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Dr. Jones Analysis:

Feasibility Analysis of Human Tended Space Solar Manufacturing Facility

August 2012

Reference: US Patent 7,971,831 Roseman  July 5, 2011  This paper is a rough order of magnitude (ROM) analysis of the capability of the Delta IV Super Heavy using 6 CBCs (First stage CBC plus five strap-on CBCs) to place a Solar Manufacturing facility into orbit around the Earth. This analysis was done by Mr. Royce Jones for Mr. Paul Roseman.

Abstract
Mr. Paul Roseman has patented a concept for the manufacturing of solar panels in space. His patent is based on getting the Delta IV first stage and two CBC boosters into LEO orbit for re-use. "I need an analysis of the Delta-IV boosters, because they are LOX boosters, (people will be living inside of them) and there are 3 of them.  I need 12 of them for the construction of the variable gravity by rotation manufacturing facility in LEO."

"For the first analysis, the goal is to get a full set of the 3 boosters in the Delta-IV into LEO, using 3 additional Delta-IV boosters at full power that drop off. There are 2 different upper stages used with the Delta-IV, the first analysis should start with the smaller upper stage (not the additional main booster).  That upper stage is not fueled, so goes empty of fuel into LEO, with the 3 main boosters, and the payload." From this it is taken that the new vehicle (which will be referred to as the Delta IV Super Heavy (SH)) will use a core first stage and five boosters. Boeing has proposed a Five CBC and Seven CBC version of the Delta IV Heavy. Using a Six CBC solution would fit between these two proposed upgrades. Placing 12 CBC units into orbit three at a time would require four launches.

"The empty rocket CDC rocket stages and empty upper stage would be placed in the low orbit, 185 miles high using the Kennedy orbital inclination. I hope that they can get there, and I want to know the payload that can be brought with them."

Background

Delta IV launch vehicles can accommodate single or multiple payloads on the same mission. The rockets can launch payloads to polar orbits, sun-synchronous orbits, geosynchronous and geosynchronous transfer orbits (GTO), and low Earth orbit (LEO). Delta IV is an active expendable launch system in the Delta rocket family. Delta IV uses rockets designed by Boeing's Integrated Defense Systems division and built in the United Launch Alliance (ULA) facility in Decatur, Alabama. Final assembly is completed at the launch site by ULA. The rockets were designed to launch payloads into orbit for the United States Air Force Evolved Expendable Launch Vehicle (EELV) program and commercial satellite business. Delta IV rockets are available in five versions: Medium, Medium+ (4,2), Medium+ (5,2),Medium+ (5,4), and Heavy, which are tailored to suit specific payload size and weight ranges. Delta IV was primarily designed to satisfy the needs of the U.S. military. Comparable rockets are Atlas V, Ariane 5, Chang Zheng, Angara, H-IIB, Proton, Falcon 9, and Falcon Heavy

The rockets are assembled at the Horizontal Integration Facility for launches from SLC-37B at Cape Canaveral, and in a similar facility for launches from SLC-6 at Vandenberg AFB.

The Delta IV entered the space launch market at a period when global capacity was already much higher than demand. Furthermore, as an unproven design it has had difficulty finding a market in commercial launches, and the cost to launch a Delta IV is somewhat higher than that for competing vehicles. In 2003, Boeing pulled the Delta IV from the commercial market, citing low demand and high costs. All but one of the first Delta IV launches have been paid for by the U.S. Government, with a cost of between $140 million and $170 million. The Delta IV Heavy has a price of approximately $250 million per flight.Dividing the cost per CBC stage by 3 and then adding three additional CBC Boosters would give a rough cost estimate of $ 500 million per flight for a Delta IV Super Heavy launch vehicle. This is about half the cost of launching a Space Shuttle.

Delta IV is built around the 5.1 meter diameter Common Booster Core (CBC) first stage powered by a single 300 metric ton thrust Rocketdyne RS-68. The liquid hydrogen (LH2) and liquid oxygen (LOX) engine is the world's most powerful cryogenic engine and is the first new big liquid propellant rocket engine developed in the U.S. in more than 20 years.

Two Delta IV LOX/LH2 second stages are available. The first is a stretched Delta III second stage with a 4 meter diameter forward LH2 tank. The second has a 5.1 meter diameter LH2 tank. Both use a 3 meter LOX tank suspended beneath the LH2 tank by an intertank truss. Mitsubishi Heavy Industries of Japan builds the LH2 tanks.

