A small guide to the basic tasks in Kerbal Space Program, written not so much about the game, but about the basics of cosmodynamics in general and orbital mechanics in particular, also telling some details not included in the game about the operation of spacecraft in reality. Understanding physical laws will prepare you not only for performing planned maneuvers, but also for quick improvisation, which is sometimes necessary in space conditions. But, although the guide is small, there will be a lot of text. It’s worth being mentally prepared for this.
The game interface, walking and space modules like temperature/pressure sensors have little to do with orbital mechanics, they can be easily figured out without straining, and I won’t dwell on this. There will be no formulas in this manual, and everything that is usually described by them will be presented in simple language. This should be enough for all the basic cosmodynamics to be mastered in order to understand what actions we perform in the game and how it works in reality.
I also tried not to throw out pages of terms, but to introduce the necessary concepts when we really need them in practice. Therefore, instead of theory, let’s go straight to the rocket-building hangar.
First flight.
Important points of the ship
The very first thing you will be asked to do is carry out the first launch. For our first flight, it is advisable to know how a rocket flies in general. Any rocket engine throws a certain mass out of the rocket and thus the rocket applies a certain force to this mass, pushing it out. According to Newton’s third law (the law of equality of action and reaction), this mass exerts reciprocal pressure on the rocket, which tends in the direction opposite to the flow of the ejected substance (see. rice.1). This pressure is called traction force.
So, a ship is needed. Any device must be controlled by something or someone, so first of all we pay attention to the module that our astronaut can fit into (in the future, robotic command centers and expanded modules for several crew members will appear).
Now and further I propose to solve any given task from the end, i.e.e. think first about what actions our device will perform last, and then move backwards in chronological order. For example, if we are talking about the first takeoff, then the situation will be like this. Our control module with the astronaut should remain on the surface of the planet. To avoid crashing on the ground, he will need a parachute. And then we need direct engines, and so many so that the parachute can support the total weight of the ship (hereinafter we will use dictionary definitions – mass is the amount of substance, and weight is the force of influence on the support, they should not be confused). For a simple start without any purpose, you can take the cheapest solid fuel engine.
Notice the panel with buttons showing the center of mass (mass), center of lift (aerodynamic) and center of thrust (thrust). They include displaying the corresponding points on the model of our rocket (Fig. 2).
The center of mass is a point that characterizes the movement of the body as a whole. It is also called the point of inertia, since it is relative to this point that we can calculate the inertia of a body when a force is applied. Please note that during the flight of the ship, the center of mass may change due to fuel consumption in the tanks, which will become lighter.
Center of thrust – a point located between the points of exhaustion of forces in such a way as to equalize their total force in one direction (indicated on the point) relative to the entire ship. This point will be most important for us in aerodynamic calculations, since spacecraft rarely use all engines at once, in addition, they are usually centrally symmetrical along the longitudinal axis, which means the point will lie on this axis.
Center of lift – a point located between the surfaces of the wings so as to equalize the total lift of the wings in one direction (indicated on the point) relative to the ship. Again, the center of lift may change as the stages separate. In addition, on vertical take-off vehicles, the wings rarely create lift as such, which is why this parameter is also important mainly for aerodynamics.
If you want the rocket to fly straight without the application of force (and you usually really want this), then the center of mass and the center of thrust must be along the axis along which you will fly, relative to each other (Fig. 3)! Otherwise, somersaults will begin, which usually lead to an unplanned landing. It is also not recommended to place the center of thrust above the center of mass relative to the surface of the planet, since in this case the lower part will begin to sway during flight. When the structure is assembled, you need to distribute the controlled elements in the desired sequence in the step panel. Make sure the engine fires first and then the parachute.
So, the device is ready. At the site you need to initiate the launch, after which the rocket will begin to gain altitude and speed. Having exhausted the resource, it will fall to the ground. If at this moment you allow the rocket to simply fly nose down for a long time, then you will not be able to launch the parachute, since the air resistance will not be enough to decelerate, and soon the speed will be reached at which the parachute will be torn off by the same air resistance. Therefore, make sure that when falling you have time to open the parachute where there is already enough air to start braking, but the rocket has not yet reached a high speed towards the ground. When the parachute is opened, all you have to do is watch the landing. So, your cosmonautics reached 1633, when a manned rocket was successfully launched in Istanbul for the first time. Yes, yes, already in the 17th century, the rocket was approximately the same design – a cone containing a pilot (his name was Lagari Khasan-chelebi), solid fuel engines running on stabilized gunpowder, and an improvised parachute-wings. In fact, over the next three centuries, parachutes underwent much more changes than rockets.
