I recall hearing about
> multiple power systems, operating around 32V at near 2A. More
> than one. This power must be convected/conducted away -- no
> way they want to radiate it. I wonder if they push it
> (costing more heat) towards a vane or arm and drag it around
> on the surface to get rid of it? The atmosphere won't help
> much.

In addition to what the others have said, keep in mind the thing floated 
through space for six months -- you can't cool Pu238 down, so *all* that 
heat had to be dissipated, as radiation, from the backshell and heat shield, 
into space.  The vehicle itself may've had cooling to the shell, but the 
shell still had to dissipate it.

Tim

-- 
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms 

On 8/8/2012 7:04 AM, Jon Kirwan wrote:

>>>
>>> Which reminds me of another thing. How do they convect the
>>> internally generated heat away. I recall hearing about
>>> multiple power systems, operating around 32V at near 2A. More
>>> than one. This power must be convected/conducted away -- no
>>> way they want to radiate it. I wonder if they push it
>>> (costing more heat) towards a vane or arm and drag it around
>>> on the surface to get rid of it?
>>
>> The atmosphere won't help much.
>>
>> Why not?  Thermal conductivity of air is pretty much constant till you
>> get below 1 Torr or so.  Wiki says the mean pressure on mars is about
>> 0.1 psi, which is ~5 torr.
>
> Good point.
>

In earth atmosphere, I understand most heat above around 300K ( 'room' 
temp ) is carried by radiation and convection.  Conduction is a minor part.

No idea what convection is like at 5 torr in a CO2 atmosphere, but I 
suspect its a lot lower.

-- 
Regards,

Adrian Jansen           adrianjansen at internode dot on dot net
Note reply address is invalid, convert address above to machine form.

On Tue, 7 Aug 2012 17:59:42 -0500, "Tim Williams"
<tmoranwms@charter.net> wrote:

>"Jon Kirwan" <jonk@infinitefactors.org> wrote in message 
>news:e0q228956bpb829qehome35ab6mcfoaps6@4ax.com...
>> Which reminds me of another thing. How do they convect the
>> internally generated heat away. I recall hearing about
>> multiple power systems, operating around 32V at near 2A. More
>> than one. This power must be convected/conducted away -- no
>> way they want to radiate it. I wonder if they push it
>> (costing more heat) towards a vane or arm and drag it around
>> on the surface to get rid of it? The atmosphere won't help
>> much.
>
>In addition to what the others have said, keep in mind the thing floated 
>through space for six months -- you can't cool Pu238 down, so *all* that 
>heat had to be dissipated, as radiation, from the backshell and heat shield, 
>into space.  The vehicle itself may've had cooling to the shell, but the 
>shell still had to dissipate it.

The shell is now gone. I was curious about Curiosity, itself.

You can only emit so many watts into space via radiation
given a surface area: A*e*s*T^4. There is no convection or
conduction, of course. But as George pointed out, the
existing atmosphere likely provides some relief here.

But speaking only about radiation outward, even with e at 0.9
(it usually isn't -- but I've measured silicon carbide, for
example, at around .9), this works out to about 490 watts/m^2
of radiating surface with e=0.9 and T=40C. (Anodized aluminum
is about 0.75.)

The problem is compounded by the fact that the same (or
nearby) surfaces will absorb insolation. On Mars, this is
about 1/2 the amount Earth gets, per m^2. But the Gale Crater
is at 4.5 degrees south latitude (basically on the equator)
and so it would experience, I think, on the order of 1362/2
or 680 Watts/m^2 of insolation, ignoring the albedo of the
atmosphere (which probably [but I don't really know] doesn't
reflect or thermalize a lot away before it reaches ground
level.) There would also be differential heating (sides where
sun is striking vs other sides), too.

All this poses some interesting questions, at least.

Cyclic heating and cooling can seriously cut down on the
lifetime of instrumentation, structures, solar panels, and so
on. UV radiation, also, is energetic enough to break polymer
bonds such as C-C and C-O, as well as many functional groups.
Obviously, still higher radiation from the sun causes
ionization, photon excitation, and atomic displacement. I
remember also that tests on a CCD not so long ago showed that
100 Rads generated hot spots on 10% of the CCD exceeding the
limits of an 8 bit ADC.

The ISS, for example, used hundreds of kilograms of silicon
purely for thermal protection. 

I'm curious how these issues were examined, explored, and
either discounted or solved. Anyone know the details?

Thanks,
Jon

On Wed, 08 Aug 2012 09:42:05 +1000, Adrian Jansen
<adrian@qq.vv.net> wrote:

>On 8/8/2012 7:04 AM, Jon Kirwan wrote:
>
>>>>
>>>> Which reminds me of another thing. How do they convect the
>>>> internally generated heat away. I recall hearing about
>>>> multiple power systems, operating around 32V at near 2A. More
>>>> than one. This power must be convected/conducted away -- no
>>>> way they want to radiate it. I wonder if they push it
>>>> (costing more heat) towards a vane or arm and drag it around
>>>> on the surface to get rid of it?
>>>
>>> The atmosphere won't help much.
>>>
>>> Why not?  Thermal conductivity of air is pretty much constant till you
>>> get below 1 Torr or so.  Wiki says the mean pressure on mars is about
>>> 0.1 psi, which is ~5 torr.
>>
>> Good point.
>>
>
>In earth atmosphere, I understand most heat above around 300K ( 'room' 
>temp ) is carried by radiation and convection.  Conduction is a minor part.
>
>No idea what convection is like at 5 torr in a CO2 atmosphere, but I 
>suspect its a lot lower.

Then that begs the question, again. Perhaps George spoke too
soon.