Both second stages are powered by a single Pratt and Whitney RL10B-2 engine. The engine has a French-built extendable exit cone, is restartable, and is capable of producing 11.23 tons of thrust. At one point, Mitsubishi and Boeing were jointly developing a new, more powerful engine, based on H-2A technology, that might eventually replace RL10, but this effort was apparently shelved after Boeing sold Rocketdyne to Pratt & Whitney in 2005.

The first Vandenberg AFB Delta 4 launch took place on June 28, 2006 when a Delta IVM+(4,2) placed NRO L-22, a National Recconnaisance Office payload, into an elliptical 12 hour Molniya orbit.

Launch facilities

Delta IV launches occur from either of two rocket launch sites. On the East coast of the United States, Space Launch Complex 37 (SLC-37) at the Cape Canaveral Air Force Station. On the West coast, polar-orbit and high-inclination launches use Vandenberg Air Force Base's Space Launch Complex 6 (SLC-6) pad.

Launch facilities at both sites are similar. At the pad is a Mobile Service Tower (MST), which provides service access to the rocket and protection from the weather. There is a crane at the top of the MST, which allows the payload and GEM-60 solid motors to be attached to the vehicle. The MST is rolled away from the rocket several hours before launch. At Vandenberg, the launch pad also has a Mobile Assembly Shelter (MAS), which completely encloses the vehicle; at CCAFS, the vehicle is partly exposed near its bottom.

Beside the vehicle is a Fixed Umbilical Tower (FUT), which has two (VAFB) or three (CCAFS) swing arms. These arms carry electrical, hydraulic, environmental control, and other support functions to the vehicle through umbilical lines. The swing arms retract at T-0 seconds to prevent them from hitting the vehicle.

Under the vehicle is a Launch Table, with six Tail Service Masts (TSMs), two for each CBC. The Launch Table supports the vehicle on the pad, and the TSMs provide further support and fueling functions for the CBCs. The vehicle is mounted to the Launch Table by a Launch Mate Unit (LMU), which is attached to the vehicle by bolts that sever at launch. Behind the Launch Table is a Fixed Pad Erector (FPE), which uses two long-stroke hydraulic pistons to raise the vehicle to the vertical position after being rolled to the pad from the Horizontal Integration Facility (HIF). Beneath the Launch Table is a flame duct, which deflects the rocket's exhaust away from the rocket or facilities.

The Horizontal Integration Facility (HIF) is situated some distance from the pad. It is a large building that allows the Delta IV CBCs and second stages to be mated and tested before they are moved to the pad. The horizontal rocket assembly of the Delta IV are similar to the ones with the assembly of Soyuz launch vehicles; they are also assembled horizontally, unlike the current Space Shuttles, the past Saturn launch vehicles and the upcoming Ares I and Ares V, where they are assembled and rolled out to the launch pad entirely vertically.

Movement of the Delta IVs among the various facilities at the pad is facilitated by Elevating Platform Transporters (EPTs). These rubber-tired vehicles can be powered by either diesel engines or electric power. Diesel EPTs are used for moving the vehicles from the HIF to the pad, while electric EPTs are used in the HIF, where precision of movement is important.

Vehicle processing

Delta IV 4-Meter Second StageThe Delta IVs are assembled using a process that Boeing claims reduces cost and expensive on-pad time. The CBCs are built in Boeing's factory in Decatur, Alabama. They are then loaded onto the M/V Delta Mariner, a roll-on/roll-off cargo vessel, and shipped to either launch pad. There, they are offloaded and rolled into a Horizontal Integration Facility (HIF), where they are mated with the second stages, which were shipped separately to the pad on the Delta Mariner. Also, in the HIF, the three CBCs of Heavy variant are mated to each other.

Various tests are performed, and then the vehicle is rolled horizontally to the pad, where the Fixed Pad Erector (FPE) is used to raise the vehicle to the vertical position, inside the MST. At this time, the GEM-60 solid motors, if any are required, are rolled to the pad and attached to the vehicle. After further testing, the payload (which has already been enclosed in its fairing) is transported to the pad, hoisted into the MST by a crane, and attached to the vehicle. Finally, on launch day, the MST is rolled away from the vehicle, and the vehicle is ready for launch.

