Venting and High Vacuum Performance of Low Density Multilayer Insulation

Abstract

The NASA Exploration Program is currently studying the use liquid oxygen, liquid methane and liquid hydrogen for propulsion in future spacecraft for Exploration of the Moon and Mars. This will require the efficient long term, on-orbit storage of these cryogenic propellants. Multilayer Insulation (MLI) will be critical to achieving the required thermal performance since it has much lower heat transfer than any other insulation when used in a vacuum. MLI with a low density (≤ 10 layers/cm) has been shown in previous work to be the most mass efficient. The size and mass constraints of these propulsion systems will not allow a structural shell to be used to provide vacuum for the MLI during ground hold and launch. The baseline approach is to purge the MLI during ground hold with an inert gas which is then vented during launch ascent and on-orbit.This paper presents the results on experimental tests and modeling performed by Ball Aerospace on low density, non-perforated MLI used to insulate a cryogenic tank simulating an Exploration cryogenic propellant storage vessel. These include measurements of the rate of venting and of the heat transfer of gas filled insulation, fully evacuated insulation and during the transition in between. Results of transient computer modeling of the MLI venting and heat transfer process are also presented. Previous work by some of the authors performed vent testing using MLI with perforations and slits and a slow pump down rate.

Green Propellant Infusion Mission Program Development and Technology Maturation

“…IMLI is an advanced multilayer insulation system developed by Quest Product Development (now spun off into Quest Thermal Group) and Ball Aerospace in partial cooperation with NASA through the Small Business Innovative Research (SBIR) program with Phase I, II, and III funding ( Figure 16) 36,37 . Instead of using a netting spacer between the reflectors of the IMLI, discrete posts are used to support the blankets and keep them from touching one another.…”

Green Propellant Infusion Mission Program Overview

“…The GPIM propulsion subsystem is incorporating advanced thermal insulation material developed by Ball Aerospace and Quest Technologies under STMD funding from the Game Changing Development program 12 . This Integrated Multi-Layer Insulation (IMLI) (Figure 8) has been under development for several years and is the basis for a variety of advanced insulation technologies.…”

Stress Characteristics and Structural Optimization of Spacecraft Multilayer Insulation Components

“…The components are composed of nylon nets and stacks of thin insulation films. The material properties, film density, and other structural parameters of the components can affect the thermal performance of the components, and improving the thermal insulation properties of the components is an important research focus in this field [8][9][10][11]. Therefore, the structural design of components operating in complex conditions is particularly important.…”

“…Aerospace 2023, 10, x FOR PEER REVIEW 2 of 20 the components is an important research focus in this field [8][9][10][11]. Therefore, the structural design of components operating in complex conditions is particularly important.…”