We leave the atmosphere and return.
Let’s talk about fuel, engines and stabilization
After earning some science points on flights and discovering some new parts, you will be given the task of going beyond the atmosphere. To do this you will need slightly higher power accelerators and some knowledge about them. Liquid fuel will be our main means of conducting space maneuvers. The engine consuming it (Fig.4), will require for operation directly the liquid fuel itself and the oxidizer, which must be located in a tank connected to the engine by structures capable of conducting fuel. Please note that there are tanks designed for atmospheric flight, they do not contain oxidizer and will not support engines outside the atmosphere.
With fuel everything is more or less clear. It can be kerosene, hydrogen, hydrazine and several other flammable compounds, depending on the required combustion temperature and the available volume.
What is hidden behind the simple word “oxidizer”? Of course, from the word itself it is clear that it is mainly oxygen. In our everyday life, it is precisely this that acts as a reagent for most oxidations, since it is located directly in the air. Liquid oxygen is used in space flights. However, this is not the only option. For example, the oxidizing agent can be nitrogen tetroxide, which is not flammable and boils at +21 degrees Celsius, which means it is much easier to store and transport. Among less obvious examples, fluorine is used as an oxidizer, which is extremely explosive and toxic, capable of burning almost any substance, including water, but allows for maximum compaction of the fuel and achievement of the highest combustion temperatures.
The rocket industry has very stringent fuel requirements.
First of all, it is necessary to create the densest possible fuel, saving volume, and priority is given to substances that can be well compressed.
Next comes the problem of storage and transportation, and we pay attention to the boiling point of the fuel components. Many of them boil even at such low temperatures, which do not exist in nature, which means that it is simply impossible to transport or store them, just as it is impossible to carry out long flights, not to mention the fact that ice begins to form on the rocket even at the launch pad, which can lead to an accident.
The chemical aggressiveness of fuel oxidizers is also important for us, because when using such substances the reaction must proceed in a controlled manner, and even a greasy fingerprint on the wall of the tank can lead to the ignition of fat in an acidic environment, causing a fire in which not only the fuel will burn, but also the metal itself from which the rocket is made.
It’s fortunate that the KSP developers do not force us to choose components for the fuel of our rockets – it always works flawlessly and is stored indefinitely, which means that liquid fuel accelerators have practically no disadvantages for us.
Solid fuel boosters (Fig.5) differ in that they cannot be controlled. You can reduce the volume of loaded fuel or the maximum thrust at the design stage, but after launch it will accelerate our device at full speed until it exhausts its entire resource, and then goes out forever. Such accelerators are good because they are cheap, lightweight and do not require additional structural elements (and in reality, also because they have high reliability, since in the absence of acceleration the ship is in a state of free fall, and the fuel itself is in the same state, which means that when igniting a liquid fuel engine there is a risk that it will dangle out of contact with the ignition, and therefore will not be supplied in a timely manner; this situation is usually prevented by the fact that when starting a liquid fuel engine the ship is given a slight acceleration by other means, but this method is not implemented in the game and the engines always operate normally, greatly delighting the astronauts). The principle of operation of such an accelerator is much simpler – the fuse ignites the fuel, which already contains an oxidizer, and during combustion the mixture exits through the nozzle. A variety of fuels can be used. Lagari flew on black powder, modelers use the so-called “caramel” – potassium nitrate and sugar. In modern rocket engines, nitrate and perchlorate are most often used as oxidizers, but the fuel can be very diverse. For example, ordinary aluminum often plays its role. Or rubber.
It’s worth knowing that the most obvious method of launching a rocket further away – hanging boosters wherever you can – doesn’t always work, not to mention the increased cost of your rocket as a result of this approach. The fact is that the initiated engines will be forced to accelerate the entire total mass of the device, including the mass of the engines that have not yet been initiated. Therefore, the efficiency of the lower stages will drop depending on the mass transferred, up to complete uselessness. The launch of all accelerators at the same time will, firstly, be structurally difficult, since the flame falling directly on parts of the rocket will heat them up, which should be avoided if possible, and secondly, a situation is possible in which the speed of passage of the atmosphere will be so high that heating by friction with the air will destroy some parts of the rocket.
