Enceladus or Bust

kw: book reviews, science fiction, space fiction, space aliens

Just to set the right expectations, the space aliens in Threshold by Eric Flint and Ryk E. Spoor are long extinct, having apparently blown each other up in an interplanetary civil war about the time the dinosaurs went extinct. The book is the sequel to Boundary by the same two authors, and I presume much more is explained there.

In keeping with much modern adventure fiction, there is the obligatory setup of intrigue and power politics, and the expected psychopathic villain, this time a ship's chief of security. While he is the only true villain onstage, there are hints of bigger, more evil villains behind the scenes, even funding his hidden agenda. An unusual feature of this novel is the death of about 90% of the characters, including half of the named cast. It also ends in a cliff-hanger that ensures at least another book (or five) in the series.

Setting all that aside, there are two good ideas of how to power a spaceship, and some really blue-sky notions about nanotechnology and "smart dust" type sensors. The "mass beam" propulsion system is one way to reduce the amount of onboard fuel a ship needs. A railgun type of propulsor sends lots of dust into space ahead of a spacecraft, timed to intercept its expected trajectory. The first half of that trajectory, its velocity will be much greater than the ship, so as it is captured (by a means not explained), it transfers momentum to the ship. It also can act as reaction mass by being heated in an onboard nuclear reactor and spit out the back again. In the latter part of the trip, the dust is traveling slower than the spacecraft, which is now pointed the other way, so the ship is slowed by catching the dust, and slowed again by using it for reaction mass. If the "mass" is smart enough, it can be guided by a ship-mounted laser to more accurately center on the expected trajectory, which reduces waste. I shudder at a technology that can produce thousands or millions of tons of material composed of germ-sized robots.

The nebula drive is more subtle. It uses a huge magnetic field to entrain dust, either dumb or smart, which is pushed upon by both the solar wind and by sunlight. The magnetic field is supported by room-temperature superconducting ribs extending from the ship's midsection (the superconducting technology is courtesy of the extinct aliens). In areas away from a planet's magnetosphere, the field's effective diameter can be a thousand kilometers. That can catch a lot of sunlight. Tacking maneuvers are needed in the second half of a trip, to use the sunlight and solar wind to slow the spacecraft.

Then there is the smart dust itself. The technical protagonist, named A.J., deploys two kinds of the stuff. One kind, called Locusts, is larger, the size of a pencil eraser or so, and a flotilla of these can carry out complex jobs and those requiring strength. Faerie Dust, on the other hand, is almost invisible but can interact with electronic systems. Both communicate with A.J. by cooperatively generating a radio signal and acting as an extended antenna.

The capabilities of such micro- and nanosensors (and -effectors) are gradually unfolded as the novel proceeds. At one point, a dose of Faerie Dust is made into an antipersonnel weapon by A.J. to immobilize a few bad guys. Somehow they get inside their bodies and interrupt key nerve signals. At another, A.J. is able to gain partial control of another ship's propulsion and communications systems. The guy must have an IQ of 700. In real life, just writing the virus code one wants the dust to carry could take months, and the software that allows the dust motes to insert code fragments into a computer system could take decades to perfect. He does the first job in a matter of hours, and the other over a week or two.

The novel is fast-paced, which necessitates leaving out a lot: its time frame is just about ten years. Even with the super-fast drives described above, it takes a few months to get a ship to Mars or Ceres, and even longer to get to "outer system" space, Jupiter and beyond.

The rub in interplanetary voyaging is the time required. The ballistic orbit between Earth and Mars, the Hohmann orbit, takes about a year, each way. The NASA Mars project is considering a somewhat more costly alternative that cuts the one-way time to about eight months. To get three men to the Moon and back required a little over a week, and the supplies, mainly water and oxygen, were a huge inventory item. Multiply that to between seventy and ninety weeks for a Mars mission. The more water, oxygen and food you take along, the more fuel you need to push it all into the transfer orbit, slow the craft down at Mars, get back into Mars orbit, and return to Earth.

But put all that aside and enjoy the ride. It is likely at some point that people will go to Mars and even farther. Some of the ideas in Threshold may indeed be used to help them get there.