“Warships of Sea and Space”
Form Follows Function Follows Technology — Part II by Jim Beall
NOTE: This is part two of a series by Jim Beall on warships past, present, and future. Part one can be found here.
A previous article (Note 1) traced how the form of ship designs depended not just on the function of the craft, but also on the technology available to the designers. How might a crewed space warship look using only current (or near-term) technology? Perhaps more important, how do we get from the first image below to the second?
|Apollo—Artist Drawing||Cobra Trilogy by Timothy Zahn|
|Source—NASA—Public Domain||Image Courtesy of Baen Books|
Any answer to those question has to address how the design deals with three of the main challenges of space:
2) Radiation, and
3) Freefall (zero-g).
Certain aspects of these challenges remain unsolved. That is why Science Fiction (SF) authors wanting large ships or great capabilities in their stories routinely postulate new inventions and even completely fictional technologies.
It may appear counterintuitive, but interplanetary travel might not be possible if space were not a vacuum. Otherwise, frictional resistance and consequent hull heating would prevent the great velocities needed to reach distant destinations in any practical amount of time. (Note 3) The presence of vacuum, however, poses different and even more formidable problems. The most obvious one is that crewed ships must have constant atmospheric life support which, in turn, requires onboard systems of substantial cost and complexity.
The absence of gas pressure can also adversely affect materials. (Note 4) One important mechanism, called "outgassing," is the release of volatiles by evaporation, sublimation, chemical reactions, and desorption (the reverse of absorption). It occurs most frequently when materials are exposed to reduced pressures or higher temperatures. Two familiar cases are the visible tails of comets as they warm up during their passage through the inner Solar System and, more prosaically, that "new car smell."
Outgassing changes the properties of materials. Once surface layers of oxidation or volatiles have been removed, bare surfaces can "cold weld" together (Note 5), including (formerly) moving parts. The emitted volatiles can redeposit on surfaces causing things like lens blurring, short circuits, human health effects, and even arc flash.
Arc Flash—You Do Not Want This on Your Ship!
Image Courtesy of PCX Holding LLC https://pcxcorp.com/
Plastics and lubricants are prime candidates for use in spacecraft but, unfortunately, both are particularly susceptible to outgassing. Large scale testing programs aimed at reducing the problem have identified some materials less vulnerable to outgassing (such as dry lubricants including graphite), treatments (e.g., coatings) and methods to pre-condition others (like baking components). Various products of those scientific and engineering efforts to address outgassing include enhanced testing techniques, such as Standard ASTM E1559 (Note 6). Successful space programs only become possible after a great many systematic programs that produce such standards. Developing those standards requires major investments in skilled personnel, hardware and facilities (Note 7). As has been said by many over the years, "Space is hard."
Outgassing of materials in vacuum may be a tough problem, but the properties of vacuum itself are behind an even greater challenge: heat.
Spacecraft heat up due to external energy deposition (e.g., solar or energy weapon), internal power generation (or use), and engine operation. Of the three main methods to shed heat, only radiation (emission of thermal energy as electromagnetic waves) is available. Unfortunately, radiating thermal energy is by far the least efficient of the three major mechanisms in removing heat. (Note 8) Space may be cold, but shedding heat to it is slow. (Note 9)
To illustrate the challenge, consider the International Space Station (ISS), which has no significant internal power sources. Instead, it relies on solar panels, which intercept some of the sun's rays, while the Earth itself sometimes shades it more. Nonetheless, the combined inputs of sunlight, internal electrical use, and the humans aboard require significant heat shedding. As stated by NASA:
The Station's outstretched radiators are made of honeycomb aluminum panels. There are 14 panels, each measuring 6 by 10 feet (1.8 by 3 meters), for a total of 1680 square feet (156 square meters) of ammonia-tubing-filled heat exchange area. Compare that majestic radiator with the 3-square-foot grid of coils found in typical home air conditioners and you can begin to appreciate the scope and challenge of doing "routine" things in space. (Note 10)
Operating lights, life support, sensors, and various scientific instruments at distances too far from the sun for solar panels to provide adequate power would require generating power internally. One such craft was proposed for the Jupiter Icy Moons Orbiter (JIMO) mission, intended to survey the moons of Jupiter.