I'll go dig. I'm ignorant and don't like the feeling.

Jon

Adrian Jansen wrote:
> 
> On 8/8/2012 7:04 AM, Jon Kirwan wrote:
> 
> >>>
> >>> Which reminds me of another thing. How do they convect the
> >>> internally generated heat away. I recall hearing about
> >>> multiple power systems, operating around 32V at near 2A. More
> >>> than one. This power must be convected/conducted away -- no
> >>> way they want to radiate it. I wonder if they push it
> >>> (costing more heat) towards a vane or arm and drag it around
> >>> on the surface to get rid of it?
> >>
> >> The atmosphere won't help much.
> >>
> >> Why not?  Thermal conductivity of air is pretty much constant till you
> >> get below 1 Torr or so.  Wiki says the mean pressure on mars is about
> >> 0.1 psi, which is ~5 torr.
> >
> > Good point.
> >
> 
> In earth atmosphere, I understand most heat above around 300K ( 'room'
> temp ) is carried by radiation and convection.  Conduction is a minor part.
> 
> No idea what convection is like at 5 torr in a CO2 atmosphere, but I
> suspect its a lot lower.
> 

Thermal conduction is independent of pressure until the mean free path
becomes comparable to the dimension of the object, or to the gap between
objects.  A 5-torr atmosphere is as good as a 760 torr one for
conductive cooling.  

Convection is more complicated--as pressure increases, you win by having
more air mass per unit volume, but you lose by the diffusion length
getting shorter--you can't heat as much volume in a given time.

Cheers

Phil Hobbs

-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

"Jon Kirwan" <jonk@infinitefactors.org> wrote in message 
news:eb8328ddvil626apeui0pq7jnprtcgbbp5@4ax.com...
>>In addition to what the others have said, keep in mind the thing floated
>>through space for six months -- you can't cool Pu238 down, so *all* that
>>heat had to be dissipated, as radiation, from the backshell and heat 
>>shield,
>>into space.  The vehicle itself may've had cooling to the shell, but the
>>shell still had to dissipate it.
>
>The shell is now gone. I was curious about Curiosity, itself.

Point being, it probably had a harder time dissipating in flight than on the 
surface...  Real question is, is the ratio of surface areas reasonable for 
the respective conditions?  The shell was flat and surrounded by vacuum, but 
large; the rover chassis is smaller, but has more surface area, and has a 
little air around it.

I've got a vacuum tube that's rated for flight up to 80,000 feet, derated by 
half at that altitude (only 15W, it's 6L6GC sized).  Mars is roughly in that 
range, or up to 100kft, I forget where exactly.  That's a 50% derating for 
similar pressure, but the tube's operating temperature is way higher (peak 
envelope temperature 300C!), so radiation is dominant.  At normaler 
temperatures (40-60C), I'd guess 80-90% derating would be reasonable, 
relative to STP figures of dissipation.

>But speaking only about radiation outward, even with e at 0.9
>(it usually isn't -- but I've measured silicon carbide, for
>example, at around .9), this works out to about 490 watts/m^2
>of radiating surface with e=0.9 and T=40C. (Anodized aluminum
>is about 0.75.)

So again, it comes down to surface area, and how they distribute the heat.

Wouldn't be surprised if they have an inner loop around the RTG, to burn off 
most of the power at a high temperature, and secondary loop(s) to keep the 
rest of the thing warm.  Extra temp on the RTG casing or whatever would do a 
fine job of bleeding off any extra heat the frame doesn't need; the casing's 
temperature will swing with demand, but that's fine because it's already 
designed to run warm or hot.

>The problem is compounded by the fact that the same (or
>nearby) surfaces will absorb insolation. On Mars, this is
>about 1/2 the amount Earth gets, per m^2. But the Gale Crater
>is at 4.5 degrees south latitude (basically on the equator)
>and so it would experience, I think, on the order of 1362/2
>or 680 Watts/m^2 of insolation, ignoring the albedo of the
>atmosphere (which probably [but I don't really know] doesn't
>reflect or thermalize a lot away before it reaches ground
>level.) There would also be differential heating (sides where
>sun is striking vs other sides), too.


If Curiosity had a bubble and a seat to sit in, I bet it would feel a lot 
like sitting in a parked car, on a cold winter's day, in bright daylight. 
When heat's trapped, it's warm, but not sweltering or anything; open the 
windows and you'll freeze your ass off (but that'd be convection, of 
course).

>Cyclic heating and cooling can seriously cut down on the
>lifetime of instrumentation, structures, solar panels, and so
>on. UV radiation, also, is energetic enough to break polymer
>bonds such as C-C and C-O, as well as many functional groups.
>Obviously, still higher radiation from the sun causes
>ionization, photon excitation, and atomic displacement. I
>remember also that tests on a CCD not so long ago showed that
>100 Rads generated hot spots on 10% of the CCD exceeding the
>limits of an 8 bit ADC.

On the upside, there's no oxygen to move in and latch onto said free 
radicals.

Even without oxygen, I wouldn't be surprised if weaker plastics end up 
shredded in a few years, much as they do here.

I'd expect they use an awful lot of epoxy composites, kapton film and kevlar 
and carbon fiber.  These are a whole lot more robust than the average nylon 
or rubber, and endure well even in harsh conditions.

