The Rocky Realm
Nonfiction – by Peter Jekel
Asteroids have us in their sight. Neil deGrasse Tyson
Johannes Kepler, German astronomer, mathematician and astrologer is perhaps best known for his discovery of the laws of planetary motion—the first two laws were published in 1609 in Astronomia Nova and the third in his 1619 Harmonices Mundi—which formed a foundation for the work of Isaac Newton and his discovery of the universality of gravity in 1687. Kepler’s work was highly dependent on the astronomical observations of Danish astronomer, Tycho Brahe, who was well-known for the meticulousness of his observations. Before he made his landmark discovery, though, Kepler noted, based on what he was seeing in Brahe’s observational catalogue, in his 1596 Mysterium Cosmographicum, that there was a “gap” in-between the orbits of Mars and Jupiter that he could not explain. Something had to fill in the void, he thought, but nothing seemed to be there.
There was further speculation about the “gap” between Mars and Jupiter by Genevan philosopher and naturalist, Charles Bonnet. (Bonnet had earlier described what has become known as Charles Bonnet syndrome which is a hallucinatory disease where people perceive things that are not really there.) In 1766, he translated German astronomer Johann Titius’ Contemplation de la Nature. He saw a footnote that showed that the layout of the planets followed a numerical sequence beginning with 0, 3, 6, 12, 24, 48 and so on. Those numbers were then each increased by four and divided by ten; the result was a good approximation of the orbits of the known planets at the time but there was still that nagging “gap,” that Kepler had mused about. German astronomer, Johann Bode further refined Titius’ footnote and actually used it to calculate the orbit of Uranus; German-born English astronomer, William Herschel is credited with discovering the planet however. Bode’s reformulation became known as the Titius-Bode Law. All was working well except, again, for that gap between Mars and Jupiter. There was nothing to fill a void where a planet should exist.
Then in 1801, the first object in this mysterious void of space was discovered by Italian priest, astronomer and mathematician, Giuseppe Piazzi. Piazzi called that world Ceres and classed it as a planet. The “gap” was now filled and vindicated the Titius-Bode Law at least until such time as the law fell apart with the discovery of Neptune in 1846. Only in the 1850s when more rocky objects were found to exist in this region of space which became known as the Asteroid Belt, that Piazzi’s world became just another rock and was demoted to an asteroid. It stayed with this lowly status for many years. In 2006, it was promoted again, not quite a planet, but a dwarf planet, like Pluto. Ceres is one of the only objects in the Asteroid Belt that is known to have a spherical shape due to its gravity whereas other objects are mostly irregularly shaped rocky objects. In fact, it possesses a quarter of the mass of the entire asteroid belt.
Asteroids are not only irregular in shape but their surfaces are scarred by years of collisions causing them to be pitted and cratered. They move around the Sun in elliptical orbits, rotating on an axis; some would likely describe it more as a tumbling than a rotation, due to their shapes. Many asteroids, up to 150, actually are accompanied by a moon of their own with some even having two.
Though the most threatening asteroids to the Earth are ones that cross our planet’s orbital path, the asteroids of the Main Belt between Mars and Jupiter are not innocent bystanders either. They periodically stray in their orbits due to the gravitational influence of giant Jupiter and to a lesser extent Mars, knocking the pieces of rock elsewhere in the Solar System, sometimes on a collision course with Earth some of which have directed the course of life on Earth.
There are three broad classifications of asteroids based on their composition. One is the C-type asteroid, the “C” an abbreviation for carbonaceous. Darker in appearance than other classes of asteroids due to their makeup of predominantly clay and silicate rocky material, they are likely the oldest objects in our Solar System that have changed little since their formation. Seventy-five percent of all asteroids fit this class of objects. S-type asteroids are stony asteroids made up of iron and magnesium-silicates and nickel-iron metal; around eight percent of asteroids are in this classification. Lastly there are the M-type asteroids, which are similar to the S-type. However, instead of silicates, they are made up almost completely by metals such as iron-nickel. They are likely to have formed closer to the Sun since they show evidence of an exposure to a high temperature sometime in the past, so hot in fact that they partly melted. This resulted in the heavier iron to sink to the core. Seventeen percent of all asteroids fit this category.
