Mars Expedition Crew Composition

By Joseph Jimmerson

The purpose of this study is to investigate the optimal crew size for long-duration space missions, specifically the first manned expedition to Mars. Manned space mission design is based primarily on the crew size, so this information is critical from the onset of mission conception. An initial position was established by reviewing mission reports, plans, and related crew studies. Data was gathered by surveying a population of crewmembers from various fields who work in environments similar to those encountered by a Mars expedition crew, to include astronauts, Antarctic and underwater research teams, air crews, analog mission crews, and missile crews. The researcher showed that larger crews, while more demanding with regard to vehicle, trajectory, life support, and overall mission design, are better suited for such long duration missions.

• Language: English
• Publisher: Lulu.com
• Release date: Mar 31, 2011
• ISBN: 9781257317943

Book preview

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MARS EXPEDITION CREW COMPOSITION

by

Joseph T Jimmerson

A Graduate Research Project

Submitted to the Extended Campus

In Partial Fulfillment of the Requirements of the Degree of

Master of Aeronautical Science

Embry-Riddle Aeronautics University

Extended Campus

Vandenberg Resident Center

October 2005

eISBN: 978-1-25731-794-3

MARS EXPEDITION CREW COMPOSITION

by

Joseph T Jimmerson

This Graduate Research Project

was prepared under the direction of the candidate’s Research Committee Member,

Mr. John Cunningham, adjunct Associate Professor, Extended Campus,

and the candidate’s Research Committee Chair,

Dr. Alexis Olds, Associate Professor, Extended Campus, and has been

approved by the Project Review Committee. It was submitted

to the Extended Campus in partial fulfillment of

the requirements of the degree of

Master of Aeronautical Science

PROJECT REVIEW COMMITTEE:

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John Cunningham

Committee Member

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Alexis Olds, Ph.D.

Committee Chair

ACKNOWLEDGMENTS

I would like to thank those who deserve special recognition and helped me complete this project. To Otto Rutten, Mark Nelson, Jamie Candelaria, Robert Zubrin, Tony Muscatello, Dan Dorson, and Don Landgrebe for their assistance in survey distribution and administration. The surveys were crucial and had to get to the right people – they made it happen. Of course, thanks to all the aquanauts, missileers, aircrews, Mars Society members, astronauts, Biosphere II members, and others who participated in the survey. Thanks to all the Embry Riddle graduate students who tested this survey. A special thanks to Sharon Fry and Dr. Horst Liebel for getting me started in the right direction, and to my GRP committee for their guidance and encouragement. Finally, thanks to my wonderful wife whose understanding, support, encouragement, and occasional prodding made this all possible.

ABSTRACT

Researcher:    Joseph T Jimmerson

Title:              Mars Expedition Crew Composition

Institution:      Embry-Riddle Aeronautical University

Degree:          Master of Aeronautical Science

Year:             2005

The purpose of this study is to investigate the optimal crew size for long-duration space missions, specifically the first manned expedition to Mars. Manned space mission design is based primarily on the crew size, so this information is critical from the onset of mission conception. An initial position was established by reviewing mission reports, plans, and related crew studies. Data was gathered by surveying a population of crewmembers from various fields who work in environments similar to those encountered by a Mars expedition crew, to include astronauts, Antarctic and underwater research teams, air crews, analog mission crews, and missile crews. The researcher showed that larger crews, while more demanding with regard to vehicle, trajectory, life support, and overall mission design, are better suited for such long duration missions.

