Nasa hopes to build stairway to heaven*

US scientists compete to find technology that could replace costly rockets

Robin McKie, science editor
Sunday September 3, 2006
The Observer

In a few weeks, scientists from across the world will gather in the New
Mexico desert to compete for one of the strangest - and most ambitious -
technological competitions ever devised.

Some researchers will unveil robots, powered by solar panels, that will
climb long lengths of cable. Others will demonstrate materials so light
and strong that mile-long stretches of the stuff could be hung in the
air without snapping. And some will highlight their plans to launch
satellites carrying sets of mini-probes tethered together, to discover
how they behave in space.

All these different projects are united by one extraordinary goal: to
build a stairway to heaven. Each of the groups that will gather in New
Mexico is competing to win a Nasa prize set up to encourage
entrepreneurs to start development work on the technology needed to
create a space elevator. Such a device would involve constructing a
23,000-mile cable that could pull men and goods into orbit without
blasting them there on top of expensive, and dangerous, rockets.

'I think there are going to be lots of people that rise to this
challenge,' said Michael Laine, president of the Washington-based
company LiftPort, which will take part in the competition. 'We're at the
beginning of something really great.'

The key feature of a space elevator would be the use of a satellite that
will orbit almost 23,000 miles above Earth. At this altitude, known as
geostationary orbit, the orbital period of a satellite moving around the
globe matches Earth's rotation. The craft then hovers over a single spot
on the equator.

However, a space elevator would have one extra key feature: a massive
cable would be lowered from it to link it to the ground where it would
remain fixed, like a tube line to the stars.

It sounds like science fiction. And indeed for the past 30 years that is
how most people have viewed the concept of a space elevator, after the
idea - originally put forward by the Russian scientist Yuri Artsutanov
in 1960 - was made famous by Arthur C Clarke in his 1978 novel, The
Fountains of Paradise. At the time the book's ideas were praised for
their soundness, though scientists noted that the incredibly strong
materials needed to build a space elevator were well beyond the
technology of the day.

But science has made enormous advances since 1978, particularly in the
development of incredibly light but strong substances that could be used
to construct the space elevator cable. In particular, the development of
carbon nanotubes - made of highly robust webs of carbon atoms - have
raised the promise that a space elevator may one day become reality.

And for Nasa that cannot come a moment too soon. Despite decades of
putting rockets into space, the agency has never managed to make any
real reductions in launch costs in that time. Hence its decision to back
a competition to stimulate space elevator technology. 'With a space
elevator, Nasa could build probes that they weren't able to do before;
they could do new research on different applications of the space
elevator,' said Bradley Edwards, an entrepreneur who played a key role
in helping to set up the space elevator competition.

Several US companies and groups of university researchers, plus
Canadian, German and Spanish scientists, have promised to bring their
devices and put them through their paces at next month's space elevator
competition. Prizes will be worth more than $400,000 in total, including
one for a robot that will have to climb a 60-metre cable powered only by
photovoltaic cells, and another for the creation of tether lighter and
stronger than those made of materials now available commercially.

It promises to be a close-run thing. As New Scientist magazine reported
last week, the best performing robot last year managed an ascent of only
12 metres up a cable before it stalled, while no material came close to
meeting the standards needed for building a space elevator. In short, we
may have to wait a little bit longer than anticipated to build that
stairway to heaven.