Friday, November 30, 2007

Hal Clement's "Mission of Gravity" (novel): Imagining a weird world

Quote from the novel titled Mission of Gravity by Hal ClementSomeone described this book as the hardest of hard science fiction - one of the defining stories of the genre. And I will agree, once you make allowances for shortcuts needed to aid story telling.

Very good in my book, but it's not single sitting material. And if you are not from a technical background, you might actually get bored. This is a story to be appreciated for attention to technical detail, rather than any artistic aspects.

I found the ending rather lame.

Mesklin solar system.

Story is set on a weird alien planet named Mesklin.

Humans are visiting it. It has local intelligent beings referred to as Mesklinites.

"Belne" is the primary sun Mesklin rotates about; "greater sun" to locals. Mesklin rotation is in an elliptic orbit about Belne, but we don't have orbital parameters or size of Belne. If the planetary rotation axis is inclined relative the plane of its orbit about Belne, I seem to have missed it.

There is also a secondary sun, "Esstes". From the surface of Mesklin, it appears "brighter than the full moon of Earth". We do not know much else about it - its size, orbital parameters, etc.

Mesklin also has more than one moons. "Toorey" is the "inner moon". Human expedition is camping here, except for occasional visit down or for one member of team, Charles, living near equator of Mesklin through first 40% of the story.

If there is information about other moons, or for orbital parameters or size of Toorey, I must have missed it.

Mesklin planet.

This giant rocky planet is rotating so fast it's shape as seen from space is considerably different from a sphere.

Size of planet is given in many different ways to aid comprehension:
  1. "a polar diameter of less than twenty thousand miles compared to an equatorial one of some forty-eight thousand". That would be a little over 1,50,000 miles equatorial perimeter.
  2. "Thirty-odd thousand miles as the crow flies" from equator to a pole. Corresponding value for earth is 10,000 km (about 6200 miles).
  3. "A ray of light could travel around Mesklin's rim [equator] in ... four fifths of a second".
  4. "proportions of the Bowl on the Bree - Barlennan's equivalent of a terrestrial globe - were approximately right. It was six inches across and one and a quarter deep". "Bowl on the Bree" is the locals' equivalent of a half-globe - cut across equator, & to scale at a gross level.
  5. "a strip of planet a thousand miles wide and something over a hundred and fifty thousand long". "a thousand miles wide" is something I could not figure out.
Whatever it is, it's big. Earth's diameter is less than 13,000 km (about 8000 miles).

This size implies extremely high surface gravity. 3g at equator; about 700g at poles (g = earth gravity). If you weigh 50 kilos on earth, you will be 150 kilos at Mesklin equator, & an unbelievable 35,000 kilos (39 tons - that's may be 7 or 8 adult elephants) at its poles! Different gravity at different latitudes plays a key role in the plot.

This extreme gravity makes physical human landing anywhere away from equator impossible, & very hard at equator.

Mesklin rotates on its axis in about 18 minutes, 80 times faster than earth ((24*60)/80 = 18). And 11 earth years equal two & a quarter years of Mesklin.

This also is a very cold world. During summer near a pole, "The temperature probably goes up nearly to the boiling point of methane - around minus one forty-five at your surface pressure." I don't recall the unit of temperature was ever mentioned. Since the text normally uses miles & yards, I assume the temperature is in fahrenheits rather then centigrades. -145 degree fahrenheit = -98 degree centigrade.

It has vast seas & rivers of liquid methane, with considerable amounts of ammonia & hydrogen as impurities. Methane plays the same role as water on earth; hydrogen plays the same role as oxygen on earth (locals breath hydrogen). Atmosphere contains a lot of hydrogen. I recall at least one reference to "ammonia-tainted methane snow".

Atmospheric pressure at sea level is 8 times that of earth.

At a given location, sea level vastly varies across seasons - by as much as several hundred feet: "Here at the Rim [equator], where shore lines are so steep, it doesn't make much difference; but up where weight is decent the shore line may move anywhere from two hundred to two thousand miles between spring and fall." "Our cities ... are usually on the sea coast in spring and anywhere from two hundred miles to two thousand inland by fall."

There was some explanation for the major sea level change across seasons, but I didn't quite catch it. This makes making land maps extremely difficult - another peculiarity made use of in the plot.

"Rim" is the native's word for equatorial region. Because of peculiar vistas created by local air refractions, his people believe the world to be bowl-shaped. Poles are near "bottom" - where he comes from; equator is the rim - where world ends. "I ... don't see how anyone could get much closer [to equator]. It seems to me that if we went much farther out to sea we'd lose every last bit of our weight and go flying off into nowhere."

The explanation for why the locals from polar regions see peculiar bowl shape: "You get more extensive mirages sometimes even on Earth, but they're all based on the same thing - a lens or prism of colder or hotter air refracts the light. It's the same here, except the gravity is responsible; even hydrogen decreases rapidly in density as you go up from Mesklin's surface. The low temperature helps, of course."

I didn't quite catch the reasoning behind "we are warmest in winter when we can't see the sun for the longest time." Something to do with condensing methane giving off heat, or something, as the planet is moving towards its farthest point from sun in orbit. This is the observation near one of the poles.

Mesklinites, the intelligent local beings.

Because of high gravity, local life (including plants) tends to be ground hugging, except near equator. And there are no birds.

