What you are suggesting will eliminate any ability to tilt the Rover once it bottoms out on the sand - ergo survival chances become severely diminished.

No, it doesn't. They've been methodical, serious and sensible. This isn't a rally car we're talking about, or a Ford transit van stuck in a dyke. This is a multi-million dollar scientific instrument, worth its weight in diamond-encrusted gold. They can't just rev up the engines and see what happens. Once it's gone, it's gone.

Backseat driving from a comfortable chair with nothing at stake is easy and fun. Being the people responsible for probably the most successful unmanned planetary exploration missions to date, with the whole world watching every move you make? Not so easy, and not so much fun. Does anyone really think the rover drivers and the people at JPL are happy to have Spirit sat there? Does anyone really think that they haven't filled trash can after trash can with balls of scrumpled up paper as they've worked through different rescue scenarios? Does anyone really believe that they've not agonised over how to save this fantastic scientific resource?

I don't know... call me naive, but personally, I'm inclined to trust the people who designed, built, launched, landed and now operate the rover to do what's best for the mission and the rover.

Just echoing Dan's comments here. I think perhaps the biggest reason that the drive attempts so far have been "cautious" has been the concern about sinking to the point that the belly contacts the ground. Once that happens it's game over. We've seen substantial sinkage with the drives so far, so "gunning it" now would almost certainly continue that trend. I haven't heard anything about what our clearance is now, but it wasn't good to start, and we have dropped quite a bit.

So I would say that the next things to try would be things that maintain some clearance with the ground. I am surprized that they're talking about using the arm already. I would've thought there still are quite a few variations of drive speed/steering/forwards/backwards/crabbing that might be tried first. Still, the update said they're only "developing plans" for using the arm at this stage. It could be some time yet before they actually try to use the arm.

In this type of situation where time, power, and options are running out, prepairing for the rover to be stuck here forever in my opinion has come and gone. This is a good place to study as long as the rover is operational, But moving along and attempting everything possible for extrication, even if its a stretch is worth every bit of risk. Planning to use the arm in a way it was not designed to do, with million's of dollars worth of instruments being actually considered by the MER team now, when before they said "that type of scenario is on the last on the list", clearly shows how dire things are right now. This is now critical time, and crunch mode now. More daring, high risk things need to be attempted before giving up.

Fredk, The sinkage has been substantial over drives yes, and that has only been over short drives that have not seen much progress. Soo..Whats left to TRY?? Considering the time and power remaining. *sarcastic* Ohh certianly not gunning it

AFAIK, the IDD arm is not needed for the types of activities they were considering in "fixed-lander" mode, such as seismology and weather reporting. Therefore, if using the arm is a last resort, it would seem they lose nothing by risking the arm in an extrication attempt. The arm is only useful if extrication succeeds.

If there is another extrication option that does no harm, it should be tried before using the arm. However, if there is an option that may foreclose the fixed-lander mode, then it needs a good chance of succeeding to outweigh using the arm.

Just to add my own view from the back seat, I would prefer it if they did not attempt to bury the front end deeper in the hopes of better winter survivability. Is it a certainty that Spirit could not survive in its current orientation? I mean, they are still trying to talk to Phoenix which had a much rougher go of it. I would hope they leave it as is and hope for the best. Then in the spring, when power climbs again, they could continue their efforts with a much longer period of time to work with. That might be all it takes, just a slow methodical approach a few mm at a time. If you bury it deeper, I think that pretty much dooms it to be a lander. Is it that important to have it serve that purpose? They still have one more shot at it on the other side of the planet should Oppy encounter a problem that affects only the mobility.

So, I say go for extrication till power levels drop too low, then shut it down to the bare minimum and hope it wakes up in the spring. If it doesn't,... well, I'm sure Stu and Astro0 will give her a lovely epitaph.

Brian

well, I'm sure Stu and Astro0 will give her a lovely epitaph.


[roverhuggermode]

We're a heck of along way from even considering it.
We know the Rover team won't give up on Spirit, be she a rover, a lander or a plain and simple 'damn heroic explorer'.

[/roverhuggermode]

I agree, Astro0.
Note that in another 3 more sols, on monday 18th, Spirit will be 100 sols away of living longer on Mars than Viking II, the record holder.
So...

Of late the approach with Spirit has been paralysis by analysis. With the FR wheel effectively drive dead any digging in with useable wheels will increase the tilt away from winter sun.
Has mission success been realized - yes a thousandfold.
Was backtracking to play it safe last winter the right decision - apparently not.
Did months of expensive analysis contribute to the escape - nope.

Accept that Spitits days as a Rover are gone and put the resources into Opportunity while she still works.

WITHOUT the benefit of hindsight - what would YOU have done?

Some of the hindsight induced backseat driving is frankly, a bit pathetic at the moment. I'm embarrassed of the place.