Soon after the discovery of asteroids, science fiction writers were not far behind in taking advantage of the new setting for their tales. Naturally one of the first out of the gate was science fiction pioneer, Jules Verne. In his 1877 Off on a Comet, he describes a tour of the Solar System with a ride on a comet. The comet, in its travels, sweeps by a recently discovered asteroid Nerina. Nerina was not an actual asteroid at the time of the story, but sixty years later, an asteroid was discovered and named, Nerina, not after the Verne tale but in honor of the plant genus Nerine, made up of flowering plants in South Africa. Verne passed his writing baton onto his son, Michel, and together they wrote, The Chase of the Golden Meteor in 1908. The story is about a rivalry between two amateur astronomers, both of whom take credit for the discovery of an asteroid. The need for fame becomes secondary and somewhat problematic when the asteroid is on track to crash into Greenland.
The first object in the Asteroid Belt discovered, Ceres, has been visited by NASA’s Dawn spacecraft. The craft was launched in 2007 and propelled by ion engines before entering orbit about the dwarf planet in 2015. The mission ended on Halloween in 2018. In addition to the plethora of data sent back, there were also a number of photographs. Some of the most interesting photographs are those that show what appears to be a reddish briny ammonia solution in the Occator Crater, which indicates the likelihood of ammonia salt water below.
The dwarf planet, by Asteroid Belt standards, has an impressive radius of 476 kilometers. It inhabits the zone where the Titius-Bode Law predicted a planet would exist, precisely at 2.8 AU from the Sun. It takes 4.6 years to orbit the Sun but its day is a mere nine hours long. That is just part of what is interesting about its rotation. Since its axis of rotation is almost perpendicular with respect to the orbital plane, it actually has no seasons unlike other planets and dwarf planets. It is the axial tilt of the Earth at 23.5 degrees that gives us the variability that we enjoy in our seasons.
Ceres is structured very similarly to that of the inner planets rather than like its asteroid partners. Like the planets it has a layered interior comprised of a surface which shows evidence of many small and relatively new craters, but few large or older craters, a liquid mantle (likely water/ammonia ice) and a solid core. Measurements taken by Dawn indicate that there is likely a layer of liquid water that survived under the layer of ice. It is estimated that the dwarf planet actually has more water than the Earth, being twenty-five percent water. The presence of a liquid layer leaves open the door to the possibility of life on Ceres.
Why the surface is relatively devoid of older and larger craters could be due to the icy layer beneath the surface. The lower density of the ice is known to smooth out surface features over time. Another more interesting possibility for the crater “erasure” and one that is gaining traction for other worlds that have recently been explored in our Solar System, the presence of ice volcanoes, which would further indicate a liquid layer beneath the surface.
In keeping with its dwarf planet status, Ceres even has a thin atmosphere, mainly consisting of water vapour, the likely source being possible ice volcanoes or ice on the surface sublimating in the “heat” of the distant Sun-the temperature on Ceres ranges between -73 degrees Celsius during the balmy daytime and down to -143 degrees Celsius at night.
Ceres certainly was popular with science fiction writers even well before its status change to a dwarf planet. In the tales it usually has the status of a lonely outpost in space, serving as a base of operations in the Asteroid Belt. Isaac Asimov wrote a series of juvenile novels early in his writing career, the Lucky Starr series. One, Lucky Starr and the Pirates of the Asteroids, is similar to nautical tales of pirates of the seas; in this case our hero encounters pirates who raid the Asteroid Belt. Ceres, in the story, plays a prominent role as not only a base for Lucky to operate from, but also as a target of the pirates. In Bertram Chandler’s, Raiders of the Solar Frontier, Ceres is described as a prison world. In Jerry Pournelle’s Exiles to Glory, Ceres serves as the setting for a mystery in which super-heavy metals from the asteroids are stolen. Thomas Wren, in The Doomsday Effect, describes a black hole that is slowly destroying the Earth; Ceres is used to capture it to save the planet. The Killing Star by Charles Pelligrino and George Zebrowski, is about an alien attack on the Earth. The few human survivors hide out in the interior of Ceres. Instead of a sanctuary, Bob Shaw, in his The Ceres Solution, Ceres is used by extraterrestrials to destroy Earth’s Moon. However, in spite of the destruction, their intentions are good as by destroying the Moon, they will destroy forces that have apparently repressed human cultural development. Interesting idea, since the Moon has been deemed an essential ingredient to the success of intelligent life developing on the Earth.