A new launch pad would be needed to accomodate a Delta IV Super Heavy launch vehicle.

Delta Cryogenic Second Stage

The upper stage of the Delta IV, or DCSS, is nearly identical to that of the Delta III, however the tanks are friction stir welded and either stretched (in 4-meter variants), or have a larger diameter (5-meter variants). The second stage is powered by a Pratt & Whitney RL-10B2 engine, which features an extendable carbon-carbon nozzle to improve specific impulse. Depending on variant, two different interstages are used to mate the first and second stages. A tapering interstage which narrows down from 5-meters to 4-meters in diameter is used on 4-meter variants, where a cylindrical interstage is used on 5-meter variants. Both interstages are built from composites.

Payload encapsulation

To encapsulate the satellite payload, a variety of different payload fairings are available. A stretched Delta III 4-meter composite payload fairing is used on 4-meter variants, where an enlarged, 5-meter composite fairing is used on 5-meter variants. A longer version of the latter is standard on the Heavy variant, and a Boeing-built Titan-IV derived 5-meter, aluminum isogrid payload fairing is also available for the Heavy.

At over 63 meters in length, the Delta IV has been the tallest rocket in active use since its first launch in 2002; it is taller than the Ariane 4 Titan IV, Atlas V, Ariane 5, Long March 5, Proton rocket, Buran, and Space Shuttle.

First Stage

The first-stage CBC consists of the RS-68 engine, The hydrogen (LH2) tank, center-body, liquid oxygen (LO2) tank, and interstage.The first stage CBC is powered by the Rocketdyne RS-68 engine, a state-of-the-art engine burning LO2and LH2cryogens, that iscapable of delivering 2,891 kN (650,000 lb) of thrust and having a specific impluse of 410 sec.The RS-68 can throttle down to 60% of fullthrust level in a simple, single-step throttle profile designed to enhance reliability. It featuresproven technologies with the use of standard materials and minimum part count.

The coaxial injector is derived from the Space Shuttle mainengine (SSME) and uses low-cost materials and advanced fabrication techniques. The thrust chamber is an innovative hot isostatic press (HIP)-bonded evolution of the SSME design. The engine has a 21.5 to 1 expansion ratio and employs a gas generator, two turbopumps, and a re-generatively cooled thrust chamber. The thrust chamber and nozzle are hydraulically gimbaled to provide pitch and yaw control. Roll control for single-CBC vehicles is provided during main engine burn by vectoring the RS-68 turbine exhaust gases. Roll control for the Heavy vehicle isprovided by gimbaling the RS-68 engines of the two strap-on LRBs.

Delta Iv Engine

In 2002 the RS-68 became the first large, liquid-fueled rocket engine designed in the U.S. since the Space Shuttle Main Engine (SSME) in the 1970s. The primary goal for the RS-68 was to reduce cost versus the SSME. Some sacrifice in chamber pressure and specific impulse was made, hurting efficiency; however, development time, part count, total cost, and assembly labor were reduced to a fraction of the SSME, despite the RS-68's significantly larger size. Typically, the RS-68 runs at 102% rated thrust for the first few minutes of flight, and then throttles down to 58% rated thrust before main engine cutoff. On the Heavy variant, the core CBC's engine throttles down to 58% rated thrust around 50 seconds after liftoff, while the strap-on CBCs remain at 102%. This allows the core CBC to conserve propellant and burn longer. After the strap-on CBCs separate, the core CBC's engine throttles back up to 102% before throttling back down to 58% prior to main engine cutoff.

The RS-68 engine is mounted to the lower thrust structure of the vehicle by a four-legged (quadrapod) thrust frame, and enclosed in a protective composite conical thermal shield. Above the thrust structure is an aluminum isogrid (a grid pattern machined out of the inside of the tank to reduce weight) liquid hydrogen tank, followed by a composite cylinder called the centerbody, an aluminum isogrid liquid oxygen tank, and a forward skirt. Along the back of the CBC is a cable tunnel to hold electrical and signal lines, and a tube to carry the liquid oxygen to the RS-68 from the tank. The CBC is of a constant, 5-meter, diameter.

RS-68 was designed to meet cost criteria. It operates at comparatively moderate chamber pressures using a basic gas generator cycle. The gas generator drives a turbopump. Turbine exhaust gases are vectored to provide first stage roll control. Rocketdyne borrowed some technology from the Space Shuttle Main Engine and from the Saturn J-2 engine, but much is new. The engine's part count was reduced through use of an ablative exhaust nozzle, for example. RS-68 engine testing began at Edwards Air Force Base, California in August 1998.

