JumpShip

Description

In the BattleTech universe, JumpShips are the pivotal element of interstellar travel. They facilitate faster-than-light (FTL) movement - "Jumping" from one Jump Point to another, typically in a different star system, covering up to 30 light years in mere seconds. Docking Hardpoints allow JumpShips to carry DropShips along for the Jump, effectively serving as a jump tug.

Jumping with their load of DropShips is about the only task that JumpShips are designed to perform. It is the DropShips that handle all movement of goods and passengers within a star system (including to and from Jump Points), while the large and fragile JumpShip remains at the Jump Point.

Although the term JumpShip technically describes any spaceship that can "jump", it is generally applied only to civilian JumpShips, as opposed to designated military JumpShips (which are usually referred to as WarShips instead). This article adresses the former, vastly more common type; the differences of WarShips are covered in their own article.

History

The Deimos Project was a Terran Alliance project authorized by the Terran Alliance Parliament in 2103 to build the first faster-then-light (FTL) drive.

Part of the Deimos Project, the TAS Pathfinder was the first manned interstellar space craft (JumpShip) that explored the Tau Ceti system.

Design

Designed exclusively to provide FTL jump capacity, JumpShips are essentially comprised of only the elemental components required for Jumping: The delicate Kearny-Fuchida Drive (K-F drive), which alone accounts for around 95% of the ship's mass and dictates the typical needle-like appearance of their fuselage, and the trademark Jump Sail to safely recharge their drive with solar energy. K-F drives cannot be smaller than 2500 tons. The theoretical maximum size for JumpShips is 500,000 tons (civilian) or 2,500,000 tons (WarShips). Most, but not all, have Hardpoints with Kearny-Fuchida Field Conducting (KFFC) Booms that extend the jump field to include docked DropShips. JumpShips are not meant to move away from Jump Points and do not have transit drives like DropShips, only weak maneuvering thrusters to adjust their position. Other than that, they only provide crew quarters and a bridge, and sometimes feature a Grav Deck, hydroponic gardens, modest cargo capacity and/or hangars for Small Craft.

Common JumpShips carry insignificant weaponry at best or are entirely unarmed, and are considered non-combatants. However, the distinction is somewhat blurred in some cases, as some JumpShips do have some level of armour and armament; these are colloquially called "Jolly Rogers". Some JumpShips have command and communication facilities suited for coordinating large military operations, and some even serve as starfighter baseships. The key difference between civilian JumpShips and WarShips is held to be their K-F drive: All ships with a regular K-F drive are considered (civilian) JumpShips, whereas all ships with a compact K-F drive are automatically considered WarShips.

Operations

JumpShip operations are naturally limited, owing to the narrow performance profile of the ships. They do little more than jump. Between jumps they charge their jump drive and wait for DropShips to arrive and dock.

The maximum range for K-F drives is 30 lightyears. Experimental drives exist that may jump longer distances, but none was technically mature enough to be entirely safe to use. Also, misjumps have been known to move ships across hundreds of lightyears in a single jump, and possibly much more.

The destination of a jump can be any jump point within range, even very close. It is a well-known maneuver, for example, to jump from one of a star system's standard jump points to the other.

Jump preparation

In order to safely jump, a JumpShip must operate in zone where gravity levels are below a certain minimum. These zones are generally referred to as "jump points." The typical jump point is found at a minimum distance from the local star known as the "proximity limit," which is where gravity drops below the critical level for the hyperspace field of the Kearny-Fuchida drive to form properly. Except for small zones near outer planets, the entirety of space beyond a proximity limit is a valid jump point - it is quite possible to jump into the depths of interstellar space between two stars. However, habitable planets are exclusively inside proximity limits, so JumpShip operators are usually interested in jumping as close to the planet as possible to minimize DropShip travel time. Thus, they use a "proximity point" that is on the spherical "proximity limit" around the star.

