by Mark Anson
The Mesa is also equipped with a variety of systems for implementing the various deflection methods for asteroids. Although the most dramatic method (nuclear shaped charges) are described in the story, the Mesa can equally well push against smaller objects to change their velocity, or ablate material from the surface to impart a small thrust.
The Mesa also carries large stores of cryogenic propellants for its manoeuvring engines, located at the end of the ship, near the reactor. These engines can be started and restarted rapidly for the sudden changes in velocity needed during rendezvous manoeuvres.
The Ulysses
The Ulysses is the second of the Columbus-class vessels commissioned exclusively for scientific and exploration work. Its principal targets for detailed investigation and survey are the icy moons of the Outer Solar System, principally those of Saturn.
The Columbus-class vessels are based on an earlier version of the deep space tugs, and utilise a solid core nuclear reactor with the reactor fuel contained in metal-clad fuel rods. Although this delivers a lower specific impulse than the later gas core designs, the reactor benefits from a simpler construction. Like the Mesa, the Ulysses also carries stores of cryogenic propellants for its manoeuvring engines.
As described in the story, the entire crew module can detach from the rest of the tug in an emergency, such as a main engine failure. In this case, the conventional rocket engines on the crew module can utilise the cryogenic propellants to get the crew back home, or to a place of safety.
As befits a vessel intended for exploration, the Ulysses also carries a landing craft. This small vehicle is capable of independent flight and can undertake landing and takeoff from low-gravity bodies. It carries sufficient fuel and stores to allow a small team to spend up to several days exploring the surface.
Human hibernation
To date, there has been no success in inducing hibernation in a large mammal that does not naturally hibernate. Most experiments have taken place in mice, and there are very substantial challenges in scaling these up to an animal the size of a human.
The most feasible approach would appear to be a combination of both drug- and temperature-induced hibernation, but there remain enormous challenges in controlling the changes required to induce hibernation and recover successfully from it. To reduce body tissues to low temperatures quickly enough to avoid serious tissue damage, the blood must be at least partially replaced with a chilled saline or Ringer solution, a very hazardous procedure in a living organism. Revival would involve reintroducing warmed, stored blood, and restarting the heart’s normal rhythm, which would have been kept beating by electrical stimulation during hibernation.A complex regime of drugs to induce, maintain, and recover from stasis would also be required.
If stasis could be achieved for long periods (many months to a year), the benefits for long-distance interplanetary travel would be immense. Tonnes of food, oxygen and other consumables would be saved, and the loss of muscle and bone mass caused by reduced gravity would be mitigated by slowing down metabolic processes.
The risks of stasis, however, are severe. The human body, which is thought to have evolved in a warm climate, is simply not developed to hibernate. The body fights any attempt to reduce its temperature, and will damage itself through the immune system on revival, potentially causing serious tissue damage.
Human hibernation is firmly in the realms of science fiction, and likely to remain so for the foreseeable future.
Orbital mechanics
The positions of Earth, Mars, Venus, Psyche and other major bodies are described as they would appear in 2148–2149. The orbital transfer trajectories, journey times and spacecraft manoeuvres described in the story are consistent with the technologies described for the space vehicles and their performance data as shown in the drawings.
There are, however, some places where accuracy has been sacrificed intentionally, for dramatic effect.
The descending node
The astrological symbol for the descending node, or south node, is shown on the book cover and title page, and represents the point in a body’s orbit where it passes down through a reference plane, in most cases the plane of Earth’s orbit around the Sun. The threatening asteroid 2010 TG4 is intercepted in the descending node of its orbit, and this incident also marks the downward turn in Clare’s career. In medieval astrology, the symbol was also called the dragon’s tail (Latin: cauda draconis) and referred to the descending node of the Moon’s orbit.
MANNED DEEP SPACE VESSELS
IN USAC INVENTORY, 2141
Deep Space Tug (STN) – Boston-, San Diego- and Omaha-class space tugs.
Deep Space Explorer (DXN) – Columbus, Magellan- and Cook-class science exploration vessels based on the Chicago-, Philadelphia- and Arlington-class designs.
Deep Space Interceptor (DIN) – Seattle-, Philadelphia- and Arlington-class dedicated asteroid movers based on the Boston-, San Diego- and Omaha-class space tug designs, with increased propellant and thrust capability.
Venusian Carrier (VCN) – Atwood-class airborne carriers, designed to operate in the lower atmosphere of Venus.
GLOSSARY
Aphelion – in astronomy, furthest distance of an orbiting body from the Sun.
