Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Earth science
Reexamination Certificate
1999-02-19
2001-01-16
Oda, Christine (Department: 2862)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Earth science
C324S072000
Reexamination Certificate
active
06175808
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to the field of lightning-induced transients monitoring. More particularly the invention relates to sensory input processing for the detection of potentially damaging lightning strikes on various systems.
BACKGROUND OF THE INVENTION
Launching space vehicles into space from locations of high frequency of lightning strikes, such as in Florida, presents a recurring problem and concern of the potential lightning induced damage to the space vehicles and payload systems prior to launch. This concern is especially acute for launches taking place during the high lightning season in the summer months. Those involved in the actual launch activities must account for the chaotic atmosphere particularly when a nearby lightning strike has been reported during the critical time path just before a launch. Currently, the assessment of the potential damage to the launch and space vehicle mainly depends on limited and primitive means. The entire launch vehicle including the payload, space vehicle, and an upper stage, if required, are subject to precautions offering modest protection against lightning, often without accurate knowledge of the threat. The decision to proceed with normal launch activities or to switch to retest and re-certification procedures is a difficult one which is subject to conjecture and often results in over-testing or under-testing. As more and more sensitive devices are used in the space vehicles and in order to achieve a balance between too much retest and too little retest, a more reliable lightning retest criterion to help make a real-time decision is needed. The purpose of such a criterion is, on the one hand, to avoid unnecessary and costly tests and delays, and on the other hand, to avoid launching damaged or degraded vehicles and payloads into space.
In order to effectively protect against lightning-induced electromagnetic effects, it is prudent to monitor and then protect selected lines and devices. There are two types of known lightning monitoring systems. One type of monitoring system is a remote off-line sensing system that measures the lightning current in the distant lightning channel. Another type of monitoring system is a proximal on-line monitoring system that measures direct parameters that stress the launch system and payload. One on-line monitoring system is the transient pulse monitoring system and has been used during Air Force launches. The proximal on-line monitoring system supports real-time launch operations. Ideally, the on-line monitoring system should be able to provide readings at as many sensor locations as needed. The initial placement of the sensors is guided by analyses for severe field points, that is, major entry points for lightning energies along critical and sensitive penetration paths. The present transient pulse monitoring system can only provide readings at six locations external to the space vehicle. High and low limits for sensors are used to start printed recorders or to alert the launch director based on external stress estimates that need to be refined to correlate with the internal stress at the circuit level. Flow-down analyses are needed to propagate the external stress to the internal circuits, followed by circuit coupling analysis and susceptibility analysis. Ideally, some internal circuit lines can be monitored to provide direct readings at the circuit level eliminating some of the simplifying assumptions and uncertainties in the mathematical models of the analyses. The present transient pulse monitoring system provides three types of stress readings including sheath current readings on the umbilical cable reading, electric field readings on selected surfaces, and magnetic field readings above the umbilical cable. Each type of reading presents a different mode of entry for the lightning energy coupled into the space vehicle system. These readings must be coordinated to give a combined indication of the stress at the circuit level.
The present Launch Range-operated cloud-to-ground lightning surveillance system is a remote sensing system. While it is valuable for general weather forecast purposes, it provides only indirect cloud-to-ground data of unspecified effects on the system circuits. To translate the distant environmental lightning data into system-specific stress data, many contractors at the present time rely on analyses that are quasi-static and back-of-the-envelope types of estimates for simple, now-obsolete launch configurations. Other existing monitoring systems are even more primitive having low fidelity and resulting in low confidence level information about lightning-induced transients that have resulted in many unnecessary retests and delays. Recent events have made many contractors aware of these limitations, and have moved them to use the proximal on-line monitoring system, and to re-examine their retest criteria.
The existing proximal on-line lightning monitoring systems use either analog or digital technology for detection and data processing. Currently two types of direct on-line lightning monitoring systems have been fielded. An analog type system, such as the transient pulse monitoring system, performs analog peak detection during continuous monitoring of lightning-induced transients. The digital monitoring system provides detailed waveform information of the transients. When deployed alone, the analog monitoring system gives no actual waveforms, while the digital monitoring system may miss significant events due to sampling limitations. The analog monitoring offers continuous front-end monitoring but lacks the actual waveform details that are needed and used by many contractors. It should be advantageous and cost-effective to combine these analog and digital systems into one integrated hybrid system that would avoid these shortfalls.
A correct determination of a Go and No-Go evaluation is vital to the launch operation that has obvious consequences on mission success. An efficient and effective retest algorithm is desired. The present-day algorithms used by contractors are based on the Boolean logic, indirect parameters, and inadequate measurements that often result in over-testing or under-testing. Over-testing leads to unnecessary delays, higher cost, and schedule impacts, while under-testing is dangerous because damage may not be discovered, resulting in the launch of a defective vehicle into space where no repair is feasible. Under-testing is most dangerous in that damage will not be discovered and damaged vehicles may be launched.
The miniaturization of electronic devices makes the launch system more sensitive and vulnerable to lightning-induced electromagnetic transients. Therefore, many systems have implemented procedures, often called lightning retest criteria or lightning damage search criteria for their launch processing operations following major lightning storms. Many existing lightning retest criteria and lightning damage search criteria are based on indirect parameters. This results in simplistic, misleading and erroneous retest decisions. During the critical moments shortly before launch, little time is allowed for detailed and elaborate analysis of the situation that may arise due to lightning events. However, many complicated analyses are generic processes that can be performed well in advance of a launch, and the analytical results with appropriate system configurations can be incorporated into the lightning effects evaluation algorithm in the form of lookup data tables.
Instead of waiting for nature to deliver all types of lightning over a long period of time, parametric studies using mathematical models can be carried out to analyze many possible scenarios. Three kinds of analyses are needed to support the formulation of a dependable lightning retest evaluation method. The three kinds of analyses are electromagnetic (EM) field coupling analysis, circuit coupling analysis, and susceptibility analysis. These analyses can be performed during pre-launch periods.
Field coupling analysis is an EM field coupling analysis that is based on the
Oda Christine
Reid Derrick Michael
Taylor Victor J.
The Aerospace Corporation
LandOfFree
Lightning effects monitoring and retest evaluation method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Lightning effects monitoring and retest evaluation method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lightning effects monitoring and retest evaluation method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2507603