JumpShips rarely use just any proximity point. Rather, navigators usually target points on the proximity limit above and below the poles of the star (as defined by the system's plane of the ecliptic): the "zenith" and "nadir" jump points, also called the "standard" jump points. These jump points minimize the influence of planetary gravity on jump calculations . Indeed, jump calculations made from a zenith or nadir point are usually satisfactory for up to six months before planetary movement necessitates their recalculation.

Those navigational calculations usually only take a few minutes when jumps are performed between standard jump points and are made using the JumpShip's navigational computer. Jumps between standard jump points can be calculated by hand if necessary, though doing so takes hours and increases the chance of a misjump. Jumps to non-standard points, be they other proximity points, deep space points, or "pirate" points, can take hours and are much more likely to cause a misjump .

Other preparations are necessary. Any DropShips accompanying the JumpShip must be docked and properly secured with KFFC Booms. The drive coil must be fully charged.

For safety reasons the JumpShip should also have furled its Jump Sail and confirmed that no other craft are within twenty-seven kilometers. When the jump program is initiated, it becomes impossible to abort the jump process except by the safety systems of the drive itself.

Jump

Within a few minutes after firing up the K-F drive, warning klaxons announce the impending jump and seconds later the K-F field expands around the ship. Warnings usually begin at 10 minutes, then 5 minutes, 1 minute, 30 seconds, and 10 seconds before the jump. Though a jump seems instantaneous, it can take several seconds depending on the distance traveled and the maximum number of DropShips carried. A fully laden Potemkin-class WarShip jumping 30 light-years would require 375 seconds to complete a jump.

The field only correctly encompasses objects within the JumpShip or a DropShip that is properly connected by a K-F Boom, but its effects can be felt up to 27 kilometers distant from the JumpShip. For units not equipped with a K-F Drive, these effects include massive, but potentially survivable, stresses as space is twisted by the forming hyperspace field. However, if another K-F drive is in the forming hyperspace field the jumping ship, the field will be distorted and both ships will suffer catastrophic drive interactions. Contrary to the hopes of some, leaving a K-F drive unpowered or drained of liquid helium coolant will not escape this itneraction effect - it is inherent to the "drive coil," the massive titanium-germanium core of the K-F drive. Even with all other components of the drive destroyed, so long as that core is in fairly large chunks, it is threat. JumpShip salvage typically involves grinding the core to gravel and, if possible, chemically modifying it so the carefully engineered titanium-germanium mix is disrupted .

While a JumpShip may be in motion relative to the origin jump point (a fact used by WarShips from time to time), a JumpShip always arrives stationary with respect to the destination jump point. That is, it matches the motion of the destination jump point . Tacticians must simply accept they cannot pop out of hyperspace with some initial motion relative to the destination jump point.

Passengers typically suffer mild dizziness from jumping. Some even suffer serious nausea for some time after a jump, in a fashion similar to sea-sickness.

Damaged components of the Kearny-Fuchida drive may cause the jump attempt to fail, usually because safety systems abort the jump when the hyperspace field forms improperly. In the case of particularly abrupt aborts, K-F drive damage may result, leaving the ship stranded at its origin.

Misjump

Even if the Jump does not fail, a misjump can occur because of miscalculations, technical problems or spatial anomalies. Navigational errors are the most common cause for a misjump , but poor maintenance (typical during the technological decline of the Succession Wars) or rapid charging are also common sources of misjumps.

It has also been explained that, because of the JumpShip's limited meteoritic shielding, occasionally "something in the doorway could cause an accident" during jumping. However, objects in the hyperspace field generally do not cause misjumps unless the objects have a K-F drive of their own, as noted above. In fact, the incidents of misjumps caused by foreign objects are astronomically rare.

Spatial anomalies are far rarer, but are suspected to have caused the loss of several JumpShips over the millennium of their use.

