The definitive technology of the 22nd century is space travel, made possible by the atomic blast, a “safe” nuclear engine. These engines can be built in a variety of configurations, but most spaceship designs are built to take off and land with accelerations of 2g or more, then operate at the safest and most fuel-efficient power setting (usually 0.01g to 0.03g) for the long interplanetary haul.
While this may sound too low to be of much use, even low acceleration builds up impressive speed given enough time. For example, at conjunction, the closest approach of Earth and Mars, the passage to Mars rarely takes more than three weeks (ignoring time for takeoff and landing etc.), even in the slowest of ships:
|0.050g||9.0||The Red Peri?|
The engines of auxiliary rockets and some other specialised engines (such as the under-jets fitted to exploration ships to allow landing on unprepared fields) are built to operate at much higher power ratings for extended periods, since they are almost always used to overcome gravity. Like main engines running at high thrust, they consume much more fuel than would be practical for an extended interplanetary flight, and run a greatly increased risk of failure.
To over-simplify considerably, an engine running on full thrust consumes two to four times as much fuel for any given velocity change as an engine running on its “cruise” settings, and is perhaps five to ten times more likely to malfunction. As designs are refined “cruise” acceleration is slowly rising, as is the reliability of engines at full thrust, but it is likely that even the fastest of ships will have to throttle down, with travel time measured in weeks to months, for many years to come.
The Asteroid Belt adds an extra complication to flights to the outer system, since it often forces ships to make detours or emergency course changes, reducing fuel reserves considerably. At high speeds there is a risk of using so much fuel that it will be impossible to decelerate at your destination, or of extending flights to such an extent that supplies will be exhausted before you can return.
The generally accepted safety limit for a round trip without resupplying is about six months. Since Titan is marginally habitable, with a cold but breathable atmosphere and good supplies of fuel and water, it is a common staging point for trips to the outer system. This isn’t always convenient – for example, a flight to Neptune from Earth would theoretically take 109 days at 0.02g at conjunction, only slightly longer at opposition, all other things being equal; but that takes the round trip time to 218 days, exceeding the safety limit by more than a month. By contrast a flight from Earth to Saturn takes 59 days; the flight to Neptune adds 91 days at conjunction, but begins with a full supply load so that the round trip doesn’t exceed the safety margin.
Life aboard ship is best described as boring, with the low acceleration adding an extra complication to life. It isn’t enough to simulate Earth-like conditions, and is easily confused with free fall, but it’s still strong enough to cause occasional accidents. Objects left in mid-air slowly accelerate aft, and although nobody is known to have been killed as a result, at least one crewman has broken an arm after falling asleep at the forward end of a large hold. While it would be convenient to design ships so that the “acceleration down” is always towards the deck, that’s really only possible with ships that will always land stern-first, the largest liners and freighters.
Exploratory ships and craft that routinely land on ventral underjets are built with the decks running along the length of the ship; it isn’t entirely convenient in flight, but maximizes the utility of the ship on the ground.
In flight spacefarers wear magnetic shoes (boots with spacesuits); with training they learn to instinctively keep one foot anchored at all times, and brace themselves to compensate for the barely-perceptible tug of acceleration, but everyday activities such as washing and showering, cooking, eating and drinking are fraught with complications. There is also a long-term medical risk; prolonged flight at low acceleration can lead to muscle loss and deterioration of bones. Daily exercise and a regime of calcium-fixing tablets are a necessity, and on the largest ships the medical officer has the duty of ensuring that everyone remains fit.
The essential crew positions for any spacecraft are pilot, navigator, and engineer, though in practice the pilot and navigator roles are often combined, especially on long flights where supplies are at a premium. This can cause problems since in an emergency (such as a problem with the atomic blast) a ship may be simultaneously off course and difficult to control.
Piloting requires skill, training, and natural aptitude. In deep space there are automatic instruments to control attitude etc., but even there frequent adjustment is necessary. Takeoffs can be tricky, especially in poor weather or visibility. And landings can be a nightmare, the ultimate test of “seat of the pants” flying. The largest liners and freighters are over a thousand feet long, landing tail-first and vulnerable to every cross-wind and in the final approach dropping into a cloud of flame and smoke that makes it impossible to see the ground and blocks most instruments. Accidents are rare, but can destroy a ship in an instant.
Ventral underjets allow smaller ships to land on their sides, giving the pilot a much better view of the ground, more like a conventional aircraft. The down-side is that they are usually built this way to land on rough fields and unprepared ground. This can sometimes result in unpleasant surprises; for example, apparently firm ground might suddenly turn out to be swamp after it has been thawed by the underjets. If fuel and circumstances permit a good pilot will take things slowly and possibly circle round to check the condition of the landing ground before cutting power.
If there is no Captain in overall charge, when a ship has landed or is in port the pilot usually takes overall responsibility for the safety and security of the ship, deals with officials, handles business transactions, and so forth.
Training obviously focuses on piloting itself, but also includes basic navigation and engineering, sufficient for an emergency, radio operation, etc. It may also include business skills and (in the case of passenger ships) basic etiquette and other ‘people skills.’
The Navigator’s job should be obvious. In deep space position checks should be made several times a day. This involves identifying and taking bearings on several stars and planets, comparison with the current ephemeris, then a lengthy calculation using a slide rule and navigation tables. Instruments commonly used include telescopes with vernier angle measurement on all three axes, spectroscopes to view the spectum of stars, and possibly a bolometer to measure their exact energy levels (this is more useful in the outer solar system, where it’s often difficult to take a fix on more than one or two planets). In the inner system navigation is aided by automatic radio beacons on the major moons and asteroids, but ranges are limited, a few hundred thousand miles at best.
Between flights the navigator must ensure that all navigational materials are up to date, recalibrate instruments, and generally ensure that the tools of his trade are ready. The navigator also ensures that any cargo taken aboard is stowed to keep the mass of the ship properly centred around the line of thrust of its engines.
The profession requires training in astronomy and mathematics, which has led to a major expansion in the astronomy departments of many universities and a boom in theoretical and observational astronomy – with so many students some are bound to take an interest beyond the immediate needs of navigation, and the superb “seeing” in space means that many important discoveries have been made by navigators making observations in their off-duty hours.
Spaceship engineers must be Jacks of all trades, equally at home repairing an atomic blast, a radio transmitter, an air purifier, a meteorite puncture or a dripping shower. In fact most time is probably devoted to keeping the atomic blast running efficiently, to keeping it from failing altogether at full power, and to routine maintenance of life support equipment, with real emergencies a comparative rarity.
Training courses include nuclear physics, electrical and mechanical engineering, plumbing, chemistry, and much more; for example, on exploratory ships the engineer is often also the armourer, and must master gunsmith skills.
Duties don’t end when the ship lands; the engineer is usually busy until it takes off again. Some parts of the atomic blast can only be serviced or replaced when it is shut down, and many servicing jobs are much easier under gravity or in an atmosphere. If fuel, water or air are taken aboard they must be checked for contamination and properly stored.
Next will be the Martians, once I've written more on the "secondary" species and done a couple more pictures.