Editing Propulsion in the Re-imagined Series

{{disline|For information on the [[Battlestar Galactica (TOS)|Original Series]] modes of propulsion, see [[Propulsion (TOS)]].}}

{{RDM science series}}
In the [[Re-imagined Series]], propulsion systems are powered by fuel refined from [[tylium (RDM)|tylium ore]]. A ship's primary propulsion systems, referred to as "sublight engines," allow it to travel at a slight fraction of the speed of light, which is sufficient to traverse the distances between planets in a solar system in relatively short timeframes.  Most ships in the series also have a secondary system, called a [[Propulsion in the Re-imagined Series#Faster-Than-Light travel|'''faster-than-light drive''']] (or '''"FTL"'''), that enables a ship to travel interstellar distances almost instantaneously, by "folding up space" in between the ship and its destination. Since, under normal circumstances, a ship that has used its FTL drive cannot be followed without explicit information about its destination, this technology is used extensively in strategic and tactical maneuvers. 

==Sublight propulsion==

In the Re-imagined Series, all ships have some manner of sublight flight ability. Sublight propulsion is convenient for intra-solar system travel (such as to or from the planets that comprise the [[The Twelve Colonies of Kobol|Twelve Colonies]]), but cannot be used for travel outside of a solar system as the time to arrive at a destination may exceed the fuel supply of the ship or the lifetime of the crew that fly the ship.

As many of the ships of the [[The Fleet (RDM)|Fleet]] are capable of landing on and taking off from planets, (such as [[New Caprica]]) it is clear that sublight engines work in an atmosphere as well as in space. ''Galactica'' is never seen doing this, and its large mass might prohibit planetary landings altogether, but it employs sublight engines for normal spaceflight. Few of the ships appear to have extremely large propellant tanks as would be required for rocketry as it is presently understood, in spite of having aft-mounted thrusters. This may be explained by the very high energy density of [[tylium (RDM)|tylium]] fuel. Smaller vessels are known to employ rocketry-based [[Navigation in the Re-imagined Series|RCS thrusters]] for maneuvering and small course adjustments.

Vipers are equipped with a thrust reversal system to counteract or arrest their forward momentum {{TRS|The Hand of God (RDM)}}. No such mechanism exists on capital ships, but such vessels might turn by 180° to decelerate.
 
Cylons [[Basestar (RDM)|baseships]] do not have any visible exhaust nozzles or other external structural mechanisms that suggest propulsion ability. It is possible that force fields of the [[Gravity in the Re-imagined Series|artificial gravity]] generators are the source of the sublight propulsion. 

Both Colonial {{TRS|Hero}} and Cylon missiles used in combat appear to be rockets, leaving a trail of gas behind them.

The law of conservation of momentum requires that any propulsion system which adds momentum to a spacecraft or missile in one direction must equal the amount of momentum that is imparted in the opposite direction to something else, as in the example of the controlled combustion of rocket fuel creating thrust in the opposite direction of a ship's or missile's movement. ''{{RDM|Pegasus}}'', for example, possesses two very large thrusters on the bow of the ship to counteract the force of the main engines {{TRS|Razor}}. However, many other vessels don't appear to have such thrusters.

===Relativistic Sublight travel ===
The [[Thirteenth Tribe (RDM)|Thirteenth Tribe]] did not have jump drive technology, so FTL travel was unavailable to the [[Final Five]] on their voyage from [[Earth (RDM)|Earth]] to the [[Twelve Colonies of Kobol|Twelve Colonies]]. They instead used a sublight drive able to reach relativistic speeds (a substantial fraction of the speed of light.)  The journey took about 2,000 years according to a planetary reference frame, but a more modest (unspecified) number of years in their ship's reference frame.