Jupiter Icy Moons Orbiter
The JIMO spacecraft would have been powered not by solar panels, but by a 200 kW(e) nuclear reactor. Note that this is one fifth of one megawatt; commercial power reactors typically run over one thousand megawatts. As can be seen in the image above, the reactor is hardly more than a tiny dot at the tip, while the rest of the vehicle is mostly radiators. Per NASA, the radiator surface area was to be nearly three times that on the ISS. (Note 11)
The radiator arrays themselves were comprised of state-of-the-art (2005) heat pipes which were a product of a targeted development and testing program. (Note 12) Heat pipes are passive heat transfer devices; this means that no additional power needs to be generated (and resulting heat to be shed) to operate them. Basically, they are closed tubes with one end at higher temperature and the other at a lower one. Internal fluid boils at the hot end, the vapor travels in the center section to the cold end where it condenses, and the fluid then wicks back to the hot end by capillary action along the pipe walls.
Heat Pipe (Cooling Device in Space Is Radiator Array)
Image Courtesy of Radian Thermal Products (Note 13)
A large cylindrical spaceship with its hull completely covered in such radiators could dissipate about three hundred fifty megawatts. (Note 14) There are other radiator concepts, such as the liquid droplet radiator (LDR), which hold the promise (mathematically) of significantly higher heat shedding capacity. However, LDRs would require powered pumps and specific, precise geometries, and have not yet been tested in space. Empirical data are needed to establish certain key parameters, including sublimation rates, mass loss rates, and thermal transfer. Among the questions that need to be answered: which fluids lose the least mass in operation, which geometries are most efficient, and how much heat do droplets simply transfer to other droplets in the streams? (Note 15)
The next challenge of space is radiation, with the two main constituents being solar and galactic cosmic radiation (GCR). (Note 16) The sun's contribution is mainly photonic or electromagnetic in nature (Note 17) and can be adequately shielded against. Even during solar flares, astronauts are relatively safe unless they are outside the ship when they are exposed.
GCR pervades all of space and is comprised of a spectrum of energetic charged atom fragments—ranging in mass from electrons and protons all the way up to uranium nuclei—that originated as part of distant supernovae. Earth's mass and electromagnetic field shield those on the surface from most GCR but, away from the planet, GCR is essentially impossible to completely shield against with current technology. In fact, when the heavier GCR particles impact hull, bulkheads, and other physical objects, they create a shower of charged particles that emerge on the other side of the barrier.
The GCR radiation level experienced by astronauts on the ISS is many times that at sea level on Earth. Away from Earth's shielding mass and magnetic field, the dose increases even more. The actual doses humans will experience during deep space missions remain somewhat unsettled, but the current consensus appears to be that a mission to Mars (including the expected planetary stay time) would likely exceed current (very conservative) NASA limits. (Note 18)
Radiation also affects both electronics and materials. The former requires shielding much like humans do. Many materials experience an increase in outgassing when exposed to radiation. This unfortunate synergy has effects that are significant enough to require testing programs all their own.
The final space challenge to be discussed is the lack of gravity, or zero-g. Humans evolved in Earth's gravitational field and experience several adverse physical reactions to its absence. These include inner ear issues, bone mass loss, edema, vision degradation, blood chemistry changes, and digestion difficulties. Many scientific studies have examined these effects, and mitigating measures have been developed to partially offset some of them, including on-board exercises with weights and tension straps. Perhaps the most significant study involved the one year stay aboard the ISS by one of two identical twins while the other remained on Earth as a scientific control. (Note 19)
Any further treatment of zero-g is beyond the scope of this article except for the following aspect. Absent artificial gravity handwavium or some not-yet-existing drug protocol, any ship intended for extended human occupancy where the crew is expected to operate at high efficiency with quick reflexes may need to include design features to provide at least some gravitylike environment. The method most commonly postulated is a rotational element that substitutes centripetal acceleration for that of gravity. (Note 20) It should be noted, however, that this solution has potential problems and has never been tested. (Note 21)
So, keeping all these challenges and difficulties in mind, what would the first armed, crewed spacecraft look like?
