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MSL EDL Hardware, Its state & fate
bigdipper
post Aug 7 2012, 06:17 PM
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Looking at the HiRISE imagery of the descent stage, does the distribution of the debris field represent the disintegration of the stage from impact only, or is it possible that some or all of the 140+/- kilos of Hydrozine exploded and expanded the debris field? [I understand the darker albedo material is from below the surface]

Does the thin martian atmosphere contain enough oxygen to support combustion/explosion? [guessing No, but my chem is insufficient]

Were the hydrazine cells sufficiently designed to survive impact intact?

I couldn't find anything on the net or in the specs, any ideas?
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ugordan
post Aug 7 2012, 06:24 PM
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QUOTE (bigdipper @ Aug 7 2012, 08:17 PM) *
Does the thin martian atmosphere contain enough oxygen to support combustion/explosion? [guessing No, but my chem is insufficient]

No, but monopropellant hydrazine in the tanks is its own fuel and oxidizer.


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Drkskywxlt
post Aug 7 2012, 06:25 PM
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QUOTE (Doc @ Aug 7 2012, 02:09 PM) *
But surely they'd be too small.


Each ballast weighed 55lb, so those should make a decent dent in the surface.

Suspicious smudges highlighted:
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Pando
post Aug 7 2012, 06:33 PM
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QUOTE (fredk @ Aug 7 2012, 10:15 AM) *
From hirise I measure an azimuth of -71 deg for the DS impact. IF the rhaz is pointing exactly along the rover axis, then the centre of the rhaz frames should be at -66 (using rover azimuth 114 deg). But the cloud is left of centre frame. So using the above scale, I get the cloud to be between az -72 and -80 degrees. So a bit off. But the assumption of rhaz on axis could easily be out by a few degrees.


The dust cloud could have drifted somewhat since the crash. Looking at the crests of those black dunes, it appears that the prevailing winds are roughly north to south. If we're looking at west-northwest with the rear hazcam, I find it plausible that some drifting toward the left may have occurred due to wind.

Since we now have the direction roughly correct, it all depends on the exact timing of the images to really nail it down.
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dvandorn
post Aug 7 2012, 06:34 PM
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The image of the descent stage impact site(s) is really, really interesting. First off, while everything sprays down in the direction of travel, there are very specific plumes angling off about 50 to 60 degrees on either side of the main motion vector. Looks a lot like the angle at which the opposite-side engine pods are mounted from one another.

Could the descent stage have hit the ground with engines running and flipped over, spraying a blast of exhaust ahead of it and along the angles consistent with their attachment to the frame of the stage? And then after hitting ground following the first flip, disintegrated and resulted in the long tongue of disturbance from the initial impact point to the final impact point?

Just random thoughts...

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Greenish
post Aug 7 2012, 06:34 PM
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QUOTE (fredk @ Aug 7 2012, 02:15 PM) *
Bigger than that - at 0.12 deg/px and 650 m distance I get 1.36 m/px, so the cloud is roughly 70 or 80 m across/high.

From hirise I measure an azimuth of -71 deg for the DS impact. IF the rhaz is pointing exactly along the rover axis, then the centre of the rhaz frames should be at -66 (using rover azimuth 114 deg). But the cloud is left of centre frame. So using the above scale, I get the cloud to be between az -72 and -80 degrees. So a bit off. But the assumption of rhaz on axis could easily be out by a few degrees.

In fact, I'm way more willing to accept a few degree offset than a DD that magically appeared as we landed!

edit: that scale refers to the full res (1024 pix wide) image.


I was referring to the disturbed zone around the rover created by the descent stage hover as seen in HiRise image. Sorry if I was not clear; original post clarified.
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Doc
post Aug 7 2012, 06:38 PM
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QUOTE (Drkskywxlt @ Aug 7 2012, 09:25 PM) *
Each ballast weighed 55lb, so those should make a decent dent in the surface.


I don't know... unsure.gif

Here is a cropped up view.
Attached Image


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kwan3217
post Aug 7 2012, 06:38 PM
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QUOTE (Drkskywxlt @ Aug 7 2012, 11:25 AM) *
Each ballast weighed 55lb, so those should make a decent dent in the surface.

Suspicious smudges highlighted:

Google Mars had pre-landing hirise data yestetday, see if the spots are there then.
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Tesheiner
post Aug 7 2012, 06:40 PM
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QUOTE (Drkskywxlt @ Aug 7 2012, 08:25 PM) *
Each ballast weighed 55lb, so those should make a decent dent in the surface.

Suspicious smudges highlighted:

Too close to the landing site. Remember that the ballasts were ejected way before the heatshield and the latter is further away than the smudges. Those seem to be shadows of the terrain (see image from GE).
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ugordan
post Aug 7 2012, 06:41 PM
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QUOTE (kwan3217 @ Aug 7 2012, 08:38 PM) *
see if the spots are there then.

They are, that's terrain shadows.

Don't use screencaps off of NASA TV of HiRISE images reduced in resolution to hunt for ballast impacts. They are probably further downrange than the heatshield, anyway.


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Drkskywxlt
post Aug 7 2012, 06:42 PM
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QUOTE (Doc @ Aug 7 2012, 02:38 PM) *
I don't know... unsure.gif


Hmmm...bottom/southern two look like shadows in that version. Top/northern ones I'm not sure.

Edit: Shadows it is!
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Skyrunner
post Aug 7 2012, 06:43 PM
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QUOTE (Drkskywxlt @ Aug 7 2012, 08:25 PM) *
Each ballast weighed 55lb, so those should make a decent dent in the surface.

Suspicious smudges highlighted:


Placed the larger tiff of the boxed section in the image...those smudges don't look like craters, more like small mounds. Shouldn't the 'ballast-crateters' be located more downrange?
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kwan3217
post Aug 7 2012, 06:43 PM
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QUOTE (ugordan @ Aug 7 2012, 11:24 AM) *
No, but monopropellant hydrazine in the tanks is its own fuel and oxidizer.

Strictly speaking, monoprop doesn't even burn, it decomposes. In an engine, it is triggered by a metal catalyst. Is iron oxide an appropriate catalyst? If so, then I can see the tanks splitting on impact then the fuel igniting when it hits the dust.
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Explorer1
post Aug 7 2012, 06:57 PM
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When it comes to finding the ballast impacts, remember that Oppy found a bunch of meteorites, and purely by chance. In the coming months/years MSl will doubtless be traveling a long way, and in the direction of Mt. Sharp to boot. If they are found; I won't be surprised.
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Skyrunner
post Aug 7 2012, 07:05 PM
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QUOTE (kwan3217 @ Aug 7 2012, 08:43 PM) *
In an engine, it is triggered by a metal catalyst. Is iron oxide an appropriate catalyst?

No, from my bare head you need a catalyst with iridium and/or ruthenium normally. Metals like cobalt, nickel or iron will speed up the decomposition but not nearly to the point of catalytic decomposition (only 10x to max 100 x compared to air). The catch here is that this gets highly uncertain when CO2, H20 or CH4 is present.... guess what's in the atmosphere of Mars;-) There is a similar issue with acidic stuff pressent.


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Error: Life.sys corrupted
( R )eflect, ( R )epend, or ( R )eboot?
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