Vengeance 10

‘Basically it does, providing that such gravitational force is not overcome by one even stronger. Many people reading Professor Oberth’s book made that mistake.’

‘And how do you make certain that does not happen?’ There was a trace of annoyance in Heydrich’s voice. Clearly, Bethwig thought, he does not like being talked down to.

‘It is a matter of acceleration or speed,’ Bethwig broke in before Wernher could make matters worse. Heydrich had surprised him by showing genuine interest in the details of the project.

‘The correct speed must be selected to place the craft into the proper orbit. Too slow a speed will cause it to fall back to Earth. Too fast, and it will fall into the sun. Even faster, and it will escape the solar system altogether.’

‘Correct,’ von Braun broke in. ‘As the spacecraft approaches the moon, our observations become more accurate, allowing the speed to be adjusted. The occultation — disappearance of selected stars — behind the moon enables us to determine the exact course of the rocket as it approaches for a landing.’

In spite of the veiled threats of that evening three weeks before, Heydrich had since been polite and considerate, had even invited them to Hradcany Castle, his Prague headquarters, for a weekend. With brilliant autumn sunshine streaming across the pleasant garden beyond the french doors, Bethwig could feel tired muscles and tense nerves relaxing. That morning he and von Braun had strolled around Prague, and the mood of the city had certainly suggested that Heydrich was the model administrator he claimed to be. Bethwig recalled his comment about benevolence versus destructiveness. People seemed content, well fed and dressed, and there was none of the sullenness one encountered in Belgium, France, or even Denmark. The Czechs seemed to have adapted well enough to National Socialist rule — or Heydrich had adapted it to them.

Von Braun had begun to describe the rocket. ‘We have determined that a single-stage rocket, a vehicle designed to complete a mission as a single unit, is not practical. It would be far too large, given our present fuels, and cause insurmountable aerodynamic problems. So we have designed a three-stage vehicle, that is to say, three complete rocket vehicles stacked one atop the other. The first rocket, or stage, is the most powerful, as it must lift the combined weights of the others. Once its fuel is exhausted, it will be jettisoned, and the second stage will drive the rocket into space and temporary orbit around the Earth. Then, when it’s in the right position, the second stage will fire one last time, sending the third stage on its way to the moon. This final stage will coast along its assigned trajectory, firing its engines only to make course corrections and to brake itself to a landing on the moon. The rocket must then be refuelled from supplies brought up by drone rockets before it can return to Earth.’

Heydrich had leaned forward to listen. ‘You find it necessary to build three separate rockets? I thought the guiding principle in engineering was to make things as simple as possible. It would seem that the use of three rockets would increase the chance of failure thrice over.’

‘Actually, nine times, Herr Heydrich. But, as Franz said, we have not the fuels to build a rocket that can reach the moon in a single stage. In fact, even with three stages it will barely be sufficient. We must cut everything to the bone to save weight. Our navigational equipment, for instance, will be of the most primitive — a simple sextant. The smallest possible radio-direction-finding set will be used. And the pilot must be able to fix anything that goes wrong, as we cannot afford the mass to carry a spare set.’

‘Is it a matter of more money?’ Heydrich was smiling as he asked the question, but he was watching the young scientist closely.

‘No. Rather a matter of technology. Our fuel experts have been able to find only one or two fuel combinations that are more efficient than the alcohol and liquid oxygen mixture we now use, and they have drawbacks that negate their value.’

‘I am not certain I understand what you mean.’