A program is underway to develop a YAG laser based materials processing workstation to fly in the cargo bay of the Space Shuttle. This workstation, called Space Applications Industrial Laser System (SAILS), will be capable of cutting and welding steel, aluminum, and Inconel alloys of the type planned for use in constructing the Space Station Freedom. As well as demonstrating the ability of a YAG laser to perform remote (fiber-optic delivered) repair and fabrication operations in space, fundamental data will be collected on these interactions for comparison with terrestrial data and models. The flight system, scheduled to fly in 1996, will be constructed as three modules using standard Get-Away-Special (GAS) canisters. The first module holds the laser head and cooling system, while the second contains a high peak power electrical supply. The third module houses the materials processing workstation and the command and data acquisition subsystems. The laser head and workstation cansisters are linked by a fiber-optic cable to transmit the laser light. The team assembled to carry out this project includes Lumonics Industrial Products (laser), Tennessee Technological University (structural analysis and fabrication), Auburn University Center for Space Power (electrical engineering), University of Waterloo (low-g laser process consulting), and CSTAR/UTSI (data acquisition, control, software, integration, experiment design). This report describes the SAILS program and highlights recent activities undertaken at CSTAR

Bible, J. B.

Mccay, T. D.

Mueller, R. E.

English

NASA Technical Reports Server

,s 153 
Space Applications Industrial Laser System (SAILS)' - 
The University of Tennessee-Calspan 
Center for Space Transportation and Applied Research (CSTAR) 
Tullahama, TN 37388-8897 
and 
The University of Tennessee Space Institute (aSI) 
Center for Laser Applications 
Tullahama, TN 37388-8897 
ABSTRACT 
A progra is under way to develop a YAG laser based materials processing 
workstation to fly in the cargo bay of the Space Shuttle. This 
workstation, called Space Applications Industrial Laser System (SAILS), 
will be capable of cutting and welding steel, aluminum and Inconel 
allays of the type planned for use in constructing the Space Station 
Freedom. As well as demonstrating the ability of a YAG laser to perfom 
remote (fiber-optic delivered) repair and fabrication operations in 
space, fundamental data will be collected on these interactions for 
comparison with terrestrial data and models. 
The flight system, scheduled to fly in 1996, will be constructed as 
three modules using standard Get-Away-Special (GAS) canisters. The 
first module holds the laser head and cooling system, wfiile the second 
contains a high peak power electrical supply. The third module houses 
the materials processing workstation and the cammand and data 
acquisition subsystems. The laser head and workstation canisters are 
linked by a fiber-optic cable to transmit the laser light. 
The team assembled to carry out this project includes Luronics 
Industrial Products (laser), Tennessee Technological University 
(structural analysis and fabrication), Auburn University Center for 
Space Power (electrical engineering), university of Waterloo (lw-g 
laser process consulting), and CS!T!AR/uTsI (data acquisition, control, 
software, integration, experiment design). 
This report describes the SAILS program and highlights recent activities 
undertaken at CSTAR. 
INTRODUCTION 
The UT-Calspan Center for Space Transportation and Applied Research 
(CSTAR) is one of 17 NASA Centers for the C-cia1 Developrent of 
Space (CCDS). The mission of CSTAR is to team with industry and 
academia in the development of new and innovation space technologies. 
'This work is supported by NASA Code C under grant NAGW-1195, The 
University of Tennessee Space Institute, Lumonics Industrial Products 
Division. 
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The SAILS program has been developed under this mission because of its 
broad potential to benefit industry, academia, and government through 
advanced laser materials processing technology. 
The project team consists of five organizations, headed by Professors 
Dwayne and Mary Helen McCay of CSTAR and the -1 Center for Laser 
Applications, Professor Walt Duley of the University of Waterloo, Steve 
Llewellyn of Lumonics Corporation, Professor Richard Houghton of 
Tennessee Technological University, and Professor Ray Askew of Auburn 
University. Brice Bible of CSTAR is the program manager and Susan Olden 
of the Goddard Space Flight Center (GSFC) is the mission manager. 
The long term space missions planned by NASA will require some fora of 
machining and repair capability. !Fhe SAILS experhnt will act as the 
proof -of -concept to firmly establish the YAG laser as a viable materials 
processing tool for space applications . Follow on phases to the program 
will develop the infrastructure necessary for implementation on long 
term space structures by the end of the century. 
i 
I As the lifetime and complexity of space structures increase, our ability 
to construct, maintain and repair these structures in space must also be 
improved. The industrial laser represents a possible solution to the 
problem of conducting multiple task manufacturing and repair operations 
I at remote, hostile locations such as an orbiting platform, 
The purpose of the SAILS project is to demonstrate the capability to 
employ a YAG laser processing facility in space and to perform practical 
laser materials processing operations under microgravity conditions. 
The objectives of this project may be grouped under the following 
I categories: 
Science: Determine the effects of gravity on welding, drilling, cutting, 
brazing, and soldering. Compare experimental results with models to 
