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New stage of Space Exploration
(By Yuri Scherbakov) AIR magazine No 5 (May, 2001)
Usually the word combination "Space Exploration" associates with large cosmodromes, work of mass collectives and multi-million expenses. However, now many facts testify that this association can change essentially: in future a spacecraft launch will be considered similar to a long-range aircraft flight in present.
Reasons for such change have been accumulated step-by-step for last 10 - 15 years. The most important reason is great progress in electronics, which allows designing so light and compact apparatus that seemed science fiction in 60 - 70th - Gold Epoch of Space Flights. Besides this, new apparatus appears to be relatively cheep, even small and not rich organizations have finance possibility to order it.
However, progress in electronics has not responded on market of space services. Launching orbiters is still executed with the help of large carriers, and the cost of a kilogram of useful load is rather high. But the main problem is orbital injection of small loads. In this case delivery of apparatus is possible only together with commercial load with the help of large space platform. Besides problems of mutual noise of apparatus, this scheme of delivery is not operative: it is necessary to book space for apparatus on the space platform long before the planning launch.
Besides this, in many cases there is no need in long-term orbit flight, a flight on ballistic trajectory is enough. In last years there have appeared many tasks concerning short-term lifting of apparatus up to 100 - 400 km altitude with the aim of providing emergency communication or aerophotopictures of the ground surface, for example, in case of global emergency or debacle.
All the above has led to facilitating activity in many countries of the world that is aimed to design of a simple, safe and cheep system capable to carry small useful load (up to 20 kg) to a space high ballistic trajectory or even to a low orbit. This activity is stimulated by number of private funds and enterprises, however, basing upon some indirect data, one can see that in certain cases these enterprises are supervised by leading aerospace corporations, which would not like to miss this promising market segment.
Many projects apply relatively simple and cheep solid fuel missiles or hybrid engine missiles, which are mostly supposed to be launched from aerostat.
Selection of the aerostat scheme of launch has been made not by chance. As the main mass of air concentrates in the low layer of atmosphere (thus, the layer up to 10 km contains 75% of air mass), location of a start point at 10 -20 km above surface allows considerable reducing of aerodynamic loss. This is especially essential for a simple solid fuel rocket - its engine operates only few seconds and launching from surface results in high loss because of higher speed for passing through low layer of atmosphere.
Taking into account hard limitation on start weight for rockets manufactured by small enterprises, the economies from high-altitude start are rather considerable.
Interest in this new branch in space exploration arises in our country – one of leaders in space exploration. Russian Aeronautic Society has developed the project concerning the flight of a rocket along a ballistic trajectory. This project planes to use fully the advantage of aerostat start.
As against foreign projects, which are to use a gas aerostat, this project suppose to use a calorific aerostat that provides an air start of rocket of 200 – 300 kg from 10 – 15 km altitude. This option provides easier return of aerostat to surface, considerably simplifying its storing and operation and increasing safety. Also against foreign projects the aerostat is supposed to be piloting that will rise reliability and allow providing high accuracy and landing safety after the first start. The aerostat crew includes a pilot and a start operator.
The general scheme of launch is the following: the calorific aerostat with the rocket and equipment is delivered to the certain point with the help of automobile, railway of air transport. At this point the gondola and starting equipment are join to it, the shell is filled with heated air. After air heating the complex rises up to the boundary between troposphere and stratosphere (10 – 12 km) in 1 – 1,5 hours. At this altitude the last testing of complex’s systems is carried out with the following start of the rocket. As a result the facilitated aerostat gets great lifting force, but the pilot decreases the air heating, and ascent turns to smooth descent that prolongs for some hours.
Completing the planned flight the head part of the rocket drops down with the help of parachute as well as the start stage. This scheme allows avoiding treat for people and buildings and does not use a special landing zone. It also simplifies organizing of the launch.
Implementation of technical part of this project is rather simple. Today the maximum altitude for the AX-12 sport calorific aerostat of 9 000 - 12 000 cubic meters volume is 16,8 km, and for AX-12 of 22 000 cubic meter volume is 19,8 km.
We are going to use the N-850 sport calorific aerostat of 25 000 cubic meter volume, which is capable to deliver the rocket in start container to the 10 – 15 km altitude.
Carrier for the ballistic flight can be designed on the base of the serial military of civil rocket. Today the most appropriate are products of Tula Instrumental Design Bureau and its private subsidiaries.
Increasing of lift altitude because of the aerostat start is about 100%. For example, calculation of altitude for the new generation DU95Y6 two-stage meteorological rocket, which is manufactured by the same enterprise, shows:
Start from surface – 102 km
Start from 10 km - 210 km.
This calculation is made for 80 degree to horizon direction of start.
The optimal option for start is the DU14F6 geophysical rocket of 70 kg start weight, which is capable to reach 180 km altitude in surface launch. Its high ballistic characteristics give opportunity to further applying of this rocket and design of serial product on its base. The rocket has deployable fins, which give opportunity of launch with the help of compact ID and a light launch container.
In future we hope to design more perfect systems intended for injection of light sputniks (up to 20 kg) to low orbits. Selected technical decisions allow expecting high economic efficiency of this complex.