Currently there is considerable interest in developing in-situ materials processing plants for both the Moon and Mars. Two of the most important aspects of developing such a materials processing plant is the overall system design and the integration of the different technologies into a reliable, lightweight, and cost-effective unit. The concept of an autonomous materials processing plant that is capable of producing useful substances from lunar regolith was developed. In order for such a materials processing plant to be considered as a viable option, it must be totally self-contained, able to operate autonomously, cost effective, light weight, and fault tolerant. In order to assess the impact of different technologies on the overall systems design and integration, a one-half scale model was constructed that is capable of scooping up (or digging) lunar soil, transferring the soil to a solar furnace, heating the soil in the furnace to liberate the gasses, and transferring the spent soil to a 'tile' processing center. All aspects of the control system are handled by a 386 class PC via D/A, A/D, and DSP (Digital Signal Processor) control cards

Goettsch, Ulix

Ousterhout, Karl

English

NASA Technical Reports Server

Development of : Material
Processing Plant for Lunar Soil
Ulix Goettsch and Karl Ousterhout
-, 6N 76 9
7
Department of Aerospace and Mechanical Engineering
The University of Arizona
Abstract
Currently there is considerable interest in developing in-situ materials processing plants for both the
Moon and Mars. Two of the most important aspects of developing such a materials processing plant
Is the overall system design and the integration of the different technologies into a reliable,
lightweight, and cost-effective unit. This paper develops the concept of an autonomous materials
processing plant that is capable of producing useful substances from lunar regolith.
In order for such a materials processing plant to be considered as a viable option, it must be totally
self-contained, able to operate autonomously, cost effective, light weight, and fault tolerant. In order
to assess the Impact of different technologies on the overall systems design and integration, a
one-half scale model has been constructed that is capable of scooping up (or digging) lunar soil,
transferring the soil to a solar furnace, heating the soil In the furnace to liberate the gasses, and
transferring the spent soil to a "tile"processing center. All aspects of the control system are handled
by a 386 class PC via D/A, A/D, and DSP (Digital Signal Processor) control cards.
IV-21
https://ntrs.nasa.gov/search.jsp?R=19930017505 2020-03-17T05:38:03+00:00Z

