doi:10.19486/j.cnki.11-1936/tj.2017.24.007
With the increasing frequency of China's space launches, as well as the competition for the space launch market by private companies represented by the United States SpaceX company, now the comparison of the number of rocket launches has gradually become a matter of considerable concern on the Internet, in the eyes of many people, the comparison of the number of rocket launches in various countries is like watching a game, and the alternate increase in the number of space launches of China, the United States and Russia represents the comparison of their strength in the aerospace field, so it is very ornamental and representative.
However, what I want to say here is that the number of rocket launches does not mean that there is no meaning at all, and this indicator can still reflect certain trends in the aerospace field of various countries to a certain extent, such as the activity of space activities, which in turn partially reflects the capabilities of the space industry and the needs of military and civil spaceflight. However, this significance should not be exaggerated, and only after conducting a more in-depth analysis and taking into account some factors can we use the number of space launches to roughly assess the situation of world space competition.
Track and quality matter
The first factor we need to pay attention to is that the purpose of rocket launch is to put a certain payload into Earth orbit or deep space, so that these payloads can serve humanity. Therefore, the number of "pieces" of the rocket does not necessarily determine the parameters of the orbit load. One parameter may come to mind at first: quality. The capability of a satellite is directly related to its weight, and no one wants their satellites to be bigger and heavier. Therefore, regardless of the difference in technical level, the heavier the satellite, the heavier the satellite, the more capable it is. Then, it is clear that the number of rocket launches is only one aspect, the weight of the satellite launched by the rocket is even more critical, like India's PLSV rocket for launch, its low-orbit carrying capacity is only about 3 tons, which is only equivalent to the level of China's earlier model of "Long March" 2 rocket, and Russia's 6 8 tons of low-earth orbit launch capacity "Soyuz" rocket compared with the gap is very large, we are now familiar with the American SpaceX company's "Falcon" 9 rocket low-earth orbit carrying capacity has also been from 10 of 1045 tons, 11315 tons, added to 22 of the latest FT model8 tons, and the "Long March" 5 rocket carrying capacity that China is developing and launching has reached 25 tons, obviously these large rockets and those small and medium-sized rockets can open up the gap of orders of magnitude, but the two rockets with different capacities are absolutely equal in the number of launches.
In addition to the quality, there is also the issue of track parameters. When we look at rocket launch reports, we often see low earth orbit (LEO), geosynchronous transfer orbit (GTO), geosynchronous orbit (GEO), etc., which are very different from each other. The low-earth orbit is more than 200 kilometres above the surface, while the geosynchronous transfer orbit is an elliptical orbit with a perigee within 1,000 kilometres from the surface and an apogee 36,000 kilometres above the ground. Obviously, the launch capability of the geosynchronous transfer orbit is not really the "into orbit" payload capacity, because the satellite has to consume a lot of its own fuel and reduce its weight to reach the final target orbit. However, the performance column of many rockets can only write geosynchronous transfer orbit, because the ability to send satellites directly to geosynchronous orbit is not available to every rocket, and it is not what general customers need. But the military users are different, and many of its large, sophisticated and confidential satellites have strict requirements for speed, stability and weight in orbit, so those rockets with diamond diamonds are needed to take over the porcelain work. For example, the United States' "Delta" 4 heavy rocket, on the one hand, uses three universal core stages and is equipped with a powerful RS-68 liquid hydrogen liquid oxygen engine, on the other hand, it has multiple ignition capabilities, so it can directly send the top secret heavy spy satellite of the United States to geosynchronous orbit, and the mass of geosynchronous orbit into orbit can reach 675 tons, this is a very strong capability, you must know that if this rocket sends the payload to geosynchronous transfer orbit, its carrying capacity can reach 14 tons, as for the lower low earth orbit, its carrying capacity limit can reach 28 tons.
Of course, in addition to these orbits, there are also orbits like sun-synchronous orbit (SSO), launch into lunar orbit and launch into Martian orbit. For example, the Long March 2E developed by China focuses on low-Earth orbit, while the Long March 3B focuses on geosynchronous transfer orbit. There is a close relationship between the difference in orbit and the capabilities of satellites, for example, photographic reconnaissance satellites need to have lower orbits, which is easy to understand, and the lower the orbits, the clearer they can see. Of course, it can't be too low, the lower the orbit, the closer it is to the upper edge of the atmosphere, the greater the drag, and the faster the orbit loses altitude. Communications satellites and early warning satellites prefer geosynchronous orbits, of course, if they need to take into account the Arctic region, they will choose large elliptical orbits, and some electronic reconnaissance satellites will also choose such high orbits.
