NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Aerothermal Effects of Cavities and Protuberances for High-Speed Sample Return CapsulesExtraterrestrial sample return is a growing component of solar system exploration. Currently, four missions, Stardust, 1 Muses-C, 2 Genesis, and Mars Sample Return, are under development that employ sample return as a prime component of the mission architecture. Respectively, these missions will return samples from the tail of a comet, an asteroid, the solar wind, and, Mars. An important component of these missions and the focus of this paper is the design of the sample return capsule (SRC). The purpose of the SRC is to safely return to Earth any gathered samples for terrestrial analysis. The two major design constraints for any SRC are as follows: 1) it must be able to survive a high-speed Earth entry (11 km/s to as a high as 15 km/s), 2) the mass of the SRC must be as small as possible. Because the SRC mass is carried from Earth to the sample sight and back, the SRC mass is a strong driver in the mission mass budget. Further, for the Mars Sample Return Capsule, planetary protection is another constraint. For this capsule, the probability of planetary contamination at Earth due to an SRC failure at entry must be minimal. For an SRC, a possible failure mechanism is severe local heating as a result of cavities and or protuberances in the SRC forebody heatshield. For example, the Apollo Command Module had a number of cavities and protuberances as part of the baseline designs Wind-tunnel tests of models containing small cavities and protuberances showed severe local heating augmentations in the vicinity of these surface discontinuities.4-5 As another example, the Genesis SRC forebody heat-shield contains penetrations (cavities) to mount the vehicle to the carrier bus. It is expected that these penetrations will also experience a severe local heating environment. A concern is that the large thermal gradients may produce sufficient thermal stress to cause local mechanical failure of the heatshield. Penetrations to the forebody heat-shield can also result from damage at vehicle integration, during launch, or during transportation of the sample return capsule from earth to the sample site and back. For example, the Starting SRC was damaged near the shoulder during the heatshield integration process producing a local surface discontinuity. Also, the Starting SRC traverses through the tail of a comet and is in space for 7 years. Thus, damage to the heatshield as a result of micrometeroid impact is a concern. Finally, it is difficult to characterize the effects of these potential heatshield singularities with ground-test facilities. Either detailed simulation or a dedicated flight test is required.
Document ID
20020061283
Acquisition Source
Ames Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Olynick, David
(NASA Ames Research Center Moffett Field, CA United States)
Kontinos, Dean
(Thermoscience Inst. Moffett Field, CA United States)
Arnold, James O.
Date Acquired
September 7, 2013
Publication Date
January 1, 1998
Subject Category
Astronautics (General)
Meeting Information
Meeting: 37th AIAA Aerospace Sciences Meeting and Exhibit
Location: Reno, NV
Country: United States
Start Date: January 11, 1999
End Date: January 14, 1999
Sponsors: American Inst. of Aeronautics and Astronautics
Funding Number(s)
PROJECT: RTOP 865-10-05
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
No Preview Available