TEGA - Round 2 |
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TEGA - Round 2 |
 Aug 15 2008, 06:56 AM
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#166
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 Senior Member  Group: Admin Posts: 3108 Joined: 21-December 05 From: Canberra, Australia Member No.: 615  |
Similar door opening to the very first oven.
Astro0 |
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Aug 15 2008, 08:31 AM
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#167
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 Member Group: Members Posts: 144 Joined: 17-July 07 From: Canberra Australia Member No.: 2865 |
Given that they are trying for an ice sample, and the difficulties previously experienced with this, why the heck are they opening a door on the 'poor performance' side of the TEGA. Logic would seem to dicatate that you go with the successful side to preclude the possibility of (for instance) the arm throwing the claw in and precluding further samples.
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Aug 15 2008, 08:38 AM
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#168
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Member Group: Members Posts: 470 Joined: 24-March 04 From: Finland Member No.: 63 |
Apparently it isn't for an ice sample. This is a comment from Ray in Emily's blog:
QUOTE The goal at Burn Alive is to get a sample from an intermediate depth, a couple centimeters above the ice-soil interface.
-------------------- Antti Kuosmanen
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Aug 15 2008, 09:53 AM
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#169
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Member Group: Admin Posts: 468 Joined: 11-February 04 From: USA Member No.: 21 |
SSI color of TEGA from sol 79
 Also, here's a color blink showing the open doors vs. an unopened background: sol 79 - sol 61 |
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 Aug 15 2008, 10:22 AM
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#170
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 Junior Member Group: Members Posts: 36 Joined: 7-November 05 Member No.: 546 |
Here,
http://www.nasa.gov/mission_pages/phoenix/...s/AFM-rev3.html NASA "chemists" inform the public that, if perchlorate were present, TEGA should probably see chlorine gas. That is a mistake. Perchlorate desintegrates in several steps to chloride, for example potassium or sodium chloride (KCl or NaCl) which will not give alkali metal and chlorine at all - not at 1000 degree C. For the same reason, a solid fuel booster does not produce a greenish smoke streak. Interestingly, in a chloride rich layer with trace amounts of oxygen (mayby especial atomic oxygen as a result of photo dissociation of water) perchlorat is the most stable species and develops from hypochlorite (ClO-) or chlorite (ClO2-) via chlorate (ClO3-) by disproportionation. (foprmig the next higher "chloride-oxide" and chloride. The motor for this the tetrahedonal structur and the energetical metastable state of the perchlorat as a result of chemical bonds given to all eight chloride-electrons. Another possibility would be peroxo-disulphate as a relatively stable species of the layer is sulphate rich; nitrates are more difficult, because there is only one stable anorganic nitrogen rich starting material: ammonia (NH4+), mayby in form of ammonia carbonate or -carbamate. |
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Aug 19 2008, 07:59 AM
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#171
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 Junior Member Group: Members Posts: 44 Joined: 25-February 08 From: Greece, Komotini Member No.: 4055 |
Have they aquired a soil sample for TEGA oven 7? How many watts has Phoenix available right now and how many it needs just to stay alive (in hibernation mode)?
Attached thumbnail(s)
-------------------- "It`s one small step for a man. A giant leap for all mankind!" Armstrong, Apollo 11, 1969.
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Aug 19 2008, 10:56 AM
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#172
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 Senior Member Group: Members Posts: 1465 Joined: 9-February 04 From: Columbus OH USA Member No.: 13 |
QUOTE (Harkeppler @ Aug 15 2008, 06:22 AM)  Perchlorate desintegrates in several steps to chloride, for example potassium or sodium chloride (KCl or NaCl) which will not give alkali metal and chlorine at all - not at 1000 degree C. For the same reason, a solid fuel booster does not produce a greenish smoke streak. Interestingly, in a chloride rich layer with trace amounts of oxygen (mayby especial atomic oxygen as a result of photo dissociation of water) perchlorat is the most stable species and develops from hypochlorite (ClO-) or chlorite (ClO2-) via chlorate (ClO3-) by disproportionation. Thanks for the chemistry insight--so the results so far may be consistent after all. Here's a reference to natural formation of perchlorate from cloride: QUOTE PHOTOOXIDATION OF CHLORIDE TO PERCHLORATE IN THE PRESENCE OF TITANIUM DIOXIDE AND DESERT SOILS Perchlorate has been observed in playa soils in areas of the western United States, in nitrate deposits from northern Chile, and has also been observed at low concentrations in surface and groundwater in the southwestern United States, distant from industrial sources. Studies were conducted to determine if perchlorate could be formed when dry chloride salts were exposed to ultraviolet light (sunlight or ultraviolet lamps) in the presence of titanium dioxide and soils. Production of perchlorate was observed, and varied with the conditions used; for example, 59 days of UV-B irradiation of 8 mg of chloride in the presence of 200 mg of titanium dioxide on a petri dish resulted in the production of 260 ng/plate of perchlorate. In the presence of thin layers (ca. 3 mm) of desert soil collected from Death Valley, Calif. and exposed to sunlight for 3 months, perchlorate was observed at concentrations up to 45 ng/gm. Additionally, a limited number of desert soils were analyzed by ion chromatography to determine if perchlorate was present. Concentrations varied from non-detectable to 63 ng/gm of soil. Because titanium dioxide, and to a lesser extent, desert soils, have previously been shown to generate hydroxyl radical under irradiation, these results suggest a natural source of perchlorate in the arid regions of the southwestern United States. Also this: QUOTE Formation of natural perchlorate under strongly oxidizing conditions is possible through evaporation and production of ozone during electrical storms. These processes occur in northern New Mexico and may generate low concentrations of perchlorate during early stages of the hydrological cycle. -------------------- |
