I envy Cooper and Jeng. Yestersol they were pushed pretty hard to improve our rate of travel while remaining compliant with the Rules of the Road, and they came up with a good one (along with Mark Maimone). Essentially, instead of using visodom at 40cm intervals throughout the drive, they drive 5m at a normal rate and then did a clever slip check using visodom over the next 40cm. This does two or three visodom updates every 5.4m of travel, rather than the 13 or so we were doing over the same distance. This let them greatly increase our traverse distance; now we can attain the full 30m/sol we're currently allowed by the Rules, and do it in only an hour and a half or so.
I hate myself for not thinking of this. And I came in in such a good mood. Well, Jeng and I are going to pull the same trick thisol, and any sol where we have a nice long trough to drive in.
But maybe we won't drive south along the trough thisol. According to the orbital mesh, we're only 25m or so from the Erebus Highway. Driving there would mean driving at an azimuth of about 140deg -- across the ripples, not along the troughs, which would significantly limit our distance each sol.
I start looking into whether this is a sensible approach. What I find is that the images from our present location don't seem to agree with the orbital mesh. In our current images, we can't see anything that looks like Erebus Highway closer than 100m or so, putting it at least 6 driving sols away. (More actual sols than that, since we can't drive every sol over weekends and we're coming into restricted sols soon.) And even that's a gamble: it might be farther away, and it might not even speed up our traverse once we do get there. Meanwhile, we believe we can drive 30m per sol straight south toward Erebus itself. We talk it over as a team and decide on the direct route. But we're going to keep our eyes open, and if we see nearby Erebus Highway material, we'll consider going for it. If nothing else, we eventually cross something that looks like Erebus Highway -- Rob Sullivan calls it the Erebus Parking Lot -- even if we just head straight south.
So that's the plan.
Somehow we missed a major milestone. That is, a kilometerstone. Recently, the rovers' combined odometry crossed the 10km mark. And climbing.
[Next post: sol 549 (Opportunity sol 528), July 19.]
 A close descendant of this technique is used to check Opportunity's slip to this day. We also check slip only every 20m or so now, rather than every 5m, so the expense is even further reduced.