In order not to drag a useless load, we have decouplers at our disposal. These are the parts of the rocket that separate the stages. In the connected state, they impart the rigidity of the body to the parts of the device, and when activated, they throw them with a slight impulse in different directions. Be careful not to fire the squibs at the same time as the motors they separate. Most of the devices that you will design will consist of several stages, as Tsiolkovsky proposed in his time (see. rice. 6).
Of course, in reality, a large number of stages means a large number of elements that are disposable and cannot be tested before launch, which means less reliability of the entire device as a whole, but in the game we are not in danger of breakdowns, and we can create dozens of stages, there would be no point. Please note that for a successful take-off, a jet acceleration is required that exceeds the acceleration of gravity, which means that the accelerator must carry a load that weighs less the more the device overcomes gravity (which is felt more strongly when approaching an object in whose gravitational field we are located).
It is also worth considering that the more our acceleration exceeds gravity, the less energy loss we will incur due to the fact that gravity will act for less time. But don’t get carried away, it threatens to overheat.
So, several stages with engines will help you reach the desired height. If you notice unnecessary somersaults and involuntary changes in trajectory during takeoff, pay attention to the SAS stabilization system, the principle of which was invented by Tsiolkovsky – heavy flywheel disks are installed on three axes, which can rotate around their axis and strive to maintain their rotational inertia, thus counteracting external effects (Fig.7). In later versions of such systems, the disks are replaced by one spherical flywheel, which can rotate along three axes at once. If necessary, the flywheel can spin stronger or weaker, imparting resistance to the ship. Such a system allows you to correct or stabilize the course by rotating the part on which it is installed (by default this is the command compartment) around the center of mass. This requires an electrical charge, which is stored in batteries or the same command compartment or is provided by the operation of the engine. The greater the mass of the device, the weaker the effect of SAS will be felt, which means that it is most difficult to compensate for the deviation during takeoff.
If even when stabilization is turned on, the rocket deviates strongly, then it can be stabilized by adding flaps. Place them centrally symmetrically and as close to the tail of the rocket as possible to increase maneuvering efficiency (as in the V-2 photo). If this does not help, then you can try to slightly rotate the flaps relative to the air flow, then during takeoff the device will rotate quite quickly around its axis, thus maintaining stability. Don’t worry about the astronauts, they’re normal.
So, the atmosphere remained down there, https://betitoncasino.co.uk/mobile-app/ and we achieved the success of astronautics in 1944, when the German V-2 rocket went beyond the Earth’s atmosphere.
Around this point, you will be able to consciously achieve the desired speeds at the desired altitude, correctly setting the thrust of the boosters and the amount of fuel for them. This will require a little practice, since the setting must be very precise – sometimes 5% booster fuel means 200 m/s on the desired part of the trajectory. The ability to approximately know the ratio of weight and thrust to achieve heights and speeds will allow you to easily complete equipment test tasks, thus earning money for new parts. You will also be able to carry out tasks to reach certain points on the planet at high altitudes, simply by deflecting the rocket in the desired direction during launch and flight. Please note that in this case you will have to compensate for the rotation of the planet, which means that you cannot unconditionally rely on the trajectories on the map, and you need to fly according to the navigation panel.
Making an airplane.
About axes and again about axes
After some time, tasks will become available to you in various dimensions on the surface or at low altitudes, and it will be very difficult to send a rocket there. So, we need to start creating an airplane.
For aircraft engines, we do not need to have an oxidizer, since there is enough oxygen in the atmosphere, which can be supplied through air intakes, but it is worth remembering that each engine has its own altitude ceiling, when approaching which its thrust will drop due to a lack of oxidizer. We need an airplane engine solely for acceleration relative to the axis of motion, and the lifting force of the wing will pull us upward. The wings in the game act approximately the same and do not differ in profile, so we will not go into details of the formation of the lift force, we will simply note that it arises due to the unevenness of the air flow around the wing (if you are interested in this topic, you can study the Zhukovsky theorem) and that it is directed perpendicular to the surface of the wing (do not try to change the angle of attack, that is, the angle of the wing surface relative to the air flow, in the game, unlike in reality, this is not works, but simply deflects the lift back, which we don’t need).
