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Astronaut

After the lunar module has “landed”, an astronaut appears from behind the black monolith, as explained in the section on the Lunar Lander. Incidentally, as in the film “2001: A Space Odyssey” the dimensions of the monolith are the squares of the first three numbers, giving ratios of 1:4:9. The astronaut “bunny hops” around the lunar module for the duration of the clock’s performance. This is similar to the three Toucan’s in one of the two versions of the original Guinness clocks. The other version had two Toucans pecking at the Guinness Time tree. Both versions are shown below.

Lunar diorama with monolith hiding astronaut

Two versions of the original Toucans

A video of a “bunny-hopping” astronaut can be seen on the YouTube clip below. An analysis of this video shows that each hop lasts approximately 1.4 seconds in the moon’s 1/6th gravity.

Articulated astronaut

On eBay I found an articulated model of an astronaut that was about 12cm high. This was about the right size to be effective, although way too big for the scale of the Lunar Module, the latter being a little smaller than I had hoped. I had to accept that the two would not be to scale – it was the effect of the astronaut I was after. Similarly, the Toucans are far too big compared with the Guinness Time Tree (unless it was meant to be a bonsai!). As the model had articulated limbs, it enabled me to arrange for the legs to bend while jumping, giving a much more realistic look.

Original Toucans mechanism

The original Toucan mechanism, shown above, is very neat. The mechanism incorporated a turntable operated by a chain and sprocket from a worm-geared motor. The bird figures were supported by rods working freely in vertical guides. The rods had rollers at the lower end, resting on a cam track, so the birds moved up and down, simulating a hopping motion as they moved round. However, this creates two problems. As it is, it does not allow for bending of the knees and hips of the astronaut, so he would simply move up and down. When the his feet touch the surface, they will slide along the surface momentarily which would look rather odd.

I devised an extension to this mechanism that would hopefully overcome both these problems, but I never pursued it as it was a bit “clunky”. I will include part of this design here below just for amusement. I seem to recall the two rings would be shaped like the Toucan cam rings, the inner driving the astronaut’s bottom via a pushrod, the outer driving his feet by a similar pushrod. The main idea is that his feet would be stationary when on the surface due to the operation of the wedge.

Early idea for driving astronaut

After much contemplation I eventually came up with a design that seemed to meet all the requirements although it did have a lot of moving parts. Four identical toothed-wheels are mounted on a frame via axles, one wheel (lower right in mage below) being driven by a 40 rpm geared motor attached to the rear of the frame. This should give about 1 hop every 1.4 seconds under load. All wheels are synchronised together by means of a toothed drive belt running round the outside edges of them (not shown in diagram). The left two wheels are also connected to each other by a coupling rod (similar to those on a steam locomotive) attached to each wheel at 90% of its radius, i.e. almost on the circumference. As the two wheels rotate the coupling rod moves up and down. As the upper wheel is forward of the lower, the motion of the coupling rod will be angled forwards. The top end of this rod will be attached to the astronaut’s bottom via a metal rod - oooh - painful!

A similar coupling rod will connect the right two wheels but will be attached at 50% of the radius. As these two wheels are mounted one above the other, the end of the coupling rod will move vertically up and down. Being mounted at only 50% of the radius, it will not move as much as the other. The end of this second rod will be attached to the astronaut’s feet, again via a rod. The two rods will pass through a circular slot in the base of the lunar diorama. In the diagram here, the red shape shows the locus of the feet and the green shape that of the body. The body rises and falls further than the feet causing the legs to bend at the hips and knees as he rises and falls.

The lower two wheels of the mechanism sit on the bottom board of the main tower underneath the lunar diorama base. The rotation of the wheels causes the mechanism to move forwards. To reduce noise and improve grip, the base is covered with rubberised pond-liner.

Chosen mechanism for driving the astronaut

Astronaut computer simulation video

The video here shows a computer simulation I created of the proposed mechanism. From this you can see the astronaut jumping and stretching. As the mechanism drives along the base board, its path is constrained to a circular path as the back of the frame is attached via a rod to a central pillar directly under the centre of the lunar base. A ball race on the pillar holds the other end of the attaching rod. The picture below shows the pillar without its top board which supports the central disc of the lunar diorama base. The ball race pushes snugly over a thinned down area of the top half of the pillar. Below this are two copper strips formed and soldered into rings that are glued to the pillar. Internal electrical connections are made to these by the brown and blue wires which are powered by the controller.

Astronaut mechanism central column

A jubilee clip is fastened around the ball race, attached to which is an insulating PTFE block. This has two sets of three phosphor-bronze spring contacts to pick up the power from the copper slip-rings. The two white wires send this power to the motor as it drives itself around the central pillar in an anti-clockwise direction when viewed from above. The arm connecting the astronaut mechanism to the ball race has a threaded end which is screwed onto the long M3 screw also attached to the PTFE block. Being threaded it allows some adjustment of length to make sure the rods holding the astronaut are positioned centrally in the circular slot between the inner disc and outer section of the base of the diorama.

Close-up of astronaut carriage mechanism

Astronaut  on his carriage

In the two images of the carriage above you can see a long M3 screw protruding between the two lower wheels. On the end of this screw is a nylock nut which activates a limit switch attached to the rear of the clock frame (just visible in the astronaut image at the top right). This switch signals to the controller when the astronaut is in his home or parked position out of sight behind the monolith. The length of the wire rods attached to the astronaut were designed so that when the astronaut was at his lowest position his feet would be a millimetre or two above the lunar surface so as not to keep hitting it.

Once this was all installed and tested, the lunar surface was installed. This was made from 5mm Foamex split down the middle from front to back which, when finally held together with the self-adhesive lunar base image laminate, would act as a hinge allowing it to be easily folded into a V-shape which could be folded flat into place. Before the laminate was applied, a circular slot about 10mm wide was cut to allow the astronaut’s control rods to project through without touching anywhere in its travel. The pieces of Foamex that constituted the slot were left in place as the printed self-adhesive laminate was carefully applied to the top surface. The slot fillers were then carefully removed to leave the slot covered by the laminate. The adhesive on the rear of this laminate was then carefully removed using methylated spirit and then sliced along the middle of the circular track. The central disc (on which the LEM would descend) was reinforced underneath by gluing extra bits of Foamex across the join, leaving a solid disc. This was then screwed centrally onto the top of the central pillar around which the astronaut revolves. The fishing line guide wires for the LEM were screwed to the top of the disc and tensioned against the springs in the top of the tower. The outer section of the base was then carefully lowered into the bottom of the tower to sit on the frame just above the astronaut trolley mechanism and level with the central disc. The astronaut actuating rods then protruded through the slot, the plastic laminate acting as a flap that concealed the circular slot as shown in the final video.

A black monolith was cut out of Foamex with aspect ratio of 9:4 and positioned in front of where the astronaut stops when he actuates the home position microswitch.

The controller was programmed to operate the astronaut a couple of seconds after the LEM has landed. Once he appears from behind the monolith, the Neil Armstrong speech “That’s one small step for (a) man – one giant leap for mankind” is heard. He continues to hop around the LEM until the closedown sequence parks him behind the monolith, after which the Ascent module “takes off”.

Video showing the astronaut  on his carriage

Apart from tidying up a few things and completing the rear panels, that just about finishes the Main Tower. Now to decide which bit to do next....

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