Difference between revisions of "Jool"
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| − | + | '''Jool''' is a [[w:Gas giant|gas giant]] and the sixth planet of the [[Kerbol]] star system. It is the [[w:Jupiter|Jupiter]] analog for Kerbal Space Program. Aside from Kerbol, Jool has the largest diameter and greatest mass of all celestial bodies. Its extremely high gravity makes orbital maneuvers unpleasantly expensive. While its distance from [[Kerbin]] makes it difficult to reach, it is one of the most appealing targets for missions due to its large and complex system of five moons: '''[[Laythe]]''', '''[[Vall]]''', '''[[Tylo]]''', '''[[Bop]]''', and '''[[Pol]]'''. It was possible to land and plant flags on Jool<ref>“[http://www.youtube.com/watch?v=WriMi5R72Pc Kerbal Space Program: Planting a Flag on Jool]” by Dahud Lefthanded in version 0.20<!--end flight button was removed in 0.21 , flag planting was added in 0.20--></ref> before v0.23. In versions following 0.23, the craft won't stop at an altitude of -100 m, instead it will continue descending until it gets to -250 m. At this point, anything that hits this altitude at any speed will be completely destroyed. Jool has animated eddies and vortices in [https://www.youtube.com/watch?v=XYV2hOaRQ3M&list=PLEvk9C6Wg5V-XHTRo4CPLAkywoIsD1148&index=3/ high quality.] | |
| − | + | == In-game description == | |
| − | '''Jool''' is a [[w:Gas giant|gas giant]] and the sixth planet of the [[Kerbol]] star system. It is the [[w:Jupiter|Jupiter]] analog for Kerbal Space Program. Aside from Kerbol, Jool has the largest diameter and greatest mass of all celestial bodies. Its extremely high gravity makes orbital maneuvers unpleasantly expensive. While its distance from [[Kerbin]] makes it difficult to reach, it is one of the most appealing targets for missions due to its large and complex system of five moons: '''[[Laythe]]''', '''[[Vall]]''', '''[[Tylo]]''', '''[[Bop]]''', and '''[[Pol]]'''. It was possible to land and plant flags on Jool<ref>“[http://www.youtube.com/watch?v=WriMi5R72Pc Kerbal Space Program: Planting a Flag on Jool]” by Dahud Lefthanded in version 0.20<!--end flight button was removed in 0.21 , flag planting was added in 0.20--></ref> before v0.23. In versions following 0.23, the craft won't stop at an altitude of -100 m, instead it will continue descending until it gets to -250 m. At this point, anything that hits this altitude at any speed will be completely destroyed. Jool has animated eddies and vortices in [https://www.youtube.com/watch?v=XYV2hOaRQ3M&list=PLEvk9C6Wg5V-XHTRo4CPLAkywoIsD1148&index=3/ high quality.] | + | {{Quote |
| − | + | |Jool is particularly known for being a rather large, predominantly green planet. Kerbalkind has longed to visit it since it was first spotted in the sky. Philosophers reason that the swirling green planet must be a really nice place to visit, on account of its wholesome coloration.<br /> | |
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| − | == In-game description == | ||
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| − | |Jool is particularly known for being a rather large, predominantly green planet. Kerbalkind has longed to visit it since it was first spotted in the sky. Philosophers reason that the swirling green planet must be a really nice place to visit, on account of its wholesome coloration.<br /> | ||
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''If you look at Jool through a telescope, it is fuzzy.'' | ''If you look at Jool through a telescope, it is fuzzy.'' | ||
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|[[Kerbal Astronomical Society]]}} | |[[Kerbal Astronomical Society]]}} | ||
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== Atmosphere == | == Atmosphere == | ||
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[[File:Jool_Atmosphere_T&P.png|thumbnail|left|Temperature and pressure of Jool's atmosphere as a function of altitude.]] | [[File:Jool_Atmosphere_T&P.png|thumbnail|left|Temperature and pressure of Jool's atmosphere as a function of altitude.]] | ||
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Jool has an extremely dense, cold [[atmosphere]] with a mass of approximately 8.8×10<sup>19</sup> kilograms (about one ten-millionth that of Jupiter), a datum level pressure of 5066.25 kilopascals (50 atmospheres), and a depth of 200,000 meters. Compared to the atmosphere of [[Kerbin]], Jool's atmosphere has 1875 times the mass, 50 times the surface pressure, and nearly 3 times the depth. At an altitude of 91,554 m on Jool, the atmospheric pressure is the same as at sea level on Kerbin (1 atm). | Jool has an extremely dense, cold [[atmosphere]] with a mass of approximately 8.8×10<sup>19</sup> kilograms (about one ten-millionth that of Jupiter), a datum level pressure of 5066.25 kilopascals (50 atmospheres), and a depth of 200,000 meters. Compared to the atmosphere of [[Kerbin]], Jool's atmosphere has 1875 times the mass, 50 times the surface pressure, and nearly 3 times the depth. At an altitude of 91,554 m on Jool, the atmospheric pressure is the same as at sea level on Kerbin (1 atm). | ||
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The average [[w:Molecular mass|molecular weight]] of Jool air is 2.2 g/mol, and its [[w:Heat capacity ratio|adiabatic index]] is 1.43. Although the composition of Jool's atmosphere is unknown, these values suggest that it consists mostly of hydrogen and helium. The molar mass of Jool's atmosphere is comparable to the real life planet [[w:Jupiter|Jupiter]]. Because of the low molar weight, Jool air at the datum level is only about 2 times as dense as Kerbin air at sea level. | The average [[w:Molecular mass|molecular weight]] of Jool air is 2.2 g/mol, and its [[w:Heat capacity ratio|adiabatic index]] is 1.43. Although the composition of Jool's atmosphere is unknown, these values suggest that it consists mostly of hydrogen and helium. The molar mass of Jool's atmosphere is comparable to the real life planet [[w:Jupiter|Jupiter]]. Because of the low molar weight, Jool air at the datum level is only about 2 times as dense as Kerbin air at sea level. | ||
