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Viking 1 & 2 landers from HiRISE, Landers definitively spotted
vikingmars
post Dec 6 2006, 03:52 PM
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smile.gif ...And the discovery of the location of the backshell and its parachute solves also a 30-year mistery : the darkening during a few seconds of the landing site as seen as a dark band in the 1st picture taken by VL1.
The very 1st lines at left of the image are light gray due to the moving dust raised by the engines (seen also on the 1st VL2 image) and then comes a much darker band. We were some people thinking that this darkening was made by the parachute that went in front of the Sun during its final descent. Because we were unable to see the backshell from the lander, we supposed that it was very close to the lander but hidden by one of the two nearest craters. Well this is the case !
Here are the 2 first images taken by VL1 showing the crater hidding the backshell and its now probable final landing trajectory (arrow). biggrin.gif
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Guest_AlexBlackwell_*
post Dec 6 2006, 04:44 PM
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Several years ago, I remember perusing a coffee table-type book on space exploration, and I noticed a high-resolution Viking orbiter picture of the VL1 landing site juxtaposed with an illustration depicting the VL1 aeroshell impacting the Martian surface. The caption accompanying both figures read:

QUOTE
Viking 1's sterilized protective aeroshell (left) gouged out a small crater, half a mile (750 metres) north of the lander site itself (small arrow). The crater (large arrow) was not discovered until orbiter pictures were analysed in 1987.


Unfortunately, the book didn't offer any references for the picture; however, four years ago I contacted Bob Craddock at NASM. Years earlier, he had submitted an abstract to the 1994 Mars Environmental Survey workshop entitled "Rationale for a Mars Pathfinder Mission to Chryse Planitia (20 Degrees N, 40 Degrees W) and the Viking 1 Lander." His abstract suggested that MPF could examine the hole gouged out by the VL1 aeroshell, and I thought he might be able to track down the reference I was looking for.

Craddock replied:

QUOTE
Unfortunately the reference you are looking for as never been published in a peer-reviewed journal. While still at NASA Goddard, Jim Garvin together with Olivier de Goursac from France's Promospace determined what would have been the most likely trajectory for the Viking aeroshell. They then examined photographs of the landing area taken after the spacecraft was on the surface and suggested that a small depression may have been created by the aeroshell. All of this came out in a half-page article in Aviation Week and Space Technology published on June 22, 1987, pages 84-85. The article does not reference an author. I asked Jim as to how the article got published, but that was years ago and I can't remember the story now.


I contacted Garvin at about the same time (ca. 2002), and he replied "I will look into it. I did that work with Olivier for fun, and it was 'published' in a magazine, not a peer-reviewed journal. It's been a while and my files are buried in deep vault storage at GSFC. Let me see what I can dig up!"

I just realized that I never followed-up with him biggrin.gif
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tim53
post Dec 6 2006, 06:30 PM
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QUOTE (vikingmars @ Dec 6 2006, 07:52 AM) *
smile.gif ...And the discovery of the location of the backshell and its parachute solves also a 30-year mistery : the darkening during a few seconds of the landing site as seen as a dark band in the 1st picture taken by VL1.
The very 1st lines at left of the image are light gray due to the moving dust raised by the engines (seen also on the 1st VL2 image) and then comes a much darker band. We were some people thinking that this darkening was made by the parachute that went in front of the Sun during its final descent. Because we were unable to see the backshell from the lander, we supposed that it was very close to the lander but hidden by one of the two nearest craters. Well this is the case !
Here are the 2 first images taken by VL1 showing the crater hidding the backshell and its now probable final landing trajectory (arrow). biggrin.gif


The backshell and parachute most likely impacted the surface before the lander touched down. Even without the weight of the lander, in the thin Martian atmosphere, the backshell and parachute (still inflated since they didn't use RAD rockets to slow the descent) would have been traveling at about 100mph.

-Tim.
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tim53
post Dec 6 2006, 06:31 PM
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I remember that Aviation Week article. Simply put, they misidentified features on the ground and noise in the images as hardware.

-Tim.

