Infrared Sensing Aeroheating Flight Experiment: STS-96 Flight Results

Abstract

Major elements of an experiment called the Infrared Sensing Aeroheating Flight Experiment are discussed. The primary experiment goal is to provide reentry global temperature images from infrared measurements to define the characteristics of hypersonic boundary-layer transition during flight. Specifically, the experiment is to identify, monitor, and quantify hypersonic boundary layer windward surface transition of the X-33 vehicle during flight. In addition, the flight data will serve as a calibration and validation of current boundary layer transition prediction techniques, provide benchmark laminar, transitional, and fully turbulent global aeroheating data in order to validate existing wind tunnel and computational results, and to advance aeroheating technology. Shuttle Orbiter data from STS-96 used to validate the data acquisition and data reduction to global temperatures, in order to mitigate the experiment risks prior to the maiden flight of the X-33, is discussed. STS-96 reentry midwave (3-5 µm) infrared data were collected at the Ballistic Missile Defense Organization/Innovative Sciences and Technology Experimentation Facility site at NASA-Kennedy Space Center and subsequently mapped into global temperature contours using ground calibrations only. A series of image mapping techniques have been developed in order to compare each frame of infrared data with thermocouple data collected during the flight. Comparisons of the ground calibrated global temperature images with the corresponding thermocouple data are discussed. The differences are shown to be generally less than about 5%, which is comparable to the expected accuracy of both types of aeroheating measurements.

The Hythirm Project: Flight Thermography of the Space Shuttle During Hypersonic Re-Entry

“…Advancements in capability led to additional insight gained during the imaging attempts with a land-based system in 1999 6,7 . This methodical approach was continued with incremental experience gained during attempts associated with the 2005-6 ad-hoc missions flown in support of RTF 13,15 .…”

“…Quantitatively, if surface temperatures associated with a hypersonic laminar and/or fully turbulent boundary layer flow can be inferred from calibrated in flight imagery, they could be used to verify engineering models or numerical predictive methods and associated turbulence models. While most aerospace applications of infrared thermography have been limited to wind tunnel testing, this measurement technique has been utilized during several Shuttle entries over the past 25 years to obtain flight data [6][7][8][9][10][11][12][13][14][15] . The renewed interest in thermal imagery during Shuttle entry was initially motivated by the desire to reduce uncertainties associated with an empirical strategy to predict BLT onset.…”

Remote observations of reentering spacecraft including the space shuttle orbiter

“…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]. Per the recommendation of the CAI board, a suite of engineering tools was developed to determine the implications of a damaged TPS.…”

Remote Infrared Imaging of the Space Shuttle During Hypersonic Flight: HYTHIRM Mission Operations and Coordination

“…A limited series of infrared imaging experiments have been conducted in the past [1][2][3][4][5][6][7] , dating back to the third Space Shuttle flight in the early 1980's that have attempted to acquire infrared imagery of the Orbiter during descent. More recently, airborne assets intended to image the Orbiter on ascent were utilized in an "adhoc" fashion to obtain infrared imagery during reentry.…”