Analyzing the conditions to establish viable colonies on Mars is one of the things that does not require a human presence on Mars. That can be done with rovers, albeit much larger rovers with more advanced features. I propose nuclear powered rovers as large as an SUV, capable of relatively high speed autonomous travel, and capable of taking 10 meter core samples and analyzing them. They should be capable of deploying some type of low altitude drones and/or balloons with high resolution multispectral cameras. The rovers can collect and transmit the images to Earth.Colonizing Mars is still in conceptual stage and it will get cleared only a set of people land on mars and analyze the conditions.