In Memoriam T. Brian Gray
(1945-1996)


T. Brian Gray's Space Work Station


Brian Gray's Space Work Station

SPACE WORK STATION
Combining Capacity and Capability at Low Cost
(Extracts from a transcription of a 2-hour video presentation produced in 1991*)


T. Brian Gray
Electrical and Systems Engineer
Tucson, Arizona

Abstract
This presentation considers the integration of the space station program with a Shuttle Derived Cargo Vehicle (SDCV) program, and attempts to show that this integration would produce a more capable station at much lower cost, than previously considered space station designs.

Problem
Although the space station has repeatedly undergone redesigns and downsizing since its proposal in 1984, its cost keeps growing unacceptably. It is important that the space station be as affordable as possible. Low Earth Orbit or LEO as it is called, is the Earth's front porch. The Van Allen radiation belts protect LEO from most of the harmful radiation just as the front porch roof protects the porch from most of the unpleasant weather. If we cannot affordably stay on the front porch, we certainly can't afford to stroll through the neighborhood. If we cannot build a cost-effective space station, how can we expect the American taxpayers to pay for trips to the Moon and Mars?

In February of 1969 it was Nationally reported that NASA was planning for a "100-Man Station" and that the "Cost of such a station over a period of years has been estimated at in excess of $10 billion."(1) I assumed a cost of $30 billion for the 1969 100-man station and plotted the cost per astronaut for '69, '84 (8-man station for $8 billion), and 1992 (4-man station for $32 billion). The results are shown by the solid line in Figure 1. [Figure currently unavailable]

Why has the cost grown so great for this much smaller station? Has our space technological capability decreased in the last 22 years? No, its a result of less launch capability and more politics.

In 1969 we had the Saturn V booster, which could launch massive, completely furnished space station modules into orbit. Because we now have much less launch capability, the space station' modules, and every component within them, must be made as compact and as lightweight as is technically possible, and that is expensive.

Because there is not enough room within the modules for some of the equipment and experiments, they must be mounted externally, and therefore be designed to withstand the hostile elements of the space environment, and that is expensive.

Because there is no cost effective way of repairing or adjusting the external elements, and very little room to repair the internal elements, they must be made to be failure free. To make the elements that perfect, each of their components must be ultra-reliable or the complete systems must have extensive redundancy, and both of these options are very expensive.

SPACE STATION COST DRIVERS
POLITICAL

- Do Everything for Everyone

- Contracts by Congressional Districts vs. Ability and Technical Reputation

- Funding Instability

- Extensive, Redundant Design Studies
TECHNICAL

- Transportation: transportation to Low Earth Orbit has always been expensive, and unfortunately that is especially true of the Shuttle system. We need a different vehicle to launch our space station!

- Development of New Technology vs. Off-the-Shelf

- Ultra-Reliability: it is said that 90% of the cost of a space system is spent on achieving the last few percentage points of reliability. This is due to the inability to repair systems once they are launched. Thus extremely reliable elements and extensive redundancy are required to insure that orbiting systems will not fail; and both measures are extremely expensive. We need a cost-effective way of repairing space hardware in orbit!

- Single Unit vs. Mass Production: to be affordable, space station elements should be produced on an assembly line when ever possible; and should use existing assembly line produced elements where ever conceivable.

Solution
NASA's space station design has been crippled from the beginning by the 1984 political push to launch all payloads on the Shuttle, which eliminated the possibility of large or heavy space station modules. The expensive Shuttle safety precautions due to manned operation, eliminated the possibility of low cost launch of the space station elements.

I have found a way to design a Shuttle derived cargo vehicle that is affordable, because it is (more correctly - its components are) reusable. Thus large, completely furnished space station modules can be launched, which saves launch and assembly costs and reduces the expensive size and mass minimization requirements now imposed on each and every component of the current design.

