Fluency in english is required. Three references are enough. References that can address your qualifications to be part of this exploration program would be the most relevant. Scientific, engineering, practical mechanical, first aid, wilderness, and literary skills are all considered a plus. Dedication to the cause of human Mars exploration is an absolute must, as conditions are likely to be tough and the job will be very trying.
Team spirit is essential.
It would be desirable but not required that participants write a report on their experiences that could be posted on the Mars Society web site. The crew of the habitat is 6 persons. This is not certain and depends on the quality of applicants and the proposed duration for these applicants. See the web site for a summary of last years research activities. Preliminary plans for this years field activities will be posted in mid-February.