'They'd better be right as well as optimistic,' Don grumbled. 'Thanks, Sparks, you - the entire crew - have done a great job on this.'
'Hope it works, sir,' he said, putting down the paper and turning away.
The machines took over. The computer on Mars had worked out the firing instructions for the course change, and the figures were fed into the ships computer. Once it knew the correct attitude desired, the computer fired the positioning jet and tilted the great ship in space. Don looked out the port as stars moved to new positions and smiled wryly, remembering the hours of watching and working he had done to do the same job badly.
Then the waiting began. The needles on the control board moved as the computer ran up the output of the atomic engines in preparation for the firing of the jets. Finger-chewing minutes passed until the computer decided that the correct moment had arrived. It did not inform them that it was time. The first that they knew was when the jets fired and a sudden, sideways thrust pushed at them.
'Well, that's it then,' Don said. 'How soon before we know if we are on the correct course, Dr Ugalde?'
The mathematician frowned in thought. 'I would say that it will be an hour at least before a meaningful base line can be established. We will make observations for Mars Central, and as soon as their computer has established our new orbit we will be informed.'
Telephone, Captain,' Kurikka said, and Don switched on the instrument before him. Rama Kusum's worried face looked out at him.
'Could you come to the sick bay, sir? There is a patient here with a fever and, well, I don't know quite what to do.'
'Any other symptoms?'
'Nothing I can put my finger on, just a generally sick feeling, upset stomach, you know.'
'I certainly do - and there is nothing to worry about. There are any number of mild infections that start that way. Just hold on and I'll come right up to have a look.'
It was almost a relief to have a medical matter to worry about, rather than the responsibility for the entire spaceship. He was a trained doctor and he knew that he could handle anything that occurred. Only in the operation of the ship did he have a feeling of futility.
'I'll be in the sick bay, Chief. Call me as soon as there are any reports.'
He opened the door and was almost run down by Hansen, the air tender. He was hurrying and looked frightened.
'I'm sorry, sir,' he said. 'I was coming to see you. In private, if I could.'
Don closed the door behind him and glanced both ways. The corridor was empty.
'Right here is fine. What is it?'
'The oxygen, Captain, the rate of production has fallen off again. We are way below the replacement rate, and right now people are breathing the stored oxygen in the atmosphere of the ship. I'm taking out the excess carbon dioxide all right, so there is no build-up of concentration of that. But the oxygen... 'How long before the effect will be noticeable?'
'It's noticeable right now! If you were to run around you would be out of breath mighty quick. And soon, two or three days...'
'Yes?'
'People are going to start dying, sir.'
'No localized pain, Mr Preece?' Don asked. He touched the man's neck and his armpits. There was no swelling of the lymph nodes that would indicate a major infection.
'No, and if there were I would tell you quickly enough Preece had a lean face and a hawk-like nose, and was obviously used to having his orders obeyed. 'I paid a lot of money for this trip and it hasn't been much of a holiday so far. Meteors, miserable food, my luggage stolen. Now this. If you ran a clean ship I wouldn't have caught anything.'
'All spaceships have to be hospital clean, to prevent the spread of disease from planet to planet.' The man's temperature was over 100, but his pulse and breathing were normal. 'The chances are that you brought this infection with you from Earth. After an incubation period it has made its presence known.'
'What is it?' He sounded worried now.
'Nothing major, we can be sure of that. So far it's just a fever and nothing else. I'm going to ask you to stay here in the sick bay for a few days, mostly to protect the other passengers. Well give you some drugs to knock out the bug and some antipyretics to bring the fever down. You don't have anything to be concerned about.'
The phone rang while Don was filling the hypodermic, and he almost dropped it in his haste to answer.
'Captain here.'
'We've done it!' It was Kurikka, his normal reserve cracked by the sudden change of events. 'Mars reports that our orbit is now right on the button, or so close that a minor correction will take care of it. Since the reaction mass was so short they have put us into a capture orbit, instead of a normal braking orbit.'
'What is the difference?'
'Normally we head towards the spot where Phobos Station will be, and brake until we match orbits. But we have no mass left for braking. So we are aimed at Mars. Not close enough to hit the atmosphere, but still close enough in so that we'll be captured by their gravity field and will swing back into an orbit around the planet.'
'This is very good news, Chief. Give my thanks to everyone for helping us do the job the right way.'
'Everything will be in the green now.'
Don cut the connection and memory returned. Everything was not in the green. It wouldn't do them much good to arrive safely in an orbit around Mars if they were all dead of suffocation at the time.
He gave the injections and started up the stairs to C deck where air technology control was located. This entire deck was given up to the ships operations and supplies, and rang like a tomb now. He passed empty storerooms - even their doors had been removed - and the places where surplus machinery had been ripped from the deck. Hansen was waiting for him.
'Here are the charts, sir,' he said. 'You can see for yourself.'
Don looked at the pages and the rows of figures blurred as fatigue pulled at him. He handed them back.
'I would rather not see for myself. You're the specialist and I'm going to ask you to explain just what is going on here. What, basically, is causing the drop in oxygen level?'
Hansen pointed at the apparatus on one wall. An illuminated inspection port showed an almost transparent, green liquid.
'It's the phytoplankton, you can see them there, in the port. They are one-celled plants that float in water. When they receive the carbon dioxide we breathe out in the ship they convert it back into oxygen. We lost too many of them when the water was lost during the accident. And a lot more died or mutated during the solar storm. There are not enough left to produce the amount of oxygen we need.'
'Is there any chance of growing more?'
Hansen shook his head. I'm doing my best to weed out the mutant strains and encourage cell division and growth. But it's too slow. There is plenty of nutrient to be added to the water, but the rate of division can't be accelerated.'
I can appreciate that.' Don looked around at the other machinery in the large compartment. 'What is the rest of this apparatus?'
'Mostly water processing, testing, microscopic analysis, automated monitor system and that kind of thing. Over there is the raw air processing. Filters to take out contaminants, and the carbon dioxide reducer.'
'Doesn't that help?'
'Some, but not enough. I have it going flat out now. It breaks the carbon dioxide back down into carbon and oxygen all right, but it was just designed to take up the slack in the main system. Sort of fill in when there is an excess of CO2 for limited periods.'
Don tried to prod his tired brain.
'We have stored oxygen. Won't that help?'
'Negative, sir. Only for a limited time. The total stored oxygen is less than enough for a twelve-hour period for everyone on the ship.'
Then what can we do?'