Retro Review: "Spawn of the Stars" (Charles Willard Diffin, 1930)

Introduction:

This is an alien invasion story, and an especially pure example of the genre.  Much of the science is dated, but the style is clear and the plot enjoyable.  Of additional interest, "Spawn of the Stars" appears to be a particularly seminal story, from which several alien invasion tropes famous from the movies of the 1950's and afterward, and even some which have entered the popular culture, seem to have originated.

Overview:

Viewpoint:  Third person, limited to Cyrus Thurston.  The only exception is that we hear of some scenes in montage, but they are very obviously being described by Thurston based on news he is getting from others.  We do not know anything that Thurston did not know himself.  This works well because Thurston is at some of the key points of the war, and is well enough educated that he understands a lot both of the military and of the engineering matters.

Style:  Direct, smooth and rapid, relatively unadorned with adjectives.  The only exception is in some of the descriptions of the aliens themselves, where detailed description is necessary in order both to convey information and mood.  This was not uncommon in the pulps, which were influenced both by Hemingway and by an overall journalistic technique.  Diffin was a clear communicator and a skilled writer, and the style helps carry rather than impending the tale.

Setting:  A contemporary or near-future Earth, c. 1930.  The aliens invade the entire world but we are limited to the main character's POV, and hence only see them attack parts of the United States of America, especially New York City and various West Coast cities.  Some detail is given of battles over Germany (Berlin is wiped out) and of alien activity over China.

Theme:  We live in a dangerous Universe, and the Spawn of the Stars may at any time descend and attack us:  fortunately, through courage and intellect, Man may triumph.  This is a common theme in alien invasion stories, and it is handled well here through use of characters to personify them:  Thurston is the viewpoint with whom we identify; Riley is raw Courage; MacGregor cool Intellect.  This is a "Power Trio", similar in structure to that of Kirk, McCoy and Spock from Star Trek: TOS.

Characters:

Cyrus R. Thurston:  A young man, presumably in his 20's.  He's a "millionaire sportsman," which means that he's a rich man who decides to excel in sports, not that he has become a millionaire through playing sports.  He appears to be too young to have served in the Great War,  Cyrus is an air enthusiast and owns and operates at least one private airplane.  Cyrus is well-educated, socially-prominent, brave and passionate.

"Slim" Riley:   Thornton's pilot, a veteran of air combat in the Great War, and thus presumably in his 30's.  Slim is "Irish" (which in context probably means "Irish-American"), brave, intelligent, highly-skilled and a bit fatalistic (in part due to seeing so many of his comrades fall in the Great War).  Though Slim is technically Thurston's employee, the two are clearly good friends.  His heroic sacrifice wins the war for Mankind.

The Secretary of War:  Never named, if the story takes place in 1930 then he would be Patrick Jay Hurley, President Herbert Hoover's second Secretary of War, a proud, honorable and well-educated man who served in the Great War and was a diplomat and mining magnate in peacetime.  However, Diffin probably wrote the story in 1929, and hence he might have been thinking of James William Good, President Hoover's first Secretary of War, who died suddenly of a ruptured appendix on November 18th, 1929.

The Secretary of War shown in the story is a brave, active man who is at first willing to believe that the aliens may be friendly:  an enlightened opinion for 1930.  When he finds out that the aliens are hostile, he is willing to hazard his own life to scout out the situation.  This description fits Hurley better than it does Good.  Hurley would have been only 47 at the time of the alien attack, and thus physically able to participate in the adventure.  He is slightly injured in the Battle of San Diego, but survives the story.

General Lozier:  An intelligent and forward-thinking military officer, knowledgable in scientific and engineering matters.  He leads the fact-finding mission to and gets caught up and killed in the Battle of San Diego -- unfortunately, since he was clearly a very competent leader.

Doctor Mac Gregor:  A brilliant and fearless scientist from the US Bureau of Standards.  He is sent to San Diego, observes the alien attack, and leads the recovery of the wrecked alien flyer.  Dr. Mac Gregor figures out how the alien engines and bombs work, discovers their key vulnerability, and develops it into a weapon.  He dies testing out his weapon on an alien bomb.

President Not Appearing in this Story:  Interestingly, one person we do not see in this story is the President of the United States of America, who in this period would be Herbert Hoover.  Historically, Hoover was a dynamic, progressive leader with a background in engineering, whose misfortune it was to be overwhelmed by a Depression of unprecedented magnitude, and it is improbable that he would have sat supinely and merely watched a crisis of this magnitude.  His absence in the story is probably due to the trope of the Invisible President, which was if anything much stronger in the 1920's and early 1930's than it is today:  in part because, before FDR's Fireside Chats, most people did not get to hear the President speak on anything like a regular basis.  We may logically assume that much of what was happening above Cyrus Thurston's level of involvement was being coordinated by President Hoover.

Plot:  Millionaire sportsman Cyrus R. Thurston is flying west across the United States on a whim, with his pilot and friend Slim Riley.  They are forced down by engine trouble (which may or may not be a coincidence, though the aliens at no other point demonstrate the ability to cause engines to misfire) and happen to land near an alien spaceship (1).  They see an alien on the ground.  The alien ship takes off, and they discover a cow which the alien has partially consumed (2).

Reaching Los Angeles, they are sitting in their hotel room wondering whether what they saw was real or a mere nightmare, when they read the newspapers and discover that the skyspheres have been sighted all over the world.  Now certain that what he saw was real, Thurston decides to go to the government with his eyewitness experience of the aliens.

Thurston and Riley fly to Washington, DC, where Thurston's social prominence gets him an interview with the Secretary of War.  The Secretary believes Thurston, and asks Thurston and Riley to accompany him and General Lozier and MacGregor, a scientist from the Bureau of Standards, to the West Coast, where the ships have just destroyed Vancouver in a series of  tremendous fiery explosions from their main drives, and are working their way southward.  The men fly west.

The Spawn scout out Seattle and San Francisco, but do not attack again as our heroes race west and US forces get into position to bring them to battle.  The aliens and the Secretary's party reach San Diego around the same time.  The Spawn destroy San Diego with a single tiny bomb that yields a kilotons-range explosion, and the battle is on.