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Like all other atmospheres in the game, Jool's atmosphere fades exponentially as altitude increases. The [[w:Scale height|scale height]] varies with altitude, which is a change from pre-1.0 [[Version history|versions]] of the game. The pressure-altitude profile is globally constant and independent of temperature. The following table gives the atmospheric pressure at various altitudes above the datum level. | Like all other atmospheres in the game, Jool's atmosphere fades exponentially as altitude increases. The [[w:Scale height|scale height]] varies with altitude, which is a change from pre-1.0 [[Version history|versions]] of the game. The pressure-altitude profile is globally constant and independent of temperature. The following table gives the atmospheric pressure at various altitudes above the datum level. | ||
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{| class="wikitable" | {| class="wikitable" | ||
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! Altitude (m) !! Pressure (Pa) !! Pressure (atm) | ! Altitude (m) !! Pressure (Pa) !! Pressure (atm) | ||
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| 0 || 5 066 250 || 50.000 | | 0 || 5 066 250 || 50.000 | ||
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| 10 000 || 1 519 875 || 15.000 | | 10 000 || 1 519 875 || 15.000 | ||
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| 20 000 || 772 776 || 7.627 | | 20 000 || 772 776 || 7.627 | ||
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| 30 000 || 613 670 || 6.056 | | 30 000 || 613 670 || 6.056 | ||
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| 40 000 || 482 628 || 4.763 | | 40 000 || 482 628 || 4.763 | ||
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| 50 000 || 373 138 || 3.683 | | 50 000 || 373 138 || 3.683 | ||
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| 60 000 || 283 031 || 2.793 | | 60 000 || 283 031 || 2.793 | ||
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| 70 000 || 210 136 || 2.074 | | 70 000 || 210 136 || 2.074 | ||
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| 80 000 || 152 282 || 1.503 | | 80 000 || 152 282 || 1.503 | ||
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| 90 000 || 107 299 || 1.059 | | 90 000 || 107 299 || 1.059 | ||
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| 100 000 || 73 016 || 0.721 | | 100 000 || 73 016 || 0.721 | ||
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| 110 000 || 47 263 || 0.466 | | 110 000 || 47 263 || 0.466 | ||
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| 120 000 || 27 869 || 0.275 | | 120 000 || 27 869 || 0.275 | ||
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| 130 000 || 13 529 || 0.134 | | 130 000 || 13 529 || 0.134 | ||
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| 140 000 || 5 319 || 0.052 | | 140 000 || 5 319 || 0.052 | ||
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| 150 000 || 2 000 || 0.020 | | 150 000 || 2 000 || 0.020 | ||
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| − | | 160 000 || 734.7 || 0.007 | + | | 160 000 || 734.7 || 0.007 |
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| 170 000 || 100.0 || 0.001 | | 170 000 || 100.0 || 0.001 | ||
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| 180 000 || 29.57 || 0.000 | | 180 000 || 29.57 || 0.000 | ||
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| 190 000 || 3.675 || 0.000 | | 190 000 || 3.675 || 0.000 | ||
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| 200 000 || 0 || 0.000 | | 200 000 || 0 || 0.000 | ||
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|} | |} | ||
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Air temperatures decrease as altitude increases up to an elevation of about 123 km, where the coldest atmospheric temperatures are found. A gradual warming begins above 123 km. At an altitude of 194 km there begins a very rapid increase in temperature, suggesting the presence of a [[w:Thermosphere|thermosphere]]. As a matter of fact, the temperature of the upper atmosphere is so high that solar panels will actually overheat and explode rather than simply shearing off as they would in other atmospheres. | Air temperatures decrease as altitude increases up to an elevation of about 123 km, where the coldest atmospheric temperatures are found. A gradual warming begins above 123 km. At an altitude of 194 km there begins a very rapid increase in temperature, suggesting the presence of a [[w:Thermosphere|thermosphere]]. As a matter of fact, the temperature of the upper atmosphere is so high that solar panels will actually overheat and explode rather than simply shearing off as they would in other atmospheres. | ||