An upgrade of the Delta IV Heavy, using the higher-performance RS-68A engine, was successfully flight tested in a launch on June 29, 2012. This upgrade provides a roughly 13% improvement in payload capability to GTO. The new RS-68A is also planned to be used throughout the entire Delta IV family, where at 106% thrust it will provide a roughly 7ˆ11% improvement in GTO payload (although this higher power level may require structural changes; running the engine at the current 102% produces a smaller improvement but requires less modification).

A program to upgrade the RS-68 engine to an "RS-68A" variant resulted in the first hot fire test of a prototype engine at Stennis Space Center in September 2008.  The first three production engines, Nos. 30003-300005, were delivered from Stennis to Decatur during March-April 2011 after completing their hot fire acceptance tests.  At the time, their first flight, on a Delta 4 Heavy, was expected to occur during 2012. RS-68A produces 319.79 tonnes of sea-level thrust with specific impulse improved by about 2 percent. The engine should substantially increase Delta IV Heavy performance, especially on LEO missions.

Delta IV Heavy

The Delta IV Heavy (Delta 9250H) is similar to the Medium+ (5,2), except that it uses two additional CBCs instead of using GEMs. These are strap-on boosters which are separated earlier in the flight than the center CBC. The Delta IV Heavy also features a stretched 5-meter composite payload fairing. An aluminum trisector (3 part) fairing derived from the Titan IV fairing is also available. This was first used on the DSP-23 flight.

On Delta IV Heavy flights, all three CBCs ignite on the pad. The core CBC engine throttles down to 57% about 50 seconds after liftoff. The twin strap-on booster CBC units burn at full thrust until shortly before they complete their burns.  The strap-on units are jettisonned about 242 seconds after liftoff. The core flies on for another 90-plus seconds, returning to full-throttle for more than 65 of those seconds.

Capacity (separated spacecraft mass) of the Delta IV Heavy:

geosynchronous transfer orbit (GTO) 13,130 kg (28,950 lb), more than any other currently available launch vehicle.

geosynchronous orbit (GEO) 6,275 kg
escape orbit 9,306 kg
C3 performance of 30 km”s-2: 5,228 kg
C3 performance of 60 km”s-2: 2,521 kg

The Heavy's total mass at launch is approximately 733,000 kg, much less than that of the
Space Shuttle (2,040,000 kg).

Future variants Delta IV evolution

Possible future upgrades for the Delta IV include adding extra strap-on solid motors to boost capacity, higher-thrust main engines, lighter materials, higher-thrust second stages, more (up to six) strap-on CBCs, and a cryogenic propellant cross feed from strap on boosters to the common core. These modifications could potentially increase the mass of the payload delivered to LEO to 100 tonns (100,000kg) with seven CBCs.

Another possible upgrade to the Delta IV family is the creation of new variants by the addition of extra solid motors. One such modification, the Medium+(4,4), would pair the four GEM-60s of the M+(5,4) with the upper stage and fairing of the (4,2). This would theoretically provide a GTO payload of 7,500 kg (16,600 lb) and an LEO payload of 14,800kg (32,700 lb). This is the simplest variant to implement and is available within 36 months of the first order. Two other possible versions, the Medium+(5,6) and (5,8), would add two or four extra GEM-60s to the (5,4) variant, respectively. These would provide significantly higher performance (up to 9,200 kg/20,200 lb to GTO for the M+(5,8)) but would require more extensive modifications to the vehicle, such as adding the extra attach points and changes to cope with the different flight loads. They would also require pad and infrastructure changes. The Medium+(5,6) and (5,8) can be available within 48 months of the first order.

