Geekly Articles each Day
📜 ⬆️ ⬇️

On the "Union" to the ISS and back



In Orbiter there are adventures from which breathes something subtly homely. In fact, what could be more familiar to flying on the Soyuz to the ISS, if this event occurs in reality four times a year? The excellent quality of add-ons that were made by enthusiasts promises a lot of positive emotions, and the MCC archives with information about real flight allow you to dive deeper into the atmosphere of modern cosmonautics.

A warning


This flight is difficult for beginners. If you have no experience in Orbiter flights and understanding of terminology, I recommend first to practice at the PTK NP:


And if you are too lazy to fly in a simulator, watch a movie. Better than there, hard to tell.



')

Flight plan


  1. Start from the Earth.
  2. Rendezvous maneuvers with the ISS.
  3. Rapprochement and docking.
  4. Return to Earth.


Flight preparation


For the flight we need:
  1. Orbiter .
  2. Addon Soyuz FG / U v1.2 .
  3. Addon International Space Station v.3.2 .
  4. Addon Aerobrake MFD .
  5. Addon Baikonur Surface Tiles v1.1 (optional).


Installation and Setup


Addons are installed in the following order: first Soyuz FG / U, second ISS. Archives simply unzip to the Orbiter folder.
If you want to set the texture of Baikonur and make the start more beautiful:
  1. Unpack textures into Orbiter's textures folder.
  2. Add the lines from the readme to the baikonur.cfg file not in ORBITER \ CONFIG \ EARTH \ BASE , but in Orbiter \ Config \ Earth \ M. The fact is that ISS scripts use a “different” solar system with different configuration files.

Make sure the Limited fuel option is set in the Parameters tab.
Orbiter will show the program error window after exiting the script. If this is annoying, in the Extra tab - Debugging options - Orbiter shutdown options, select the Respawn Orbiter process mode.
In order for the Soyuz not to fall apart when landing on a ballistic descent, open the Orbiter \ Scenarios \ International Space Station \ 2006 \ 052 folder . Soyuz TMA - 8 is the only file found there in any text editor and delete the ALLOW_BALLISTIC line. Otherwise, because of the bug, the "Union" will always go into a ballistic descent instead of a controlled one when landing.

Stage 1. Starting from Earth


I chose the flight scenario of the Soyuz TMA-8, mainly because it is one of the last in the collection of scenarios (the ISS is already quite large), and the launch takes place during the day. In principle, no one bothers you to choose any other scenario of the "Union".
Soyuz TMA-8 was launched on March 30, 2006 with a crew from cosmonaut Roscosmos Pavel Vinogradov, NASA astronaut Jeffrey Williams and first Brazilian cosmonaut Marcos Pontes ( brief biographies page ):


Start early in the morning, so this photo is still night

Start and launch occur fully automatically. The only note is that in order to avoid glitches, I do not advise putting acceleration time greater than x10 on launch, and more than x100 in all subsequent flights .


Real start


And orbiter


And such frames are only in the simulator. The third stage after separation drains tanks, moving away from the newly withdrawn "Union"

I recommend to save the script by Ctrl-S . Well, you can turn on some cosmic ambient for greater atmospheric pressure:



Stage 2. Maneuvers for the rendezvous with the ISS


So, we are in orbit, the solar panels and antennas are open, we begin the path to the ISS. First of all, it is necessary to note the features of the Soyuz spacecraft in the simulator:
The ship has four additional information screens that can be switched using the U button:

Movement Screen:

This screen displays:

Electrical system and control screen

This screen displays:

Docking screen

It contains useful data on the orientation and speed of rotation of the ship, as well as on the state of the docking pin.

Blank screen
In this mode, additional information is not displayed and can not prevent other MFD.

The general rule of flights on the "Union" - not in a hurry, do not abuse the automatic modes of maintaining orientation, save fuel .
It is better to turn around in two or three minutes with a couple of pulses than to spend a few kilograms of fuel on an automatic turn.
Pulse mode is very unusual for Orbiter, and it practically does not occur in other ships, so you need to get used to it.
Also in the control keys there is a very non-ergonomic key that interferes with the role-making component - depressurization of the household compartment (normally done before separating the compartments at the landing stage) - button A without any modifiers. Inadvertent pressing (and on Shift-A the MFD of orbital alignment is called) - and the depressurization of the household compartment makes it impossible for the normal role-playing continuation of further flight.

