20,000 Leagues Above: subs in space? (science video)

Imagine the scene: a robust, steel-clad submarine, a titan of the deep, suddenly whisked away from the crushing embrace of Earth’s oceans and cast adrift in the vast, star-studded expanse of deep space. It’s a scenario that tickles the fancy, blending the realms of undersea exploration with cosmic voyaging—akin to the transformation seen in the legendary Space Battleship Yamato. But beyond the realms of science fiction, would a submarine actually make a decent spaceship?

At first glance, submarines and spaceships share some appealing similarities. Both are designed to operate in environments where humans cannot survive unaided, they’re sealed off from their hostile surroundings, and they recycle air and water to sustain their crews for extended periods. But when we dive deeper into the physics of undersea and outer space environments, the differences become starkly apparent.

Pressure Plays a Pivotal Role

Submarines are engineered to withstand immense pressure from the outside. They’re built to operate under the weight of countless tons of seawater bearing down on them. In contrast, a spaceship must maintain internal pressure to keep those inside alive in the vacuum of space, where there is no external pressure. If a submarine were suddenly exposed to the vacuum of space, its hull designed to resist compression might not fare well against expansion forces.

Temperature and Thermal Regulation

The cold, dark depths of the ocean have more in common with space than one might think, yet the thermal environment is markedly different. Submarines are insulated against the cold water around them but aren’t equipped to handle the extreme temperature variations in space, where sunlight and shadow can cause rapid shifts from scorching to freezing. Without the ocean’s water to regulate temperature, a submarine’s hull could undergo extreme stress and deformation.

Maneuvering and Propulsion

Underwater propulsion systems are designed to move through a dense medium, relying on propellers or jet propulsion. In the frictionless void of space, these systems would be utterly useless. Spacecraft maneuvering relies on thrusters and reaction wheels to orient and propel, a far cry from the principles that guide a submarine’s movement through water.

Life Support and Sustainability

While both submarines and spacecraft must recycle air and water, a spaceship must also manage the removal of CO₂ and other waste products over potentially longer durations without resupply. The closed-loop systems of a spacecraft are far more advanced, given the impossibility of opening a hatch for fresh air or taking on new supplies in the vacuum of space.

The Verdict on subs as spaceships…

Now, would a submarine also work as a spaceship? The straightforward answer is no—not without significant modifications that essentially change it from a submarine into a spacecraft. However, the thought experiment itself isn’t without value. It challenges engineers and dreamers alike to think outside the box, or in this case, outside their vessel. In the grand tradition of Space Battleship Yamato, transforming a submarine into a spacefaring vessel is a task for fiction, a delightful flight of fancy that sparks the imagination and fuels the fires of creativity. For the scientists, engineers, and storytellers among us, it’s a reminder that innovation often starts with the wildest questions.

But what the heck about spaceships as subs?

And, thanks to Twitter user olybuzz for this idea, what about the converse: when faced with the idea of a spaceship that can explore the dark depths of our oceans just as it navigates the vast expanses of space, we’re compelled to ponder: could a spaceship truly function as a submarine?

This concept isn’t new to fans of science fiction. The Flying Sub from the vintage TV series Voyage to the Bottom of the Sea offered a glimpse of such a dual-purpose vessel, capable of deep-sea diving and interstellar travel. Similarly, The Abyss teased our imaginations with underwater UFOs, or USOs (Unidentified Submerged Objects), hinting at technology beyond our understanding. But stepping away from the screen and into reality, could this concept hold water, or is it destined to sink?

The Challenges of Dual Environments

Space and the sea, two frontiers that challenge human exploration, each present unique obstacles. A spacecraft, designed to withstand the vacuum of space and the pressure of acceleration, faces a radically different set of stresses compared to those encountered underwater. While a spaceship is built to keep high internal pressure in, a submarine must resist high external pressure pressing in.

Material Matters

The materials and structure of a spacecraft, optimized for weight savings and protection against micrometeorites and radiation, might not endure the relentless squeeze of the ocean’s depths. Conversely, a submarine’s heavy, robust hull could be impractical for space travel, where every extra kilogram requires additional rocket fuel.

Thermal Dynamics

The abyssal cold of deep space is akin to the chill of the deep sea, yet the thermal management systems are worlds apart. A spaceship’s system must radiate heat away without the benefit of an atmosphere, whereas a submarine relies on surrounding water to moderate its temperature. Transitioning these systems to operate in both environments would be a formidable engineering challenge.

Navigating and Propulsion

In the void, spacecraft employ thrusters and gyroscopes for orientation and propulsion, a stark contrast to the propellers or jets of a submarine. Adapting a vehicle to traverse both space and sea would demand a hybrid propulsion system, capable of efficient movement in the frictionless vacuum and the resistant aquatic medium.

Life Support Synergy

Interestingly, the life support systems of spaceships and submarines share common ground, both recycling air and water to sustain their crews in isolated conditions. This synergy offers a glimmer of feasibility, suggesting that, with some adjustments, these systems might serve dual purposes.

The Verdict on spaceships as subs…

While engineering a spaceship-submarine hybrid presents a titanic array of technical hurdles, the spirit of human ingenuity thrives on such challenges. Current technology might not be up to the task, but the future is an ocean of possibilities, awaiting our exploration. Whether borne of necessity or curiosity, the quest to combine these two realms of exploration embodies our unyielding desire to push beyond the limits, to explore all that lies above and below. So, while a real-world Flying Sub might be on the distant horizon, the journey toward it continues to inspire, urging us onward in our quest to conquer the final frontiers.