Most of the objects that reside in the Asteroid Belt range in size from less than a kilometer in diameter to even lesser sizes. It is estimated that there are between one and two million objects in this region of space. They are the shattered remnants of the formation of the Solar System, bodies which never grew large enough to become a planet.
There are some larger bodies in the Belt however. Vesta, discovered in 1807, holds the title of being the largest asteroid in the Solar System. It actually contains nine percent of the mass of the entire asteroid belt, so that together Ceres and Vesta have over a third of the Belt’s mass. The asteroid is spherical in shape and almost made it as a dwarf planet but didn’t quite make the cut. Like the inner planets and its Asteroid Belt partner Ceres, it, too, is layered with a surface, mantle and core. NASA’s Dawn spacecraft visited Vesta orbiting it in 2011, before its rendezvous with Ceres.
Vesta has some interesting geological features of its own, one being the fact that it probably has the biggest range of brightness of any object in our Solar System with extremely bright objects, likely rocks that made up the original asteroid body of Vesta, and darker areas which are likely the accumulation of dust from collisions with the asteroid—Vesta appears to have been the target in a shooting gallery. Studies show that over a period of 3.5 billion years, over three-hundred objects between one and ten kilometers in diameter have hit Vesta, creating a blanket of material that ranges between one to two meters in thickness. Other evidence of Vesta’s bombardment are some large craters. One crater on Vesta is around five-hundred kilometers in diameter, almost 95 percent of the diameter of the world itself and another one, is around four-hundred kilometers in diameter. Adding to its geological curiosities, scientists have discovered at Vesta’s equator, a system of troughs that encircle the asteroid. The largest of these troughs is called Divalia Fossa, a feature bigger than our Grand Canyon.
Though Vesta is the largest asteroid out there, it really has not been as big a hit with science fiction writers as Ceres but there are a few. One tale that takes place on Vesta is actually science fiction legend Isaac Asimov’s first published work. In his 1938 “Marooned Off Vesta,” passengers of a disabled spaceship are stranded in orbit about the asteroid. He also wrote Lucky Starr and the Rings of Saturn, which sets Vesta as the site to host an interstellar peace conference. Only Superhuman, by Christopher Bennett, takes place not directly on Vesta, but in stations in orbit about the asteroid. Like other large asteroids in the Belt, Larry Niven’s Known Space series does have a media centre for the Asteroid Belt on Vesta, called the Vesta Beam.
Asteroids in the Main Belt have also been visited by our spacecraft. The first such mission was NASA’s Galileo spacecraft which on its way to the Jovian system flew past Gaspara in 1991 and Ida in 1993 both asteroids in the Main Belt. Gaspara is an inner asteroid of the Main Belt and is curious in that though it has a number of craters it also has a number of large flat areas. Scientists are not sure if these features are the result of larger impacts or pieces breaking off of the main body. Ida, on the other hand, is an irregularly shaped object and also holds the title of being the first object in the Belt to be found to actually possess a small moon.
There was a theory that the rocky remains in the Asteroid Belt are the remnants of an exploded planet, sometimes going by the name of Phaeton. Ideas on how this explosion happened are collectively known as the disruption theory. One idea is that the planet ventured too close to the gravity well of Jupiter where it was torn apart by tidal forces. Another suggested possibility is that the original world was shattered by some unknown geological catastrophe. Another theory is that the planet was demolished by a strike from another planet-sized body. Then there is the theory that it could have something to do with the gravitational effects of Nemesis, a theoretical companion star to the Earth, that was thought to be responsible for the regularity of mass-extinctions on the Earth. The partner star to the Sun, Nemesis, has been now largely dismissed by scientists.