improve predictions of process behavior in 1 and 0 g. 
Space Enqineerinq: Demonstrate the viability of laser technology to 
perform repair and fabrication type operations in space- Applications 
include a laser repair kit for Space Station, manned Mars missions, a 
noon base, and a laser-based factory in space. 
Laser Enqineerinq: Design refinement anddemonstration of the industrial 
YAG laser to show that it has become a simple, compact, efficient and 
rugged tool capable of operating in any environment. It is of 
particular importance to show the advantages of fiber optic b e a m  
delivery, including ruggedness and the ability to operate in remote and 
harsh environments. 
The 1996 flight, designated SAILS-01, is the first in a series of 
experiments designed to validate the YAG laser as a viable multipurpose 
energy workstation for space. Interest by the NASA Code C CCDS 
community as well as other industry, academia, and government 
organizations has resulted in plans for at least two follow-on flights. 
Figure 1 indicates the current flight strategy for the SAILS facility. 
88 
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2ooo 
Auburn 
Flight 
sAILs-02 S p m b s e d  
I STS Laser Workshtion Program STS Flight ' 
NASA 
SAILS Flight Apptovd SAILS4 
Started Flight 
CoaHng 
Flight 
1 Spot/Seam Weld 
J 
Figure 1 SAILS Facility Flight Plans 
Drill/Cut Braze Solder 
J J 
SAILS EXPERIMENT SELECTION 
As the BAILS experiment is designed to demonstrate the viability and 
practicality of laser materials processing in space, the processes to be 
tested and the materials used should have some application in space 
systems. After initial trials to show that the materials could be 
processed with the laser power anticipated for the flight system, the 
materials and processes were selected as shown in Table 1. 
J 
J 
Table 1. Materials and Processes Selected for Testina in the SAILS 
J 
J 
Experiment. 
Material 
316L Stainless 
2219 Aluminum 
6061 Aluminum 
Inconel 718 
Copper 
Kapton 
Lead/Tin J I 
I I I 
d I J I I 
I I 1 
J 
J 
The processes all have obvious practical applications, in space or on 
earth. Btructural joining operations (welding and brazing) will be 
needed in the assembly and repair of man-rated habitats. Cutting will be 
required for removing damaged components for repair and in the recycling 
of space debris. Soldering of electrical and electronic components could 
be accomplished remotely using a dexterous manipulator and a fiber 
delivered laser beam, with much less heat input to nearby components 
than with a conventional solder iron. 
89 
GROUND EXPERIMENTATION 
Preliminary studies were carried out during 1991-92 using a 400 W 
Lumonics JK701 YAG laser to show that the materials and processes under 
consideration could be processed with a relatively low power laser. 
Since that time, the operating characteristics of the flight laser have 
been made available with the introduction of the LUXSTAR laser by 
Lumonics Corporation, the industrial sponsor for the program (see Table 
2). Detailed experiment studies will be completed in late 1993 at CSTAR 
using the LUXSTAR laser to produce the precise processing conditions 
anticipated for each of the flight experiment samples. As well as 
finding workable combinations of processing parameters, this study will 
determine scaling relationships (depth and width of weld vs power, metal 
structure) between the flight power level and presently available 
ground-based laser power levels. This will allow us to predict the 
performance of higher power lasers operating under space conditions. 
Average power 
Peak optical power 
Pulse length 
Pulsinq rate 
50 W 
3000 W 
0.5 - 20 ms 
to 100 Hz 
Pulse energy 
Fiber core diameter 
to 30 J [lo J] 
400 um 
Minimum spot sire 
Dimensions (Industrial unit) 
200 pm 
86.5~56.5~77.5 cm 
FLIGHT HARDWARE DESIGN 
The SAILS flight experiment will be housed in three Get-Away-Special 
(GAS) canisters mounted on the HitchEiker cross bay carrier. These 
canisters will be interconnected via the top plates for experiment 
control and distribution of power and laser energy. Figure 1 shows this 
three-canister configuration and the major components in each module. 
Weight (Industrial unit) 
Input voltage 
Output voltage to Flashlamp 
Power Consumption 
The first canister, CAN 1, will contain the laser head, output module 
(capacitor bank), and cooling system for generation of the laser energy 
necessary to conduct the experiments. The laser head and output module 
will be acquired and repackaged from the LUXSTAR Nd:YAG 50 W laser 
system, a new commercial product manufactured by Lumonics. The cooling 
system, consisting of a pump and heat exchanger, will be fabricated at 
CSTAR to provide transfer of the heat generated in the laser cavity 
200 kg 
200-240 VAC 128 VDC] 
660 V pulses 
5.5 kW 
90 
during processing. 
The second canister, CAN 2, contains the electrical power supply for 
providing the high peak power necessary to generate the laser energy in 
CAN 1. This can will consist of Silver-Zinc battery cells housed in a 
vented container (power source), a DC-DC convertor for electrical power 
conditioning, and the laser control module. The DC-DC convertor will 
condition the battery energy to the proper voltage for transfer to the 
capacitors in CAN 1. The Auburn University Center for Space Power will 
design and fabricate the power conditioning system in this canister and 
the power source will be provided by CSTAR. Use of orbiter power was 
considered as an alternative to the batteries for laser power. However, 
the peak power requirements for the experiment is approximately 5 kW, 
which is greater than the maximum of 3.5 kW available to a HitchEiker 
customer . 
CAN 1 and CAN 2 will be connected via an electrical cable for transfer 
