Space tunnels and iron on the head or why do we need the Vostochny cosmodrome

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

The other day I was asked to consult the infographic of RIA Novosti, dedicated to the first launch from the Vostochny cosmodrome. And there will be one major simplification due to the limitations of the format of the material. In fact, we do not need the Vostochny cosmodrome because the majority of civilian launches take place from the Baikonur cosmodrome.

But in order to explain why we need it, we will have to tell why the orbit of a spacecraft can be compared to a tunnel, and also explain what kind of "iron" falls from the sky, and on whom it falls.

Tunnel in the sky

The physics of orbital motion is completely counterintuitive. Rather, it is the opposite of what an ordinary person imagines. And even good films, seemingly striving for realism, give a completely wrong idea of how satellites and spaceships fly. Remember "Gravity", which famously flew from the Hubble to the ISS, and then to the Chinese station? Even if we discard the difference in orbital heights, one parameter of orbital motion kills even the slightest chance of such flights. This parameter is called "orbital inclination".

Orbit inclinationis the angle between the plane of the satellite's orbit and the plane of the equator (for an Earth satellite)

For example, for the case of "Gravity" the picture will be like this:

And the fact that the planes of the orbits do not coincide at all is not a problem. The real trouble is that for a low circular orbit (and the Hubble, ISS, Tiangong and the mass of other satellites are a low circular orbit), the change in inclination is very expensive. To "rotate" the orbit by 45 °, we will have to change our speed by about 8 km / s, the same amount as we needed to enter orbit. And changing the speed is a waste of fuel and reset of stages. That is, if a rocket with a mass of 300 tons puts 7 tons into orbit, then after a change in inclination by 45 °, only 150 kilograms will remain. In fact, each orbiter flies inside an invisible tunnel, the diameter of which depends on its ability to change its speed. Therefore, when launching satellites, they try to bring them immediately to the desired inclination.

Beaten roads

What inclination is used for existing orbiters? There are many satellites in Earth's orbit now:

If you look closely, you can see that there are more satellites in some orbits. Here is a picture showing the movement of satellites relative to the Earth:

Geostationary orbit (green). It is a circular orbit with an altitude of 36,000 km and an inclination of 0 °. The satellite on it is located above one point on the earth's surface, therefore, in the picture, the correct geostationary orbit is indicated by a green dot. Green loops are faulty satellites or out of fuel. The geostationary orbit is under the disturbing influence of the moon, and you need to spend fuel just to stay in place. This orbit is inhabited by telecommunication satellites, which are profitable, so it is already difficult to find vacant places on it.

GLONAS / GPS orbits (blue and red). These orbits have an altitude of approximately 20,000 kilometers and an inclination around 60 °. As the name implies, they carry navigation satellites.

Polar orbits (yellow). These orbits are inclined in the region of 90 ° and the altitude is usually no more than 1000 km. In this case, the satellite will fly over the poles every revolution and will see the entire territory of the Earth. A separate subspecies of such orbits are sun-synchronous orbits with an altitude of 600-800 km and an inclination of 98 °, in which satellites fly over different parts of the Earth at approximately the same local time. These orbits are in demand for meteorological, mapping and reconnaissance satellites.

In addition, the ISS orbit with an altitude of 450 km and an inclination of 51.6 ° should be noted.

Heartless geography

Well, well, we figured out the moods, the reader will say. And where does the cosmodrome? The fact is that there is such an unpleasant physical law:

The initial inclination of the orbit cannot be less than the latitude of the cosmodrome

Why is that? Everything becomes clearer if we draw the trajectory of the satellite on the map of the Earth:

If we, starting from Baikonur, begin to accelerate to the east, then we get an orbit with an inclination of Baikonur latitude, 45 ° (red). If we start to accelerate to the northeast, then the northernmost point of the orbit will be north of Baikonur, that is, the inclination will be greater (yellow). If we try to cheat and start accelerating to the southeast, then the resulting orbit will still have the northernmost point north of Baikonur and, again, a greater inclination (blue).

But such an orbit is physically impossible, because it does not pass through the center of mass of the Earth. More precisely, it is impossible to fly with the engine off. You can be in such an orbit for some time with the engine running, but the fuel will run out very quickly.

Thus, if we want to launch satellites into geostationary orbit not from the equator, we need to somehow reset the orbital inclination, consuming fuel. It is these costs that explain why the same Soyuz-2.1a rocket successfully launches satellites into geostationary orbit from the Kuru cosmodrome near the equator, but is not used for these tasks from Baikonur.

Russia is a northern country. And if satellites can be safely launched into polar and GLONASS orbits from Plesetsk, which is located at a latitude of 63 °, then for a geostationary orbit, the further south the cosmodrome is located, the better. And here the second problem comes into force - not every territory is suitable for a cosmodrome.

Step on kumpol

All modern rockets, when launching a satellite, release spent stages and nose fairings that fall to the Earth. If the crash site is in another country, you have to negotiate with that country for each launch. Therefore, for example, the minimum inclination of the Baikonur cosmodrome is not 45 °, but 51 °, because otherwise the second stage will fall into China:

And at the place where the first stage fell, you have to negotiate with Kazakhstan and pay for the use of these areas. Sometimes problems arise and the launch of satellites is delayed. The areas of the fall have to be alienated rather big:

And in the European part of Russia there are no good places for a cosmodrome. I played with the maps, in the Caucasus you can dodge and try to launch from the region of Mozdok, but even then you will have to try so that the second stages do not fall into Kazakhstan. If you launch a rocket from the Crimea, then the first stage will fall into populated areas near Rostov-on-Don, and the second stage will again strive to fall into Kazakhstan. And that's not taking into account the infrastructure problems in both options. Against this background, you will look at the inclinations available for US spaceports and regret the heartlessness of physics and geography.

But we also have an east coast. And, if we place the cosmodrome there, then it will be possible to find remote areas for the fall of the spent stages for the most demanded inclinations: 51, 6 ° (to the ISS and geostationary orbit), 64, 8 ° (GLONASS, some Earth sensing satellites), 98 ° (into polar orbit).

Once again thesis

The Vostochny cosmodrome will enable us to launch payloads into the geostationary orbit and to the ISS without the need to coordinate these launches with other countries and pay them for using the exclusion areas. It is located in the southern part of the country and provides an initial orbital inclination no worse than Baikonur. It is irrational to build a launch complex for the new Angara launch vehicle at Baikonur (once again, coordination of launches and crash areas), but from Vostochny it will provide no less payload.

Nice little thing: the new launch complex with a service tower, like in Kourou, will allow launching western payloads, which must be mounted on the launch vehicle in an upright position.

A bonus is also the development of infrastructure, an impetus to the development of the territory, a science city, and so on.

UPD: infographic out. It's a pity that we didn't have time to redraw the placement of the satellites. Still very briefly, we tried to explain what is written here. In my opinion, it turned out nicely.