I. Introduction
The Artemis program, initiated by NASA, is geared toward the development of a Common Lunar
Lander (CLL) that will serve as a platform for a wide variety of robotic exploration missions to the
lunar surface. The CLL is envisioned as a small lander which is capable of being launched from an
existing launch vehicle and that will carry an autonomous payload for performing a variety of
experiments. Currently, planned payloads Include Insitumaterials utilization (ISMU) experiments and
astronomical observatories. NASA is conducting work in two separate but interrelated areas: the
development of the Artemis Lander and the Artemis Lander's payloads. This paper discusses
preliminary research underway at The University of Arizona's Space Engineering Research Center
to design and build a one-half scale autonomous oxygen production facility for inclusion in the
Artemis program.
II. Mission and Task Reauirements
The mission requirements for the autonomous oxygen production facility are straight forward: the
plant must be capable of autonomous oxygen production for a period of 35 to 365 days, the
payload may have a maximum mass of 65 Kg (143 Ibf), the payload must fit within the envelope
illustrated in Figure 1, and the payload must operate from a platform as illustrated in Figure 2.
Additionally, the four main tasks for the autonomous oxygen production facility can be decomposed
as shown below in Table 1:
IV-22
1) Soil sample acquisition:
• Move pdmary arm and gather soil.
• Sift soil to remove large Impurities.
• Transfer sifted soil to crucibles.
• Transfer crucible from rack to reactor with secondary arm.
2) Reactor operation:
• Mix solid carbon powder with soil.
• Insert crucible at the focal point.
• Control heating temperature.
• Measure and identify gasses.
• Remove residue and reprocess to make tiles.
3) Data Management
• Obtain measurements and store data.
4) Telemetry
• Adjust antenna and either transmit to Earth or receive data
from Earth.
Table 1. Miss/on requ/rements for the autonomous oxygen production facility.
The autonomous oxygen production facility combines two related experiments into one payload.
The first experiment, lunar oxygen production, will serve to demonstrate the feasibility of using solar
energy to reduce lunar soil and release the oxygen which is bound within the ilmenite (chemically
known as iron titanate, FeTiO3). The second experiment, lunar brick production, will demonstrate
the feasibility of making "lunar bricks" from the previously processed lunar soil. At the completion
of the "lunar brick" production process, the lunar soil will be in a hardened brick-like form suitable
for building lunar structures.
III. Payload Desian, Layout, and Ooeration
In order for the autonomous oxygen production facility to F_the mission requirements, the current
design allows for the four main components - the primary mirror, the secondary mirror, the primary
arm, and the secondary arm - to be stowed in the configuration shown in Figure 3 for space flight.
IV-23
Once the CLL has landed on the Moon, the primary mirror, the secondary mirror, and the pdmary
arm will deploy and operate as illustrated in Figures 4 and 5. The individual components of the
autonomous oxygen production facility are illustrated in Figure 6.
The turntable and pallet contain the mounting interface to the lander itself. The turntable is the
foundation upon which all of the other components of the payload (except the pallet) are mounted.
Additionally, the turntable allows for 360 degree rotation of the payload for soil collection, solar
tracking, and telemetry. The pallet, which is fixed to the lander and does not rotate with the
turntable, Is used for storage of the crucibles which will be filled with collected soil for processing.
It accommodates both small crucibles (10 g capacity) for oxygen production and large crucibles
(50 g capacity) for glass production.
The primary arm is used to collect"soil and deposit it into a sieve mechanism which returns large
soil particles (rocks) to the lunar surface and fills the crucibles with the fine soil. The arm is a four
degree-of-freedom (waist, shoulder, elbow, and wrist) robot with a scoop for soil collection. Besides
the waist joint (the turntable), all of the motors are contained in a drive assembly located at the
shoulder joint. Torque istransmitted through gear/chain and pulley/cable combinations and position
feedback is obtained through the use of optical encoders located at each of the joints. Since the
payload must be autonomous, the arm is Instrumentedwith strain gauges to provide force feedback
along three orthogonal axis. This will Inform the controller in the event that the arm contacts
Immovable obstacles such as large surface or subsurface rocks.
Once the lunar soil is placed in the hopper by the scoop attached to the primary arm, it is then
processed through a sieve consisting of a series of screens with decreasing mesh size. Particles
that are too large for production purposes are allowed to exit the sifter at each stage where they
are allowed to return to the lunar surface. The fine soil that passes through the sieve is collected
in a hopper where it can then be poured into a crucible. This last step is accomplished by rotating
the turntable until one of the empty crucibles is positioned directly below the spout of the hopper.
After one of the crucibles has been loaded with lunar soil, the turntable is rotated to a position