Inherent mechanics ensure that JumpShips rarely jump deep into the gravity well of a star or planet, except in cases of extremely poor navigation. These usually only occur when a JumpShip is attempting to target a small pirate point inside the proximity limit of a star system and ends some kilometers off-course. During wild misjumps, the reluctance of the hyperspace field to form in gravity levels above the safe limit generally prevents this catastrophic event.

Misjumps, at those misjumps where the jump proceeds rather than being aborted, can deviate from the JumpShip intended destination and emerge off course. Errors are typically in terms of kilometers or astronomical units, but misjumps of light-years have occurred . Sometimes they even end up in a different star system than the one that they intended to jump to, or stranded in deep space. Misjumps have even been known to move ships far beyond the safe 30-lightyear-threshold occasionally. The accidental discovery of Alfirk occurred due to a misjump that carried the ship across several hundred lightyears in a single (mis-)jump. Such long-range misjumps tend to require very unusual astronomical conditions.

Evidently, spatial anomalies are not entirely random. Although it is not known within the BattleTech universe, the novel Far Country describes (from an omniscient perspective) that the human theories about hyperspace are inaccurate and that "the universe was, in fact, a fractured element, and the rifts and joints between the moving plates drifted across what humans called 'empty' space". On 9 November 2510, the Leviathan-class JumpShip Raiden tried to jump from Salford to Brailsford but misjumped to Kaetetôã instead because of a cosmic rift drifting through the jump point at the time. The Raiden was wrecked in the process. Almost exactly 546 years later, on 7 November 3056, the Scout-class JumpShip Telendine suffered the same fate in an attempt to jump from Salford to a classified destination, also misjumping to Kaetetôã. Since neither ship nor their crews ever made contact with the rest of humanity again, however, this fact remains unknown. Such incidents, however, tend to be used as a deus ex machina by the authors and are poorly supported by "factual" discussions of hyperspace travel, such as in the sourcebooks "DropShips & JumpShips," "BattleSpace," "Explorer Corps," "AeroTech 2nd Edition, Revised," and "Strategic Operations."

In another notable misjump, the WarShip SLS Manassas was suspended in hyperspace for 250 years during a misjump befor appearing at the destination jump point, effectively moving the ship and its crew 250 years into the future. The possibility of this sort of "hyperspace suspended animation" is understood by hyperspace physicists but the "common" thinking (which does not include knowledge of the SLS Manassas) is that it has not been replicated outside of the laboratory .

Emergence

When materializing at their destination point (whether or not it was the intended target of the jump), the JumpShip again causes tidal stresses and also advertises its presence with an electromagnetic pulse that can be detected billions of kilometers away, and an infra-red signature that can be detected from a relatively close range of up to 50,000km. Together these are called the Emergence signature, and are determined by the total mass of the JumpShip and all attached DropShips.

Drive recharging

After a jump, the K-F drive must be recharged, which is a slow and delicate process. The most common way is for the JumpShip to turn its stern towards the sun and deploy its Jump Sail, essentially a huge solar collector resembling a parachute about one kilometer in diameter.

Station keeping thrusters allow the ship to maintain its position and counter the downward drift toward the local star induced from the faint solar gravity. It should be noted that the standard jump points, zenith and nadir points, are not in orbit around the star. They are stationary locations and thus without the station keeping drive, a JumpShip would begin to fall toward the star due to solar gravity. While there is some pressure from sunlight on the "sail," the sail is not a sail in the propulsive sense. The gravity of the star at zenith and nadir jump points is vastly stronger than the pressure of light (and solar wind, which is about 1% as strong as light pressure) so much so that even the lightweight foil material of the sail itself is heavier than the light and solar wind impinging on it. For example, at Sol's zenith and nadir jump points, the inward pull of gravity on the jump sail is 60 times stronger than the outward push of light pressure, while the JumpShip as a whole is more than one hundred thousand times heavier than the push of light pressure.

In this way, the jump drive can be recharged in six to nine days depending on the spectral class of the star. An alternative to the Jump Sail is to recharge the drive with the ship's power plant, but the delicate machinery of the K-F drive does not tolerate such treatment well.