Mesklinites are multi-legged creatures with "caterpillar like body". At one place, I recall a reference to simultaneous use of 6 legs; they might have more. Sailors from a pole that play a major role in the story are "fifteen inches long and two in diameter", though their equatorial brethren can grow to 3 times their size: "Five feet in length they stretched ... with body breadth and thickness to match". And the equatorial ones can rear "the front third of their long bodies high into the air", something polar folks can apparently not do.

These small friendly sailors weigh "2.25 pounds at equator, 550 pounds" at their native place (550/2.25 = 244!). Parts of the story are based on implications of this on natives' psychology.

Their legs apparently also act as arms with "pincer" like appendages that let them do fine manipulation of environment, & are also useful when they want to get violent.

Extreme fear of heights is normal; "a fall of six inches was usually fatally destructive even to the incredibly tough Mesklinite organism" at poles!

Mesklinites are at roughly the level of technology development of Europeans a few hundred years ago. They have some great sailors that go to far off places, though they tend to stick near coast. Simple gliders have been made by other communities. There is no hint if there exists a community of locals that actually understand the geography of their planet in detail.

For the most part, Mesklinites behave like humans - I suppose to aid story telling, because it's very glaring in a story that otherwise pays extreme attention to detail.

Natives refer to humans as "Flyers". Because they can fly, & it's such a magical art on a high gravity world.

The "Bree".

Bree is the name of sea going vessel of the sailors the humans have befriended. It will play a major part in the story.

It's a raft like structure - actually a collection of smaller rafts strung together. Wind powered via sails - "there are masts on twenty or thirty of the rafts". "about forty feet long and a third as wide, and is one of their biggest oceangoing ships. Scarcely any of it is more than three inches above the water".

We are also given some idea of the size of sailing masts of this ship: "ten-inch twig that was one of the Bree's main booms".

Story summary.

Humans landed a specially built vessel costing "two billion dollars" at one of the poles. It came fitted with special instrumentation to measure some unspecified things relating to gravity.

Vessel apparently made successful measurements, but has failed to lift off. For a while, it can stay in touch with controllers above in space via radio, but cannot communicate the data it has gathered. So humans know its physical location with considerable accuracy, but have no way of recovering the data. That is why they are seeking local help.

Charles Lackland, a human member of the mission, will make contact with an adventuresome native sailer, Barlennan, near equator. He will enlist sailer's support to travel halfway through this really big world, & recover the instrumentation - with what help the humans can give in the form of information.

Barlennan will be given several "vision sets" - satellite phones with camera, but with dimensions of a modern cellphone & practically unlimited battery life. This is how he will stay in touch with humans. Multiple instruments will also come in handy to compute the location of search parties relative lost rocket near the end of the story.

Much of the story is of Barlennan & company's adventurous voyage through his world - hunting local animals, meeting other communities that are sometimes very hostile, etc. Many of these people contacts are similar to many adventure stories you might have read. Difference is in detail dictated by high gravity, & gravity gradient as you move across latitudes.

Through out the story, I was confused about which pole was referred to. South pole is where human craft landed. So Barlennan must be from near north pole (he is very far from home, in uncharted waters). But I recall a couple of references to his place as also on south pole! Or may be I was not paying attention!

A few gravity aspects from among the many illustrated.

  1. Hollow sea going vessels like our normal ships or canoes cannot operate at high latitudes. Pressure at same depth under sea rises with gravity, crushing the deep parts of such vessels. Story uses a canoe that is usable at equator, begins giving trouble at 60g, & becomes utterly unusable at 190g.
  2. Jumping, throwing things like spears or even flying is possible at equator, but unthinkable at poles. On throw a ball & catch - even if weight were not an issue: "There isn't time. If something is let go - thrown or not - it hits the ground before anything can be done about it."

Noticeable short cuts taken for the sake of story telling.

  1. How did the humans reach Mesklin?
  2. Human visitors speak English, & Mesklinites speak to them in this language! And the locals have learned the language at a speed that I wish I could learn when I was younger (it's my third language)! Aliens are also comfortable talking in mile & yard - something I still cannot do easily (I am from metric country).
  3. Natives' behavior is way too human-like to seriously call them aliens.

Major actors.

  1. Charles Lackland: Human contact with the natives.
  2. Barlennan aka Barl: Captain of the native ship humans have enlisted.
  3. Dondragmer aka Don: Barlennan's first officer, & a very smart thinker.
  4. Merkoos: Barlennan's second officer.
  5. Karondrasee: Bree's cook.
  6. Dr Rosten: In charge of human mission. He is stationed on Toorey.

Fact sheet.

"Mission of Gravity", novel, review
First published: As a 4 part serial in Astounding Science Fiction, April/May/June/July 1953.
Rating: A
Series: "Mission of Gravity" (A), "Close to Critical" (A), "Star Light" (A).
Related: Stories of Hal Clement.


girotix said...

Very good explanation. I remember I enjoyed this book when I was fiftheen years old (this is... mmm... twenty five years ago!!).

Thank you for your review. Perhaps I would repeat and enjoy now the Clement's book.

Anonymous said...

Great review. Like you some of the things were uncertain to me as well. Clement is a bit dry in style at times. The book was not as quick a read you would think. Still a interesting story and very well researched.