Okay. What does this tell us? In the nighttime infrared image you should be able to see, immediately north of Curiosity, a light-colored splash on the Gale crater floor. Notably, it's a somewhat darkish area in the daytime infrared. This is an area of high thermal inertia, resistant to changes in temperature: it's warm at night, and cool during the day.

To put it in its geological context, look to the northwest of Curiosity. You will see a beautiful branching channel system, that once collected flowing water from higher elevations and channeled it into Gale crater. Where it breaks out of the crater rim it develops a mildly sinuous pattern, and it ends in a fan-shaped sedimentary deposit. This is an "alluvial fan." The water in the channel system ran swiftly in the steeply sloped terrain on the crater rim and so was able to carry rocks along with it. As soon as the channel debouched onto the crater floor, it flowed with much less speed so couldn't carry that heavy material anymore; the sediment fell out of the water, with the biggest cobbles being dropped closest to the wall. The finest clays continued to be suspended in the water until it flowed no more, so were left at the end of the fan. That's clay-rich material deposited out of flowing water -- exactly the kind of environment Curiosity was sent to Mars to study. That high-thermal-inertia unit may be a rock formed out of those fine clays.

On the other hand, it might not be. We're going to find out one way or the other, because that's where Curiosity is headed as soon as she starts driving.

Here's a few other bullet-point updates from today's briefing.

They'll start the drive after finishing Commissioning Activity Period 1B, during the so-called "Intermission." That's some time after next week. If they drive straight, it'll take 3 to 4 weeks to get there. (Go here for an explanation of what the Commissioning Activity Phases are.)

However, they might interrupt the drive to perform Commissioning Activity Period 2 activities if they spy an area of nice fine-grained material that will be straightforward to pick up and deliver to the SAM and CheMin laboratory instruments.

The DAN instrument operated successfully in active mode today, firing neutrons at the ground; furthermore, the RAD instrument detected the operation of DAN as expected. Grotzinger called this "great team collaboration."

The REMS weather instrument is operating and Grotzinger promised that its principal investigator would present the first results from that next week. The current daily maximum temperature is 276 Kelvin (3 degrees Celsius, 37 degrees Fahrenheit).

Roger Wiens showed an image of a little rock that the ChemCam team has picked out for their first shot, chosen more for its suitability for target practice than for science.

I asked about the Mastcam-100 (the zoom one) and they do not plan to go through their initial pointing tests and so forth until after Commissioning Activity Period 1B is complete.

They have not yet sequenced Mastcam-34 views that reach the top of the mound.

If 3 or 4 weeks seems like a long time for a 400-meter drive, it's because you're used to Opportunity's ridiculous one-sol drives of more than 100 meters. Remember, she was not doing that until way after her primary mission had ended, after her drivers had gotten very confident handling her on the repetitive, incredibly flat terrain of Meridiani Planum. It's possible that Curiosity will never achieve drives of that length, because all her flat-terrain driving is going to be early in the primary mission, when the drivers won't have achieved that confidence yet. By the time the driving becomes truly comfortable (though not easy -- it's never easy driving a rover on Mars!), Curiosity might already be in the much steeper terrain near the mound, and such long drives may not be possible.

Of course, I could be selling the rover drivers short here. For any rover drivers reading this, yes, that's a challenge. Achieve an over 100-meter drive with Curiosity and I'll bake you some cookies!