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Air temperatures vary with latitude and time of day. At the datum level (elevation = 0) the temperature is a globally constant −73 °C. As the altitude increases, latitudinal and diurnal temperature variations are observed, becoming more pronounced with increasing altitude. At an altitude of 123.45 km, temperatures at the equator vary between a nighttime low of −129 °C and a daytime high of −122 °C. At this same altitude over the poles, the temperature varies between −185 °C and −181 °C. Since Jool has no axial tilt, there are no seasonal temperature variations. | Air temperatures vary with latitude and time of day. At the datum level (elevation = 0) the temperature is a globally constant −73 °C. As the altitude increases, latitudinal and diurnal temperature variations are observed, becoming more pronounced with increasing altitude. At an altitude of 123.45 km, temperatures at the equator vary between a nighttime low of −129 °C and a daytime high of −122 °C. At this same altitude over the poles, the temperature varies between −185 °C and −181 °C. Since Jool has no axial tilt, there are no seasonal temperature variations. | ||
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=== Atmospheric flight === | === Atmospheric flight === | ||
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Since version [[1.0.5]], Jool's atmosphere is well suited for [[aerobraking|aerocapture]] from a high-speed interplanetary intercept. The [[periapsis]] altitude required for a successful aerocapture depends on the spacecraft's drag characteristics, its approach velocity, and the desired apoapsis of the resulting orbit. The most effective periapsis for aerocapture is best determined experimentally; however, for a Hohmann transfer originating from [[Kerbin]], it is found that the median value is about 155 km. A [[Heat shield]] is required to prevent destructive [[overheating]]. | Since version [[1.0.5]], Jool's atmosphere is well suited for [[aerobraking|aerocapture]] from a high-speed interplanetary intercept. The [[periapsis]] altitude required for a successful aerocapture depends on the spacecraft's drag characteristics, its approach velocity, and the desired apoapsis of the resulting orbit. The most effective periapsis for aerocapture is best determined experimentally; however, for a Hohmann transfer originating from [[Kerbin]], it is found that the median value is about 155 km. A [[Heat shield]] is required to prevent destructive [[overheating]]. | ||
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[[Parachute]]s work very effectively in Jool's dense atmosphere. However, even without parachutes, a craft can reach a relatively low speed, depending on the shape of the ship, as well as its mass. | [[Parachute]]s work very effectively in Jool's dense atmosphere. However, even without parachutes, a craft can reach a relatively low speed, depending on the shape of the ship, as well as its mass. | ||
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Jool has no solid surface to land on; descending spacecraft will explode when they reach the altitude of -250 m. The message "... collided with Cloud" will be displayed in the mission summary. The game may glitch out and corrupt the save. Prior to version 0.23, it was possible to land on a solid surface, though spacecraft were inevitably and invariably devoured by the [[Kraken]]. | Jool has no solid surface to land on; descending spacecraft will explode when they reach the altitude of -250 m. The message "... collided with Cloud" will be displayed in the mission summary. The game may glitch out and corrupt the save. Prior to version 0.23, it was possible to land on a solid surface, though spacecraft were inevitably and invariably devoured by the [[Kraken]]. | ||
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If a [[kerbonaut]] is put on [[EVA]], they will not be destroyed immediately, making one-way sacrificial "landings" possible. However this [[Kerbal]] will definitely die, and other glitches may occur, such as the Hell Kraken. | If a [[kerbonaut]] is put on [[EVA]], they will not be destroyed immediately, making one-way sacrificial "landings" possible. However this [[Kerbal]] will definitely die, and other glitches may occur, such as the Hell Kraken. | ||
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== Reference frames == | == Reference frames == | ||
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{{:Jool/RefFrame}} | {{:Jool/RefFrame}} | ||
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== Natural satellites == | == Natural satellites == | ||
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{| | {| | ||
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[[File:Jool System.png|thumb|All of Jool's moons]] | [[File:Jool System.png|thumb|All of Jool's moons]] | ||
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Jool has five natural satellites, each with an orbit well-aligned with Jool's orbital plane: | Jool has five natural satellites, each with an orbit well-aligned with Jool's orbital plane: | ||
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* '''[[Laythe]]''', an ocean moon with many sandy islands, is the only moon with an atmosphere. It is the closest to Jool and second largest of its moons. Due to its high orbital speed, it is somewhat challenging to reach. Next to [[Eve]], its size and composition make it the most similar celestial body to [[Kerbin]]. | * '''[[Laythe]]''', an ocean moon with many sandy islands, is the only moon with an atmosphere. It is the closest to Jool and second largest of its moons. Due to its high orbital speed, it is somewhat challenging to reach. Next to [[Eve]], its size and composition make it the most similar celestial body to [[Kerbin]]. | ||
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* '''[[Vall]]''', an ice moon, is the third largest and second closest of Jool's moons. Its orbital path and velocity sit almost exactly between Laythe and Tylo. | * '''[[Vall]]''', an ice moon, is the third largest and second closest of Jool's moons. Its orbital path and velocity sit almost exactly between Laythe and Tylo. | ||