The Secretary's plane is badly damaged in that tremendous explosion:  General Lozier and the Government pilot are slain.  Slim Riley lands the cripple as US forces go into action.  The US Army Air Force, reinforced by two US Navy aircraft carriers, and supported by anti-aircraft artillery, launches an attack.

The American attack is wholly ineffectual.  The alien weapons smash the carriers to burning hulks, swat the airplanes out of the sky.  The anti-aircraft guns appear unable to hit the fast, agile alien flyers.  At the end of the day San Diego lies in ruins and American airpower has been greatly reduced.

That night our heroes are resting in a ruined building when the word comes:  one of the five skyspheres is coming back!  They wait in fear and then spot the thing -- but its flight is clumsy. It's been badly damaged.  They follow the flyer in a car as it crash-lands nearby! (3)

Piling out, they see the monstrous alien pilot ooze from the ship.  Thurston, moved by wrath at the murder of San Diego and xenophobic hatred of the inhuman Spawn, attacks it with a handgun -- to no avail, as the amorphous alien is not harmed by the small slugs.  Dr. MacGregor realizes that the alien may be vulnerable to light, and drives it back with a flashlight.  Before the alien can get back to its sphere, the sun rises, destroying the monster.

Thurston and MacGregor investigate the crashed skysphere and discover that the Spawn technology seems to be based on ultra-compressed hydrogen and its chemical reactions.  They manage to salvage one of the bombs, and scientists investigate the wrecked skysphere.

The Spawn, in their four remaining skyspheres, strike Germany and destroy Berlin.  They are now massing against New York.  Slim Riley recovers from the wounds he suffered in the air crash, and Dr. MacGregor develops a ray which he believes will be able to penetrate the skysphere hulls and slay the Spawn by means of the same vulnerability they showed to sunlight.  Unfortunately, the scatter of (gamma?) rays from the projector will doom any human using the ray to a slow and horrible death (presumably either by radiation sickness or cancer). (4)

MacGregor tests his ray to see if it will detonate an alien bomb.  Unfortunately he miscalculates and is smothered in the sudden release of hydrogen (5).  Fortunately, he leaves his notes and plans for building a MacGregor Ray projector, and the US Army rapidly installs such a projector on a fighter plane.  Slim Riley, torn by survivor's guilt over both the Great War and San Diego, volunteers to fly it, despite the likelihood of a horrible death from the radiation.

The Spawn attack New York City.  Their bombs begin blasting the great metropolis, as Slim Riley rises to meet it in his ray-armed fighter.  The aliens at first do not realize the threat, until Riley launches his attack, in swift succession irradiating three of the four skyspheres.  The last one, now alerted to the peril, tries to escape, but Riley attacks it from below, hitting its bombs with the death ray (6).  Riley and the last skysphere are both destroyed in the resultant colossal explosion

On the ground, Thurston sobs in mingled relief and sorrow.  He, the city, and the Earth have been saved, but at the cost of the life of his friend.  But at least, as Thurston realizes, Riley died well:

Cyrus Thurston, millionaire sportsman, sank slowly, numbly to the roof of the Equitable Building that still stood. And New York was still there ... and the whole world....

He sobbed weakly, brokenly. Through his dazed brain flashed a sudden, mind-saving thought. He laughed foolishly through his sobs.

"And you said he'd die horribly, Mac, a horrible death." His head dropped upon his arms, unconscious—and safe—with the rest of humanity.

ending the tale.

Analysis:

The Aliens:  These are amorphous horrors,

Its blinding whiteness made the more loathsome the sickening yellow of the flabby flowing thing that writhed frantically in the glare. It was formless, shapeless, a heaving mound of nauseous matter. Yet even in its agonized writhing distortions they sensed the beating pulsations that marked it a living thing.

There were unending ripplings crossing and recrossing through the convolutions. To Thurston there was suddenly a sickening likeness: the thing was a brain from a gigantic skull—it was naked—was suffering....

The thing poured itself across the sand. Before the staring gaze of the speechless men an excrescence appeared—a thick bulb on the mass—that protruded itself into a tentacle. At the end there grew instantly a hooked hand. It reached for the black opening in the great shell, found it, and the whole loathsome shapelessness poured itself up and through the hole.

Only at the last was it still. In the dark opening the last slippery mass held quiet for endless seconds. It formed, as they watched, to a head—frightful—menacing. Eyes appeared in the head; eyes flat and round and black save for a cross slit in each; eyes that stared horribly and unchangingly into theirs. Below them a gaping mouth opened and closed.... The head melted—was gone....

with the power, as detailed above, to form and reabsorb temporary organs.  The similarity to one of H. P. Lovecraft's shoggoths is clear, and indeed so clear that I immediately wondered if Lovecraft got the idea for his shoggoths from Diffin's invaders.

As most of you probably know, the first detailed description of a shoggoth comes from Lovecraft's novella At the Mountains of Madness, written in 1930-31 and published in 1936.  In other words, written right after Diffin's story was published, at a time when Lovecraft, a voracious reader, would still have had the tale fresh in his mind.  However, shoggoths were also mentioned in "Night-Gaunts," sonnnet XX from Lovecraft's  Fungi from Yuggoth, written 1929-30 and published as individual sonnets in various fantastic fiction magazines, especially Weird Tales.  They were not, however, described in detail in the poem, and I now believe that Lovecraft may have been inspired by Diffin's creation.

Of course, the concept of an amorphous horror ultimately derives from a unicellular protozoan animal, the amoeba, which famously feeds by forming temporary "arms" (pseudopods) "mouth" and "stomach" (vacuole) to grab, engulf and digest its tiny prey.  However, amoebae do not form complex temporary organs, nor are they particularly intelligent.  The concept of a race of sapient giant amoeboids seems to derive from Lovecraft by way of Diffin, with Diffin's aliens coming chronologically first, but Lovecraft's being far more influential due to the greater popularity of At the Mountains of Madness.

E. E. "Doc" Smith's Eddorians can basically be described as super-intelligent, super-scientific and super-psionic shoggoths:  they are truly nightmarish creatures, and their first appearance in the original version of the "Lensman" series was in 1947, which was a decade after the publication of At the Mountains of Madness.  Smith probably had them in mind from the beginning of his series, however, the first part (Galactic Patrol) of which was published in 1937-1938 (7).