Tim

-- 
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms 

On Tue, 07 Aug 2012 14:04:19 -0700, Jon Kirwan <jonk@infinitefactors.org>
wrote:

>On Tue, 7 Aug 2012 12:42:56 -0700 (PDT), George Herold
><gherold@teachspin.com> wrote:
>
>>On Aug 7, 3:19 pm, Jon Kirwan <j...@infinitefactors.org> wrote:
>>> On Tue, 7 Aug 2012 05:23:52 -0700 (PDT), dp <d...@tgi-sci.com>
>>> wrote:
>>>
>>>
>>>
>>>
>>>
>>> >On Aug 7, 5:11 am, Jon Kirwan <j...@infinitefactors.org> wrote:
>>> >> ...(Most of my work was in the
>>> >> visible, near UV, and near IR -- but for very different
>>> >> applications.) I still have some decent setups here and I've
>>> >> designed some devices that can be made for only a few
>>> >> dollars, and wavelength calibrated for $8 more, so that high
>>> >> school students could actually built their own real-world
>>> >> equipment that could genuinely "do science" and meet
>>> >> calibration standards. No intensity calibration, though,
>>> >> sadly. That costs money to do. (Unless you have a suggestion
>>> >> about how to do it on the cheap?)
>>>
>>> >Oh no, I could not possibly have a suggestion. My spectrometers
>>> >don't seem to have an overlapping wavelength range with yours,
>>> >mine are xray/gamma. I am practically clueless when it comes to
>>> >those in the UV and below range, mine generally count single
>>> >photons.
>>>
>>> For all those reasons, that is why I would LOVE to see the
>>> "optics" (and the schematics, as well.) Totally new area for
>>> me to learn about. In my region, it's all about electron
>>> transitions -- and no molecular dissassociation.
>>>
>>> I'd expect you'd count single photons at those energies --
>>> just one probably creates quite a shower to deal with. I'd
>>> like to know, in practice, how one measures the energy.
>>>
>>> Also, in space there is a serious problem with "brown crud",
>>> which is smashed, charged particles that come from the
>>> satellite's own fabrication scattered into space, which
>>> because it is charged comes back to the spacecraft at some
>>> later time, but sticks elsewhere (not where you want it.) I
>>> don't know if there is a problem with this on Mars -- there
>>> is an atmosphere of sorts. But I'm curious just the same if
>>> there is an accumulation problem and how it is dealt with.
>>>
>>> >Efficiency calibration is costly on those for gamma, too,
>>> >though - the calibration source costs thousands. The rest, hm,
>>> >has become much less expensive since the release of the
>>> >netmca-3 (one can still spend tens of thousands on it but
>>> >does not have to any longer).
>>>
>>> Now THAT I totally believe. I probably couldn't afford it.
>>> But I still could learn.
>>>
>>> >I would be curious what gamma spectrometry the thing is
>>> >carrying on board, too (if any, but likely so). Unlikely
>>> >HPGe, but then who knows, Mars is a cold place, they may
>>> >have figured some practical way to cool things down to
>>> >about liquid nitrogen.
>>>
>>> Well, they certainly don't have much atmospheric pressure to
>>> worry about.
>>>
>>> Which reminds me of another thing. How do they convect the
>>> internally generated heat away. I recall hearing about
>>> multiple power systems, operating around 32V at near 2A. More
>>> than one. This power must be convected/conducted away -- no
>>> way they want to radiate it. I wonder if they push it
>>> (costing more heat) towards a vane or arm and drag it around
>>> on the surface to get rid of it?
>>
>>The atmosphere won't help much.
>>
>>Why not?  Thermal conductivity of air is pretty much constant till you
>>get below 1 Torr or so.  Wiki says the mean pressure on mars is about
>>0.1 psi, which is ~5 torr.
>
>Good point.
>
>What triggered my comment is remembering that heat buildup
>was most certainly a problem during broadcasts with the high
>gain antenna system towards Earth. They can't operate it
>continuously, if I recall correctly. Made me wonder about the
>rest. I had also remembered the case of satellites and "knew"
>that the Martian atmosphere could be as little as a few tens
>of Pascals. So I projected that heat accumulation may be a
>problem. Apparently, it isn't.
>
>I gather your point. To understand it more fully, I need to
>think more closely about mean-free-path, I guess. Thanks.
>
>>Re spectrometer calibration:  We had this "black body" source. (from
>>Ortec?)  That could be used for intensity calibration.  PITA though.
>
>The problem for students is that they cannot afford the $800
>it takes to get a $8 tungsten bulb calibrated. (It can cost a
>lot more than that, too.) Then they need to set up a careful
>station for making the calibration. It's just plain too
>expensive to do. And I don't know a way around it. Wavelength
>calibration is CHEAP!! $12 buys a merc-argon calibration
>lamp, which fires up with the Argon first (for about a minute
>or two where you get some very nice Argon lines in the longer
>wavelengths) and then the Mercury kicks in and dominates with
>it's lines. A couple of well-timed snapshots and you've got
>enough (with software) to completely calibrate your pixel
>positions in a cheap ($10) megapixel camera.
>
>I'd LOVE to figure out a cheap intensity calibration setup,
>though. So would a lot of other people, I suppose.
>
>>But maybe you could do something on the cheap with a tungsten light
>>bulb.
>
>But that's the problem. I can get a cheap tungsten lamp. They
>are VERY CHEAP. In fact, the EXACT SAME ONE I would buy,
>calibrated, is dirt cheap uncalibrated. It is the calibration
>data that comes with a newly calibrated lamp that costs so
>darned much. It needs to be traceable to standards. And you
>pay for that. Plus, you need an expensive power supply to
>operate it (0.1% current control is standard.) And it ages,
>too. Within 100 hours or so, it's drifted enough that it
>needs recalibration.
>
>Thanks,
>Jon


It may be possible to start with a selection of calibrated LED sources
(kind of like the near IR ones used for light source & light meter used
for fiber optic cable measurements).  With a nice selection of say a dozen
wavelengths in the range of interest, it may become reasonably feasible.
With a decent calibration cycle as well.

