08-16-2017, 09:14 PM
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ABSTRACT
The purpose of this research is to design an experimental package to be attached to a lunar exploration rover that will demonstrate the feasibility of using lunar regolith as a source for acquiring oxygen in-situ.
The experimental package has two main subdivisions. The robotic arm will be used for excavation of the regolith and delivery to the reaction chambers. The reaction chambers will utilize electrostatic separation and electrolysis techniques to extract oxygen from the soil.
A complete mission timeline will tie all aspects of the experiment operational tasks together, including surface mission phases, scenarios, and necessary procedures for the surface mission including remote and autonomous operations.
Trade studies were performed for the materials to be used for both the reaction chambers and the robotic arm. The factors taken into consideration were based on design methodologies emphasizing low mass, low power consumption, and high efficiency.
Molten Silicate Electrolysis seems to be the most promising method of oxygen extraction. The method under study involves electrostatic separation of the silicates from the soil prior to the molten electrolysis. The electrolysis is to be followed by separation of oxygen from other bi-products of the process and the condensation of pure oxygen in a collection chamber.
The general experimental schematics were developed taking into account the location of the landing site, characteristics of the lunar regolith, and other facets of the lunar environment. A preliminary analysis of the reaction mechanisms was performed for each design option.
With the task definitions and requirements as defined by competition guidelines, a series of trade studies were developed for further study. In the subsequent analyses, power usage, mass, efficiency, and reliability will be optimized.
1. Introduction
We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win, and the others, too. - President John F. Kennedy's Address at Rice University on the Nation's Space Effort, September 12, 1962.
Mankind has long looked to the moon as a source of inspiration. In modern times, our fascination with the moon has pushed us further than human kind has ever gone before; it has inspired the exploration of space. The moon has become our stepping-stone to the universe beyond. This is best exemplified by a re-kindling of the drive to reach the moon that dominated space exploration in the 1960s in the form of the recent push to establish Lunar Stations based upon resources acquired in-situ. In-Situ Resource Utilization (ISRU) studies have become vital to the dream of long term space exploration.
The desire for resources acquired in-situ has arisen out of the need for more cost-effective and sustainable ways of extending man s presence in space. Production of lunar oxygen for life support and fuel in low Earth orbit and beyond is already seen as an economic incentive to build a permanent Lunar base. Current ISRU studies aim at increasing the knowledge of potential resources and mission environments so that such a base may be established in the coming decade. Development of ISRU technologies will increase confidence in their applicability for use in future human missions.
One such ISRU technology is the molten silicate electrolysis method of oxygen extraction. The development of such technology requires acute understanding of the lunar environment and the reaction mechanisms involved. Affordable methods must be developed that minimize mass and power consumption while simultaneously maximizing efficiency.
The premise of this study is to assess the feasibility of implementing molten silicate electrolysis to extract oxygen while meeting these constraints. The experiment is to be carried out aboard a lunar rover that will be launched within the next decade.
2. Assumptions
The following is a list of assumptions made in the design of the Lunar In-Situ Resource Utilization experimental package.
1. The following assumptions are established by the competition guidelines:
A robotic lander will be launched on an expendable launch vehicle early in the next decade and delivered to the south pole region (longitude > 75 ) of the moon.
The lander will carry a rover the size of the Mars Exploration Rovers. The rover will carry the design team s experiment package.
The rover will land in or move into a permanently shadowed crater where water ice is present within a meter of the surface.
The lander has ample volume available to meet experiment requirements.
The typical mass and power constraints of a robotic experiment package are 50kg mass and 100W power.
The rover has near real time communication with the earth.
The experiment shall be designed for a one month surface mission.
2. In addition, the conditions associated with the lunar environment will be assumed as follows:
The composition of the soil is as measured by the Apollo space missions.
The atmospheric pressure of the moon is mbar.
3. The Sensors and remote controllers will adhere to the following assumptions:
The Lunar rover and experimental package will not be affected by environmental damage.
The rover has sensors and controllers which are independent of our experimental package design.
In the event that a sensors or remote controllers should malfunction it will not compromise the entire operation.
4. Other assumptions for the design are as follows:
The operational lifetime of all equipment is longer than the one month test period.
All equipment is undamaged in transit and in landing.
3. Design Methodologies
The methodologies for this experiment have been thoroughly planned and will be used in design implementation. The students working on the project have been divided into subgroups with each subgroup meeting on a weekly basis. General meetings are held every week for the subgroups to report progress.
3.1. Team Subgroups and Weekly Meeting Schedule
The design team has been divided into four subgroups to cover the major aspects of the experiment. The subgroups are Excavation and Delivery Subsystem Design, Concepts of Operations, Analysis, and Public Relations. Each team has weekly meetings in addition to the research team s general meeting.
3.1.1. Subgroups
The task of the Concepts of Operations team is to analyze mission timelines and scenarios. They are also responsible for systems integration within the experimental package.
The task of the Excavation and Delivery team is to design a robotic arm capable of collecting the lunar regolith and delivering it to the reaction chamber. In their design the Excavation and Delivery team will include a drill
The task of the Analysis team to design an oxygen production demonstration utilizing lunar regolith collected from the excavator. The team also manages the design of hardware to remove spent regolith after processing, and sensors and measurements to determine process efficiency as well as an oxygen collection chamber.