On screen! . . . For obvious reasons, this assignment you will need to learn via remote. This interstellar craft should also be familiar to you. The ISV Venture Star is one of a twelve vehicle fleet which provides commercial space transportation between Earth and Alpha Centauri.
As with the other ships of the “Capital Star” class, it was designed to carry a large payload of cargo and passengers to the worlds of the Alpha Centauri star system, especially the rich world of Pandora.
The ships of this class are not exploration ships, they are commercial freighters. The ship's mission is to be part of an endlessly looping supply chain which enables the exploitation of the indigenous resources of Pandora. The ISV Venture Star, and the other ships of its class, represent the highest technological achievement in human history. Only the great need for unobtanium and the energy which it allows human civilization to produce could justify the cost of creating these vessels.
In fact, the unobtanium itself enabled the creation of this class of ISV’s. It is used in the superconducting magnet arrays which contain and direct the energy of the matter-antimatter annihilation which propels the ship. Without unobtanium, interstellar commerce on this scale would not be possible. Unobtanium is not only the key to Earth’s energy needs in the 22nd century, but it is the enabler of interstellar travel and the establishment of a truly spacefaring civilization.
The Venture Star is the ninth ship of its class brought into service, and has made one round trip to the Alpha Centauri System. It is currently outbound on its second voyage, due to arrive there in 2154. Talk of “wormholes” and “warp drives” captured the imagination of twentieth-century sci-fi fans, but no such methods have come to fruition. For now, engineers must rely upon techniques that exploit our current understanding of physics. Visionaries set their sights on the potential for matter-antimatter reactions.
The enormous energy released in the annihilation of matter and antimatter is the only known means of creating the kind of propulsion needed for interstellar travel. The first interstellar ship was over four kilometers long, because of the massive refrigeration system required to maintain the conventional low-temperature superconducting magnets that produced the containment field for the matter-antimatter reaction.
It was not until the discovery of the high-temperature superconductor unobtanium on Pandora that interstellar travel and commerce became commercially viable. The Capital Star Class ISV was developed using this technology and is one-quarter the size of that first ship, and many times more efficient. Power Source: Hybrid deuterium fusion / matter-antimatter annihilation.
Propulsion: Two hybrid fusion/matter-antimatter engines. One photon sail. One fusion PME (Planetary Maneuvering Engine.) Beamed photon power from Earth for outward acceleration phase; ship’s hybrid fusion / matter-antimatter power for deceleration phase on approach to Pandora. Sequence reversed for return to Earth.
Engines: Two, arranged symmetrically in a tractor configuration. They are angled outward a few degrees off the ship’s longitudinal axis so their exhaust plumes bypass the ship’s structure. This results in a slight cosine loss to thrust efficiency, and the body of the ship must be shielded from the plume’s thermal radiation, but the mass-savings advantage of a tensile structure outweigh these disadvantages.
Since a very long truss is needed to separate the habitable section of the ship from the engines which produce large amounts of radiation, such a structure would be prohibitively massive if it were a conventional space-frame truss designed for compressive loading. But the carbon-nanotube composite tensile-truss creates the necessary stand-off distance at one tenth the mass. Essentially it is a tow cable with enough torsional rigidity to allow the ship to maneuver, including the pitch-over maneuver which must be performed to turn 180 degrees for the deceleration burn when inbound to Pandora.
A matter-antimatter reaction causes the total conversion of matter into energy, as per Einstein’s famous formula of E = mc2. The antimatter (in this case anti-hydrogen) is contained by a magnetic field in a near-perfect vacuum in which it circulates as a high density cloud of atoms cooled to near-absolute-zero temperature. When antimatter and matter (normal hydrogen) are brought together, they mutually annihilate and produce an enormous amount of energy, which must be directed by an ultra-powerful magnetic field to form the exhaust plume.
These photons of energy, although massless, possess momentum, and their ejection provides the thrust to accelerate the ship. Additional thrust is obtained by injecting hydrogen atoms into the plasma before it leaves the engines. The exhaust flare is an incandescent plasma a million times brighter than a welding arc, and over thirty kilometers long. The plume is considered to be one of the most spectacular man-made sights in history.
