Looking at your gear list, it's unlikely to be the lens or the support.
Given that you're photographing at what appears to be mid-afternoon in Egypt's Western Desert, heat-related interference is the main suspect - you may have better luck early in the morning, before the ground and air heat up. When I was recently photographing volcanoes in Ethiopia, I couldn't get a remotely useable shot of the glowing lava even at 200mm and 1/2000fps, due to heat-related interference...
The other possible cause is depth of field - is it sharp anywhere in the photo, or is it blurry throughout?