Friday, November 9, 2012

Review of Homer Hickam’s book: Crater

During my adolescent years, some of the most fascinating books I read were what were then referred to as the “Heinlein Juveniles”.  These were imaginative “space operas” written by Robert Heinlein with such a solid underpinning of real science to them that the young reader would not only get excited about the possibilities of space exploration, but also pick up some of the fascinating science associated with space flight.  They inspired many of my generation to dream of adventures in space while contemplating the interesting science behind it, and also led many of us to pursue careers in science and engineering. 

Nowadays, novels for that age group are known as “Young Adult” fiction.   It has been my hope to find some modern day novels that might inspire the current generation of youth, then recommend any worthy books to parents and teachers.  Specifically I am looking for books with a sound scientific basis that will also excite young people similar to the way the above mentioned Heinlein books did for people of my generation.  Indeed, I have encountered some really good recent science fiction yarns for young people.  James Patterson’s Maximum Ride series comes to mind, as well as Harry Turtledove’s Crosstime Traffic series.  Other books of more mass appeal such as the Hunger Games series are really good and thought provoking science fiction stories, but no books of the grand space opera variety were evident in my searches.

Enter Homer Hickam’s new young adult novel Crater.  Many of you may recognize Homer as the author of the inspirational autobiographical book The Rocket Boys.  The Rocket Boys was the basis for a popular movie in the late 1990s known as October Sky.  In fact, I would recommend both the book and the movie to readers and movie watchers of all ages.  I will never forget the reaction of my mother to seeing a trailer for October Sky on TV.  That promotional footage showed boys launching their homemade rockets and also contained a heated argument about space between the young protagonist and his father.  Such scenes were witnessed in real life by my mother decades before, prompting her to ask me, “Did someone make a movie about your life?”

But back to Crater.  I won’t write enough detail to spoil reading it for anyone.  The story takes place on the future colonized Moon.  Our heroes are an orphaned teenage boy named Crater Trueblood and Maria, who is the slightly younger granddaughter of a powerful owner of a helium 3 mine.  They undertake a long journey on an important mission that involves travelling across the inhospitable lunar surface.  Crater must avoid enslavement by outcast genetically modified misfits, while also escaping death at the hands of very malevolent and grotesque cyborg commandoes who are intent on making sure our young heroes never reach their destination.  I will only tell you this much more: two of my favorite characters are Gillie who is kind of an intelligent iPhone made of living organic goo, and Pegasus – a real live horse who Crater finds in the lunar wastelands.  For those who find the latter character as incredulous as I did at first, Hickam presents Pegasus’ existence in at least a passably realistic and scientifically plausible way.   

I thoroughly enjoyed the book.  It contained high adventure peppered with cool scientific principles, such as: solving the world’s energy problems by mining the Moon’s massive quantities of helium 3 and shipping it back to Earth for use in nonpolluting fusion reactors that produce enormous amounts of electricity from just small amounts of helium 3.  There are also spacecraft which follow “cycler” orbits that minimize the fuel and expense required for deep space flight.  I could list more.

OK now, I get to the uncomfortable part.  Though most of the science in the book is very sound, I found some scientific inaccuracies that prompted me to contact Homer to see if he would object to my publishing a review that would include their mention.   After reading my short list of scientific flaws, he graciously informed me that he had no problem with my covering them.  So here goes …
1)   On pages 29-30, the beginnings of Earth rise from the vicinity of the Apennine Valley is mentioned.  As is typical of locations on the near side of the Moon, the Earth would never rise nor set, but essentially maintain a relatively fixed position in the sky that would only vary a little from stationary (this wobbling effect is called lunar libration) because of the Moon’s elliptical or oval shaped orbit.  The only times the Apollo astronauts saw Earth rise was when they were in orbit around the moon, since it was their orbital motion that caused the Moon to rise and set.  There is one thin strip on the Moon where rising and setting of Earth could occur and that is at the extreme edges of the lunar hemisphere visible from Earth where libration would occasionally cause the Earth to rise a little above the horizon and then shortly thereafter set where it rose.
2)   On page 245-246, the heroes travel up to an altitude of 60 miles on a space elevator extending up from the lunar surface and once that height had been achieved, they were in a condition of microgravity.  The only way microgravity conditions can exist at that altitude above the lunar surface would be for objects travelling at the orbital speed for that altitude.  The part of the elevator at 60 miles high would not be travelling at orbital speed.  In fact the weight of objects in the elevator at that altitude would be (by my calculations) about 93% of what it would be on the lunar surface.
3)   The most viable place for a shuttle to rendezvous with a space elevator is at the lunar equivalent of geosynchronous orbit (that is, selenosynchronous orbit) and that is also the place where microgravity conditions exist.  Of course, the elevator’s counterweight would be even farther out.  The shuttle craft (that was to take our heroes to the cycler ship Elon Musk) would not have been docking at 60 miles altitude because the part of the elevator at that altitude would be far below orbital speed.  Going at the elevator’s low lateral speed at that altitude, the ship would drop like the proverbial rock.  The only way a shuttle could pick people up from an elevator at that altitude would be for it to do a rocket powered landing on a platform attached to the elevator, then take off under rocket power.
4)   On page 289, it is stated when Crater extracts water from the lunar soil, “water … filled the resulting hole.  Before the pool could evaporate, Crater used a hand pump to fill a collapsible container …”.  Liquefied water exposed to high vacuum evaporates vigorously fast (almost explosively).   It would dissipate as fast as it formed.   As a teenager I experimentally exposed a cup of water to vacuum and saw this happen first hand.