Structure: The ship's primary structure (which could only exist in zero gravity) consists of the two side-by-side engines attached to a tensile-truss of carbon-nanotube composite. This connects the propulsion section to the payload section, which includes habitation modules for crew, the cryovaults for passengers, amnio tanks for the avatars, and the cargo section. Starting from the forward end:
1. Engines, propellant tanks, and radiators. The propellant tanks are spheres insulated for zero boil-off of the cryogenic hydrogen propellant. The radiators dissipate the heat of the engine section. After a deccel or accel burn phase, the radiators will glow red hot for 2 weeks.
2. The tensile-truss that transfers the thrust of the two engines to the rest of the ship. Although thin, it is rigid enough to prevent the payload section from fishtailing caused by buildup of resonant frequency vibrations during acceleration and deceleration. The section of the truss adjacent to the antimatter engine nozzles is protected by a thermal shield of nearly perfect reflecting materials, to guard against the intense heat radiated from the exhaust plumes.
3. Cargo containers, arranged in four ranks of four modules each. The 16 modules are in turn composed of 6 cargo pods. Depending on the cargo bay configuration of the shuttle, it can hold the contents of two pods and 100 passengers in jump seats, or up to the contents of six pods and no passengers. A mobile transporter running on tracks can position a large robotic arm for transfer of the cargo modules to and from the trans-atmospheric shuttles.
4. Two Valkyrie TAV’s (trans-atmospheric vehicles) docked to access tunnels. The tunnels connect to a pressurized tunnel that runs through the truss, and connects to the habitation section.
5. The habitation section consists of three large modules containing the cryovaults and amnio tanks. Inside each module is an open frame structure of advanced composites, with non-load bearing walls made of foam composite. There is almost no metal used in the structure. This is to prevent galactic cosmic radiation from striking metal and producing secondary radiation particles. There are a number of airlocks for the crew, and portals for repair bots that look like high-tech mechanical crabs.
6. Immediately behind these three modules are the two on-duty crew modules, located at the opposite ends of a transverse truss. A pressurized tunnel runs through the truss, connecting the two units. During cruise mode, these modules can be rotated to create an artificial gravity for the on-duty crew. During accel and deccel phases, the modules fold along the longitudinal axis of the ship.
In this configuration, the gravity is created by the acceleration of the ship (so all floors and walls are still correctly oriented to the gravity vector). The modules also provide centrifugal artificial gravity during the ISV’s one year loiter on orbit at Pandora.
7. At the far end of the structure is the mirror shield, which protects the ship from the intense light of the beamed-power laser from Earth. This mirror is only a few molecules thick, but reflects light efficiently enough to prevent incineration of the habitable section of the starship. When acceleration is completed, the ship is rotated 180 degrees so that the mirror shield faces forward. Now the shield performs another role, acting as a multi-layer interstellar debris shield. Although intense magnetic fields are used to deflect stray gas molecules, the occasional dust grain requires a physical barrier.
The shield is in multiple layers, spaced one hundred meters apart. Impact of a debris grain (traveling at a relative speed of 0.7C) with the first layer of the shield causes vaporization into a plasma. The spray of plasma particles strikes the second layer, and the impacts cause spalling from the back of the second layer. These particles are stopped by the third layer. A fourth layer acts as a backup in the unlikely event that something gets past the third layer.
Once cruise speed is reached, this shield is detached and moved by small thrusters thousands of miles in front of the ship, to improve survivability if a larger particle of debris is encountered. The largest component of the ship is not located on the primary structure. It is the “sail” which receives the beam of photons and extracts the momentum to accelerate or decelerate the ship. It is a shallow bowl 16 kilometers in diameter and stabilized by rotation. The material of the sail is incredibly thin, being only a few dozen molecules thick in most places.