That is a trick question. The answer is the image below:
Salyut 3 (OPS-2) (Note 22)
Salyut 3 was launched on June 24, 1974, and was equipped with a 23 mm cannon. The cannon was fired at least once during the 213 days the craft was in orbit. (Note 23)
Potential, near-term ship-to-ship space weapons would appear to come in three categories:
1) Energy - basically lasers,
2) Bullets - any non-guided projectiles, and
3) Missiles - with guidance systems.
As discussed above, generating and shedding the waste heat associated with powerful beam-style weapons are essentially not feasible with current ship-suitable technology. A notable possible exception would use only pre-stored energy (e.g., battery or accelerated flywheel). That is, the ship would not generate the weapon’s power during the engagement, limiting heat to the firing itself. Reloading would probably not be possible in any tactically useful interval. Quite possibly, the weapons would be one-shots, due to internal component heat failures after firing. Repeating weapons would require a very large ship with lots of power generation.
Bullets would rarely be useful at any sort of range. If used, they would probably be multi-part projectiles that spread during flight. They might be hexagonal rods, solid polyhedrons, or other forms initially tightly packed into one solid. They might be accelerated by electrical power or some sort of energetic event (like cannon firing). Unless they were launched recoilless rifle style (rearward ejection of equal momentum material such as energetic propellant gas), any projectile firing would affect the speed and trajectory of the attacking vessel. Using electrical power would create the same problems as firing energy weapons, such that stored power might be the better choice.
Missiles are the probable weapon of choice for the near future. They need not add heat to the crewed craft, and could be deployed in a great variety of methods and designs.
For example, missiles could be ejected a considerable time before an engagement, and not energize their engines until quite far removed from the launch vehicle. Alternatively, large numbers of missiles could be controlled by a small crewed craft with a similar signature, operating independent of the parent warship. (Note 24)
Missiles might have powerful warheads, shaped warheads to power one-shot laser-type weapons, small warheads used to spread penetrators, or no warheads at all (simply using their high kinetic energy). They could have multiple independently targeting submunitions. In that design, each central missile would generate the approach vector, but actually be more a bus with numerous smaller missiles being shed or dispersed at one or more moments. This approach is conceptually similar to that of the CBU 97 munition. (Note 25)
Turning to defense, perhaps the most important elements involve intelligence. Detecting adversaries while remaining undetected can be a decisive advantage. Beyond simple detection, the more one can learn about an adversary, the greater the advantage. What is their vector? What type of craft? How armed and equipped? Also, is it a true ship, or is it a decoy?
Millions of words have been written on the subject of stealth in space (or inability to achieve it). Summarizing them fully is beyond the scope of this piece, but consider the following two points:
• Voyager 1 is far beyond Pluto but its tiny signal can be detected, but
• Chelyabinsk meteor was not detected until it entered the atmosphere.
In the first case, detectors knew where to look and the craft emitted energy in the form of a signal. In the second, detectors had no specific focus and the object had no energy signature. The significance of emitting detectable energy cannot be overstated.
Any crewed spaceship requires life support, and the waste heat generated needs to be shed. An internal pre-chilled heat sink could delay emissions, but not prevent them. (Note 26) A shroud could be interposed between the radiator and the detectors, but stealth by directional emissions would only be possible if the locations of all the enemy detectors were known. A robotic craft could have a lower energy footprint, but not a zero one unless all onboard hardware were depowered. As was discussed earlier, electric power use creates heat.
The point here is that any spacecraft uses energy during operation and will eventually be detected even if there is no engine operation. Space is big, but (in energy emission terms) it is quiet. The Chelyabinsk meteor remained undetected partly because it came "out of the sun" such that the solar energy emissions helped blind detectors. Space warships may always be detected, but they still gain significant advantages in intelligence when they detect the enemy first. (Note 27)
Another factor is that not all intelligence is equal, and comes in "levels." One simplistic version:
• Detection - basic location but object remains unknown
• Identification - parameters and major characteristics resolved
• Acquisition - information sufficient for targeting
Even if both combatants detect each other, having better intelligence or advancing the intelligence level sooner remains a potentially decisive advantage.
Complicating the matter further is that sensors can be active or passive. Ones that are active emit energy and may produce better intelligence. Their emitter platform, however, can be detected at much greater ranges than it can detect targets. Active sensors also use more energy, but both types use some, increasing the heat signature of the host platform.