I might also add that there are a few references to centrifugal force that should properly be termed centrifugal effect.  This is the apparent pseudo-force that seems to pull outward on a massive object moving in a circle that is held in its path by an inward pulling true centripetal force.  Instead of being a true force, centrifugal effect is merely a side effect of the object trying to travel in a straight line which the centripetal force does not permit.  For instance, if someone in a circular rotating space station “drops” a ball, it appears to fall to the floor in a slightly curved path and seems to be pulled down toward the floor by a force causing the ball to flee in an opposite direction from the center of the station.  That appearance of being pulled away from a center is the very source of the term centrifugal, from the Latin words “centrum” for center and “fugit” meaning “to flee” or “run away from”, as opposed to centripetal with “petal” derived from ”petus” meaning “seeking”; thus, a centripetal force tries to pull things toward the center of a circle.   

However, someone standing outside the space station (assuming the station has transparent walls) will see that the apparently falling ball is really traveling in a straight line path that is tangent to the circular surface of the space station (due to the ball’s inertia because of Newton’s first law of motion) until the ball hits the floor; whereupon, it takes on the circular motion of the floor of the space station but appears to be sitting still to someone standing inside of the rotating space station.  The ball will appear to have weight seemingly because it is being pressed against the floor by a centrifugal force, but in reality it is just the ball’s inertia trying to move it in a straight line in a direction that is tangent to the rotating motion of the station.  Thus, it is actually being held in place by the true centripetal force imparted by the structural strength of the space station’s “floor”.  In short, there is no such thing as centrifugal force; instead, what we call centrifugal force is just an observed effect caused by the centripetal force.

I heartily recommend Crater, regardless of those few objections. Judging from its subtitle, "a helium 3 novel", it appears that Crater may possibly be a first novel in the "helium 3" series of books and thus could offer readers something to anticipate as far as future adventures for Crater and Maria.  Regardless, Crater was a fun tale in which the main characters seemed real enough to care about with a plot of high interest to keep my attention until the end.  Give it to a young person in your life who likes a good read.


  1. Interesting "fact checks".
    1. I think I took the Earth rising as being due to their travel, but I didn't look up the locations to see if that made sense.
    2. I might point out that Ben Bova makes the same mistake in "Mercury" during a flash back tothe building of an elevator. The heros get off at LEO and are weightless. Also, when terrorists sever the connection of the cable to the platform at GSO, he has the cable fall around the Earth, crushing everthing in its path. Since it is traveling at the same speed as the surface, I think it would just fall straight down, wouldn't it?

    1. As I have already mentioned, I discussed these problems with Homer himself. Your assumptions are not correct.
      1) On page 26, that Earth rise scenario was not due to their travels. That was before Crater began his travels for his mission.
      2) I have not read "Mercury", but if the heroes get off of the elevator at the Mercury equivalent of geosynchronous orbit, they would indeed be weightless. Had Crater gotten off the lunar elevator at selenosynchronous orbit he would have been weightless and the shuttle could indeed have docked there. Homer told me he thought of having Crater ride all the way to selenosynchronous orbit, but said the ride up the elevator that far would have taken too long for the hero to accomplish his mission on time.