We're done with M2 now & before we get started on the CGH tests to check the figure of M3 & the overall alignment of the system, it's time to wash M3...
First the mirror - still in the cell that bolts on to the rest of the SAC cage - had to be lifted out of its storage box.
It could then be lowered onto the washing trolley & wheeled into the wash bay next to the clean room.
Safely in the washing area, the mirror cover was removed... Not quite as bad as M5 was, but still pretty disgusting!
It's even more gruesome up close - Eeeuw :(
Since the SAC's usually at an angle of 37 degrees, the down-hill side's particularly bad as years worth of dust & muck's collected in that sector.
The mirror cell had to be water-proofed before the washing could start - black plastic bags & loads of duct tape did the trick!
Tight-fitting plastic skirts were then stretched over the mirror to help channel the water away.
De-ionised water was used to rinse all the loose dust & dirt down the central hole...
Within a few minutes the mirror was already looking great!
Confident that all abrasive material had been flushed off the mirror, it was repeatedly sprayed with a 10 grams/litre solution of sodium lauryl sulphate.
The mirror was soaked like this for several minutes...
With Jonathan continually spraying the mirror, Hitesh could start the delicate process of drag-wiping the surface with wads of cotton wool soaked in sodium lauryl sulphate.
The mirror was then thoroughly rinsed with distilled water.
The clean surface sheds water beautifully!
Everyone watched eagerly while Jonathan blasted away the remaining drops of water.
Time then for a careful inspection of the surface... It looks Fantastic, but we're not entirely happy with a couple of areas so we'll repeat the washing process tomorrow...