==Faster-Than-Light travel==
[[File:FTL1.jpg|thumb|''Galactica'' FTL jump.]]
''FTL'' is an abbreviation for '''F'''aster-'''T'''han-'''L'''ight.  The term refers to a means of interstellar propulsion utilized by the [[Cylons (RDM)|Cylons]] and the [[The Twelve Colonies of Kobol|Colonials]]. A common shorthand term for FTL travel is '''"jumping"''', as this  space-folding drive involves making instantaneous "jumps" across vast distances in space.<ref>http://www.scifi.com/battlestar/about/index.php?sub=glossary</ref>

[[File:Basestar FTL Jump The Plan.png|thumb|Basestar FTL jump.]]

The FTL drive makes interstellar travel possible for both the Colonials and Cylons.  No longer confined to their own home solar system, the Cylons managed to avoid Colonial interference for forty years after the [[Cylon War]] and establish their own [[Cylon homeworld|homeworld]].  However, not all ships &mdash; from small to large &mdash; are outfitted with these drives {{TRS|Miniseries, Night 2}}. 

It is likely that FTL drives are not commonplace on many civilian ships because of the costs involved in using and maintaining the drive and the amount of [[tylium (RDM)|fuel]] available. For some civilian ships that travel comparatively short distances between some destinations, such as the ill-fated [[Botanical Cruiser]], FTL may simply be impractical or unnecessary.

The technology behind FTL systems is such that, providing the relevant data is known (how that data is acquired, for instance how ships can determine what obstacles are present at their destination, despite never having traveled there before, is not known, though it is suggested long-range telescopes are involved) ships can jump with a high degree of accuracy, allowing ships to rendezvous in space and even "park" in a synchronous orbit directly above a given point on a planet's surface {{TRS|Miniseries, Night 2}}. Proper FTL use even enables vessels to arrive in crowded areas, such as the middle of an asteroid field or other ships, without the risk of collision and damage {{TRS|The Hand of God (RDM)}}. What happens if a ship jumps to the same point at the same time as another ship, or jumps to a point occupied by another ship, is unknown.

[[File:Ftl_display.jpg|thumb|FTL drive display]]

Little specific information on the technology of an FTL drive has been given in the Miniseries or regular series. We know only that ''Galactica'' has two FTL drives<ref>Dialogue from Colonel [[Saul Tigh|Tigh]] to Lt. [[Felix Gaeta|Gaeta]] instructs the tactical officer to "spin up FTL drives 1 and 2" in the [[Miniseries, Night 2]].</ref>, and that other smaller or civilian ships have a single drive. Ships also do not need to be in motion for the FTL drive to work, or at least smaller craft do not need to be, as Raptors during the Battle of the Colony jump directly from Galactica's starboard flight pod without engaging in forward momentum.

FTL drives on ''Galactica'' are said to be "spun up" in preparation for a jump, contain components such as the "spinner" {{TRS|The Captain's Hand}} and "spin-sync generator" {{TRS|Faith}} and display a rotational and possibly electromagnetic operation. Until the final-season episode "[[Blood on the Scales]]," the expression was theorized by many fans to be either a turn of phrase, or an anachronism dating back to another form of propulsion, much like the use of the term "air" in reference to fighter operations in the vacuum of space ("[[Commander Air Group]]," "[[Combat Air Patrol]]," ''inter alia'') and the real-world use of "sail" and "set sail" in reference to self-propelled vessels.

[[File:Ftl2.jpg|thumb|''Galactica'''s FTL drive.]]

An operational FTL drive was first seen in "Blood on the Scales," specifically one of ''Galactica''{{'|s}} two. Indeed, an assortment of long, thick shafts spin as part of the FTL drive mechanism.  The FTL engine room includes a control terminal for diagnostic and auxiliary control.  In order to prevent Felix Gaeta and his mutineers from jumping ''Galactica'' to an unknown location, former Senior Chief Petty Officer [[Galen Tyrol]] attempted to log into the engine room terminal which refused him access, recognizing his duty status as "inactive".  He was nevertheless able to manually disable the drive by removing the synchronization coil.<ref>Part identified in dialogue in "No Exit".</ref>  Gaeta made no attempt to use the other FTL drive, indicating either that the other drive was inoperative, the two drives are not entirely independent, that neither drive alone is sufficient to jump the ship, or that Gaeta simply decided that the mutiny and coup d'état were doomed and further attempts were pointless. However, the Battle of New Caprica demonstrates that a ship of Galactica's class, the Jupiter-class is capable of performing two short-range FTL "hops" before requiring new jump calculations; Galactica jumps once into freefall of the atmosphere of New Caprica, then is able to jump back into orbit before impacting the ground, although if this is due to the two FTL drives containing enough energy for one independent short-range jump apiece, or distance being a factor in jump calculation and energy expenditure (a short "hop" requires less energy and fuel for the FTL drive versus a jump of several light years).

