The primary objective of the current study is to develop a comprehensive understanding of the human requirements for space exploration in order to identify the specific and generalizable skills necessary to perform the work under operational conditions. For this reason, it was necessary to include descriptions of all tasks performed by each specialty represented by members of the Mars expedition crew. The Mars mission plans that were reviewed during the current study specified crew sizes ranging from two to 70, with six or eight considered by modern planners to be ideal to accomplish all mission objectives and to return to Earth safely. Most of the mission plans also assumed the crew roles to be Commander, Pilot, Medical Officer, Scientist (geologist, biologist), and Engineer (mechanical, electrical, nuclear). Among our goals has been to provide data-driven recommendations for the number of crew members and for their specialties. That is, no assumptions about crew roles were made during the study, rather, the results of the task analysis will lead directly to those recommendations. These recommendations will be presented in the future final report for this study.
Each task identified during the research was phrased to begin with an action verb, followed by the object of the sentence, and then a description of how and under what conditions the task would be performed; task statements concluded with the reason for the action, in most cases. For example: Enter control inputs, manually with gloved fingers, to override automatic firing of retro rockets for Mars Surface Descent maneuver if automated system fails.
The goal for this task analysis is to identify and record four specific elements of each task:
1) What is done?        2) To what is it done?        3) How is it done?        4) Why is it done?
Inspect circuit board, visually, to detect scorching or other evidence of electrical short.
Pound seismometers into rock, manually using slide hammer while wearing surface EVA suit, to deploy sensors.
View ultra-sonic display, visually while manipulating hand-held device manually, to interpret results of ultra-sonic imaging test.

We reviewed the task lists in an iterative process to ensure that task statements were phrased systematically, which would maximize comparability during subsequent data-collection and analysis, and also remove variable syntax as a possible source of experimental bias. The resulting lists of formatted task statements together provide our best estimates of the work that will be performed by members of the crew during an expedition to Mars, and the tasks for which they must be prepared to perform during emergencies.
The preliminary lists for the 12 Mars Expedition phases contained a total of 1,125 tasks, as illustrated in the table, below. Mars Surface Operations (MSO) has the largest number of tasks, which would be performed during the 18-months the crew remains on the planetary surface. MSO is followed by the Cruise to Mars and Cruise to Earth phases in numbers of tasks, which would be performed during the six-month transits to and from Mars. Many of the tasks are the same in the two cruise phases, but conditions will be different (i.e., before and after spending approximately 540 days on Mars); they are counted twice for this reason. Also, many of the tasks would only be performed in the event of equipment or software malfunction, or in response to medical emergencies.