Robots in Space Suits

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  • The lack of long endurance lubricants in vacuum could be worked around by robots wearing space suits. While usually the spacesuit is made to fit the person, with robots the possibility arises that robots could be made to fit spacesuits. So let it be plain, what is meant is not a man shaped robot wearing a man's suit, but robots in spacesuits with six or more legs each and as many arms as required for the task. The pressure maintained by a robot's Spacesuit might be just the sum of the vapor pressure of a low-vapor-pressure lubricant and an inert gas to a pressure a couple times more than the vapor pressure. Gas pressure is needed to keep bearing lubricants from evaporating. At least a gas tight covering of knee or elbow joints could be done with a bellows that has flanges pressed to points above and below the joint by threaded rings. Electrical power wire, control wire, and thermal management fluid hoses could run in a bundle outside of the bellows and have connectors for wires and hoses that would run around the bellows to the pressurized space around the joint . That way the wires and hoses could be disconnected, the bellows unfastened, and the joint unpinned for maintenance, including bellows replacement.
  • The astute reader will realize that this sort of joint covering will not work with rotary bearings of wheels rolling over the ground. So robots could walk and wheeled vehicles could have magnetic bearings (which do not require lubricants and thus would not need the protection of space suits). Vehicles with magnetic bearings would not be suitable for bouncing over rough terrain, but might give high speed performance over smooth Roads. Wheeled vehicles might work with ordinary greased bearings and frequent lube jobs, or the lubricant requirement might be solved by special grease and thermal management. The rotary bearing would be within the body of the robot ( as described in the Dust section of Long Endurance Rovers ) where thermal management could be effective. A wheeled robot could have gas tight sleeves covering some joints and not covering the wheels.
  • A multijointed arm covered with a gas tight envelope could hold a directional antenna constantly pointed at a ground station while connected to a rotating satellite in orbit. This would obviate the need for any slip rings for electrical connection between the antenna and satellite. For long life such a gas tight envelope should be covered by layers of foil or sheet sandwiched with three inch layers of vacuum as micrometeoroid protection. Such an arbitrarily pointable antenna and radome might be large enough to require that it be assembled in orbit rather than put into the payload of a rocket.
  • A telescope included within a gas tight covered arm would require optical quality glass for the portion of the envelope that it looks through, and for the portion of the micrometeoroid shield that it looks through. The glass portion of the micrometeoroid shield should be only one layer to minimize reflections. It should be made to be changed as needed to eliminate pitting. A roll control motor would keep the image from rolling as the telescope points one direction as the satellite rotates.
  • A bellows can hold a gas envelope around a hydraulic piston too, with some limitations in the structural shape and range of rotation of the bearings at each end of the piston. Sliders attached to the inside corners of the bellows folds could move along the cylinder maintaining the proper spacing. These slides would be nestable to not take up too much space along the cylinder when the piston is contracted, and yet not be flat like a washer to avoid binding. An example shape for such a slider can be described as a portion of a cylinder. For a slider on a 4 cm diameter hydraulic piston, the slider can be a portion of a 6 cm diameter cylinder. Bore a hole down the center of the cylinder 4.02 cm in diameter. Trace sine waves on the outside of the cylinder and on the wall of the bore hole, h' = 1 cm * sine (2 theta) and h'' 0.16 cm + h'. Connecting the sine waves by the set of radial line segments that terminate at each sine wave produces the upper and lower surfaces of the slider. Such sliders would nest in a stack 0.16 cm * the number of sliders plus one cm, yet the wavy shape would give the slider a thickness that makes binding less likely.
  • Besides instituting a program of putting robots in space suits, space suits for humans should be discontinued.