Internet patent dated 7 August, 2012, all rights reserved.

?-)

On Tue, 07 Aug 2012 19:34:24 -0700, josephkk
<joseph_barrett@sbcglobal.net> wrote:

>On Tue, 07 Aug 2012 14:04:19 -0700, Jon Kirwan <jonk@infinitefactors.org>
>wrote:
>
>>On Tue, 7 Aug 2012 12:42:56 -0700 (PDT), George Herold
>><gherold@teachspin.com> wrote:
>>
>>>On Aug 7, 3:19 pm, Jon Kirwan <j...@infinitefactors.org> wrote:
>>>> On Tue, 7 Aug 2012 05:23:52 -0700 (PDT), dp <d...@tgi-sci.com>
>>>> wrote:
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> >On Aug 7, 5:11 am, Jon Kirwan <j...@infinitefactors.org> wrote:
>>>> >> ...(Most of my work was in the
>>>> >> visible, near UV, and near IR -- but for very different
>>>> >> applications.) I still have some decent setups here and I've
>>>> >> designed some devices that can be made for only a few
>>>> >> dollars, and wavelength calibrated for $8 more, so that high
>>>> >> school students could actually built their own real-world
>>>> >> equipment that could genuinely "do science" and meet
>>>> >> calibration standards. No intensity calibration, though,
>>>> >> sadly. That costs money to do. (Unless you have a suggestion
>>>> >> about how to do it on the cheap?)
>>>>
>>>> >Oh no, I could not possibly have a suggestion. My spectrometers
>>>> >don't seem to have an overlapping wavelength range with yours,
>>>> >mine are xray/gamma. I am practically clueless when it comes to
>>>> >those in the UV and below range, mine generally count single
>>>> >photons.
>>>>
>>>> For all those reasons, that is why I would LOVE to see the
>>>> "optics" (and the schematics, as well.) Totally new area for
>>>> me to learn about. In my region, it's all about electron
>>>> transitions -- and no molecular dissassociation.
>>>>
>>>> I'd expect you'd count single photons at those energies --
>>>> just one probably creates quite a shower to deal with. I'd
>>>> like to know, in practice, how one measures the energy.
>>>>
>>>> Also, in space there is a serious problem with "brown crud",
>>>> which is smashed, charged particles that come from the
>>>> satellite's own fabrication scattered into space, which
>>>> because it is charged comes back to the spacecraft at some
>>>> later time, but sticks elsewhere (not where you want it.) I
>>>> don't know if there is a problem with this on Mars -- there
>>>> is an atmosphere of sorts. But I'm curious just the same if
>>>> there is an accumulation problem and how it is dealt with.
>>>>
>>>> >Efficiency calibration is costly on those for gamma, too,
>>>> >though - the calibration source costs thousands. The rest, hm,
>>>> >has become much less expensive since the release of the
>>>> >netmca-3 (one can still spend tens of thousands on it but
>>>> >does not have to any longer).
>>>>
>>>> Now THAT I totally believe. I probably couldn't afford it.
>>>> But I still could learn.
>>>>
>>>> >I would be curious what gamma spectrometry the thing is
>>>> >carrying on board, too (if any, but likely so). Unlikely
>>>> >HPGe, but then who knows, Mars is a cold place, they may
>>>> >have figured some practical way to cool things down to
>>>> >about liquid nitrogen.
>>>>
>>>> Well, they certainly don't have much atmospheric pressure to
>>>> worry about.
>>>>
>>>> Which reminds me of another thing. How do they convect the
>>>> internally generated heat away. I recall hearing about
>>>> multiple power systems, operating around 32V at near 2A. More
>>>> than one. This power must be convected/conducted away -- no
>>>> way they want to radiate it. I wonder if they push it
>>>> (costing more heat) towards a vane or arm and drag it around
>>>> on the surface to get rid of it?
>>>
>>>The atmosphere won't help much.
>>>
>>>Why not?  Thermal conductivity of air is pretty much constant till you
>>>get below 1 Torr or so.  Wiki says the mean pressure on mars is about
>>>0.1 psi, which is ~5 torr.
>>
>>Good point.
>>
>>What triggered my comment is remembering that heat buildup
>>was most certainly a problem during broadcasts with the high
>>gain antenna system towards Earth. They can't operate it
>>continuously, if I recall correctly. Made me wonder about the
>>rest. I had also remembered the case of satellites and "knew"
>>that the Martian atmosphere could be as little as a few tens
>>of Pascals. So I projected that heat accumulation may be a
>>problem. Apparently, it isn't.
>>
>>I gather your point. To understand it more fully, I need to
>>think more closely about mean-free-path, I guess. Thanks.
>>
>>>Re spectrometer calibration:  We had this "black body" source. (from
>>>Ortec?)  That could be used for intensity calibration.  PITA though.
>>
>>The problem for students is that they cannot afford the $800
>>it takes to get a $8 tungsten bulb calibrated. (It can cost a
>>lot more than that, too.) Then they need to set up a careful
>>station for making the calibration. It's just plain too
>>expensive to do. And I don't know a way around it. Wavelength
>>calibration is CHEAP!! $12 buys a merc-argon calibration
>>lamp, which fires up with the Argon first (for about a minute
>>or two where you get some very nice Argon lines in the longer
>>wavelengths) and then the Mercury kicks in and dominates with
>>it's lines. A couple of well-timed snapshots and you've got
>>enough (with software) to completely calibrate your pixel
>>positions in a cheap ($10) megapixel camera.
>>
>>I'd LOVE to figure out a cheap intensity calibration setup,
>>though. So would a lot of other people, I suppose.
>>
>>>But maybe you could do something on the cheap with a tungsten light
>>>bulb.
>>
>>But that's the problem. I can get a cheap tungsten lamp. They
>>are VERY CHEAP. In fact, the EXACT SAME ONE I would buy,
>>calibrated, is dirt cheap uncalibrated. It is the calibration
>>data that comes with a newly calibrated lamp that costs so
>>darned much. It needs to be traceable to standards. And you
>>pay for that. Plus, you need an expensive power supply to
>>operate it (0.1% current control is standard.) And it ages,
>>too. Within 100 hours or so, it's drifted enough that it
>>needs recalibration.
>>
>>Thanks,
>>Jon
>
>It may be possible to start with a selection of calibrated LED sources
>(kind of like the near IR ones used for light source & light meter used
>for fiber optic cable measurements).  With a nice selection of say a dozen
>wavelengths in the range of interest, it may become reasonably feasible.
>With a decent calibration cycle as well.
>
>Internet patent dated 7 August, 2012, all rights reserved.