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Aug 20 2008, 07:50 AM
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#173
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Junior Member Group: Members Posts: 44 Joined: 25-February 08 From: Greece, Komotini Member No.: 4055 |
Doug, you told me the ceramic blank is on the deck, but I can`t find in the photos! can you show me a photo in which I can clearly see it (please make a circle around it, so I can see exactly where it is). What do you mean when you say "they will have to get it with the rasp". The rasp is needed to work the ceramic blank? Another think I`d like to learn is how many watts has Phoenix available right now and how many it needs just to stay alive (in hibernation mode)? (Sorry for my innumerous questions!!!).
-------------------- "It`s one small step for a man. A giant leap for all mankind!" Armstrong, Apollo 11, 1969.
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Aug 20 2008, 08:08 AM
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#174
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 Senior Member Group: Moderator Posts: 2262 Joined: 9-February 04 From: Melbourne - Oz Member No.: 16 |
We talked about the ceramic blank here, with close up photo
On the deck it is the white block that is in the area where the arm was stowed (and was therefore under the bio-barrier). About halfway between the camera and TEGA. EDIT:
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Aug 20 2008, 08:25 AM
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#175
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Junior Member Group: Members Posts: 44 Joined: 25-February 08 From: Greece, Komotini Member No.: 4055 |
Thank you very much my friend! but why Doug told me they`ll have to use the rasp to work? I think the ceramic blank should be on the TEGA, why it isn`t? can it work being away?
Attached image(s)
-------------------- "It`s one small step for a man. A giant leap for all mankind!" Armstrong, Apollo 11, 1969.
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Aug 20 2008, 08:55 AM
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#176
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 Member Group: Members Posts: 221 Joined: 25-March 05 Member No.: 217 |
It had to be under the bio-barrier with the RA to protect it from contamination until after landing (the TEGA ovens are sealed anyway) and the block is hard and has to be rasped to get the right sized particles and perhaps to clean the rasp and get to uncontaminated ceramic inside.
This is just off the top of my head it's awhile since I read about the ceramic block, hope this is of some help Roy |
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Aug 20 2008, 01:10 PM
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#177
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 Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
QUOTE (Ipparchus @ Aug 20 2008, 04:25 AM) I think the ceramic blank should be on the TEGA, why it isn`t? can it work being away? The ceramic blank works like this: A sample is collected from it just as a sample would be collected from the Martian surface and then transported by the scoop to TEGA and analyzed. So just as they might use the rasp to scrape up samples of ice for testing, they would use the rasp to scrape up a sample from the ceramic block. Just as the scoop dumps the ice sample into TEGA, it would dump the scraped up blank sample into TEGA. The entire ceramic block is not analysed as the blank, just the small sample that is scraped from it. |
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Aug 20 2008, 01:30 PM
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#178
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Rover Driver Group: Members Posts: 1015 Joined: 4-March 04 Member No.: 47 |
so how do they prevent contamination from soil left in the scoop?
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Aug 20 2008, 01:57 PM
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#179
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Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
QUOTE (remcook @ Aug 20 2008, 08:30 AM) so how do they prevent contamination from soil left in the scoop? I guess if they see a 99% drop in organic signal, the remaining 1% might be attributable to residue in the scoop. But larger signals would not be. There is also the issue of contamination by Martian dust settled on the surface of the blank. I think that the main purpose of the blank is not to check for contamination at all. The main purpose is to provide a controlled, organics free sample to ensure that TEGA does not signal the presence of organics when there are none present. It's mainly an instrument check, not a contamination check. IMO Although I would think that not detecting organics in the surface samples would provide the same control. |
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Aug 21 2008, 09:03 AM
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#180
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 Member Group: Members Posts: 568 Joined: 20-April 05 From: Silesia Member No.: 299 |
Delivery of sample to TEGA oven #7 (successful or not).
Attached thumbnail(s)
-------------------- Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html |
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