"The last winter-preparatory movement of the rover was commanded on Sol 2169 (Feb. 8, 2010)."

Right on UMSF anniversary! She's so sweet.
Good luck an again

(Moved the latest posts related to power levels / management to the other thread)

Not sure if it's the right place to pots this, but...

Several new images are down from Spirit, showing more coverage of the sinking. I've stitched them together in an animation.

Thankyou for the animation. This is Spirt's best shadow puppetry yet. What I see is a dragon with a long snout and big ears.

She looks on the ground to me in these latest MI's from Sol 2174.

http://marsrovers.jpl.nasa.gov/gallery/all/spirit_m2174.html

With the latest downlink all of the "cleat cam" images are now down.

Right Forward:
http://www.youtube.com/watch?v=xIgRanViVc8

Right Rear:
http://www.youtube.com/watch?v=yb-u1XwZx-Y


I highly recommend you view it at 720p.

Just found this sequence on the imaging plan for today, sol 2177. Last time I saw one of those was almost 300 sols ago.
Maybe preparing the spring extrication campaing?

02177::p2398::19::8::0::0::8::2::18::pancam_drive_dir_4x1_L2R2

Look... in the hole on the left there... a Lucky Horse-shoe?

Click to view attachment

That has to be a good omen for the Spring...!

I really like Scott's comments in his blog about Spirit's progress last time we moved and the possible plans for spring.

Scott mentions "when we resume extrication efforts later this year", which presumably means later in this calendar year, so before January. Is Spirit not still committed to 6 months of stationary science after it wakes up before it does anything else? Or will they continue extrication, and then have it sit? Is the whole stationary science decision being reconsidered given that there now seems to be a good chance of getting Spirit out of this sand pit? Or at least postponed to be done during a subsequent winter haven where they can give the rover enough tilt to stay active through the winter months?

It's a see-how-we-go situation.

If the thing gets cleaned to 800Whr+ come spring, can you really imagine them sitting still and not trying to get out?

Scott told me that they can actually move some centimeters without affecting the radio science campaign, so they can continue working on extrication efforts up to a point even while they are considered "stationary." In the event that they find they are successful and could move so much that they would ruin the radio science experiment, my impression is that the radio science experiment would be completed first, but obviously that's a decision that would be made if and when they actually face that situation.

In view of all the signage going up on Meridiani, I thought Spirit could use one.

Click to view attachment
Using Stu's "Stuck" image.

Does anyone have an image of the area taken by Spirit where she is stuck now? I would like
to see a ground level shot of where she is now and what direction she is going from that spot.
There is probably an image somewhere in an earlier thread. I just want to know if she has
to go up hill from where she is now to escape the sand trap???

Thanks

The post previous to yours - with added rover for scale and perspective - is EXACTLY that.

Thanks Doug.

Sols 1406 to 1782 (=386 sols) saw only small movements down the slope at Winter Haven 3. Tesh's maps are not quite accurate enough to estimate the minimum number of centimeters moved over a six month span, but whatever it may be, isn't that an upper bound for the amount of permissible movement during the core composition experiment? IIRC Spirit was able to call home during the previous winter, and yet the stationary observations that could have been done then were apparently not accurate enough. Anyway, it seems to me that if we are going to perform such a sensitive and difficult-to-repeat experiment, the observation error ought to be reduced as small as we can possibly make it by just keeping the rover stationary. I don't understand how some error can be permissible and more error can be impermissible.

I can speculate. The wavelengths are 2-4 cm and the frequencies are 12-8 GHz. A few cm movement of the rover isn't a big deal... it's still in the same place as far as the experiment's accuracy is concerned.

There was an entire press conference on this topic and they went round and round on the issue of small movement. Ultimately, what Scott told Emily was described as within the tolerances of the experiment. I don't see why that is difficult to understand. Have you ever used a measuring tape to find the length of something? Did you stop to worry that the molecules at the end of the tape are vibrating back and forth the entire time? It doesn't affect your measurement though because that movement is within the tolerance you have accepted for that datum.

Doug and I measured out the whole solar system with a tape measure last year, and I can honestly say that by the time we got down that long hill to Pluto, the state of the molecules at the end of the ******** tape were not foremost in our thoughts...!

Is there a transcript of the above mentioned press conference available somewhere? I am interested in this experiment and I want to understand it better.