The combination of the planes of the orbits

Let's look at the parameters of the real flight orbit :
ParameterReal valueValue in simulator
Apocenter242 (± 42) km245 km
Pericenter200 km (+ 7 / -22) km195 km
Orbit inclination51.67 ° ± 0.058 °51.60 °

If it were not for the inclination error, the elimination would be almost perfect. And so we have to first combine the orbits of the "Union" and the ISS:



Whole half a degree. Too much, but nowhere to go. I propose to perform a correction on the first turn (in reality, the first maneuver was carried out four hours after the start). The next node is ascending, which means that it will be necessary to deploy the ship "down" from the plane of the orbit. Do not forget to open the lid of the KTDU a few minutes before the knot - firstly, it blocks the engine start, and secondly, the MFD with the lid closed cannot calculate the pulse duration. Let us recall the rule of thumb - the engine starts at the moment when half of the estimated time of engine operation remains before the node:


Begin maneuver


Result

At the end of the maneuver, it is worthwhile to work by shunting engines for the maximum combination of orbits. Please note that we have spent as much as 20% of the fuel.
After the maneuver, I recommend to transfer the APS to the minimum pulse mode, turn on the automatic system for maintaining solar orientation (it is quite economical) with the K button and save the script.

Synchronization of the orbit with the ISS

We look at the parameters of the orbit of the "Union" and the ISS according to the MFD "Orbit":



Between us and the ISS is almost half a turn (the so-called phase angle). This was done specifically so that in two days of flight (I’m reminding you, 2006 is the year, there is no talk of a six-hour docking scheme yet) "Union" could not hurry to catch up with the ISS.
How will we synchronize the orbit? I propose to divide it into the following stages:
  1. Wait until the phase angle decreases.
  2. Raise the apocenter to the intersection with the ISS orbit. I recommend performing the maneuver in the apocenter of the current orbit in order to minimize the difference in velocity between us and the ISS. If we raise the apocenter from the pericenter of the current orbit, then at the apocenter our speed will be noticeably lower, and the difference between the almost constant speed of the ISS in a circular orbit will be greater.
  3. Synchronize orbits, raising pericenter.
  4. Perform a deceleration maneuver relative to the ISS in the near zone.

Looking forward to reducing the phase angle .
Patience is one of the essential qualities of real astronauts. You are waiting for a space flight and are preparing for several years (especially bad luck astronauts have been waiting for their flight for 19 years!), Wait a couple of days in orbit - this is nonsense. We are planning a maneuver in the MFD "Go":


March 30, 03:52 UTC, ends the first round


March 30, 19:40 UTC, it's time to get ready for the maneuver
A word of advice: it will be easier to prepare for the maneuver if you are not in a hurry to orient the ship on the opposite side of the orbit against the orbital velocity vector (for braking). After half a turn of the "Union" "he" will take almost the right position, which will remain only slightly adjusted.
The result of the maneuver on MFD “Transition” is not clearly visible - the lines merge. Switch to MFD "Orbit Synchronization":



Not bad, we have four more orbits to prepare for the synchronization of the orbits. Turn on the orientation mode on the Sun again and wait:



Our task is to raise the pericenter to reduce the parameter DTmin to zero:



Convergence and docking - through the coil. Funny, the time counter shows that instead of a real two-day scheme, it turned out to be one-day — that was how the Soyuz once flew to the Salyut orbital stations. The scheme is not very successful - by the end of the first day, the period of adaptation to weightlessness is the brightest, and 40-60% of the crew (according to statistics) suffer from nausea. But we are not threatened in virtual flight, so feel free to go to the dock.

Required docking preparation operations:
Find out which node we are connecting to . Historically, the Soyuz TMA-8 interfaced to the nadir node of the Zarya module, in the numbering of the script it is node number 1.
Set up MFD "Docking" . We turn on the MFD “Docking”, select the first docking station and output the data to the ILS.
Turn off the orientation system of the ISS. Press F3 to open the ships menu and select ISS. Pressing the End button above the block of cursor keys turns off the orientation system. Switching screens similarly to the "Union" for U make sure that the system is turned off:



Now the ISS has ceased to turn slowly around its axis, and we can calmly dock.
Calculate the start of braking . On the one hand, we do not want to crash into the ISS. But, on the other hand, we do not want to slow down too far, so that we do not have to spend the fuel again on acceleration, braking and orientation. Using only the school formulas of acceleration, speed and distance traveled, not taking into account fuel consumption and weight reduction of the ship, we get the following simple sign, which tells us at what distance to start braking for a given rendezvous speed:

Please note that with a speed difference of 100 m / s, only 6 km is enough, and with a speed difference of 200 m / s, 23 km is needed! Therefore, we did our best to reduce the speed difference earlier in the script.