Delta IV-H

LEO Payload   22.50 t (1)
(metric tons)  21.50 t (2)
500 km x  
(1) 51.6 deg  
(2) 90 deg    
 
GTO 10.75 t  
Payload  
1500 m/s  
to GEO*  
(metric tons)  
 
GTO Payload 1800 m/s to GEO (metric tons) 12.50 t

 

Configuration 3CBC + 5mS2(1) + 5mPF(2)
LIftoff Height (meters)   71.65 m
Liftoff Mass (metric tons) No Payload 732 t

* GEO: Geosynchronous Earth Orbit

** Dry mass for Delta IV Medium version believed to include 5-4 meter interstage. Dry mass for Delta IV Medium 5-5 meter version interstage and for Delta IV Heavy versions with nose cones or 5 meter adapter are believed to weigh about one metric ton more than Medium CBC

*** Propellant loadings for GTO missions shown. Propellant loadings would be less for LEO missions with heavy payloads.  Stage 2 masses do not include payload attachment fittings, which weigh 0.24 t to 0.4 t. 

Common Booster Core (CBC) First Stage   
Diameter (m)  5.1 m
Length (m)    36.6 m 
Usable Propellant Mass (tons)    ~204 t
Burnout Mass (tons)      ~27 t/28 t**
Total Mass (tons)  ~231/232 t**
Thrust(SL tons)   300.41 t
Burn Time (sec)    242-333 s
ISP (SL sec)      357 s

**Delta IV Heavy versions with nose cones or 5 meter adapter are believed to weigh about
one metric ton more than Medium CBC.

*** Propellant loadings for GTO missions shown. Propellant loadings would be less for LEO missions with heavy payloads.

Vehicle Delta IV Heavy  
LEO Payload   22.50 t (1)
Liftoff Mass (metric tons) No Payload    732 t
Mass Fraction  .3
Thrust      319.79+319.79+185.48=825.05
Thrust to Weight     1.13

Assumptions: Core CBC at 58% at liftoff and 100% at booster separation and 5 CBC Boosters at 106% thrust at liftoff.

Vehicle Delta IV Super Heavy   
LEO Payload    80 t    
Liftoff Mass (metric tons) No Payload  1464 t
Mass Fraction   .68
Thrust     1784.43 t
Thrust to Weight (T/W)       1.21

Assumptions: Core CBC at 58% and 5 CBC Boosters at 106% thrust at liftoff.

The vehicle would have a very good T/W allowing for quick accelleration. The vehicle would also have a very good payload mass fraction.

Three of the five strap-on units are jettisonned about 247.9 seconds after liftoff.  The core and two strap-on CBCs flies on for another 90-plus seconds before the two remaining boosters are shut down. The core continues to burn for another 124 seconds before main engine shutdown.

Launch

Core CBC Ignition 58% Thrust   T+0 sec
Strap-on CBC Igition (Five) 106% Thrust     T+1 sec
Engines throttle down on two CBCs to 58% Thrust T+55 sec
Maximum Dynamic Pressure (Max Q)   T+80 sec
Strap-on CBC Jettison (3)    T+242 sec
Engine shutdown 2 CBC   T+332.7 sec
Main engine cut-off (MECO) at         T+456 sec

Direct injection into a 100 by 185 nautical mile (nmi) parking orbit with an inclination of 28.8 deg.

Engine firing

First Stage    58% -  456 sec
Boosters (3)   106% -  242 sec
Boosters (2)  106% -  55 sec, 58% - 332.7 sec

Two attached boosters would remain with the core CBC stage as payload mass. This mass is estimated at 54 metric tons. Since the total payload mass is 80 metric tons the Delta Iv Super Heavy could lift two CBC boosters plus approximately 26 tons of additional payload.

Burnout Mass (tons)                                                27 t x 2 = 54 t

Orbit Circularization

Direct Injection

A direct Injection into LEO is possible using the RS-68 main engine on the CBC first stage. In this scenario the engine never shuts down until reaching the correct speed and altitude (the engine is not restartable).

OMS Injection

Assuming an upper stage with an OMS rocket system the engine would place the payload and CBCs into a circular orbit after first stage RS-68 shut down. This option would require the development of a special upper stage with two or more OMS (most likely four) engines placed at the top of the CBC and angled to fire without impacting the CBCs. Since the goal is to access the LOX tanks as habit the OMS should be placed on top of the Payload section.

The best option considering the proposed altitude in LEO would be direct injection with a small OMS/RCS used once on orbit. One low cost option for this might be the Russian Fraget stage.

Design Options

Shorter Boosters

A few more tonnes LEO payload could be squeezed out of Delta 4 by shrinking the CBCs, allowing the upper stage to grow. Shrinking the CBC tanks, and propellant load, by 13% or so allows the upper stage to carry nearly 130 tonnes of propellant while still meeting the minimum T/W values.  The upper stage would need six RL10s or perhaps a single J-2 engine.  Total vehicle height would increase by perhaps 5-10 meters. 

