the object covered more than forty astronomical units in less than 24 hours. Let me explain, for the non-specialists in the hall. This requires a speed of almost a quarter the speed of light. Since the effects of relativity are already beginning to appear at such speeds, we classify them as sub-light speeds.
"We have analysed the flight trajectory and, on this basis, we have every reason to believe that the object is capable of more. For comparison, our best space engines cannot give us even a hundredth part of such a speed.
"The second aspect is the object's flight through the atmosphere of Saturn. It is obvious that this was how the object performed its braking manoeuvre. I must admit that it is quite an elegant solution. I am confident that our pilots would be glad to do the same, if they had the same shell strength. Let me explain in more detail.
"A spacecraft, like any other physical body in motion, possesses kinetic energy. If you want to carry out a braking manoeuvre, you must relieve the craft of part of this energy. On Earth, whether on land or in an aircraft, this is simple. In the first case you are moving along the ground, in the second in atmospheric air, the force of friction against which can be used as something to hold on to. There is no such possibility in space. Out there, there is nothing to hold on to. Therefore spacecraft are forced to carry with them at least a double reserve of energy, for acceleration and deceleration. In fact, to save fuel, spacecraft often use the gravitational fields of planets to change their flight trajectory, but we can ignore this for a number of reasons.
"But all the intruder had to do was to fly past Saturn, plunge into its atmosphere for an instant, and by holding onto it, disperse part of its kinetic energy. This is a very elegant solution from a technical point of view, but unfortunately it is not available to us with the technology we have now.
"We have made assessment calculations, and it turned out that the braking energy was so great that in the energy dispersal process, the intensity of the effect on the shell of the object was comparable to the energy of a nuclear explosion - equivalent to 500 to a thousand tons of TNT. This is a monstrous load for a craft the size of the intruder. For comparison, it would only take a few kilograms of TNT to damage the shell of our spacecrafts. So we have a difference in strength of the order of five, in other words of one with five zeros.
"Our engineers had a heated discussion about the interpretation of this fact. I don't want to go into details of properties of materials, but there are several opposing opinions. I shall only express one point of view, which is a sort of common denominator - technology of this level will not be available to us for at least another three to five centuries.
"To sum up, it would be most logical to assume that the incomers are ahead of Earth's technology by at least several hundred years. We shall talk later about the consequences of this state of affairs.
"Let us return to the present situation. At this moment, the object is radiating electromagnetic pulses of a specific character, directed towards our terrestrial and space receivers. Our crew of specialists interprets these signals as an invitation to make contact. Up to now, we have not responded to this invitation. We plan to do so tomorrow morning."
General MacQueen made a discreet sign. Shelby nodded in reply.
"I should like to mention one important detail. All the passenger and transport routes passing within a short distance of Jupiter are now being diverted to reserve trajectories by the Flight Control Centre. By morning, there will be no traffic in the vicinity of Jupiter. It is strictly forbidden to approach the object or even the planet in whose orbit it is located. There is an order to open fire on anyone breaking this ban. This applies to all craft of any kind, including trackers.
"As you will have realised by now, the project is secret. To prevent leaks of information, you are forbidden from this moment to contact anyone outside this military base. Due to the current situation, our civil rights are restricted until the president specifically orders otherwise."
On hearing this, the audience in the hall buzzed with indignation. A grey-haired elderly man in the front row stood up and indicated that he wished to speak. Shelby nodded.
At that moment, a small drone with a camera rose up from somewhere behind the stage and flew rapidly towards the man. Stopping smoothly half a metre from his face, with the blades of its small propellers whirring softly, the drone patiently waited for him to start speaking.
"Mr. Shelby, I do not wish to appear impolite, but I, like many others in this hall, am a citizen of another country. So restrictions imposed by your president... I think you understand what I am trying to say," the elderly man said politely. The image of his indignant face was relayed by the drone to one of the reserve screens.
The murmur in the hall, this time of approval, became even louder.
"Silence please, ladies and gentlemen. I understand your resentment. But you must agree that this is a really unique situation. Please show some understanding of this fact. All these bans and inconveniences apply equally to me too. As for the foreign citizens among us, this question has been agreed with your governments. Let us concentrate on the main issue, and leave the concerns of everyday life outside our discussion. As scientists, I think we all understand the motives for this decision."
It was amazing how quickly the indignant fuss quietened down. Some still showed their discontent, but nevertheless, the general mood was constructive. Shelby came out from behind the lectern and, with his hands behind his back, began to walk about the platform.
"So, we know that the object is a spacecraft from a non-terrestrial civilisation. But we do not know if there are living representatives of this civilisation, or civilisations, aboard it. It is quite possible that the apparatus is fulfilling an automatic programme, and we shall have to communicate with an artificial intellect. This could complicate things, but more on that later.
