April 8, 2019 at 07:01Progress MS-11 Record: The Most Interesting Ahead
Last week, the Progress MS-11 cargo ship set a new record by docking with the ISS 3 hours and 21 minutes after launch. This is the second ship that flew in an ultra-short circuit - only two turns. Since 2012, when the Progress M-16M flew according to a short six-hour schedule, the flight time to the ISS has been decreasing, and now three and a half hours have reached - this is not the limit.
The launch of the cargo ship, photo CC "South" / Roscosmos
A. Sokolov. First experimental space station (docking of Soyuz-4 and -5 spacecraft)
A light historical irony is that the first dockings were just fast. The USSR holds an absolute speed record - on April 15, 1968, an unmanned Soyuz called Cosmos-213 docked with the Cosmos-212 of the same type only 47 minutes after launch. A record manned docking could also become Soviet - Soyuz-3, which was piloted by George Beregovoi, became close to the unmanned Soyuz-2 in less than an hour. But, alas, on the night side of the orbit, the astronaut was unable to correctly orient the ship, and the dock broke. So the record for the speed of manned docking belongs to the Americans. Launched in September 1966, the Gemini 11 docked with the Agen target after 1 hour 34 minutes.
Now such records cannot be surpassed, and the reason lies in orbital mechanics. In the USSR, there were two launch sites at the Baikonur cosmodrome, and the first ship could be put into orbit, which would pass over the cosmodrome a day later. At this moment, the second ship started, which immediately appeared near the first. For the first time, such a trick was turned with the Vostoks -3 and -4, and the cosmonauts Nikolaev and Popovich were at a distance of line of sight from each other. In the United States east of the spaceport there was an ocean, which allowed launching the second ship in the same orbit as the first, twice a day - in the ascending and descending section of the orbit. In any case, the launched second ship turned out to be at a distance of several kilometers from the target and could immediately proceed to dock.
Salyut-7 station and the Soyuz docked ship
When the operation of orbital stations began, these schemes stopped working due to the fact that the stations were launched into higher orbits, slowed down over time, and the Soviet also maneuvered independently. As a result, the USSR and the USA went different ways. In the USA, flights to the Skylab station took 6 turns or 8.5 hours. In the USSR, they switched to a daily regimen. The station performed the maneuver, preparing its orbit to receive the ship, which flew for about 24 hours. When the Mir orbital complex was launched in the mid-80s, it was too heavy for a special maneuver, so the ships switched to a two-day approach scheme. This was also influenced by another factor - as practice has shown, a day after the launch, the astronauts were keenly adapting to zero gravity, they felt worse and if necessary, switching to manual docking functioned less efficiently and made mistakes. A two-day docking scheme began to be used on the ISS, and before the beginning of the tenth years, cargo and manned spacecraft reached the station in 34 turns.
By the beginning of the tenth years, the transition to digital control systems on ships and launch vehicles allowed us to begin experiments with faster docking schemes. At RSC Energia, Rafail Farvazovich Murtazin, who has been working in the ballistics department since 1979 and now occupies the position of head of the department, has become the main enthusiast.
R.F. Murtazin, photo by Vera Tyukalova / “Your space sector”
But how long should I go? History has shown that the daily regimen is not optimal. In general, according to doctors and astronauts, the acute period of adaptation to zero gravity begins after about six hours in space. The second limitation was set by the technician - after the fifth orbit, the orbit shifts relative to ground-based measuring points, and it becomes much more difficult to control the ship. Initially, a five-turn scheme was developed, but it turned out that, due to the control features, it cannot be pre-tested on a cargo ship. So, it was precisely four turns or six hours that became the maximum permissible for a short circuit. Moreover, the methodology should be working constantly, a record for the record does not make sense. And for this it was necessary to learn how to solve technical and ballistic problems. The ISS is the heaviest station that has ever existed, and the possibilities for maneuvering it to form the required orbit are very limited. It is also large, with huge solar panels, and is noticeably inhibited by the remains of the atmosphere. And the density of these residues depends on solar activity, which cannot be predicted months in advance. In addition, sometimes you have to perform maneuvers to avoid space debris. There are also technical limitations - docking must be done on the day side of the orbit and in the visibility range of ground control points. Well, finally, you need to keep the orbit parameters compatible with future launches. And the density of these residues depends on solar activity, which cannot be predicted months in advance. In addition, sometimes you have to perform maneuvers to avoid space debris. There are also technical limitations - docking must be done on the day side of the orbit and in the visibility range of ground control points. Well, finally, you need to keep the orbit parameters compatible with future launches. And the density of these residues depends on solar activity, which cannot be predicted months in advance. In addition, sometimes you have to perform maneuvers to avoid space debris. There are also technical limitations - docking must be done on the day side of the orbit and in the visibility range of ground control points. Well, finally, you need to keep the orbit parameters compatible with future launches.
