Ewing M.E.,ATK Aerospace Systems |
Pincock B.,ATK Aerospace Systems
Heat Transfer Engineering | Year: 2017
An isoconversional modeling approach has been considered in the modeling of heat transfer and pyrolysis in a charring material. The isoconversional approach is appealing due to the use of only a single reacting component as opposed to the multi-component model typically used. This reduces the number of required field variables which reduces numerical demands in large multi-dimensional models. In this study, isoconversional parameters have been reduced from available test data for a generic ablative material. The results were evaluated by implementing the approach into a 1-D ablation heat transfer program and modeling the thermal and decomposition response of a charring material subjected to an elevated surface temperature. The results were compared to the same modeling using a traditional multi-component Arrhenius approach. Modeling outputs showed that the two methods produced very similar results when proper care was taken in the tabulated parameters of the isoconversional model which is susceptible to variations in supporting test data and is sensitive to table resolution. The results of this study indicate that the isoconversional model provides a viable alternative to the widely used multi-component approach. © 2017 Taylor & Francis Group, LLC.
Ewing M.E.,ATK Aerospace Systems |
Laker T.S.,ATK Aerospace Systems |
Walker D.T.,Infinite Technologies, Inc
Journal of Thermophysics and Heat Transfer | Year: 2013
A unique numerical method has been developed for solving one-dimensional ablation heat transfer problems. This paper provides a comprehensive description of the method, along with detailed derivations of the governing equations. This methodology supports solutions for traditional ablation modeling including such effects as heat transfer, material decomposition, pyrolysis gas permeation and heat exchange, and thermochemical surface erosion. The numerical scheme uses a control-volume approach with a variable grid to account for surface movement. This method directly supports implementation of nontraditional models such as material swelling and mechanical erosion, extending capabilities for modeling complex ablation phenomena. Verifications of the numerical implementation are provided using analytical solutions, code comparisons, and the method of manufactured solutions. These verifications are used to demonstrate solution accuracy and proper error convergence rates. A simple example of a mechanical erosion (spallation) model is also provided to illustrate the unique capabilities of the method© 2013 by the American Institute of Aeronautics and Astronautics, Inc.
Killpack M.O.,ATK Aerospace Systems |
Lesley M.W.,ATK Aerospace Systems |
McClennen W.H.,ATK Aerospace Systems |
Li P.,ATK Aerospace Systems
Journal of Adhesion | Year: 2013
Delaminations in aluminum-to-phenolic resin-cured ethylenepropylene-diene monomer (EPDM) rubber bondlines were studied by a variety of techniques, including surface chemical analysis, microscopy, gas chromatography=mass spectrometry (GC=MS), pyrolysis gas chromatography=mass spectrometry (PyGC=MS), and analysis of solvent extracts from the failures by high performance liquid chromatography=mass spectrometry (HPLC=MS). The rubber was bonded to the aluminum using a common, commercially available metal primer and rubber-to-metal adhesive. The locus of failure was cohesive in a thin layer of rubber near the rubber= adhesive interface. Two chemical contributing factors to the debonding were found. One was the use of a cleaning solvent (d-limonene) that reacts with rubber and competes with normal cross-linking. Another was an incompatibility with the rubber-tometal adhesive that causes disproportionation and breakdown of the phenolic resin. Both mechanisms are expected to cause a lowered cross-link density and reduce rubber tensile strength, leading to weakened rubber near the rubber=adhesive interface. Copyright © Taylor & Francis Group, LLC.
Elliott D.A.,Jet Propulsion Laboratory |
Weiler M.,ATK Aerospace Systems |
Manning E.M.,Jet Propulsion Laboratory |
Pagano T.S.,Jet Propulsion Laboratory |
And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013
The Atmospheric Infrared Sounder (AIRS) is a grating array infrared hyperspectral sounder with 2378 channels from 3.75 to 15.4 microns with spectral resolution 1200 to 1400 depending on the channel. AIRS was designed as an aid to weather prediction and for atmospheric process studies. It produces profiles of atmospheric temperature and water vapor. Because of its spectral coverage and spectral resolution it is sensitive to a number of trace atmospheric constituents including CO2, CO, SO2, O3, and CH4. The AIRS sensitivity, stability, and long life have led to its use in climate process studies and climate model validation, both of which place far more stringent requirements on calibration than weather forecasting does. This paper describes results from several special calibration sequences, originally developed for prelaunch testing, that have been used to monitor the AIRS calibration accuracy and instrument health on-orbit, including the scan mirror, space view response, and channel health. It also describes reanalyses of pre-launch calibration data used to determine calibration parameters. Finally, it shows comparisons of AIRS radiometry with two other hyperspectral infrared sounders presently in space-IASI and CrIS. © 2013 SPIE.
