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Hollow Moon Exploration: 3... 2... 1... LIFT OFF!

by Sharon Dornhoff

Luftkapitan Kauser's Log, AC 968, Heldannic Warbird "Adler":

Felmont 19 (Orbit) -- By the Grace of All-Conquering Vanya and by the Manifest Righteousness of our Purpose, success! Our vessel has taken orbit 'round Matera on this, the fifty-eighth day of our voyage across the Void. Come the dawn in Freiburg, the banner of the Knighthood will wave above the silvery hills and valleys of the moon! Already, Matera yields her secrets to Vanya's questers; her dark side, never yet seen by eyes of worthy Men, shall be revealed in all its vastness to us within the hour. What great unknowns will lie beneath us, upon this undiscovered country -- what untold realms to explore, what new lands to claim, for our Patron's greater glory...?

Felmont 19 (later) -- Strange world, this lunar landscape, and none so hospitable as the heathen Myoshimans' lands! No sooner did Adler's orbit bear us within close view of the daylight's terminator, than the fiery radiance of the far side's surface struck our lookout near-blind through her spyglass (Herr-Chaplain Straus will restore the Ensign's bedazzled vision, when next Our Lady Vanya favours him with new spells). I have ordered the sun-baffles, which served us so well in crossing the Void's glare, kept in place whenever Adler moves beyond the moon's shadow, and find I must limit our plans for exploration. Troublesome though the cold and darkness of the lunar night threatens to be -- and dearly as I would have relished being the first human, to behold the dark side! -- our enspelled hull will not retain its atmosphere for more than six score days; to linger the half-month necessary for Matera's hidden face to lie once more in shadow, would strand us here ... or worse, force us to shelter on Myoshima, where any cat-faced savage who learned of our doings might squall word to their Emperor. No flag but Vanya's Lion must ever fly upon lunar soils, least of all that of insubordinate subhumans! But I will not grieve, there will be other moonflights....

Felmont 20 (Touchdown, Nearside, foothills of the Cordilleras) -- Wonders upon wonders, but a bitter disappointment above all. This world is not habitable to human folk. Matera's Skyshield grips as do other worlds', yet as divinations implied (would that we had interpreted them more truly!), she clasps no breathable air unto her surface. Bereft of a warming atmosphere, the blood-freezing chill of this drab, rock-and-dust wasteland is beyond imagining; for all their hardiness, only the spells of our priestly personnel allow my crew to endure it. A strong breath, that carries vapour beyond our protective magics, falls frosted into snow before the next one! Our scouts are beset by troubles, for lack of landmarks or of stars in proper array, and have espied neither sign of water nor of living presences. We shall take samples of soil and rocks, in hopes this world may offer resources worth the having ... but I feel it in my bones that Vanya's Lion-Banner -- which, to my regret, hangs limp and listless for want of wind, though I have propped it to unfurl despite the lack -- gains little glory by the conquest of so barren and unpeopled a realm.

Felmont 24 (Sea of Rains) -- From rocky hills and crater-scarred wastes (Fools, all those who name these darker blights upon Matera "seas"!), we have crossed an open stretch of bedrock: an exposed, translucent crystal that seems almost to drink in Mystara's light. Our geologist, Herr Kaupf, has insisted we put down upon this flat, cheerless vacancy, that he might compare the bedrock's qualities with some curious shards of fragmented rock he gathered in the mountains, where first we landed. (The man has conceived some improbable theorem to account for those -- admittedly-weighty, and of a veritable razor's edge -- fragments; but his pleas that we return to those highlands, are as unreasonable as they are unseemly.) I grant, the stone on which the Adler perches at anchor is odd -- our strongest crewman's sledge, delivered with all his Vanya-given might, makes not a scratch, and Herr Kaupf has broken both his diamond headed picks with his puttering! -- but rocks that will not be broken cannot be mined. More and more, I brood that the Knighthood's efforts in this forsaken place are in vain: that it has naught but cold and dust to offer, to us or to our Patron.

Felmont 27 (Palus Somni, beyond the Sea of Tranquillity) -- Our lookout took sight of a faint glow within the crystalline ground, in the "Sea" just ahead*, and (rightly wary, now, of lunar light!) alerted the officers and I to this curiosity. The exposed bedrock now shimmers with a faint, deepest-blue radiance, visible to untrained eyes only when the Adler's lanterns are doused. Cautious, we alit upon the lowlands so as to investigate from a judicious distance -- no telling what fell magics might lie sleeping upon this dead world, for we know by now it is no meet place for men! Only upon landing did a humbler solution present itself; Herr Kaupf, in delving the soils and rubble at this new landing site, unearthed bits of quartz -- more crystals, but of a common stone this time -- which gleamed with an eldritch, moon-silvery luminescence. As single stones, these gemlets give but scant illumination, but a score gathered in the hand may easily suffice for reading-light. It would appear these lands have one gift, at least, to offer our Order and the Heldann Territories.

