The hubbub merely had to do with the notion of presenting science info with the White House and not also releasing it publicly. That's it. Many people will take many things from that, and voila... bona fide brouhaha.

Speaking for myself, it was an exciting story. But I'm glad the truth is coming out now and we can get back to learning about Mars.

I find this all very interesting.... at what location and depth were the two MECA samples taken? It may be that the TEGA sample was deeper and something deeper down neutralizes the perchlorates.

A major goal of this mission is to characterize the differences in the soil chemistries as different layers are sampled.
This is really cool.

Too bad the science has to be worked under a carnival atmosphere. But then these missions and the science attract that.

Kudos to the Phoenix team for holding up with dignity under what has to be intense pressure all around.

And I just love this forum... you folks are great!!!

Craig

I think it is fun to engage in speculations - it forces you to engage in what the science is about. It is silly to pick a horse in what is not a horserace (I had "4", "-1" came in - so I guess I'm back to "3") so I'm bummed a bit. Guess it's like hoping the acceleration at the earth's surface was 30 ft/sec/sec and getting depressed 'cause it's 32. Aussie, Doug, nprev and others called it!

I think all the White House business was needlessly provocative. I'm glad the Phoenix team stepped up and told us what was going on.

Was perchlorate used as an oxidizer in the Delta II rocket motors that launched Phoenix? I.e., what are the chances of contamination?

It isn't necessary for a science team to get their story straight before publishing papers in peer-reviewed journals. In fact, it is quite common for authors to speculate on the wide range of possibilities presented by the data. For example, in a paper that I recently read on extrasolar planets, the authors described their observations, and then went on to speculate (educated guesses based on the observed phenomena) as to whether the planet has an intrinsic or induced magnetic field (or perhaps none at all!) in order to explain the data. After 16 pages, they essentially said they weren't sure what the heck was going on and needed more data...

Nope; no perchlorate propellants on the Delta II as far as I can tell from Google searching.

Stu, you've got the wrong end of the stick here. The whole point of what has happened here is that the science isn't done yet - that's why they didn't say anything Thursday. They want confirmation from TEGA. As far as I can tell, they have no relevant new results since Thursday, and today's press release was only done to quell the rumours.

Today's release was not an announcement that perchlorates have been found on Mars!

I sympathize with the science team here. There's no need for their process to be put under such scrutiny, though perhaps it's not surprizing in the internet age and given the public's interest in the L word. Science does not always move straight forward, even if it may appear that way when results are coming in fast, like in the early days of the mission. Science often veers left or right, screeches to a halt, breaks down and sits still for several weeks, starts backing up, before finally turning around and slowly making progress, if it's lucky. (Sounds a bit like Oppy trying to drive in Victoria crater!)

Just found this, from the launch press kit:

Phoenix was sealed up very tight during the launch, and for several months thereafter. I think the chances of perchlorate contamination are very, very slim.

Aha! You did a mo' better search then me!

Hell, sure, for all we know. The only stage that could have conceivably contaminated Phoenix would have been the 3rd, and hopefully they're considering the possibility.

The thruster "plates" are exposed through the aeroshell and there is a bevelled edge to them, I guess so they don't hang up when the lander is released. I wonder if there has to be even a small gap there. But then the Delta exhaust would have to work its way up the rocket and through the fairing seals. And then once you're moving, the early part of the slipstream should keep that at bay. I think the solids are jettisoned within the sensible part of the atmosphere.

But the Star 48 is used post-main stack separation, and physically closest to the vehicle itself. I think it's sensible to consider the possibility of contamination. Not saying that it's likely, just saying that it is possible.

They're definitely considering it, per Emily L's blog:



Just wondering what the potential source is.

I just read the press kit and the solids were kicked off well within the atmosphere, before fairing jett.

So the idea is that any stray perchlorate would be driven away by the air?

How about contamination beforehand--like when the spacecraft was mated to the third stage:




Or maybe the stage isn't even fueled at that point?

EDIT: Are you sure about the launch sequence? Here's a frame from the launch animation that seems to show the fairing coming off while the 3rd stage is still burning, and apparently above the atmosphere:

The stage is fueled at this point, and while I still think contamination from the propellant is only a remote possibility, if it did happen, then it probably happened here. Not at this exact moment, but at some point while the spacecraft and third stage were being processed in close proximity.

Please note too that very little, if any, perchlorate gets out of rocket exhaust intact.

Okay I'm an idiot - I was thinking about the Delta Solids not the PAM.