Today astronomers feel that the likely origin of the Asteroid Belt is the accretion model, that the asteroids of the Main Belt are remnants that never came together to form a planet, likely in part prevented by the tidal forces created by the gravity of Jupiter.However, the idea of a fifth planet certainly gained a following in the science fiction community. Seola, written in 1878, was written by American author, Ann Eliza Smith. The novel mentions a world that lay between Mars and Jupiter; its destruction was the cause of the Biblical flood. “In Time Wants a Skeleton,” published in 1941 by American science fiction author Ross Rocklynne, humans travel back in time to see the fate of Phaeton; the Earth-like planet was destroyed by a collision with another planet.
A number of science fiction authors looked at the fifth planet as having been home to an advanced prehistoric alien race of the Solar System (there are similarities to the stories of the lost continent of Atlantis tales), who destroy their world through nuclear war. Juvenile novel, Return to Mars, by an English World War I pilot, W. E. Johns, tells the tale of the fifth planet called Kraka being destroyed by its inhabitants through an accidental nuclear accident. In The Destruction of Faena, by Russian science fiction writer, Alexander Kazantsev, the fifth planet was destroyed by a nuclear war amongst the inhabitants of the world many thousands of years ago, well before humans even left their caves. Some survivors of the horrific holocaust escaped to Earth where they mixed in with native humans. The human race, according to the tale, is a mixture of human and Faetan genes. In a similar vein, James Hogan wrote the Giants series which began with Inherit the Stars. The story begins with a scene where astronauts discover an alien skeleton inside of a spacesuit on the Moon; the skeletal body is estimated to be over fifty thousand years old. As the story evolves, the reader discovers that there was a fifth planet called Minerva that exploded during a nuclear war fifty thousand years ago. The remains of this incredibly destructive war ended up being today’s Asteroid Belt. A larger fragment, however, was thrown to the outer Solar System to become the dwarf planet Pluto. Robert Heinlein in one of his juvenile novels, Space Cadet, our hero, upon graduation from the Space Patrol Academy, discovers that the Asteroid Belt is the result of an exploded planet, called Lucifer. He also discovers that the original inhabitants are responsible for the world’s destruction.
Self-destruction by the inhabitants served as one explanation for a fifth planet, but other writers looked to Martians as being responsible for the planet’s demise. The proximity of the Asteroid Belt was proving threatening to Martians as depicted in some works by a couple of science fiction masters. In Fallen Star, by James Blish, the fifth planet, Nferetet, is destroyed by Martians who saw the planet as a threat. Robert Heinlein in his classic, Stranger in a Strange Land, the fifth planet is unnamed, but is described as having been destroyed by Martians.
Frederic Brown, in his short story “Letter to a Phoenix,” takes a completely different spin on the destroyers of the fifth planet. They are not the original inhabitants or Martians but one of several earlier human civilizations on Earth.
The destruction of the fifth planet has also made it into the adventures of legendary detective Sherlock Holmes. In Arthur Conan Doyle’s Valley of Fear, a treatise by Holmes’ arch-nemesis, Professor Moriarty, entitled, The Dynamics of an Asteroid, is described but its contents never disclosed. In “The Ultimate Crime,” by Isaac Asimov, he hypothesizes that Professor Moriarty’s The Dynamics of an Asteroid, is actually a complex mathematical dissertation to explain the destruction of the fifth planet; Moriarty had wanted to use that data to perform the same with the Earth.
Frederic Brown, in his Rogue in Space, looked at the reason for the demise of the fifth planet from an entirely different angle. In this tale, he envisions an intelligent living asteroid that goes about collecting all of the asteroids in the belt and forms a planet with itself at the core. In the tale, the Asteroid Belt exists as we see it today whereas a completed fifth planet will be a part of our future.
In addition to the Main Belt asteroids, there are also a class of asteroids known as trojans. Trojans are those asteroids that share orbits with larger planets. Jupiter has the most significant population of trojans, but there are also ones following Venus, Mars, Uranus and Neptune as well. Interestingly enough, with the other gas giants and even most of the inner planets having them, giant Saturn does not have any. Earth has one trojan that was first discovered in 2010, 2010TK7. Another Earth trojan was discovered on December 12, 2020.