One approach to deal with the perils of employing sensors is to deploy them on remote drone craft, or even on stations like asteroids. This is analogous to hunting for submarines by dropping sonobuoys in the water, either to listen passively or to emit active sonar pulses. Separating the sensor signal from the parent ship helps keep the vessel undetected, but each sensor platform would have limited duration.
The next aspect of space warship defense is dealing with enemy weapons.
Unpowered, bullet-type projectiles would be the toughest to detect but the easiest to evade. Small, random course changes would be simplest, but energy blooms from evasive thruster taps would refine target solutions for beam weapons and smarter incoming ordnance. Small vector changes are possible without heat generation, but generally involve ejecting mass (e.g., liquid hydrogen expelled as gas jets), which limits the extent and frequency of this tactic.
Beam weapons might be hardest to evade, but ship rotation would significantly spread (hence dilute) energy deposition. Reflective and ablative materials would reduce risk, as well. Absent immensely powerful weapons, the ranges of likely ship-to-ship engagements would appear to limit the effects as the beam spreads and weakens in intensity with the square of the distance. Meanwhile, the operation of any ship-borne energy weapons create huge targeting signatures on their own craft.
Missiles appear to present the toughest challenge even though their heat signatures while under acceleration would be easy to detect. Individually, they can be defeated (once detected) by counter-missiles, or even bullets. Missiles need not come singly, however. Additionally, as discussed above, missiles might well not need to impact or even get very close to a ship to inflict damage. The variety of possible attack methods further complicates the defense.
A central "bus" type missile would continue towards the target after releasing submunition missiles, with its high heat signature potentially masking the cold ones that it had transported. Those with one-shot laser-style warheads might detonate beyond normal intercept range, or possibly be programmed to detonate immediately prior to being intercepted by hot counter-missiles. Some might detonate early with EMP events to attack the target sensors, with others then lighting off active emitter and others poised to use that detection information. Still others might employ only passive heat sensors and would not activate their engines until very close to the target.
The targeted ship retains the significant advantages of shorter counter-missile flight duration (the missiles could be smaller, simpler, and carried in larger numbers), defense choices (bullets, lasers, counter-missiles), and time (detected enemy launch might enable evasion). Nonetheless, the most effective defense would be to induce the enemy to fire at the wrong target. Decoys good enough for that purpose are probably not possible, however, once an object applies thrust in the battlespace. Detection algorithms would calculate mass by comparing the vector change and the thrust energy, thus separating out ship from lighter decoy. One tactic might be to eject the crewed portion of a larger craft early in the engagement, supplement its onboard AIs remotely, with the intent to rejoin or proceed independently.
Perhaps the major conclusion to be drawn from all of the above is that space battles are complicated, and they might well be decided long before the weapons impact.
Above was presented the first deployed armed space vessel, a product of the former Soviet Union. What would the first feasible space warship design by one of the armed forces of the United States look like?
This is another trick question. The answer is the image below:
U.S. Air Force Orbital Battleship
Image Courtesy of William-Black (Note 28)
The Orion design would use nuclear shaped-charge bombs to push it. Most of the Project Orion (which ran from 1958 to 1965) efforts were associated with the Engineering sections, but there was also a small "Space Warfare Analysis" team comprised of three USAF junior officers (Note 29). Their efforts caught the attention of the most senior officers and resulted in the USAF proposing that Orion-style craft be fully funded—included preliminary designs such as the one in the image above—during the development of the 1962 Air Force Space Program. (Note 30)
Unfortunately for space exploration, the Orion projects were all cancelled (for one thing, the atmospheric detonations would conflict with the 1963 Partial Nuclear Test Ban Treaty). That approach to ship design remains, however, the most feasible way to lift great mass from the Earth's surface into space, and then achieve high speed with large payloads anywhere within the Solar System. (Note 31) Orion remains a favorite of various space-interested on-line communities. There are many websites that feature Orion-type designs. (Note 32) The author's favorite is a video depicting how a battle between squadrons of Orion-class ships might play out in deep space! (Note 33)
Orion ships would have enough mass (over twenty times that of the entire ISS), lift, and endurance to be mission-flexible fighting craft, adaptable to many roles. Other types of space warships would probably need to be more specialized and "reverse engineered" from a designated mission. To have both endurance and tactical flexibility, they would need more fuel than they can likely carry into orbit.
