To be read after Lesson 12

The Space Age

Russia was the first nation into space and is recognized as the world's leader in building space stations and conducting long-duration space missions. Since Yury Gagarin's epic flight Russian space science and engineering have come a long way. Space technology remains Russia's deepest source of pride (гордость). Russia has launched a great number of space vehicles designed to perform a variety of functions. Unmanned satellites have been of great significance in the exploration and peaceful use of outer space. They help us learn more about the relations between processes occurring on the sun and near the earth and study the structure of the upper atmosphere. These satellites are provided with scientific equipment for space navigation of civil aviation and ships, as well as exploration of the World Ocean, the earth's surface and its natural resources.

In April 1971, history's first space station, Salyut 1, was launched and over the next 15 years six its subsequent versions operated in space. Many orbital manned flights were performed

aboard these stations involving a lot of cosmonauts, most of them having flown several times. Russian cosmonauts are known to hold the record for the longest time in space (L. Kizim has worked 375 days) and for continuous stay in space (V. Titov and M. Manarov — 365 days, i.e. a year). The knowledge of Russian doctors and researchers about the medical and psychological consequences of longterm space flight far exceed that of American scientists. In 1973, two years after Salyut 1, the United States launched Skylab, the Western World's first space station which was used for three highly successful missions. All these manned missions paved the way for even longer stays aboard the Russian Mir space station and, then, aboard the International Space Station.

The most successful Mir space station was launched in February 1986. It was expected to have a lifetime of only five years but it had been in orbit for 15 years before its controlled re-entry into the atmosphere. This space station was equipped with an astronomical observatory module named Kwant. It incorporated all the novelty that could be offered by designers and engineers. To keep productivity high, Russian designers paid much attention to the space station livability. The interior of Mir was painted in two colours to provide the crew with a sense of floor and ceiling. On Mir cosmonauts got two days off each week and had a special radio so that they could talk to their families and with any sportsman, scientist or celebrity they wanted.

With the twin Vega space probes being successfully launched in 1986, Russian scientists conducted close-range studies of Halley's comet and gathered impressive scientific data about Venus. Vega 1 and Vega 2 carrying more than 30 research instruments passed within 10,000 kilometers of the comet's heart, transmitted high-quality pictures to Earth and revealed for the first time the dimensions and dynamics of its ten-mile-long nucleus. The relative speed of approaching the comet was equal to 78 km/sec. It should be pointed out that the study of Halley's comet was conducted on the basis of extensive cooperation of scientists. Scientists from nine countries, including the U.S, joined the Vega project.

When the 170-million horse power launch vehicle called «Energia» was successfully tested in 1987, Russia has gone far ahead of the United States in the space race. With the new multi-purpose Energia rocket it became possible to put into orbit a 100-ton payload (one must know that the first satellite carried 83,6 kg).

The first International Space Station components, Zarya and Unity, have opened a new era of space exploration. The three-stage

Russian Proton booster was used to launch the Zarya module. The rocket was designed by the Salyut Design Bureau and is manufactured by the Khrunichev State Research and Production Space Centre in Moscow. The Proton is among the most reliable heavy-lift launch vehicles in operation with its reliability rating about 98 per cent. Proton measures about 180 feet tall, 24 feet in diameter at its widest point and weighs about 1,540,000 pounds when fully fueled for launch. The engines use nitrogen tetroxide, an oxidizer, and dimethyl hydrazine, a fuel, as propellants. The first stage includes six engines providing about 1.9 million pounds of thrust at launch. Four engines creating 475,000 pounds of thrust power the Proton's second stage. The Proton's third and final stage is powered by a single engine that creates 125,000 pounds of thrust.

Assembling the station will be unprecedented task, turning the Earth orbit into a constantly-changing construction site. More than 100 elements will be joined over the course of 45 assembly flights using the Space Shuttle and two types of Russian rockets. An international team of astronauts and cosmonauts will do much of the work by hand, performing more space works in just five years than have been conducted throughout the history of space flight. They will be assisted by a new generation of robotic arms, hands and perhaps even free-flying robotic «eyes».

The international partners, Canada, Japan, the European Space Agency, are supposed to contribute the following key elements to the ISS: Canada is to provide a robotic arm to be used for assembly and maintenance tasks on the station. The European Space Agency is building a pressurized laboratory to be launched on the Space Shuttle. Japan is building a laboratory module with an attached platform where experiments can be exposed to space as well as logistics transport vehicles.

Scientists believe the ISS to be the most advanced base for developing technologies, systems and procedures to enable safe, efficient and permanent human presence in space.

Cryptography

From e-mail to cellular communications, from secure Web access to digital money, cryptography is an essential part of today's information systems. The only way to protect a message is to encode it with some form of encryption. Data encryption is very important for network security, particularly when sending confidential information. Encryption is the process of encoding data so that unauthorized users can't read it. Decryption is the process of decod-

ing encrypted data transmitted to you. The most common methods of protection are passwords for access control, encryption and decryption systems, and firewalls. Firewall is a software and hardware device that allows limited access to an internal network from the Internet.

Cryptography helps provide accuracy and confidentiality. It can prove your identity or protect your anonymity. It can prevent vandals from changing your Web page and industrial competitors from reading your confidential documents. And in the future, as commerce and communications continue to move to computer networks, cryptography will become more and more vital.

But the cryptography now on the market does not provide the level of security it advertised. Most systems are not designed and implemented together with cryptographers. Present-day computer security is a house of cards; it may stand for now, but it can't last. Electronic vandalism is an increasingly serious problem. Computer vandals take advantage of technologies newer than the system they attack, using techniques the designers never thought of and even invent new mathematics to attack the system with.

No one can guarantee 100 % security. But we can work toward 100 % risk acceptance. Fraud (обман) exists in current commerce systems. Yet these systems are still successful, because the benefits and conveniences are greater than the losses. Some systems are not perfect, but they are often good enough. A good cryptographic system provides a balance between what possible and what is acceptable.

The good news about cryptography is that we already have the algorithms and protocols we need to secure our systems. The bad news is that that was the easy part; implementing the protocols successfully requires considerable expertise. Thus, there is an enormous difference between a mathematic algorithm and its concrete implementation in hardware and software.

Design work is the main support of the science of cryptography and it is very specialized. Cryptography combines several areas of mathematics: number theory, complexity theory, information theory, probability theory, abstract algebra, and formal analysis, among others. Unfortunately, few can do the science properly, and a little knowledge is a dangerous thing: inexperienced cryptographers almost always design imperfect systems. Quality systems use published and well-understood algorithms and protocols. Besides, only when cryptography is designed with careful consideration of users' needs and then integrated, can it protect their systems, resources, and data.

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