Max Wolf, an astronomer at the University of Heidelberg discovered the first trojan asteroid, one of Jupiter’s, on February 22, 1906. In fact, it could be said that he was an all-star champion of asteroid discovery, having discovered 248 asteroids in his lifetime (June 21, 1863-October 3, 1932). His success was due to his use of astrophotography. With his stereo comparator, he was able to concurrently look at the same regions of space photographed at different times, thus allowing him to see the “moving” stars in the background.
In Stephen Baxter’s Manifold: Time, he describes intelligent squid who work on a quasi-satellite asteroid of Earth, Cruithne. Quasi-satellites are similar to trojans in that they share an orbit with a planet around the Sun but have very erratic orbits that differentiates them from trojans; there are over twenty such objects known to science co-orbiting with the Earth. As a quasi-satellite, Cruithne co-orbits the Sun with the Earth, in a quasi-satellite fashion-it stays close to the parent planet for many orbital cycles, but not as a true satellite like our Moon. It does move with the Earth in its journey around the Sun, thus taking the same length of time of one year. It, however, also follows a horseshoe-shaped orbit relative to the Earth, that takes it inside the orbit of Mercury and out past Mars in a horseshoe-shaped orbit around the Earth every 770 years. Other planets and even some asteroids, have quasi-satellites of their own.
Of most interest to us perhaps are the near-Earth asteroids which have highly eccentric orbits that take them close to the orbit of the Earth. The ones that actually cross the Earth’s orbit are known as Earth- crossers. There is a group of Earth-crossers that are especially concerning, known as Apollo asteroids first discovered by German astronomer, Karl Reinmuth. As of June 2013, over ten thousand near-Earth asteroids have been discovered with 861 of them having a diameter of over one kilometer and 1409 that could one day make life very different here on Earth. The Jet Propulsion Laboratory manages NASA’s Center for Near-Earth Objects Studies which monitors the movements of many space objects including comets and asteroids that veer close to the Earth. They define a Near-Earth Object (NEO) as an asteroid or comet that comes within 1.3 astronomical units (distance of the Earth to the Sun) of the Earth. Arthur C. Clarke’s classic Rendezvous with Rama actually begins when an asteroid destroys northern Italy. The response is the development of the Spaceguard program to watch out for near-Earth asteroids that may impact the Earth. The program results in the discovery of the alien space artifact that has entered our Solar System, Rama.
John Baxter wrote of the Hermes asteroid on a collision course with the Earth and our attempts to deflect it. Hermes is an actual near-Earth asteroid. It is under a kilometer in diameter and part of a binary system on a very eccentric orbit. In fact, in 1937 it passed within twice the distance of the Moon to Earth, really close when looking at objects in our night sky. Arthur C. Clarke’s The Hammer of God is about the fictional asteroid Kali (Kali is the name of the Hindu goddess of time, doomsday and death) hitting the Earth. Jack Williamson’s Terraforming Earth is about an asteroid that wipes out most of life on Earth; however that is not the end of the story. The survivors of the destruction are clones on an automated lunar base. In Stephen Baxter’s Titan, China tries to deflect an asteroid into Earth’s orbit to serve as a weapons base, instead causing it to crash into the planet, destroying life on a massive scale.
There have been a number of missions to the near-Earth asteroids. In 2000 NASA’s Near Earth Asteroid Rendezvous (NEAR) spacecraft, renamed after its launch as NEAR Shoemaker, in honour of the American geologist, Eugene Shoemaker who, along with his wife Caroline and Canadian amateur astronomer, David Levy, discovered Comet Shoemaker-Levy 9, not only became the first spacecraft to orbit an asteroid but in 2001 actually landing on one, the asteroid being Eros. The craft was not designed to be a landing craft however, but still it managed to survive its touchdown and transmitted for around two weeks before succumbing to the extreme cold of its new extraterrestrial home on February 28, 2001.
