Giant Magellen Telescope High-Resolution Near-Infrared Spectrograph (GMTNIRS)


 
 
 
 
 
 
 

Photo credits: GMTNIRS telescope rendering – GMT; all other images – Center for Electromechanics, University of Texas @ Austin

The Giant Magellan Telescope (GMT) is scheduled for commissioning in 2024 and is one of the next generation of extremely large ground-based telescopes.  The University of Texas Astronomy Department, in partnership with The Korea Astronomy and Space Science Institute (KASI) and Kyung Hee University, were selected to perform a conceptual design of one of six possible first-light instruments to be installed on the GMT: the High-Resolution Near-Infrared Spectrograph (NIRS).   In part because of CEM’s contributions, GMTNIRS was ultimately selected as a first-generation instrument for GMT.

Design / Solid Modeling:

  1. Served as CEM’s program lead coordinating with UT-Astronomy, KASI engineers in South Korea and an optical consultant in New Zealand.
  2. Responsible for the optical bench layout and design, a highly iterative process as the optical system developed.
  3. Designed multiple radiation shields to address both thermal and optical (e.g. stray light) concerns.
  4. Designed and evaluated optical bench mounting options within the cryostat to accomplish both thermal and structural requirements.

 Analysis:

Performed all steady state and transient thermal analyses, which also guided placement of the cryocoolers. Requirements included:

  1. Entire cryostat operates in 10-7 torr vacuum.
  2. Ambient temperature range: -10˚C to 27˚C (263-300 K).
  3. Maintain fixed temperatures for optical modules of 37 and 65 K and optical bench temp of 70 K.
  4. Ensure all temperature gradients were less than 4 K/100 mm.
  5. Optic components cooling/warming rate < 1 K/min.
  6. Full cooldown and warmup cycles are achievable in less than 7 days.

Publication:

T.A. Beets, J.H. Beno, M.S. Worthington, “GMTNIRS mechanical design,” Proc. SPIE Astronomical Telescopes and Instrumentation, Amsterdam, Netherlands, July 1-6, 2012, paper no. 8446-301.