Herschel telescope flight model at ESTEC

The Herschel telescope's primary mirror is the largest mirror ever built for space. It is made out of 12 silicon carbide (SiC) petals brazed together and coated with a thin aluminium reflective layer. The SiC provides a rigid but lightweight structure with the telescope mass totalling at about 320 kg.

In the morning on Friday 18 January, the flight model of the 3.5-metre diameter telescope arrived at ESTEC in Noordwijk on its transporter truck. Upon arrival the outside of the telescope container was first cleaned before the transport was turned to cleanroom loading bay-airlock #3 for unloading of the container holding the large telescope.
On 24 January, the unpacking of the telescope was performed in the cleanroom, starting with the lifting of the transport container cover. The images below show the telescope - still with a white protective cover - being hoisted from its transport stand onto its ground handling system.

In the following days a thorough inspection of the telescope's condition after transport was performed - the telescope incoming inspection. The mirrors were inspected after removal of the telescope's protective cover.

The next major milestones for the telescope will be a fit-check of the telescope's interface with the spacecraft on a reference plate (simulating the actual spacecraft interface) and the M1/M2 distance measurement of the telescope's primary and secondary mirror. Eventually the telescope will be integrated on top of the Herschel cryostat vacuum vessel that is currently set up for its cooldown and filling of the cooling system with liquid helium.

Source: ESA Science & Technology
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