Winter Quarters, at Low Ridge Haven Options

[djellison]

Do you see any movement? I don't.

Really?

Load them both up and flick back and forth....there's motion

This is one image as a 'difference' of the other - the horizon has moved more than a little.

PERHAPS...here's a thought..it was a scheme to exercise the wheels, without actually moving anywhere, to minimise the risk of bad sticking when they come to use them properly in a few months time? I remember there being mention of motors having high currents when driving Oppy for the first time after the Olympia hiatus, probably due to the wheels getting a big 'draggy' after being parked for so long.

If they had powered each wheel in turn, just to give them a bit of exercise..they might not have moved, but they might have settled the rover a little?

Doug

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[fredk]

Load them both up and flick back and forth....there's motion

This is one image as a 'difference' of the other - the horizon has moved more than a little.

Doug

There is a slight overall vertical shift (4 pixels) between those two frames. But I can see no relative shift, ie parallax shift, between foreground and background objects (eg rover body and ground) on these images or on any of the series. Had there been any movement or rotation of the rover, we'd see such a parallax change. Instead the overall shifts in these frames must be just due to slight navcam pointing differences between the sol 807 and 855 frames.

In fact, when I first saw these frames I was impressed that they duplicated the pointing angles as acurately as they did!

[centsworth_II]

Had there been any movement or rotation of the rover, we'd see such a parallax change.

They could have moved the wheels as Doug said for excercise, but returned to the start position -- no net movement.

[Tesheiner]

Now that the exploratorium is back on-line, somebody could make the same exercise with the fhaz images:
-Sol 807: http://qt.exploratorium.edu/mars/spirit/fo...00P1274L0M1.JPG
Sol 855: http://qt.exploratorium.edu/mars/spirit/fo...00P1219L0M1.JPG

[fredk]

Here's a flicker gif comparing one sol 807/855 pair.

I guess the point of this new navcam series is to look for changes between sols 807 and 855. The local times of the two series differ by only 15 minutes or so, so probably the lower sun elevation as we approach winter is the biggest factor. Still you can see from the shadows in the gif that the change in sun angle isn't great.

In fact we can estimate that change by comparing the position of the sun's reflection in the solar panels between this image and this image. The solar panels act like a mirror to the sky! The answer is 6 or 7 degrees.

I see no changes in these frames apart from sun angle changes, at least for the ground. You can see quite a change in the sky though - the sky darkens over the 50 sols. I'm not sure how much of this is due to change in sun position and how much may be due to settling dust. These frames look roughly south, so the sun is farther from these frames on sol 855 than on 807. So I'd expect a darker sky on the 855 frame even without settling dust.

[djellison]

Odd - a drive number but seemingly without a drive.

Doug

[jamescanvin]

Very odd.

I see three possibilities:

1) They saw Michael Howards worry about MMB problems if too many image were taken at one site/drive number and decide to help out.

2) They 'tried' to move the broken wheel.

3) They refined there knowledge of Spirits position (there were a number of 'sun finds' at the time of the change) and defined a new site with the new values.

I'm not sure I beleve any of these though, a question for Jim Bell I think...

James

[Jeff7]

There are fresh hazcam images at the Exploratorium. I compared hazcam shots from April 12th with those of May 31st. Neither the front nor the back wheels have moved at all. That just leaves the middle ones - but even that is unlikely, as the hazcam pictures show no sign of movement either. Maybe the mast's camera's just aren't pointed at precisely the same location each time.

[fredk]

Maybe the mast's camera's just aren't pointed at precisely the same location each time.

Exactly as I suggested above! Does anyone recall what the pointing tolerances are like on these guys? Ie how accurately do we expect to be able to reproduce an old pointing?

[Tesheiner]

Very odd.

I see three possibilities:

1) They saw Michael Howards worry about MMB problems if too many image were taken at one site/drive number and decide to help out.

2) They 'tried' to move the broken wheel.

3) They refined there knowledge of Spirits position (there were a number of 'sun finds' at the time of the change) and defined a new site with the new values.

I'm not sure I beleve any of these though, a question for Jim Bell I think...

James

Right on the money, James!

From http://marsrovers.jpl.nasa.gov/mission/status.html:

SPIRIT UPDATE: Spirit Perfects Pointing Parameters, Collects Images Large and Small - sol 855-859, June 1, 2006:

Since arriving at the rover's current location on the 807th sol, or Martian day, of exploration (April 10, 2006), Spirit's knowledge of its attitude relative to the sun has drifted. The rover uses an onboard computer to keep track of attitude changes, but error builds up in this measurement over time. On sol 855 (May 30, 2006), rover planners transmitted an attitude update of 1.97 degrees to correct for the drift. After the update, Spirit re-acquired images from the same location to allow the science team to accurately target future observations.

[fredk]

From http://marsrovers.jpl.nasa.gov/mission/status.html:

SPIRIT UPDATE: Spirit Perfects Pointing Parameters, Collects Images Large and Small - sol 855-859, June 1, 2006:

Since arriving at the rover's current location on the 807th sol, or Martian day, of exploration (April 10, 2006), Spirit's knowledge of its attitude relative to the sun has drifted. The rover uses an onboard computer to keep track of attitude changes, but error builds up in this measurement over time.

Anyone understand what the nature of this drift is? I thought that normally this drift occured when the rover was driving, and hence accumulating errors while its orientation changes. In this case Spirit has been sitting still, and hasn't even settled according to the images. If it's orientation was known 50 sols ago it should be known as accurately tosol!

[Airbag]

Anyone understand what the nature of this drift is?

A small bias in the noise levels of the gyros that would add up to a measurable change over many days? But that would be true when driving too, so what is so special now? The rover can still update its orientation based on sun angles, which could (would?) reset the attitude vectors I would think.

Hm, a puzzle indeed...

Airbag

[helvick]

The rover can still update its orientation based on sun angles, which could (would?) reset the attitude vectors I would think.

The JPL update confirmed James' third alternative. The precision of the knowledge of the orientation of the rover was improved because they had many more sun pointing shots over time with which to refine the calculation.

[jvandriel]

Here is a short animation of the first 3 layers of "Progress" after brushing

jvandriel

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[hortonheardawho]

L456 Sol 858 sunset:

<a href="http://www.flickr.com/photos/hortonheardawho/159642548/" title="Photo Sharing"><img src="http://static.flickr.com/68/159642548_68c7f079de_m.jpg" width="240" height="180" alt="2P202552105EFFAS00P2669L456ar" /></a>

This is basically a test of Flickr copy and paste HTML.

OOOOK, Didn't work...

And Help does not discuss HTML tags...

Er, I'm sure this is a "simple" task?

How about this way: