Aerospace Gallery

Lunar cycler centrifuge

A living quarters module, secured to the end of a centrifuge boom, swings into the foreground while an unmanned cargo ship prepares to dock in the upper left. Both are falling toward the moon at a leisurely 1, 500 miles per hour. On the upper right abutting the orange propellant tanks, is the blue glow of one of the cycler's four ion engines. These engines may be all that's required to maintain the long-term integrity of the cycler's orbit.
Studies have shown that human health can suffer in the absence of gravity. Physiological hazards include loss of bone mass and diminished cardiovascular performance. While regular exercise can mitigate microgravity's deleterious effects, it may be determined that the best therapy would be a simulated gravity environment. Unfortunately nature appears to offer few options for simulating gravity, however a technologically feasible solution would be the employment of a centrifuge.
A centrifuge is a mechanical device that puts an object in rotation around a fixed axis, resulting in a gravity-simulating force perpendicular to the axis. Small scale centrifuges are used on Earth to quickly separate substances of varying density. In the microgravity of space, a large centrifuge could be constructed, not to separate substances, but to simulate gravity for human occupants. In the image above envisions a centrifuge with two booms, each with a radius of 100 feet, and each secured to a living quarters module with accommodations for six. A rotation rate of two revolutions per minute would generate a force equal to one-sixth the gravitational force at the Earth's surface, which happens to be that of the moon's.
Given the enormous engineering challenges, it would have to be demonstrated that even a force of one-sixth the Earth's gravity would go a long way toward ensuring human health. (Of course, larger centrifuges have been envisioned, from the massive two-wheeled space station in the movie 2001: A Space Odyssey, to a tethered version with a radius of a half-mile under consideration for Mars missions.)
While spinning a centrifuge at a faster rate would simulate a greater gravitational force, in this case the 100 foot radius would result in a force gradient that could cause its own physiological hazard, i.e. standing humans would experience a noticeably greater gravitational-like force at their feet than at their heads

© Walter Myers/Stocktrek Images

Illustration of a space shuttle re-entering the Earths atmosphere

Illustration of a space shuttle re-entering the Earth's atmosphere. In order for the Space Shuttle to return to Earth it must shed 18, 000 miles per hour of velocity and descend low enough to make an unpowered glide to a landing strip. With 115 tons of vehicle traveling fast enough to circle the globe once every 90 minutes, there is a tremendous amount of kinetic energy to dispose of. The Shuttle disposes this energy like every other manned space vehicle: it uses the Earth's atmosphere to convert its kinetic energy into heat. The Shuttle does this by slowly descending into the atmosphere bellyside-down at a 40 degree angle. This presents a large, blunt surface to the rushing air that continues to slow the orbiter for the next 16 minutes.
Through a combination of friction and compression, the temperature of the air around the Shuttle rises to 3, 000 A°F, hot enough to ionize the air into a glowing plasma trail that extends for miles behind the Shuttle. One effect of this plasma is to block all radio contact between the orbiter and ground control during the duration of reentry.
The Shuttle withstands the punishment of reentry via a thermal protection system that consists of thousands of individual silica tiles. The tiles, which are essentially bricks of very pure quartz sand, prevent heat transfer to the underlying orbiter aluminum skin and structure

© Walter Myers/Stocktrek Images

A reusable lunar shuttle prepares to dock with a lunar cycler

A reusable lunar shuttle, recently launched from the moon, prepares to dock with a lunar cycler. The lunar shuttle has a capacity for six crew and passengers and can deliver travelers to a lunar base without them ever having to venture outside.
The shuttle docks near the top of the lunar cycler stack where multiple docking ports can accommodate a variety of spacecraft. Just below the topmost antenna of the cycler is an observation module with an array of windows for viewing and managing docking operations from within the cycler. At the bottom of the scene, docked left and right to the cycler, is a pair of Orion class spacecraft that serve as life boats for the cycler's inhabitants. Should the need ever arise, each lifeboat can ferry six inhabitants safely to Earth.
The design of this lunar shuttle and cycler is purely fanciful, based upon what astronautical engineering might accomplish within the next 75 years

© Walter Myers/Stocktrek Images