Southtrap

I stood silent and eyed them. Accompanied by Wegger, tough and bare-chested, we must have looked as if we meant business.

Smit laughed uncomfortably and cracked his knuckles.

'Why not practise with the buoy itself instead of a man?' I asked.

Bokkie was lashed to a couple of eyebolts on the floor nearby.

Smith crossed to the orange-headed drifter and ran his hand affectionately down its centre tubing.

'We can't risk this PVC tubing — it's the weak point about Bokkie. I'd rather have had fibre-glass but it couldn't be moulded in time.'

Holdgate had regained his feet and his dignity. 'I offered to deputize for Bokkie,' he said.

'Are you telling me there are weak points in a buoy which is going to hit some of the wildest weather in the world in the West Wind Drift?' I said to Smit.

Smit rushed to his own and Bokkie's defence with a spate of technical talk.

'She's not weak for that. It's okay when she's floating. But she isn't meant to be stood up and extra weight put on the long body. We're re-testing every component again now. We scrapped the French barometers because they drifted too much. The British type are fine, except that they eat current, don't they Pete?'

Pete, a bull-necked young man with a growing-time of only two days on his beard since he embarked, said in a deep voice, 'Bokkie's now got one of the new Yank-model barometers. They cost less, use less power.'

Smit stroked Bokkie's lower limb, inside which was the power pack. 'These batteries have got to last a year. A whole year!'

T-shirt Jannie broke in. 'I remade the antenna myself before we started off. The old one was up to maggots…'

'Wait,' I interrupted. 'There's something I want to ask you about the buoy. But first of all, did any of you see anyone suspicious around here this morning?'

'There was an old bag with a cigarette-holder,' answered Jannie. 'She was suspicious of everything. Mostly of us. Wanted us to promise we wouldn't photograph the penguins or something.'

'Or something,' echoed Smit.

'Good,' I replied. That's that, then. Now, about the buoy.'

Smit was like a skua hen defending a chick. 'What about the buoy?'

The radio's gone sour on us. I reckon we're running into a full-scale radio black-out. Ionospheric storm.'

'So what?'

Holdgate wandered away uninterestedly to his own instruments.

'Well, won't that affect Bokkie?' I asked. 'What about the automatic signals to the satellite?'

'It makes no difference,' replied Smit. 'It's a line-of-sight transmission.'

'I don't follow.'

He regarded me a if I'd been a spastic case. 'The Tiros N satellite was fired into polar orbit specially for the Global Atmospheric Research Programme. Tiros will make four passes a day over the area where Bokkie and the balloon operate after we've set 'em going on Monday. Clear?'

I nodded and he went on. 'Tiros is equipped with what we call a Random Access Monitoring System — RAMS for short. It picks up the signals from the buoy and the balloon.'

'All the buoys and balloons,' Jannie corrected him. 'It's a global-scale experiment. Bokkie's only a part of it. But a very important part. The Southern Ocean's a tough proposition, as you know. That's why it's so important that nothing should stop us launching the buoy on Monday morning…'

Ten sharp, GMT,' Smit added.

'On the dot,' echoed bull-neck Pete.

'You still haven't answered my question,' I persisted. 'As I see it, the whole project could misfire if the ionospheric storm goes on. In my experience they usually last four or five days. That means Monday may be blacked out. Also, I don't understand how the satellite can distinguish whether it's Bokkie or our balloon signalling when there are others scattered about the oceans of the world.'

Wegger shifted his feet. Duty forced him to stay and listen.

'Each buoy or balloon transmits signals with a specific frequency at short intervals,' Smit explained. The series of signals in each transmission is the method of identifying the buoy or balloon as well as giving the various readings of pressure, temperature and so on. The transmission consists first of a ten-bit data word used for barometric pressure, word two is an optional parameter, and word three must be eight bits showing surface water temperature…'

I cut in. 'Skip it. I simply don't know what you're talking about, man. Just tell me in one-syllable words why the radio black-out won't affect signals from the buoy to the satellite.'

He thought for a moment, wrestling with the problem of getting down to my kindergarten level.

Finally he said, 'This is how it goes. The buoy is floating in the ocean — right? The satellite appears over the curve of the horizon — four times a day it does that. Right? as soon as it does, it picks up the buoy's signals because the buoy and the satellite are now seeing each other — line of sight, it's called. Right? The process is not like ordinary short-wave radio signals which bounce off the high layer of the upper atmosphere. It's more like pointing a gun — while the buoy and the satellite are in sight of one another, the signals get through. It's like your ship's radio-telephone — you could speak on the R/T to another ship during a full-scale black-out providing you were close enough.'

'Are you telling me that, in spite of the radio blackout, I could have a ship-to-ship conversation on the R/T? It's a new one on me. I'd like to have tried it, but it so happens that there's never been another ship around on such occasions.'

'Of course it would depend on the distance between the ships.'

'How far would that be?'

'It's not easy to estimate — an outside limit of four hundred to five hundred kilometres, I'd say. Of course the quality of voice would deteriorate considerably, but it might still be bearable. Other factors come into it to, like the strength of the signals.'

T-shirt Jannie added, 'As the satellite orbits the earth, it picks up masses of information from all the other buoys and balloons. This is recorded on magnetic tape, and then — it's really very smart — the satellite "dumps" all the information to the receiving station at the National Center for Atmospheric Research at Boulder, in the United States. Boy, you should see their computer! It digests all the information, and works out every buoy's exact position…'

'It sounds like black magic,' I interrupted. 'I wish it were as easy for me to calculate my ship's position. How does it work?'

'When the satellite approaches Bokkie or leaves her behind, the frequency of the signals varies all the time,' he explained. 'From these varying frequencies the exact position can be computed. And it really is exact — down to less than half a kilometre in a very wide ocean.'

I said, 'I'm beginning to get the measure of Bokkie's importance in the chain.'

Smit said, 'We've checked and re-checked the electronics package. We'll re-check finally tomorrow, just to make sure. But it's all systems go for Monday morning.'

I could sense that Wegger was growing more restive, but I persisted with my questions. 'I can see that the whole project is a miracle of planning but what if something goes wrong? What happens, say, if Bokkie's transmitter packs up when she's been only a few days on her own?'

Smit frowned. 'It can't — it mustn't. If the data parameters show something wrong…'

'One-syllable words please!'

He grinned. 'If Bokkie suddenly starts giving information on sea temperature or barometric pressure which is haywire, an alert goes out. Likewise, if her rate of drift went wild…'

'How could anyone know? Anything can happen in these seas.'

'No, it can't, Captain. The buoys which were set adrift last year as a pilot experiment showed that the fastest drift speed we can expect from a buoy is about one knot. The biggest distance she will cover is slightly under fifty nautical miles a day. An alert would go out if it was suddenly much different from that. We can pinpoint Bokkie's position precisely four times a day, like I said.'