We never really learn all that much about the Spawn of the Stars.  We know that they are bigger and stronger than humans; they may also be smarter, or at least better at multi-tasking, because the invasion consists of five ships, each operated by one alien -- in other words, the whole human race is being attacked by the equivalent of a single flight of aircraft.  This is, and is meant to be, humbling.  One of the points of the story is the importance of superior technology in warfare, and the superior technology of the aliens allows a mere five of them to level Mankind's cities and swat our air forces out of the skies with terrible ease.

The aliens definitely have a more flexible biology than ours:  their natural atmosphere appears to be hydrogen-rich, yet they breathe ours without difficulty, and the fact that they eat Earthly cattle implies that their basic biology is not that dissimilar to our own (8).  Their brains appear to be dispersed through their whole bodies, and they can form and reabsorb their temporary organs with considerable speed.  Despite their size, they can move rapidly.  They have one great weakness:  strong light, in the optical and higher frequencies, rapidly disrupts their life processes and decomposes their tissues:  even a flashlight is "like the touch of hot iron to human flesh," a Very flare causes them to flee in terror, and, as for direct sunlight:

Incredible in the concealment of night, the vast protoplasmic pod was doubly so in the glare of day. But it was there before them, not a hundred feet distant. And it boiled in vast tortured convulsions. The clean sunshine struck it, and the mass heaved itself into the air in a nauseous eruption, then fell limply to the earth.

The yellow membrane turned paler. Once more the staring black eyes formed to turn hopelessly toward the sheltering globe. Then the bulk flattened out on the sand. It was a jellylike mound, through which trembled endless quivering palpitations.

The sun struck hot, and before the eyes of the watching, speechless men was a sickening, horrible sight—a festering mass of corruption.

The sickening yellow was liquid. It seethed and bubbled with liberated gases; it decomposed to purplish fluid streams. A breath of wind blew in their direction. The stench from the hideous pool was overpowering, unbearable. Their heads swam in the evil breath....

Armed with this evidence, plus the fact that their energy and explosives technology seems to be based on a supercompressed form of metallic hydrogen, it seems obvious from an early 21st-century point of view that the Spawn originate from the atmosphere of a large gas giant, such as Jupiter or Saturn.  They evolved below the visible cloud cover and above the metallic hydrogen ocean:  at home they would probably spread out into vast balloon or airfoil shape ("puffed shoggoths" indeed) and float or fly through their skies, forming temporary tentacles to secure prey.

It's a beautiful concept, and part of the beauty of this concept is that, though it makes perfect sense, it wouldn't have occurred to Diffin.  He wasn't stupid or ignorant -- it's just that in the 1920's, astronomers (there were as yet no "planetologists") assumed that the gas giants were pretty much terrestrial planets writ large, complete with abrupt transititons between "air" and "land," and with "oceans" properly confined to "seabeds," thank you very much.  Our current view of their atmospheres as slowly thickening into metallic-hydrogen slush and then hydrospheres, which in turn slowly thicken into increasingly-silaceous "mud" and then lithospheres, would astonish them.  But it is perfectly consistent with the physical nature of the Spawn as shown in the story.

We know absolutely nothing about the aliens' culture or motives for attacking Mankind, which is what makes this such a "pure" alien invasion story:  there are aliens, and they invade the Earth, period.  Thurston considers them evil, but then as a human under unprovoked attack, this is reasonable.  What's less reasonable is that he considers them evil the moment he sees them, based apparently on the alienness of their shape alone, before they've done anything hostile, to his knowledge, beyond eating cattle.  This could be marked down to third-person limited narration (all we see of the story world is what Thurston sees, all the opinions we get are what he either thinks or hears), except that Diffin obviously means Thurston's opinion of the aliens to be perfectly reasonable, and of course Thurston is right:  the aliens attack humanity without any discernable provocation or claim of need.

What one needs to remember was that, in the world of 1930, this sort of shape-based xenophobia was assumed to be normal, rational and sane.  Part of the reason was that the very concept of "alien life" was still new, and it was generally believed that most alien life (at least, alien life "like ourselves") would be very humanoid in shape.  This was more than just sentiment:  the evolutionary theory of the day imagined that the human form constituted something like perfection for a sapient being, so any very non-humanoid alien would have to be either "imperfect" or a very different kind of "sapience." 

One should add to this the assumption that different species would "necessarily" have to engage in a violent struggle for habitat:  the evolutionary biology of the 1920's barely acknowledged symbiosis or commensalism of any sort.  There were predators and prey, parasites and hosts, and that was pretty much that, especially in the popular-science variety of evolution.  So, if Spawn from the Stars suddenly appeared, it would logically follow that they wanted our habitat and, being super-scientific and hence unsentimental about such things (unlike we weak religious-morality-influenced men of the 20th century) would proceed to our extermination, forthwith.  This was also, note, the underlying concept of H. G. Wells' War of the Worlds.

This was about to change.  In none other than Lovecraft's At the Mountains of Madness (mentioned before), the hero was to feel sympathy for the (very) physically-alien Elder Things, even while retaining his horror at the Shoggoths.  Stanley G. Weinbaum would introduce us to friendly (though still semi-humanoid) aliens in "A Martian Odyssey" and "Valley of Dreams" (both 1934).  And most significantly, E. E. "Doc" Smith depicted a peaceful, multi-racial interstellar Civilization in his Lensman stories, starting with Galactic Patrol, some of whose members were very non-humanoid indeed (9).

Skyspheres and Other Possible Spawn Spacecraft

The alien technology includes metallurgy, which allows them to build large, light but strong spherical skyships, which may also be spaceships or at least landers (10):

It was of metal, some forty feet across, its framework a maze of latticed struts. The central part was clear. Here in a wide, shallow pan the monster had rested. Below this was tubing, intricate coils, massive, heavy and strong. 

There was a surprising simplicity, an absence of complicated mechanism.