I know you were laughing. Don't. I've been there. I've
already built calibration LEDs. Not for the purpose of
calibrating visible wavelength spectrophotometers, though.
They were very special-purpose standard-candle devices
because dispersion isn't anything like a tungsten lamp and
alignment of the LED die severely limits practical use.

If you had ANY idea just how HARD it is to calibrate LEDs for
optical output....

First, you buy 1000 LEDs and request that they all come from
the same FAB and batch. They will need to be operated at an
elevated, controlled temperature when they are finally used,
so you set each one up to run at that temperature and then
continuously observe them for 200 hours of operation. In that
time, most of them will drift all over the place and will NOT
settle down entirely in that time. You throw those away.
Others will not drift all over but will drift way too fast to
be any good. Throw those away, too. Of the 10 or 15 LEDs left
in the batch that happen to have stabilized well enough in
200 hours of operation to appear to be useful, you go through
the trouble of cutting away the epoxy with precision tools
and then operating them some more while producing a
calibration table for each in their final module.

It's not cheap. Their wavelength skirts are wide, too. Now do
this for a variety of visible areas to produce what you are
talking about?

Tungsten gives nice coverage. Here's a calibration table I
got from Optronix for a 45W tungsten lamp (actually a 50W),
model 245M, using a standard distance away using a standard
optical arrangement. Filament must be vertical, current
controlled to 0.1%, etc. It gives an example of how many
points are sometimes used, though you can always pay for
more. Given the black body curve behavior, interpolation at
different points is manageable.

250,.000249
270,.00818
290,.00217
300,.00332
310,.00489
320,.00697
330,.00960
340,.0130
350,.0173
370,.0285
400,.0531
450,.118
500,.212
555,.337
600,.446
654.6,.574
700,.669
800,.830
900,.902
1050,.892
1100,.865

Jon

On Aug 7, 5:04 pm, Jon Kirwan <j...@infinitefactors.org> wrote:
> On Tue, 7 Aug 2012 12:42:56 -0700 (PDT), George Herold
>
>
>
>
>
> <gher...@teachspin.com> wrote:
> >On Aug 7, 3:19 pm, Jon Kirwan <j...@infinitefactors.org> wrote:
> >> On Tue, 7 Aug 2012 05:23:52 -0700 (PDT), dp <d...@tgi-sci.com>
> >> wrote:
>
> >> >On Aug 7, 5:11 am, Jon Kirwan <j...@infinitefactors.org> wrote:
> >> >> ...(Most of my work was in the
> >> >> visible, near UV, and near IR -- but for very different
> >> >> applications.) I still have some decent setups here and I've
> >> >> designed some devices that can be made for only a few
> >> >> dollars, and wavelength calibrated for $8 more, so that high
> >> >> school students could actually built their own real-world
> >> >> equipment that could genuinely "do science" and meet
> >> >> calibration standards. No intensity calibration, though,
> >> >> sadly. That costs money to do. (Unless you have a suggestion
> >> >> about how to do it on the cheap?)
>
> >> >Oh no, I could not possibly have a suggestion. My spectrometers
> >> >don't seem to have an overlapping wavelength range with yours,
> >> >mine are xray/gamma. I am practically clueless when it comes to
> >> >those in the UV and below range, mine generally count single
> >> >photons.
>
> >> For all those reasons, that is why I would LOVE to see the
> >> "optics" (and the schematics, as well.) Totally new area for
> >> me to learn about. In my region, it's all about electron
> >> transitions -- and no molecular dissassociation.
>
> >> I'd expect you'd count single photons at those energies --
> >> just one probably creates quite a shower to deal with. I'd
> >> like to know, in practice, how one measures the energy.
>
> >> Also, in space there is a serious problem with "brown crud",
> >> which is smashed, charged particles that come from the
> >> satellite's own fabrication scattered into space, which
> >> because it is charged comes back to the spacecraft at some
> >> later time, but sticks elsewhere (not where you want it.) I
> >> don't know if there is a problem with this on Mars -- there
> >> is an atmosphere of sorts. But I'm curious just the same if
> >> there is an accumulation problem and how it is dealt with.
>
> >> >Efficiency calibration is costly on those for gamma, too,
> >> >though - the calibration source costs thousands. The rest, hm,
> >> >has become much less expensive since the release of the
> >> >netmca-3 (one can still spend tens of thousands on it but
> >> >does not have to any longer).
>
> >> Now THAT I totally believe. I probably couldn't afford it.
> >> But I still could learn.
>
> >> >I would be curious what gamma spectrometry the thing is
> >> >carrying on board, too (if any, but likely so). Unlikely
> >> >HPGe, but then who knows, Mars is a cold place, they may
> >> >have figured some practical way to cool things down to
> >> >about liquid nitrogen.
>
> >> Well, they certainly don't have much atmospheric pressure to
> >> worry about.
>
> >> Which reminds me of another thing. How do they convect the
> >> internally generated heat away. I recall hearing about
> >> multiple power systems, operating around 32V at near 2A. More
> >> than one. This power must be convected/conducted away -- no
> >> way they want to radiate it. I wonder if they push it
> >> (costing more heat) towards a vane or arm and drag it around
> >> on the surface to get rid of it?
>
> >The atmosphere won't help much.
>
> >Why not?  Thermal conductivity of air is pretty much constant till you
> >get below 1 Torr or so.  Wiki says the mean pressure on mars is about
> >0.1 psi, which is ~5 torr.
>
> Good point.
>
> What triggered my comment is remembering that heat buildup
> was most certainly a problem during broadcasts with the high
> gain antenna system towards Earth. They can't operate it
> continuously, if I recall correctly. Made me wonder about the
> rest. I had also remembered the case of satellites and "knew"
> that the Martian atmosphere could be as little as a few tens
> of Pascals. So I projected that heat accumulation may be a
> problem. Apparently, it isn't.
>
> I gather your point. To understand it more fully, I need to
> think more closely about mean-free-path, I guess. Thanks.