FTL jump drives can be used ''within'' an atmosphere. This Colonial tactic is used often to evade Cylon detection. While [[Raptor]]s primarily perform these kind of jumps, Admiral [[William Adama]] performs a daring intra-atmosphere jump at approximately 100,000 feet altitude with ''{{RDM|Galactica}}'' during the [[Battle of New Caprica]] to evade immediate Cylon detection. The battlestar jumps back to space a few thousand feet above the planet's surface after its Viper deployment.  When ''Galactica'' jumps, the clouds surrounding it and the re-entry fires consuming its hull are "sucked" into the vacuum created by the sudden loss of volume. A clap of thunder is heard afterward, likely caused by air rushing into the aforementioned vacuum {{TRS|Exodus, Part II}}. A similar phenomenon occurs when ''Pegasus'' jumps from the attack on the [[Scorpion Fleet Shipyards]]; the resulting displacement not only draws in the burning gases from the nearby berthing superstructure, but also defuses two nuclear warheads bound for ''Pegasus'' itself {{TRS|Razor}}.

[[File:Ftl3.jpg|thumb|''Galactica'''s engine room.]]

An area of spatial distortion of some sort is also produced when a ship jumps.  This effect has been observed twice thus far.  Once, when the tylium refinery ship ''[[Hitei Kan]]'' is approached by a pair of Vipers and a Raptor in an effort to quell a mutiny aboard the ship. The ''Hitei Kan'' unexpectedly jumps and the Vipers and Raptor are repelled away by some force as soon as the ship dematerializes {{TRS|A Disquiet Follows My Soul}}.  The second time this is seen is when a Raptor stolen by [[Sharon Valerii|Sharon "Boomer" Valerii]] executes a jump mere meters away from ''Galactica’s'' hull.  When the Raptor disappears into the jump the section of the hull it was adjacent to is instantaneously indented.  Just prior to that, Col. [[Saul Tigh]] expresses his fears of even greater damage should Valerii jump the Raptor while inside ''Galactica’s'' flight pod {{TRS|Someone to Watch Over Me}}.  During the [[Battle of the Colony]], several Raptors actually do jump within ''Galactica’s'' sealed off starboard flight pod, causing significant damage to the landing bay within the pod and most likely contributed to the catastrophic failure of its hull after the battle {{TRS|Daybreak, Part II}}.  It is not clear how this distortion field, which seems to produce effects like a shock wave, also coincides with the known effect of a jump acting as a sort of vacuum, which instead of producing an outwards wave should pull the surrounding space into it. The two effects might occur consecutively, the vacuum effect left in the ship's wake, then the expelled shock wave, as hangar equipment in the flight pod is seen being pulled towards the vacuum before being expelled outwards.

Later, the Fleet's FTL drives are upgraded by the Rebel Cylons so they can now travel as far and as fast as a Cylon ship.  Not all ships are apparently upgraded as for some reason, the Raptor Boomer steals lacks the upgraded drive.