Meanwhile, limping along on what I have read and heard, I am reasoning as follows:
To build on the tape measure analogy, measurement error can usually be discounted when the question at issue is binary.
Like: "Will this bookcase fit through the door of my den?" Even with just a centimeter to spare, it's a done deal, unless I have a very badly frayed tape measure or I confuse centimeters with inches or something like that.
If I thought the center of Mars was either wholly liquid or wholly solid, (whatever that means when applied to metals) it would still be a binary call and measurement errors less than a certain size would probably not affect whether the hypothesis is to be rejected or sustained.
But in this case there are a number of continuous variables to be estimated - coefficients of plasticity, or the diameter of whatever "liquid" core may exist.
If I take your photo, your face may be recognizable even if my hand trembles or you blink your eyes. But photographers usually try to minimize that noise to get the best picture possible.
BTW, if we are going to sacrifice some measurement accuracy to perform an extrication maneuver essential to Spirit's survival, I am OK with that, but it is not the same argument as saying that movements of less than n centimeters do not have consequences and movements of more than n centimeters do have consequences.

I think you'll find that it is not centimeters that are being measured, but doppler shifts and times.

Phil

What matters is that the movement of the rover is small compared to the relevant scale. No doubt the rover shifts a bit each time the wind changes direction, but probably by only a very small fraction of a millimetre. Surely such movements would be unimportant for the core studies, but those same movements could be critical for the seismology experiments.

In the case of the core studies, there is some relevant scale, but I don't know what it is. As mentioned above the signal wavelength sets an absolute lower limit to movement that you'd care about, in the cm range. There could be many factors that make that lower limit larger. If it was several metres, then movements of tens of cm would be unimportant. The errors induced by the rover movement would be swamped by other errors.

Another point is that it might be that the movements could be corrected for in the core studies. Remember that the driven rover movements aren't random noise - the distances and directions and orientations are known with high precision.

Edit - definitely you're right, Phil, that cm are not measured directly. But still the relevant timing errors correspond to some position errors, since the signals travel at a fixed speed, 300 000 km/s.

So as I see it, they measure the effect of Mars' wobble on Spirit's radio signal in real time. Spirit can move between measurements without the overall study being effected. It seems to me that a much bigger problem would be motions due to thermal changes or a stiff breeze during the measurement.

NASA - Spirit's Journey to the Center of Mars
"Mars wobbles, or precesses, as it spins," says Bruce Banerdt of NASA's Jet Propulsion Laboratory. "We'll measure that wobble by looking at the Doppler shift of Spirit's radio signal."

Well, since it is the doppler shift they're interested in, the distance of the Spirit from the center of Mars affects its radial velocity, so that movement upslope...

...is going to be a probably immeasurable difference.

Actually, compared to the frequency variability implicit in the temperature of the oscillator on the rover... yeah, it would be very lost in the wash.

I don't know the techniques being used on the ranging experiment but two points seem (at least theoretically) relevant.

1) The signal's wavelength need not be an absolute lower limit for position. If they're measuring phase shift of the received signal, they can probably get down to a fraction of a wavelength. (Precise GPS surveys do that all the time although in the Earth-Mars case the signal strength is much lower and it may be much more difficult to do.)

2) The stability of the local oscillator on the rover is not relevant to a doppler signal, where the frequency is set by the stability of the signal transmitted from the Earth ground station, received by the rover and retransmitted (perhaps with some alteration) back to Earth.

Steve M (talking outside his area of expertise).

If Spirit manages to move over a meter wouldn't they still be able to do the measurements if they knew the distance moved to an accuracy of less than a cm?

Yes, that is another very reasonable question to ask - why can't they correct for known movements? But in that case they certainly could have performed the experiment during the 1+ Earth years spent at Winter Haven 3. Those little movements inching down the slope were very precisely calculated.

I'm going to say "no" and go way out on a limb with why I think not. With all the variables involved in the absolute distance between Earth and Mars in three dimensions, my guess would be that the uncertainty for the location is not linear since we are looking at variations along all three axis in 3D space. The equation accounting for the uncertainty of the distance from Spirit and a defined point on Earth more than likely describes the volume of a sphere. By changing Spirit's position I would assume that the radius of that uncertainty sphere is being increased accordingly, and therefore its volume is increasing exponentially.

Scott mentioned to Emily they could move Spirit several centimeters. If that means the base uncertainty is something like 6 centimeters, the uncertainty sphere would be 904 cm(3) in volume. If you move the rover a distance of one meter (100 cm) then the radius would be 106 cm with a volume of 4,986,387 cm(3). Comparing the volumes of the two spheres [4,986,387 cm(3)]/[904 cm(3)] it would seem that by moving the rover one meter it creates an uncertainty over 5500 times as large as the 6 cm uncertainty where she now sits. It certainly shows why extreme minimal movement is necessary for this experiment.

