[X] My Assistant

[Steve G]

Tricky to line up the two RAC images but here is my attempt.

[Guest_Oersted_*]

Just looked recursion up in my dictionary:

Recursion, see Recursion

[climber]

Very interesting traduction in French = récursion

[dburt]

Just looked recursion up in my dictionary: Recursion, see Recursion

Thanks for that, which famously gets the basic idea across (lots of well-informed and clever people on this forum). Actually some of the dictionary definitions for recursive are worse, but I just meant the simplest: defined in terms of itself. As an example of a similar paradox, Paul Knauth told me that at the beginning of the semester, he likes to ask in class for a show of hands by "those students who never raise their hands in class".

With regard to Prof. Rosenthal and experimenter expectancy, I should have mentioned that modern social/medical scientists habitually engage in what is called double-blind testing. This means that neither the tester nor the subject know who is receiving say, the Coke or the Pepsi in taste testing. Similarly, in drug trials, neither the physicians nor the patients (or the rats, in animal testing) know who is receiving what - the new treatment, the standard treatment, or the placebo (cf. the famous placebo effect). In other words, zero special expectations by design. NASA seems never to have considered such a careful protocol for Mars, possibly because Mars the planet is neither a person nor an animal (although the story of the blind men examining the elephant comes to mind). Nevertheless, as implied in the post that started this commentary, when you are told to "follow the water" and are confidently expecting to find ice where you land, might this bias your thinking about the bright patch under the lander, or about other bright patches?

Another example might be if Phoenix identifies some (long-sought) carbon compounds. Our expectations regarding these as indicators of life might blind us to the fact that carbonaceous chondrites (a common type of meteorite) have been delivering copious quantities of organic compounds to the surface of Mars for billions of years. Although the scientists might be properly cautious about the significance of such an ambiguous discovery, the news media would probably be much less so (I can see the headlines now). The ultimate victims of the Rosenthal effect might then be the reporters (and thus the public), whose extremely high expectations for science itself could lead them astray.

Being well-informed and clever, I'm sure most of you can figure out why I bothered to explain this in such detail. (And I much regret that Alex Blackwell will not be making a uniquely dead-pan reply.)

-- HDP Don

[dvandorn]

I will point out that tests to make general-to-specific characterizations of large, complex systems don't lend themselves well to double-blind testing concepts. I mean, would you have the MERs bring along a suite of various rock types with them to Mars, selected by a group of people who have no communication with the PIs, and have every measurement taken on Mars include this test suite, with the PIs not being informed of which set of results belonged to native Martian rock and which to the terrestrial samples?

As you see, the specific double-blind process doesn't lend itself to the work at hand. Not that I don't see a need for some way to try and reduce the Rosenthal effect.

That said, what I note strongly in the process of designing science payloads for planetary probes is that it seems to reward those who have developed very detailed models of their expected findings, and have thence designed their instruments to most effectively collect the expected data.

It seems as if any experiment proposal that includes the phrase, in any form, "We don't know what we'll find" is automatically rejected because of the possibility that, by not meeting some preselected expectation, the experiment runs a high risk of being viewed as a "failure."

That's a process that not only allows a fair amount of the Rosenthal effect, it fairly demands it. When you design your instruments to show you only what you expect to see, it's awfully hard to see those things that *are* there that you never expected.

One of the worst examples of this effect, I think, was the life detection suite aboard the Viking landers. They were designed to say Yes or No to a very specific (and very terrestrial) set of life-bounded conditions, so the PIs didn't look closely enough at what Maybe results might mean, or how they might be interpreted.

I think the worst unflown example of this effect would have to be a contender for the 2001 lander program who, if I'm remembering the details from Squyres' "Roving Mars" correctly, wanted to devote an entire science payload to positively identifying amino acids within the Martian regolith. That would have been a good portion of a billion dollars to answer what is probably not *nearly* the most useful question to be asking.

The spacecraft that suffered the least from this effect? IMHO, at least for fairly recent probes, I would say Stardust. Yes, the designers of the Stardust collectors had to make some assumptions about the size of the particles they were going for, and the density of particles in their collection location. But the whole point of Stardust was "Let's go grab some comet dust, bring it back, and then see whatever we see when we get our hands on it." That mission design, since it brought samples back to where a great multitude of tests could be run on them as appropriate, was able to follow a more simple paradigm of "grab what you can and then see what you've got."

It seems to me, though, that until we can bring samples back and have the luxury of running whatever tests on them that seem appropriate (to answer all the new questions that the the initial test results pose), you have to narrow your data collection based on some form of triage theory. You can't fly all of the tools you want to fly that would truly enable you to just follow up on what you find rather than looking for what you expect. That's a given, considering mass budgets and funding budgets.

So, you *have* to narrow the focus to what you can afford to place in situ. Granted, the current process encourages that narrowing more than it should... but I'm not coming up with any good ideas on how to change the process to reduce the Rosenthal effect.

-the other Doug

[nprev]

Great post, oDoug!

That's exactly why I like the basic question that Phoenix is trying to answer: "Are there organic compounds on the surface of Mars in this locale?" That's constrained well enough to answer with the equipment available without making a whole bunch of other assumptions...good, focused science.

