In addition to cats not liking zero gravity they also need to eat and drink. This adds to the difficulty to maintain a healthy cat while in space. This would be even more challenging on a long trip like to the planet Mars. The average cat would eat around 1/2 cup of dry cat food a day which over the course of about two years would be around 360 cups of dry food. That would be about 100 pounds! This doesn’t even count for the water, litter or other items the cat would need to survive.
Here is a link to a website that tells you how much food you should feed a cat: