— a compressive structure supported
from the bottom up.
No known material, however, has
the compressive strength to support a
free-standing tower tall enough to
reach geostationary orbit. Other
scientists, however, picked up where
Tsiolkovsky left off.
The modern proposal for a space
elevator is to deploy a cable or tether
(or ribbon, if you will), from a satellite
down to Earth. A counterweight on
the tether in space means that the
structure is under tensile stress instead
of compressive stress. Even though
we’re talking about serious tensile
stress, the tensile structure deals with
forces much more manageable than a
compressive structure about as tall as
110,000 Eiffel Towers.
Nowadays, we have a material
that makes such a structure
feasible: carbon nanotubes.
With an achievable structure
within reach, the space elevator
has been the subject of a
renewed research effort, and
detailed proposals have
emerged that fill in some of the
important specifics about the
project such as location, space
debris avoidance, and other
One proposed space
elevator would climb at what
sounds like a speedy 200 km/h.
That means that the trip to
geostationary orbit would only
take a mere seven and a half
days. That’s a long
time to listen to
The Girl From
One way in
which the space elevator has been
pushed closer from the realm of
science fiction into the realm of
science fact is through competition.
Much like the Ansari X-Prize, several
organizations seek to spur innovation
with a monetary incentive. One such
organization was Elevator:2010, a
partnership between the Spaceward
Foundation and NASA Centennial
competitions for five years beginning
back in 2005, and presented two
different challenges. One was to build
the strongest tether possible. The
other was to create a wirelessly
powered climber capable of ascending
a tether at a certain speed.
RoboGames also included a
ribbon climbing challenge inspired by
the space elevator. For their challenge,
teams had to build a robot to ascend
a tape ribbon up to six meters high,
pause in the middle on command,
and stop automatically at the top.
Bonus points were awarded to teams
who beamed power from the ground
to their robot.
A challenge like ribbon
climbing may be daunting to the
uninitiated, but as with any
challenge the key is to break it
down into manageable steps. A
key part of the ribbon climber
that we were keen to tackle
given our background was the
climbing mechanism itself.
Unlike some of the other
challenges inherent in a ribbon
climber, the climbing mechanism
appears to be rather
Our initial design inclination
was to make something akin to
a softball shooter. We drew
some inspiration from Deltamo,
SERVO 12.2013 69
SKETCHING OUT A DESIGN.
A BULKY BASE.
THE FIRST DRAFT OF OUR RIBBON CLIMBER.