ORICHALCUM UNIVERSE Sidebar: LAL-ports...

[Johnny1A.2]

LALports...

A Launch And Landing port (LALport), in my Orichalcum Universe, is a means of launching and landing spacecraft used by societies that have developed tractor-beam and pressor-beam technologies. On Earth in the early 22nd Century, there are several LALports, spread around the world and used for launching both manned and unmanned vehicles, and bringing in spacecraft as well. The Empire maintains three, the United States two, and the Chinese Union maintains one with another under construction as of 2120. The Arabian Caliphate has one, the Crowned Republic of Australia maintains one, Argentina maintains one, and two others are under construction.

Though each such facility is unique in detail, all are broadly similar in overall function and design, so a description of one will do for all. The United States LALport in the State of Panama will do as an exemplar.

Constructed in the mountains of the Isthmus of Panama, Port Armstrong from the air resembles a one and a half kilometer wide circular gantry, spread out over an area of leveled solid rock. At the center of the structure is a raised circular structure about one hundred and fifty meters in diameter. The outer disk rises about twenty meters above the ground level, the inner disk another ten meters above the main structure.

Spaced around the rim of the are six tower-like structures, again resembling tall pyramidal gantries, rising about three hundred meters above the level of the main disk. Surrounding the entire complex are enormous solar power converters, interspersed into the structure are ramps and elevators for access to the launching platforms.

A typical launch begins with a spacecraft or cargo pod placed on the raised central platform. This inner emitter disk then generates a lift field, a zone or volume of repulsion, that lifts the vehicle directly upward. This inner field lifts the vessel several kilometers into the air, at which point the relatively short ranged inner field switches over to the more diffuse but longer-ranged field generated by the outer disk.

The field generated by the outer disk is not light, but the emitter grid can be compared to a lens. The field emitted by the outer disk is diffuse at source, but concentrated toward a focal point at distance, in a way analogous to a magnifying glass concentrating light. The focal point, of course, is maintained on the spacecraft. The towers around the perimeter direct the field and help make the focal point laterally steerable. This, in turn, permits the focused field to not only lift the ship, but to accelerate it to orbital velocity and direct it into a chosen trajectory to reach a desired orbital path, or alternatively, to accelerate a ship to escape velocity along a desired vector.

The same process can be used to decelerate a spacecraft and lower it safely to the surface. The focused field can easily reach to low orbital altitudes with sufficient force to brake a ship and bring it safely down. At higher altitudes the force is much reduced, but even a ship in geosynchronous orbit can be landed by this process, albeit by applying the grid repeatedly to lower the orbital path. Much beyond geosynchronous altitude, however, the field is too weak to be of practical use.

The nature of this technology has several advantages for launch and retrieval. One is that all the acceleration and deceleration is provided by the ground facility, enabling a ship to reserve all of its delta-V for later use, or a ship that has exhausted its delta-V to land safely. It can also be used to launch and retrieve payloads with no on-board propulsion at all.

Also, the nature of the force involved is that it affects the entire mass within the volume of effect. It does not simply press into the surface of the payload, but like gravity (it is not gravity, but behaves like gravity in some ways), affects every atom within its volume of effect more or less equally. This means that a payload can be launched, or retrieved, using very high accelerations, without any stress or strain on the payload. Standard launch protocol uses an acceleration of 98 meters/sec/sec, but higher accelerations are possible in emergency situations. Landings tend to be gentler, but the uniform effects apply either way.

Note that this requires that the focal point of the field stay properly focused on the payload, and balanced by the perimeter towers. If the field is improperly focused, the ship and its contents will feel acceleration stresses, which can range from uncomfortable to fatal, depending on the imbalance.

Also note that if the focus is lost entirely, for whatever reason, the result will depend on how high the contents are and how fast and on what vector they are moving. If focus is lost too low, the ship will crash, unless it can make use of onboard propulsion to save itself. If it is lost too high, it might enter orbit, but the wrong orbit.

Armstrong Base has redundancy designed in, it could theoretically lose two of the towers during a launch or landing operation without undue problems. Loss of a third, however, could prove problematic, and losing four would mean near-certainty of catastrophic failure.

To be continued...

[Johnny1A.2]

LALports continued...

LALport technology offers enormous advantages over older forms of launch and landing. Amstrong Base (and the similar facilities elsewhere) is fully capable of lifting anything that will fit onto its central launch platform and masses under one thousand metric tons into LEO, GEO, or escape velocity, with no onboard propulsion necessary. More massive loads can be orbited, though with greater cost and difficulty, as long as they will fit volume-wise onto the central launch platform and into the field-effect of the first-stage boost system. The more massive the load, naturally, the longer it takes to launch and the more expensive the launch, and the most massive possible payloads are limited to certain orbits absent the use of on-board propulsion.