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* '''[[Tylo]]''', a rocky moon, has gravity similar to [[Kerbin]] and terrain similar to Kerbin's [[Mun]]. It has the largest SOI of Jool's moons, making it easy to encounter, but achieving orbit and landing are exceptionally difficult due to its large gravity well and lack of atmosphere. | * '''[[Tylo]]''', a rocky moon, has gravity similar to [[Kerbin]] and terrain similar to Kerbin's [[Mun]]. It has the largest SOI of Jool's moons, making it easy to encounter, but achieving orbit and landing are exceptionally difficult due to its large gravity well and lack of atmosphere. | ||
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* '''[[Bop]]''', a captured asteroid, is the second smallest of Jool's moons. Due to its distant, erratic orbit and low gravity, it is also challenging to reach. | * '''[[Bop]]''', a captured asteroid, is the second smallest of Jool's moons. Due to its distant, erratic orbit and low gravity, it is also challenging to reach. | ||
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* '''[[Pol]]''', named after its resemblance to a grain of pollen, is Jool's smallest and most distant moon. It is yellow and green, and its terrain is rocky and uneven, with tall, spiky mountains. | * '''[[Pol]]''', named after its resemblance to a grain of pollen, is Jool's smallest and most distant moon. It is yellow and green, and its terrain is rocky and uneven, with tall, spiky mountains. | ||
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Laythe, Vall, and Tylo are in what appears to be a [[w:Laplace resonance|Laplace resonance]], with orbital periods of 1:2:4 respectively. Actual lineup is not the same, resulting in what would be a highly unstable resonance if the moons were not on rails. Despite the fact that the moons can easily eclipse both each other and Jool, they do not. | Laythe, Vall, and Tylo are in what appears to be a [[w:Laplace resonance|Laplace resonance]], with orbital periods of 1:2:4 respectively. Actual lineup is not the same, resulting in what would be a highly unstable resonance if the moons were not on rails. Despite the fact that the moons can easily eclipse both each other and Jool, they do not. | ||
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Synchronous Orbits around any of the Joolian moons are impossible, as they all lie outside the Sphere of Influence of the moons, as is common with tidally locked bodies. | Synchronous Orbits around any of the Joolian moons are impossible, as they all lie outside the Sphere of Influence of the moons, as is common with tidally locked bodies. | ||
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|} | |} | ||
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== Gallery == | == Gallery == | ||
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{{See also||{{Images}}}} | {{See also||{{Images}}}} | ||
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<gallery> | <gallery> | ||
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File:Starship on Jool.jpg|A Starship entering Jool's atmosphere. | File:Starship on Jool.jpg|A Starship entering Jool's atmosphere. | ||
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Jool_Descent.png | A probe deep within Jool's atmosphere which is eventually crushed by the extreme pressure. | Jool_Descent.png | A probe deep within Jool's atmosphere which is eventually crushed by the extreme pressure. | ||
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Jool.png | Jool in 0.17. | Jool.png | Jool in 0.17. | ||
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jool_and_moons.jpg | Jool and its moons in 0.17. | jool_and_moons.jpg | Jool and its moons in 0.17. | ||
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Jool low orbit.png | Low orbit over Jool. | Jool low orbit.png | Low orbit over Jool. | ||
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Winged probe around Jool.png | A Probe with winglets to steer. Note that as you descend deeper into the atmosphere, it gets harder to move at all, rendering RCS and winglets useless. | Winged probe around Jool.png | A Probe with winglets to steer. Note that as you descend deeper into the atmosphere, it gets harder to move at all, rendering RCS and winglets useless. | ||
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Jool aerobraking with moons.png | A view of Laythe, Vall, and Tylo during an aerobraking on Jool. | Jool aerobraking with moons.png | A view of Laythe, Vall, and Tylo during an aerobraking on Jool. | ||
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19Aerobrake.jpg | A Probe aerobraking in Jool's atmosphere as of 0.19, With Laythe, Tylo, and Vall in the background. The aerobraking elapsed 15 minutes before the probe was destroyed. | 19Aerobrake.jpg | A Probe aerobraking in Jool's atmosphere as of 0.19, With Laythe, Tylo, and Vall in the background. The aerobraking elapsed 15 minutes before the probe was destroyed. | ||
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Joolstation.png | A small space station orbiting Jool in 0.20. | Joolstation.png | A small space station orbiting Jool in 0.20. | ||
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File:Kerbal X Near Jool.png|A vessel flys near Jool | File:Kerbal X Near Jool.png|A vessel flys near Jool | ||
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</gallery> | </gallery> | ||
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== Trivia == | == Trivia == | ||
