March 1 – New Heights

Today’s Factismal: The rockoon (balloon-rocket combination) was created in 1949.

Back in the 1940s, there was a lot of scientific interest in the upper atmosphere. The only problem was that very little was known about it. It was relatively easy to take measurements in the troposphere, which is the lowest part of the atmosphere; just stick up a weather station in the nearest field and you could measure temperature, pressure, wind speed, and all of those other things that make a meteorologist’s day. you could even get measurements for the upper troposphere by sending up a weather balloon carrying an instrument package.

The atmosphere (Image courtesy Kelvinsong)

The atmosphere (Image courtesy Kelvinsong)

But the troposphere is just the start of the atmosphere. Above it is the stratosphere, which behaves very differently from the troposphere. Where the troposphere is unstable both vertically and horizontally, leading to a constant three-dimensional churning and mixing, the stratosphere is relatively stable vertically, which causes the different layers to have distinct chemistry and movement. Today, airplanes regularly cruise through the lower parts of the stratosphere as they ferry passengers and cargo from one part of the world to another. But in 1949, there were very few aircraft capable of reaching it – and none that could reach the upper portions where the most interesting things happened.

Naturally, scientists thought of rockets as a way to bridge the gap in their knowledge. Though rockets would speed through the stratosphere and provide only short snapshots of what was happening, it was still more data than was currently available (i.e., none). But the rockets of 1949 weren’t very good. Though the larger ones could reach the stratosphere (in 1944, one had even gone through the stratosphere and on into space), they were too expensive to fire in the numbers needed to provide meteorologists and atmospheric scientists with the information they wanted. What was needed was an inexpensive way to stretch the range of smaller and cheaper sounding rockets that were then available.

A rockoon on the deck of the USS Colonial (Image courtesy Stratocat)

A rockoon on the deck of the USS Colonial (Image courtesy Stratocat)

James Van Allen came up with the way. By lifting a sounding rocket up into the higher part of the troposphere before “launching” it, the sounding rocket would go well into the stratosphere and provide the data that the scientists wanted. But putting a rocket on a balloon meant that you would have even less control over where the rocket came down than usual. So Van Allen talked to the US Coast Guard and convinced them to test his idea on an icebreaker that was headed to Greenland. He put an Aerobee under a weather balloon and included a remote control to ignite the rocket and send it on into the stratosphere.

The first two launches were failures, which actually told Van Allen and the others something about the state of the upper atmosphere. Because the solid fuel would only ignite above a certain temperature, the upper atmosphere had to be very cold. Scientists had known this from theoretical calculations, but this was the first direct proof. In order to combat the cold and because he was on a very small budget, Van Allen heated up cans of orange juice and placed them next to the firing mechanism before sending the next rockoon up and away. The make-shift fix worked and the rocket fired. Rockoons were a success.

A rockoon launch (Image courtesy Stratocat)

A rockoon launch (Image courtesy Stratocat)

Alas, the success was to be short-lived. Because rockoons had to be launched at sea, the payloads were often lost when they returning rocket sank rendering the flight useless. And increased improvements in the range and accuracy of conventional sounding rockets meant that what had once been unattainable heights were now regular accomplishments. As a result, the rockoon was relegated to an “also ran” status and research into the upper atmosphere and space continued through the channels we now know.

But research into alternative ways to get into space are still continuing. If you’d like to contribute to the effort, then why not join citizens in Space as they try to make the final frontier part of our world?

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