Well now it is interesting: there has to be a tiny bit of the plume that goes >backwards< in vacuum so perhaps the thruster plate "gaps" (if there are any - I don't know how you seal perfectly something that separates like it seems to) could be the culprit?

Isn't the solid fuel bound into the case at the factory, then cleaned and sealed?


But it doesn't burn perfectly and towards the end of the burn I wonder how ragged it gets through the grain.

EDIT: but it is a long daisy chain of improbables to get the bits that get out, then that tiny fraction that goes backwards, then sneaks through a gap (if there are any)...

Below is a very relevant excerpt from the Viking Lander 1 mission in August of 1976. This is all documented in the NASA SP-4212 "On Mars" and I would highly recommend it regarding all the clammer lately:

Data returned by the pyrolytic-release experiment and reported by Norman Horowitz on 7 August were equally confounding. Once again, the specialists had detected a reaction, but they did not know what it meant. "There's a possibility that this is biological," Horowitz said, but "there are many other possibilities that have to be excluded." The results obtained the night before were interesting but he emphasized that they were not ready to say that they had discovered life on Mars. "The data point we have is conceivably of biological origin, but the biological explanation is only one of a number of alternative explanations." He told the press: We hope by the end of this mission to have excluded all but one of the explanations, whichever that may be. I want to emphasize that if this were normal science, we wouldn't even be here-we'd be working in our laboratories for three more months-you wouldn't even know what was going on and at the end of that time we would come out and tell you the answer. Having to work in a fishbowl like this is an experience that none of us is used to.

He also cautioned the reporters that they were being included in the analysis phase of the experiments. They were "looking over the shoulder of a group of people who are trying to work in a normal way in an abnormal environment." The scientist's caution was prompted by his knowledge that "we well might be wrong in anything we say. Anyone who has carried out a scientific investigation knows that the pathway of science is paved not only with brilliant insights and great discoveries, but also with false leads and bitter disappointments. And nobody wanted to be wrong in public on a question as important as that of life on Mars."

Perchance a person somewhat unfamiliar with chemistry, but still cognizant of the plentiful chlorides in the Martian soil revealed by the wonderful rover teams, and also aware of plentiful energetic UV on the Martian surface, might ponder some interesting chemistry and innocently characterize the results as a 'chlorine analog to ozone', but it does sorta, kinda look like that is pretty much what might be going on with the perchlorate.

Yeah, maybe 'some' perchlorate tagged along from the Star 48, but we have UV and chemy precursors in abundance, so do we give a nod to the plausibility of perchlorates naturally occurring on Mars?

How hard would it be to dust off the old Viking surface chemistry experiment and dump some perchlorate in it and 'see what happens' ??

Great quote! But I think we all get the caveats and don't hold it against any of the science team. It's a privilege to get to watch them work (and a privilege (hard earned I'm sure) for them to work on our nation's space program).

EDIT: tasp got in my way

You're right, but at some point you have to put in the igniter, and I'm not sure exactly when this is. Also, some surface contamination is a remote possibility if they didn't clean the stage thoroughly.


Here is what wikipedia has to offer up on ammonium perchlorate (NH4ClO4) ...
"Like most ammonium salts, it decomposes before melting. Mild heating results in chlorine, nitrogen, oxygen and water, while strong heating may lead to explosions." Emphasis added by me. I just have a hard time seeing intact particles of propellant surviving the enviroment of a combustion chamber, no matter how fast they come out.

But the AP is still within the binder until it is exposed to the "burn front" (I made that up) no? so it doesn't melt until it is ignited. I'm just wondering if there is some physical process like ragged shocks that could dislodge unburned bits, especially just before shutdown. I'm REALLY reaching here.

Idle speculation: What about pyros ? There had to be a bunch going off in the EDL sequence when phoenix was out in the open ?

First go bring it back, then you can worry about dusting it off (I know you mean a ground spare / or reconstruction)

It does happen, and if the chunks get too big, well, the end result is like what happened to CONTOUR.

My instincts are still that perchlorate contamination from exhaust is a near impossiblity, especially with the exacting grade of fuel used in these kinds of rockets. But we'll see soon enough. I'm sure NASA and the Phoenix team will publically address all possible sources of contamination in a timely fashion.

No perchlorates. These use explosives.

Edit: I was mistaken here. NASA often times does use a zirconium/potassium perchlorate mix as an initiator in their pyros. I have no idea if they used such in Phoenix.