If the aliens are Jovians or Saturnians (as seems very possible), then they may have launched a (well-shielded) interplanetary cruiser from Callisto or Titan, which carried the five sky-spheres as auxiliary craft, and went into a fairly close orbit of the Earth.  From this orbit the ship could launch and retrieve the sky-spheres without their occupants suffering undue radiation exposure.  Some of the odder maneuvers of the sky-spheres would be perfectly explicable if we assume that their own descents and ascents had to be coordinated with the orbit of their mother cruiser.  Within Earth's Van Allen Belt magnetosphere (whose existence unknown to Diffin in 1930), the skyspheres and mothership alike would both be protected from Solar flares.

This would explain why the crippled skysphere stayed behind at San Diego, and why none of the other skyspheres rescued its pilot.  The skysphere may have been damaged to a point where it was unable to launch into orbit and rendezvous with the mothership:  this may not have been discovered for certain until the whole flight of skyspheres attempted return to orbit.  Once the other skyspheres had launched, a return to Earth would have been impossible until the mothership fell into an appropriate position on her next orbit.  Before this could  be arranged, Cyrus Thornton and MacGregor killed the pilot and captured his sphere, and the aliens decided not to throw more of their limited assets into a fight over their ruined auxiliary vessel.  The reason why the skysphere did not attempt to fly far from San Diego may have been that its fuel was close to exhaustion, and also that too great a geographical displacement would have rendered a rescue more difficult, or even impossible.

Supercompressed Hydrogen Technology

The alien engines and bombs both employ an interesting chemical technology which appears to concentrate energy at a level midway between what we think of chemical and nuclear reactions.  Essentially, the Spawn have developed a means of compressing hydrogen to and beyond the point of what we would term its liquid metallic phase.  The supercompressed hydrogen can then be released in a controlled fashion, expanding into ordinary diatomic hydrogen molecules, either to do work directly through its gas pressure (as used in the skyspheres' drives) or to mix with oxygen in the Earth's atmosphere and then be detonated as a thermobaric explosive (such as the US uses today in its fuel-air bombs).

The generator, with its tremendous braces to carry its thrust to the framework itself, filled most of the space.

As a main drive, the system is demonstrably efficient enough to enable a Spawn skysphere to hover and maneuver in the Earth's 1G field for hours at a time:  this compares favorably with the likely performance of a nuclear fusion "torch" drive, and the skysphere can do this running the drive "cold" (without igniting the hydrogen plume).  It should also be considered that the Spawn probably used a variant of their skysphere engines to reach escape velocity from their gas giant homeworld, which might have been from 0.886 G (if Uranus) to 2.528 G (if Jupiter).

 Some of the ribs were thicker, he noticed. Solid metal, as if they might carry great weights. Resting upon them were ranged numbers of objects. They were like eggs, slender, and inches in length. On some were . They worked through the shells on long slender rods. Each was threaded finely—an adjustable arm engaged the thread. Thurston called excitedly to the other.

"Here they are," he said. "Look! Here are the shells. Here's what blew us up!"

He pointed to the slim shafts with their little propellerlike fans. "Adjustable, see? Unwind in their fall ... set 'em for any length of travel ... fires the charge in the air. That's how they wiped out our air fleet."

There were others without the propellors; they had fins to hold them nose downward. On each nose was a small rounded cap.

"Detonators of some sort," said MacGregor. "We've got to have one. We must get it out quick; the tide's coming in."

As a thermobaric weapon, the detonation from a device small enough for a human to clasp his hands around the fuselage is enough to destroy the downtown of a moderate-sized city:  multiple bombs can devastate an entire moderate-sized city including the near suburbs.  This implies a yield in the single-kilotons range, and an efficiency considerably greater than that of an atomic fission weapon, though inferior to that of a fission-fusion or fission-fusion-fission explosive.  A Spawn thermobaric bomb is much more physically massive than one would imagine at a glance (the supercompressed hydrogen is denser than osmium), but the whole apparatus is far smaller and less massive, than, say, were the Hiroshima or Nagasaki bombs.  The detonation of Spawn thermobaric bombs do not appear to produce radiation hazards:  the reaction is probably entirely chemical.

A side effect of both the skysphere drives and thermobaric bombs is the release of immense quantities of the supercompressed hydrogen, producing suffocation of entities (such as ourselves) unable to breathe the gas, and a freezing cold (due to the gas expansion taking up heat) equivalent to that of Earth's Arctic or Antarctic regions.  An interesting aspect of the supercompressed hydrogen is that it is initially far denser than air and thus falls rather than rises in Earth's atmosphere, until it has expanded sufficiently to become lighter than air (as is normal for diatomic hydrogen under Earthly conditions).  The result is the saturation of a large volume of Earthly atmosphere with the gas, and a very complete mixture with the oxygen, which is ideal both for suffocation and detonation purposes.

The aliens would be unable to contain the immense pressures needed to maintain the supercompressed hydrogen in that phase aganist the relative vacuum of either space or even Earth atmosphere at sea level, were it not that the supercompressed hydrogen is actually stable, and the design of the containment vessels destablizes it as it exits.  As MacGregor discovered:

"Hydrogen," the physicist was stating. "Hydrogen—there's our starting point. A generator, obviously, forming the gas—from what? They couldn't compress it! They couldn't carry it or make it, not the volume that they evolved. But they did it, they did it!"

Close to the coils a dim light was glowing. It was a pin-point of radiance in the half-darkness about them. The two men bent closer.

"See," directed MacGregor, "it strikes on this mirror—bright metal and parabolic. It disperses the light, doesn't concentrate it! Ah! Here is another, and another. This one is bent—broken. They are adjustable. Hm! Micrometer accuracy for reducing the light. The last one could reflect through this slot. It's light that does it, Thurston, it's light that does it!"

"Does what?" Thurston had followed the other's analysis of the diffusion process. "The light that would finally reach that slot would be hardly perceptible."

"It's the agent," said MacGregor, "the activator—the catalyst! What does it strike upon? I must know—I must!"

...

"What is it that explodes? Nobody knows. We have opened the shell, working in the absolute blackness of a room a hundred feet underground. We found in it a powder—two powders, to be exact.

"They are mixed. One is finely divided, the other rather granular. Their specific gravity is enormous, beyond anything known to physical science unless it would be the hypothetical neutron masses we think are in certain stars. But this is not matter as we know matter; it is something new.

