Flight Mars-Earth: ballistic tricks and atmospheric surfing

From Earth to Mars, we already flew in Orbiter , we should return back. And as a complication of the task, we will try to go back quickly and use the Earth's atmosphere for an accurate landing at Cape Canaveral to its fullest.

Flight plan

For convenience, we divide our flight into the following stages:

1. Starting from Mars
2. Acceleration from Mars Orbit
3. Maneuver to intercept the Earth
4. Combination of orbital planes and intermediate corrections
5. Entry corridor, aerodynamic drag on the Earth’s atmosphere and accurate landing

Flight preparation

In addition to Orbiter, we need only one addon - AerobrakeMFD . For your convenience, I posted on Google docs save the flight stages. If you want to do only some part of the flight - download the archive and unpack it in the Scenarios folder of Orbiter.



It is assumed that you are familiar with cosmic ballistics, the Orbiter simulator, and, at least, have read a series of publications about flights . If not, read at least the publication on the flight Earth - Mars . Basic terminology and hotkeys will not be explained here.

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Stage 1. Starting from Mars

Before starting the script, go to settings. Turn on the infinite fuel mode and turn off the damage simulation. The latter is necessary because the atmosphere of the Earth is very dense, one careless movement, and our ailerons will fall off. However, if you want, you can add adrenaline by turning on the damage simulation.





To start, choose a script from the base delivery: Delta-glider - Brighton Beach :





After launch, we find ourselves on the moon. It should be so. Pressing F3 , switch to another ship that is based on Olympus on Mars. His tail number GL-02 :





All we are on Mars:





“Check the pressure of hydraulic systems - done. Check the readings of the control systems of the main reactor - completed. Launch cosmic ambient - done. The prestart control card is completed, ready for takeoff. ”





Low gravity of Mars allows you to start up vertically on lifting engines without any problems. We turn on the automatic maintenance of the horizon level ( L ) and transfer the lifting motors to maximum thrust. After takeoff, we remove the chassis, turn on a course of 90 ° and begin acceleration:





In the process of acceleration, we maintain the orientation mode on the horizon level and smoothly clean the lifting engines. When the height of the apocenter is ~ 100 km, turn off the sustainer.





In the area of ​​the apocentre, we turn on the marching engine again and enter a circular orbit around Mars:





At an altitude of 100 km there are still some remnants of the atmosphere, but we are not afraid of it - in this orbit we will be no more than a couple of turns. Stage 1 is over. Saving this moment - the file "01 Low Martian Orbit.scn"

Stage 2. Acceleration from Mars Orbit

Since Mars is farther from the Sun than the Earth, you need to slow down to enter a course that intersects with the Earth. Therefore, it is better to perform the maneuver on the descent of Mars orbit on the day side of the orbit so that the second cosmic velocity for Mars is subtracted from its orbital velocity:





Let's prepare the MFD for the maneuver and start overclocking according to the indications of the MFD “Transition”:





To intercept the Earth, we need to perform a complicated maneuver, so at this stage we will stop accelerating when MFD Orbit shows that we have reached the second space mission and are leaving Mars orbit:







Stage 2 is completed, saving - “02 Acceleration from Mars Orbit.scn”

Stage 3. Maneuver to intercept the Earth

Accelerate time until we are out of the gravitational influence of Mars:





We are planning a maneuver to intercept the Earth in the MFD “Transition”:





The proposed solution is working and economical, and you can easily fly along this trajectory. But the flight will take about nine months (look at the current position of the Earth and the position at the intersection point - the Earth will pass approximately 3/4 of the orbit). Is it a long time, can you somehow speed up the flight? Yes, you can fly almost twice as fast. To begin with, let's perform a braking maneuver according to our original plan:





Intermediate conservation - "03a Gomanov maneuver.scn"



Look at the left MFD "Synchronize Orbits." By pressing the MOD button on the MFD, I chose not the distant intersection point of our orbit and Earth, but the near one. We see that we will be there in 14 mega seconds, and the Earth in 11. That is, at this point it will overtake us. So, we need to accelerate to be at this point at the same time as it. But what course? Let's think about it. If we start to accelerate along the orbital velocity vector, we will return to the situation at the last step, it does not make sense. If we accelerate towards the Sun, this will also not make sense, because the intersection point will shift to the left, and we will have to accelerate very much to catch the Earth literally in a straight line to the Sun. So, we need to accelerate somewhere in the range of 30-60 ° from the direction to the Sun:





Let's try overclocking by 45 ° from a straight line to the Sun, i.e. with respect to the orbital velocity vector 315 °:





The time difference drops noticeably, but the point itself goes in an orbit to the right. So, you need to accelerate the "left". Focusing on the Tg-ToR parameter (after how many seconds the Earth will be at the selected point) and visually on the movement of the point on the MFD, we maneuver in the course range 290 ° -310 ° until the DTmin indicator decreases to a minimum:





Pay attention to the orbit. We accelerated as if we were returning not from Mars, but from Jupiter. This is very inefficient in terms of fuel, but then we will be on Earth in less than 4 months. Stage 3 is finished, saving - “03b Change orbit.scn”

