Similar distance as on the previous one: 95m. One more drive and we may be reaching the 36km mark.

Did they zero the odometer before deployment or did it still have acceptance test distance logged, compensated for in the distance / direction from start point software? ie. The distance on moon will be less than the total recorded? Comparing the Apollo rovers to the MER is really a chalk and cheese approach and the outcomes depend on how you squint when assessing. For example: if you look at distance and time deployed the Apollo 15 rover is the champ. 0.152 kilometers per minute. Apollo 17 comes in second at 0.135. Opportunity can go down in history as the slowest ever rover in terms of distance /time.

Yes, they zeroed the nav system several times during the EVAs. And the system only told you the range and bearing back to the LM. Total odometry was calculable from this (it was calculated on wheel turns), but was considered somewhat of a "dead reckoning" system. Wheel slippage and meander to avoid rocks and craters meant that the nav system would get you back to where you could see the LM and drive back to it by eye. No one ever pretended that it could tell you within a few meters *exactly* where you were or how far you had driven.

On the LRV, the range and bearing were more often used in finding the planned station stops, and due to the various small detours and wheel slips these readings usually varied from the pre-mission calculated values, even when the slight variations in landing point were taken into account.

All this is to say that you'd have to do the kind of detailed wheel-track analysis they're now doing with the Lunakhods to get the absolute exact distance traveled by any of the LRVs. There is a "wander factor" in the LRV nav data that makes all calculations based on them somewhat approximate.

-the other Doug

You could make up a million different statistics all pretty much as meaningless as the next. Distance travelled vs average distance from earth. Distance travelled per KG of vehicle mass. Number of individual drives. Number of locations visited. Total longevity etc etc etc

Interesting stats would be long distance targets like Endurance or Victoria or Endeavor and what was the average drive length when heading towards these goals. Before embarking on the trek to Endeavor folks were doing some math about how long it would take.

btw, didn't we have a pool guessing the arrival date at Endeavor?

We had one long-running poll here years back and the back-and-forth arguing both during the drive and after the goal was reached became so annoyingly dull that polls have been banned here ever since.

Sol 3312 panoramas :

Navcam


Pancam, drive "yes it's good to read drive " direction :

Exactly my point. Comparing the distance achieved by a lunar 'car' and a martian robotic rover is meaningless. The really big deal is comparing the longevity and distance achieved by Opportunity compared to design requirements and mission success parameters. I have used Opportunity as an example of outstanding reliability engineering and remote diagnosis and rectification. I stand in awe of those who designed and built her.

JPL engineers admitted the MER's were overengineered and that the 90 day mission time was very likely to be exceeded, barring some unforseen problem. So comparing to the 90 day required time is not really a valid reference point. The main reason Sprit died was it got trapped in sand and could not tilt it's solar panels to the Sun. That of course could have happend on the first drive if fate had meant that to happen.

I assume you mean MER.

I can assure you - all mechanisms etc are tested to 3x the required lifetime. That's not 'over engineered' - that's called engineering margin to guarantee a good shot at reaching your requirements. It's JPL policy. It puts the bellcurve of expected failure centered beyond 90 days.

Squyres has been on record - years after landing - saying he thought maybe 120, if everything went perfectly maybe 180 sols. I'd be interested in exactly where you see JPL engineers describing MER as 'overengineered'. That's not a phrase I've ever heard them use. Required engineering margin....yes. Not 'overengineered'

Plus - the dust was STILL expected to kill the rovers very shortly after 90 sols. This paper by the late great Jake Matijevic details the expected liftspan of the rovers...

http://trs-new.jpl.nasa.gov/dspace/bitstre...9/1/02-0732.pdf

Slide 3 explicitly states that the expected useful lifespan of the rovers was 100 sols for MER-B at the 'Hematite' site ( aka Meridiani ) and 92 sols for MER-A at Gusev.

So - maybe you might find an engineer on Sol 500 saying "We obviously tested for more than 90 sols". But BEFORE launch - I challenge you to find any engineer on record stating they expected the rovers to last significantly longer than 90 days. I don't think you'll find it.

I think I may have equated 'margin' with 'over engineering'.
I still think though the team was staying with the 90/180 day thing, as the costs for a 10 year mission would not have been at the time favorably looked at by the beancounters...... . There was even conjecture at one time one rover would be turned off to save said beans .

I counted 999 Sols, Distance 21.12285 Km, 357 drives, 21.14 meters/sol 59.17 meters/drive

Paolo

Thanks a lot Ant103 : those views are impressive in the sense they show a virgin territory yet to be explored in front of us, really devoided of any tracks and marks.
A real sence of loneliness here from your pics. This is what I call an "unknown territory" !

And the paper I linked to proves otherwise.

Here's an "enhanced version" of a FHAZ image taken during sol 3314.