Design and Characterization of a Balloon-Borne Diffraction-Limited Submillimeter Telescope Platform for BLAST-TNG

TL;DR

This paper details the design, modeling, and preflight testing of a large, diffraction-limited submillimeter telescope platform for balloon-borne observations, enabling high-resolution mapping of interstellar dust and magnetic fields.

Contribution

It introduces a novel 2.5-meter balloon-borne telescope with advanced optical and thermal modeling, achieving diffraction-limited resolution for submillimeter astronomy.

Findings

Successful optical metrology and finite element modeling predict diffraction-limited performance.

Thermal and mechanical stress analyses ensure stability and minimal pointing errors.

Preflight characterization confirms readiness for scientific observations.

Abstract

The Next Generation Balloon-borne Large Aperture Submillimeter Telescope (BLAST-TNG) is a submillimeter mapping experiment planned for a 28 day long-duration balloon (LDB) flight from McMurdo Station, Antarctica during the 2018-2019 season. BLAST-TNG will detect submillimeter polarized interstellar dust emission, tracing magnetic fields in galactic molecular clouds. BLAST-TNG will be the first polarimeter with the sensitivity and resolution to probe the $\sim$0.1 parsec-scale features that are critical to understanding the origin of structures in the interstellar medium. With three detector arrays operating at 250, 350, and 500 $\mu$m (1200, 857, and 600 GHz), BLAST-TNG will obtain diffraction-limited resolution at each waveband of 30, 41, and 59 arcseconds respectively. To achieve the submillimeter resolution necessary for its science goals, the BLAST-TNG telescope features a 2.5 m aperture carbon fiber composite primary mirror, one of the largest mirrors flown on a balloon platform. Successful performance of such a large telescope on a balloon-borne platform requires stiff, lightweight optical components and mounting structures. Through a combination of optical metrology and finite element modeling of thermal and mechanical stresses on both the telescope optics and mounting structures, we expect diffraction-limited resolution at all our wavebands. We expect pointing errors due to deformation of the telescope mount to be negligible. We have developed a detailed thermal model of the sun shielding, gondola, and optical components to optimize our observing strategy and increase the stability of the telescope over the flight. We present preflight characterization of the telescope and its platform.