Stage 4. Alignment of the orbit planes and intermediate corrections

Check the angle between the planes of our orbits:





We were unlucky, we recently passed a node, and in order to precisely align the orbital planes, we will need two maneuvers. But this is for the better, there is much to learn. First of all, since we don’t get a knot to the point of meeting the Earth, we need to move it there. We start the usual maneuver of combining the planes of the orbits. We are not far from the descending node, so we will accelerate "up". Notice that the node line begins to shift. When the descending node takes place between our current position and the meeting point with the Earth, stop the maneuver:





Great, now we will speed up the time to the descending node and precisely match the orbital planes there:





After an exact alignment of the orbit planes, we will carry out an orbit correction for an exact encounter with the Earth. By taking a position along the orbital velocity vector, we will give shunting pulses forward / backward and left / right. In which direction DTmin decreases, there we give impulse:





Well, the correction is made. For 5 megasegund before the meeting, it makes no sense to carry out the correction (the parameters will not have time to “spoil”), we will repeat it for 2.5 and 1 megasecond to the meeting point:





Stage 4 is completed, saving - “04 One megasecond to Earth.scn”

Stage 5. Entry corridor and aerodynamic drag on the Earth’s atmosphere

We waste time until the Earth’s gravitational influence becomes dominant:





The earth is turned to us by the night side, it is convenient. Our task is to conduct a maneuver so that the pericenter of the orbit would be equal to 50 km, and the orbital velocity vector would be directed to the day side. In this case, we will comfortably brake on the day side of the Earth:





Intermediate storage "05a Entrance Corner.scn" .



Before entering the atmosphere, set the elevator trimmer as far as possible upwards and take a position with a roll angle of 90 °. The plan of our braking is as follows. We will occupy a height of 40-50 km and we will suppress the speed, while simultaneously suggesting Cape Canaveral. When our speed becomes less orbital, we will emerge from the atmosphere and enter it again in the target area.

900 km, the Earth is near:





Intermediate conservation "05b Nine hundred kilometers.scn"



In the area of ​​the pericenter, we are maneuvering with a roll - simultaneously extinguish the vertical speed and the vertical acceleration:





From the point of view of physics, an amusing situation has turned out. We are in a zone of steady braking. It is just to be here and it is very convenient to brake. But if we negligently allow a large vertical speed, then we either fly out of the atmosphere, like a flat rock out of water, or crash into the ground at a tremendous speed. An interesting feeling, a kind of space surfing ...

In no case do not release the aerodynamic brakes, you are likely to lose control. We control the vertical speed and acceleration, do not forget to glance at the map on the right - the inclination of the orbit changes, we need to be led to Cape Canaveral:





The ship goes through the atmosphere like a knife through butter. Comfortable braking conditions, a little more than one "same." In reality, such devices did not build humanity. The ship actually goes into polar orbit, and the first turn is not far from the Cape (yes, sometimes his name is Cape, with a capital letter). One has to be careful, we have almost lost the orbital speed, and the trajectory should not be allowed far to the side:





When the trajectory goes to the side, we sharply turn over on the other side and quickly minimize the vertical speed:





When the speed falls below the orbital, the orbit on the map is torn apart. After we start “not reaching” the target, we quickly turn to the zero pitch angle - it's time to escape from the atmosphere!





The atmosphere is behind, but the speed is lower than the first space one, and we turned into a ballistic missile, or, more precisely, a Zenger bomber . We are preparing for the final landing area - we will translate the onboard radios to ILS frequencies of Cape Canaveral. ILS frequencies are available at Ctrl-I , these are 134.20 and 132.60 MHz:





Intermediate storage "05c After the first braking.scn"



We put them on the MFD ( SL- / SL + selects the channel, << / >> adjusts the whole part, </> - fractional):





Again the boundary of the atmosphere. The main thing is to extinguish the vertical speed and not allow deviations of the trajectory from the target according to the MFD “Aerothermo”:





Another bounce from the atmosphere:





Again we begin to decline:





We are approaching the goal. We release aerodynamic brakes ( Ctrl-B ) and prepare for active maneuvers:





To the goal quite a bit, and the speed drops. We maintain a low speed of descent in order to slow down as smoothly as possible:





We went to the target area:





Fly target, this is normal. We remove the aerodynamic brakes and are actively deploying for the landing approach:





Turned around, turn on ILS (MFD "Indicator of horizontal situation" Shift - H ). Unfortunately, ILS works at an extremely small distance, so far just trying to get to the WFP area:





The course-glide system works in exactly the same way as in aviation, the pilot is required to control the ship so as to maintain the vertical and horizontal indicators in the central position:





When the runway is visible (night, but the weather is good), we go in for a landing, focusing on the runway visually and along the course-glide system. We try to catch the glide path. It is difficult, if necessary, release the aerodynamic brakes or give impulse engines to accelerate.





After touching the strip, we brake (brake of the left wheel - , (comma), brake of the right - . (Full stop)). There is a landing!

Conclusion

As KDPV used photo from the orbital gallery of Alexander Samokutyaev.

Translated into Russian Orbiter's manual .

The whole series of my publications about flights in the Orbiter .