"The problems we have to solve are these. Firstly, we have to formulate a common communication protocol. In other words, we have to learn how to encode our information so that the object understands it. We need some common language.
"Let us assume that we want to communicate to the object what meaning we attach to the word 'star'. The first thing is to work out how the object, when it has received our signal, will read the word 'star' into it. The next step is to convey to the object the semantics which we associate with the sense of this word."
"You said that the object is sending us signals. What have we managed to read from the messages sent?" called someone from the depths of the hall.
"In our opinion, the object's message does not contain any significant information. It is simply an invitation to a dialogue. Later, I shall give everyone a dossier on the project containing all the information we possess at the moment. You will find the technical details there," replied Shelby.
"How do you want to reply?" asked one of the biologists.
"The most natural thing would be to reproduce the signal exactly. The information scientists among us would call this an echo. The series of pulses lasts a little over two seconds, the pause between each series is about five seconds. We believe that by these five seconds, the object is implying that it is awaiting a reply."
"Assume the object ignores the echo. Then what do we do?"
The question was asked by one of the mathematicians.
"We repeat the echo."
"Assume the object continues to ignore it?"
Shelby made a dismissive gesture, "Let us solve problems as they arise."
The asker nodded approvingly and sat down.
"What will our next step be?" Shelby continued. "Assume that we have made first contact, i.e. we have communicated to the object that we are aware of its presence and that it is clear to us that it is of non-terrestrial origin. What can we say to it, and more importantly, how do we say it?"
"I propose we start with a greeting."
This reply came from a tall man, one of the historians.
"Hmm, yes, a greeting... And what selection of pulses, in your opinion, would co
nstitute a greeting for a non-terrestrial intelligence?" asked Shelby.
Clive looked at Steve and rolled his eyes towards the ceiling. Oh, these humanitarians! Steve smiled slightly in reply.
"Well, what about the greeting that we use between our own spacecraft?"
"Are you proposing to use something like the Morse code, or do you have in mind the algorithms used in modern digital communication?" asked Shelby.
"Er, I'm not sure that a non-terrestrial intelligence would know the Morse code. Open text would probably be better, wouldn't it?" asked the historian.
"Without going into details, digital communication uses something like the Morse code, but thousands of times more complex. For example, before the moment when you manage to hear the greeting, your computer and that of your opposite number have already exchanged a series of pulses. The problem with such a long greeting is that firstly, it makes the task of its interpretation much more difficult, and secondly, the more information there is, the greater the chance that it will be misinterpreted. For understandable reasons, we want to minimise this risk," said Shelby, and made a sign towards the back of the hall.
One of those present stood up and in a well-modulated voice, with much gesturing, began:
"We should not forget that we are subconsciously relying on our experience of human communication. But in this case, we are trying to communicate with an alien race. The difference is that two members of the species homo sapiens, even if they speak different languages, have a certain number of behavioural patterns which are instinctively understandable to them. But in the case of the object, you can't rely on this. Therefore I propose rejecting the idea of a greeting, instead aiming to operate exclusively in universal natural concepts."
Shelby looked into the hall looking for a response to this suggestion. Someone on the right asked for permission to speak. Shelby nodded.
"Thank you," said someone in a deep bass voice. "Sullivan, Professor of Cybernetics. I would like to change the course of our discussion somewhat. We have very little time, and I doubt if we shall be able to work out an effective protocol for the exchange of information.
"Let us not forget that in this situation, we are the more stupid side, compared to our uninvited guests. That is the first point. The second is that we don't know what they know about us. It is quite possible that they investigated us long ago and came to understand the principles of operation of our entire communication infrastructure. When I say infrastructure, I don't only mean electronic channels of communication, but also our speech. Addressing the military in this hall, I would assume that even our cryptography would not constitute a serious obstacle for them. It is more likely that we shall find it difficult to conceal anything from them than to convey the sense of our message to them."
Having heard him out, Shelby asked:
"How exactly do you propose that we begin our 'conversation', if we can call it that?"
"Why, just as you proposed yourself, with an echo. That will be our first reaction to the object's signal. By reacting, we make it known that we are able to receive its messages and reproduce them. The point is that by repeating the signal, we are also giving the object an opportunity to assess the level of development of our apparatus, in particular its resolution capacity."
"Please explain what you have in mind," said the officer sitting next to MacQueen.
Sullivan turned towards where the General was sitting.
"Firstly, the signal has a carrier wave. It radiates electromagnetic waves at a certain frequency, and receives a response signal from us with a certain degree of error. The extent of the error will indicate the accuracy of our instruments, and consequently the level of our
The Contact Episode One Page 9