The performance of the load is critical
Since about 1966, the number of space launches of the Soviet Union began to rapidly surpass that of the United States, and even reached the United States many times. During the Cold War, the Soviet Union even maintained hundreds of rocket launches per year for the purpose of deploying various military satellites, but it is not difficult to find that the Soviet Union never had any advantage in maintaining the number of military satellites in orbit at the same time. Why is this, did all the rockets that the Soviet Union shot into the sky drill into a black hole?For example, in 1985, the Soviet Union sent 33 photographic reconnaissance satellites, but the lifespan of these reconnaissance satellites was only a few weeks, that is, as long as this kind of launch activity stopped for a month, there were basically no Soviet photographic reconnaissance satellites in the earth's orbit. Naturally, the Soviets could only launch into the sky one after another. In contrast, during the Cold War, the United States generally launched heavy spy satellites such as "keyholes" that carried a large amount of fuel and could work in orbit for several years or even more than 10 years, so when one country launched a satellite in orbit within one year and worked in orbit for 10 years, and another country launched 20 satellites with a lifespan of three weeks for 10 years in a row, there was actually no big difference in the actual use effect. Of course, the example of the Cold War period is a little extreme, but the basic logic is not difficult to understand, and there is another extreme example in contemporary times, that is, nano satellites, India has now done dozens of satellites with one arrow more than once, naturally no one will think that India is the leader in the field of world satellites, and the kind of "potato satellites" that can be made by college students by hand cannot replace real large satellites in terms of capabilities.
Therefore, if anyone wants to evaluate the space activities of various countries through space launch missions, instead of simply counting the number of rockets, they may wish to evaluate from other angles.
First of all, it is important to note whether these launches are only international commercial launches or national payload launches. It is common for a rocket launch to cost tens of millions to $100 million, while a satellite can easily cost hundreds of millions of dollars. Therefore, even from the perspective of output value, who made the payload in a launch mission is actually more important than who built the rocket that launched it. The significance of China's use of the Long March-3 rocket to launch a home-developed remote sensing satellite is obviously far greater than that of the European company Ariane's use of the Ariane-5 rocket to launch a communications satellite purchased from the United States by an international operator.
Next, let's see which rocket it is. If we take the Russian "Soyuz" rocket as a reference, the launch cost of heavier rockets such as "Delta" 4, "Proton", "Long March" 5, "Ariana" 5, etc. will be relatively expensive, and the payload they carry will either be military, or have important value in civilian applications or scientific research. And those rockets with a low-Earth orbit transport capacity of only 2 3 tons or less, such as India's PLSV, the American "Minoto", China's "Long March" 2A, B and C, and other models, obviously need to be multiplied by a coefficient of less than 1. Of course, this is only a rough assessment, and it is not intended to be absolute.
Then the last thing to pay attention to is the technical level and value of the launched payload itself. The Saturn probe known as Cassini is planned to cost more than $3 billion and weigh 64 tons, to be sent to Saturn, more than a billion kilometers away, so it depends on one of the most powerful rockets at the time, "Hercules" 4 launch, and the "Curiosity" Mars rover program cost 2.5 billion US dollars, with the "Cosmos" 5 rocket launch, and the use of 4 solid boosters of the 541 thrust configuration to launch. As for the satellites of the United States, such as large reconnaissance satellites and early warning satellites, they all embody huge amounts of investment and cutting-edge technology, and they are generally hundreds of millions to more than a billion dollars.
As far as civilian use is concerned, the first is the cargo spacecraft that provides supplies for the International Space Station, and this task is in charge of the "Dragon" spacecraft and the "Cygnus" spacecraft of the American SpaceX company, and the manned delivery mission is temporarily handled by the Russian "Soyuz" spacecraft. The second is NASA's deep space probes, such as the "Horizon" Pluto probe launched in 2006, as well as various civil communication satellites, meteorological satellites, scientific research satellites, etc. The payloads of the military and intelligence agencies mainly include early warning satellites, optical reconnaissance satellites, electronic reconnaissance satellites, GPS navigation satellites, and military communications satellites.
