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Ellen's Spacesuit Diary Day 1 2 3

Day One

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 quite long.
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 can pull.

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 board.

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!

 



Ellen suited for space
Scientist's Diaries

How did the rest of the Rough Scientists approach the spacesuit task? Find out in their diaries:

Iain
Jonathan
Kathy
Mike