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All Aboard the Space Elevator

By Dave Reneke

Dave Reneke brings news from the space and astronomy communities around the world.

All Aboard the Space Elevator

Imagine this! A cable, 50,000 km long, anchored below the ocean to an orbiting space platform that allows cargo, and even people, to climb up. Sounds incredible doesn’t it, but it is possible. In fact, it’s being built now! It’s called a “space elevator” and it’s an idea that’s really out of this world!

There will be no blast of rocket fire and smoke, and no lift-off G forces: just step on the elevator and press the “up” button and step off 8 days later at a platform thousands of kilometres in outer space. The elevator can travel at 200 km/h and could be what space agencies are looking for – safe access to space at low cost.

Space elevators offer a cheaper, safer form of space travel that eventually could be used to carry explorers to the planets. It could reduce the costs of putting payloads into orbit from around the present US$40,000/kg to less than US$250/kg. Quite a saving! Around 94% of the weight of a conventional rocket consists of fuel and other expendable infrastructure.

The space elevator concept is not new. It was proposed years ago but quietly shelved, except for word that reached renowned author Arthur C. Clarke’s inventive ear. His book, The Fountains of Paradise, reinserted the cable concept into the scientific community and made the public aware of the potentials of space elevators.

To take the space elevator from science fiction to science fact, scientists needed a very strong, flexible cable that is long enough to reach from our planet to a satellite. They found what is needed in the form of carbon nanotubes – rolls of sheet graphite that are light and flexible yet 100 times stronger than steel.

The cable would be about 1 metre wide and thinner than a piece of paper but capable of supporting a payload of up to

13 tonnes! It would be held up by the Earth’s rotation in the same way that the string of a yo-yo remains taut when you swing it around your head.

Are there challenges? You bet: radiation, lightning, wind, meteors and space debris, but these are issues that can be dealt with.

Arthur C. Clarke was once asked when people would build a space elevator. “Fifty years after they stop laughing,” he replied. Well, now they’ve stopped laughing.

A Really Cool Star
There’s a new candidate for the coldest known star, a brown dwarf with about the same temperature as a hot cup of coffee. That’s cool enough to begin crossing the blurry line between small cold stars and big hot planets.

Brown dwarfs, a term coined by SETI astronomer Jill Tarter in 1975, are objects that have a size between that of a giant planet like Jupiter and that of a small star. In fact, most astronomers would classify any object with between 15 times the mass of Jupiter and 75 times the mass of Jupiter to be a brown dwarf.

Given that range of masses, these objects would not have been able to sustain the fusion of hydrogen like a regular star, so many scientists have dubbed brown dwarfs as “failed stars”. Brown dwarfs are too cool to give off much visible light but they do emit substantial amounts of infrared radiation.

The newly discovered brown dwarf is identified as CFBDSIR 1458+10B – a catalogued number for the smaller and dimmer member of a binary brown dwarf system located just 75 light years from Earth.

The linked pair were discovered by astronomers at the Keck Observatory on the summit of Mauna Kea in Hawaii, using what astronomers call “adaptive optics”. This revolutionary new method of astronomical imaging essentially cancels out much of the Earth’s atmospheric interference, resulting in much clearer, cleaner telescopic images than ever thought possible.

The CFBDSIR 1458+10 system was originally announced last year, but it was believed to be only a single object. “We were very excited originally to see this object had such a low temperature, but we never guessed that it would turn out to be a binary star and have an even more interesting, even colder companion,” said Philippe Delorme of the University of Grenoble, one of the co-discoverers of the object.

Can life exist on planets around these cool stars? Probably, if the planet has a close in orbit that keeps its surface warm and allows liquid water to exist. Astronomers are planning to observe CFBDSIR 1458+10B in the future to begin mapping the binary’s orbit, and within a decade hope to even weigh the binary’s mass!

David Reneke is an astronomy lecturer and teacher, a feature writer for major Australian newspapers and magazines, and a science correspondent for ABC and commercial radio. Subscribe to David’s free Astro-Space newsletter at www.davidreneke.com