Mission To Titan | Course Paper

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Ivan Lavlinski

Instructor: Donald Platt

Human Spaceflight

Submitted: 1 December, 2014

Titan Human Space Mission Analysis and Design

INTRODUCTION

Christian Huygens has discovered the tiny moon Saturni Luna, the largest moon of the

Saturn system. However Saturni Luna got its currently known name “Titan” from John Herschel,

who subsequently named all of the known seven Saturn moons. Named after Greek mythology

characters, neither of these great astronomers could predict the real fate of this moon.

Catching up to our time, most of what we know about moon Titan comes from the

satellite and probe Cassini and Huygens, a joint mission that was undertaken by members of ESA

with numerous sensors from countries like USA and Russia. After it’s 7 year journey to Titan,

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Huygens has discovered a moon that has average temperatures of -180 C degrees. This icy moon.

The atmosphere of the moon made of carbon based complex molecules like methane and ethane,

acetylene, and carbon monoxide. Clouds of cyanide were found to be floating amid this

atmosphere of wonder and seas of ethane, methane, and propane lay below surrounded by frozen

rocks made of water ice. Methane rain pours over the vast territories and cyclones at speeds of 20

meters per second form over the vast areas of water of Titan. What is especially astounding is

that, the amount of hydrocarbons that Titan has, exceeds vastly the hydrocarbon resources of

Earth by far. What is more bizarre are the appearing and dissapearing islands composed of

solidifing and evaporating hydrocarbons.

The future of Titan lays with the proposed Titan Mare Explorer that is set to launch in

January 2016. The main goal of Titan Mare Explorer would be to better understand the methane

cycle and also to characterize the depth, chemistry, processes of the Ligeia Mare Lake. The

lander would also study the atmospheric processes above the lake. The utilization of Advanced

Stirling Radioisotope Generator to power this lander at 140 to 160 W of electrical power, the

mass of which would be 28 kg and will have a lifetime of 14 years can be realized if the project

is invested into further. If NASA decided to not go with this proposal than an RTG would be

used instead to power the lander.

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LIFE CYCLE OF HUMAN SPACE MISSION TO TITAN

The design of the human space mission to Titan will follow the Life Cycle implemented

by NASA that is used as a guideline for phases of a crewed space system design. The Life Cycle

would consist of; Advanced Studies, MCR, Preliminary Analysis, MDR, Definition, SRR, SDR,

PDR, Design, CDR, AHP-TOPSIS, Development, SAR, FRR, ORR, Operations, DR. The

success of the mission design to Titan depends on numerous sponsors, operators, customers, and

developers overall coordinated effort.

INCLUSION OF AHP-TOPSIS FRAMEWORK

While generally following the general NASA human space mission life cycle design

scenario, an important aspect that will be utilized is the inclusion of AHP-TOPSIS Framework in

the mission planning would allow to prioritize the analog mission for preparation for the Titan

mission here on Earth. The numerous tests on vehicles both spacecraft, landing, habitat, and

moving, as well as complex surface terrain simulators would require correct prioritizing

assesment which AHP-TOPSIS framework would provide. The framework utilizes subjective

judgements of numerous engineers, scientists, and managers derived from analytic hierarchy

process and orders these preferences into the ideal solution. The basis of prioritizing that will be

used in the mission planning are various phases of the Titan mission which include; Launch

Vehicle, Spacecraft, Titan Landing Vehicle, Titan Roving Vehicle, Titan Transit Vehicle, Titan

Surface Habitat, Titan Surface Terrain. The framework is divided into 3 phases. The first phase is

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where the relevant criteria and sub-criteria and their importance weights are defined through

utilization of mean importance weights for each criteria of the mission and sub-criterias. The

second phase of the framework focuses on the relative priority of the simulators in terms of the

sub-criteria, which produces the revised importance weights of criteria and sub-criteria based on

the intrinsic weights. The third and final step of the framework is the selection of the optimal

simulator, which results in a list of preferences orders of the alternatives.

The importance of incorporation of this framework into the Titan mission planning is

spelled by the long duration of the mission and the overall necessity to conduct numerous

simulations of technology and human performance prior to the mission start.

TITAN MISSION CONCEPT AND ARCHITECTURE

Titan mission concept will consist of six elements; Mission Operations Element, Crew

Element, Orbits and Trajectories, Space Element, Surface Element, Transportation Element.

Mission Operations Element will consist of; Operations Concepts, Operations Functions, Space

Logistics, Command and Control and Communications.

Mission Operations Element

The focus of Mission Operations Element would be to make sure that the mission at Titan

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is going as planned and that all communications as well as control with the DSN network utilized

for communications with Titan relay satellite and subsequent mission update is all going to the

plan. Another goal of Mission Operations Element is the focus on the space logistics and the

underlying science mission completion by the crew of the Titan base, without the inherent

increase in risk and subsequent elements of lowering the danger for the crew and the overall

mission success.

Crew Element

The second part of the Mission Concept is the focus on the Crew themselves. The Crew

element consists of; the astronauts themselves, the operators involved in data and

spacecraft health check, and general MOC crew, physiology of the astronauts and the

MOC crew, human factors involved in long duration spaceflight. At the current fastest

speed to Saturn System by the New Horizons spacecraft flyby maneuver, the trip to Titan

would take an average of two years, thus significant studies on long term physiology and

psychological effects of prolong spaceflight needs to be studied to better assess the needs

of the astronauts in Titan mission. The other part of the Crew Element is the underlying

Safety and Reliability concern involved in this mission. Besides the apparent hazards of

prolonged exposure to dangerous radiation levels during spaceflight, there are apparent

dangers facing the crew during their operation on Titan due to possibility of

depressurization of cabins where they will be staying and exposure to toxic gases such as

cyanide. All of these hazards need to be further reevaluated and an assessment has to be

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made on the protection for the astronauts as well as countermeasures in case of possible

hazard to crew health for both physiological and psychological reasons.

Orbits and Trajectories

The third part of the Mission Concept is the Orbits and Trajectories element, which

consists of; Earth Orbit, Interplanetary direct transfer to Saturn System, Planetary Parking

Orbit, Transfer Orbit to Titan moon, Entry, Descent, Landing, Ascent, Return phases.

Without focusing too much on astrophysics concepts required for the transfer to the

Saturn system, it is apparent that the main strategy of the mission is to reduce the time of

travel to less than two years, so that the crew does not have to face the apparent

psychological and physiological effects of prolonged spaceflight. Another apparent

reasoning behind the direct approach to the Saturn is to save the resources required for

sustaining life support for the astronaut crew on board. Although Huygens descent to

Titan surface was an apparent success, a much different parachute system for a much

larger payload and soft landing needs to be designed in order to answer to the needs of

the human spaceflight mission to Titan.

Space Element

The fourth element in the Mission Concept is the Space Element and it consists of;

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Vehicle configuration, Vehicle for Entry, Vehicle for Descent, Landing, and Ascent,

Subsystems. An apparent major concern of the mission to Titan would be uninterrupted

redundant automated failure proof Life Support System and life support for the crew that

would limit to the minimum the exposure of harmful radiation to the crew. The most

apparent candidates for technology transfer for this mission is the Apollo missions and

ISS Life Support Systems configurations in use currently. The current ISS Life Support

System is called Environmental Control and Life Support System and it provides

numerous functions which include and are not limited to; providing oxygen for metabolic

consumption, provide potable water for consumption, provide food preparation