Dean Kontinos

Post-Flight Evaluation of Stardust Sample Return Capsule Forebody Heatshield Material

Phenolic Impregnated Carbon Ablator (PICA) was developed at NASA Ames Research Center under the lightweight ceramic ablator development program in the ’80s. PICA’s low density (~ 0.27g/cc), coupled with efficient ablative capability at high heat fluxes, makes it an enabling technology for the Stardust mission. This paper discusses the evaluation of three cores extracted post flight from key locations on the forebody heatshield of the Stardust Sample Return Capsule (SRC). Core locations included a near stagnation core, a flank core, and a segment taken from the shoulder of the heatshield. Evaluation included density profiles, recession determination, a thermal analysis profile, PICA bondline examination, strength assessment of remaining virgin PICA, an emissivity profile, a chemical analysis profile, and a microstructural analysis. Results show good agreement in comparisons of experimental density profiles and profiles derived from FIAT and in recession comparisons from measured values and FIAT predictions for the flank core. In general, the PICA material examined in the cores is in good condition and intact. Impact damage is not evident, and the only degradation observed was that caused by heating on entry. A substantial amount of virgin PICA was present in all cores examined.

Post-Flight Analysis of the Stardust Sample Return Capsule Earth Entry

This paper presents an overview of post-flight activities for assessing the entry performance of the Stardust Sample Return Capsule and the analysis tools used to design it. Three sources of information are leveraged: the recovered return capsule thermal protection system, airborne observations of the entry using instruments that provide spectral resolution of the hot return capsule and shock layer gasses, and radar signature during the terminal descent stage. The paper describes the objectives of the post-flight analysis, the information sources, and the methods of analysis. Sample results from detailed analyses are presented.

Surface Heating from Remote Sensing of the Hypervelocity Entry of the NASA GENESIS Sample Return Capsule

An instrumented aircraft and ground-based observing campaign was mounted to measure the radiation from the hypervelocity (11.0 km/s) reentry of the Genesis Sample Return Capsule prior to landing on the Utah Test and Training Range on September 08, 2004. The goal was to validate predictions of surface heating, the physical conditions in the shock layer, and the amount and nature of gaseous and solid ablation products as a function of altitude. This was the first hypervelocity reentry of a NASA spacecraft since the Apollo era. Estimates of anticipated emissions were made. Erroneous pointing instructions prevented us from acquiring spectroscopic data, but staring instruments measured broadband photometric and acoustic information. A surface-averaged brightness temperature was derived as a function of altitude. From this, we conclude that the observed optical emissions were consistent with most of the emitted light originating from a gray body continuum, but with a surface averaged temperature of 570 K less than our estimate from the predicted heat flux. Also, the surface remained warm longer than expected. We surmise that this is on account of conduction into the heat shield material, ablative cooling, and finite-rate wall catalycity. Preparations are underway to observe a second hypervelocity reentry (12.8 km/s) when the Stardust Sample Return Capsule returns to land at U.T.T.R. on January 15, 2006.