Heiko viefhaus

Enjoyed the film but the glaring plot hole really annoys me The MAV he uses to leave Mars at the end He says it was a pre supply ship for the next Aries mission. Given that they evaluated in the middle of the storm in the beginning because they were concerned that their MAV was about to blow over, how long is this thing left sitting there at risk of the same? If it was still on route why didn’t they get it to land closer to Matt and save him the long dangerous journey? And what supplies were on board if not food?