Stage 3. Close and docking


Here is a diagram of the real convergence and docking of the Soyuz TMA-8 from here :


We, of course, have other flight parameters, because we performed other maneuvers. But from this picture there is one useful advice - it is more convenient to dock during the day.
And we are also approaching the ISS:



The range of 30 km, it is time to turn against the velocity vector relative to the ISS.



The distance is 3 km, the speed of approach is 20 m / s. If you look again at the real docking scheme, we go at the same speed, the MCC will not penalize us for speeding and dangerous maneuvers.



The range of 1.2 km. The ISS is clearly discernible and is approaching simply with frightening speed. The only thing that reassures is that it’s clear that we are a little overshooting and flying a little to the side, and not hitting the station.



I started to slow down with 400 m, let it be a small margin. Distance 200 m, relative speed 0. If you have night, it is better to wait for the exit from the shadow of the Earth - it will be more convenient to dock.

Docking

And where, strictly speaking, is the nadir docking assembly of the Zarya module? Here is a photo of the ISS of July 2006 from the Space Shuttle mission STS-121:



This photograph was taken from the opposite side of the ISS relative to the previous picture. Thus, we now need to move back and down ( where the ISS is up, down, right and left ), turn the ship with the docking station up and proceed to docking. I remind you that we have not so much fuel, so it is worth maneuvering carefully and not in a hurry.



ISS is much smaller than today, but still impressive.
Turn off the MFD with the PWR button on the screen, transfer the additional information screen to the docking mode, select the docking target (ISS) using Ctrl-O , press the O button to select port 0 (obviously, the IT people did the script, just numbering from zero start :)) and release the docking pin the Y button.



The nadir assembly of the Zarya module is indicated by an arrow. But our task is to aim not directly at him, but at a target for manual docking . The point is that the point from which we are looking is located at the site of the periscope, and we see a picture, as if we were looking at the FAC (special space viewfinder). The “point of view” of the periscope is slightly away from the node, so we must aim at a special target. The main trouble is that the target may not be visible, and even the included headlamp does not illuminate it. If you do not understand how and where to aim, turn on the MFD “Docking” again, everything becomes clearer with it. Here is the correct position:




Appearance

There is a dock! What is especially nice - the fuel is still 513 kg, as much as 58%!

Stage 4. Return to Earth


For a successful and comfortable return to Earth, we need the coincidence of the following parameters:

On the MFD "Map" it looks like this:



We undock from the ISS via Ctrl-D .



We look at the landing scheme of the real “Soyuz TMA-8” and the coordinates of the landing stages :

It is important for us that the longitude of the start of braking is 324 °, i.e. 36 ° west longitude. The longitude of the landing site is 67 °, so the Soyuz begins to slow down ~ 100 ° degrees to the landing site.
Preparing for landing. Turn on MFD “Aerodynamic braking”, select “Soyuz Landing Site” as the target and switch it to map mode. Orient the ship against the orbital velocity vector (stern ahead). We are waiting for 36 ° west longitude and begin braking. We brake until the estimated shortfall is about 100 km.



At an altitude of approximately 150 km, we unseal the household compartment (button A ) and separate the compartments with two taps J :



After separation of the compartments, we select the landing site again as a target. The lander in reality is controlled only by roll and pitch, in the simulator there is also a yaw. We occupy the position "stern ahead" and at first do not interfere in the management - the ship in the atmosphere orients itself:



If necessary, you can perform small maneuvers roll, driving lift. It should be noted that the space for maneuver is very limited, you can fix only small errors:



Parachutes and soft-fit engines are entered automatically:



An error of 15 km, the maximum overload of 4.7 g - an excellent result for manual landing!




Marcos Pontes returned to Earth on the “Soyuz TMA-7”, the third on the “Soyuz TMA-8” landed Anusha Ansari - a native of Iran, a US citizen and the fourth space tourist.

Conclusion


Translated into Russian manual .
The entire series of publications on Orbiter .
For real manned launches and landings, there is almost always a broadcast on NASA TV , text and video broadcasts can also be expected, for example, in the Roscosmos VK group or search for links to broadcasts on the Cosmonautics News forum .

Source: https://habr.com/ru/post/240103/

More articles:


All Articles