About the launch success rate
Chinese are proud of the success rate of China's rocket launches, and Chinese astronauts have done a really good job in this regard. It is worth noting, however, that after more than half a century of exploration and practice, the success rate of the main launch vehicles of the major space technology competitors is basically very good.
First of all, the reliability of the "Cosmic God" and "Delta" series of the main carrier rockets of the United States is quite high, with more than 100 successful launches in a row, and the reliability is almost 100 percent. Of course, this is also an achievement under the strong demand of the United States and other departments, after all, their satellites are often billions or even billions of dollars, and it is unbearable to bomb them once. As for the new rising star SpaceX's results are not bad, so far in more than 40 launches, except for one in the air**, one is mostly successful, a small part of the failure (the loss of a secondary load, and the main load "Dragon" spacecraft and the International Space Station successfully docked), the others have been successful, this success rate is also more than 96%, even if the ground test and not the launch ** is counted, its success rate is close to 94%, not low.
Let's talk about Japanese rockets. In fact, since Japan began in 1999 and has been almost 20 years now, its H-2A and H-2B rockets have been launched more than 30 times in a row, and only once have failed, with a success rate of about 97%, which is really not low. Some people may be obsessed with recalling the two H-2 rockets 20 years ago, and intend to rely on it to continue to be happy for decades, but if you really want to ** the technical problem itself, Lao Huang Li is indeed going to lose it, and facing the opponent is the real self-confidence.
In contrast, Russia's rocket launches are in a state of superficial goodness but hidden danger. Because now its space launch is mainly supported by the decades-old and gold-medal rocket "Alliance". Speaking of which, this "Soyuz" rocket is indeed a legend, and its record may not be broken for a long time, because by now, it has sent more than 1,000 rockets, with a total success rate of nearly 97%, so it is also very reassuring that one of its submodels was used to launch the "Soyuz" manned spacecraft to support the International Space Station. However, in addition to the "Soyuz" rocket that supports this scene, Russia also has a "Proton" rocket that launches heavy payloads, and the reliability of this model is not so reassuring, and in recent years it has almost stabilized at the level of one bomb per ten shots, which is obviously not satisfactory.
And Europe is also doing very well, its main rocket "Ariane" 5 encountered some problems in the early launch, including the first test launch in 1996 exploded, but then gradually got on the right track, as of the beginning of 2016, it has created a good record of 70 consecutive successful launches. In general, the technology is also very mature, but with SpaceX vying for international commercial launch contracts, Europe will face considerable pressure.
From the above, it is not difficult for us to find some basic rules about rocket launches, first of all, the long-term use of old rockets can be relatively easy to achieve a stable and high success rate, Russia's "Union" Rockets are a typical example, there were not many failures in its early launch history, but a rocket that persists in hundreds of launches over the decades, and learns lessons from them, and continues to improve and optimize various problems that arise, if this does not finally enter a very mature stable state, then it is really wrong. The same is true of China's "Long March" rocket, which was first born out of the "Dongfeng" intercontinental missile, and the "Long March" 2 rocket with a strong shadow of the intercontinental missile was later derived from the "Long March" 3, "Long March" 4 and other series of rockets, that is to say, from the "Long March" 1 to the "Long March" 4, the technical context of the entire rocket lineage is a relationship of continuous evolution on the basis of a foundation. For example, after the early model solves the technical problems of the first and second sub-stages of the rocket, the subsequent models can reduce the probability of problems in this part. Therefore, we will find that the failure of China's launch vehicles is also relatively early on, especially in the era of "Storm" rockets and "Long March" 1, counting all these rockets that have been developed and launched, the success rate is 9211%, which is about 91% of the more than 5,000 launches worldwide since 1957. And if you don't count the "Storm" and other rockets, just count the "Long March" series of rockets, which have been launched more than 250 times, and the success rate is 94About 4%. This success rate can be said to be very good, and it is basically the same as the gold medal rocket series of the United States and Russia, all on the same level, such as the "Delta" series of rockets in the United States has been launched more than 300 times so far, with a success rate of about 95%.