McEachen M.E.,ATK Aerospace Systems
54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference | Year: 2013
A new variant of the venerable Coilable boom has been designed, built, and tested to validate the challenging structural requirements of the GEMS X-Ray Polarimeter deployable focal length spacecraft observatory. Until its cancellation by NASA in mid-2012, the Gravity and Extreme Magnetism SMEX (GEMS) X-ray polarimeter mission, led by the Goddard Space Flight Center (GSFC) was built around this new boom design which, thanks to its compact stowage and low mass, enabled the use of a relatively affordable, small launch vehicle. The work performed to date has established a completed Flight design, refined and validated by ground testing of a flight-like Engineering Test Unit (ETU), which demonstrated extremely tight deployed placement repeatability. Over dozens of ground deployments, this ETU deployed its 45-kg optical payload simulator to the same position at 3.8 m of linear extension within a 0.025 mm standard deviation, in all translational degrees of freedom (DOFs). In addition to the hardware ground testing, detailed thermal-structural analysis was performed which predicted orbital thermal distortions (including eclipse) on the order of 0.1 mm in all translational DOFs, and 5 arcsec in all rotational DOFs. © 2013 by Michael E. McEachen.
Cepeda-Rizo J.,Jet Propulsion Laboratory |
Rodriguez J.-I.,Jet Propulsion Laboratory |
Bugby D.-C.,ATK Aerospace Systems
AIP Conference Proceedings | Year: 2012
A methane cryogenic heat pipe with a liquid trap for on-off actuation was developed by ATK for use on Jet Propulsion Laboratory's Space Interferometer Mission Lite (SIM Lite) pre-Phase A hardware technology demonstration tests. The cryogenic heat pipe coupled to a cold radiator at 160K provides cooling to the Charged Coupled Device camera focal planes. The heat pipe was designed for a transport capacity of 15 W across a 1.5 m span through a near room-temperature spacecraft environment. A key and driving requirement for the heat pipe was the need for switching the heat pipe on and off needed to support low power decontamination cycles to near room temperature of the cryogenic focal planes. The cryogenic heat pipe is turned off by removing the methane working fluid from the heat pipe and storing in the liquid trap. The heat pipe is turned-on by simply re-introducing the working fluid from the liquid trap. This on-off switching capability is a key requirement for cryogenic heat pipes used with passive or active cryocoolers for cooling focal planes or optics. This switching capability provides a means to decouple a cold focal plane or optics from a redundant stand-by cryocooler or a passive cooler when in need for a decontamination cycle. © 2012 American Institute of Physics.
Steele M.,ATK Aerospace Systems
AIAA SPACE 2013 Conference and Exposition | Year: 2013
The Athena RideShare™ launch service, announced by Lockheed Martin and ATK in 2011, is a game-changing approach that lowers launch costs and provides scheduled access to space for small satellites and cubesats. The Athena RideShare launch service is an extension of a familiar concept, the Post Office's Priority Mail Flat Rate Boxes. If payload fits into the designated volume envelope and mass limit, the customer pays one low flat rate to get to space. Despite the simplicity of the model, there are significant challenges to execute this idea. Both technical and programmatic challenges have surfaced in the pursuit of setting up this service. Technical challenges include: • Integrating a variety of mass and volumes in a dynamic launch environment • Adapting the launch profile to accommodate a wide range of orbital altitudes • Verification that all payloads will not adversely impact the mission or other payloads Programmatic challenges have turned out to be the bigger issue, however. Issues include: • Confirming payloads for the manifest • Scheduling to ensure all payloads are delivered on time • Developing appropriate contracts for ride share missions With a RideShare model, low cost, reliable access to space is indeed possible; however, it is not as easy as it looks. Both technical and programmatic challenges identified can be overcome, and it is easy to see that ride share will become the standard approach for purring small payloads into space in the near-term future.
Sanders J.T.,ATK Aerospace Systems
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010
Ultraviolet light attenuation was measured by the Martin Marietta Corporation in 1980 between the wavelengths of approximately 115 nanometers to 300 nanometers. These data are compared to the light attenuation calculated using x-ray interactions with matter, pioneered by the Lawrence Berkley National Laboratories. The Center for X-Ray Optics provides a methodology to calculate light attenuation from x-ray light to 124-nm ultraviolet light. There is a slight overlap in the data, allowing for a comparison of commonly outgassed species from the base materials reported in the Martin Marietta document. © 2010 SPIE.
McEachen M.E.,ATK Aerospace Systems
Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference | Year: 2011
A deployable Telescope Optical Boom (TOB), derived from the venerable Coilable boom, has been developed for the Gravity and Extreme Magnetism SMEX (GEMS) X-ray polarimetry mission led by the NASA-Goddard Space Flight Center (GSFC). The driving requirements for the TOB are precision deployment repeatability and thermal stability, as well as deployed stiffness. Achieving these requirements would be challenging with any deployable structure, but GEMS adds the constraint that the boom fit around the optical fields of view while staying within the very limited Pegasus-class launch vehicle shroud volume and mass allocation. Given these challenges, the GEMS project has funded the development of the 0.85 m diameter, 4 m long, carbon fiber Coilable TOB, through several iterations of engineering and test hardware. This development effort has succeeded in validating the performance requirements for GEMS. Copyright © 2011 by Michael McEachen.
Sanders J.T.,ATK Aerospace Systems
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014
The paper will discuss recent work at ASTM and IEST to update existing standards and introduce new standards. Committee work on standards of interest to contamination control engineers will be discussed. IEST-STD-CC1246E was released in the last year, and changes from revision D will be highlighted. A new ASTM Standard Practice for Spacecraft Hardware Thermal Vacuum Bakeout will also be emphasized. © 2014 SPIE.