"Our theory is this: the hydrogen atom has been split, resolved into components, not of electrons and the proton centers, but held at some halfway point of decomposition. Matter composed only of neutrons would be heavy beyond belief. This fits the theory in that respect. But the point is this: When these solids are formed—they are dense—they represent in a cubic centimeter possibly a cubic mile of hydrogen gas under normal pressure. That's a guess, but it will give you the idea.

"Not compressed, you understand, but all the elements present in other than elemental form for the reconstruction of the atom ... for a million billions of atoms.

"Then the light strikes it. These dense solids become instantly a gas—miles of it held in that small space.

"There you have it: the gas, the explosion, the entire absence of heat—which is to say, its terrific cold—when it expands."

MacGregor's explanation is partially nonsensical given what we know today, and there is no particular reason to belive the obseved effects possible given real-world science, but there is also no particular reason to believe it impossible -- we have never been able to experiment with hydrogen under the extreme conditions of pressure and temperature to be found within the hydrospheres, let alone lithospheres, of gas giants.  And there is an easy way that this could be possible -- photons of the right wavelength could knock loose electrons from atoms arranged in metallic lattice structure, causing it to break down.  Real-world photoelectricity (and photography) operates through a similar process, though with far less violent consequences.

Another obvious question is why, given so much hydrogen, and presumably understanding the laws of physics at least as well as did 20th-century humans, the Spawn do not use in the obvious manner as a nuclear fusion fuel or explosive.  I think that the answer is to be found in their extreme vulnerability to hard radiation.  A deuterium-tritium fusion reaction, which is the easiest controlled reaction to induce, produces free neutrons which are not only directly damaging, but also render the reactor vessel or its surroundings radioactive.  Even humans would need to shield a DT fusion reactor installed in any crewed craft; for the radiation-sensitive Spawn, the required shielding might be prohibitively massive.

I get the impression that the Spawn do not bother much with tools for ordinary mechanical or perhaps even electrical purposes, as they can simply form from their malleable bodies organs to serve as wrenches, screwdrivers, test probes and the like.  Likewise, their control systems are simple, since their own bodies can be control levers, knobs, dials and other readouts as required -- thus the "extraordinary simplicity" of their skyspheres. 

However, there is one obvious weakness to such a design philosophy -- it becomes very hard to handle anything that one's own body cannot endure.  They would thus would be particularly handicapped in any attempt to build nuclear devices of any sort, since waldoes would be difficult for a race not generally used to making manipulators.  And of course, their fear of any kind of nuclear accident would far exceed our own.

It's true that the deuterium-trihelium reaction (D + He3) produces no free neutrons, and the very limited electromagnetic radiation (mostly no worse than actnic) would be easy for even the Spawn to handle given the interposition of any sort of metal shield.  But the DHe3 reaction also runs ten times hotter than the DT, and it would be difficult to start a nuclear fusion power technology with trihelium if one had not first gained some experience with tritium-based reactions.  Given that the Spawn have a perfectly adequate drive and bomb technology with their supercompressed hydrogen, they have little incentive to invest in such a hazardous (to them) technological course as nuclear fusion.

Strategy

The Spawn were of course overconfident, which is what doomed their invasion to failure.  They correctly realized that their skyspheres were invulnerable to the (small-caliber) guns carried by Earthly aircraft c. 1930, and that they were too fast for human ground-based artillery to target.  They however failed to grasp the "golden BB" theory, which is that an aircraft may be downed even by poorly-aimed fire in sufficient volume:  this is what did for the first skysphere Thurston and MacGregor then salvaged, and it gave humanity enough information to devise a weapon designed specifically to shoot down skyspheres.

Stop and consider the way in which the aliens would have had to achieve victory, given the tools at hand.  Obviously, they were aiming to destroy the human military and industrial capabilities through strategic bombardment, using what amounted to five fighter-bombers armed with racks of tactical kiloton-range bombs.  This would have necessitated first systematic probes against the human defenses, to locate the centers of human communication, defense, population and production; followed by the systematic bombing of these centers.

There is no way, unless they received significant reinforcement, that they would have been able to wipe out the human population, or even enough of it to render ground operations anything but very hazardous.  They were clearly aware of their own vulnerabilities to light and harder radiation, else they could not have crossed the dangerous environs of the Inner System to operate on Earth.  They could have seen from orbit that we had the technology to generate a lot of light (one of their objectives was probably to knock out our urban electrical generation capabilities, but they can't have been unaware that given our mastery of electricity we almost certainly also had portable batteries).  So they must have known that oozing about, even at night, in full view of any organized human resistance was close to suicidal.

Obviously, therefore, the aliens would have needed to first damage our industrial plant and heavy military assets (ships, artillery and vehicle parks, etc.) enough so that we lost the capability to rapidly intervene on the ground against a landing, then have a follow-up ground attack force secure an area in terrain enabling easy defense of a space-head against human counterattack.  We don't know enough about the aliens to be certain of their space-head requirements, but their large size, high metabolisms and vulnerability to light suggests that they would want to capture an island -- one large enough for herds of animals to victual them, and small enough that all humanity there could be slain.  Once they had sunk our navies and major merchant shipping, counterattack against an island would have been difficult for us, and the aliens as described could have functioned perfectly well in Earth's oceans (which might not have been that different from their gas giant atmospheric home), swimming through darkness to intercept amphibious attacks, or raiding the shoreline by night.

The aliens could probably wear survival suits (given their anatomy, probably elastic bags) designed to protect them from sunlight, using the same material they built their ships' viewports from as goggle-lenses through which their large, probably infra-red or microwave-radar sensitive eyes could peer at the inconceivably radiation-rich and hellishly solid environment in which the monstrously rigid "human" vermin pranced about just as if it were the cool and flowing skies of Home!  They might have fought human soldiers with their own superior strength, or more likely with super-scientific weapons, such as flamers or explosive grenades based off the same compressed metallic-hydrogen technology on which their engines and bombs operated.  The pilots of the skyspheres in the stories did not have such devices, but then the skyspheres were supposed to have been impossible for the humans to shoot down.