Longer Upper-stage

Delta IV Heavy could be modified to lift substantially heavier LEO payloads with a new upper stage powered by an RL10 cluster or J-2 engine.  An upper stage carrying nearly 48 tonnes of propellant fitted with 3 RL10s could orbit nearly 40 tonnes (88,000 lbs) while maintaining a liftoff T/W greater than 1.20 and an upper stage T/W greater than 0.35.  This assumes Centaur-type RL10 engines. 

Cross feed

Propellant cross feeding from the CBC Boosters could be benfitial in that it would allow droping the Boosters earlier while providing the Core stage with a full propellant load at Booster separation.

Residual Propellant

The CBC will have some residual Propellants in gasous form. These propellants could potentially be used in a regenerative LOX/hydrogen fuel cell.

Potential Problems

1. Using a total of 5 CBC Boosters and dropping three of them might put the vehicle off balance.

2. Approximately 54 metric tons of payload mass would be lost on each flight

3. No means to control mass on orbit thus requiring a new OMS/RCS section. A modified
Russian Fregat vehicle might serve this purpose.

4. Obtaining additional mass on orbit via future launches of Delta IV and Delta IV Heavy launch vehicles would be problematic as they reenter the first stages suborbital and
achieve orbit using an upper stage.

5. Assuming that the payload and CBC remain attached and that a hatch is constructed
into the CBC LOX tank the tank could potentially be used in space as a habitat. However,
the tank is constructed of thin aluminum and has no insulation. Therefore, the tank would
be hot or cold depending on the amount of sunlight the tank is subjected too. If shielded from the sun the tank would be very cold all the time.

6. Launching raw materials to construct solar panels into space may require more mass on orbit than launching completed solar panels.

7. Launch Vehicle development cost would be high and a new launch pad would be needed.
An alternative might be the government paid for Space Launch System (SLS) and use the
upper stage as the habitat.

8. Orbit is low and would require substantial amounts of reboot propellant.

Space Manufacturing

With a Burnout Mass (including resudial propellants) of approximately 27,000kg (mostly aluminum structures), the tanks could be recycled in space and provide a substantial amount of constuction materials. Of particular interest for SBSP would be the use of the aluminum to fabricate large reflectors. There are a large number of papers related to construction space structures from the space shuttle external tanks (ET) and much of the proposed technology would be the same using the CBCs.

Time to First Power

Since the purpose of the facility is to produce solar panels in space for SBSP this analysis will take a quick look at the feasibility of such a project as the ability to generate revenues quickly will be a driving factor in the success or failure of SBSP.

Space-based Solar Power (SBSP)

The orbital location of the SBSP Satellite(s) will determine the mass of the SBSP satellite transmitter. While most past concepts placed the SBSP satellite in GEO there are other perhaps better locations. One possible location would be a 6-hour orbit at 10,300km. This orbit lies between the inner and outter Van Allen radiation belts (the sweet spot) and is only 28.6% of the distance of GEO. This orbit would allow the satellite tranmitter to be only 28.6% the size of a GEO Power satellite (PowerSat) transmitter. This orbit would have approximately 12% shadow time per orbit. An even better alternative would be the Space Grid. The Space Grid uses a sun synchronous near polar orbit at 800km and therefore never enters the Earth's shadow. The energy produced by the PowerSat is beamed to microwave reflectors in equatorial orbit and reflected to the rectenna on the Earth's surface. An improved version of the Space Grid places the PowerSat in a 2,722km sun synchronous orbit at 110 degrees that is closer to the reflectors and therefore has a shorter beam distance. This allows for an even smaller transmitter.

Minium Power Levels

GEO PowerSat 5.0  gigawatts
Sweet Spot    1.43 gigawatts
Space Grid   1.0  gigawatts
Improved Space Grid 0.8  gigawatts

The minumim power level is the smallest satellite that can operate at that location. Three equally spaced PowerSats located in the 6-hour orbit would produce 4.29 gigawatts. These satellites could provide near constant power to three equally spaced ground rectennas. The Space Grid and Improved Space Grid can provide 24/7 energy while allowing the launch of much smaller satellites.