=== Limitations of Colonial FTL ===

* The effectiveness of a [[Raptor]]'s FTL is limited to brief, short-distance jumps. Raptors require a sequence of short consecutive FTL "hops" to reach the same destination as a Colonial capital ship with a full-sized FTL drive {{TRS|Miniseries, Night 2}}.
* Colonial FTL systems are prone to breakdown after repetitive use over an extended period of time {{TRS|33}}.
* Colonial FTL systems appear to be a holdover from the [[History of the Twelve Colonies#Exodus|Exodus]] from {{RDM|Kobol}}, and their current designs have been developed to meet the needs of jumping between the [[The Twelve Colonies of Kobol|Twelve Colonies]], and their outposts in other star systems. Colonial FTL capabilities are generally limited in effective range compared to Cylon FTL.
* Colonial FTL computers are prone to glitches, often jumping ships to the wrong coordinates {{TRS|Lay Down Your Burdens, Part I}}.
* Navigators must be careful to plan FTL jump paths in order to keep a safe distance from planets or other large objects ([[TRS]]: "[[Kobol's Last Gleaming, Part I]]").
* "Spooling up" a Colonial FTL drive takes at least 20 minutes when the drive has been offline {{TRS|Crossroads Part II}}. Because of this, when ships enter dangerous situations, they keep their FTL drives "spun up". Drives cannot be kept spun up indefinitely, as system crashes or serious damage to the drive will occur. A "cooldown" time is required after a jump for new jump calculations, so a ship that has jumped into a new location cannot jump to another location for a brief period of time.
* Colonial capital ships (at least older ones of ''Galactica'' type) require the flight pods to retract before a jump, prolonging jump prep time. Should the ship jump with extended pods, serious structural damage can occur.

Colonial FTL performance can be improved, demonstrated when a [[Raptor]] is successfully refitted by a team apparently led by Lieutenant [[Felix Gaeta]] with the navigational computer from a captured [[Heavy Raider]] (presumably the one used by [[Kara Thrace]] to return from Caprica in "[[Home, Part I]]") and, with the cooperation of a [[Sharon Agathon|Number Eight]], is used to navigate a squadron of Raptors back to Caprica on a rescue mission to retrieve a [[Caprica Resistance|group of resistance fighters]] {{TRS|Lay Down Your Burdens, Part I}}. A massive distance that would have taken Galactica 241 jumps one way (~482 jumps total), the Raptor squadron does in only 20 (10 to Caprica, 10 back).

Colonial FTL computers can be affected by highly-charged sub-atomic particles, corrupting their calculations and possibly causing a jump beyond the [[Red Line]], as in the case of [[Raptor 718]] ([[TRS]]: "[[The Face of the Enemy]]," Episode 2).

The FTL drive apparently puts significant strain on a ship's structure.  ''Galactica'' has substantial cracks in its hull adjacent to the FTL drive which Tyrol disabled. {{TRS|Blood on the Scales}}  While discussing structural repairs with Adm. Adama, Tyrol asks him not to jump the ship for a while, while his crews upgrade the structure. {{TRS|No Exit}}

FTL jumps can apparently induce nausea or discomfort in some people, such as [[Cally Henderson]] ([[TRS]]: [[Miniseries, Night 2]], "[[Kobol's Last Gleaming, Part I]]").

=== Cylon Advantages in FTL ===

* Cylon FTL systems can be manufactured to be much more compact than their Colonial equivalent, thus allowing the [[Cylon Raider]] to be outfitted with an FTL drive. {{TRS|Miniseries, Night 2}}.
* Cylon FTL drive systems are far more efficient than their Colonial equivalent. Tests with the Raider captured by the [[Battlestar]] ''{{RDM|Galactica}}'' {{TRS|You Can't Go Home Again}} demonstrated that the drive could enable the Raider to jump directly from the vicinity of {{RDM|Kobol}} back to [[Caprica (RDM)|Caprica]] ([[TRS]]: "[[Kobol's Last Gleaming, Part I]]") - a jump completed by Lieutenant [[Kara Thrace]] during her search for the [[Arrow of Apollo]] ([[TRS]]: "[[Kobol's Last Gleaming, Part II]]"). This superiority is not from FTL drives themselves, but from the superior Cylon navigation system, resulting in more accurate jump calculations.