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* Despite being the Jupiter analog of KSP, Jool has roughly the same equatorial radius as the real-life planets [[w:Earth|Earth]] and [[w:Venus|Venus]], because of the fact that the whole game had to be shrunk in size for performance. | * Despite being the Jupiter analog of KSP, Jool has roughly the same equatorial radius as the real-life planets [[w:Earth|Earth]] and [[w:Venus|Venus]], because of the fact that the whole game had to be shrunk in size for performance. | ||
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* The sunsets and sunrises on Jool have a purple-ish hue and are roughly the same color as [[Eve]]'s atmosphere, correlating with the fact that Eve's sunset has a greenish tint of which resembles Jool. | * The sunsets and sunrises on Jool have a purple-ish hue and are roughly the same color as [[Eve]]'s atmosphere, correlating with the fact that Eve's sunset has a greenish tint of which resembles Jool. | ||
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* Like Jool's moons, Jupiter's three nearest moons, [[Io]], Europa, and Ganymede, have relative orbital periods of 1:2:4. Unlike Jool's, Jupiters have differing arguments that result in a true Laplace resonance. | * Like Jool's moons, Jupiter's three nearest moons, [[Io]], Europa, and Ganymede, have relative orbital periods of 1:2:4. Unlike Jool's, Jupiters have differing arguments that result in a true Laplace resonance. | ||
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* Interestingly, if you use an N-Body simulation, the Jool system is very unstable and will rapidly collapse into a radically different system. Vall gets thrown out into interplanetary space, as do Pol and Bop, and Laythe and Tylo become closer together. In order to solve this problem, the moons must be broken out of resonance, or Jool's mass must be drastically increased. | * Interestingly, if you use an N-Body simulation, the Jool system is very unstable and will rapidly collapse into a radically different system. Vall gets thrown out into interplanetary space, as do Pol and Bop, and Laythe and Tylo become closer together. In order to solve this problem, the moons must be broken out of resonance, or Jool's mass must be drastically increased. | ||
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* Jool, Laythe and Tylo all have a surface gravity of 7.85 m/s² (≃ 0.8 g) | * Jool, Laythe and Tylo all have a surface gravity of 7.85 m/s² (≃ 0.8 g) | ||
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* The green gas which composes Jool could be chlorine. | * The green gas which composes Jool could be chlorine. | ||
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* Despite not having a surface, the game files that contain what the Kerbals say in the different reports/observations (ScienceDefs.cfg) also contains some reports while landed on the surface of Jool. | * Despite not having a surface, the game files that contain what the Kerbals say in the different reports/observations (ScienceDefs.cfg) also contains some reports while landed on the surface of Jool. | ||
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{{SpoilerBox | {{SpoilerBox | ||
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|description=Jool surface report/observations | |description=Jool surface report/observations | ||
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|content=*'''EVA Report:''' You're not sure how you even landed on the surface of a gas giant. But it's probably best not to think about it for too long.. | |content=*'''EVA Report:''' You're not sure how you even landed on the surface of a gas giant. But it's probably best not to think about it for too long.. | ||
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*'''Materials Study:''' You're not sure where the container stops and the samples start anymore... | *'''Materials Study:''' You're not sure where the container stops and the samples start anymore... | ||
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*'''Atmospheric Pressure Scan:''' Either the pressure is really high, or the instrument just melted. It's hard to tell what happened first. | *'''Atmospheric Pressure Scan:''' Either the pressure is really high, or the instrument just melted. It's hard to tell what happened first. | ||
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*'''Seismic Scan 1:''' The sensor doesn't even know what to do with itself here. | *'''Seismic Scan 1:''' The sensor doesn't even know what to do with itself here. | ||
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*'''Seismic Scan 2:''' The sensor has informed you that the warranty has just been voided. No refunds. | *'''Seismic Scan 2:''' The sensor has informed you that the warranty has just been voided. No refunds. | ||
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*'''Gravity Scan:''' The instrument has been crushed by the massive gravitational forces. Science! | *'''Gravity Scan:''' The instrument has been crushed by the massive gravitational forces. Science! | ||
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*'''Atmosphere Analysis:''' The instrument has mostly compressed into an unrecognizable mass of metal. | *'''Atmosphere Analysis:''' The instrument has mostly compressed into an unrecognizable mass of metal. | ||
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}} | }} | ||
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* Jool is the only planetary body that cannot be "destroyed" by a planet-busting glitch. | * Jool is the only planetary body that cannot be "destroyed" by a planet-busting glitch. | ||