Of course, when the humans developed the radiation beam cannon, this would no longer have been a practical strategy:  their skyspheres and ground forces would now be vulnerable, and on the end of a long logistics tether.  The aliens aborted their invasion, returning home to think, plot and plan their inevitable return, to win the resources of the metal-rich planet obviously wasted on the hideous human creatures.  When will they strike again?

The Humans: 

One must start by recognizing the ways in which c. 1930 Earth was more primitive and less capable of defending from itself attack, especially from the air, than would be the Earth of today.  There were no nuclear missiles, or for that matter nuclear weapons or significant rocket weapons of any kind.  There was neither radar nor proximity fuses, which meant that anti-aircraft fire was incredibly inaccurate by modern standards.  A defender would be unaware of an enemy air attack until the enemy craft had been visually sighted.

Airbases had not yet developed any but the most limited methods of controlling the squadrons they launched:  radios were clumsy and unreliable, and had only recently been applied to anything as small as fighters.  Air combat doctrine was in its infancy -- squadron-based tactics were had only been invented within the last 15 years, and combat aircraft within the last 20.  The idea of controlling squadrons across a whole theater of operations from a central command room (the British "Fighter Command" system of World War II) would not appear for a decade in Our Time Line.

Aircraft carriers were rare, small by modern standards, and the capabilities of carrier-launched aircraft limited.  In particular, they had operational radii of no more than a few dozen to few hundred miles.  They would be of use primarily in a fight for a port city, as was the case in the Batle of San Diego.  Naval forces had even by World War II standards only very limited abilities to protect themselves against enemy air attack, as was discovered in that battle when the Spawn easily smashed two American carriers (and presumably sunk their escorts).

Combat aircraft were single-engined open-cockpit biplanes, limited to altitudes of a few miles and speeds of a couple of hundred of miles an hour, maximum.  They massed at most several tons, and were armed with .30 to .50-caliber machine guns or small iron bombs.  Built primarily of fabric over wooden or metal struts, they were very fragile.  Their fuel tanks had no self-sealing features, neither cockpit nor engines any armor, and almost any sort of damage could easily bring them down.

Gunsights were simple fixed crosshairs. which meant that one could not reliably hit a maneuvering target (such as a Spawn skysphere) at more than a few hundred yards.  The limited power of the .30 to .50-caliber bullets was, in the story, insufficient to penetrate the metal hulls of the skyspheres.  Aircraft cannon were technically possible, and heavy  (37mm+) aircraft cannon might even have penetrated the Spawn skyspheres, but such weapons had not yet actually been deployed.

Bombs were dropped by guesswork, which meant that they were incredibly inaccurate against anything smaller than a city or major building complex unless dropped from an altitude of a few hundred yards while flying straight and slow.  The chance of hitting a Spawn skysphere in midair with a ground attack bomb would have been very low (tetherered observaton balloons were successfully attacked with such weapons in the Great War, but those did not maneuver).  Air-to-air missiles would not be invented for a decade and a half.

This goes a long way toward explaining the Earthly vulnerability to the Spawn attacks.  Even the Earth of 1940, let alone 1945 or 1950, would have been able to defeat a mere five skyspheres fairly quickly, if they attacked any seriously-defended site.  Neither the Earth of 1930 nor 1950 would have been able to detect or engage an orbiting Spawn mothership, though we could do it today with anti-satellite weapons.  (Whether or not we could overcome its defenses is debatable, since the story mentions no such motherships, and I simply surmise them from the small size and limited facilities of the skyspheres).

We do develop one weapon which proves effective against the aliens, however:

The MacGregor Ray

"In Washington a plane is being prepared. I have given instructions through hours of phoning. They are working night and day. It will contain a huge generator for producing my ray. Nothing new! Just the product of our knowledge of radiant energy up to date. But the man who flies that plane will die—horribly. No time to experiment with protection. The rays will destroy him, though he may live a month.

In 1900, Paul Villard discovered and in 1903, Ernest Rutherford named gamma rays, which are electromagnetic radiation with frequences greater than 10 exahertz.  The first cyclotron was built by Ernest Lawrence at UC-Berkeley in 1932, which makes it perfectly plausible that a brilliant engineer might be able to rush one to a field application c. 1930.

It's not clear exactly what the MacGregor ray is or how it is produced, but the story implies that it is a high-frequency electromagnetic ray capable of penetrating the metal of the Spawn skyspheres.  The description would fit anything from high-frequency X-rays up.  Furthermore, the horrible death likely to be suffered by the operator due to the lack of time to experiment with protection implies that the radiation is being produced by some form of radioisotopes, possibly under compression (an anticipation of the method actually used to induce nuclear fission both in reactors and in bombs).  The shielding problem would stem from the need to install the weapon on a combat aircraft capable of catching the skyspheres:  obviously, thick lead would work, but as obviously would not be practical on a c. 1930 fighter plane.

An actual gamma-ray laser ("graser") or even x-ray laser would be highly unlikely given the technological limitations of 1930 (today we can just barely and in theory make a nuclear explosion-pumped x-ray laser).  It's more likely that we're talking about a sort of gamma-ray "flashlight," a weapon whose radiation at range would be far too puny to be a practical death-ray against humans (even the pilot, sitting right next to the ray, would only suffer radiation poisoning leading to eventual death), but is sufficient to slay the radiation-sensitive Spawn.

In time, Earthly engineers would be able to lick the blowback problem which caused radiation poisoning to the operator.  But the Earth didn't have the time.  Future Spawn invasions, however, will have to contend with the presence of MacGregor ray cannons in the hands of human defenders.  Perhaps this will be enough to deter them.  Perhaps ...

Musings and Speculations:

Alien Invasions

"Spawn of the Stars" is an utterly pure alien invasion tale.  We never learn where the aliens were from or what they want (other than to kill us).  They show up, they start killing us, and we must kill them first if humanity is to survive.  This is both a product of the racialist philosophies of the age, and a major virtue of the story -- nothing gets in the way of the threat and the need to solve the problem through the intelligent application of physical force.

