Deviation Actions

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Mars Courier Mission, Earth-Escape Tank Jettison



Note: The full resolution full size artwork is currently available to my Beta Level and higher patrons. See details on my Patreon page.

The two outboard tanks contain Earth-escape/Mars trajectory insertion propellant. These are jettisoned immediately after the burn.

Jettison Procedure

The vehicle performs a 180 degree pitch maneuver, flipping end for end to face backward along its course, this minimizes the risk the jettisoned tanks will strike the vehicle. The ideal path is that both tanks move outward from the body of the CMOD/Habitat/Payload, Propellant-tank stack and propulsion bus, passing the CMOD/Hab and payload as they decelerate away from the spacecraft.

Prior to locking clamp release, LH2 transfer valves are closed and lines are decoupled, tension is slacked on tank stabilization straps (8 places at fore and aft ends of the tanks, dorsal and ventral sides) and the straps are cut at the point where they secure to the center-line-tank, the straps are reeled onto rollers on the soon to be jettisoned tanks, this secures the straps and prevents them from whipping about and possibly striking the center-line-tank when the locking clamp is released.

The locking clamp mechanism is a set of four clamps, two per tank, situated fore and aft center-line with matching positions on outboard tank and center-line tank on each facing side respectively.

The locking clamp consists of a clamp surrounding a spring-loaded pin mounted on the outboard tank side, and a receiver socket for the pin surrounded by an edged ring, which would be the grasp-point for the clamp mounted on the center-line tank. When the straps and clamp are released the spring loaded pin is free to push against its receiver on the center-line tank and this pushes the depleted tanks laterally away from the center-line tank and tank stack delivering initial outward momentum to the jettisoned tanks.

Once the tanks have moved to a safe distance the separation motors fire, these deliver thrust from three nozzles, (fore and aft positions on dorsal and ventral sides of the tank) first the inboard (relative to the tank stack) 40 degree downward angled thrusters fire, then the downward thruster fires in conjunction with the angled thrusters.

Since the orientation of the spacecraft has reversed 180 degrees relative to its direction of travel the jettisoned tanks will fall away, decelerating relative to the spacecraft, they will pass outward and beyond the CMOD/Habitat/Payload stack without danger of striking the radiator panels or tensioning cable system.

Spacecraft design is derived from the following NASA technical memorandum:

NASA TM X-2772 Link: Reactor Moderator, Pressure Vessel, And Heat Rejection System of An Open-Cycle Gas-Core Nuclear Rocket Concept

NASA TM X-67823 Link: Gas Core Rocket Reactors-A New Look

NASA TM X-67927 Link: Crew Radiation Dose From The Plume of A High Impulse Gas-Core Nuclear Rocket During A Mars Mission

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A number of talented individuals contributed to this project through participation in discussions on my G+, special thanks are due to Luke Campbell of PNNL, Winchell Chung of Atomic Rockets, Ron Fischer of Weta Digital, and Dogmatic Pyrrhonist talented designer of KSP mods, and John Reiher author of fine SF and founder of Real Spaceship Designs.
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© 2016 - 2023 William-Black
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DistinguishedPhysics's avatar
Fantastic! Incredible attention to detail, for sure. You've earned a watcher ^~^