Using the most conservative estimate, Cylon FTL drives are three times more efficient than their Colonial counterparts {{TRS|A Disquiet Follows My Soul}}.  Despite being well-versed in maintaining ''Galactica'''s two FTL drives and being a [[Final Five]] [[Cylon]], former [[wikipedia:Senior Chief Petty Officer|Senior Chief Petty Officer]] [[Galen Tyrol]] is baffled by Cylon FTL technology and defers to "[[Number Six|Sixes]], [[Number Eight|Sharons]] and maybe even some [[Number Two|Leobens]]" to upgrade Colonial ships' drives. The Fleet later receives the upgrade and the difference can be clearly seen in the jump capabilities: a Raptor stolen by Boomer which does not have the upgraded drive takes over a dozen jumps to reach the Colony, but ''Galactica'' and an upgraded Raptor are both able to cover the same distance in one {{TRS|Someone to Watch Over Me|Islanded in a Stream of Stars|Daybreak, Part II}}.

==FTL jump ranges==
The range that ''Galactica'' can jump at has never been specified on-screen. However, in a deleted line from the mini-series the jump from Ragnar to the [[Prolmar Sector]] is said to be "30 light-years"<ref>[http://web.archive.org/web/20060517022749/http://www.curemode.com/battlestar/bgarticle26.htm An early draft of the mini-series script]</ref>, which is well beyond the [[red line]] (maximum safely calculable jump range). This is consistent with Colonel Tigh saying that ''Galactica'' could search every planet within 12 light-years for water before having to jump to another sector altogether {{TRS|Water}}. On this Wiki, producer Bradley Thompson suggested that internally, the writers had been working on the idea the Fleet had been jumping about 5 light-years at a time, although that does not have to have been its maximum range. Finally, on composer Bear McCreary's blog<ref>[http://www.bearmccreary.com/blog/?p=1760 Bear McCreary's blog]</ref>, science advisor Kevin Grazier and producer Bradley Thompson suggested that the final six digits for the jump coordinates Kara interprets from [[the Music]] represent distance in [[SU]]s. 999,999 SUs - the maximum possible distance that can be inputted - would relate to 15.812 Colonial light-years. The distance inputted during the Battle of the Colony is 365,321 SU or 5.77 Colonial light-years, which is presumably the distance from the Colony to Earth {{TRS|Daybreak, Part II}}. There may also be a factoring scale at work, and at close ranges ''Galactica'' appears to be able to jump much more accurately, as demonstrated by its jump from several million kilometers directly into New Caprica's atmosphere 100,000 feet above the surface {{TRS|Exodus, Part II}}, or a jump of unknown range to within one kilometre of the Colony's surface {{TRS|Daybreak, Part II}}.

Cylon FTL ranges are considerably larger. At the end of the series, the Fleet's larger ships have their jump ranges tripled by the installation of Cylon technology {{TRS|A Disquiet Follows My Soul}}. However, during the rescue of Colonial resistance forces from Caprica three years earlier, a Raptor squadron outfitted with a Cylon FTL navigation computer traversed in 10 jumps {{TRS|Lay Down Your Burdens, Part I}} a distance that ''Galactica'' would have required a minimum of 230 jumps (conservatively) to cross {{TRS|Pegasus (Extended Version)|Pegasus}}, an improvement by a factor of 23.  However, this rescue team was just using the navigation computer to improve their jump calculations.  Another example is how many jumps it ended up taking to reach The Colony.  When Boomer stole a for some reason un-upgraded Raptor, it took her over a dozen jumps to reach The Colony.  But the recon Raptor that was dispatched and even ''Galactica'' herself were able to make that distance in ''one'' jump with their upgraded FTL drives.  Lee Adama even specifically said that The Colony was in ''Galactica''{{'|s}} FTL range which it would not have been before with the un-upgraded drive given Boomer's journey there.  With the upgraded drives, Tyrol said that the efficiency of the Fleet's jump drive would be tripled and give them a much longer jump range which they believed was key to finding a new world for humanity to settle on.  Cylon FTL's were so complicated that even Tyrol did not understand them fully and said they were going to need rebel Cylons just to do the upgrades.

