- 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 referred to as "WarShips" instead). This article adresses the former, vastly more common type, while WarShips are covered in their own article.
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 to a different star system, covering 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, namely between planets and jump points, while the large and fragile JumpShip remains at the jump point.
Based on theories of professors Thomas Kearny and Takayoshi Fuchida dating back to the 21st century, functional FTL drives were developed in the Deimos Project which was authorized by the Terran Alliance Parliament in 2103. At 12:00 GMT on September 3, 2107, the Deimos test ship made its maiden voyage, jumping from Sol's Zenith jump point to the Nadir jump point in less than a minute. In February 2108 Raymond Bache was the first human to travel faster than light between Sol's jump points, and in December of the same year the TAS Pathfinder under the command of Norm McKenna made its historic jump to the Tau Ceti system, becoming the first manned faster-than-light interstellar spacecraft.
The first JumpShips carried their DropShips (of up to 5,000 tons) in pressurized internal bays, until jump-compatible Hardpoints for docking became available around 2470. There has been no significant change to the basic form and function of JumpShips since then.
Designed exclusively to provide FTL jump capacity, JumpShips essentially comprise only the essential components required for jumping. The delicate Kearny-Fuchida (K-F) drive dictates the typical needle-like appearance of a JumpShip's fuselage and, together with the trademark Jump Sail that is required to safely recharge the K-F drive with solar energy, accounts for 95% of its mass. 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 have no transit drives, only weak maneuvering thrusters to adjust their position. Other than that, they provide crew quarters and a bridge; other common features include Grav Decks, hydroponic gardens, extra cargo space or hangars for Small Craft.
The theoretical maximum size for civilian JumpShips is 500,000 tons, and 2,500,000 tons for WarShips. K-F drives cannot be smaller than 2,500 tons and the smallest known ship type with jump capacity is the 6,100-ton Bug-Eye-class, a highly specialized military surveillance vessel.
Common JumpShips are unarmed, carrying insignificant weaponry at best, and are typically considered non-combatants. However, the distinction is somewhat blurred, as some JumpShips do possess some level of armor and armament; these are colloquially called Jolly Rogers. 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 military vessels.
JumpShip operations are naturally limited, owing to their narrow performance profile. They do little more than jump. Between jumps they charge their jump drive and wait for DropShips to arrive and dock.
 Jump procedure
 Jump preparation
In order to safely jump, a JumpShip must operate within a zone where gravitational influences drop below the critical level for the hyperspace field of the K-F drive to form properly. These zones are somewhat inaccurately referred to as Jump Points. Typically, JumpShips remain at valid jump points at all times, but some irregular jump points are of a transient nature and might vanish (due to planetary mechanics, for example). In such a case the JumpShip must wait for the jump point to reappear or move to another jump point; it cannot jump otherwise.
The origin and destination of a jump can only be a jump point, although the destination may be any jump point within range, even very close. It is a well-known (but rarely executed) maneuver, for example, to jump from one of a star system's standard jump points to the other. The maximum jump range for K-F drives is held to be 30 light-years, although accidential misjumps have been known to move ships across hundreds of light-years, and possibly much more, in a single jump in rare instances. Experimental drives exist that may jump longer distances than 30 light-years, but none is technically mature enough to be entirely safe to use.
Navigators usually target the standard jump points on the proximity limit above and below the poles of the star as defined by the system's plane of the ecliptic, called the Zenith and Nadir jump point, respectively. These jump points minimize the influence of planetary gravity on jump calculations, making them relatively safe and easy to use. While other non-standard jump points exist within star systems, these are often of a transitory nature and risky to use.
The ship's navigator must feed the navigational calculations (jump solution) into the drive drive controller. Those calculations may take anywhere from ten minutes to twelve hours depending on the circumstances; they 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 can take hours and are much more likely to cause a misjump.
Because the exact data is subject to change (especially for non-standard jump points that depend on the alignment of planetary bodies), ships standing by for jumping have to update their jump solutions regularly. Jump solutions for pirate points may be valid for as little as 20 minutes, while solutions at the Zenith and Nadir points can be valid for months depending on circumstances.
Any DropShips accompanying the JumpShip must be docked and properly secured with KFFC Booms, otherwise the K-F field might mangle them. If a proper connection cannot be confirmed, the K-F drive controller normally prevents or aborts a jump attempt.
Although not technically a necessity for jumping, the JumpShip should also have furled its Jump Sail and confirmed that no other craft are within twenty-seven kilometers for safety reasons when executing a jump.
When the jump program is initiated, it becomes impossible to abort the jump process except by the safety systems of the drive itself.
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 presence of another K-F drive coil, even a damaged one, within a certain proximity inhibits the correct formation of a K-F field. It is therefore impossible to move (jump) a fully assembled K-F drive as cargo or to recover a stranded JumpShip; unless they elect to scrap their drive coil, they must jump under their own power.
The K-F field only correctly encompasses objects within the JumpShip or a DropShip that is properly connected by a KFFC Boom, and may slice through or mangle objects that are not fully encompassed. Firing the K-F drive causes tidal stresses that can be felt up to 27 kilometers away from the JumpShip.
It is possible to jump while moving; a JumpShip is not required to be stationary relative to the jump point. This is especially important for WarShips as it allows them to jump even while maneuvering under full thrust.