In the process, we will often control the rotation of the aircraft not relative to the planet, but relative to the center of mass of the aircraft, in order to make the most efficient use of air flows for maneuvering. Rotation around the center of mass is carried out along three axes. Rotation along the longitudinal axis of the aircraft is called roll, along the transverse axis is called pitch, and along the vertical axis is called yaw. Our task is to stabilize the flight of the aircraft so that during level flight it does not deviate from the course along any axis. To do this, it is necessary to ensure the coaxiality of the center of thrust and the center of mass of the device, as before, but it is desirable to completely align the center of mass with the center of lifting force. If we allow these centers to deviate along the longitudinal axis, the aircraft will constantly strive to descend or rise, which requires constant compensation. Theoretically, of course, such deviations can be compensated by moving the center of thrust below or above the longitudinal axis passing through the center of mass. For example, many modern fighters have a lower center of thrust, but the center of mass relative to the center of lift is shifted forward. However, in the game it is much easier for us to artificially combine the centers than to mess around with compensation for deviations.
The plane also needs to have ailerons, elevator and rudder – special planes of the wings and tail that can deviate at a certain angle, redirecting air flows. The ailerons are located at the ends of the wings along the pitch axis and control roll, the elevator is located in the tail along the pitch axis and controls pitch, the rudder is located in the tail parallel to the yaw axis and controls yaw. The game has a simplified rudder control system, so the same devices can have different functionality, for example, if the wings are moved towards the tail, then their ailerons can serve as an elevator, and you do not need to assign buttons somehow. You can even put the wings at an angle, and their ailerons will simultaneously control all axes, albeit less efficiently. However, for ease of perception, I would recommend using the classic layout, even if the appearance or simplicity of the design of the device suffers because of this.
Controlling an airplane is simple, much easier than controlling a rocket. However, there is one point worth clarifying. If you need to change course, don’t use the rudder to do it! Yaw is a means for minimal correction, not for maneuver. It would be much better to roll in the right direction and control the pitch, and then level off.
For takeoff and landing we will use the landing gear. It is always worth considering that the chassis cannot withstand any load. They can be destroyed either by an impact at high speed or by excessive pressure, that is, if you are landing a heavy aircraft, then this must be done very, very smoothly, on all wheels, at minimum speeds and at a minimum angle between the stripes of the wings and the surface. Sometimes there will also be a need to land in a mountainous region where standard landing is very dangerous. Therefore, just in case, I recommend adding several parachutes to the plane, placed around the center of mass so as to descend flat in relation to the ground. And don’t forget that if there is an engineer on board, he will be happy to repack your parachutes, which means you will be able to fly over more points during the flight.
Aircraft designs will change minimally during the game, control principles will change as well, and new details will only give you new speeds, height ceilings and better controls, so that’s probably all you need to know about aviation. Just wait for good details and experiment to your heart’s content. Here, for example,
Reaching orbit.
Endless drop and a couple of steps
The next task will be to enter the planet’s orbit. From now on, when performing a maneuver that you are not sure of, calculate it in advance using the flight planning system (for this you will have to improve the flight control center). The accuracy of maneuvers must be almost perfect, so you should not use powerful engines for maneuvering; it is better to wait a few extra seconds than to waste fuel on correcting mistakes.
So, first of all, let’s talk about what an orbit actually is. All our past flights began on the surface and ended on it, since we were attracted by the planet itself. It seems that the solution is simple – leave the gravitational field of the planet and hang in space for as long as necessary. Unfortunately, this plan is doomed to failure, because the ship is actually affected by the gravitational forces of all the surrounding celestial bodies. If we fly far enough, we will actually leave the planet’s gravitational zone, but we will begin to be inexorably pulled towards the star around which this planet revolves, moreover, we will not be motionless even near the star, since we have the speed relative to it that the planet had. However, there is a way out. If we fly away from the surface and then set the horizontal speed, then when we fall on the planet our ship will miss it and fly around. According to Newton’s first law, the movement of our rocket would be rectilinear if not for gravity, and this gravity pulls us down, but not against the vector of our horizontal movement (Fig.9). This means that we can fall not on the planet, but around it, and fall endlessly, since gravity drags us down as constantly as a given horizontal acceleration, which is not changed by any other forces.
