Ballooning around the world

Aeronauts call circumnavigating the world in a balloon “the Last Great Adventure.” One attempt ended in the Pacific Ocean on December 26, but other balloonists are raring to go–eight expeditions in all.

The most technologically advanced balloon ever to make the attempt, sponsored by Re/Max, may have already been launched by the time you read this, and could even now be riding high-altitude winds at the very edge of space, almost 40 kilometres high.

There are three main types of manned balloons. Hot-air balloons use propane or kerosene burners to keep the air in the envelope heated and thus less dense than the surrounding air. Helium balloons are filled with a lighter-than-air gas, and rely on ballast to regulate their altitude. Roziere balloons combine the two approaches: they’re use helium and heat it with burners, so they need less ballast.

Typically, balloons are limited to an altitude of about 12 kilometres by the tropopause, the upper boundary of the troposphere, the atmosphere’s lowest region. As you climb through the troposphere, the temperature falls about six degrees Celsius per kilometre. The tropopause is a distinct layer of extremely cold air, -85 to -100 degrees Celsius. Cold air cools hot air and helium alike, causing both to become more dense and lose lift, which in turn causes the balloon to sink down into warmer air, where the cooled gas produces even less lift. To counteract these effects, balloons have to constantly burn fuel or drop ballast. When they run out of either, down they come.

Team Re/Max however, is using a type of NASA research balloon with enormous lifting capability–at its daytime altitude, it will be138 metres in diameter and 210 metres tall (large enough to envelope the Houston Astrodome) and will contain 1.13 million cubic metres of helium. It should punch through the tropopause into the much warmer stratosphere. At 40 kilometres, the thin air is about -25 Celsius; at night, the balloon will sink down to about 25 kilometres, into colder air–where the helium will actually provide more lift, preventing further descent. As a result, Team Re/Max should use relatively little ballast.

Of course, flying in the stratosphere presents its own challenges. At 40 kilometres, the atmospheric pressure is only .004 that of sea level. To protect its two-man crew, the gondola, a welded aluminum cylinder 2.4 metres in diameter and about two metres tall, must be built much like a space capsule. For example, it’s painted with a special white paint to protect it from the fierce solar radiation, which could heat the gondola’s skin to 90 degrees Celsius (falling at night to -70!). Tanks of liquid nitrogen and oxygen provide air; solar panels provide electricity. Emergency equipment includes a parachute for the entire gondola and pressure suits and parachutes for each crew member. Scientific instruments to study atmospheric phenomena and test a new method of tracking ocean storms, plus photographic equipment, communications equipment, food, water and ballast, make up the rest of the payload.

Team Re/Max has been waiting for good weather so it can launch from Alice Springs, Australia. One advantage of flying in the southern hemisphere is that the team won’t have to fly over several countries that object, such as Russia, Iraq and especially China. The biggest challenge is likely to be landing. No one has ever landed a balloon of this sort or size. The plan is to release helium to lower the balloon into the troposphere, then use ballast to control the rate of descent. If all goes well, the team should return to Australia 18 or 19 days after launch.

If , despite its technological innovations, Team Re/Max can’t pull of the first balloon circumnavigation, plenty of others are waiting to take up the challenge. Cable & Wireless, the largest modified Roziere balloon ever made, hopes to fly soon from southern Spain. Breitling Orbiter 3 is awaiting launch in Bern, Switzerland. World Quest, piloted by Dick Rutan, who made the first (and so far only) non-stop, unrefueled airplane flight around the world in 1986, plans to launch from Santiago, Chile, in July. Spirit of Peace is getting ready in Albuquerque, New Mexico. J. Renee, the only solo-piloted balloon, is awaiting launch outside Chicago. Finally, Global Conqueror will launch from either Alexander Bay or Beaufort-West, South Africa, between June and August.

The challenges are immense, but it seems that 1999 may very well be the year the “the Last Great Adventure” is finally achieved.

Keep watching the skies!

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