I'm still waiting for the images from today's extrication attempt; they should be available in less then an hour.
Meanwhile just say that the tracking wab info tells a different strategy is being used; the net result is 4cm backwards and 7mm upwards.

Whatever is done with Spirit, it will have no effect on how quickly Opportunity gets to Endeavour crater.

New Update:
http://marsrovers.jpl.nasa.gov/mission/sta...ll.html#sol2137

"Next, Spirit will switch directions and attempt to drive backward to see if that provides better progress."

Results of backwards drive

http://207.7.139.5/mars/spirit/forward_haz...F9P1154R0M1.JPG

http://207.7.139.5/mars/spirit/rear_hazcam...F9P1312R0M1.JPG

Nice to see the rear wheel again, hopefully this has helped tilt the rover in the right direction.

I must confess that I've lost track of the total forward and down.
Considering now backward and up, where are we as compared to initial situation?
I think Alan is right since, yes RR is visible again, but FL is sinking (I think), so the tilt has probably changed.

How do you get movement info from the tracking site?

The middle wheels have really dug in

Click to view attachmentClick to view attachment

Rear Hazcam....yes, it's nice to see the rear wheels rising from the sands
Click to view attachment
Animated gif - sol2145

Middle wheels - sol2143 to 2145 comparisons.
Click to view attachmentClick to view attachment

Hey the watt hours are only 225 ! What was the low value last winter ?

About the same, IIRC.

One thing that seems encouraging to me: the dust factor is about 54% right now; it was in the low 30's last winter. Doesn't this bode well for Spirit being able to maintain better power levels as the sun sinks in the sky? It suggests that the better dust factor will offset at least some of what can't be achieved by proper angling of the rover.

Well it looks to me like they can drive out backwards

I cannot imagine how pushing soil around with arm will do any damage.. Any why not do tiny micro-drives throughout the winter. A few wheel rotations per sol would be doable.

Some approximate power numbers from the same time of the Martian year in the past Sol sol 140 ~460 Watt hours, Sol 809 ~ 385 Watt Hours, Sol 1477 ~ 345 Watt Hours. 225 Watt Hours right now is quite bad but it's not remotely close to the lowest it's ever been (89 watt hours, briefly).

The dust factor (the amount of light blocked by the dust that has settled onto the panels) is only one of three main factors (in addition to the position of the sun). It degrades over time, faster in the periods after dust storms as the dust settles out of the atmosphere and the wind events that clear it up tend not to happen in the winter. The best thing to watch with regard to dust buildup is the trend and compare it to the dust factor at similar times over previous martian years. I haven't really looked into that recently but I've just pulled up some notes that indicated that the dust loss number on Sol 809 was around 41% so the current levels are pretty serious.

The second important parameter is the atmospheric opacity, tau. This represents how much light is blocked by the martian atmosphere and any dust still floating about in it. Apart from the major dust storm events when it rises dramatically it is (generally) higher (ie worse) in summer and lower (better) in winter however when tau is high the effect of the third parameter, the rover's orientation, is lessened too since more of the limited light available is diffuse. When tau is low (as it will be in deep winter) the benefit from having an optimal orientation of the solar panels can be 20% or more compared to a _horizontal_ orientation, having the solar panels pointing even marginally in the wrong direction when tau is low could easily drop power levels by 30% or more so getting into a good orientation for winter is of paramount importance as that is the only one of these factors that is under any sort of control.

The current levels are very low but they are not yet at the lowest levels that have been seen. At its lowest point in the mission so far Spirit generated 89 watt hours on one particular sol (Sol 1725 I believe, Nov 10 2008), averaging <170 watt hours for the 10 sols around that lowest point. Survival is unlikely for extended periods when the power levels are below 150 Watt hours and that is the number generally given for absolute minimal survival while still being able to remain under control. I'm pretty sure that even with the most extreme energy saving measures (turning off all survival heaters, no driving, no imaging, no science, absolute minimum comms) anything below 125 watt hours will be net power negative and result in a dead rover if it lasts for more than a couple of sols.

Edited to add: Just to get an approximate handle on how much lower the power levels can go the total insolation on the panels will drop to about 83% of their current levels when insolation is at minimum levels. The dust factor will generally get worse by somewhere between 0.1% and 0.3% per sol and we have about 114 Sols to go before insolation drops to its minimum (that happens a short while after the winter solstice). If nothing else changes those two factors will drop power from the current 225 Watt Hours per Sol to somewhere between 133 Watt hours and 167 Watt hours per sol. These are just my estimates, I could be wrong but I don't think I'm far off - the current position and orientation does not provide a good chance of survival.

Good comprehensive summary of the power situation, helvick.

I am optimistic by nature and will remain so as Spirit heads into winter. Your numbers, although not pretty, are at least hopeful. I think I remember hearing that 130 Whrs was the minimum for a rover in "starvation" mode. This was back when Oppy was threatened by the global dust storm -- July 2007 I believe. If that's the case, then your estimate of 133 - 167 Whr suggests that Spirit has a reasonable chance for survival. I am also hopeful that the new drive strategies will improve the tilt of the rover if nothing else. Not nearly what they achieved the past two winters of course, but even a few degrees would help.