Thus, the movement of a body in orbit is a constant fall and does not require any additional effort. If you put a ship into orbit of a planet, then it can hang there for centuries. However, make sure that there is no atmosphere at any point in the flight (on Kerbin the atmosphere is below 70,000 meters). Otherwise, the ship will begin to slow down due to friction with the air, lose horizontal acceleration, and therefore fall onto the planet.
So, to complete such a task, you will need a powerful push that will bring a sufficient number of accelerators to a given height in order to set the desired horizontal speed at the top point – just turn the rocket ninety degrees (this is much easier to do outside the atmosphere) and give thrust. On the map you will be able to observe how the arc of your trajectory stretches, gradually covering the entire planet.
Here it is worth talking about the fact that the rocket must launch vertically in order to penetrate the dense layers of the atmosphere, where air resistance is high, but later turns into a horizontal state. The smoother this transition is, the more fuel can be saved, since in the case of constant vertical acceleration, the force of gravity acts in the strictly opposite direction of acceleration, which means it is least effectively overcome. When the vehicle begins to fall to the side, the losses become smaller, since the vector of the force application loses less net speed, paying with the angle of ascent (if we add up the vectors of the force of attraction and acceleration of the rocket from the engine, the final vector will be longer, the smaller the angle between the vectors, however, since we need to at least not descend, the best acceleration is along the surface). Since to form an orbit we need a certain inertia, which is a consequence of speed, it will be more advantageous to tilt the rocket’s take-off trajectory during the ascent process, and the sooner air resistance allows this, the better.
When the orbit is stabilized, you need to return back. Do not try to point the device directly towards the ground, this will lead to a narrowing of the orbit too slow to reach the surface! To land a rocket, it’s easier for you to make sure that gravity takes over the horizontal speed, and then the ship will fall not beyond the horizon, but to the surface. Simply turn against the vector of motion, engage thrust, reducing your horizontal speed, and get ready to deploy your parachute. The temperatures after this will be serious, the speeds too, and the easiest thing will be to land only the command compartment itself.
Congratulations, you have reached the level of 1961, in which the first man was put into orbit in the USSR. Of course you’ve heard about him.
First space maneuvers.
A little about Kepler, a lot about the attitude indicator
When our vehicle confidently enters orbit and returns from it, we will be able to carry out missions to launch satellites into specific orbits. Instead of a command unit, we need to install an automatic communication center on the satellite, which will control the ship under our leadership.
In this case, the command module’s SAS system will be disabled for lack of it, and we will also need to install an external flywheel in order to maneuver in space. To maintain control over the satellite, energy is needed, which means it is worth installing solar panels on the ship, making sure that they receive sunlight and are not blocked by other parts of the ship. This is very important because we will often be rotating the ship and we need to be able to replenish energy reserves regardless of direction or be careful to ensure that the panels are facing the sun when drifting in space.
We should also be afraid that some celestial body will block our signal from Kerbin, and our device will become uncontrollable (for example, flying along the equatorial orbit of the moon, it will describe part of the arc in this very state). And finally, if you want the satellite to transmit something, you should put special antennas on it for transmitting scientific data, as well as instruments for reading this data.
Once the design is complete, it’s time to start achieving the desired orbit. But to understand this process we need Kepler’s first law. Kepler himself spoke about the planets and their rotation, but the same laws apply to our humble spacecraft when its engines are turned off. So, slightly paraphrasing the first law, the orbit of rotation of one body around another is an ellipse, at one of the foci of which the body being flown around is located. An ellipse is a circle built around two points, called foci, so that the total distance to the foci at each point is the same (Fig.11).
In this case we will revolve around the planet. The terms of reference clearly indicate the orbit that we must occupy. Since the planet is located at one of the ellipse’s foci, it will in any case lie on the same plane with any such ellipse, which means it will be on the same plane with any possible orbit. It turns out that when we put a satellite into orbit, half the work was already done, because one focus of our orbits automatically coincided. All that remains is to combine the rest. Now we will have to use the attitude indicator (navball). In order not to dwell on it later, let’s deal with its legend right away (Fig.12).
