Elaborate instrumentation replaced the war head of the atomic missile. This radioed its determinations back to the ships circling the planet.
The telemetering technique employed was in no way novel, for it had long before been used in reverse in rocket instrument vehicles which explored the mysteries of the upper atmosphere on Earth.
Holt transferred his flag temporarily to the Ziolkowsky in order to be present at the launching of the first of the three bombs from her launching mount. The latter was a simple affair of steel sections with two interior guide rails; two feet in diameter and some twenty long, the bomb lay ready between them. In order not to endanger the ship by the jet of the bomb, the mount was attached longitudinally to an out-jutting member of the tank retainer, and was some ten feet clear of the ship. Being parallel with the keel of the vessel, it could be directed much as the stern torpedo tubes of a submarine are directed by swinging the whole craft.
John Wiegand and Lussigny, with the help of some of the technical ratings, had spent the last 24 hours calibrating and inspecting the complicated instrumentation and the telemetering gear which would radio back the data. Aside from the relatively simple problems of securing and sending simple readings such as pressure, temperature, humidity and instantaneous altitude as found by electric altimeter, the bomb was also equipped to analyze automatically the composition of the Martian atmosphere and to transmit it by radio.
As John Wiegand often remarked, "Measuring is no great trick! But to measure correctly… Ay, there's the rub!"
A busy bee moored to Ziolokowsky served as launching station. Lussigny's High-Duty radio set aboard the Ziolkowsky was still in reserve and was equipped with a special receiver for the bomb's telemeter transmitter, together with the oscillographs which would record the vital data. Wiegand in the busy bee was to attend to the firing, with Holt as an interested but inactive spectator, while Lussigny sat before his automatic receiver and Haynes, in the control room of Ziolkowsky, would lay the vessel to the correct angularity.
All three parties were in permanent contact via the ship's interphone.
John Wiegand spoke into his microphone. "Attitude set?"
"Attitude set!" came Haynes' voice.
"Receiver tuned?"
"Receiver tuned!" said Lussigny
"Ready on the firing line: FIRE!"
Flame shot from the tail of the bomb, urging it rapidly out of the mount. Like a torpedo, steered by its small gyros, the sounding bomb passes close to Aldebaran and Polaris. The flame contracted to nothingness after four seconds, for the bomb's speed had been reduced to 130 m/sec less than the 3.14 km/sec with which Ziolkowsky was circling Mars.
After nearly an hour, one half its time to circle Mars, the bomb would reach the atmosphere tangentially at the lowest point of its ellipse. Then it would dive deeper and begin to take its measurements and to send them back to the anxiously waiting Mars crews.
Tensely the men waited. Every ten seconds a signal impulse flitted across Lussigny's check instrument, showing that the telemeter transmitter in the bomb was "alive" and at the ready. At the sixtieth minute, the multiple indicators on his receiver came to life, proving that the instrumentation of the bomb had armed itself faithfully.
Lussigny switched on the oscillographs which would record the many readings radioed by the precipitously falling transmitter in the bomb. Slowly the light-sensitive strips of paper wound themselves through the recording instruments. From the tracings which would later appear would come the final word whether the design of the landing boats had been based upon solid facts, or whether guesswork had made a landing on the long-sought planet too risky.
Now the tiny specks of light on the instruments began to register, for the bomb had entered the atmosphere and was beginning to telegraph the vital information. For twenty drawn-out minutes the luminous points danced across the observation screen. Then they suddenly vanished. The bomb had reached Martian ground!
Hardly had the light specks disappeared than Lussigny feverishly began to develop the paper strips. Twenty-four hours later Holt addressed his anxious crews by radio to tell them that he proposed to take the landing boat of the Oberth down to Mars within three days, with Glen Hubbard as pilot.
Chapter 21 — Down to Mars
Tom Knight took over the command of the vessels circling Mars with strict injunctions not to risk any foolhardy efforts with other landing boats until Holt so ordered by radio from the surface. Should he crash in the attempt, Knight was to keep the space vessels in the satellitic orbit until a suitable opposition for a return should occur between Mars and the Earth, employing his time with such observations as might be made from the orbit.
A series of eight radio relay bombs was then fired off into the Martian atmosphere after the manner of the sounding bomb. The radio relay bombs contained automatic transmitters and receivers which could receive short waves from the circling space vessels and retransmit them on long wave. They could also receive long waves and retransmit them as short waves. The object of these devices was to permit constant communication between the landing party and the circling convoy, for a line-of-sight between the two would exist for only very short stretches at a time, due to the rotation around Mars of the space ships. Such line-of-sight is essential to short wave communication. But Lussigny had predicated his design of the radio relay bombs on a Martian ionosphere which would reflect long waves and permit radio communication between any points upon the surface.
Thus several radio relay bombs would always react to long wave signals from the landing party, while one or more of them would always be in line-of-sight with the convoy.
After they had been eased to ground by their parachutes, Lussigny "questioned" them as to their readiness and no less than six responded, to his great delight. He reported to Holt that uninterrupted two-way communication was assured when the latter should have made his landing.
John Wiegand and his inspectors went busily to work on the Oberth's landing boat, seeking not only defects in its involved mechanism, but subjecting the three caterpillars, the respirators, the pressure suits, the radio, and even the food and water supply to the most exacting scrutiny.
"The devil," said John, "is a squirrel. Wouldn't it be silly to go through all this and have one of the boys die on Mars of ptomaine poisoning?"
Eighteen composed the first landing party and Holt was unwilling to shift the burden of its leadership to anyone. Glen Hubbard, his executive and pilot, had vast experience as former Chief Test Pilot of United Spacecraft in supersonic glides and landing techniques of experimental craft. No other captain could compare with him.
Dr. Gudunek, the linguist, was a member, in the hope that he would be able to initiate conversations with the Martians, whose intelligence was by now a foregone conclusion.
Sam Woolf's geological knowledge would be of inestimable value in getting out of the polar melting zone and in finding a suitable area in which to lay out landing strips for the wheeled landing boats. John H. Billingsley's experience with strange races and peoples Holt thought might be extremely important. As engineer, there was First Sergeant Clark E. Winslow, whose tireless efforts had kept the Oberth in Wiegand's good graces throughout the trip. Harry Brooks was radio man, and Lieutenant Hempstead, with a detail of 10 soldiers, was there to do odd jobs, including the operation of the caterpillars and their radio sets. These men would also undertake the building of landing strips, once the equatorial zone had been reached, or, if need be, hold off any unhoped-for Martian attacks with tank ordnance and small arms.