"Regulus, report!" shouted Holt into his microphone.
The answer came in a thunderous bang in the intercom and a blinding flash from Regulus' rocket motor, where there should have been a steady jet of smooth flame.
Holt flicked the emergency cutoff switch and Polaris' jet collapsed into silence.
Quietly, the commander spoke into the microphone.
"Polaris to Vega. Take over expedition command. Proceed as planned. Polaris will stand by to help Regulus."
He gazed at the five rocket jets receding into the vastnesses of space as Knight's voice answered, "Roger. Wilco. God keep you. Over. Out."
With a word to the copilot to return Polaris to her original position relative to Regulus,
Holt moved down the central shaft of Polaris' nacelle and entered the airlock leading to the busy bee. He went forth to assess the extent of the damage and to bring what help he could.
As the bee approached the damaged vessel, Holt saw the after flames of the explosion fade and die at the stern of Regulus. He knew from this that the propellant control valves had not suffered and had shut off the flow. The great cylindrical rocket motor itself, however, was completely shattered, together with its tubing, wiring, and other accessories.
He steered his bee into the guide rails of Regulus' nacelle and was greeted by her commander's plump face grinning a bit shamefacedly through the port. Major Freddy Duncan was a calm soul and far less subject to edgy nerves than some of his fellow commanders. With the knowledge that the latter were receding into the distance at many miles per second, Holt rejoiced in his confidence in Duncan's stability. The airlock opened and the visitor entered a bluish haze and heard the hissing of escaping air.
"Splinter punctures?" he asked calmly.
"A few," answered Duncan imperturbably, "but they're all located and we'll have them plugged pronto."
"Anybody hurt?"
"Poor Nordenskjold got a splinter in his right thigh, which smashed his femur. He lost a lot of blood. Our medic's working on him now."
"I hope he's up to the job! Barrett's over a thousand miles away in space by now and we can't call him back!"
Duncan rubbed his cheek. "He's a good boy, but this looks like a large order for his amount of medical training, Colonel. Haven't you got a Martian in Polaris who's supposed to be a surgical whiz?"
"We'll get Svetla on the intercom and see if he can help," said Holt. "In the meantime, let's see how Trygve's feeling…"
Nordenskjold was strapped to the bunk in the captain's cabin, his upper right leg swathed in bandages. As Holt pulled himself into the tiny space Nordenskjold smiled wanly.
"It seems that I'm always making trouble for you, Colonel," he said.
"Don't worry about that, son," answered Holt. "We'll get you out of this all right.
You're needed back on Earth, you know. Not every pilot can make good landings without nose wheels…"
He patted the youth's shoulder, then sent for Royer, the navigator, and retired to the pilot's compartment with him and the captain of Regulus.
Duncan looked quizzically at his commander. "Colonel," he said, "it seems as though we've missed the bus. If we try to install a propulsion system from one of those cargo vessels still floating out there, it will take so long that Earth will be way past the point on her orbit where our voyaging ellipse intercepts it. You can't take us down and introduce us to your friends on Mars because you forgot to bring the wings back with the landing boats. It looks as though we were in the permanent Martian satellite business."
With a smile at Duncan's imperturbable humor, Holt answered, "We can't repair Regulus, but there's still a chance. The mathematical planning section and their electronic brains figure out a solution for just this kind of situation. We'll take a set of tanks from one of the cargo vessels, attach them to Polaris, and fill them with what's left of your Regulus propellants. That will give us a velocity reserve permitting Polaris to make a faster trip back to Earth, even with your Regulus crew aboard. Of course, we'll be down to a bare minimum of food and essentials. Royer, how does it look from the figure standpoint?"
The navigator studies his tables. "There's no time to be lost," said he. "We'll have to be on our way in not more than 104 hours. That's just a little more than four days. If we can tank up with Regulus' full supply, we can pick a returning ellipse which will have a perihelion at a distance of 140 million kilometers from the Sun. That is about nine million kilometers less than the distance of Earth's orbit from the Sun, and this ellipse will intersect Earth's orbit at an angle of 8 degrees and 40 seconds after a voyaging time of 233 days. Fortunately, the Earth will be at that intersection at that time. But if we are to enter such an ellipse, we shall have to give our ship a velocity change of 2.275 kilometers per second when we leave the Martian orbit, as compared to only 2.01 kilometers per second for the other five ships. And when we attempt to reenter our former departure orbit around the Earth, we'll need a velocity change of 4.28 kilometers per second instead of the 3.31 called for by the original calculations. What with the crew of Regulus and the necessary oxygen, food and water, Polaris' load will be increased by 19 tons, and with Regulus' propellants, we'll just be able to make it along the ellipse of which I've spoken. If we add our four days to the 233 days, we can be back near Earth 213 days from now, while the other ships will need 260 days. We can be home 47 days before them, if all goes well."
The four days of grace were hectic and the three available busy bees worked constantly, even through the hours of darkness, when the great mass of Mars shielded the workers from the light and heat-giving rays of the Sun. The three cargo vessels which had been stripped of their landing boats still hung near the lonely Earthlings as they whirled around Mars, and Holt selected the four empty tanks still attached to Goddard as those to be used. They were first towed to Regulus and temporarily suspended from her structure in order to facilitate their filling with the available propellants. Regulus had lost 32 tons through the rips caused by the explosion of her rocket motor, so that only 326 tons were still available for Polaris' desperate venture.
The next problem was to bring the partially filled tanks over to Polaris and to attach them properly. Each of the four was filled to only two-thirds of its capacity, so that it was necessary to top them off with helium under slight pressure in order to distend and facilitate handling. With a busy bee at each tank header, the unwieldy shapes were carefully towed to a position close to Polaris, from which all hands in pressure suits gently inched them into position and bolted their suspension nets to the cruciform tank supports.
When the tanks were attached, the crews connected the aspiration tubes leading to the propellant pumps, and the pressurizing lines. Finally, they adjusted the temperature control blinds and the liquidometers. The last beeloads of food and supplies were loaded into Polaris, the final checks and tests were made, and the engineer reported to Holt that they could depart a scant five hours before the elapse of the critical 104 hour period.
Oberth's High-Duty radio station still swam near them in the velvet darkness, and Holt had kept it manned and in communication with the distant convoy, so that both the departing crews and Earth itself might be kept informed of the desperate struggle for preservation.
The last message announced that Polaris' rocket motor would be started within the hour, and that the laggards would enter a satellite orbit around Earth in 209 days. Until then — silence, for the High-Duty station must be left circling in the Martian orbit along with the remnants of the landing boats and cargo vessels.
Holt touched the prestage ignition switch and waited tensely. A few seconds later the main jet roared its deep-throated song of power. A silent prayer of thanksgiving rose to the lips of all in the crowded nacelle as they felt the familiar thrust. Svetla, their Martian guest and fellow traveler, relayed their belated farewells to his home planet and assured them that Mars, no less than Earth, accompanied them in prayer. Tired but hopeful, they settled themselves against the weary, weightless coast through space.