Comparing the problems that have occurred in the history of the "Long March" rocket, it can be found that if a certain submodel has few changes, the success rate may be higher, and if the new submodel has relatively large changes and new technologies are adopted, the probability of accidents may be higher, such as the "Long March" 3B and "Long March" 5 are all problems that occurred in the early stage after the development of their models and the start of the launch mission. Again, this is an easy to understand pattern. Just as the "Ariana" 5 exploded on the first shot, but in the end it became a gold medal rocket that fired 70 rounds in a row, and the "Long March" 5 had one or two problems that could not be overcome.
It is precisely because space launch activities have high requirements for reliability, and it is difficult for such a complex and sophisticated system of rockets to achieve this, so astronauts from various countries have taken a steady line in technology, Russia has relied on the "Soyuz" and "Proton" two old rockets for decades, and China has been using the "Long March series" until recently switched to the new "Long March series". In contrast, the United States is the most radical in the world's aerospace industry in order to maintain its leading position in space technology: In the early 60s of the 20 th century, it developed the "Red Stone" rocket, the "Hercules" rocket and other emergency rockets, and then developed the "Saturn" 1b and "Saturn" 5 rockets to complete the manned landing on the moon, and then in the 80s of the 20 th century, it fully switched to relying on the space shuttle to operate low-earth orbit payload launches, and then continued to develop the "Hercules" series, "Delta" series and "Cosmos" series of rockets. After the end of the Cold War, especially in the past 20 years, the "national team" of the United States aerospace represented by NASA and ULA has gradually tended to be conservative, but now after allowing private space to enter, there are SpaceX's "Falcon" series rockets, orbital science's "Antares" rockets, etc., it can be said that there are constantly new rocket series in research, launch, and use, and each new series may bring about a high accident rate in the early stage, such as the "Falcon" 1 rocket fired three times and exploded, "Antares" The rocket was launched not very often, but in 2014 it also blew up a Cygnus spacecraft. In the history of rocket launches in the world, the overall launch success rate of the United States is relatively average, inferior to that of Russia and China. But as mentioned earlier, this is mainly due to two reasons, one is that after the Soviet Union launched its first satellite in 1957, the United States rushed to develop a large number of immature rockets and payloads in the late 50s and early 60s of the 20th century for the sake of the space race. However, this is only reflected in the overall launch record, and it is another picture when it comes to different rocket series, such as the success rate of its main space payload launch missions, such as the "Delta" series and the "Cosmic God" series, which are very high.
But now the new problem is that after SpaceX's "catfish" to stir up the situation, this stable state cannot last forever, as mentioned earlier, ULA has a near-perfect launch record, but now both NASA and the military have begun to hand over some launch tasks to SpaceX. And judging from the current trend, whether it is the ULA of the United States, the "Proton" and "Soyuz" of Russia, or the "Ariana" of Europe, orders for its space launch missions are flowing to SpaceX. The trend is accelerating as the number of launches the company has begun to skyrocket this year. In the future, it may lead to such a Matthew effect, that is, if the order drops too much, whether it is a Russian or EU rocket, the launch frequency will decrease, and this will lead to a high cost of a single launch after the maintenance cost is amortized, which will lead to further loss of orders. In the next few years, the international space launch market will undergo tremendous changes. This is actually forcing companies in various countries to start a round of chasing new technologies, and the long-term silence has gradually been broken.
ULA is now developing a new generation of "Vulcan" rockets that can be ** engines, replacing the "Delta" and "Cosmic God" with a very high success rate, which is obviously forced to reduce the pressure of costs. Russia is also developing and perfecting the "Angara" rocket in the face of a shortage of resources, and Europe is also planning a new generation of rockets. However, as things stand, these measures alone are not enough to deal with competition from private companies such as SpaceX and Future Blue Source. With the "Falcon" 9 rocket into the annual mass launch, its reliability will also be like the "Soyuz" rocket precipitation at a fairly high level, low cost and high reliability will make SpaceX a low-cost rapid launch payload service provider, space launch cost reduction has become a foreseeable future picture, competitors around the world need to make their own responses. It should be mentioned that in this new situation, China's situation is more favorable than that of Europe and Russia. Because of China's huge size and strong internal civilian and military demand, China did not rely on international launch business in the past, so the impact on China from new private companies to seize orders in the international market is very small. Therefore, the new generation of rockets represented by the "Long March" 5 is a new starting point, and the world space competition after the reshuffle of the new era will be more exciting.