That presumes that any old observations will do--not true--or that "could have been done" = "were done"--not true (at least in the quantities needed). The experiment needs passes other than what would be chosen normally, extra DSN resources, and extra energy on Spirit. Precise speed measurements with doppler shift require a to/from velocity component, so Earth has to be low in the sky. Winter direct-to-Earth comm tends to be associated with Earth being high in the sky.

I think there are a couple issues with motion. Personally, I think motion during a specific precession-pole-measurement would be bad. Such a measurement might be done in a sol, but might stretch over a week given whatever the energy situation is. Second, movement over the course of the campaign has never been ruled out, to my knowledge. It's just that the uncertainty added by that needs to be at the 1-3 cm level (balance between being sufficiently better than current knowledge and being lost in other noise sources--no I don't know details). So I'd guess that moving 3 m might be OK; moving 30 would very much not be. So that could give Scott et al. plenty of room to play before they get to the end of the leash.

I dropped by the office of a few friends last week who happen to be rover drivers.

In case anyone was wondering, Spirit's sister in the testbed at JPL is also still stuck and waiting out the winter.

And can we have a round of applause for Paolo and Kim, the two people who spent much of last year up to their eyes and ears in dust and dirt and many hours out in the back parking lot of JPL in the blazing sun concocting mixtures of various dry powders to simulate martian soil? While the rest of us were sitting around looking at images typing, "turn this wheel", "turn that wheel", "go faster", "use the arm" they were out there performing the difficult and unglamorous tasks of creating a pile of dirt in Pasadena like the one on Mars.

Yes! We definitely have to say 'Thank-you!" for all of the hard work.

My Heart felt thank-you. May we hear from Spirit soon!

Applause indeed!!! How is Paolo? Haven't head much from him of late.

So shall we say seconded, thirded and motion passed! Thanks Paulo and Kim!


Lets hope our little buddy pokes her head up soon.

I know I get a little jump in my heart rate whenever I get a reply notification to the forum.

Scott Maxwell has indicated on his Twitter account that Spirit may be moved a few meters before it starts its radio science experiment:

Spirit hibernated (in trap) for Martian winter. We've started trying to reestablish contact. Will resume extrication.

This makes sense to me. If Spirit is to become a stationary lander for two or three years then it seems sensible to me that it be moved 5m or so to a new location where it could better survive the next Winter. I believe that a slight slope to the North would provide sufficient power for both Summer and Winter operations.

I do believe that Spirit will eventually manage to traverse the 100m to Goddard crater. However, this epic journey may well have to wait until the radio science experiment is complete. In the past I have imagined a race between Spirit and Opportunity and wondered whether Spirit would reach Goddard before Oppy reached Endeavour crater. My ideal location for Spirit to park for a time as a stationary lander would be on the North facing slope leading up to Goddard crater.

How can i know which day of the year is currently on Spirit position? I mean, is it today july-10th-like day rather than february-3rd? I know it's spring right now... but is it march-21-equivalent or june-21 equivalent?

Go here:

http://www-mars.lmd.jussieu.fr/mars/time/martian_time.html

Enter today's date, convert to Mars Date and Solar Longitude, and check out the explanation of Solar Longitude in the link at the top of the page.

Phil

Mars24 also shows LS and the season.

Thanks,
I also found this:
http://users.zoominternet.net/~matto/Java/...rsion%202_0.htm

But they give different result: first site says it's month 6 ("scorpius" month, as per table in second site), but second site gives day 10 of "Sagittarius" month , which is 7th.

Does this mean june-equivalent?(or july-equivalent)
Shouldn't it be march- or april-equivalent?

There are a large number of different Mars calendars, and they divide months up in different ways- roughly equal number of sols, equal angle of solar longitude, etc. So you can't expect to find the same result, in month terms (or even in when the year starts, or which year it is), from different sites.

The site I gave is the only one in anything like common use among Mars researchers, and so it's the one I have used for Mars dates in a forthcoming book. But I ignore months and only refer to the Mars year and sol.

As for the month for Spirit - I think they need to go into early summer to get it going, not just spring.


Phil

From here, some dust storm activity over Spirit:

This could be good or bad news - cleaning events have been associated with dust storms before.