Seems like an easier path than sneakin' it in via the rocket motors. Prelaunch contamination seems unlikely to me because of the nature of the mission. Are there special clean room rules when you're worried about contamination spreading to your mission objective?

Of course! Just speculatin'. Good night.

And a pleasant evening to you, too.

I'm no chemist, so let me ask the chemists here... what happens when you take the boundary layer of ice, dust and small rocks (which may be rich in chlorine salts) and *melt* into it with hydrazine/nitrazine rocket exhaust?

Can the process produce small amounts of perchlorates? What all would you have to have in the mix in order for that type of event to produce perchlorates?

Let us not forget that Phoenix's rockets cleared off relatively large patches of ice and seemingly melted down into the ice at various points. I'm sure most of it exited the vicinity as rapidly sublimating steam. However, the MRO images clearly show that the entire area around Phoenix is covered with material ejected by the rocket exhaust at landing, and that material is *significantly* darker than the natural surface surrounding it.

Is it not possible that some of that color change is due to chemical alteration, and not solely from albedo effects in re stirred-up vs. eons-deposited soils?

Just putting it out there...

-the other Doug

I don't know if everyone here is so damned smart that they just didn't bother to comment on this, but ...

From http://en.wikipedia.org/wiki/Lithium_perchlorate :
"Lithium perchlorate is used as a source of oxygen in some chemical oxygen generators. It decomposes at about 400 °C, yielding lithium chloride and oxygen. It has both the highest oxygen to weight and oxygen to volume ratio of all perchlorates, which makes it especially advantageous in aerospace applications."



So, essentially the Martian surface is a repository of breathable oxygen? Pretty good diggin', Phoenix. (Yeah, yeah, all preliminary, I know - but one is allowed to dream.)

I note rocks precisely like that allowed the astronaut in "Robinson Crusoe on Mars" to survive in that sixties sci-fi movie . .

LOL, we are all catching up with 40 year old Hollywood Saturday afternoon movies now1

Yes sir -- and these chemical oxygen generators are both used in manned spaceflight, and have been involved in a couple of disasters.

The Mir fire occurred when an "oxygen candle" of the type described here started to release oxygen too fast, started burning too hot, and lit off a serious fire. Since the source of the fire was creating more oxygen than the fire was taking from the cabin air, it was an extremely difficult fire to put out.

Also, a jetliner (I think it was Air Blue, but I could be wrong) was lost, with all passegers and crew, when lithium perchlorate oxygen generators caught fire in the plane's cargo hold just after takeoff, and nearly burned the plane in half before it could turn around and land.

Sorry about the side-trip, here. But even though I know that these chemical oxygen generators can be very useful, every time I hear about them I shudder and think thoughts about nasty, hard-to-control technologies.

-the other Doug

I know, I get that. I didn't say confirmed discovery, I meant they've discovered/detected/sniffed something that's worth checking and has to be confirmed, that's all. This has been a good example of science-in-progress so that's still a result in my book, so well done guys, if you're reading.

Just squeezing this in after a late lunch break. In my opinion great credit to the Phoenix team - they have had the nerve to hold a delicate balance. They are leaders in open science but are also keeping their feet on the ground. More and more people (non scientists) are going to be close to cutting edge science in fields of key interest as we enter the information age proper. (Well beyond 1976!!!!). A significant number of scientists are going to have to develop new skill sets in the communications area! We are just in the middle of a particularly fascinating lesson in the basics! New ground is always unsettling! ....Especially watching the social and political implications of all this playing out.... and the funding implications! Openness has its costs. Yet imagine a general trend of widespread openness leading to a significant proportion (5-10%) of the general population being positively stimulated to move to a broader view beyond the generally held myth that science is pretty well cut and dried etc. etc. to the fact it hinges on empirical/intellectual exploration. Passive acceptance could become active interest. Interest become active support.

The Viking Labelled Release experiment is an interesting example of this sort of thing.....As I'm sure many UMSFers are aware, its echoes are still with us 30+ years later!!!

Interesting overview
http://www.space.com/scienceastronomy/viki...e_010905-1.html

Majority view - No life - interesting article on head of Viking Biology Team - Harold Klein, in terms of the subject we are talking about
http://history.arc.nasa.gov/hist_pdfs/bio_klein.pdf

Minority view - Life a strong possibility - by another of the key players in the Viking mission - Gilbert Levin (his company main designer of the LR instrument). See papers on his site.
http://gillevin.com/mars.htm

Speculative minority position on unusual life forms - by people like Jan Houtkooper
http://www.astrobio.net/news/modules.php?o...le&sid=2535

So...... I'm looking forward to 'our'(!) Phoenix Team uncovering more of the unknown in real time and so more surprises on Mars and Earth! When Peter Smith loses his beaming smile...well, in that unlikely event, we might have to start worrying!!!!