The main parameter that determines the possibility of docking is the phase angle and its allowable range. When the Soyuz or Progress is separated from the third stage of the launch vehicle, they are in low orbit at an altitude of approximately 210 km. The ISS flies higher at 400-450 km. To fly to the station, the ship needs to raise its orbit and aim at the point where the station will be after a while. Therefore, at the time of separation between the ship and the station there is a so-called phase angle (in the figure there is a bright sector).
The phase angle has a valid phase range. For a two-day scheme, it was just huge - 150 °. And in the four-turn circuit, it turned out to be much smaller - 22 degrees (phase angle from 18 ° to 40 °). And then it was necessary to apply technical tricks, for example, the ship performs the first two maneuvers in standalone mode, relying on the calculated, rather than the actual position. In subsequent maneuvers, when the withdrawal error became known, a correction was performed. Without this trick, the phase range would have fallen to about 15 degrees, and it would have been extremely difficult to stack an unevenly and unpredictably decreasing station.
Maneuvers and orbit altitude of the Soyuz MS-11 spacecraft, source
The first manned "Soyuz" went to the station according to a short scheme in 2013, and the crew appreciated the convenience of the innovation. But it turned out to be not ideal - the astronauts get a very long working day, 18-20 hours, of which 11 have to be spent in spacesuits. There was an obvious desire to reduce the time from start to docking even more. But the shorter the flight time, the smaller the allowable phase range. New ballistic tricks came to the rescue - if you allow the launch of the ship into a slightly different inclination orbit, you can additionally maneuver the launch time, expanding the boundaries of the phase range. Already in space, the ship (or the third stage of the launch vehicle) will perform an additional maneuver to the side in order to combine the planes of the orbits, because the docking requires matching (coplanar) planes.
The first attempts were unsuccessful - due to technical problems, the launches of Progress at the end of 2017 and the beginning of 2018 were shifted to reserve days, forcing the use of a two-day backup scheme that had become available. The first “Progress” according to an ultrashort scheme flew last summer and reached the station in 3 hours 40 minutes. And now the second test has successfully passed, in which time was reduced a little more, to 3 hours 21 minutes.
Please note that in the two-turn proximity scheme, the phase range fell to 6 ° (from 12 ° to 18 °). Despite all the tricks, catching a station within the acceptable range is now even more difficult, and successful flights show an increase in the level of control and management of the large and heavy ISS. And this is not the limit - Raphael Farvazovich back in 2013 wantedabout docking in one turn! To do this, you will have to change the area of autonomous rapprochement, but the problem seems to be solved. So, it is quite possible that in a few years the Soyuz will even more look like a suburban Gazelle - “an hour and a half in cramped conditions, and you are on the ISS”. And the technical and mathematical difficulties this short flight provides will be an amazing surprise for the curious, who want to dig deeper.
The launch of the cargo ship, photo CC "South" / Roscosmos
Such different records
A. Sokolov. First experimental space station (docking of Soyuz-4 and -5 spacecraft)
A light historical irony is that the first dockings were just fast. The USSR holds an absolute speed record - on April 15, 1968, an unmanned Soyuz called Cosmos-213 docked with the Cosmos-212 of the same type only 47 minutes after launch. A record manned docking could also become Soviet - Soyuz-3, which was piloted by George Beregovoi, became close to the unmanned Soyuz-2 in less than an hour. But, alas, on the night side of the orbit, the astronaut was unable to correctly orient the ship, and the dock broke. So the record for the speed of manned docking belongs to the Americans. Launched in September 1966, the Gemini 11 docked with the Agen target after 1 hour 34 minutes.
Now such records cannot be surpassed, and the reason lies in orbital mechanics. In the USSR, there were two launch sites at the Baikonur cosmodrome, and the first ship could be put into orbit, which would pass over the cosmodrome a day later. At this moment, the second ship started, which immediately appeared near the first. For the first time, such a trick was turned with the Vostoks -3 and -4, and the cosmonauts Nikolaev and Popovich were at a distance of line of sight from each other. In the United States east of the spaceport there was an ocean, which allowed launching the second ship in the same orbit as the first, twice a day - in the ascending and descending section of the orbit. In any case, the launched second ship turned out to be at a distance of several kilometers from the target and could immediately proceed to dock.
Salyut-7 station and the Soyuz docked ship
When the operation of orbital stations began, these schemes stopped working due to the fact that the stations were launched into higher orbits, slowed down over time, and the Soviet also maneuvered independently. As a result, the USSR and the USA went different ways. In the USA, flights to the Skylab station took 6 turns or 8.5 hours. In the USSR, they switched to a daily regimen. The station performed the maneuver, preparing its orbit to receive the ship, which flew for about 24 hours. When the Mir orbital complex was launched in the mid-80s, it was too heavy for a special maneuver, so the ships switched to a two-day approach scheme. This was also influenced by another factor - as practice has shown, a day after the launch, the astronauts were keenly adapting to zero gravity, they felt worse and if necessary, switching to manual docking functioned less efficiently and made mistakes. A two-day docking scheme began to be used on the ISS, and before the beginning of the tenth years, cargo and manned spacecraft reached the station in 34 turns.
