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Balloon Launch Part 1
 On our 5th Triumphal Tour of Australia (TToA/5), we were lucky enough to see the launch of a scientific balloon. Now I'm not talking about something the size of a large car - but instead, something one quarter of kilometre in diameter! Even though these balloons can carry a payload of some 3 tonnes to an altitude around 125,000 feet (38 kilometres) above the ground, their skin is only as thick as the cling wrap you use in the fridge! On this particular TToA/5, we were testing a Toyota Landcruiser Turbo Diesel MultiValve - the family way, with two adults and three kids. We had traversed the Strzelecki Desert and the Sturt Stony Desert by ourselves, crossed the Simpson Desert with the Australian Head of NASA (Ted Ankrum), and then headed by ourselves up to Alice Springs. Ted had very kindly arranged permission for us to attend the launch of one of these gigantic balloons.
By a coincidence, when we were some 100 or so kilometres out of Alice Springs, we could see, glinting in the afternoon Sun, a large white blob in the sky. To the naked eye, it was roughly as big as the Moon. This was one of the enormous balloons that we had come to see. Because it was so big and so high, it was visible all the way into Alice.
Unfortunately this balloon, a few days later, sprung a leak. It couldn't reach its desired altitude, and so the crew controlling the balloon had to abort the mission. The launch crew blamed this leak to a sudden single gust that happened during the launch. This gust was not very powerful, but because the balloon was so big, the wind was able to spin the balloon about its vertical axis. The balloon, of course, had spun back again, but the launch crew had suspected that in that rather sudden twist, a few small tears had appeared in the incredibly thin, gossamer-like, membrane of the balloon.
 These balloons are enormous - about 250 metres in diameter. But the wall is very thin - about 0.15 mm thick, which is roughly the same thickness as cling wrap. Hanging immediately beneath the balloon, and attached to it by steel cables, is a parachute. Hanging underneath the parachute, also connected by steel cables, is a gondola. Right at the end of the mission, an explosive charge separates the parachute from the balloon, and the parachute and the gondola float peacefully down to the ground. This gondola carries the payload, which seems to be a word invented in the 20th century.
In 1991, Aviation Week and Space Technology (which some journos call Megadeath Weekly) celebrated its 75th anniversary. In their anniversary special issue, they showed a few old-time advertisements, and one in particular caught my eye. This ad was first published on March 23, 1922. It read, "Why pay the excessive prices some Aircraft Manufacturers are asking for their machines, if you can get an up-to-date "FOKKER" at half the money?" And then the ad described what you got for your money - a "Fokker-Limousine-F 111 with 360 H.P. "Rolls-Royce" Engine". And then under the picture of the plane were these magic words that caught my eye - "Paying Load 800 Kg".
Nowadays, the word "payload" is a single word, and it means "that part of the aircraft's load from which revenue is derived". In other words, it's the load that you can charge for - whether that load is mail, freight, or passengers. But back then, when the airplane was young, payload was two words - "paying load".
Now the English language is a living vibrant language, and it's always changing. Some time after 1922, "Paying Load" turned into "payload". Just as an aside, do you ever wonder what words you use today will be obsolete in 20 years time?
Getting back to the balloon, the gondola hanging underneath these gigantic balloons always carries some kind of payload.
This payload is some kind of telescope. The telescope will usually be sensitive to one of the many types of radiation that is normally blocked by our atmosphere - such as infrared radiation, gamma rays, or X-rays. That's the reason that they try to get the telescope above practically all of the atmosphere.
You might wonder why scientists would bother with a balloon that stays up for only a few days, when a satellite can send back scientific data for years.
Balloons actually have a few advantages over satellites. First, they are a lot cheaper than a satellite. A satellite can cost up to $100 million, and the launch can cost another $100 million. Second, a satellite has an enormously long lead time. This can sometimes mean that the latest, and more sensitive, scientific instruments will just sit uselessly on the ground, while the satellite orbits overhead with 10-year-old instruments on it. But a scientist can design and build a better instrument, and within a few months, launch it on a balloon. Third, sometimes a satellite is in the wrong orbit to look at something in the sky, and in most cases, you simply can't change the orbit. But you can take a balloon to several launch sites around the world, and pop it up, in just a month-or-so.
These balloons are usually launched, in Australia, every few years or so, usually around the end of October. At that time of the year, the wind currents are fairly kind to the balloon during the launch phase. There are three separate teams involved in the mission of one of these balloons. There's a launch crew to actually get the balloon up into the air without it being damaged, a tracking crew to follow its location during the cruise phase, and a scientific crew to run the instruments on board. Each balloon costs $70,000, and once they have begun to unwrap it, they can't put it back into its special covering. The balloon is filled with some $40,000 worth of helium gas. The helium gas comes from America, as a liquid, in giant insulated vacuum flasks. It's allowed to bubble into a gas, and then it's stored in some 40-or-so enormous cylinders that fill up the backs of two, very large, semi-trailers. An average gondola, which carries the telescope, cost about $100,000. This price does not include the price of the wages necessary to build and then operate the experiment in the gondola.
Next time, I'll tell you how we actually got to see a balloon launch.....
Copyright © Karl S. Kruszelnicki
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