My notes from European Space Agency video about the Soyuz launch sequence
Part 1
Soyuz uses the Baikonur space launch system in Kazakhstan, for assembling, preparing and launching rockets.
Jurij Gagarin was launched into space from Baikonur location 50 years ago.
Three astronauts can accommodate in Soyuz for the ISS trip.
The rocket length is 50 m and diameter of 10 m, a total mass of 310 tons.
Soyuz is equipped with an emergency system, called launch escape tower, to evacuate astronauts in case of a major malfunction.
The emergency system was used twice, in 1983 and 2018.
Launch sequence:
- 30 sec - the pitch maneuver, which gets a proper orientation towards the desired orbit
- 40 sec - the acceleration on the crew members increase to 1.5g
- 50 sec - the altitude of 11 km, Max Q
- 110 sec - the altitude of 40 km
- 120 sec - boosters separation, the second stage
- 150 sec - the acceleration on the crew members reaches max 3.5g
- 180 sec - the spacecraft is fully exposed to space
- 5 min - the altitude of 170 km; speed of 13 250 km/h; second stage separation
- 9 min - the spacecraft reaches 220 km and separates from the rocket; microgravity
Part 2
Now Soyuz is speeding 30 times faster than a regular plane; it has a single purpose to catch up and dock with the ISS.
The ship is still more than 100 km away from the ISS and has to do a series of maneuver to catch up with the ISS.
ISS is orbiting Earth every 90 min on a fairly constant orbit (Earth is rotating though)
Even though technically it’s possible to launch Soyuz at any time, the most efficiently is to launch the ship once the ISS passes by Baikonur.
It shortens catching ISS time from 2 days (short path) to 6 hours (also called long trajectory)
Rendezvous is defined as a sequence of maneuvers to approach two vehicles in space.
Soyuz altitude: 220 km; Station altitude: 420 km
Two maneuvers are required: first maneuver, Hohmann transfer, increases altitude to around 320 km and reduces the angle between ships (a ship on lower orbit moves faster)
Soyuz has contact with Earth only when it flies above Russia.
In the spacecraft, there is a separate module with sleeping bags and toilet.
The second maneuver, Bielliptic transfer, brings the ship to the ISS altitude and to the correct speed.
Just before reaching ISS, Soyuz performs an additional sideburn, and makes a collision between two ships impossible.
On-board computer called KURS calculates all burns.
In some cases it might be required to run docking procedure manually (e.g. redocking to another dock, make a place for new ships)
Part 3
ISS is orbiting Earth since Nov 1998 at 28 000 km/h.
After a few months of work on ISS, astronauts have to come back to Earth.
The return journey of the spaceship takes 3.5 hours to reach a landing zone is Kazakhstan.
After detaching, and free fall (can’t use engines close to ISS), the spaceship makes a small burn.
The next critical stage is the deorbiting burn to force the Soyuz to reduce the speed and altitude.
Burn start time and length sequence is very critical to make a smooth entrance into Earth’s orbit; Normal entry temperature burn against the atmosphere is 2 000 C.
Before entry, the spaceship separates into three modules, out of which only the descent module makes a safe comeback to Earth.
Maximum acceleration reaches 4 g at an altitude of 35 km.
Parachute opens at an altitude of 8.5 km.
Just before landing, the retro rockets fire 70 cm above the ground to reduce the impact.
Ground rescue team helps the crew members to leave the capsule.