[* -- Mare Crisium]

Fyrmont 1 (Return journey) -- It is the month of fire, and never was its name more meaningful! As Adler took wing, the terminator of sunlight, which has rounded the far side to intercept us, crept over the last of our landing-sites. The sudden transition into sunlight left us sweating within the baffled hull, till we broke through the Skyshield; daylight temperatures are every bit as extreme as those of night, on Vanya's new world! And indeed, Matera WILL join the Heldann demesnes, for the luminous quartz Herr Kaupf has gleaned from her surface will spare the Order from squandering its tithes on torchlight, and free the brethren of the abbeys from their onus to illuminate our forts and vessels with spells. Six bushels of these exotic jewels lie safe in Adler's cargo hold, secured in taut iron coffers against the rigours of space travel. A worthy tribute they shall make, to Our Lady ... and a demonstration to every heathen foreigner that the Order prevails over all adversity and doubt. By the Grace of Vanya and for the Glory of Her Eternal Dominion, let all beings who gaze upon the moon by night know: Matera is ours!


Fortunately for the good Luftkapitan's ego, he never knew the truth: the Heldannic landing on Matera, though much-trumpeted by the hierarchy of the Knighthood, wasn't the first successful mission to the moon in Mystaran history. It wasn't even the second, third, or fourth! (Not so fortunately for Herr Kauser, he'll NEVER know: upon finding the vaunted coffers contained nothing but ordinary, dirt-grade quartz rubble, the Order's commanders stripped him of his rank and sentenced him to a life of hard labour.) In the preceding four millennia, the HKs had been beaten to their destination by Blackmoorian astronauts, Nithian pilgrims, curiosity-driven gnomes (ouch!), and venturesome Myoshiman tiger-riders... not to mention the elemental-earthen spirits know as "desert ghosts", who've dwelt there since almost the beginning of time.

The only thing that might have hurt Luftkapitan Kauser still more, would be to learn how very close he'd come to discovering the one remaining secret of the Mystara-Patera-Matera cluster's planetology: that Matera, like Mystara itself, is a "hollow world", home to races and species that have long since passed into extinction on their planet of origin. The Hollow World we know is a refuge for those races which thrive under Ixion's eternal sun, and for subterranean cultures that have burrowed their way entirely through Mystara's gravity-plane to arrive there. The Hollow Moon -- a world even less accessible, and even more cryptic, to daylight-races -- is a haven for doomed nocturnal species that cannot easily adapt to life underground, as the HWs Schattenalfen have. It is a realm where humans are, at best, a minor and disreputable race... where nomadic cryions cross "oceans" of frost-rimmed crystal that shines beneath their feet... where araneans and phanaton-kin are the best of allies... where grim mountain empires of kopru and pteryx loom over vibrant city-states of traders, tricksters, and thieves. It's a world where the dome of the heavens shimmers with an eerie blue glow half the month-long day, where coral reefs shine up from the depths of the seas like light-sculptures, and where eclipses really do cause disasters. Most importantly, it's a place that can keep on surprising your players with weirdness, even if they think they know the Known and Hollow Worlds and the Savage Baronies backwards and forwards.

But before we look inside the Hollow Moon, let's take a peek at Matera from the outside, as well as its IRL twin, Luna. First, some facts about the real-world moon, with comparisons of how it and Matera are similar; next, three significant ways in which Matera differs from its real-life counterpart; then some thoughts about D&D space travel and reconciling the HM setting with the Spelljammer and/or Voidship rules; and finally, a whole bunch of REALLY bizarre ways to get your PCs to Matera ... most of them from a wonderful book I discovered -- "Voyages To The Moon" by Marjorie Nicolson (too bad it's OOP, copyright 1948; it's worth reading, if you can find it!) -- while researching lunar exploration as it's portrayed in historical fiction.

Luna: the "real thing"

One of the first things to remember, about the moon -- whether you're talking about Luna or Matera -- is that, compared to Earth/Mystara, it is TINY. With a diameter of only 2160 miles, it's so small you can actually see its curvature falling away in the distance. If the Empire State Building were moved to the moon, it would disappear below the horizon if you walked more than 8 miles away from it. In the Hollow Moon setting, virtually the whole of the Nearside is habitable by one species or another; yet that's only about 1.8 million square miles of land, sea, and crystalbarrens, for the entire Nearward Hemisphere. The Alphatian Empire at its height, before the Thyatians broke free of its clutches, encompassed more than twice the land area of the Hollow Moon.

