A Vision of Quantitative Imaging Technology for the Validation of Advanced Flight Technologies

Abstract

Flight-testing is traditionally an expensive but critical element in the development and ultimate validation and certification of technologies destined for future operational capabilities. Measurements obtained in relevant flight environments also provide unique opportunities to observe flow phenomenon that are often beyond the capabilities of ground testing facilities and computational tools to simulate or duplicate. However, the challenges of minimizing vehicle weight and internal complexity as well as instrumentation bandwidth limitations often restrict the ability to make high-density, in-situ measurements with discrete sensors. Remote imaging offers a potential opportunity to noninvasively obtain such flight data in a complementary fashion. The NASA Hypersonic Thermodynamic Infrared Measurements Project has demonstrated such a capability to obtain calibrated thermal imagery on a hypersonic vehicle in flight. Through the application of existing and accessible technologies, the acreage surface temperature of the Shuttle lower surface was measured during reentry. Future hypersonic cruise vehicles, launcher configurations and reentry vehicles will, however, challenge current remote imaging capability. As NASA embarks on the design and deployment of a new Space Launch System architecture for access beyond earth orbit (and the commercial sector focused on low earth orbit), an opportunity exists to implement an imagery system and its supporting infrastructure that provides sufficient flexibility to incorporate changing technology to address the future needs of the flight test community. A long term vision is offered that supports the application of advanced multi-waveband sensing technology to aid in the development of future aerospace systems and critical technologies to enable highly responsive vehicle operations across the aerospace continuum, spanning launch, reusable space access and global reach. Motivations for development of an Agency level imagery-based measurement capability to support cross cutting applications that span the Agency mission directorates as well as meeting potential needs of the commercial sector and national interests of the Intelligence, Surveillance and Reconnaissance community are explored. A recommendation is made for an assessment study to baseline current imaging technology including the identification of future mission requirements. Development of requirements fostered by the applications suggested in this paper would be used to identify technology gaps and direct roadmapping for implementation of an affordable and sustainable next generation sensor/platform system.

Thermographic imaging of the space shuttle during re-entry using a near-infrared sensor

“…Lastly as shown in Figure 9 the image quality has improved greatly from the early mission data collects of STS-121 and STS-115 ( Figure 1). The STS-134 data collect represents unprecedented spatial resolution that defines the future potential for remote quantitative thermography imaging for hypersonic research [25]. This will allow for development of future space vehicle designs.…”

Remote observations of reentering spacecraft including the space shuttle orbiter

“…The NASA Hypersonic Thermodynamic Infrared Measurements (HYTHIRM) team utilized aerial and ground based infrared (IR) imaging systems to infer surface temperature distributions over the viewable windward surface of the Shuttle Orbiter during portions of hypersonic reentry [10][11][12][13][14][15][16][17][18][19][20][21][22][23]. The in-flight thermal imaging capability, discussed herein, represented several years of advocacy within the aerothermodynamics technical community [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] The genesis of the HYTHIRM project and the use of optical systems to provide surface temperature was motivated by the Shuttle Columbia Accident Investigation (CAI) [39][40] and the subsequent Return-to-Flight (RTF) effort [41].…”

Assessment of CFD Hypersonic Turbulent Heating Rates for Space Shuttle Orbiter

“…Coverage of the boundary layer transition experiment includes the flight data, 2 associated wind tunnel tests, 4 and the present comparisons with numerical simulations. HYTHIRM topics include a project perspective, 5 the conversion of radiant intensities into temperature measurements, 6 and mission operations. The present report assesses computational fluid dynamics codes for the simulation of hypersonic turbulent flows, using convective heating rates as the metric.…”