Even so, a one thousand ton spacecraft, able to reserve its entire delta-V for maneuvers on the far end of the voyage, is able to go almost anywhere in the Solar System if launched and retrieved by a LALport. With a reasonable mass ratio of from two to four, and a nuclear light-bulb drive, interplanetary voyages can be performed in quite reasonable times, and a LALport makes good mass ratios relatively easy to attain. Longer journeys can be done in reasonable times by use of ion drives or similar, which also gain enormous benefits from use of LALport technology.

Armstrong Base, like the similar facilities elsewhere, is solidly anchored to the ground beneath, both by conventional frictional forces and force-fields related to the same technology used for launch and landing. Enormous anchoring masses are sunk deep into the solid rock below Armstrong Base, which by themselves provide enormous stability. A diffuse version of the same force-fields that launch the payloads grip the rock below the base to a much greater depth, anchoring the facility even more soundly to petatons of mass.

Note that this is why LALport technology does not work well in open space. Without the anchoring mass, every ship or cargo pod launched or retrieved would change the orbit of the complex itself, in accordance with the rocket equation. Either the inflow and outflow of mass would have to be delicately balanced, or constant station-keeping thrust of some sort would be necessary. Efficiency would also drop, because much of the energy used in the process would be 'wasted' accelerating or decelerating the complex itself, rather than the payload proper, and the problem with get worse with larger payloads. On the surface, in contrast, anchorage is straightforward.

The same orbital mechanics apply to LALports that do to any other launch facility. That is, the closet to the equator the launch site is positioned, the easier it is to launch payloads into east-directed orbit, and the fewer orbital plane changes tend to be necessary. Conversely, closer to the equator is worse for westward launch, but the large majority of all space launches are into an eastward orbit.

Also, the force-field has to stay fairly well above the horizon line to work. If the force-field 'grounds' into the horizon, suddenly the tractor-pressor system is trying to accelerate billions of tons instead of a few hundred. Safety systems will cut off the power if this happens, because otherwise the generators and emitter grid become the weakest point in the system. A 'grounded' LAL-field can wreak havoc with the system in seconds. Even too much atmosphere in the beam-path can begin to cause problems, though the tendency of gas to flow out of the beam reduces this issue considerably.

Payloads have to reach their target velocity with the beam still above the horizon, which limits how long the system has to bring this about.

Armstrong Base is in the State of Panama, which is as close to the equator as the United States could manage while staying in American territory. It is substantially south of the older launch facilities at Cape Kennedy, but problematic in that due east of the Panama location likes Imperial territory rather than open ocean. Launching toward eastward equatorial orbit from the site in northern Panama takes a payload across the Imperial Provinces of Venezuela and Columbia, depending on the exact route used.

For this reason, at Armstrong Base the usual protocol is to boost for altitude first, pushing the payload to a high altitude before imparting much lateral acceleration. This has the benefit of keeping the field well above the horizon line, reducing safety and legal issues during overflight over South America, and also reducing the risk of deliberate interference. [1]

LALports can be used to interfere with each other. There are two broad ways this can be done, with many detailed variations. The first is to simply use the field from one facility to interfere with another. The simplest form of this is to disrupt the focal point while the payload is low enough to either crash or burn up. With greater skill, it is possible to 'snatch' a payload from another facility entirely, gaining control of its path and even forcing it down at the other port.

Alternatively, a very diffuse field can be used to 'jam' the efforts of the other port entirely, making it impossible for either to extend coherent effects much beyond the immediate vicinity of the facility. This requires that both facilities be relatively close to each other, of course, but the Imperial launch facility in Brazil is easily close enough to Armstrong Base to for either to engage in such activities against the other.

In practice, of course, this rarely happens outside of wartime. One nation tends to become very irate if another captures its payloads or forces its launch facility to shut down. The latter tactic also paralyzes the attacking facility, and so is engaged in with reluctance. Most of the time, Armstrong Base and the Imperial equivalent near Macapa actually work in support of each other, sometimes lending assistance during emergencies.

(Beam failures do occasionally happen.)

To be continued...


[1] A variety of treaties and customary international rules apply to what sorts of overflight are allowed where and when. A combination of loopholes and informal agreements applies to space launches over rival territories, but it can be tense at times.

[warellis]

How advanced is gravity control for Earth humanity in 2200? How much have they been able to advance on that path?

[Johnny1A.2]

Originally Posted by warellis

How advanced is gravity control for Earth humanity in 2200? How much have they been able to advance on that path?

Well, that has two answers.

The first is, not much. That is, actual control and manipulation of true gravity is not much more manageable in 2120 as it is now. Gravity as such depends on the presence of mass.

But physics has discovered entire new forces that can be manipulated, such as the force-fields used by the LALports. They share some properties with gravity, some with electromagnetism, some with nuclear forces, and have some properties unique to themselves.

The potential for greater and more subtle effects exist, but that's still on the drawing boards and theoretical models as of 2120, except for one small group that has access to more advanced abilities.