Jump Points sometimes feature Recharging Stations. They can transfer power to a JumpShip if it is docked, or by beaming it at the Jump Sail of the ship for collection. This process still requires 150 hours to fully charge the drive.

Some JumpShips are equipped with a Lithium-Fusion Battery that provides a second charge for the K-F drive right away. The battery can be charged separately from the jump drive, in the same way as the drive itself.

After recharging, the JumpShip is ready to jump again.

Manufacturing

The most common and best known JumpShip types are the Invader and the slightly less common Merchant. The Monolith has the best DropShip capacity (9) of all civilian JumpShips and also of most WarShips; only the huge Potemkin class troop cruiser can carry more DropShips (an unmatched 25).

As of 3055, approximately 3,000 JumpShips operate in the Inner Sphere according to canonical sources (up from some 2,000 in 3025). However, this has been dismissed in recent publications as being inadequate to meet the observed shipping of bulk goods in the Inner Sphere, where there prolific references to planets with populations of billions feeding neighboring worlds, exporting petroleum products and shipping bulk materials like iron ores. These are materials consumed in gigaton quantities on any developed planet with a population in the billions, and obviously cannot be met (for many planets) by the small cargo holds of common freighter DropShips like the Mule and the limited capacity of the Invader and Merchant JumpShips.

Known JumpShip classes include (sorted alphabetically and excluding WarShips):

(See also: Category: JumpShips)

• Chimeisho - 245,000 tons, 2 Hardpoints, introduced in 3056. New design built in the Draconis Combine after reconstruction of the Izumi shipyards at Altair. Notable for being equipped with a L-F Battery.
• Comitatus - 250,000 tons, 1 Hardpoint, introduced in 2995. Doubles as Aerospace Fighter carrier, carrying 25 fighters. Originally conceived by Clan Snow Raven as transport with 4 Hardpoints. In use by Clans only.
• Explorer - 50,000 tons, no Hardpoints, introduced in 2703 as a civilian touring craft.
• Hunter - 95,000 tons, 1 Hardpoint, introduced in 2832. Developed by Clan Ghost Bear as a dedicated scout. Small emergence signature. Equipped with a HPG. In use by Clans only.
• Invader - 152,000 tons, 3 Hardpoints, introduced in 2631. Most common of all JumpShip classes, accounts for over 45% of all registered JumpShips. Sophisticated communications equipment.
• Leviathan - Large JumpShip type from Star League era, specifications unknown. Already in use by 2510, 7+ Hardpoints. Likened to the Odyssey and Monolith classes; smaller than Monolith.
• Magellan - 175,000 tons, 1 Hardpoint, introduced in 2960. Designed and exclusively used by ComStar for their Explorer Corps. Equipped with a HPG.
• Merchant - 120,000 tons, 2 Hardpoints, introduced in 2503. Common class in widespread use, second only to the Invader.
• Monolith - 380,000 tons, 9 Hardpoints, introduced in 2776. Rare. Often used as flagship because of superb command center facilities. Largest civilian JumpShip class ever built.
• Odyssey - 345,000 tons, 4 Hardpoints, introduced in 2887. In use by Clans only.
• Scout - 79,000 tons, 1 Hardpoint, introduced in 2712. Smallest JumpShip class in common use. Designed for exploration. Small emergence signature makes it well suited for stealthy operations.
• Star Lord - 274,000 tons, 6 Hardpoints, introduced in 2590. Docking collars are equipped with grapples that can reel in small DropShips, useful for rescue operations.
• Tramp - 250,000 tons, 3 Hardpoints, introduced in 2754. An uncommon class; also unusual in that they mount defensive weaponry. Superseded by the more popular Star Lord. Clan Nova Cat has refitted some of theirs with a 4th Hardpoint.
• Uma - Specifications unknown. One such ship operated by the DCMS in conjunction with the ComStar Explorer Corps as of 3059