The second important fact about Luna and her OD&D counterpart, is that compared to Patera and the various artificial satellites Earth's humans have launched, they're VERY far from the planets they orbit: 238,600 miles! By comparison, the orbit proposed for Patera on Daniel Boese's Web page, "The Mystaran Moons", is a mere 34,200 miles... practically the house next door. Such distances should pose a mind-boggling challenge to any Voidship headed for Matera, using the CoM rules strictly as written, as even the fleetest of these vessels travels only 327 miles through the Void in 24 hours. (For Spelljammers capable of "warp speed", of course, it's a distinctly-undramatic four minute hop; but more on how to modify the spaceflight rules for a moon-visit, later.) This means that Luna travels slightly less than 1 1/2 million miles every month, at speeds of roughly 2300 mph; merely catching up to Matera, which moves with equal speed around Mystara, should prove nearly impossible for even the swiftest Warbirds or Alphatian airships, if their navigators neglect to plan ahead. (Sorry, Bruce, but I don't think the ol' Princess Ark will be stumbling upon this one by chance! ;-D)

The real-world Luna has an orbital period of 27.3 Earth days, during which it circles the Earth completely and experiences one lunar day. (The slower, 28-day lunar phase cycle we witness on Earth is partly an effect of our own planet's simultaneous movement.) Because of a "dragging" gravitational effect of its sister-moon Patera -- and for DM convenience -- Matera has a 28-day orbital period. Explorers on the Nearside are always able to see the Earth/Mystara, except on those dates when the moon in question is full (and hence, the sun is on the planet's opposite side). Visitors to the Farside of either moon had best carry accurate chronometers or spells to keep track of time, as no such cues to time's passage are visible in the Farward skies, and to be caught by the terminator -- the boundary line between dark and light which sweeps across the Nearside's surface each month, starting over the Mare Foecunditatus and disappearing beyond the Oceanus Procellarum -- can mean instant blindness or a fiery, UV-seared death.

Having no atmospheres, Luna and Matera are both alternately exposed to blistering, brilliant sunlight, and the icy chill of space. Visitors to the bright side of either moon must cope with "high noon" temperatures of up to 210 degrees F, as well as glare that can blind in microseconds and direct UV-rays which burn exposed skin just as fast. At the opposite extreme, the shadowed lunar surface gradually drops to -240 degrees F after sundown, with lunar bedrock temperatures rapidly equalising to -30 degrees at depths of 1 meter or more. Night on the moon's Nearside is surprisingly bright, as reflected sunlight from the (full or gibbous) Earth/Mystara sheds five times as much illumination to the lunar surface as the moon itself would shed, in similar phase; stars are also considerably brighter, and they do not twinkle in the absence of a screening atmosphere.

The axis of rotation of Luna is less steep than Earth's, lying almost perpendicular to the plane of the "ecliptic" -- the plane of Earth's orbit round the Sun. Thus, apart from lunar eclipses which temporarily cause surface temperatures to plunge, on an annual but irregular basis, there are no seasons on Luna. Matera, too, has none of the usual seasons for an Earth-like planet; however, near passes by its invisible sister-moon occur on a predictable basis, and affect HM weather and geological activity through Patera's tidal pull. None of these climatic influences can be felt, on the inert exterior of Matera.

Luna is a dead world, composed largely of basalt and interstellar dust, along with the remnants of countless meteors of all sizes. Elements of high atomic weight are rare or unknown, on Luna ... so much so, that theories have been advanced that Luna didn't even originate among the dense planets of the inner Solar System, but drifted away from one of the outer planets or even from another nearby star-system. Native iron rich in nickel is common, as are native brass (unknown as a natural alloy, on Earth), quartz, spinels, and less-exciting minerals of low atomic weight. In the interest of parallelism, I have chosen to let Matera's geology resemble Luna's in regards to mineralogy ... even though Matera's origin is even more exotic than Luna's hypothetical one!

Neither Luna nor Matera have a magnetic field, making compasses useless. Orientation by stars is also virtually useless, as the near-vertical North/South axis of either moon means the stars are skewed from where they would be visible from the two moons' respective planets; Polaris, for instance, is NOT directly above the North Pole, on Luna. Combined with the extreme curvature of the horizon and the lack of prominent landmarks, explorers face a very real risk of getting lost -- a risk too often ignored, in Hollow World adventures -- and one that could easily be the death of a careless scout, who ventures too far from his or her vessel in areas where moondust is too sparse to hold a clear footprint.