QUOTE (AlexBlackwell @ Dec 6 2006, 08:44 AM) *
Several years ago, I remember perusing a coffee table-type book on space exploration, and I noticed a high-resolution Viking orbiter picture of the VL1 landing site juxtaposed with an illustration depicting the VL1 aeroshell impacting the Martian surface. The caption accompanying both figures read:

[/indent]

Unfortunately, the book didn't offer any references for the picture; however, four years ago I contacted Bob Craddock at NASM. Years earlier, he had submitted an abstract to the 1994 Mars Environmental Survey workshop entitled "Rationale for a Mars Pathfinder Mission to Chryse Planitia (20 Degrees N, 40 Degrees W) and the Viking 1 Lander." His abstract suggested that MPF could examine the hole gouged out by the VL1 aeroshell, and I thought he might be able to track down the reference I was looking for.

Craddock replied:

[indent]


I contacted Garvin at about the same time (ca. 2002), and he replied "I will look into it. I did that work with Olivier for fun, and it was 'published' in a magazine, not a peer-reviewed journal. It's been a while and my files are buried in deep vault storage at GSFC. Let me see what I can dig up!"

I just realized that I never followed-up with him biggrin.gif
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Ant103
post Dec 6 2006, 06:48 PM
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[out_of-subjectmode]Oh? Olivier, qu'est-ce que tu deviens? On te vois pas beacoup ces temps-ci biggrin.gif[/out__subjectmode]

The shadow of the parachute? I was thinking that it was CCD lines those are due to the very beginning of the camera activity huh.gif ... It's very linear...


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Guest_AlexBlackwell_*
post Dec 6 2006, 06:50 PM
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QUOTE (tim53 @ Dec 6 2006, 08:31 AM) *
I remember that Aviation Week article. Simply put, they misidentified features on the ground and noise in the images as hardware.

What I didn't post was a comment from another, prominent Mars scientist when I asked him about this whole issue: "It's was a bunch of nonsense."
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tim53
post Dec 6 2006, 07:06 PM
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QUOTE (AlexBlackwell @ Dec 6 2006, 10:50 AM) *
What I didn't post was a comment from another, prominent Mars scientist when I asked him about this whole issue: "It's was a bunch of nonsense."


I bet I can guess who that was! biggrin.gif
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tim53
post Dec 6 2006, 07:18 PM
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QUOTE (Ant103 @ Dec 6 2006, 10:48 AM) *
[out_of-subjectmode]Oh? Olivier, qu'est-ce que tu deviens? On te vois pas beacoup ces temps-ci biggrin.gif[/out__subjectmode]

The shadow of the parachute? I was thinking that it was CCD lines those are due to the very beginning of the camera activity huh.gif ... It's very linear...


The Viking lander cameras didn't use CCDs, but photodiodes whereby an image was slowly built up by tilting a tiny mirror up and down and rotating the whole camera body in azimuth to add "pixels" to the scene. The vertical bands are due to lighting changing as the scene was acquired, due to dust from the landing settling over the several minutes it took to take the picture.

The parachute would have settled onto the surface in a fraction of a second after the backshell landed. There might have been dust kicked up, but it's affect on the lander is probably much less than that of the lander's descent engines locally.

-Tim.
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Guest_AlexBlackwell_*
post Dec 6 2006, 07:21 PM
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QUOTE (tim53 @ Dec 6 2006, 09:06 AM) *
I bet I can guess who that was! biggrin.gif

I'm sure you could, Tim. As I gather it, that's one of his favorite phrases cool.gif
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vikingmars
post Dec 6 2006, 07:37 PM
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[quote name='Ant103' date='Dec 6 2006, 07:48 PM' post='76994']
[out_of-subjectmode]Oh? Olivier, qu'est-ce que tu deviens? On te vois pas beacoup ces temps-ci biggrin.gif[/out__subjectmode]

