Universe Today
Water and supplies. The team Hansen joined had nine people and 29 checked bags for an expedition that lasted just over a week. They could also get water on site at a spot not too far from their camp, reducing the load of that heavy but important substance. NASA's long-range planning, meanwhile, envisions scenarios such as a month on the moon, Hansen said. Supplies would be an interesting and heavy challenge in that situation. "The next time we’ll go back, what we'll really be looking to do is travel much greater distances over a longer period of time," he said. "We'll be living in a rover for a month, covering 100 kilometers [62 miles] or more, looking for these important outcrops that tell us the story."
Geology. The Earth is an erosive force on geology: wind, rain, glaciation, water, volcanic activity and more alters the landscape. "Sometimes the rocks look very similar" even when they are different, Hansen pointed out. Other places may have different erosion processes (think micrometeroids), making the rocks look strange to Earth-trained eyes.
Location. The landscape itself could be challenging for collecting samples. The moon, for example, has "stuff strewn everywhere and pounded into sand", Hansen said, meaning that astronauts might have to travel much further to see something besides regolith or moon soil. Where Hansen was in the Arctic, by contrast, the group could get to more than a dozen different outcrops in a day of walking.
Gravity. The moon has a sixth of the Earth's gravity. Mars is at about 38% Earth gravity. This means that the machines would need to be designed to work in that environment. For astronauts, it's riskier to go up slopes or do heavy work in those conditions because their center of gravity is unfamiliar. As this Apollo 17 clip shows, astronauts sometimes fell over on the moon when doing something as simple as picking up as sample bag.