Its basic structure is a fabric woven from carbon nanotube thread, and coated with a refractory ceramic that fills in the interstices. The working side of the sail is further coated with a vacuum-deposited multi-layer diachronic reflector, which is 99.99999% efficient. What little heating of the sail that occurs is dissipated by radiation from its back side.
Carbon nanotube cables connect it to the main body of the ship, and these cables also have a diachronic coating which reflects 99.99999% of the beam energy that strikes them, and prevents the cables from instantly vaporizing. When not in use, the sail is folded along molecular hinge lines, and occupies a surprisingly small volume. It is stored in the cargo area when not in use, along with the spools of connecting cables. Rigging and removal of the sail is done autonomously by the service bots, but can be done manually in an emergency by awakening the other two crew teams.
Life Support: All consumables are recycled to the maximum extent possible. Oxygen is reclaimed from carbon dioxide by fractional distillation of the ship’s atmosphere, which also removes all gaseous contaminants. Additionally, this process removes water vapor and purifies it for drinking. Steam distillation is used to reclaim more drinking water from urine and solid body waste. The dehydrated and sterilized remains are used as fertilizer in the hydroponic gardens where fresh fruits and vegetable are grown to supplement the crew’s diet of freeze-dried and irradiated food.
An auxiliary atmospheric system provides a much larger amount of oxygen, and carbon dioxide removal, for the short periods when the vessel is in orbit around Earth or Pandora, and the passengers and full crew are not in cryopreservation. Since it is not practical to maintain this condition for the duration of the voyage, in the event of a failure of the cryonics system the passengers would be euthanized before awakening, so that the crew can continue the mission and deliver the cargo. (The extra crew teams’ cryopreservation system is separate, and extra-redundant.)
Cryonics Systems: The on-board cryonics systems are to put passengers into suspended animation for the duration of the journey to save resources, the cryopreservation compartments are to freeze their occupants and maintain them at sub-zero temperatures.
A passenger is strapped to their compartment with sensors to measure temperature, heart rate, brain activity etc. which are vital in the reanimation process, they are then given an anesthetic and put to sleep, the heart is put into cardiac arrest and liquid nitrogen floods the compartment and freezes the body, the remaining liquid nitrogen is drained and the body will remain in cryopreservation for the remainder of the journey provided the body remains in sub-zero temperatures.
The problem of irreparable cell damage caused by the formation of intra-cellular ice crystals that stymied 20th Century life-extension attempts was solved by using low doses of microwave radiation to jostle the water molecules as the temperature drops, and completely prevents the formation of any ice crystals.
Before the ISV reaches its destination, the body is warmed to room temperature and the heart is restarted with an electric pulse, however the anesthetic should still be active after the heart is restarted so instead of having a violent awakening from a long journey, the anesthetic slowly wears off and the passenger simply wakes up. After the passenger wakes up the sensor detects brain activity and automatically opens the cryopreservation chamber. The reanimation process is closely monitored by every able-body crew member as it is still a really risky process with many problems.
Crew: 25
The ship’s functioning is largely automated, using triply-redundant, radiation-hardened computers, but emergency manual control is provided for all functions. The minimal crew is cross-trained in all specialties. There are five crew teams of five each, who serve for 14-month tours, and are in suspended animation for the balance of the voyage.
This seeming waste of mass was necessitated by the experience of mid- 21st Century space missions when crew members proved psychologically unstable after a year in close confinement. The main function of the human crew is to monitor the power and propulsion systems and also passengers in cryopreservation. Humans have the ability to notice anomalies too subtle for the automated monitors, in spite of these systems’ tremendous sophistication.
Passengers: 100
The passengers are placed in cryopreservation so that they do not require any air, water, food or any other resources for the duration of the journey. Typical outbound passengers are replacements for RDA personnel, troopers, and avatar operators. Inbound passengers are limited to those who have finished their tour of duty. Unfortunately, the cost of shipping back personnel precludes returning individuals still under contract who have medical problems that cannot be treated on Pandora, so they are euthanized there. The only exception to this policy is for high-level RDA executives.
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