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Design of Two Near Term Commercial Space Stations Using Innoslate. Keith A. Taggart, Ph.D. and Steven H. Dam, Ph.D., ESEP. Why Commercial Space Stations?.
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Design of Two Near Term Commercial Space Stations Using Innoslate Keith A. Taggart, Ph.D. and Steven H. Dam, Ph.D., ESEP
Why Commercial Space Stations? • Need to have business case for being in space requires near term value obtainable from activities that can be conducted either only in space or more inexpensively in space • Business cases for space tourism and mining/manufacturing have been made • However, where are people going to visit, work and live? Space stations are one option, but how can we make them affordably?
Two Space Station Concepts Type 2 Type 1 By Keith Taggart
Key Usability Requirements • 35 m radius at 3 rpm gives .35 g • Result of trade between gravity, coriolis force, and size/cost/construction time • Total volume under gravity 3300 m3 or 117,000 cubic feet • Total floor space under gravity about 7200 square feet • One Module is about 300 square feet • A nice hotel room or office or lab • These stations could support: • Research in Long Term Effects of Low Gravity (not micro gravity) Environment • Low Gravity Research in General • Plant Growing in low gravity • Lunar Exploration and Resource Exploitation • Debris Collection • Closed Environment Research • Space Tourism • Space Based Manufacturing • Space Based Power Assembly and Testing • Asteroid Exploration • Research for Radiation Mitigation Techniques • Satellite Repair
Potential Construction Constraints • Modular Construction • 7m long x 5 m diameter modules • 24 to 30 modules Plus • About 35 Falcon Heavy Launches • Roughly One a Month • 40 metric tons per launch to roughly 300km • Modules fit in Falcon Heavy Shroud • Plus – Radial Members, Couplings, Initial Crew Quarters • About 12 Falcon 9 Launches • Construction Crew of 6 Serves for 9 Months • Supply Launch at same time as crew launch • Additional Supply Launch at 4.5 Months • Construction Time About 3 Years • Modules are plug and play • Much assembly work can be done by teleoperation • Operators must be close at hand to avoid latency problems
Module Construction • Module Structure Mass M=(3.1+5.9+4.2+2.0) metric tons • M=15.2 metric tons • Available Launch Mass • M=40 metric tons • Five Layer Shell • Insulation / Impact - Orange • 1cm Mylar and Kevlar Layers, white surface • M=220x.01x1.4=3.1 metric tons • Pressure - Blue • 2x0.5 cm Aluminum • M=2x220x.005x2.7=5.9 metric tons • Sealant - Green • 1 cm Seals small holes • M=220x.01x2.0=4..2 metric tons • Interior - Red • .5 cm Structural Plastic, Foamed Core • M=(220+60)x.005x1.4=2.0 metric tons ~3m Work / Living Hall Down ~2.5m Utilities Utilities ~1.5m Falcon Heavy Provides 160% Launch Margin
“Back of the Envelope” Cost Estimates Launch Costs • 35 Falcon Heavy Launches • 35x40 metric tons=1400 metric tons to about 300 km • 35x120 M$ per launch = 4.200 B$ • 8 Falcon 9 Launches • 4 x 6 Construction Crew • 4 x 10 = 40 Metric tons of supplies • 8 x 56 M$ per launch = .45 B$ • Total Launch Costs to Construct • 4.7 B$ Construction Costs (Much Less Precise) • 30 Modules at 100 M$ each equals 3.0 B$ • Crew Cost • 18 person years x 8760 hours per year x $1000 per hour equals 160 M$ • Equipment and Supply Cost 200 M$ • Ground Support 200 M$ • Fudge Factor 400 M$ • Total Construction Cost about 4.0 B$ Total Costs About 9 B$
Operating Cost Issues • Supplies and Trash Removal • 10 Permanent Residents • 10 Visitors • Food • Assume 3000 calories per day per person • Assume 3 calories per gram • One kilogram of food per person per day • Multiply by 2 for “packaging” gives about 15 metric tons per year • Roughly the same amount of waste needs to be returned to earth • Supplies, including food, water, and other consumables could be handled with weekly or bi-weekly visitor transport on Reusable Falcon 9 launches
Operating Cost Issues (continued) • Recycle versus Renew • 4.3 Metric Tons of Atmosphere • 5 Metric Tons of Reserve in Pressurized Storage • 1% loss per week • About 5 Metric Tons Replacement per year • Water • 40 gallons per person per day • 0.15 cubic meters • 20 people need 3 cubic meters or 3 metric tons per day • Assume a week to recycle the water with 1% loss • Requires 21 cubic meters of water stored • Plus 0 .21 cubic meters replacement per week or • About 12 metric tons per year • If Recycle Efficiency Falls below 95% per week then replacement cost could become problematic.
Difficulties / Opportunities • Power • Radiation Protection • Orbital Debris • Collision Protection • Collision Avoidance • Station Dynamics and Control • Orbital Change of a Spinning Station • Attitude Control • Spin Control • Recycling • Atmosphere • Water • Waste • Economic Viability • Liability / Insurance “A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty.” Winston Churchill
Applying MBSE • To take this design to the next stage, a number of systems engineering trade studies needs to be applied to this initial architecture • Creating system models of this architecture will support the trade studies and enable more detailed design work • We begin by identifying the requirements embedded in the design
Discrete Event Simulation • Execution of model provides timing, resources and costs
Cost Profile from DES Cost (M$)
Other Analyses • As the work progresses, we can capture risks, key decisions, related artifacts (e.g., standards, regulations), metrics, results of high-fidelity simulations, V&V activities, and anything else associated with the design • By providing all this in a collaborative environment (via private or public cloud computing) we can bring large teams together
Summary • We have just begun to explore the utility of commercial space stations • Applying MBSE techniques during the architecture phase enables more robust trade-offs • Having a scalable, integrated tool cuts time, and therefore costs, that can then be applied to great quality and profitability