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* According to a post by former KSP developer NovaSilisko <ref name="Nova October 2015">[http://forum.kerbalspaceprogram.com/index.php?/topic/123271-if-you-could-redesignimprove-the-kerbol-system-what-would-you-do/&do=findComment&comment=2235122 Post in the forum] by NovaSilisko</ref>, he regrets making Jool intensely green and speculates that the green color might be algae. | * According to a post by former KSP developer NovaSilisko <ref name="Nova October 2015">[http://forum.kerbalspaceprogram.com/index.php?/topic/123271-if-you-could-redesignimprove-the-kerbol-system-what-would-you-do/&do=findComment&comment=2235122 Post in the forum] by NovaSilisko</ref>, he regrets making Jool intensely green and speculates that the green color might be algae. | ||
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* Jool is the only completely manually colored planet (i.e. it uses a color map instead of procedural height-based coloration) in the stock solar system. This is because it has no terrain, and thus no procedural noise can color it, and it only exists as a ScaledSpace mesh. Mun and Tylo are, however, *mostly* manually colored. | * Jool is the only completely manually colored planet (i.e. it uses a color map instead of procedural height-based coloration) in the stock solar system. This is because it has no terrain, and thus no procedural noise can color it, and it only exists as a ScaledSpace mesh. Mun and Tylo are, however, *mostly* manually colored. | ||
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== Notes == | == Notes == | ||
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<references /> | <references /> | ||
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== Changes == | == Changes == | ||
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;[[1.10]] | ;[[1.10]] | ||
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* New animated shader and high resolution textures. | * New animated shader and high resolution textures. | ||
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;[[1.2]] | ;[[1.2]] | ||
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* Adjusted datum pressure so crushing pressures are achieved faster. | * Adjusted datum pressure so crushing pressures are achieved faster. | ||
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;[[1.0]] | ;[[1.0]] | ||
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* New atmosphere model, beginning at 200 km instead of 138 km altitude. | * New atmosphere model, beginning at 200 km instead of 138 km altitude. | ||
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;[[0.18]] | ;[[0.18]] | ||
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* Added a new, more distant moon named Pol. | * Added a new, more distant moon named Pol. | ||
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;[[0.17]] | ;[[0.17]] | ||
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* Initial Release | * Initial Release | ||
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{{Celestial Bodies}} | {{Celestial Bodies}} | ||
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[[Category:Celestials]] | [[Category:Celestials]] | ||
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[[Category:Planets]] | [[Category:Planets]] | ||
Revision as of 22:41, 17 November 2021
| Jool | ||
 | ||
| Jool as seen from orbit. | ||
| Planet of Kerbol | ||
| Orbital Characteristics | ||
| Semi-major axis | 68 773 560 320 m [Note 1] | |
| Apoapsis | 72 212 238 387 m [Note 1] | |
| Periapsis | 65 334 882 253 m [Note 1] | |
| Orbital eccentricity | 0.05 | |
| Orbital inclination | 1.304 ° | |
| Argument of periapsis | 0 ° | |
| Longitude of the ascending node | 52 ° | |
| Mean anomaly | 0.1 rad (at 0s UT) | |
| Sidereal orbital period | 104 661 432 s | |
| 4 845 d 2 h 37 m 12.1 s | ||
| Synodic orbital period | 10 090 901.7 s | |
| Orbital velocity | 3 927 - 4 341 m/s | |
| Physical Characteristics | ||
| Equatorial radius | 6 000 000 m | |
| Equatorial circumference | 37 699 112 m | |
| Surface area | 4.5238934×1014 m2 | |
| Mass | 4.2332127×1024 kg | |
| Standard gravitational parameter | 2.8252800×1014 m3/s2 | |
| Density | 4 678.7273 kg/m3 | |
| Surface gravity | 7.85 m/s2 (0.8 g) | |
| Escape velocity | 9 704.43 m/s | |
| Sidereal rotation period | 36 000.000 s | |
| 1 d 4 h 0 m 0 s | ||
| Solar day | 36 012.387 s | |
| 1 d 4 h 0 m 12.4 s | ||
| Sidereal rotational velocity | 1 047.2 m/s | |
| Synchronous orbit | 15 010.46 km | |
| Sphere of influence | 2.4559852×109 m [Note 1] | |
| Atmospheric Characteristics | ||
| Atmosphere present | Yes | |
| Atmospheric pressure | 1 519.88 kPa | |
| 15 atm | ||
| Atmospheric height | 200 000 m | |
| 1.5×10-5 atm | ||
| Temperaturemin | -153.14 °C 120.01 K | |
| Temperaturemax | -48.08 °C 225.07 K | |
| Oxygen present | No | |
| Scientific multiplier | ||
| Surface | N/A | |
| Splashed | N/A | |
| Lower atmosphere | 12 | |
| Upper atmosphere | 9 | |
| Near space | 7 | |
| Outer space | 6 | |
| Recovery | 6 | |
|
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Jool is a gas giant and the sixth planet of the Kerbol star system. It is the Jupiter analog for Kerbal Space Program. Aside from Kerbol, Jool has the largest diameter and greatest mass of all celestial bodies. Its extremely high gravity makes orbital maneuvers unpleasantly expensive. While its distance from Kerbin makes it difficult to reach, it is one of the most appealing targets for missions due to its large and complex system of five moons: Laythe, Vall, Tylo, Bop, and Pol. It was possible to land and plant flags on Jool[1] before v0.23. In versions following 0.23, the craft won't stop at an altitude of -100 m, instead it will continue descending until it gets to -250 m. At this point, anything that hits this altitude at any speed will be completely destroyed. Jool has animated eddies and vortices in high quality.