LIST OF TABLES

Table

1 Skill Type Matrix

2 Selected Literature

3 Number of each population group of respondents

4 Number of Respondents’ Missions

5 Longest Mission Duration values

6 Total Mission Duration, in days

7 Experience Questions

8 Crew Position/ Skill Set Response Data

9 Mars Society Popular Duties

10 Results from crew of Biosphere II regarding ideal crew size

11 Researcher’s Ideal Crew Composition

LIST OF FIGURES

Figure

1 Opposition Mission Trajectories and Timeline

2 Conjunction Mission Trajectories and Timeline

3 Mars Direct Mission Architecture

4 NASA’s stepped approach to Mars

5 LMLSTP Facility

6 Biosphere II Complex

7 MDRS in Utah

8 Wernher von Braun’s Mission to Mars

9 Skill Set Chart

10 Survey Population

11 Sample Population’s Relevance to Study

12 Combined gender and military experience

13 Mars Exploration Crew Size – Initial Assessment

14 Moon Exploration Crew Size – Initial Assessment

15 Number of Respondents’ Missions

16 Total Cumulative Mission Times

17 Crew Size of Longest Missions.

18 Crew Size of Largest Crews.

19 Respondent’s crew sizes of long and large missions.

20 Crew Size Opinion #1

21 Crew Size Opinion #2.

22 Free Response Ideal Crew Size

23 Numbers of Ideal Crew Size Free Response

24 Part IV Results

25 Ideal Crew Size

26 Initial and Final Size Comparison

27 Male and Female Variations

28 Gender/Free Response Comparison

29 Military Experience Relationship

30 Military Experience/ Position Selections

31 Aircrew, Missile Crew, and Mars Society Crew Size Inputs

32 Astronaut Crew Size Input

33 Aircrew Crew Size Input

34 Aquanaut Crew Size Input

35 Mars Society Crew Size Input

36 Missileer Crew Size Input

37 Biosphere II Crew Size Input

38 Experience Comparison

39 Seniority Non-Trends

40 Crew Size Averages by Seniority Groups

41 Duration Effects

42 Average by Cumulative Groups

43 Duration Record-Holder Crew Assessments

44 Large Crews for 1+ and 6+ Months

45 Performance Questions

46 Raw Data

47 Keystone Data

48 Mars Mission Tasks

49 NASA’s Crew Exploration Vehicle Concept

CHAPTER I

INTRODUCTION

Background on the Manned Mars Expedition

Humans have sent many missions to Mars, but so far all have been unmanned and semi-autonomous. The results of these missions range from embarrassing failures to resounding achievements. However successful these missions have been, they were all limited in scope and do not compare to actually sending humans to investigate and utilize Mars. So far, the extent of human exploration has been limited to the biomes of the Earth, with minimal exploration on the surface of the moon. But this is all about to change.

On January 14 2004, President George W. Bush implemented a new U.S. Space Exploration Policy. The new policy established a robust space exploration program to advance U.S. scientific, security, and economic interests, but more importantly, the policy concentrated on the importance of extending human presence into space (White House, 2004). This policy directive set in motion the process of re-mobilizing America’s space agencies and related industry with a set of clear, long-term goals. While being clear, the goals are nothing short of monumental: design from scratch the entire manned Mars mission, including new boosters, vehicles, habitats, support systems, structures, logistics and command infrastructure, mission objectives, and a plan to safely accomplish those objectives. The timeline for completion of these goals is to begin launching within twenty years. President Bush provided a much more generous timeline then President Kennedy allowed the Apollo program, but this is not going to be a simple weeklong, 480,000-mile round trip.

There are currently two broad approaches for sending humans to Mars, termed Opposition (or Short Stay) missions and Conjunction (or Long Stay) missions. These missions are based on the interplanetary trajectory between Earth and Mars. Transportation between planets (or any object in space) is governed by the physics of orbital mechanics. Specifically, all transportation is done in an elliptical trajectory – there are no straight shots. So instead of powering one’s way straight to Mars, waiting for the planets to get in position is necessary before launching (similar to timing when to throw a ball to a location where a running person will soon be). After the surface stay, the return mission also has to be timed properly. The two approaches to getting to Mars are based on this timing.

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Figure 1. Opposition Mission Trajectories and Timeline. Note. From NASA presentation Session 6: Human Mars Exploration Mission Architecture and Technologies, by John Connolly and Kent Joosten, 2005, NASA.

Opposition missions are launched so that the Earth upon departure and Mars upon arrival are at opposite sides of the sun in their orbits, and take much less total time than Conjunction missions (approximately 300-day one-way trips, with a surface stay of 40 days). Opposition missions have relatively few supporters, as high velocity changes, known as ÄV (delta-v), are needed to power into Mars’ orbit, subject the crew to substantial acceleration loads. Additionally, the high velocity change require extra thrust, so much of the spacecraft mass is propellant, reducing cargo capacity for food, water, equipment, and crewmembers. Once on the Martian surface, the crew has very little time to accomplish any objectives, especially if repairs are necessary. The majority of the crew’s time will be spent in deep space, necessitating a much more robust interplanetary habitat (and likely limiting the crew size below its optimal number). In addition, the return from Mars involves a Venus swing-by and a very close approach to the sun, exposing the crew to dangerous radiation risks.

Conjunction missions are launched as the planets approach one another approximately every 2 years, and are longer than the Opposition missions (180-day one-way trips and 545 days on the surface). This is generally the more accepted approach. While the total mission time is much longer, the time spent in space transit is cut nearly in half and the shorter trajectories keep a safe distance from the sun, reducing radiation threats. The trajectories themselves require much less ΔV, reducing the amount of necessary propellant and allowing more crewmembers, equipment, and life support mass. A huge benefit of the Conjunction mission is the very long stay on Mars – nearly a full Martian year (almost 2 Earth years). The longer stay allows plenty of time to make repairs, construct a well-established base, conduct surface expeditions and science, and prepare a return craft to get back to Earth. The Conjunction (Long Stay) mission is the most widely supported and will likely be the framework for the first mission to Mars, but the details of that mission plan are still up for debate. Of all the variations, they can be divided into two groups – direct missions and stepped missions.

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Figure 2. Conjunction Mission Trajectories and Timeline. Note. From NASA presentation Session 6: Human Mars Exploration Mission Architecture and Technologies, by John Connolly and Kent Joosten, 2005, NASA.

Dr. Robert Zubrin, a former Lockheed Martin senior engineer and founder of the Mars Society, has developed the standard for direct missions. The plan is called ‘Mars Direct’ (Zubrin, 1996, 3) since missions are launched from Earth directly to Mars, rather than the stepping-stone approach that other plans advocate. Those plans often entail a layover at orbital spaceports or moon bases for constructing and launching large exploration spacecraft or ferries. Mars Direct avoids these stops, reducing costs, limiting up-front capital investment, and simplifying logistics.

The Mars Direct mission plan first sends an unmanned Earth Return Vehicle (ERV) to Mars. Upon arrival, the ERV autonomously begins processing local resources and producing rocket propellants for a later trip to Earth. In the meantime, the first