[X] My Assistant

[Guest_Actionman_*]

Driving at night might be better.

[djellison]

How would you conduct hazard avoidance in the dark? How much extra energy would you be spending heating the mobility system to allowable temperatures before moving?

And moreover....why might it be better at night anyway? I've attempted to drive across the sand in 40degF heat and 105degF heat....didn't change a thing.

[Guest_Actionman_*]

How would you conduct hazard avoidance in the dark? How much extra energy would you be spending heating the mobility system to allowable temperatures before moving?

And moreover....why might it be better at night anyway? I've attempted to drive across the sand in 40degF heat and 105degF heat....didn't change a thing.

You would use infrared time exposers with real time overhead data link. Or just do a short test and compare wheel slippage with the daylight data which you could after the fact..

[djellison]

You would use infrared time exposers with real time overhead data link.

The Haz and Navcam's are not IR cameras. They can not see in the dark.

https://www-robotics.jpl.nasa.gov/publicati...ne/fulltext.pdf

Their sensitivity is between 600 and 800nm. Thermal IR starts at 3,500nm

What is a 'realtime overhead data link'? Are you talking about returning data from MRO? That only happens for about a 15 minute period, twice a day, and the one-way light time is usually more than the duration of an MRO pass.

[Guest_Actionman_*]

Their sensitivity is between 600 and 800nm. Thermal IR starts at 3,500nm

What is a 'realtime overhead data link'? Are you talking about returning data from MRO? That only happens for about a 15 minute period, twice a day, and the one-way light time is usually more than the duration of an MRO pass.

1035nm MastCam with starlight is good for dune driving.

With just one peak form MRO it would be a short drive

But it could be worth it if the dune dust is more cohesive after it's cooled down.. say some time after midnight.

[djellison]

1035nm MastCam with starlight is good for dune driving.

MastCam can not be used for AutoNav.

MastCam will not see anything in 'starlight'

Moreover
-The MRO pass would not be long enough for an in-the-loop driving decision process.
-Earth may well not be visible during a night time MRO pass at Gale.
-The energy required to warm the mobility system to do this would be huge (if not entirely insurmountable)
-What evidence is there that 'cool' sand dunes offer more traction?

[mcaplinger]

MastCam can not be used for AutoNav.

I'm not 100% sure this is true, as it was discussed as a backup in case of Navcam failure during development. But it's certainly not assured; Mastcam is not even allowed to be powered on during driving at present.

As has been pointed out, there seems to be some confusion about how night vision works. I know of three flavors: image intensification of ambient light ("starlight scopes"), near-IR with active illumination in the near-IR (seen in some security cameras, baby monitors, etc.) and thermal IR. We can't do any of those with anything on MSL and the longest exposures we could take would be unlikely to even detect the ground. Near-IR works no better than visible for ambient light -- worse, because the sensitivity of Mastcam in the near IR is quite low compared to the visible. The best we could do is use the MAHLI LEDs for illumination, but the arm can't be deployed while driving and in the stowed position the LEDs aren't pointed in a useful direction, and they're not all that bright anyway.

It's an interesting idea that slip properties might change as a function of temperature, but I don't think there's any evidence that this might be true, and I don't think there are any known examples of it for terrestrial analogs.