What The Ionisphere Is Doing For You

FR several months now, a United States military aircraft has been grounded at Nadi, Fiji, due to fire damage. When the accident was re

ported many people probably had their interest stirred for a moment by the announcement that the aircraft had been engaged on ionispheric re

scare h and naturally asked: ‘What is the

ionisphere?”

The ionisphere

consists of a num ber of rather vague layers o f ionised gases en veloping the earth at various dist ances out in space the actual dist ance out varying from day to night,

to season, and under the in nuence of sun spots. station^n d fvr ° f t r , adi 9 reflections by wnrKilfo the Islands > as part of a a sWv l de research organisation, is kn ° Wn even Sri s r l£ !. be possible for tances 4p han lme-of-sight disl he publlc servant at Kavieng, home from work and tun- R^Hin 18 A rec . eiv er to the news from fu Au ! tralla ’ ma y not appre ciate the fact that the signal has been bounced from sky to earth. reaches him" ° nce ’ before » faSng— due ToThe o g f tCt vague, invisible layer, at a point perhaps a hundred miles or so directly above Willis Islet, midway between his receiver and the Vic torian transmitters.

And he might be even more sur prised to know that but for what is going on in a building surrounded

Upper: The Raro tonga ionisphere station. Lower: An observer at work. On right the transmitter and on left the re ceiver with hooded display - tube like a television receiver.

Between them stands the time clock which records in the sealed office next door. The loudspeaker on the left merely provides entertainment be tween duties.

by palms and tropical vegetation a mile or so up a quiet valley on Ra rotonga, his reception might be a lot worse. For the ionisphere measuring station at Rarotonga is the only remaining one in the Islands.

It had been known for many years that long-range short-wave commu nications were governed by the height of the several ionisphere layers, but during World War II it became vital, especially in connec tion with some of the major landing operations in the Pacific and in Europe, to know, in advance, ap proximately what the ionisphenc situation was going to be. The de sign of all the radio equipment, and especially the portable equipment, was dependent on a prior knowledge of what radio frequencies would be best. Those frequencies were gov erned entirely by the height of those mysterious ionised layers.

Thus, there was set up a network of stations all over the world de signed to take hourly or even half hourly measurements of those heights to see whether their rising and falling followed any rhythmic establishment of the South Pacific stations was accom oished in a series of interesting op tions involving the little New Zealand auxiliary vessels New Golden Hind (since sunk in the Tuamotus), Tagua (now owned m Papeete), and Ranui (now engaged on crayfishing in the f^ r of New Zealand). Some of that story

is told in the New Zealand war history pamphlet The Coast Watchers. , The first station was established at Raoul, Kermadecs, in May, 1943; then a station was erected on Campbell Island, away to the south.

Later that same year, a station was set up on Pitcairn, and in Feb ruary of 1945 the Rarotonga station

and one in Fiji came into operation.

The Americans had stations at Christmas Island (later shifted to Palmyra) and Guam, and are still maintaining others at Maui, Adak and Okinawa. Australia at present maintains a station at Macquarie Island. , , .

The Rarotonga station had severa. temporary homes before settling into a new, permanent building ir

mid-1948. It is something of a surprise to come across this “bof finery” in its secluded location up the Takuvaine valley, inland from Avarua. A visit is not only interest ing but also an amusing study of the battle of the conscientious European officer-in-charge with an Island staff whose outlook on life is typically Polynesian. lonispheric measurements must be taken hourly, day and night. Ob viously the European officer cannot maintain supervision throughout the 24 hours, and his .young Maori observers are prone to turn in for the night after he has gone, “cook ing” the records early the following morning on the basis of their ex perience and what they think the readings ought to be. This has lead to a battle of wits. Next to Ihe observing room is an office. In t is a time-recorder which must be ictuated by the observer on duty jressing a lever in the other room -every hour.

The office is locked and every door md window is fitted with burglar tlarms which once set off cannot be topped until the office is unlocked .nd the power cut off. It was found hat even with this arrangement, or omething similar, the Maori ob ervers had devised ways of faking be records over a long period of ime. To-day the system is be eved fool-proof—though a punish lent list of gardening duties for oys who sleep in is displayed on le office notice board!

The equipment consists of a radio •ansmitter which can be tuned, like radio receiver, over a band of fre iencies from 1,700 to 1,8000 kc/s. eside it is a receiver. The trans fer sends pulses of radio waves 3 to the ionisphere. They are re acted back and picked up by the iceiver. As their speed of travel accurately known (about 186,000 lies per second), it is possible to itermine the height of the reflect g layer by measuring the time ken for the return journey.

Instead of the receiver feeding to loudspeaker, as in an ordinary t, it feeds instead to a display tube nilar to that on a television re iver. With the aid of a scale, the ights of the layers—sometimes ree are in evidence—are ac rately given.

Prom the information obtained this and other stations of the w world-wide network, it is now ssible for a central office to pre :t with fair accuracy what the uation will be months ahead rice the announcement from time time made from Radio Australia ind from all other short-wave tions—that seasonal changes of quency will be made so that ;eners everywhere will be pro ied with the best possible signal ength. larotonga takes observations at uarter to every hour. The “sweep” :es 10 minutes to complete. The led results are telegraphed to

New Zealand once each month and from there passed on to a central ofl l C r Was hington, DC, where published predictions are made availabie to the world. Even thl USSR co-operates in this work which serves the communication re

quirements—including propaganda

broadcasts-of all thl world r v \ Dudley Tuti, a Solomon Islands student at St. John’s College Auckland, NZ, was ordained a priest on November 21, at St. Marv’s Cathedral. He is believed to be the first Melanesian ordained a priest “ Jh 0 Cathedral. He left NZ shortly afterwards to take charge of a school in the New Hebrides