Orions also launched in their mission configuration. Absent such immense mass and associated propulsion energy releases, optimum mission geometries in the vacuum of space would not be compatible with escape velocity through the atmosphere. For example, the JIMO probe would have launched in the "Stowed Spaceship" configuration (the image in the corner of the JIMO figure presented above). Then, resembling an insect emerging from its chrysalis, it would have unfolded origamilike into the mission configuration. A crewed space warship with enough ruggedness to survive acceleration and other battle stresses seems an unlikely candidate for that approach.
If Orions are ruled out, the above factors suggest (to this author) that any near-term deep-space warship would likely be built or assembled in space, or at a base on the smallest gravity well available: the Moon. If computer advances—including security—permitted, the craft would not be crewed. If humans were deemed required, the crew would be as few as practicable, consistent with the mission. The craft would have as many semi-autonomous, detachable sub-units as possible, each capable of executing various portions of the mission. These would include sensor platforms, missiles, anti-missile defenses, communication units, and any others that might require energy emission to operate. The vessel would depart with a pre-chilled heat sink and endeavor to keep it cold until arriving at the battlespace. At that time, the warship would minimize heat generation and shed it to the heat sink. The intent would be to detect the enemy first and gain actionable intelligence sooner.
In summary, the answer to the questions posed in this article's lead paragraph is to build Orions. If a deadly threat were detected inbound to our Solar System, whether it be elephant-looking aliens (Note 34) or a dinosaur-killer object, Orion-style ships would be the only craft of sufficient power and range to get significant mass out into space to deal with the threat well beyond Earth orbit. Some of the designs even resemble the ones in that second image at the start of this article!
2) Apollo 8 was the first crewed craft to leave Earth's orbit and travel to another destination: the Moon. The vehicle that actually arrived at the Moon for the landing Mission (Apollo 11) consisted of the command module, the service module, and the lunar lander module (the process or rotating and reconnecting the lunar landing module is shown in progress in the drawing).
3) Air resistance requires higher thrust to attain any speed and constant thrust to maintain it, raising fuel requirements enormously. Any gas pressure would also impose a maximum speed due to hull heating. For example, spacecraft atmospheric reentry burn up concerns are significant.
4) Some metal surfaces can benefit from vacuum (greater fatigue cycle life) due to evaporation of surface oxygen that could otherwise move into cracks and promote crack growth. These potentially beneficial aspects are, unfortunately, both few and minor compared to the many negative ones.
5) Non-U.S. scientific bodies (e.g., European laboratories) also use the terms "adhesion" or "stiction."
7) One example of the vast investments required was what was built to test full scale rocket engines operating at full thrust in a vacuum. See the two links below:
8) The other two major methods to transfer heat—convection and conduction—require direct contact with other matter. Astronauts do not have enough surface area to radiate away their body heat, so their suits use a fourth method during spacewalks: sublimation. Their suits evaporate one pound of water every hour they space-walk and release it to space. The constant loss of mass makes this method impractical on any larger scale. Additionally, it costs about $10,000 to lift each pound up to Earth orbit.
9) Which is why vacuum thermoses are so effective in keeping hot contents hot, and cold contents cold. For those wishing more mathematical treatments, the terms "black body radiation," Planck's Law," and "Stefan–Boltzmann's Law" are excellent research entry points.
10) From, "Staying Cool on the ISS," at NASA.gov.
11) Per NASA, JIMO was to have a 200 kW(e) reactor and 422 square meters of radiators (compared with 156 square meters of the ISS). This is roughly 2000 square meters of radiators per megawatt.
12) The heat pipe concept was proposed by several individuals over the years but the modern version was theorized (and patent filed in 1963) by George Grover at Los Alamos Laboratories, who noted that it would be useful in space applications. NASA developed the technology for satellites, where its success in zero-g led to expanded use. Heat pipes are ubiquitous today, especially in computers and smart phones.