If Spirit can do nothing all winter except send periodic "I'm not dead yet" messages, then so be it. Come spring those winds will whip up and she'll have power to burn.

Still picture with both rear weels again visible as said by Astro: http://nasa.exploratorium.edu/mars/spirit/...F9P1347R0M1.JPG
Click to view attachment

Rearward driving seems to be doing something.


Edit:


Rear Haz,

2143: http://qt.exploratorium.edu/mars/spirit/re...DGP1314R0M1.JPG

2145: http://qt.exploratorium.edu/mars/spirit/re...F9P1312R0M1.JPG

2147: http://qt.exploratorium.edu/mars/spirit/re...GXP1314R0M1.JPG


Forward Haz,

2143: http://qt.exploratorium.edu/mars/spirit/fo...DGP1214R0M1.JPG

2145: http://qt.exploratorium.edu/mars/spirit/fo...F9P1154R0M1.JPG

2147: http://qt.exploratorium.edu/mars/spirit/fo...GXP1212R0M1.JPG

Not trying to be optimist in excess but I think we're seeing a good performance. Fingers crossed.
Compare also the latest rear hazcam picture with the one at the beginning of the extraction attempts; we're already past that initial point.

Sol 2072: http://qt.exploratorium.edu/mars/spirit/re...00P1314R0M1.JPG
Sol 2147: http://qt.exploratorium.edu/mars/spirit/re...GXP1314R0M1.JPG

Do we know if they are instructing the rr and rf wheels to attempt to turn during these latest efforts?

How far have we come with this ride? As an amateur, I would guess that we drive about 2 centimeters backwards.

Could this be right? That would be an amazing progress, compared to the previous extraction attempts.

I never thought about it till now...
I thought about using the arm to raise the whole rover (impossibile, too heavy), to move away sand from above wheels, to put rocks over wheels (in such a way they are brought under wheels by wheels themselves)... but I didn't think the simplest way: can't the arm be used just to push forward while moving backward?!? Or is it this what they are doing now?

The idea of using the arm to directly push the rover (up, right, down, forward, backward, into the future, into the past, into orbit) has been discussed to a morbid, brutal, ancient death. The answer was always "Unfeasible."

In relation to the crater, what I see is a rotational progress, with the rear wheels moving outward and upward, but the front moving inward and downward. Are they still attempting extrication, or going for tilt? Maybe both? Can anyone tell what these last couple of drives have done to the tilt? And if they achieve a certain desirable tilt at some point, would they stop driving rather than risk losing that? So many questions...

Brian

What is the real significance of the rear wheels lifting and the middle sinking. With a rocker bogey isn't this a zero sum game?

When they were driving forward the middle wheels weren't bearing much weight because they were elevated. Now they are which takes some of the weight off of the non-functioning RR and RF reducing the drag they produce. Also the LR being elevated may eventually put it on top of the crust if Spirit is able to drive that far.

this was bound to happen sooner or latter

What?!

Nope, not yet...not by a long way. Patience.

Way to give someone a heart attack. Panicing, I searched the internets for a story relating to the loss of Spirit and I found a news article describing the loss of contact with Spirit, but it seems to have been from 2004.

Please don't do that again.

@JohnVV

Always bet on Spirit and Opportunity! They've surprised us in the past and I think they'll do in the (near) future :-).

Here's a gif showing the entirety of the backwards turn manoeuvre from the front, left hazcam.

(animation)

(forgive the double-post; max upload limit was already reached)

Here's the same sequence from the rear, right hazcam.

(animation)

Hey, that's quite a bit of movement away from that talcy dust pile! It's looking better ...... so being an optimist I am now taking RIP to mean Rover Inclining Positively or Rover Inching-Out Powerfully

this anim makes me think to a mole, or a worm... or to Tremors!

P.S.
How long did this walk take?

Thx Hungry4Info for those animated gifs!

It looks like rather stunning progress. Maybe after trying in vain to gingerly backtrack out of the quagmire, Spirit is now speeding right through it and charging out in a forward turn, no holds barred?

Would be one of the most amazing tales of interplanetary navigation if she comes out on the other side.

Not only has extraction not been abandoned yet - but the rover, even if stuck, is a long way from dead. Quite where you got the idea the rover is dead, I don't know. Please equip yourself with some facts before making posts in the future.

I'm sure most registered members here knew better than to take a cryptic "R.I.P", without any links to back it up, seriously. I just hope Guests weren't too worried by it.

I bet she isn't going to give up on the longevity challenge to the Voyagers, just because they have a few years of advantage.

ok,ok but at some point these two "energizer bunny's" will give out .

... and when our bunnies do that will be the time to wish them "R.I.P". Not before.