Contents
In-game description
| “ | Jool is particularly known for being a rather large, predominantly green planet. Kerbalkind has longed to visit it since it was first spotted in the sky. Philosophers reason that the swirling green planet must be a really nice place to visit, on account of its wholesome coloration.
|
” |
Atmosphere
Jool has an extremely dense, cold atmosphere with a mass of approximately 8.8×1019 kilograms (about one ten-millionth that of Jupiter), a datum level pressure of 5066.25 kilopascals (50 atmospheres), and a depth of 200,000 meters. Compared to the atmosphere of Kerbin, Jool's atmosphere has 1875 times the mass, 50 times the surface pressure, and nearly 3 times the depth. At an altitude of 91,554 m on Jool, the atmospheric pressure is the same as at sea level on Kerbin (1 atm).
The average molecular weight of Jool air is 2.2 g/mol, and its adiabatic index is 1.43. Although the composition of Jool's atmosphere is unknown, these values suggest that it consists mostly of hydrogen and helium. The molar mass of Jool's atmosphere is comparable to the real life planet Jupiter. Because of the low molar weight, Jool air at the datum level is only about 2 times as dense as Kerbin air at sea level.
Like all other atmospheres in the game, Jool's atmosphere fades exponentially as altitude increases. The scale height varies with altitude, which is a change from pre-1.0 versions of the game. The pressure-altitude profile is globally constant and independent of temperature. The following table gives the atmospheric pressure at various altitudes above the datum level.
| Altitude (m) | Pressure (Pa) | Pressure (atm) |
|---|---|---|
| 0 | 5 066 250 | 50.000 |
| 10 000 | 1 519 875 | 15.000 |
| 20 000 | 772 776 | 7.627 |
| 30 000 | 613 670 | 6.056 |
| 40 000 | 482 628 | 4.763 |
| 50 000 | 373 138 | 3.683 |
| 60 000 | 283 031 | 2.793 |
| 70 000 | 210 136 | 2.074 |
| 80 000 | 152 282 | 1.503 |
| 90 000 | 107 299 | 1.059 |
| 100 000 | 73 016 | 0.721 |
| 110 000 | 47 263 | 0.466 |
| 120 000 | 27 869 | 0.275 |
| 130 000 | 13 529 | 0.134 |
| 140 000 | 5 319 | 0.052 |
| 150 000 | 2 000 | 0.020 |
| 160 000 | 734.7 | 0.007 |
| 170 000 | 100.0 | 0.001 |
| 180 000 | 29.57 | 0.000 |
| 190 000 | 3.675 | 0.000 |
| 200 000 | 0 | 0.000 |
Air temperatures decrease as altitude increases up to an elevation of about 123 km, where the coldest atmospheric temperatures are found. A gradual warming begins above 123 km. At an altitude of 194 km there begins a very rapid increase in temperature, suggesting the presence of a thermosphere. As a matter of fact, the temperature of the upper atmosphere is so high that solar panels will actually overheat and explode rather than simply shearing off as they would in other atmospheres.
Air temperatures vary with latitude and time of day. At the datum level (elevation = 0) the temperature is a globally constant −73 °C. As the altitude increases, latitudinal and diurnal temperature variations are observed, becoming more pronounced with increasing altitude. At an altitude of 123.45 km, temperatures at the equator vary between a nighttime low of −129 °C and a daytime high of −122 °C. At this same altitude over the poles, the temperature varies between −185 °C and −181 °C. Since Jool has no axial tilt, there are no seasonal temperature variations.
Atmospheric flight
Since version 1.0.5, Jool's atmosphere is well suited for aerocapture from a high-speed interplanetary intercept. The periapsis altitude required for a successful aerocapture depends on the spacecraft's drag characteristics, its approach velocity, and the desired apoapsis of the resulting orbit. The most effective periapsis for aerocapture is best determined experimentally; however, for a Hohmann transfer originating from Kerbin, it is found that the median value is about 155 km. A Heat shield is required to prevent destructive overheating.
Parachutes work very effectively in Jool's dense atmosphere. However, even without parachutes, a craft can reach a relatively low speed, depending on the shape of the ship, as well as its mass.