where the secondary arm can pick up the crucible and transfer it to the furnace for either oxygen
or glass production.
When producing oxygen, the secondary arm positions the crucible under the transparent furnace
lens and against a seal which traps the evolved gas. Solar energy collected by the mirrors focuses
IV-24
on the soil sample and heats it to the proper temperature for oxygen generation. Once the oxygen
production process Is completed, the secondary arm returns the crucible along with the spent
sample to the pallet. When producing lunar bdcks, the large crucible Is positioned just above the
furnace, where the nearly focused beam hits the soil sample. Gases evolving during the melting
process are allowed to escape to the lunar atmosphere. Once the soil sample is molten, the
secondary arm positions the crucible over one of molds and pours the molten soil into it. Once the
glass sample has cooled, the secondary arm moves it to the materials testing unit where it is ejected
from the mold and its mechanical properties are determined.
The solar energy needed to process the lunar soil is collected and focused onto the furnace via a
primary and secondary mirror system. The two meter diameter parabolic primary mirror Is mounted
on a cart which rides a circular arc to follow the sun vertically above the horizon and the turntable
rotates to follow the sun horizontally across the horizon. The convex secondary mirror is located
at the center of the circuiar arc to maintain a constant focal length. The secondary mirror directs
the collected solar energy downward into the furnace, elongating the beam so that the focal point
is Inside the furnace. A tracking system, consisting of a two by two solar panel array, is used to
track the sun throughout the lunar day. All of the power to operate the robotics, analytical
equipment, computers, and telemetry is provided by solar panels which deploy from the rear of the
primary mirror. This mounting configuration insures that the solar panels are always optimally
positioned with respect to the sun. The only time that the solar panels are not tracking the sun is
when either the primary arm Is collecting soil or the secondary arm Is selecting a crucible from the
pallet. When these operations are taking place, power is supplied by batteries.
IV. Controls and Electronics
As mentioned previously, all aspects of the control system are handled by a 386 class PC via D/A,
A/D, and DSP (Digital Signal Processor) control cards. This hierarchical control system allows for
the 386 class PC to act in supervisory mode while the individual motions of each of the axis of
_ . _-_ _-_7_ -_- -_--- _----: - - ;- _.._---_-_ ....
movement are controlled via the DSP control cards. Thus, the PC is able to process data taken
during experiments or run diagnostics while the manufacturing process is underway.
Although the PC is capable of transmitting data to a mother craft or Earth during the lunar day, a
rechargeabie battery wili _ included within the system so that data reduction and communications
IV-25
can be conducted during the lunar night. During the lunar day, the photovoltaic cells mounted to
the rear of the primary mirror will recharge the battery. The electrical power requirements and the
masses of the Individual components are shown below In Table 2.
Power (w) Mass (kg)
Communications 10/120 3.5
Computer 16 4.25
Sensors/Actuators
Servo motors (8) 480.0 6.4
Row meters (2) 7.5 0.8
Pressure sensors sensors (2) 0.2
Force/torque sensors (2) *
Proximity sensors; strain gauges
Flow control valves 2.4 1.2
Thermocouples (2) * *
CCD Camera (1) 3.0 0.2
Mass Spectrometer (1) 2.0 0.5
Total 495.1 10.2
*Negligible
Table 2. Power and mass breakdown.
0.1
Conclusion
The technologies developed over the last fouryears at The University of Arizona NASA Space
Engineering Research Center are being integrated into the design of the Common Lunar Lander.
At this time, a one-half scale model has been constructed and testing is currently underway.
Although the current design of the autonomous materials production facility is highly automated,
the main focus of this research is to integrate the necessary technologies in such a manner that the
completed design is highly reliable and fault tolerant.
References
Taylor, I. Common lunar lander. Artemis Workshop, February 3-5, 1992.
Ramohalll, K., K. Ousterhout, K.R. $ridhar, and J.M. DiFrancesco. A robotic common lunar lander
concept in support of the space exploration initiative.Accepted for presentation at the ASME winter
Annual Meeting, Anaheim, California, 1992.
IV-26
122 cm I
(48 in)
i
254 cm diameter
(100 in)
! 61 cm(24 in)
lb..=
Figure 1. Approximate CLL Payload Dimensions.
I_..,= 254 cm diametel
I _ (100 in)
I
J__
400 cm diametel
057 in)
I
146 cm
(58 in )
Figure 2. Approximate CLL Dimensions.
Z
=
=_
Figure 3. The CLL As Landed - In An Undeployed State.
IV-27
Secondary Mirror
A
Primary Mirr_
I !
Figure 4. Primary and Secondary Mirrors Deploying.
236 cm ](93 in)
74 cm
(29 in)
173 cm
(68 in) (68 in) v I
Figure 5. Primary Arm Operating Range.
IV-28
Pr Mirror
Secondar_
Turntable
Sifter
•,_ Solar Panels
Furnace
Telescoping Arm
For Secondary
Mirror
Secondary
Mirror
crucibles
PrimaryArm
Figure 6.
Scoop
Top View of The Robotic Oxygen Production Facility.
IV-29


Development of a material processing plant for lunar soil

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server