The Space Work Station's Design Rules are as follow:
1. Avoid Design Complexity & Interdependency -- KISS
2. Use Existing Technology, Hardware & Systems
3. Avoid Engineering Problems vs. Solving Them
4. Maximize Automation: On the ground and in orbit
5. Avoid EVA by use of a Repair Facility
6. Maximize Flexibility and Boot-Strapping.

We should use existing Space Shuttle hardware for the critical launch phase:

- the nose and avionics module: this section contains avionics bays 1 and 2, the inertial measurement units, the accelerometers, the star tracker units, and the avionics cooling and fire safety systems;

- the forward reaction control system (or RCS) module: the RCS controls the attitude or orientation of the Orbiter; which way it is pointed. It has been designed to be an independent replaceable unit;

- the main engine module: the aft fuselage contains the three space shuttle main engines and all of the elements associated with the main propulsion system (propellant lines, thrust support structure, auxiliary propulsion units (APUs), hydraulic system and actuators to vector the main engines, flash evaporator and ammonia boiler cooling units, and avionics bays).

The Space Work Station has over ten times the internal volume of the US portion of the old (read: original Freedom Space Station) design, which was larger than the new (read: current International Space Station) design. Each of these large modules, essentially identical to the hydrogen tank portion of the current Shuttle system external tank, has over 53,000 cubic feet of internal volume. Each spoke of the rotating section includes two of the shuttle external tanks. Shuttle external tanks are extremely strong and lightweight and are produced on an assembly line as affordably as possible, since one is discarded each time the shuttle flies. The external tanks provide still more pressurized volume for storage in orbit. Each external tank adds over 73,000 cubic feet of storage space.

It can be assembled in phases. Phase I consists of one man-tended module and the truss. Artificial gravity is utilized in Phase II to simplify and lower the cost of fluid management within the rotating section. Phase II illustrates only one of many possible configurations made possible by utilizing these massive pressurized modules. There is no required EVA, and Phase II is completed after only four launches of the low cost shuttle derived Modular Cargo Vehicle (MCV).

Phase III would allow for additional growth: the length of the spokes can be increased easily since the cargo modules can be linearly bolted to each other in series until the desired length is reached. If no further spoke length is required, a phase IV expansion could build the rim of the wheel to become the familiar wheel space station like that proposed by Wehrner von Braun in the 50's, and that shown in the movie: "2001, Space Odyssey."

Modular Cargo Vehicle (MCV)
To lift heavy payloads, NASA considered shuttle derived cargo vehicles from 1978 to 1980, and again recently as the Shuttle C program, but these proposed vehicles would not be economically practical since they would be expendable. Unfortunately the Shuttle components are far too expensive to throw away on an expendable vehicle.

Consider instead a similar vehicle designed to be launched only to transportation nodes in space, the first node being the space station of course. There the expensive Shuttle propulsion and avionics components can be removed, and brought back to Earth in returning Shuttle Orbiters. Figure 2 shows a possible configuration for that low cost heavy lift vehicle built from already tested and proven shuttle components. I call it a Modular Cargo Vehicle. [Figure currently unavailable]

The propulsion system is identical to the Shuttle Orbiter, although those components dealing only with reentry and landing have been deleted. The nose module consists of the Shuttle forward reaction control system and the forward section of the cabin, which contains avionics bays one and two. As you can see a large fuel tank and one orbital maneuvering system (OMS) engine have been added to the basic structure and a panel has been added to close out and seal the avionics bay section. The complete nose module is released from the cargo vehicle at the space station and fits directly into the cargo bay of a shuttle orbiter which is ready to return to Earth.

The cargo module is derived from Shuttle external tank components and can be put to use as a large pressurized space station module in orbit. Each of these space station modules provides 53,470 cubic feet of pressurized volume. This is approximately 12 times the maximum internal volume of NASA's new downsized 27 foot long space station modules. The expensive weight and size reduction process required for the smaller modules can thus be avoided.

