Multi-Object Optical and Near-infrared Spectrograph (MOONS)

The Multi Object Optical and Near-infrared Spectrograph for the VLT (MOONS) is a multi-scope instrument that is also aiming to probe galactic archaelogy, galaxy evolution and cosmology. It will obtain near infrared spectra for millions of stars and galaxies.

MOONS will be installed on the VLT 8-meter telescope at Paranal Observatory in 2021. MOONS is a European project led by the Royal Observatory of Edinburgh.

The MOONS fiber system will consistutes of 1000 fiber-positioning actuators following an hexagonal distribution on the focal plane with a ~3cm distance between actuators (center to center).

 The MOONS robot is a robotic positioner designed by the UK Astronomy Technology Centre for the MOONS project. The mechanical concept consist of two coupled rotations. The beta arm has about twice the length of the alpha arm. The robot cannot reach its own center, but the beta arm is long enough to reach the center of its 6 neighbours which gives a better overall coverage of the focal plane. The position accuracy of this robot is 20 micrometers RMS.

In this design the motor of the second stage is moving with the rotation of the first stage. The advantage of this solution is that there is no gear transmission (other than reduction gears) between the motors and the arms.