Speed and precision
By the beginning of the tenth years, the transition to digital control systems on ships and launch vehicles allowed us to begin experiments with faster docking schemes. At RSC Energia, Rafail Farvazovich Murtazin, who has been working in the ballistics department since 1979 and now occupies the position of head of the department, has become the main enthusiast.
R.F. Murtazin, photo by Vera Tyukalova / “Your space sector”
But how long should I go? History has shown that the daily regimen is not optimal. In general, according to doctors and astronauts, the acute period of adaptation to zero gravity begins after about six hours in space. The second limitation was set by the technician - after the fifth orbit, the orbit shifts relative to ground-based measuring points, and it becomes much more difficult to control the ship. Initially, a five-turn scheme was developed, but it turned out that, due to the control features, it cannot be pre-tested on a cargo ship. So, it was precisely four turns or six hours that became the maximum permissible for a short circuit. Moreover, the methodology should be working constantly, a record for the record does not make sense. And for this it was necessary to learn how to solve technical and ballistic problems. The ISS is the heaviest station that has ever existed, and the possibilities for maneuvering it to form the required orbit are very limited. It is also large, with huge solar panels, and is noticeably inhibited by the remains of the atmosphere. And the density of these residues depends on solar activity, which cannot be predicted months in advance. In addition, sometimes you have to perform maneuvers to avoid space debris. There are also technical limitations - docking must be done on the day side of the orbit and in the visibility range of ground control points. Well, finally, you need to keep the orbit parameters compatible with future launches. And the density of these residues depends on solar activity, which cannot be predicted months in advance. In addition, sometimes you have to perform maneuvers to avoid space debris. There are also technical limitations - docking must be done on the day side of the orbit and in the visibility range of ground control points. Well, finally, you need to keep the orbit parameters compatible with future launches. And the density of these residues depends on solar activity, which cannot be predicted months in advance. In addition, sometimes you have to perform maneuvers to avoid space debris. There are also technical limitations - docking must be done on the day side of the orbit and in the visibility range of ground control points. Well, finally, you need to keep the orbit parameters compatible with future launches.
The main parameter that determines the possibility of docking is the phase angle and its allowable range. When the Soyuz or Progress is separated from the third stage of the launch vehicle, they are in low orbit at an altitude of approximately 210 km. The ISS flies higher at 400-450 km. To fly to the station, the ship needs to raise its orbit and aim at the point where the station will be after a while. Therefore, at the time of separation between the ship and the station there is a so-called phase angle (in the figure there is a bright sector).
The phase angle has a valid phase range. For a two-day scheme, it was just huge - 150 °. And in the four-turn circuit, it turned out to be much smaller - 22 degrees (phase angle from 18 ° to 40 °). And then it was necessary to apply technical tricks, for example, the ship performs the first two maneuvers in standalone mode, relying on the calculated, rather than the actual position. In subsequent maneuvers, when the withdrawal error became known, a correction was performed. Without this trick, the phase range would have fallen to about 15 degrees, and it would have been extremely difficult to stack an unevenly and unpredictably decreasing station.
Maneuvers and orbit altitude of the Soyuz MS-11 spacecraft, source
The limit of excellence
The first manned "Soyuz" went to the station according to a short scheme in 2013, and the crew appreciated the convenience of the innovation. But it turned out to be not ideal - the astronauts get a very long working day, 18-20 hours, of which 11 have to be spent in spacesuits. There was an obvious desire to reduce the time from start to docking even more. But the shorter the flight time, the smaller the allowable phase range. New ballistic tricks came to the rescue - if you allow the launch of the ship into a slightly different inclination orbit, you can additionally maneuver the launch time, expanding the boundaries of the phase range. Already in space, the ship (or the third stage of the launch vehicle) will perform an additional maneuver to the side in order to combine the planes of the orbits, because the docking requires matching (coplanar) planes.
The first attempts were unsuccessful - due to technical problems, the launches of Progress at the end of 2017 and the beginning of 2018 were shifted to reserve days, forcing the use of a two-day backup scheme that had become available. The first “Progress” according to an ultrashort scheme flew last summer and reached the station in 3 hours 40 minutes. And now the second test has successfully passed, in which time was reduced a little more, to 3 hours 21 minutes.
Please note that in the two-turn proximity scheme, the phase range fell to 6 ° (from 12 ° to 18 °). Despite all the tricks, catching a station within the acceptable range is now even more difficult, and successful flights show an increase in the level of control and management of the large and heavy ISS. And this is not the limit - Raphael Farvazovich back in 2013 wantedabout docking in one turn! To do this, you will have to change the area of autonomous rapprochement, but the problem seems to be solved. So, it is quite possible that in a few years the Soyuz will even more look like a suburban Gazelle - “an hour and a half in cramped conditions, and you are on the ISS”. And the technical and mathematical difficulties this short flight provides will be an amazing surprise for the curious, who want to dig deeper.