It belongs to a company called Penetradar. They use ground-penetrating radar to evaluate pavement - as in this image from their website. It's also great for analyzing bridge decks.

MoDOT is planning to start some bridge work in the Columbia area soon, so the van is gathering data. That information will help identify issues within the bridge that need addressing before a single cut is made in the pavement.
That helps the repair contractor. They'll know what they are facing before they open the surface. Fewer surprises make for less stressful, more profitable work.
It helps MoDOT. Fewer surprises make for fewer last-minute (often expensive) fixes and keep work zone time to a minimum.
But most of all, it helps motorists. When a contractor knows what they'll face, they can "operate" and get out of drivers' way more quickly.
Now...this will only hurt a little bit...