This paper examines a concept that uses the Space Shuttle to place a fractional gravity laboratory in space, and recommends a feasibility study to determine the problems, hazards, risks, and costs involved to implement such an undertaking

Wilkins, Richard C.

English

Embry-Riddle Aeronautical University

The Space Congress® Proceedings 1994 (31st) Space Exploration and Utilization for the Good of the World Apr 26th, 2:00 PM - 5:00 PM Paper Session I-C - A Proposed Experiment for Generating Fractional Gravity in Space Utilizing the Space Shuttle as a Laboratory Richard C. Wilkins Engineering Specialist, Lockheed Space Operations Company Follow this and additional works at: https://commons.erau.edu/space-congress-proceedings Scholarly Commons Citation Wilkins, Richard C., "Paper Session I-C - A Proposed Experiment for Generating Fractional Gravity in Space Utilizing the Space Shuttle as a Laboratory" (1994). The Space Congress® Proceedings. 3. https://commons.erau.edu/space-congress-proceedings/proceedings-1994-31st/april-26-1994/3 This Event is brought to you for free and open access by the Conferences at Scholarly Commons. It has been accepted for inclusion in The Space Congress® Proceedings by an authorized administrator of Scholarly Commons. For more information, please contact commons@erau.edu. A PROPOSED EXPERIMENT FOR GENERATING FRACTIONAL GRAVITY IN SPACE UTILIZING THE SPACE SHUTTLE AS A IABORATORY by Richard C. (Dick) Wilkins Engineering Specialist Lockheed Space Operations Company MS' LS0-125 1100 Lockheed Way Titusville, Florida 32780 (4-07) 383-2200, Ext. 2960 ABSTRACT The progressive deterioration of the human body while being exposed to zero gravity is a prob-lem that must be dealt with before humans can ever expect to live and work in space for ex* tended periods of time. The cost of frequent short term missions can be a significant motivator for considering the possibility of longer missions and extended stays in space. It appears that the problems associated with long terms of weightlessness cannot be resolved within a zero gravity atmosphere, and that the presence of some fractional amount of gravity is necessary. If this is so, then how do we go about determining what this optimum "G" is? Presently, the only two data points that we have are the full gravity of earth and the zero gravity of space. Is there a fractional gravity, somewhere between these two data points, where these prob-lems do not occur? Do they all occur at the same or at various levels?These and many other ques-tions can only be answered by experiment in a fiactional gravity laboratory, which can only ex-isl in a zero gravity environment. This paper examines a concept that uses the Space Shuttle to plac.e a fractional gravity labo-ratory in space, and recommends a feasibility study to determine the problems, hazards, risks, and costs involved to implement such an under-taking. INTRQDUCTION Some of the basic requirements for a fractional gravity laboratory in space are: • An environmental control and life support system for at least three people. • Enough room for moving around freely and exercising. • A communication and data acquisition sys-tem. • The capability to support work excursions outside the laboratory. • A system of various size thrusters for ma-neuvering in and out of a gravity configura-tion. To build and launch a laboratory such as this, from scratch, would indeed be a very complex and expensive undertaking. However, if a labo-ratory that meets these requirements already ex-ists (The Orbiter) and a system capable of launching this laboratory is in place and opera-tional (The Shuttle) then the fractional gravity laboratory now becomes more attainable. TIIE CONCEPT This experiment consists of placing two Shuttle Orbiters in the same orbit in close proximity to each other so they can work together. They should be positioned so that the open payload bays are facing each other. From this position, a rigid span of a predetermined length is erected from a strongback assembly in the payload bays of each Orbiter. (See figure 1.) The ends of the rigid spans from each Orbiter are then mated to each other. This connection should have a marker/beacon to identify the exact center be-tween Orbiters. Figure 1. The Orbiters can now begin to rotate about this marked center of the total span so that the plane of rotation is perpendicular to the path of the orbit. The angular velocity can now be equally and incrementally increased to produce the frac-tional gravity selec1ed for the mission. (See fig-ure 2.) The fractional gravity selected for a mission will restore that same fractional weight to each Or-biter. Consequently, the strongback assembly, rigid span, and attach points will have to be de-signed to withstand 1.5 to 2.0 times these loads. The payload bay doors will also require special bracing for this type of mission. THE THEORY What is involved here is simply an application of the basic principle of centrifugal force. Since the radial acceleration is the product of the an-gular velocity and the length of the radius of rotation, then different combinations of angular velocities and radial lengths can produce the same acceleration. For example; 1/4 gravity (an acceleration of 8.05 ft/sec2) can be generated with a 50 ft radius by making a complete revo-lution every 15.659 seconds, or with a 90 ft ra-dius and a full revolution every 21 seconds. EVALUATION An evaluation of this proposed experiment should be a feasibility study that includes the following: 1. Perform a stability and controls analysis for all the maneuvers in orbit from deploy-ment through recovery. 2. Prepare a mission requirements document that includes all the requirements that are unique to this type of mission. 3. Prepare a Preliminary Engineering Report (PER) that describes the design require-3-41 Figure2. ments for the rigid span, strongback, at-tach points, payload bay door supports, and any other support equipment or modi-fications that may be required. 4. Perform a quantitative risk assessment, mission hazard analysis, and failure modes and effects analysis. 5. Identify problems and hazards for process-ing and launching two Shuttles within 24 hours of each other, with recommended waivers and acceptance rationale. 6. Identify problems and hazards for two Or-biters working in close proximity to each 3-42 other, while on-orbit, with recommended waivers and acceptance rationale. 7. Prepare a Cost Benefit Analysis to deter-mine the relative worth of this experiment as opposed to a competing alternative. CONCIJJS!ON This fractional gravity experiment could cer-tainly reveal the type of information and data that can provide answers to many of the long standing questions about weightlessness. It may even provide the direction and criteria needed to design long duration missions in space. In addition to advancing our technology in this area, fractional gravity could be adapted to Space Station through a simple reconfiguration of the habitat modules, and the addition of rigid spans and thrusters. (See figure 3.) This recon-figuration could have a significant impact on the operation of Space Station by reducing the launch rate required to keep the station manned. Figure3. 3-43 

Paper Session I-C - A Proposed Experiment for Generating Fractional Gravity in Space Utilizing the Space Shuttle as a Laboratory

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Paper Session I-C - A Proposed Experiment for Generating Fractional Gravity in Space Utilizing the Space Shuttle as a Laboratory

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