The MCV has extremely low development costs since over 98% of its components have been repeatedly space qualified with each Shuttle launch. Operational costs are 1/3 ($/lb.) those of the Shuttle

Orbital Pressurizable Hangar (OPH)
The first function of the hangar after the cargo has been removed is to make the return of the expensive elements of the engine module possible. The hangar's interior will be equipped with lighting and manipulating fixtures to aid in this process.

The engine module is obviously too large to fit into the Orbiter cargo bay, but contains components which are too expensive to discard. They are recovered utilizing a large pressurizable hangar, which is part of the first cargo module launched to the space station. The hangar is over 40 feet deep, and over 25 feet in diameter, the rest of the module is pressurized for habitation. As you can see the entire engine module fits within the hangar and the components can be removed by remotely controlled manipulators or by astronauts working within the pressurized shirt-sleeve environment of the hangar.

There are two hangars in the work station. One is here in the non-rotating module. . . The other is up here in the hub module. These hangars provide a cost-effective method of adjusting, repairing, and maintaining any orbiting element which can fit within its 25 foot inner diameter hatch. Thus external space station elements no longer have to be ultra reliable -- they can be cost effectively repaired without risky EVA (Extra Vehicular Activity -- that is an astronaut space walk). This greatly lowers the cost of the external space station components.

Beam Assembler
The hangars can contain large diameter payloads during launch, and the first large payload carried to the space station will be a Beam Assembler. The Beam Assembler I propose is a simplified, lighter, energy efficient version of this Grumman Beam Builder developed under a NASA contract over decade ago. The Grumman Beam Builder took construction grade aluminum rolls and strips and automatically formed and welded together lightweight beams suitable for construction in space. This concept is a step in the right direction since we will need beams for construction in space, but had some problems. The power required to weld the beams made it require too much power and the heavy equipment required to bend and weld the beams made it too heavy. Another problem was the complexity which made breakdowns too likely.

The Space Work Station's Beam Assembler produces beans that are composed of rigid preformed triangles joined by semirigid rails and flexible tension crosswires. Even though the side rails are not completely rigid, and can be rolled onto reels when separate from the triangles, the resulting completed beam is quite rigid, prevented from deforming by the crosswires. The pins that hold the rails to the triangle apexes are removable to allow the beam to be disassembled. Freed from the side rails, the triangles stack compactly against each other in a small fraction of the space occupied by the completed beam.

One advantage of the semi-rigid rails is that the beam can be curved by modifying the lengths of the cross wires as shown in figure 3 [Figure currently unavailable]. No modification of the beam assembler is required. Additional structure must be added next to the curved sections to compensate for this localized flexibility.

Unlike NASA's Beam Builder, the Beam Assembler automatically forms beams of unlimited length and shape which are used to form the Space Work Station truss. The final configuration formed by the Beam Assembler is a continuous loop around the Space Work Station, that forms a continuous railroad along which the mobile manipulators could travel.

Artificial Gravity
One of the major features of this space station design is artificial gravity. Before it was found that astronauts could tolerate micro-gravity for months at a time, it was assumed that artificial gravity would be required in any permanent space station. Because high rotations produce corriolis forces which would very likely produce very sick astronauts, the early designs had diameters on the order of 1,000 feet or more to produce Earth normal gravity at low rpms, revolutions per minute. Structures that large in space would be excessively expensive, and were dropped from consideration once it was determined that micro-gravity could be tolerated for three to six months with few serious side effects. The Soviet experience has shown that as flights increase beyond six months in length, that the side effects become less tolerable.

Almost all of the authorities assume that slow rotation artificial gravity would eliminate most if not all of the detrimental effects of micro-gravity and would be more desirable than mandatory heavy exercise for several hours a day or than experimenting with drugs, but it is assumed that such a system cannot be affordable at this time. Also, since it has never been demonstrated, it is doubtful that Congress would back such a very expensive unproven cure. Yet demonstrating artificial gravity to the public and Congress would settle what I consider the biggest question regarding the future of our space program.