Merci Ant103.
En fait, j'ai subi une série de décès familiaux ces 10 dermiers mois, dont mon épouse mi-septembre. Me voici veuf à 47 ans avec 5 enfants... Et puis je travaille beaucoup en ce moment sur des sujets lune sur demande de copains outre-atlantique pour vendre leur nouveau programme...
Bien amicalement,
Olivier
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vikingmars
post Dec 6 2006, 08:20 PM
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smile.gif OK, here is the article from AWST ! The "discovery" was a by-product from a scientific paper Jim and I presented at the DPS meeting in Houston about the erosional rates measured on the VL1 site. We had only the 7-m resolution pics from orbit and this "V" feature (maybe it will prove to be just some rocks, despite its darkness almost disappeared in the most recent MOC images) was obviously for us a fresh impact crater. And a good proof that the immediate underlying soil layers at the VL1 site -even away from the immediate vicinity of the lander- were much darker than the upper layers (see the darkening of the surface after a dust storm sol 1742 dust storm which revealed those dark layers from place to place)
My apologizes to those wo think that it is "a bunch of nonsense"... huh.gif
Anyway, we had great fun processing the Orbiter images, pixel-overlaping them together to gain more details !
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Guest_AlexBlackwell_*
post Dec 6 2006, 08:26 PM
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QUOTE (vikingmars @ Dec 6 2006, 10:20 AM) *
My apologizes to those wo think that it is "a bunch of nonsense"... huh.gif
Anyway, we had great fun processing the Orbiter images, pixel-overlaping them together to gain more details !

Thanks, Olivier. At least now I don't have to bug Jim Garvin to go through his archived files, unless, of course, his files are in such disarray that he's still searching four years later. biggrin.gif

EDIT: And as for the "nonsense" comment, which I thought a bit extreme, that was from a famous curmudgeon cool.gif

Thanks again.

This post has been edited by AlexBlackwell: Dec 6 2006, 08:40 PM
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climber
post Dec 6 2006, 08:54 PM
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quote name='Ant103' date='Dec 6 2006, 07:48 PM' post='76994']
[out_of-subjectmode]Oh? Olivier, qu'est-ce que tu deviens? On te vois pas beacoup ces temps-ci [/out__subjectmode]

Merci Ant103.
En fait, j'ai subi une série de décès familiaux ces 10 dermiers mois, dont mon épouse mi-septembre. Me voici veuf à 47 ans avec 5 enfants... Et puis je travaille beaucoup en ce moment sur des sujets lune sur demande de copains outre-atlantique pour vendre leur nouveau programme...
Bien amicalement,
Olivier


J'imagine que vous parlez de ceci :
http://www.unmannedspaceflight.com/index.p...amp;#entry77018

J'en suis encore secoué, mille bravo(s)


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tim53
post Dec 6 2006, 09:11 PM
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QUOTE (AlexBlackwell @ Dec 6 2006, 12:26 PM) *
Thanks, Olivier. At least now I don't have to bug Jim Garvin to go through his archived files, unless, of course, his files are in such disarray that he's still searching four years later. biggrin.gif

EDIT: And as for the "nonsense" comment, which I thought a bit extreme, that was from a famous curmudgeon cool.gif

Thanks again.


Most definitely I know of whom you refer.

...I make misidentifications all the time... (so does the curmudgeon)

...well, hopefully not ALL the time!

But the point is that, in this business, or any other scientific exploration business, we put forth our hypotheses, test them, and if necessary toss them out or revise them based on new information.

That's how it works.

-Tim
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vikingmars
post Dec 6 2006, 09:12 PM
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Oui, Climber !
Merci et ça m'a fait très plaisir (et une agréable surprise) de vous rencontrer à TSE...
La toute "première" des images a eu lieu en fait voici 15 jours à l'Adler Planetarium de Chicago devant des centaines d'auditeurs. Elles étaient présentées officiellement par la Nasa/Hq avec Buzz Aldrin, Gene Cernan et Jim Lovell... D'autres présentations auront lieu aux US prochainement, mais je n'en ai pas le calendrier... Je suis "off" pour Mars tellement le boulot est énorme... Ce travail a été entamé dès 1984 à Brown University pour le repérage des images. Les premiers tests d'assemblage ont eu lieu en 1998, les validations des corrections chromatiques en 2001... Puis j'ai eu ma "parenthèse" MER pour aider à monter l'Outreach en prévision du succès que vous connaissez.
Bon, il faut que je reparte sur la Lune...
Amitiés,
Olivier.
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