Cryogenic – super-cold; generally, any temperature below about –100 °C or 173 K. Commonly applied to gases that need to be held at these very low temperatures to remain liquid.
Descending node – see Background Notes.
Ecliptic – the plane of Earth’s orbit around the Sun.
Gamma ray – highly penetrating electromagnetic radiation with wavelength less than 10 picometres, usually arising from disturbances within atomic nuclei.
Gee (g) – an acceleration equal to that exerted by gravity at Earth’s surface, approximately 9.8 m/s2.
Hill sphere – an imaginary sphere around a body within which the body can exert its influence in the face of perturbations from a larger one. The Moon is within Earth’s Hill Sphere and can therefore exist as a satellite of Earth rather than the Sun.
LO2 – common abbreviation for liquid oxygen.
Megaton – amount of TNT explosive (in millions of tonnes) required to equal the energy released in a nuclear explosion.
Orbital inclination – for a planet, the inclination of its orbital plane round the Sun relative to that of Earth’s. All the planets orbit within a few degrees of this plane.
Perihelion – closest approach of an orbiting body to the Sun.
Propane – gaseous hydrocarbon of the alkane family, chemical formula C3H8. Can be liquefied at cryogenic temperatures.
Scram – emergency shutdown of a nuclear reactor.
Sidestick – evolution of the more traditional control yoke, for controlling an aircraft in pitch and roll. A sidestick is controlled by small wrist and arm movements, and can be operated even under high-g conditions.
X-ray – form of electromagnetic radiation, usually emitted by electrons, with wavelength between 0.01 to 10 nanometres. Widely used to image the inside of objects.
Yield (of nuclear weapon) – the amount of energy released when a particular nuclear weapon is detonated, usually expressed as a TNT equivalent, see Megaton.
Zulu – Zulu Time, a standard aviation term for UTC, broadly equivalent to Greenwich Mean Time (GMT).
SELECT BIBLIOGRAPHY AND FURTHER READING
Beatty, J. Kelly (ed.), Carolyn Petersen (ed.) and Andrew Chaikin (ed.) The New Solar System. 4th edn. Cambridge University Press, 1999.
Belton, Michael J.S. (ed.) et al, Mitigation of Hazardous Comets and Asteroids. Cambridge University Press, 2004.
Birch, P. ‘Terraforming Mars Quickly’. Journal of the British Interplanetary Society 45 (1992): 331-340.
Clarke, Arthur C. Rendezvous with Rama. Gollancz, 1975.
Clarke, Arthur C. The Hammer of God. Gollancz, 1993.
Fogg, M.J. ‘A Synergic Approach to Terraforming Mars’. Journal of the British Interplanetary Society 45 (1992): 315-329.
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sp; Greeley, Ronald, and Raymond Batson. The Compact NASA Atlas of the Solar System. Cambridge University Press, 2001.
Lewis, John S. Mining the Sky: Untold Riches from the Asteroids, Comets, and Planets. Basic Books, 1997.
McKay, C., J. Kasting, and O. Toon. ‘Making Mars Habitable’. Nature 352 (1991): 489-496.
Sobel, Dava. The Planets. Fourth Estate, 2005.
Verschuur, Gerrit L. Impact! The threat of comets and asteroids. Oxford University Press, 1996.
MOST MASSIVE ASTEROIDS
In the table above, ‘size’ shows the largest dimension – asteroids are usually irregular bodies. The ‘percentage mass’ is shown as the proportion of the total mass of all known asteroids. ‘Carbonaceous’ or C-group asteroids fall into several sub-types, but all tend to be dark, carbon-rich material, sometimes high in volatile content. ‘Silicate’ or S-type asteroids are composed mainly of rock.
One year later …
SOME SECRETS ARE BEST LEFT UNDISTURBED …
Mercury – closest planet to the Sun. In the permanent darkness of Chao Meng-fu crater lie vast fields of ice that that have never seen the Sun, and the ruins of Erebus Mine, abandoned and forgotten after a devastating explosion that claimed the lives of 257 people. After an eight-year legal battle, the relatives of the victims have finally succeeded in forcing the Space Accidents Investigation Board to reopen its investigation. The mission team is led by Clare Foster, a pilot in the U.S. Astronautics Corps, who has taken on the mission in the hope of rebuilding her career after a near-miss incident.
But powerful forces are determined that what lies hidden in the mine will never be uncovered, and have taken steps to ensure that the mission team will never return …