Search NASA⌕ Search

Engineering topics

McCollum, Matthew B.

Publications and source records attributed to McCollum, Matthew B..

5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

NASA Manned Launch Vehicle Lightning Protection Development

Historically, the National Aeronautics and Space Administration (NASA) relied heavily on lightning avoidance to protect launch vehicles and crew from lightning effects. As NASA transitions from the Space Shuttle to the new Constellation family of launch vehicles and spacecraft, NASA engineers are imposing design and construction standards on the spacecraft and launch vehicles to withstand both the direct and indirect effects of lightning. A review of current Space Shuttle lightning constraints and protection methodology will be presented, as well as a historical review of Space Shuttle lightning requirements and design. The Space Shuttle lightning requirements document, NSTS 07636, Lightning Protection, Test and Analysis Requirements, (originally published as document number JSC 07636, Lightning Protection Criteria Document) was developed in response to the Apollo 12 lightning event and other experiences with NASA and the Department of Defense launch vehicles. This document defined the lightning environment, vehicle protection requirements, and design guidelines for meeting the requirements. The criteria developed in JSC 07636 were a precursor to the Society of Automotive Engineers (SAE) lightning standards. These SAE standards, along with Radio Technical Commission for Aeronautics (RTCA) DO-160, Environmental Conditions and Test Procedures for Airborne Equipment, are the basis for the current Constellation lightning design requirements. The development and derivation of these requirements will be presented. As budget and schedule constraints hampered lightning protection design and verification efforts, the Space Shuttle elements waived the design requirements and relied on lightning avoidance in the form of launch commit criteria (LCC) constraints and a catenary wire system for lightning protection at the launch pads. A better understanding of the lightning environment has highlighted the vulnerability of the protection schemes and associated risk to the vehicle, which has resulted in lost launch opportunities and increased expenditures in manpower to assess Space Shuttle vehicle health and safety after lightning events at the launch pad. Because of high-percentage launch availability and long-term on-pad requirements, LCC constraints are no longer considered feasible. The Constellation vehicles must be designed to withstand direct and indirect effects of lightning. A review of the vehicle design and potential concerns will be presented as well as the new catenary lightning protection system for the launch pad. This system is required to protect the Constellation vehicles during launch processing when vehicle lightning effects protection might be compromised by such items as umbilical connections and open access hatches.

McCollum, Matthew B.↗
NASA NTRS1999

Coupling Factor Determination in the Control of Unintentionally Generated RF Fields

Radiated emissions and susceptibility requirements imposed in bands where intentional RF reception or transmission does not occur is problematical. It is often desired to compare radiated emissions with radiated susceptibility performance to assess system level compatibility. For reasons purely theoretical and because of practical measurement limitations, this not realistic. McCollum and Clark proposed a limit and test method that provided a direct comparison of radiated emissions and radiated susceptibility performance in those cases where only unintentional emissions and reception are of interest (non-tunable electronics). This test method, referred to as bulk current emissions (BCE) testing, and its associated limit is a complementary test method to bulk current injection testing and radiated susceptibility testing. Previous work utilized victim and culprit circuits with low common-mode loop impedance. Forward work identified in this publication was to determine how different loop impedance on culprit and victim circuits affected cable-to-cable coupling and the corresponding BCE test limit. Cable coupling factors for victim and culprit circuits with different loop impedance are investigated.

McCollum, Matthew B.↗
NASA NTRS1997

TSS-1R Failure Mode Evaluation

Soon after the break of the tether during the Tethered Satellite System (TSS-1R) mission in February, 1996, a Tiger Team was assembled at the George C. Marshall Space Flight Center to determine the tether failure mode. One possible failure scenario was the Kevlar' strength member of the tether failed because of degradation due to electrical discharge or electrical arcing. During the next several weeks, extensive electrical discharge testing in low vacuum and plasma environments was conducted in an attempt to reproduce the electrical activity recorded by on-board science instruments during the mission. The results of these tests are presented in this paper.

Vaughn, Jason A.↗