Passengers typically suffer mild dizziness from jumping. Some even suffer serious nausea (Transition-disorientation-syndrome or TDS) for some time after a jump, in a fashion similar to sea-sickness.
Damaged components of the K-F 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.
When materializing at their destination point (whether or not it was the intended destination of the jump), the JumpShip causes tidal stresses similar to those caused when jumping. It 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 50,000 km. Together these are called the Emergence signature, and are determined by the total mass of the JumpShip and all attached DropShips. It is even possible to assess the mass or size of an arriving JumpShip from its emergence signature.
While a JumpShip may be in motion relative to the origin jump point, it always arrives "stationary" relative to the jump point. A somewhat inaccurate description is that being pulled through a jump takes the momentum out of any mass. To be exact, the ship matches the motion (vector and velocity, or even orbital path) of the destination jump point upon emergence. In the case of the Kaetetôã misjumps, the JumpShips found they were approaching the planet at 700,000 km/h.
The ship's alignment does not change during the jump, but it is possible for the navigator to make the ship turn while jumping, altering its alignment as desired.
 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 at the jump point and counter the downward drift toward the local star induced from the faint solar gravity at the standard (zenith and nadir) jump points which are stationary locations, not stable orbits.
- Some older publications (not all) suggested that a JumpShip would point its nose towards the sun and deploy the sail behind it, and then use the thrusters to counter the gentle drift induced on the sail by light pressure and/or solar wind. After consideration of the conflicting examples and evaluation of the relevant forces involved, the conflicting orientations were standardized in Aerotech 2nd edition, Revised, to have the JumpShip's stern point toward the star. This was because 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 alone 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.
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.
Almost all jump points used to feature Recharging Stations, but many of these have been destroyed over the course of the Succession Wars. Recharge stations can transfer power to a JumpShip if it is docked, or by beaming it at the Jump Sail of the ship for collection. This microwave transfer process still requires 176 hours to fully charge the drive to avoid KF drive damage, though recharging can be shortened if the JumpShip docks physically with the station. The station collects power through its own solar sail, and stores it on batteries; these should not be confused with Lithium-Fusion Batteries, however.
After recharging, the JumpShip is ready to jump again.
A misjump can occur because of miscalculations, technical problems or spatial anomalies, causing the JumpShip to deviate from its intended destination and emerge off course and often also causing damage to the K-F drive in the process. Errors are typically in terms of kilometers or astronomical units, but misjumps of light-years have occurred. Sometimes ships 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 threshold of 30 light-years in rare instances: The accidental discovery of Alfirk occurred due to a misjump that carried the ship across several hundred light-years in a single (mis-)jump; similarly, the wreckage of the Liberator was found over 350 light-years from its last known position. However, such long-range misjumps require very unusual astronomical conditions.
In another notable misjump, the WarShip SLS Manassas was suspended in hyperspace for 250 years during a misjump before 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.
Spatial anomalies are far rarer, but are suspected to have caused the loss of several JumpShips over the millennium of their use. It has been explained that, because of the JumpShip's limited meteoritic shielding, occasionally "something in the doorway could cause an accident" during jumping. Evidently, spatial anomalies, while astronomically rare, are not entirely random. 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 crew ever made contact with the rest of humanity again, however, this fact remains unknown within the BattleTech universe.
Inherent mechanics ensure that JumpShips rarely jump deep into the gravity well of a star or planet. This usually only occurs 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. However, if a JumpShip attempts to depart from or arrive at a non-valid jump point, the ship as a whole will receive massive damage as the hyperspace field forms improperly, causing the ship and crew to arrive in warped and mangled state. Any survivors are likely to suffer permanent injuries in most or all organs, skeleton, and muscles.
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 older 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 are 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. The actual number of JumpShips is presumably closer to 30,000.
Known JumpShip classes include (sorted alphabetically and excluding WarShips):
- (See also: Category:JumpShip classes)
- 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. Became almost extinct in the Succession Wars.
- 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 predating the 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 its 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. 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. Uncommon class; also unusual in that they mount defensive weaponry. Superseded by the more popular Star Lord. Clan Nova Cat reported to operate some with a 4th Hardpoint.
- Uma - Specifications unknown. One such ship operated by the DCMS in conjunction with the ComStar Explorer Corps as of 3059
- ↑ Mercenaries Supplemental II, p. 85
- ↑ Strategic Operations, pp. 134-135
- ↑ Strategic Operations, pp. 88-89
- ↑ Binding Force, p. 139
- ↑ Strategic Operations, p. 90
- ↑ Binding Force, p. 31
- ↑ Strategic Operations, p. 89
- ↑ AeroTech 2 Revised Edition, p. 52
- ↑ Binding Force, p. 31
- ↑ Strategic Operations, p. 131
- ↑ AeroTech 2 Revised, pp. 116-117
- ↑ Strategic Operations, p. 124
- ↑ Strategic Operations, p. 131
- ↑ Strategic Operations, p.134
- ↑ Strategic Operations, p. 88-89
- ↑ Far Country, p. 16
- ↑ Far Country, p. 16
- ↑ Mercenary's Handbook 3055, p. 23
- ↑ DropShips and JumpShips, p.??
- ↑ Strategic Operations, p. 251
- ↑ Handbook: House Davion, p. 96