Compare with War of the Worlds, in which the human race never does find a weapon against the Martians:  we are saved by pure dumb luck and the virulent diseases of our mother planet.  Or with Footfall (Larry Niven and Jerry Pournelle, 1985), in its own way as much a classic of the alien invasion genre as WotW, in which humanity does launch a warship capable of defeating the invaders, but this proves possible as much due to the limitations of the Fithp imagination and personality as due to the pluck and wit of Mankind.

Both War of the Worlds and "Spawn of the Stars" are far more frightening than is Footfall, Turtledove's Worldwar, or other more recent alien invasion novels, and the reason is simple.  We get to see things from the viewpoint of the Fithp and the Race, and indeed to sympathize with them (to some extent) (11).  By contrast, Wells' Martians and Diffin's Spawn are mysterious, implacable, and superhuman forces of destruction.  Their motives and nature are unknown, and the unknown is always more terrifying than the known.

As mentioned, Thurston's extreme xenophobia at sight of the Spawn's amorphous anatomy, which extends to a conviction that they are evilly intelligent, seems to be justified in the light of their later behavior.  The assumption here, from what I could tell, was that the alien was to be presumed hostile, and the more so if it was hideous to human eyes.  This assumption is identical to that of the early Lovecraft, though not of the later Lovecraft, and especially not to that of the later E. E. "Doc" Smith, who had extremely nonhumanoid heroes such as Worsel, Tregonsee and Nadreck, in the Galactic Patrol.

At no point does Thurston become aware of any attempt by either side to communicate with the other, and the impression I got from the tale was that, if we tried, we were probably ignored.  The science of the day took the Darwinian "struggle for existence" quite literally, and the science fiction of the day depicted this struggle as being carried out with super-scientific weapons between sapiences of different forms.  The culmination of these beliefs was, of course, the carnage of World War II, and the deaths of tens of millions at the hands of the Nazis and Communists.

Today, we tend to make more peaceful assumptions about sapient alien:  influential in this regard has been the books of Carl Sagan, who argued that aliens adavanced enough to engage in interstellar travel would have either culturally evolved past wars of aggression, or destroyed themselves with weapons of mass destruction.  Others still believe differently, particularly Charles Pellegrino and George Zebrowski, who in The Killing Star (1995) argued that alien civilizations would be inclined to mutual destruction owing to the fear that other (alien and hence unpredictable) beings would enter aggressive cultural phases and the desire to destroy such civilizations, before they could strike.

The true state of affairs is still unknown.  It may be closer to Sagan's vision, it may be closer to Pellegrino's.  Reason would argue in favor of some caution when dealing with alien sapience, and especially in regard to more advanced alien civilizations.

Air-Mindedness and Scientific Research

One thing that strikes me about the story is that it is remarkably air-minded for a tale penned in 1929.  Keep in mind that this was a time when the long-term military importance of airpower was far from established in the general culture.  The armies and navies of the world generally assumed that aircraft were at best scouts and light raiders, incapable of turning the tide of a battle save by providing intelligence or scoring lucky hits.

The military establishments of c. 1930 were far from committed to scientific research.  New weapons emerged pretty much at random from industry during peacetime, to be purchased or ignored by the armies and navies as the mood took them.  The concept of technological superiority being crucial to victory in wartime was not yet universally accepted.

The military component of "Spawn of the Stars" is almost entirely about airpower and military research.  The Spawn strike from the sky with bombs capable of sinking whole naval squadrons or demolishing whole cities.  Likewise, humanity must take to the skies to fight back.  The only warships worth mentioning are aircraft carriers; the only artillery are anti-aircraft guns.  The only land action shown is the salvage of a crashed skysphere (a scene that became standard to later science fiction) against the opposition of its pilot.  The strike that delivers final human victory is delivered by a modified fighter plane, and could not have been delivered at all from the ground.

This is very progressive for 1930.  It foreshadows in many respects the strategic air war of 1939-45, particularly the destruction of whole cities by incendiary and nuclear bombing in the last two years of the war.  It was of course in part inspired by the German air campaign against the British from 1914-18 (the brief mention of a zeppelin would have sounded sinister to a reader c. 1930, and the destruction of Berlin in the story could be seen as karmic payback by a contemporary reader), but takes place on a much grander scale and is far more crucial to the outcome of the war.

What Happened Next?

Observant readers may have noticed that the situation is far from resolved.  The five Spawn skyspheres which attacked the Earth have all been downed, but we have no idea from where the Spawn have come, whether this was merely the vanguard of their attack, or even if there are still more Spawn, either in orbit (12).  It is easily believable that the Spawn will strike again:  furthermore, one would imagine that humanity might be interested in exploiting the alien technology that they have captured and building spacecraft of their own.  Clearly, the awareness that we are not alone, and that our neighbors are hostile, will affect the future of the human world.

One wishes for a sequel.

Conclusion:

This is a fun story, well worth reading and re-reading, and one seminal to the whole alien invasion genre.  I am now going to seek out more of Diffin's work, and wonder why he hasn't been more noticed by anthologists reprinting early science fiction.

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Notes:

(1) - Ah, sweet Coincidence, the Muse without which so many pulp sf plots would utterly unravel!  On the other hand, we may assume that there were plenty of people who did not see an alien on the ground this early in the invasion:  it is in fact this encounter that makes the protagonist the protagonist, so it's not too jarring a coincidence.  The next coincidence will be one too many, though.

(2) - This is noteworthy as what is perhaps the first example of alien cattle mutilation in science fiction:  this may be the stem from which the whole concept sprang.  In this story the aliens are doing this to eat the cattle, which actually makes sense (granting compatible biologies):  it's much safer and easier for the aliens to kill and eat cattle (who can't fight back effectively) than it is for them to kill and eat humans (who can).

(3) - This is the really major coincidence of the story, and the least believable.  Why did the alien flyer come back?  If it was damaged in the Battle of San Diego, why did it stick around near human-habited areas for hours, rather than setting down in the wilderness to the east?  And wasn't it convenient that it came down so close to the heroes that they could follow it in a CAR? 

This is annoying, because Diffin could have as easily chosen to have it come down a hundred miles away, and had the heroes receive the report of this:  he chose coincidence just because he wanted to let us see the flyer crash.  In my opinion, it damages verisimilitude.