Eros was the first asteroid to be discovered inside of the orbit of Mars on August 13, 1898. It is a member of the near-Earth asteroids coming as close as 26 million kilometers of the Earth. It displays extreme changes in brightness as it rotates quickly on its axis. It has an elongated shape, sometimes described as peanut-shaped, and relatively small in size. Eros is undifferentiated, unlike Ceres and Vesta, so that it is likely to be made of original Solar System material.
Though somewhat plain when compared with some asteroids, Eros is still a popular destination for science fiction writers, probably in part due to its relatively close proximity to the Earth. Stanislaw Lem’s “Let Us Save the Universe,” found in his satirical The Star Diaries, Eros is described as being heavily vandalized with graffiti. Michael Swanwick in his Vacuum Flowers, describes a number of space stations in orbit about Eros.
Some authors have looked to Eros as being an ideal setting to be manipulated by humans. Harry Harrison in his Captive Universe, describes Eros as being hollowed out to create a generation ship, the setting for the rest of the tale. In Ender’s Game, by Orson Scott Card, Eros is first an outpost of the aliens that Earth is fighting, the Formics. The aliens use Eros to serve as a base for their invasion of Earth, even going so far as to put in an artificial gravity. Eventually the world is captured by humans and becomes the training base for Ender Wiggin, the hero of the Ender series in humanity’s continued fight against the Formics.
In Stephen Baxter’s Evolution, Eros takes on a very different role. In spite of its near-Earth status, it does not pose a threat to the Earth at the present time. However, millions of years in the future after a disturbance in its orbit, the asteroid collides with the Earth, bringing about a mass extinction. For dramatic effect, Baxter describes the shell of the space probe NEAR Shoemaker still standing on the surface of the asteroid just before its impact.
The next major landing on an asteroid happened in 2005 with the Japanese probe, Hayabusa, which entered the orbit of near-Earth asteroid, Itokawa to collect samples. Hayabusa carried a lander (MINERVA) but it failed in its landing attempt. In order to salvage the mission, the main craft Hayabusa was landed on the asteroid instead. Not designed to land, instead it was designed to just touch the surface with its sampler and then move away. However, ground control was able to make it land; it actually was on the asteroid for thirty minutes. On June 3, 2010, it returned to Earth bringing with it a valuable collection of dust from the asteroid that is currently being studied.
In 2014, the Japanese launched Hayabusa 2 which arrived at near-Earth asteroid Ryugu in June 2018. It deployed not only a lander (MINERVA-II) onto the surface but four mini-rovers to survey the asteroid to provide a visual background of where asteroid samples of the asteroid were going to be taken. In February 2019, the lander fired an explosive to create an artificial crater on the world allowing the collection of a sample from beneath the surface. Mission Control decided, with the successful retrieval of samples, to extend the mission to explore more asteroids and even conduct surveys to look for exoplanets beyond our Solar System. Current mission plans extend to 2031 when the probe is to reach another asteroid for study.
NASA also, on October 20, 2020 landed its Osiris Rex spacecraft on the near-Earth asteroid, Bennu. While on the asteroid, the craft took a sample of the asteroid. The sample is around sixty grams of material and is slated for return to Earth in 2023. Bennu is a tiny object that appears to be more of a conglomeration of smaller rocks than a solid rock. During its 1.2 year traverse around the Sun it will make a close approach to Earth every six years.
Icarus is another near-Earth asteroid that has an extremely eccentric orbit and is considered to be potentially hazardous to the Earth. Its orbit is so eccentric, in fact, that it actually swings in closer to the Sun than Mercury and then swings out again out beyond the orbit of Mars. Icarus also holds the record of being the first asteroid to be seen on radar in 1968. It is also a popular destination for science fiction writers. In Arthur C. Clarke’s “Summertime on Icarus,” an astronaut becomes stranded on the world. Kim Stanley Robinson’s The Memory of Whiteness, we find an Icarus that is inhabited by a religious cult that worships its close approaches to the Sun. The asteroid plays a significant role in Gregory Benford’s In the Ocean of the Night, the first part of his Galactic Center series. It follows the placement of a nuclear bomb on the asteroid to alter its course away from the Earth; calculations show that it was likely to strike India. The hero is to place the weapon and then detonate it. Before he does so, he is able to convince NASA that it would be better to place the bomb in a fissure found in the asteroid. Within the fissure are found metal strips with artificial patterns, evidence of extraterrestrial intelligence. This scene puts in motion the Galactic Center series.