Jool has no solid surface to land on; descending spacecraft will explode when they reach the altitude of -250 m. The message "... collided with Cloud" will be displayed in the mission summary. The game may glitch out and corrupt the save. Prior to version 0.23, it was possible to land on a solid surface, though spacecraft were inevitably and invariably devoured by the Kraken.
If a kerbonaut is put on EVA, they will not be destroyed immediately, making one-way sacrificial "landings" possible. However this Kerbal will definitely die, and other glitches may occur, such as the Hell Kraken.
Reference frames
| Time warp | Minimum Altitude |
|---|---|
| 1× | Any |
| 5× | 200 000 m (above the atmosphere) |
| 10× | 200 000 m (above the atmosphere) |
| 50× | 200 000 m (above the atmosphere) |
| 100× | 200 000 m (above the atmosphere) |
| 1 000× | 300 000 m |
| 10 000× | 600 000 m |
| 100 000× | 1 200 000 m |
Natural satellites
|
Jool has five natural satellites, each with an orbit well-aligned with Jool's orbital plane:
Laythe, Vall, and Tylo are in what appears to be a Laplace resonance, with orbital periods of 1:2:4 respectively. Actual lineup is not the same, resulting in what would be a highly unstable resonance if the moons were not on rails. Despite the fact that the moons can easily eclipse both each other and Jool, they do not. Synchronous Orbits around any of the Joolian moons are impossible, as they all lie outside the Sphere of Influence of the moons, as is common with tidally locked bodies. |
Gallery
- → See also: Images of Jool
A Starship entering Jool's atmosphere.
A probe deep within Jool's atmosphere which is eventually crushed by the extreme pressure.
Jool in 0.17.
Jool and its moons in 0.17.
Low orbit over Jool.
A Probe with winglets to steer. Note that as you descend deeper into the atmosphere, it gets harder to move at all, rendering RCS and winglets useless.
A view of Laythe, Vall, and Tylo during an aerobraking on Jool.
A Probe aerobraking in Jool's atmosphere as of 0.19, With Laythe, Tylo, and Vall in the background. The aerobraking elapsed 15 minutes before the probe was destroyed.
A small space station orbiting Jool in 0.20.
A vessel flys near Jool
Trivia
- Despite being the Jupiter analog of KSP, Jool has roughly the same equatorial radius as the real-life planets Earth and Venus, because of the fact that the whole game had to be shrunk in size for performance.
- The sunsets and sunrises on Jool have a purple-ish hue and are roughly the same color as Eve's atmosphere, correlating with the fact that Eve's sunset has a greenish tint of which resembles Jool.
- Like Jool's moons, Jupiter's three nearest moons, Io, Europa, and Ganymede, have relative orbital periods of 1:2:4. Unlike Jool's, Jupiters have differing arguments that result in a true Laplace resonance.
- Interestingly, if you use an N-Body simulation, the Jool system is very unstable and will rapidly collapse into a radically different system. Vall gets thrown out into interplanetary space, as do Pol and Bop, and Laythe and Tylo become closer together. In order to solve this problem, the moons must be broken out of resonance, or Jool's mass must be drastically increased.
- Jool, Laythe and Tylo all have a surface gravity of 7.85 m/s² (≃ 0.8 g)
- The green gas which composes Jool could be chlorine.
- Despite not having a surface, the game files that contain what the Kerbals say in the different reports/observations (ScienceDefs.cfg) also contains some reports while landed on the surface of Jool.
Spoiler: Jool surface report/observations
- EVA Report: You're not sure how you even landed on the surface of a gas giant. But it's probably best not to think about it for too long..
- Materials Study: You're not sure where the container stops and the samples start anymore...
- Atmospheric Pressure Scan: Either the pressure is really high, or the instrument just melted. It's hard to tell what happened first.
- Seismic Scan 1: The sensor doesn't even know what to do with itself here.
- Seismic Scan 2: The sensor has informed you that the warranty has just been voided. No refunds.
- Gravity Scan: The instrument has been crushed by the massive gravitational forces. Science!
- Atmosphere Analysis: The instrument has mostly compressed into an unrecognizable mass of metal.
- Jool is the only planetary body that cannot be "destroyed" by a planet-busting glitch.
- According to a post by former KSP developer NovaSilisko [2], he regrets making Jool intensely green and speculates that the green color might be algae.
- Jool is the only completely manually colored planet (i.e. it uses a color map instead of procedural height-based coloration) in the stock solar system. This is because it has no terrain, and thus no procedural noise can color it, and it only exists as a ScaledSpace mesh. Mun and Tylo are, however, *mostly* manually colored.
Notes
- ↑ “Kerbal Space Program: Planting a Flag on Jool” by Dahud Lefthanded in version 0.20
- ↑ Post in the forum by NovaSilisko
Changes
- New animated shader and high resolution textures.
- Adjusted datum pressure so crushing pressures are achieved faster.
- New atmosphere model, beginning at 200 km instead of 138 km altitude.
- Added a new, more distant moon named Pol.
- Initial Release