==Background to FTL in the Re-imagined Series==

{{Plausible speculation}}

In establishing the series the creators of the [[Battlestar Galactica (RDM)|Re-imagined Series]] determined to keep everything within the show very "[[Naturalistic science fiction|natural]]". This means steering away from the standard clichés of television science-fiction: no bumpy-head aliens, no remarkable technology such as matter/anti-matter conversion, etc. So how is the concept of faster-than-light travel possible within this precept?

===Underpinning Theories===

[[File:Wormhole-demo.png|thumb|FTL: "Folding Space"]]
The FTL drive technology used within the Re-imagined Series might be based on the use of [[Wikipedia:Superstring Theory|Superstring Theory]] and [[Wikipedia:M-Theory|M-Theory]] that essentially enable the "jump drive" systems to "fold" space, reducing the distance between any two points by creating a "corridor" through space that links them together (essentially forming a wormhole, or Einstein-Rosen Bridge). Such "corridors" are allowed by the general theory of relativity; what [[Wikipedia:M-Theory|M-Theory]] does is provide a way to change the topology of space-time dynamically.

The use of such wormholes is based on the tenet that space is curved. Hence the term "[[Wikipedia:Wormhole|wormhole]]," which arises from the analogy that space can be seen as an apple. A worm can travel from one side of the apple to the other in two ways:
* By crawling over the surface, or
* By burrowing through the apple (creating a "wormhole").
Obviously, the second option is considerably shorter than the first.

===Relativistic Acceleration===
A key point concerning the use of wormholes within the new ''Battlestar Galactica'' is that they do not break the fundamental limiting factor of our universe: the speed of light. Vessels in ''Battlestar Galactica'' do not accelerate to faster-than-light velocities. Rather, they use the wormhole to reduce the distance to their destination, thus giving the ''impression'' of faster-than-light travel. 

However, the FTL jumps in the series do allow information to be sent faster than light can send it, which results in a violation of causality within the special theory of relativity (i.e. If event A comes before B from one viewpoint, there will be other equally valid viewpoints where event B takes place before A). Causality is not violated by FTL in a universe that has a special fixed reference frame, however this contradicts current understanding.

This is the reason why FTL jumps are virtually instantaneous within episodes. It also means that the only ''direct'' form of propulsion available for vessels is generated by their [[Sublight Propulsion|sublight drive systems]]<ref>In turn, this is why vessels exiting from a jump are traveling at the same velocity as when they committed to the jump ([[TRS]]: [[Miniseries, Night 2]], "[[33]]," "[[The Hand of God (RDM)|The Hand of God]]" and other episodes).</ref>.

===Feasibility===
While the use of wormholes in this manner is not currently possible, work is progressing on superstring and M-Theory which may make the creation of wormholes possible in the future. The limiting factor is the ability to generate negative energy densities, which are allowed (though severely restricted) by quantum mechanics. As such, the use of such systems again meets one of the stated desires of the the producers of ''Battlestar Galactica'': not to rely on the "traditional" trappings of science-fiction that require exotic science and technology. Theoretical physicist [[Wikipedia:Kip Thorne|Kip Thorne]] has carried out extensive research into wormholes, and helped develop a scientifically-consistent means of wormhole travel used by [[Wikipedia:Carl Sagan|Carl Sagan]] in his novel [[Wikipedia:Contact (novel)|"Contact"]] which bears a remarkable similarity to the technology employed within ''Battlestar Galactica''.

==See Also==
*[[Combat jump]]
*[[List of terms (RDM)|List of terms in the Re-imagined Series]]

Spacecraft with sublight flight ability are typically small military vehicles or civilian ships, such the [[Viper (RDM)|Viper]] fighter craft or the [[Botanical Cruiser]] ([[Miniseries]]).

==References==
{{reflist}}
== External links ==
* [[Wikipedia:FTL (Battlestar Galactica)|FTL]] at Wikipedia.
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