Near-Earth asteroid, Didymos is an asteroid with a small moon, Dimorphos, of its own. Its moon is not likely to be from a strike or gravitational capture, but more likely due to the rapid spin of the parent world, which takes only 2.26 hours to complete one of its days; the moon actually formed out of this quick rotation of the object where material was actually ejected. So far, the pair do not really pose a lot of risk to the Earth (unless there is a disturbance in its orbit). The asteroid pair is still of interest to scientists, though. They were chosen by NASA’s Double Asteroid Redirection Test (DART), the space agency’s first mission to test planetary defense against a possible strike by a near-earth asteroid with the Earth. Scientists want to determine how much of an impact would be required to alter the orbit of the orbiting moon; this was accomplished by deliberately crashing the craft into the asteroid. This data will be crucial to determining the force required should a larger object start to make headway to our planet. DART, launched in November 2021, was a success having deflected Dimorphos on September 26, 2022, having successfully deflected the world, even surpassing the original calculations of NASA engineers.
Another group of asteroids are the hybrid centaurs. Centaurs are smaller Solar System bodies that have characteristics of both asteroids and comets that have very unstable orbits as they cross the orbits of one or more of the giant gas planets; only one called Ka-epaoka’awela is known to have a stable orbit but it is retrograde. Some objects that move in the Centaur region of space display very comet-like characteristics in that they even display cometary comas, the hazy covering around the nucleus or core of the comet which gives comets and some centaurs a fuzzy appearance when viewed through a telescope. Two objects, Chiron and Echeclus are classified, in fact, as both asteroids and comets. There are estimated to be between 44,000 and ten million of the Centaur objects greater than one kilometer in diameter. The first Centaur object discovered was Hidalgo in 1977. Far more interesting though is the ringed world, Chariklo which is 260 kilometers in diameter. It is one of five known bodies in the Solar System (the others are the giant gas planets) now known to have a ring system. Its ring system is also quite substantial considering its small size. The ring system of Chariklo is between three to seven kilometers in width. It has now been hypothesized that Ceres may have originated in the outer Solar System as a Centaur. The same possible origin has been hypothesized for Saturn’s moon, Phoebe.
Of all of the objects in our Solar System, it is likely that asteroids will be the first to be exploited by private firms. Within the asteroids, are potential precious metals such as gold, silver and even platinum. Even baser metals, if found in large enough quantities could prove profitable for a private enterprise. As we continue to exploit the materials here on Earth and with increased private activity in outer space, it is only a matter of time where the money required for such a feat will be all worthwhile.
A number of the tales of colonization and exploitation of the Asteroid Belt attempt to create the feel of a “gold rush in space,” with names such as “Belters” and “Rock Rats” to describe locals, being bandied about. Perhaps the oldest tale of asteroid exploitation is found in American astronomer’s Garrett Serviss’ 1898, Edison’s Conquest of Mars. In the story, a fleet of ships on their way to engage in war with Martians stop at an asteroid that is being mined for gold. Tales of the Flying Mountains by Poul Anderson is a collection of short stories about the colonization of the asteroids. Protector by Larry Niven, part of his Known Space series, looks at the psychology of people born and raised on the asteroid colonies, nicknamed Belters. The Venus Belt, by L. Neil Smith is about a social system of total free enterprise on asteroids not unlike the lawlessness of several locations of past gold rushes. Ben Bova’s Asteroid Wars series, describes warfare between corporations to control the wealth of the Belt; “Rock Rats” is a term used to describe miners in the Asteroid Belt. Seetee Ship and Seetee Shock by Jack Williamson, the inner worlds and Jovian moons are dominated by tyrannical governments much like we saw in Europe prior World War II, Communist, Fascist and Corporate “democracy.” The miners on the asteroids referred to as “Rock Rats” are the only humans left independent of the tyrannies. Isaac Asimov in “Catch That Rabbit,” in his I, Robot collection, a