Sunday, March 27, 2011

The payload goes back up!

Further trial-fitting of the ADC showed that the installation, to be done in a couple of weeks time with everything else in place up there, would be way too difficult with such limited access & minimal clearance.  Yet more nerve-wracking NRS surgery was needed so we had Jonathan on the vacuum cleaner & Eben driving the router - just a few centimetres above the SAC!

An elaborate scheme to keep all the carbon fibre shavings from landing up on M5 & M3 involved a sheet of bubble wrap, a piece of corex, adhesive covering material from Eben's model airplanes (sticky side up), plenty of duct tape, a vacuum cleaner & some good karma.  We were all Very glad when this process was over!

Next on our Sunday afternoon line-up was the lifting of the payload...  With all the hatches bolted on, the rotating structure was wheeled out into the loading bay.

The whole lot was rigged up & tilted to the required 37 degrees before being lifted with the dome crane.

Up through the hatch leading to the telescope floor.

& then onward & upward to the tracker...

Charl, Eben, Jono & Chris were up there to meet it.

& guided it down into position inside the NRS.

Once the payload was bolted into position & the team felt sure that everything was clear, they rotated rho to make sure nothing crashed or pinched.

No problems - well done guys!  Nice of Eben & Charl to coordinate their outfits for the big occasion, don't you think?

Prior to the lift, the SAC reference mirror was bolted onto the back of M4 & then after dinner we went up the CCAS tower to check the alignment of the payload with respect to the SAC. 

With the tracker at its static offsets, the alignment telescope in the tower was trained on the SAC reference mirror's cross-hair & then squared up in tip & tilt to get the alignment telescope on the optical axis.

A target for the alignment telescope was mounted in a fixture that centrally locates in the floor of the payload & then the bar with the cross-hair (used in the SALTICAM alignment) was bolted in place on the top of the rotating structure - the 2 then define the axis of the payload.

Although not a hugely sensitive test, since the separation between these 2 points is small compared to their distance from the alignment telescope, the target & cross-hair were well aligned.  This shows that the payload tip/tilt is ok & since this point was close enough to the optical axis (given the known problem of the rho stage wobble), no adjustments were made to the rotating structure.

It was, in fact, time to put an end to this extremely busy weekend!  Down the hill, to the porch behind the hostel where, under an absolutely perfect Karoo sky & midst a mini-plague of locusts, we toasted SALTICAM's return to the tracker :)

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