Challenge: To build a pump that will circulate water
through tubing. The tubing will initially hold warm
to hot water (ambient Death Valley temperature in summer
is typically over 45 degrees Celsius). The pump will
push the water through the tubing, which enters a series
of coils inside a fridge that Kathy, Mike, and Ian are
making. The water in the tubing is then cooled and finally
circulated out of the fridge and through our Rough Science
"spacesuit" in order to cool the "astronaut".
The key issues:
The pump has to push or pull the water with sufficient
force that it moves through the tubing, which may be
The water in the tubing has to be in the fridge long
enough to cool off. With the ambient air temperature
potentially being very high in Death Valley, the water
may need to spend lots of time in the fridge, so we’ll
have to coil lots of tubing in the fridge to give it
time to cool down.
The water in the tubing has to stay cool long enough
to reach the person in the spacesuit and cool the person
down before the water (now warm) returns to the fridge.
The tubing connecting the fridge and the person should
be as short as possible and should be insulated from
the ambient air temperature, so it doesn’t warm
up too much between the fridge and the person.
Other things to accomplish:
Make and connect the spacesuit and tubing system.
Build a wagon for the fridge system that the astronaut
In terms of the tubing, we know that copper is a great
conductor, not an insulator. Thus, we want copper tubing
in the fridge system so the hot water entering it cools
quickly. We also want copper tubing in the space suit,
so the cool water cools the astronaut.
We want tubing that is a good insulator, however, going
from the fridge to the astronaut and from the astronaut
to the fridge so the water isn't heated up unnecessarily
by the Death Valley air. We’ll use plastic tubing
for these connections. Though we are pretty confident
that the plastic is a better insulator than the copper,
we don’t know how good an insulator it is (and
really don’t have time to figure this out), so
we will place the plastic tubing in a larger plastic
tube which is covered with aluminium foil. This will
be helpful, first, because the outer tube is much larger
than the tube carrying the water. This will allow for
an insulating air space. Second, the aluminium foil
will reflect sunlight, so the tubing will absorb less
heat through solar radiation.
Jonathan is absolutely brilliant, and he has so much
experience building things. Based on an idea of his,
we had a pump knocked together by mid afternoon. Basically,
we used a power screwdriver as the motor. We connected
a hex wrench as the bit and put it through a little
system we made of wood, copper tubing, and screws that
looks like a miniature Ferris wheel. The key parts are
the lengths of copper tubing that push the water through
the plastic tubing by pushing the plastic tubing, which
is stationary, down against a board.
It is hard to explain in words, but obvious when observed.
If you haven’t seen the show, try this. Take a
piece of tubing or a straw. Put water in it and then
squeeze one section while pushing forward. The water
moves forward. Basically, the device Jonathan designed
and I helped build does the same thing over and over;
each time a piece of copper tube reaches the bottom
of the wheel, it pushes water forward in the tube by
squeezing the tube between the copper section and the
Cool. We filled a plastic tube with water, which we
dyed red with common food colouring in order to see
it better, and turned the screwdriver on. We watched
small air bubbles go round and round, which indicated
the water must be travelling, too!
Seems like success on day one. Hmm, that’s a
bit unusual. I’m not one to be a sceptic, but
this may be too good to be true!