Winter campaign at Cook Haven, Sol 3512 - 3599 (December 13, 2013 - March 10, 2014) Options

[TheAnt]

Tonight on Ethel the Frog, we look at Opportunity's obsession that she is being followed by an enormous indurated breccia named Spiny Norman...

Monthy Phyton.

[fredk]

Oppy's continuing to produce impressive power for this time of year - just past solstice and she's up to 464 Whr!

From the latest update.

[MahFL]

I did not know they were using the IDD to crush rocks.

[climber]

Did you also note that people's pictures who write the updates didn't change till 2004? Oppy's still a young lady...

[RoverDriver]

I did not know they were using the IDD to crush rocks.

I didn't know it either, and I believe I was on shift that day...

Paolo

[Cruzeiro do Sul]

Oppy's continuing to produce impressive power for this time of year - just past solstice and she's up to 464 Whr!

From the latest update.

Whoa!! This last update show a solar array dust factor of 0,691 when the lattest were 0,610;0,590 and 0,594. So, a relatively big cleening event had happened during this last week. Thanks to wind god of Mars (the same of earth; eole?).

[serpens]

Good point Cruzeiro do Sul. It depends on which mythology you base the naming on I guess. In normal use here on Terra we tend to use the term Aeolian based on the Greek god of the winds Aeolus, although non traditionalists use eolian. But we are now discussing Mars and since that relates to the Roman god of war then we should probably use the Roman wind gods, Venti.

[dvandorn]

Both mythologies are referenced in scientific jargon. For example, you'll see discussions of aeolian erosion forming ventifact rocks...

-the other Doug

[Phil Stooke]

Aeolus held the winds in a bag. What did Venti keep them in? A really big cup?

Phil

[fredk]

Some details about the recent dust cleaning (venti-lation?) in the latest PS report:

"We’ve never seen anything like this before," said Bill Nelson, chief of MER engineering. "Normally, a dust cleaning is a one or two day event and we get a jump in power. Here we've seen a continuous rise over weeks. Instead of dust building up a little bit every sol, dust has been blown off the array a little bit every sol and the power has gotten a little better and a little better and a little better."

Why Opportunity has been experiencing this ongoing dusting is anybody's guess right now. "We seem to be in some kind of a wind channel," said Nelson. "We’re thinking it’s some combination of the rover’s position on the crest, on the edge of the crater, and the way the winds are blowing or circulating through Endeavour."

[Astro0]

After reading that in the report I was immediately thinking about the way that sand blows off the top of a dune keeping it almost in continuous motion even in the lightest of winds.

[marsophile]

I wonder if the simple fact of being tilted could affect the deposition/removal "budget" so that a small net deposition could be transformed to a small net removal.

I think the total tilt (vector sum of North/South and East/West) has been greater recently than at most times in the past. Perhaps that might account for the steady improvement? If this is so, then it might be useful to seek a tilt (perhaps East/West) even during other seasons besides winter.

[fredk]

Spirit overwintered on the northern edge of Home Plate and got some pretty extreme tilts, but I don't recall any particular effect on dust coverage.

My guess is that the gravitational forces on dust on a tilted panel would be tiny compared to the wind forces.

[dvandorn]

I don't think it's just a matter of tilt. It's more effective for dust cleaning to tilt into a prevailing wind, I think -- it increases the force of the wind for the surface to be more perpendicular to the airflow. Obviously, the edge of Home Plate wasn't an area where there was much prevailing wind. I'd guess there is more wind where Oppy sits now than there is down on the plains. I think the two -- a windy location plus a tilt into the wind -- worked together to create a gradual cleaning effect.

-the other Doug

[ngunn]

That sounds right to me. A location where the hillside already faces into the wind plus an extra tilt of the panel in the same direction does the job. The dust is being swept upward off the surface, not sliding downward due to gravity, so tilting alone without the prevailing wind and the right topography would accomplish nothing.

The fact that this is a location where loose surface material is preferentially removed by wind may be part of the reason why we're at this spot.