The attitude indicator indicates: Direction (prograde) and return (retrograde). They set the axis of direction of the ship’s movement. Thrust in the direction of movement will increase our speed without changing the vector, return thrust (t.e. against the direction), on the contrary, will reduce the speed. Normal and anti-normal indicate an axis perpendicular to the orbital plane. Normal thrust will increase the inclination of the orbit clockwise, while anti-normal thrust will increase the inclination of the orbit counterclockwise. Inside the orbit (radial in) and outside the orbit (radial out) define the axis going to the center of our orbit. Inward is the direction towards the center, into the radius of the orbit of the orbit. Outward, respectively, outward, from the center. The inward thrust of the orbit will tilt its radius along the rotation; the outward thrust, on the contrary, will tilt it against the rotation. The directions are shown more clearly in Fig. 13.
If we have already planned a maneuver, the attitude indicator shows the direction of the maneuver (maneuver prograde) – a mark showing the direction in which we need to accelerate according to the plan marked in advance on the map. Also, when using this option, it will be shown next to what speed we need to reach and after what time we will reach the point of the planned maneuver.
If we select an arbitrary object in space as a target, markers towards the target (target) and away from the target (antitarget) will also appear, they build an axis between the center of mass of our ship and the center of mass of this object. We will use direct movement to and from the target when the orbits of our ship and the target almost coincide. Craving towards or away from a goal will mean approaching or, accordingly, moving away from the selected object.
So, let’s start combining the orbits. Let’s start with the plane as a whole. Let’s find a straight line in which the planes of our and the desired orbits intersect (as we already know, our planes have a common point in the form of a planet, and such a straight line will pass through it). On the map this line is indicated by a dotted line, and if you calculate the alignment of orbits in reality, then simply look at the orbital planes from the point from which both of them will look like straight lines (i.e.e. from the side, as shown in Fig. 14).
The desired line will pass through the point of their intersection along our view. It crosses the orbit of our ship at two points, which are called ascending and descending and are also marked on the map. Being at any of these points, we need to accelerate along the normal or anti-normal, depending on which of the angles is smaller, until the orbits are in the same plane. After this, we need to combine the direction between the foci of our orbit and the desired one. This is an optional maneuver and can be neglected if the target orbit is almost circular, but if it is very elongated, it will be easier to work with the interfocal direction first. To do this, find two points: the one that is as far as possible from the body around which we are rotating, and the one that is as close as possible. They are called apocenter (apoapsis) and periapsis (periapsis), respectively, and are also marked on the map. The straight line passing through them will be the direction between the foci. Mentally extend it and find the points at which this line intersects the orbit of our ship. While at that point, give thrust in or out of the orbit depending on the position of its radius relative to the radius of the target orbit. Now it remains to adjust the rotation speeds at the current apocenter and periapsis. Once at one of these points, look at the opposite point from the body you are rotating around, the target orbit point. If it is outside your orbit, then give thrust in the direction of movement, if inside, then return thrust and wait until the orbits at this point coincide. Describe a half turn and repeat.
Rescue of non-drowning people and flights without ships.
About meetings in space and a little more about Kepler
Having played enough with changing orbits, you can begin to replenish the team of astronauts. But you won’t hire them when there are volunteers hanging out there in space, ready to pay extra for their salvation? So that’s what we’ll do. Select a rescue mission, we will provide assistance.
We will need free space on the ship for this. You can use special modules for passengers in addition to the regular cabin, then the ship will be a little harder to land, you will need props and additional parachutes, and maybe even a heat shield, which needs to be located in the lower, particularly hot part of the ship. Or you can just make a satellite with an empty cabin on it. First, select the astronaut to be rescued as a target on the map (sometimes we will need to reset the target if we need to maneuver relative to the planet) and enter his orbit as you did before. However, if your rescue shuttle continues to rotate in the same orbit as the one in distress, they will never meet, and if you accelerate, the orbit will simply stretch. What to do?