There may be less convection on Mars.  I don't know how that changes
with pressure.
(But there must be some change, Someone makes 'convectron' thermal
couple gauges that give readings up to an atmosphere.  (760 Torr)
>
> >Re spectrometer calibration:  We had this "black body" source. (from
> >Ortec?)  That could be used for intensity calibration.  PITA though.
>
> The problem for students is that they cannot afford the $800
> it takes to get a $8 tungsten bulb calibrated. (It can cost a
> lot more than that, too.) Then they need to set up a careful
> station for making the calibration. It's just plain too
> expensive to do. And I don't know a way around it. Wavelength
> calibration is CHEAP!! $12 buys a merc-argon calibration
> lamp, which fires up with the Argon first (for about a minute
> or two where you get some very nice Argon lines in the longer
> wavelengths) and then the Mercury kicks in and dominates with
> it's lines. A couple of well-timed snapshots and you've got
> enough (with software) to completely calibrate your pixel
> positions in a cheap ($10) megapixel camera.
>
> I'd LOVE to figure out a cheap intensity calibration setup,
> though. So would a lot of other people, I suppose.
>
> >But maybe you could do something on the cheap with a tungsten light
> >bulb.
>
> But that's the problem. I can get a cheap tungsten lamp. They
> are VERY CHEAP. In fact, the EXACT SAME ONE I would buy,
> calibrated, is dirt cheap uncalibrated. It is the calibration
> data that comes with a newly calibrated lamp that costs so
> darned much. It needs to be traceable to standards. And you
> pay for that. Plus, you need an expensive power supply to
> operate it (0.1% current control is standard.) And it ages,
> too. Within 100 hours or so, it's drifted enough that it
> needs recalibration.

OK first a disclaimer, I know squat about the details of spectrometer
calibration.

It would seem to break down into two pieces.  Absolute sensitivity (at
one wavelength) and then relative wavelength sensitivity.

For the first part you could maybe do something with a laser diode
into photodiode and then the same laser (though a bunch of
attenuators) into the spectrometer.

For the second you have the students use the black body curve and the
tungsten lamp.  Operate the lamp at two different temperatures.
(Maybe build a nice stable DC supply for the lamp.)  It seems like you
should be able to extract an approximate sensitvity curve from two
black body curves, even if you don't know the exact temperatures.
(But I'll leave that as an excersise for the students :^)

How good a calibration do you need?

George H.
>
> Thanks,
> Jon- Hide quoted text -
>
> - Show quoted text -

On Aug 7, 7:57 pm, Jon Kirwan <j...@infinitefactors.org> wrote:
> On Wed, 08 Aug 2012 09:42:05 +1000, Adrian Jansen
>
>
>
>
>
> <adr...@qq.vv.net> wrote:
> >On 8/8/2012 7:04 AM, Jon Kirwan wrote:
>
> >>>> Which reminds me of another thing. How do they convect the
> >>>> internally generated heat away. I recall hearing about
> >>>> multiple power systems, operating around 32V at near 2A. More
> >>>> than one. This power must be convected/conducted away -- no
> >>>> way they want to radiate it. I wonder if they push it
> >>>> (costing more heat) towards a vane or arm and drag it around
> >>>> on the surface to get rid of it?
>
> >>> The atmosphere won't help much.
>
> >>> Why not?  Thermal conductivity of air is pretty much constant till you
> >>> get below 1 Torr or so.  Wiki says the mean pressure on mars is about
> >>> 0.1 psi, which is ~5 torr.
>
> >> Good point.
>
> >In earth atmosphere, I understand most heat above around 300K ( 'room'
> >temp ) is carried by radiation and convection.  Conduction is a minor part.
>
> >No idea what convection is like at 5 torr in a CO2 atmosphere, but I
> >suspect its a lot lower.
>
> Then that begs the question, again. Perhaps George spoke too
> soon.

Sure, I'm always putting my foot in my mouth!
(I must enjoy the taste of toe jam :^)

On Earth once the temp difference is above a few degrees I think
convection is the biggest source of heat transfer.  But I have no idea
of how that changes with pressure.  Maybe some day I can build a
convectron pressure gauge.  The patent on that must be expired.