Most of the experts agree that less than two rpm will probably be tolerable to all the astronauts. The assumption that has stopped a practical solution to the long term effects of space travel and habitation is that we need artificial gravity at an equivalent level to Earth's as a starting point. We should direct our efforts at first developing artificial gravity at the lunar level.

It turns out that, with the large cargo modules used as space station modules, simulated lunar gravity at only 1.6 rpm is technically easy to achieve. Cargo modules can be modified to include an extension cylinder which, when extended, increases the distance of the cargo module from the rotating hub (195 feet) to create lunar level artificial gravity with a rotation speed of only 1.6 rpm. This produces the complete range of artificial gravity from zero along the rotation axis to simulated lunar gravity at the far end. Under these conditions we will learn of the long term effects of lunar gravity, necessary to intelligently design a lunar base.

Rotating Assembly of Space Work Station

Under artificial gravity fluids behave similarly to the way they do on Earth, greatly simplifying such normal habitation needs as sinks, toilets, showers and kitchen facilities, and avoiding the high costs of unique zero-g systems.

Plants can be grown in artificial gravity for air and water purification, and to provide fresh vegetables. Artificial gravity at the lunar level will decrease if not eliminate the negative physiological effects of micro-gravity on astronauts.

The attitude stabilization produced by the gyroscopic effect of the rotation greatly reduces the requirement for attitude control propellants.

Major Advantages of the Space Work Station
1- Large size:
As previously mentioned, the Space Work Station has over thirty times the internal volume of the US portion of NASA's currently proposed Space Station with each cargo module providing over 53,000 cubic feet and each of the 4 external tanks adding another 73,050 cubic feet of storage space.

2- Capability:
The Space Work Station contains your choice of zero gravity, micro-gravity or lunar level gravity within large pressurizable hangars. Therefore, instead of being discarded or expensively built to be super-reliable, equipment can be dismantled or repaired in a shirt-sleeve environment, rather than in open space.

3- Heavy-Lift Vehicle and means for future space construction:
The Space Work Station makes a rapidly developed Heavy Lift Vehicle affordable and provides the Beam Assembler for future construction. A Heavy-Lift Vehicle allows for fewer, larger resupply missions, and the resupply module can become a permanent part of the station, or used to build future stations.

4- Artificial gravity:
Artificial gravity will probably allow longer orbital habitation by each astronaut. In addition, it will allow for better study of the effects of long-duration spaceflights or of long-term lunar stays on human beings.

If our advance into space depended only on technology, we would be much farther along by now. Unfortunately politics is involved, and nothing happens in politics without a strong pushing force. The impressive size and capabilities of the Space Work Station should favorably impress the public and Congress, providing more support for future projects, and will return the undisputed leadership in space and technology to the United States, and it is about time we did that.

Note:
(1) Aviation Week & Space Technology, February 24, 1969, p. 16

* Video presentation produced by Jeannette Jaquish. Screenshot used by permission.



A Proposal to Memorialize T. Brian Gray
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The Tucson L5 Space Society wishes to honor the memory of one of its most active and inventive members.

With his innovative and practical design for a cheaper, more functional and more practical space station, T. Brian Gray has made a significant contribution to the development of space exploration. We also believe T. Brian Gray was one of the first to suggest using shuttle components to build a largely re-usable cargo vehicle to effectively accelerate our establishment into space.

These contributions alone mark him as a truly original thinker and a true pioneer of space development. His ideas will surely inspire others to strive further to make us into a space-faring civilization.

In recognition for his contributions, it is hereby proposed that the Tucson L5 Space Society officially rename Mr. Gray's space station design the "T. Brian Gray Space Station."

His pioneering spirit will accompany us as we move into space.

Passed unanimously on November 9, 1996.



2003 The Tucson L5 Space Society.
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