mining station on an asteroid acts as a lonely setting for one of his mysteries. In Robert Heinlein’s juvenile novel, The Rolling Stones, the Stone family moves to the Asteroid Belt to take part in an equivalent of a Gold Rush. Their twin teenage boys, who are quite business savvy, pick up supplies and luxury goods on their stopover on Mars to sell to the miners of radioactive ores. In Harold Goodwin’s Rip Foster Rides the Gray Planet, an entrepreneur captures an asteroid made of pure thorium-thorium is a heat-resistant metal used in heat-resistant ceramics among other uses-and steering it into Earth orbit for exploitation. Hard science fiction writer, Geoffrey Landis has some short stories set in the asteroid belt that deal with the mining of asteroids, Outsider’s Chance and Betting on Eureka. In C. J. Cherryh’s Heavy Time, the mining of the Asteroid Belt is actually an essential part of Earth’s economy in the 24th century. “Tinker,” found in Jerry Pournelle’s short story collection, High Justice, describes multinational corporations and their interactions with the miners of the Belt. In a twist, the corporations are actually the “good guys,” not the evil faceless villains often found in stories, and it is the miners that are the “bad guys.” Norman Spinrad, known for a number of political themes disguised in his science fiction, wrote The Men in the Jungle. The Asteroid Belt has been colonized by Afrikaners who greedily guard the mineral wealth of the Belt, creating in effect, another Apartheid. Poul Anderson’s “The Rogue” is a love affair between an entrepreneur of the Asteroid Belt and an officer of a warship from the Social Justice Party. Fred Hoyle’s Element 79 looks at an asteroid made mostly of gold which inflicts a great deal of difficulty for Earth’s economy. In Blue Mars and 2312, Kim Stanley Robinson writes some vivid descriptions, a trademark of his writing, of asteroid colonization.
Asteroids are also seen as weapons by some writers. Larry Niven’s Protector describes an ice asteroid that is diverted by an alien race (who are related to humans) to collide with Mars; water is poison to native Martians. In Niven’s novel, Footfall, written with his frequent writing partner, Jerry Pournelle, aliens who have the appearance of elephants launch an asteroid to crash into the Indian Ocean resulting in the destruction of India, but also having a devastating impact on the countries that surround the ocean. In Robert Heinlein’s Starship Troopers, the alien “bugs” launch an asteroid at Earth which destroys Buenos Aires in Argentina. John Ringo in his Live Free or Die and its sequel Citadel, depicts asteroids that are melted, reformed and act as invincible starships.
Other authors have looked at the possibility of life or past life on the asteroids. In Frederick Pohl’s Gateway, which served as the beginning of his classic Heechee stories, an asteroid with an unusual orbit is explored leading to the discovery of hundreds of small spaceships left by a mysterious alien race; the only problem is that the ships are preprogrammed and no one knows where they will end up or if they will be able to return. Isaac Asimov’s “The Talking Stone” describes silicon-based life found on some asteroids. In Stephen Baxter’s “The Fubar Suit,” asteroid Hektor is the setting for an astronaut who is stranded on the asteroid. The suit is made to recreate the astronaut when her corpse is discovered. Unfortunately the inventors forgot one thing, microbes evolve in the suit, threatening the manufacturer’s guarantee.
Of all of the alien worlds out there waiting for us to explore, the asteroids are a potentially lucrative target which should attract investment for outer space exploration from the private sector. Asteroids are also important for another reason since the near-Earth asteroids probably are a greater threat to us than any other natural disaster. Over one hundred tons of debris hit our atmosphere daily, burning up before it hits the ground. About thirty actually reach the ground. One likely hit the Earth in the Tunguska Region of Russia in 1908 leveling an area over 2150 square kilometers. The object didn’t land but actually exploded above the Earth so that no impact crater was ever found. In 2013, Russia was affected by another exploding asteroid in Chelybinsk in 2013. More than a thousand people were hurt and many windows shattered. The ones that we are really worried about like the one that exterminated the dinosaurs happen on a scale of once every one hundred million years or so, the question of if is not relevant it is a question of when.
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