George H.
>
> I'll go dig. I'm ignorant and don't like the feeling.
>
> Jon- Hide quoted text -
>
> - Show quoted text -

George Herold wrote:

> On Earth once the temp difference is above a few degrees I think
> convection is the biggest source of heat transfer.  But I have no idea
> of how that changes with pressure.  Maybe some day I can build a
> convectron pressure gauge.  The patent on that must be expired.

Convection flow requires gravity. Laptops on various space labs
starting with the skylab and Shuttle found out about this. For
convection to work it needs gravity so the lighter heated air
moves *up* being displaced by cooler heavier air. On Mars
no problem except the amount of heat the atmosphere can carry.

w..

Jon Kirwan schrieb:

> Of all those single points of failure, the ones that worried
> me the most were the pyros. You can test a lot of things --
> like the 65,000 pounds of force the parachute had to bear.
> But you can't test the ACTUAL pyros you will use. No matter
> what you do, the ones you place in there can't have been
> tested. We know how to make explosives of great uniformity,
> of course. But all of that has to go into a system and it
> must fire exactly correctly, under buffeting circumstances,
> without a single point of failure in a single pyro. Just one
> and that is it. Not that the rest wasn't also difficult. But
> some of the things, since as the novel use of an imbalance in
> weight distribution in order to permit direction control
> during entry, can have errors in one part of the software be
> compensated by the outer control loop in another part. So
> even there, there is a backup hope. But the pyros either
> work, or don't. That's what I was watching mostly for, though
> the rest was also sincerely knuckle-whitening as well.

Hello,

pyros have been used for more than five decades in space missions and 
they were critical for each mission. They were used for stage 
separation, four or more for each stage and all should work perfect.
But it is possible to test the cabling and the fuse of the pyro by 
measuring the resistance without blowing them. I guess there were more 
than twenty pyros necessary for this mission.
If hundred pyros were built within one lot, you may test fifty or more 
and use only the rest if all tests were perfect. You may even test some 
just before the start, if one fails all pyros of this type and lot have 
to be replaced. Not cheap, but a failing pyro is much more expensive.

Bye

Bye

On Tue, 07 Aug 2012 11:53:33 +0300, upsidedown@downunder.com wrote:

>On Tue, 07 Aug 2012 08:13:26 +1000, Jordan <jordan@koora.com> wrote:
>
>>
>>
>>> http://www.abc.net.au/news/2012-08-06/nasa-celebrates-successful-mars-landing/4180454
>>>
>>
>>Great achievement, but have we forgotten something?
>>I was surprised when I mentioned to some friends that there have been 
>>successful landings on Mars since at least 1976 - they were astonished 
>>and disbelieving.
>
>Apparently the first pictures from the surface of Mars were taken by
>Mars 3 in 1971, so successful landings happened a few years earlier.


Success is relative.  Mars 3 did indeed land on Mars in 1971, but
failed some 15 seconds after.  It transmitted a partial frame in that
time, but the image contains nothing recognizable.

Walter Banks schrieb:

> There was certainly lots of redundancy. One number that is still
> impressive was that with all of the redundancy NASA identified about
> 250 remaining single point possible failures. The math on that many
> series terms makes the comment understandable.

Hello,

redundancy is possible for small and critical parts, but there are also 
some large critical parts, the main rocket engines, the tanks, the heat 
shield. You may use three instead of one parachute, but does it work 
with only two of three parachutes?

Bye

Adrian Jansen <adrian@qq.vv.net> wrote in
news:5021A7CD.9010208@qq.vv.net: 

> 
> On 8/8/2012 7:04 AM, Jon Kirwan wrote:
> 
>>>>
>>>> Which reminds me of another thing. How do they convect the
>>>> internally generated heat away. I recall hearing about
>>>> multiple power systems, operating around 32V at near 2A. More
>>>> than one. This power must be convected/conducted away -- no
>>>> way they want to radiate it. I wonder if they push it
>>>> (costing more heat) towards a vane or arm and drag it around
>>>> on the surface to get rid of it?
>>>
>>> The atmosphere won't help much.
>>>
>>> Why not?  Thermal conductivity of air is pretty much constant till
>>> you get below 1 Torr or so.  Wiki says the mean pressure on mars is
>>> about 0.1 psi, which is ~5 torr.
>>
>> Good point.
>>
> 
> In earth atmosphere, I understand most heat above around 300K ( 'room'
> temp ) is carried by radiation and convection.  Conduction is a minor
> part. 
> 
> No idea what convection is like at 5 torr in a CO2 atmosphere, but I 
> suspect its a lot lower.
> 

FYI,Wikipedia has a great page on the Mars lander,and describes the thermal 
management very well.

It appears the problem is keeping everything in the lander warm,not getting 
rid of excess heat. the Radioisotope Thermal Generator provides both 
leectric power and extra heat,and there's a system of cooling tubes that 
can route heat to where it's needed or to take it away.

One neat factoid;
the tires have a tread pattern that spells out JPL in Morse,and the tread 
pattern left in the dirt is used to measure the distance travelled by the 
lander.