That's an inspiring opinion. I think that not only the scientists has to develop new skills, but also the public at large. We have to get used to the fact that when NASA says "these results may or may not be accurate" they mean it and give them time to complete the analysis and not overreact. If we can do this, NASA will have a much easier time involving the public in the scientific process, to the benefit of both parties.

As for the Labeled Release experiment, I never understood why NASA didn't make a follow-up experiment on one of their later lander missions?

I think this means nothing yet. We explore the surface and the near surface region... That's where oxidants form.

I really hope they will fund the Deep Drill lander someday.

The origin of the perchlorate (synthetic or natural) on earth can be asserted by δ 37Cl and δ 18O isotopic abundances. (See Fig. 1 in this NASA memorandum).

TEGA in principle might be able to measure these isotopic abundances with its MS spectrometer, and see whether it is a fuel contamination (which I doubt). We might also get to know what the deltas δ are for natural perchlorate on Mars in the process. However, since the perchlorate will be just one component in a composite mixture of soil salts, some possibly also containing oxygen and chlorine, it might not be experimentally feasible.

This book also has a chapter on perchlorate deltas, δ.


The pdf is here (access to Springer needed, I think).

We have an excellent example of interesting live science evolving here guys, let's enjoy it ! Go Phoenix


Edit to add postscript : After further reading, I think I was wrong about TEGA's ability to determine the perchlorate deltas. It seems to me now that it can't be done, at least directly.

As I understand, the first measurement got a borderline positive perchlorate measurement and the second negative. To do isotope ratios you need a strong signal--the water so far has not been enough to get O δ. The perchlorate story will get more interesting if the get a strong signal at some point.

Rumours have found their way even to Danish mainstream media...

http://politiken.dk/videnskab/article547315.ece

(Serious approach, talking about an "escalation in the blogosphere" compared to the original scanty information...)

Confusing press release I guess. Check out this from the SF Chron:



Perchlorate in the soil makes it Earthlike? In the words of Jose Jimenez: "Gee, I hope not."

Confusion may not be all the fault of the press. After all, perchlorate was detected in the same analysis as 8.0 pH and trace nutrients, the latter touted some weeks back as evidence of asparagus prosperity. Where was the scientific reserve there? Granted, perchlorate doesn't fit the narrative.

Does anyone know the freezing points of perchlorate solutions? If they are within the range of temperatures at the phoenix site wouldn't we expect that perchlorate in the soil would form small quantities of liquid and wick downwards? If so that would point to an active source, which adds evidence to the 'oxidisers fall out of the martian sky' arguments.

That was ValueJet, which shortly afterwards did a reverse-merger to become AirTran (since the old ValueJet name was associated with a plane-shaped hole in a Florida swamp).



Methoxylamine perchlorate can be mixed with hydrazine to drop its freezing point from about +1°C down to -55°C according to http://www.freepatentsonline.com/3941626.html

Thanks, I suppose it's the old more data needed scenario again.

Tuesday, Aug. 5, at 11 a.m. PDT .... - NASA teleconference on the subject.... 40 minutes from now.

Can one listen in to it anywhere?

No, this one is a special call-in for reporters. However, I'm sure they'll archive it online as they've done in the past, so you should hopefully be able to listen to it, possibly today.

--Emily

Hopefully those interested will be able to listen in:

NASA News Audio Live Streaming


COMING UP:

2 p.m. EDT, Tuesday, Aug. 5:
Phoenix Mars Lander

NASA will hold a media teleconference on Tuesday, Aug. 5, at 2 p.m. EDT to provide an update on the Phoenix Mars Lander Mission.

* A link to the streaming audio will appear here before the event.
http://www.nasa.gov/news/media/newsaudio/index.html

Streaming audio link is now up at that address, and working fine...

What a news conference ? !!!!!!

Keep your pants on, I'm sure they're just working out audio stuff or making sure the visuals (if any) are online and ready for journalists. I LOVE that NASA is willing to start a few minutes late in order to make sure that everything is working right. ESA will plunge right into a press conference even if people calling in from overseas can't hear a d*** thing or can't find the visuals.

--Emily

...soothing classical music?...

Edit: ok, it started now... - Thx for the link!