Beam Frequency and Efficiency

Assuming the use of a 38 Ghz microwave beam frequency the transmitter mass could be reduce by a factor of approximatily 15 compared to the orginal 2.4 Ghz frequency with a power loss of approximately 8% (Greater losses during heavy clouds and/or rain).

Transmitter Mass

Frequency 2.4Ghz  5.8Ghz   30Ghz
GEO Mass 13,000,000kg 6,500,000kg 866,666kg
Sweet Spot 3,718,000kg  1,859,000kg 247,866kg

The total transmitter mass of a PowerSat in the 6-hour orbit would be 247,866kg. Transmitter mass assumes the use of many small, low power masers. This is not mass efficient and the use of of powerful kelstrons combined with a low mass inflatable microwave reflector would be much more mass efficient.

Transmitter mass using kelstrons and inflatable reflectors (10x reduction in mass)

Transmitter Mass

Frequency 2.4Ghz 5.8Ghz 38Ghz
GEO Mass  1,300,000kg 650,000kg 86,666kg
Sweet Spot 371,800kg 185,900kg 24,786kg

Concentrated Solar Power (CSP)

Using Concentrated Solar Power (CSP) at 2,000 suns concentration (demonstrated by IBM in 2008) the production of 1.43 GW would require solar cells with a mass of only 17,875 kg.

Solar input 200 watts per square centimeter
Efficiency 40%
Electrical Output 80 Watts per square centimeter
Cell mass 1 mg per square centimeter
1,430,000,000 watts / 80 watts per cell = 17,875,000 cells
17,875,000 cells x 1 mg per cell = 17,875 kg

With a lift capabilty of approximately 80,000kg a Delta IV SH could place enough solar cells into orbit for 4.48 PowerSats of 1.43 GW power output each. This does not include structural mass, reflector/concentrator, or radiator mass, etc. With a transmiter mass of 24,786kg and solar cell mass of 17,875kg for a total mass of 42,661kg a single PowerSat could be launched into orbit using the same proposed (or smaller) launch vehicle with mass to spare for satellite structure, reflectors, radiators, etc. As shown below, increases in solar concentration levels will substantially reduce SBSP satellite sutrctural mass.

NASA 1980 Option 1: 1x Concentration, 16% efficient PV, 5GW, Mass 51,000,000kg,
Transmitter 13,000,000kg, Power 38,000,000kg

NASA 1980 Option 2: 2x Concentration, 20% efficient PV, 5GW, Mass 34,000,000kg,
Transmitter 13,000,000kg, Power 21,000,000kg

ISC 2010: 4x Concentration, 40% efficient PV, 5GW, Mass 18,250,000kg,
Transmitter 13,000,000kg, Power 5,250,000kg

Using concentrated solar power at 2,000 suns concentration would reduce solar cell mass by 90%. Additionally, it would reduce supporting structural mass by 90%. This large reduction is mass removes the need for in-space production of SBSP satellite structural components.

Conclusion

This is a rough order of magnitude (ROM) estimate. While the ideal of constructing a human habitated solar manfacturing facility out of Delta IV CBCs is very innovative the idea is expensive and not cost effective compared to other alternatives. It is technically feasible to use a Delta IV Super Heavy Launch Vehicle using a core CBC and five booster CBCs to place the core stage and two CBC Boosters into LEO. However, the substantial loss of payload would suggest that an inflatable habitat might be a better solution for the proposed habitat facility than lifting the empty CBC Boosters into orbit. Obtaining additional materials via future launches of Delta IVs and Delta IV Heavy vehicles is unlikely as they normally reenter suborbital. Additionally, the current state of space solar technology would suggest that the proposed solar manufacturing facility is already outdated as complete PowerSats could be placed into orbit without in-space assembly using the same Delta Iv Super Heavy launch vehicle being proposed (or SLS). This would remove the need for humans living in space at a manufacturing facility and the up mass needed to support human habition. Many past concepts have attempted to solve the SBSP satellite mass problem by very large launch vehicles concepts and massive space infrastructure rather than focusing on the real problem, which is satellite mass. The deployment of SBSP Satellites does not require a human habitat in space.

Recommmendations

It is not recommended that additional analysis be undertaken for this concept as the concept is technically outdated. Review the current and near term state of the art of space solar cell efficiency, microwave technology and orbital power beaming. Focus future efforts on concentrated solar power production in space.

If I can be of additional service please let me know.

Semper Fidelis
Royce Jones

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