Matera: how it's different

"Golden dome's grandeur,
Oh captain, only I have known;
Ever will I tell thee...?"*

[* - amateur haiku composed by Lady Abovombe six months into her captivity on Myoshima... before Prince Haldemar's continued absence made her want to "tell him" a few things far less poetic]

While Matera resembles Luna to casual inspection through a telescope, it departs from its Earth-bound twin in three important respects: heights of visible external features; composition of its dark-coloured maria or "Seas"; and the appearance of its long-unglimpsed "dark side" (a misnomer, since the far side of both Luna and Matera are illuminated during the new moon).

When astronomers on Earth first endeavoured to map Luna's surface, they assumed that the stark shadows cast by upland features indicated great mountains, deep valleys, and cavernous rifts in the landscape. They were sadly mistaken; while some lunar features IRL appear very tall through a telescope, this is an illusion generated by the extreme reflectivity of porous moonrock. On actual inspection by probes and later by human astronauts, Luna's "towering mountains" turned out to be the gentlest of hills, and the "deep basins" of lunar craters are seldom more than a few thousand feet ... this, in craters dozens of miles across.

Matera, on the other hand, is a fantasy setting, and for Mystara's satellite, those fanciful maps are correct! Altitudes for exterior features of Matera -- which correspond to Luna's exactly, right down to the bright rays surrounding Tycho and other prominent craters -- are increased by a factor of 10, from their counterparts on Luna. Hills of 500 feet grow to nearly a mile high; crevices Neil Armstrong might have hopped down into unhurt, now gape open as treacherous chasms in the rocky ground; ridges of rock that proved mere ripples IRL offer meaningful obstacles for overland travellers. This is why Luftkapitan Kauser could plant Vanya's banner on the peak of a mountaintop rather than a hump on the ground, and why DMs who opt to set adventures on the outer Matera will have something besides flat, uninteresting terrain to describe.

Another feature that differs from Luna -- though in this case, the IRL early moon-geographers are just as wrong -- is the series of lunar maria or "Seas" which cover large regions of the Nearside (these make up face of the Man in the Moon). On Luna, maria are upwellings of dark-coloured magma which cooled into igneous rock-flats, back when both moon and Earth began cooling off after the creation of the Solar System. On Matera, most of these features are something quite different: gargantuan plains of weathered, crystalline rock which, by all appearances, cannot be broken through by any mundane or magical force known to mortals, and resists even Disintegrate spells. (Too bad Herr Kaupf couldn't try those!) Their open surfaces have been minutely scratched by aeons of tiny meteorite-impacts, but chipping a piece loose or digging into these expanses of seemingly-indestructible bedrock is beyond the capacity of anyone but the Immortals; only they, or the patient erosion of time, can wear down these deserts of dark glass. One other "sea" -- Mare Orientale, just beyond the Farward rim of Oceanus Procellarum and the Cordillera Mountains -- is an immense impact crater that provides the only permanent access-point for the Hollow Moon. A few of the smallest Materan maria (Undarum, Spumans, Marginis and Smythii) really ARE inert magma-flats, like their counterparts on Luna.

Quirks of altitude and composition aside, none of the geography on Matera's Nearside should be particularly unfamiliar to players, or even to their PCs; they see them every time they look at the moon, after all! Matera's Farside, however, is another story. While the Nearside's maria, craters, and other physical features correspond precisely to those of Luna, the seldom-seen side of Matera which faces away from the planet in no way resembles the drab, featureless far side of our IRL moon. In fact -- as Lady Abovombe first observed, shortly before composing her poem -- fully 82% of the Farside's land area consists of the same open, crystalline plains which comprise the maria of Nearside. Floodlit by the intense ambient sunlight striking its airless surface, this vast dome of translucent crystal reflects back higher proportions of the red, orange, and yellow components of the spectrum -- glowing, by "day", with a rich golden colour, in a manner not distinguishable in Nearside maria (their colours are "washed out" by white light reflected from non-crystalline rocks and moondust) -- even as it allows greens, blues, and shorter wavelengths to pass through its dense, unbreakable barrier. The unique optical properties of the Farside can be plainly seen by observers in orbit around Matera or from the farther reaches of space; and the bright edges of Farside's "golden dome" are also visible from Patera, when that diminutive moon's skewed circumpolar orbit takes it farthest above or below the plane of the ecliptic.