Kepler’s second law comes in handy here. It states that in equal periods of time, the radius vector connecting the planet/satellite and the body in orbit describes equal areas. Simply put, if we imagine that the segment connecting our ship and the planet divides the orbit into sectors at equal intervals of time, then these sectors will be the same in area. Several important conclusions can be drawn from this. Firstly, it turns out that the larger the area and extent of the orbit, the more time it takes to complete it. Secondly, the closer we are to the object we are flying around, the faster we move. This means that if we increase our speed, then both the orbit and the time it takes to travel will increase (due to the drop in speed from the other edge of the orbit). Let’s desynchronize the shuttle and the person being rescued by increasing the speed relative to the planet (if the shuttle needs to catch up with it, and not vice versa, then the speed needs to be reduced, but be careful not to fall into the atmosphere). So, after a few revolutions the distance between them will decrease. The map will indicate intersection points (intersect) and the distance between our objects at these points. We need to achieve an accuracy at which we converge in less than two kilometers (and preferably within half a kilometer).
As a last resort, remember that if it is not possible to achieve high accuracy, then we can always slightly desynchronize the orbits by maneuvering in or out of orbit, and our planning system will tell you which maneuver will have the shortest distance. This method, however, requires some practice, since in case of a miss you will have to restore the orbits. However, if you find yourself ten or twenty kilometers from each other, then adjusting this distance is quite simple. When the intersection point is found, we can only wait until our ships meet at it. It is then that we will be given control over the astronaut in distress (the distance should be less than two kilometers!). Once at this point, synchronize the speeds by selecting his ship as a target on the map and setting the return thrust until the speed difference approaches zero. Now your orbits are almost identical, and the rescue procedure can begin. Switch to astronaut and go into outer space. Each suit has a rocket control system, or RCS, built into it. Turn it on.
It consists of small jet engines running on compressed gas. Such systems are also installed on ships and serve to move them in space without changing direction or, on the contrary, to change direction without changing speed. Symmetrically located nozzles are placed so as to be able to direct the thrust along any axis and at the same time be as far as possible from the center of mass. If we want to move, say, forward, then the upper and lower motors are activated, compensating for the rotation around their axis from each other. We will later use such systems in similar situations to dock ships, and we will perform the same actions. At the moment, the RCS of the spacesuit has already been installed and configured. Please note that the spacebar allows you to turn and stabilize the ship or astronaut in the direction of view, this is very convenient.
This is what RCS looks like in reality.
So, a rescue shuttle is hovering nearby. Check your speed relative to him by targeting him. If this speed is almost zero, everything is fine, if not, then compensate for it with return thrust. Now give thrust towards the target (this is easiest to do by simply turning to face it). Our direction mark should coincide with the target mark, showing that we are moving straight towards it. if this is not the case, correct by direct acceleration up/down or left/right (RCS gives us this option). Our speed relative to the ship has increased, but that’s how it should be, we’re getting closer. Don’t get carried away so you have time to slow down before the ship. When there is a short distance left, apply thrust from the target to slow down. Look at which side the door is on. If it is on the opposite side of our ship, then give direct thrust up/down or left/right, trying to stay facing the ship. When the hatch is directly opposite, give forward thrust and enter the ship at very low speed. Now all that remains is to land it, which will not be difficult if the structure is assembled well and you have fuel left.
The eagle has landed.
About rovers and prospects.
Having assembled a decent crew, you can begin a lunar expedition. With your knowledge of orbital mechanics, it will be quite easy to fly around the moon and return, so we will immediately start landing and returning. For such a task, the researched technologies of the fourth level are enough, but it is better if the ship has more powerful engines. We’ll attach a fuel tank and engine to our command module to take off from the moon and head to Kerbin. To land on the moon, we will attach the landing gear (here there are possible options for installing the landing gear on different stages of the rocket, but we will consider the simplest option). A simple tripod is enough. Since the landing will be vertical, we need to make sure that our ship with tank and engine is not too high, otherwise when landing, especially on sloping terrain, it is too easy to roll it on its side. From below, another liquid fuel carrier must be attached to this, which will have to slow down when descending to the moon. And finally, to put this into orbit of the earth and increase the speed in orbit, we need powerful accelerators to give us the initial push. You should get something resembling the design in Fig. 16.
If you want, you can also try to land a rocket that will carry a lunar rover for your astronauts. It’s not good to stomp on the moon on foot.