No disrespect to the Viking experiments intended, BTW. They were extremely audacious, but as Doug said there really wasn't very much interpretation space available for "maybe" results. We just don't know enough about both organic and inorganic chemistry in non-terrestrial conditions to draw definitive conclusions from any experiment designed to detect indirect evidence of biological activity.

[climber]

Yes, great post O doug,

This can lead also to "Mission success" requierements.
BTW, does anybody know what are Mission sucesses requirements for Phoenix ?

[MahFL]

This can lead also to "Mission success" requierements.
BTW, does anybody know what are Mission sucesses requirements for Phoenix ?

I found it....

Phoenix mission sucess criteria

[Skyrunner]

BTW, does anybody know what are Mission sucesses requirements for Phoenix ?

Minimum Mission Success Criteria
To achieve minimum success, the Phoenix Project shall:

• Land successfully on the surface of Mars and achieve a power safe state.
• Acquire a 120 degree monochromatic panorama of the landing site.
• Provide samples of the surface soil as well as samples from one depth beneath the surface to either TEGA or MECA wet chemistry.
• If TEGA, it shall analyze at least 2 soil samples to create a profile of H2O (in the form of hydrated minerals, adsorbed water, or possibly ice at the deepest level) and mineral abundances near the surface. It shall also analyze an atmospheric sample in its mass spectrometer.
• If MECA, it shall analyze the wet chemistry of 2 soil samples.
• Document all non-atmospheric samples and their collection locations with images.

Full Mission Success Criteria
In order to be fully successful, the Phoenix Project shall:

• Land successfully on the surface of Mars and achieve a power safe state.
• Acquire a true color (RGB), 360° panorama of the landing site.
• Obtain calibrated optical spectra of at least 3 locations that include both rocks and soil.
• Provide temperature and pressure measurements throughout landed surface operations at a frequency that determines key atmospheric properties.
• Provide samples of the surface soil as well as samples from two depths beneath the surface to both TEGA and MECA.
• Use TEGA to analyze at least 3 soil samples to create a profile of H2O (in the form of hydrated minerals, adsorbed water, or possibly ice at the deepest level) and mineral abundances near the surface. It shall also analyze an atmospheric sample in its mass spectrometer.
• Use MECA to analyze the wet chemistry of at least 3 soil samples. It shall also analyze 3 additional samples in its microscopy station.
• Document all 9 non-atmospheric samples and their collection locations (before and after sampling) with images.

EDIT: MahFL has beaten me to it:-p

[BrianL]

So, does that mean full mission success can be achieved without actually reaching, sampling and analyzing solid ice?

Brian

[centsworth_II]

So, does that mean full mission success can be achieved without actually reaching, sampling and analyzing solid ice?

It seems to me that mission success should be based analysis of the landing site, whatever the results of that analysis are. Also, let us hope that there is no layer of solid ice, especially near the surface, as that would mark the end of the dig, depth-wise anyway.

[Guest_Sunspot_*]

I want them to dig a MASSIVE trench !!

[ugordan]

Here's an animated gif of the digging. 21 frames spanning almost 2 hours. It's half resolution because the full res was too large to upload anywhere (9 meg). The overexposed part of the sequence covers 50 minutes and during that time no visible change in the white stuff can be seen.

Link to animation here

And an anaglyph of the resulting trenches:

[fredk]

Thanks for the animation and anaglyph. It appears to me that the bright "ice-like" surface exposed at the bottom of the trenches is not flat - there is relief to it. This is most clear on the right side trench.

I think we can expect more time-lapse trench images like this. On a recent press briefing there was an interesting comment from Smith I believe, who said that there was quite a discussion amongst the team about whether we were seeing true changes in the bright "ice" or whether it was just due to changes in illumination (phase) angle.

I guess this doesn't really fit in "RAC - Lander and Under-side observations" - perhaps we need a thread dedicated to trenching?

[ugordan]

To continue on the animation I posted and seeing the Phoenix team today alluded at hints of change of white stuff in time-lapse frames (change not necessarily illumination-related), here's a crop of the animation with two patches definitely fading out over time. Phase angle effect? It doesn't look that way to me, the neighbouring areas don't show nearly as much dependance. There's a frame each 3.5 minutes or so, except a 20 minute gap between 11:45 and 12:05. During this time the two spots change most prominently. There are also some smaller specks that appear to fade out, but they're not very conclusive. The rest of the bright stuff appears to not change at all or change very little.

Ice particles sublimating? Any thoughts on this?

[scalbers]

At the average ambient temperatures we expect sublimation to be quite slow. This might be accelerated by the action of sunlight shining on a dark bed of soil with a white ice particle sitting on top (if it is).

On another note, it seems remarkable that the ice could be just under the surface in such a wide area, yet there are no outcrops anywhere.

On yet another note (as I mentioned in another thread), I wonder if Peter Smith or anyone has commented on the "Holy Cow" image beyond what was briefly mentioned at today's press conference? It would be interesting to see how they would describe this image in front of an audience.