of the high voltage battery power from the power supply to the laser 
head. The connectors, cable support structure, and canister modifi- 
cations will be provided by GSFC and are currently under development. 
CSTAR will provide the electrical cable. 
The combination of CAN I, CAN 2, and the voltage interconnection produce 
a complete, self-contained, ruggedized NdtYAG laser system for delivery 
of laser energy to the experiment workstation, CAN 3. 
The third canister, CAN 3, contains the workstation for conducting the 
SAILS experiments. This canister consists of the experiment samples, 
workhandling, and command and data acquisition systems. The sixteen 
samples (2.5 cm X 5.5 cm each) will be rotated on a platen and located 
under the laser beam for processing. A given sample will be processed 
for approximately 15 seconds, followed by a monitoring period to allow 
each critical subsystem to return to the appropriate operating 
conditions before moving to the next sample. This will continue until 
all 16 samples have been processed. The internal laser beam will be 
delivered as a free-space beam with moving optics. This configuration 
mimics current industrial laser practice of using a moving optics end 
effector to achieve more motion flexibility. The data acquisition 
systems will include video storage of the actual process (coaxially and 
along the sample), recording of the environmental conditions before and 
during each process, and monitoring of the laser process parameters 
(pulse length, energy, and duration) for each sample. 
CAN 3 will be linked to CAN 1 via a fiberoptic cable for delivery of the 
laser energy to the workstation. This cable will consist of a 400 
micron fiber surrounded by a copper shield and control/continuity data 
lines all encompassed in a nylon outer cover. The connectors will be 
designed for a hermetic seal at the canister with lid modifications to 
be provided by GSFC and the fiber/connectors to be provided by CSTAR. 
Each of the three canisters will be filled with Argon gas pressurized to 
one atmosphere and filled with inert gas. CAN 1 and CAN 2 will use dry 
N2 while CAN 3 will use Argon to provide enhanced processing conditions 
for the flight hardware components. 
91 
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92 
PROGRESS TO DATS 
The SAILS program was proposed to NASA Code C in 1990 with funding and 
payload approval received in 1991. As described above, work through 
PY92 focussed primarily on establishing the operating envelope necessary 
to accomplish the experiment objectives of the program. FY93 has 
centered on design and development of the flight hardware required to 
accomplish these objectives. To date, the following activities either 
have been completed or are underway: 
Completion of preliminary design of the components in each of 
the three canisters, including the interconnecting fiberoptic 
and electrical systems. 
Candidate hardware systems for many of the components in the 
sample workstation canister, CAN 3, have been identified and 
several components have been procured. The computer/control, 
VCR, and camera systems have been purchased and are currently 
under development and integration at CSTAR. TTU has COmpl8ted 
preliminary design of the internal experiment structure and a 
prototype test frame has been fabricated for vibrational 
testing. 
The Lumonics LUXSTAR laser, CAN 1, has been installed at CSTAR 
and is currently undergoing operations testing. A prototype 
cooling system has been developed and will be tested with the 
laser in early FY94. 
The electrical and fiberoptic interconnection systems have 
been discussed with GSFC. Design and fabrication of the 
external mounting hardware will be provided by GSPC and 
development of the cables will be provided by CSTAR. 
The Carrier Payload Requirements (CPR) document has been 
submitted to the GSFC Small Payloads Office with final 
approval anticipated by September 1993. The Safety Data 
Package has been initiated with the potential hazards 
identified in the Payload Safety Requirements Matrix. 
Submittal of the package to JSC for the Phase 0/1 safety 
review is expected shortly after the CPR is approved. 
pY94 ACTIVITIES 
Activities in FY94 will focus on continued development of the flight 
hardware with completion of procurement and fabrication of the sample 
workstation canister (CAN 3) modules and most of the laser (CAN 1) and 
power (CAN 2) canister components anticipated. Some of the major 
milestones planned for BY94 include: 
Procurement/fabrication of the experiment motion system, 
internal optics, sample carrier, and internal frame for CAN 3 
will be completed. Integration and testing of the canister 
will be initiated. 
Development of the power supply, cooling system, batteries, 
and internal frames for CAN 1 and CAN 2 as well as integration 
of these modules into the LUXSTAR laser for operational tests 
will be initiated. 
Design of the fiber, voltage, and control interconnects will 
be comple+.ed and fabrication will be initiated. 
93 
. 
Identification of the payload safety-critical items and safety 
verification procedures will be completed. The Phase 0/1 
safety review will be completed and the Phase 2 review process 
will be initiated. 
The SAILS Program Schedule is shown on Figure 3 and illustrates the 
overall timetable planned to achieve the FY96 shuttle flight. 
CONCLUSION 
A program is well underway to develop the first laser materials 
processing workstation for use in space. As well as providing 
fundamental information on several laser-material interactions, this 
program will demonstrate the ability of laser processing to perform 
useful repair and fabrication operations in space. 
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