-- 
Jim Yanik
jyanik
at
localnet
dot com

Uwe Hercksen <hercksen@mew.uni-erlangen.de> wrote in 
news:a8f6c7Ffo3U1@mid.dfncis.de:

> 
> 
> Jon Kirwan schrieb:
> 
>> Of all those single points of failure, the ones that worried
>> me the most were the pyros. You can test a lot of things --
>> like the 65,000 pounds of force the parachute had to bear.
>> But you can't test the ACTUAL pyros you will use. No matter
>> what you do, the ones you place in there can't have been
>> tested. We know how to make explosives of great uniformity,
>> of course. But all of that has to go into a system and it
>> must fire exactly correctly, under buffeting circumstances,
>> without a single point of failure in a single pyro. Just one
>> and that is it. Not that the rest wasn't also difficult. But
>> some of the things, since as the novel use of an imbalance in
>> weight distribution in order to permit direction control
>> during entry, can have errors in one part of the software be
>> compensated by the outer control loop in another part. So
>> even there, there is a backup hope. But the pyros either
>> work, or don't. That's what I was watching mostly for, though
>> the rest was also sincerely knuckle-whitening as well.
> 
> Hello,
> 
> pyros have been used for more than five decades in space missions and 
> they were critical for each mission. They were used for stage 
> separation, four or more for each stage and all should work perfect.
> But it is possible to test the cabling and the fuse of the pyro by 
> measuring the resistance without blowing them. I guess there were more 
> than twenty pyros necessary for this mission.
> If hundred pyros were built within one lot, you may test fifty or more 
> and use only the rest if all tests were perfect. You may even test some 
> just before the start, if one fails all pyros of this type and lot have 
> to be replaced. Not cheap, but a failing pyro is much more expensive.
> 
> Bye
> 
> Bye
> 
> 

Heh,testing of the pyros reminds me of a "tech" at TEK-Indianapolis that 
had a scope in for repair that blew it's line fuse,and he went and got all 
the fuses from bench stock,and one by one,put them in and each time tried 
powering up the scope,never first finding where the excess load was,or 
using a Variac to bring up the power slowly and measuing the DC supplies.

Only after blowing ALL the fuses in stock of that value did he ask another 
tech what he should do....

He never did work out as a repair tech. He didn't want to learn.
But he was sure good at avoiding work.

-- 
Jim Yanik
jyanik
at
localnet
dot com

On 08/08/12 23:10, Robert Wessel wrote:

>
> Success is relative.  Mars 3 did indeed land on Mars in 1971, but
> failed some 15 seconds after.  It transmitted a partial frame in that
> time, but the image contains nothing recognizable.
>

So only 99% success then.

Jordan wrote:
> 
> On 08/08/12 23:10, Robert Wessel wrote:
> 
> >
> > Success is relative.  Mars 3 did indeed land on Mars in 1971, but
> > failed some 15 seconds after.  It transmitted a partial frame in that
> > time, but the image contains nothing recognizable.
> >
> 
> So only 99% success then.

I don't know that I've ever met a customer who would consider that a
success.  You work for local government, maybe? ;)

It definitely belongs in the category of heartbreaking near-misses,
though.

Cheers

Phil Hobbs

-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

Convection is the transfer of heat to and from a fluid.  This is true 
whether the fluid flows by change in density or by an external force, and 
includes diffusion, which occurs in space even when the laptop's fan is off.

The component of heat transfer due entirely to mass flow is called 
advection, and does not include diffusion.

Tim

-- 
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

"Walter Banks" <walter@bytecraft.com> wrote in message 
news:50225B5D.1F7B950C@bytecraft.com...
>
>
> George Herold wrote:
>
>> On Earth once the temp difference is above a few degrees I think
>> convection is the biggest source of heat transfer.  But I have no idea
>> of how that changes with pressure.  Maybe some day I can build a
>> convectron pressure gauge.  The patent on that must be expired.
>
> Convection flow requires gravity. Laptops on various space labs
> starting with the skylab and Shuttle found out about this. For
> convection to work it needs gravity so the lighter heated air
> moves *up* being displaced by cooler heavier air. On Mars
> no problem except the amount of heat the atmosphere can carry.
>
> w..
>
> 

Jim Yanik wrote:
> 
> Heh,testing of the pyros reminds me of a "tech" at TEK-Indianapolis that
> had a scope in for repair that blew it's line fuse,and he went and got all
> the fuses from bench stock,and one by one,put them in and each time tried
> powering up the scope,never first finding where the excess load was,or
> using a Variac to bring up the power slowly and measuing the DC supplies.
> 
> Only after blowing ALL the fuses in stock of that value did he ask another
> tech what he should do....
> 
> He never did work out as a repair tech. He didn't want to learn.
> But he was sure good at avoiding work.


   Was that Sloman or Maynard? ;-)

On Wed, 08 Aug 2012 17:33:29 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>Jordan wrote:
>> 
>> On 08/08/12 23:10, Robert Wessel wrote:
>> 
>> > Success is relative.  Mars 3 did indeed land on Mars in 1971, but
>> > failed some 15 seconds after.  It transmitted a partial frame in that
>> > time, but the image contains nothing recognizable.
>> 
>> So only 99% success then.
>
>I don't know that I've ever met a customer who would consider that a
>success. 

Well, it got 100% of the way there 8-)

Problem is - it may have been sitting there completely functional
except for it's transmitter(s).

George

On Wed, 08 Aug 2012 15:13:03 +0200, Uwe Hercksen
<hercksen@mew.uni-erlangen.de> wrote:

>
>
>Walter Banks schrieb:
>
>> There was certainly lots of redundancy. One number that is still
>> impressive was that with all of the redundancy NASA identified about
>> 250 remaining single point possible failures. The math on that many
>> series terms makes the comment understandable.
>
>Hello,
>
>redundancy is possible for small and critical parts, but there are also 
>some large critical parts, the main rocket engines, the tanks, the heat 
>shield. You may use three instead of one parachute, but does it work 
>with only two of three parachutes?
>
>Bye

In the instances i have been privileged to look at two of three works as
some acceptable damage risk, one of three generally includes serious
damage risk usually considered casualty mode case (barely walking
wounded).

?-)