Perhaps I'm more sensitive to this than the original audience because, as someone who grew up with World War II air campaigns as part of the background, I'm aware of just how much distance a damaged fast subsonic aircraft can cover before it goes down.  Diffin and his audience were only personally familiar with the slow subsonic aircraft of the Great War, which you could have trailed in a (fast) car had the plane been damaged.

(4) - Radiation sickness was actually known as early as 1896, when Nikola Tesla intentionally exposed his fingers to X-rays to see what would happen.  Marie Curie, the most famous early victim of long-term radiation tissue damage, did not die until 1934.  It was not until 1945 and the scientific study of the aftereffects of radiation at Hiroshima and Nagasaki that people generally became aware of just how dangeorus can be hard radiation:  Diffin was being somewhat prophetic in realizing that the MacGregor Ray would be dangerous to humans as well as to the Spawn.

(5) - This death is biologically dubious (brief immersion in an unbreathable atmosphere wouldn't kill you any more than would brief immersion in water, and the supercompressed hydrogen would rapidly expand to ordinary diatomic hydrogen and rise into the air, restoring the oxygen to your environment).  It's also very obviously for the convenience of the plot, as otherwise MacGregor rather than Slim Riley would be flying the fighter plane at the end of the story.  And what's worse, it's unnecessary even for plot purposes:  had MacGregor instead set off a thermobaric explosion he might have quite plausibly been killed in the blast, and of course his messing-around with gamma radiation might well also have killed or at least crippled him.  It's one of the weakest elements of the story.

(6) - There is an obvious similarity here with the manner in which Russell Casse, also a traumatized war veteran fighter pilot, destroys one of the giant alien saucers in Independence Day.  I am not claiming that one was inspired by the other, because it's such an obvious plot element, but this may have been the first example of this particular kind of heroic sacrifice in science fiction.  For a different version of the same sort of thing, which may have inspired Diffin, consider the death ride of HMS Thunder Child in the novel War of the Worlds.

(7) - Triplanetary originally appeared in 1934, but the early version of this story covered only Gray Roger and the Nevian invasion:  it was not until the 1948 reprint that Triplanetary was retconned into the Lensman universe, with Gray Rogers being an incarnation of Gharlane of Eddore and the Triplanetary Patrol being the original form of the Galactic Patrol.

(8) - On the other hand, the fact that they eat whole HERDS of cattle may mean that they require certain nutrients which Earth life possesses only in very small quantities.  Though their shape-changing is probably metabolically-expensive, I would doubt that they would need to eat such vast quantities of their own kind of life.

(9) - Though it's interesting that all three named authors used amorphous aliens as villains.  Lovecraft never presents any even slightly sympathetic view of the Shoggoths, even though they were (by geologically-modern times) sapient slaves of the Elder Things  (for a sympathetic view of them, see Elizabeth Bear's "Shoggoths in Bloom").  Weinbaum's "doughpots," from "Parasite Planet," are non-sapient and eternally hungry -- about all one can do with them is incinerate them with flame-pistols.  And the far-too-sapient Eddorians are the source of all evil in the Lensman universe.  Humans just don't like giant blobs -- it seems ingrained in us, for some reason that I can't wholly fathom (since we didn't evolve being preyed on by such creatures).

A thought -- maybe what we're really afraid of is not blobs, but bogs.  Virtually every fictional description I've read of being attacked by a giant blob emphasizes being smothered, even though logically in some cases, what one should be noticing is not so much "smothering" as being torn apart (by shoggoths) or burned by digestive acids.  Now, if one falls into quicksand, one is not torn apart or burned, but one is most definitely smothered.  And humans, as semi-aquatic apes, evolved in an environment containing far too many bogs ...

(10) - In the pre-dawn of the Space Age, aircraft, shuttles and spaceships all tended to be conflated, and we never learn whether the Spawn sky-spheres are operating from a secret base on Earth, a mothership in orbit, or are themselves capable of crossing interplanetary or even interstellar distances on their own.  The spheres as described might be capable of attaining and landing from Earth orbit; they seem a bit small and their engines a bit puny for flight across interstellar distances. 

One reason why they may not be capable of interstellar travel is that the aliens are vulnerable to, and the flyer hulls do not seem very resistant to, hard electromagnetic radiation.  Any alien interplanetary cruiser would have to be better shielded than those flyers, especially on a long flight.  Diffin would have been unaware of this problem, as human scientists did not in 1930 grasp the magnitude of hard radiation put out by the Sun, especially into the Inner Solar System.

(11) - The Fithp are indeed rather pathetic:  they're a race of domestic animals Uplifted to intelligence who have learned their advanced technology by rote from pillars left by their former masters.  They don't really understand the Universe or see the possibilities of technological innovation; the group of Fithp who invade the Earth do so from perceived necessity (they are refugees from the losing side of a war); and after the initial shock, humanity's superior intelligence and imagination enables us to quickly adapt to their weapons and tactics -- in the end, they wind up re-domesticated, by America.

The Race is not as pathetic but they are somewhat admirable:  they are convinced that their ancient, incredibly-conservative civilization, similar in some respects to a rather humane sort of Oriental despotism, is the only way for sapient races which they perceive as "barbarians" to live in peace and harmony.  They expect to find the Earth at an Iron-Age level of technology, and when they find us instead at a late-Industrial tech level are not really quite sure what to do next.  They unimaginatively proceed with their invasion as planned, and suffer horribly as we learn and adapt to their weapons and tactics, and in the end this leads to Earth developing a technology beyond that of, and probably dooming, their ancient empire.

Neither the Fithp nor the Race are as malevolent as the Martians or the Spawn.  The Fithp want to fight and then politically domiante us, while the Race wants to "civilize" us.  Neither wish to exterminate humanity nor even crush our civilization:  they want to rule rather than destroy.

(12) - The very notion of an orbital presence would not have occurred to most sf writers or readers of 1930, even though Tsiolovsky had come up with the notion of artificial satellites some 40 years earlier.  The very first stories to mention orbital space stations were being written around the same time as this, specifically Jack Williamson's "Prince of Space" (in which such a station is a plot element):  see my review of this tale.  But they could have been up there, and the rather sparse design of the skyspheres implies that they were.