When everything is ready, launch the device into orbit. If we accelerate while in orbit, then the opposite point of the orbit will move away from us. Move it far enough so that it crosses or touches the moon’s orbit (see. rice. 17). Since our spaceport is located on the equator, and the moon is in an equatorial orbit, we do not need to change the inclination.
Now there are several options. You can just wait until the trajectories of the moon and the ship meet. This will save fuel, but may waste time. If there is enough fuel, but there is no way to get to the moon, you will have to change the trajectory with thrust inward or out of the orbit so that you can still meet (these maneuvers have already been used when ships meet in orbit, it’s just that this time combining orbits with the moon is expensive and therefore not necessary, but the principle does not change). An accurate hit this time is not necessary; it is enough to fly close enough for the gravitational field of the moon to become stronger than Kerbin.
The gravity zone of the moon is conditional, since in reality the rocket will be affected by the gravitational forces of all large objects in proportion to their distance, but the game calculates only one body around which the ship rotates, so when entering the gravitational field we will immediately be shown a new trajectory. It is unlikely to be closed, because inertia will force it to quickly exit and return to Kerbin orbit. To prevent this from happening, we need to reduce inertia, and therefore our speed relative to the moon. It is not necessary to do this sharply and directly at the initial point of the trajectory, this will lead to a decrease in speed to almost zero, followed by a fall to the surface at a point that may well turn out to be poorly suitable for landing or simply unsuitable for our purpose.
It is worth falling blindly if you are very low on fuel, in other cases it is better to slow down so that the pericenter is not far from the surface, and then fly to it and complete the braking, ultimately obtaining a stable orbit. If we need a specific landing site, then the orbit must be adjusted so that it passes exactly above this point, and almost above it give back thrust until the speed drops to zero. Zero speed means that you have extinguished the inertia relative to the rotation of the surface, and all that remains is to fall vertically down, it is easier to aim at the desired point, and it is much easier to land the ship exactly.
At the very surface you will again have to slow down to almost zero and throw away the tanks, leaving the tripod and starting the last engine. With this we finish braking. The lower our speed, the less likely it is that the chassis will not support the weight of the ship when landing.
You can take a lunar rover with you to another planet or satellite, and then subsequently tasks requiring data transfer from the surface will be completed in seconds.
To take off, you just need to give thrust, and the rocket will easily go beyond the gravitational field of the moon. Strictly speaking, since the body is affected by the gravitational forces of all objects, it should be said that the attraction of the moon will weaken so much that the predominant gravitational force is the attraction of the planet, and in the same way, moving away from it will entail the predominance of the gravitational field of the star, but in the game this is reflected schematically, so it is easier to talk about a conditional zone of influence. However, regardless of the difference between these concepts, after taking off from the moon we will again find ourselves in the circular orbit of Kerbin. Now you need to slow down until the flight path lands directly on its surface.
If we need to save fuel, then we can begin this deceleration even when taking off from the moon; it is enough to wait until the moment when the section of its surface on which the rocket stands turns opposite to the direction of the moon’s orbital movement. Thus, it turns out that as we move away from the surface, we also reduce the speed relative to the planet, which will reduce the impulse needed to slow down after leaving the gravitational field of the moon, and therefore save fuel.
It must be said that the entry into the atmosphere will take place at very high speeds, which means that our landing module will encounter strong air resistance and heat up against it. To increase resistance, you need to fall with the bottom against the air flow (Fig. 18). The small capsule is light enough for quick braking, but later, when we land heavy modules, we will have to install special heat shields on the bottom to prevent the skin from overheating. However, it is the atmosphere that will serve as an excellent brake, slowing down the capsule until the parachute becomes possible. At the same time, you must try to enter the atmosphere at a large angle, so as not to get into its dense layers at high speeds, but have time to slow down without overheating the ship.
Now the space program has reached the milestone of 1969, when the United States first landed an astronaut on the surface of the moon, and you learned the principles of orbital mechanics just enough to be able to complete any task in the game, the rest is up to the engineers.
What to do next is purely a matter of your imagination. Assemble a scientific station in orbit piece by piece? Send a fifty-ton drilling complex to another planet? Create a network of satellites that transmit data from any planet automatically? Experiment. There are a lot of problems that deserve to be solved.