13) A great variety of heat pipes and other thermal solution products can be found at:
14) A cylinder 1000 meters long and 200 meters in diameter has a surface area of about 700,000 square meters. Dividing total surface area by 2000 meters per megawatt yields 350 megawatts-electric. Note that this assumes waste heat can be moved hundreds of meters to the radiators without generating additional heat; that the reactor (or other power source) operates at about the JIMO design efficiency (twenty per cent); and that heat pipes can be built to function over lengths far beyond the current limit of a few meters. It's these sorts of numbers that drive SF writers wanting stories populated by ships with gigawatt power plants and terawatt lasers (let alone petawatt!) to handwavium.
15) It should be noted that any droplets that “escaped” would become potential micro-meteors, with all those attendant risks.
16) A third source of radiation emanates from Earth's Van Allen Belt, but this would not apply to craft while operating either in low orbit or sufficiently away from the planet.
17) During relatively rare solar coronal mass ejection events, protons can be swept up by the solar flare and accelerated out into space, thus adding significantly to dose.
18) Radiation levels vary by solar activity, and solar fluence changes cause the opposite change in GCR levels! That is, a Solar Minimum will decrease radiation levels from the sun, but that very drop in the solar wind will allow greater GCR levels. This means space missions have to consult the weather forecast—space weather! Shielding geometries and thicknesses are still being explored and tested, including multiple thin layers (sandwich style) of different materials. Space is not only hard, it's also complicated!
19) For more information, see the two links below:
20) Perhaps the most famous examples of substituting rotation for gravity are the station and ship in the classic movie, 2001: A Space Odyssey. Another approach might be constant, low thrust such as an ion engine might provide. This might be sufficient, but also remains untested and also would seem impractical for a warship trying to avoid detection.
21) For a good discussion of this and other related issues, see the following article by neuroscientist Rob Hampson (writing under the pen name "Tedd Roberts"):
22) The Salyut 3 image appears to be a colorized drawing similar to the one that can be found on the Wikipedia site, in Public Domain. The same image was once credited to a former USSR facility that replied to the author's inquiries that they have no knowledge of the image.
23) One of the cosmonauts discussed his experiences while he had been aboard in the video below. The gun firing portion begins at about 4:12.
An article devoted entirely to the gun itself:
24) The single-crew "pinnace" controlling a missile swarm approach is used extensively in the excellent Praxis series, by Walter Jon Williams.
25) The video at the following link depicts the CBU 97 and also shows the munition being field tested:
26) A case can be made to include a double-walled hull in the design, and to fill it with heat sink material, possibly an ice-water slurry. It might also add to radiation shielding.
27) Asteroid 2017 OO1—maybe twice or three times the size of the Chelyabinsk meteor—was not detected until about three days after it passed within about seventy-thousand miles of Earth. No energy emissions again, but it was detected. It simply took longer, but any delay could be critical in a space battle.
28) William-Black is the on-line name used by a very talented graphics art professional with a long interest in the Orion project. His work, including many more Orion images, can be found in the galleries at:
In particular, the author suggests these images:
29) Lieutenant Ron Prater and Captains Don Mixon and Fred Gorschboth.
30) For more on this, see the following article by Dr. Brent Ziarnick and Peter Garrison:
Dr. Ziarnick also gave a broader presentation on this subject at the science-focused Tennessee Valley Interstellar Workshop (TVIW)—attended by the author. All TVIW materials and presentations can be accessed through the main website here:
Dr. Ziarnick's presentation can be viewed in its entirety here:
31) The Air Force Office of Scientific Research symposiums on "Advanced Propulsion Concepts" explore various potential space systems. The Fourth Symposium (April 1965) considered the Orion-style approach in detail, including many technical areas and potential missions. See:
32) Two such links:
34) Footfall, by Larry Niven
Copyright © 2019 Jim Beall
This is part two of a series by Jim Beall on warships past, present, and future. Part one can be found here. Jim Beall (BS-Math, MBA, PE) has been a nuclear engineer for over forty years, a war gamer for over fifty, and an avid reader of science fiction for even longer. His experience in nuclear engineering and power systems began as a naval officer. Experience after the USN includes design, construction, inspection, enforcement, and assessment with a nuclear utility, an architect engineering firm, and the U.S. Nuclear Regulatory Commission (USNRC).