Handling Lighting and Other Weather Nuisances
April / May 2008
Volume 6 Number 2
Mark Twain once said, "Everyone talks about the weather but nobody does anything about it." Well, that's still true, but at least weather forecasting these days is right far more often than it is wrong. It has, thankfully for those of us living in Florida, become a much more exact science. Which is just as well since central Florida leads the nation in lightning strikes and Cape Canaveral Air Force Station and NASA's John F. Kennedy Space Center lie within "Lightning Alley." This does not bode well if you are trying to launch space vehicles.
However, thanks to many new or improved technologies, NASA can now launch knowing it has the latest in technological information in order to keep its personnel, hardware and facilities safe.
Over the course of its history, NASA has transferred technology using a variety of methods: licensing, partnerships with industry, and infusing technology into its mission by the SBIR and STTR programs. However, the most pure form of technology transfer, and by that we mean the technology is usually published or put on a web site free of charge, is done by a little known office deep within the Applied Technology Directorate at Kennedy—€”the NASA Kennedy Space Center Weather Office. What may not be common knowledge to those of us outside of the weather community is that NASA and, in particular the space center, has made many important discoveries in the area of meteorological science and developed ground-breaking meteorological instrumentation systems.
The ability to apply these discoveries and technologies immediately to operations is due, in no small part, to the Applied Meteorology Unit (AMU), a unique concept and venture that was conceived by a NASA advisory panel and the National Research Council and established in 1991. The AMU is responsible for developing, evaluating, and transitioning technology to operations to improve weather support to spaceport operations and its customers.
The AMU's methodology for effective technology transfer relies on three key elements:
—€ Tasking is assigned by the customers with input from other stakeholders.
—€ Performance of each tasking continuously involves the customers with quarterly reviews in depth for every project.
—€ Customers review and test the resulting products before they are delivered.
The AMU's tasking process has been listed as a best practice by the Navy's Best Manufacturing Practices Institute and deserves a more detailed description. The AMU may be tasked through any of three processes:
—€ formal prioritized tasking
—€ option hours tasking
—€ mission immediate tasking.
Formal prioritized tasking accounts for over 80 percent of the AMU's workload; option hours tasking accounts for most of the remainder; and mission immediate tasking is rare, but can be of the highest priority when it occurs.
Formal prioritized taskings are assigned by consensus of the AMU tasking group. The group consists of representatives from NASA, and the agencies providing operational weather support to NASA—€”the Air Force and National Weather Service.
Six weeks prior to the quasi-annual face-to-face tasking meeting, each agency submits proposed tasks for the next 12 to 15 months.
After the proposals are received, the AMU contractor reviews and independently assesses each task for its feasibility, for its appropriateness and for the resources required to perform the task. The contractor reviews are provided to the three agencies for discussion and evaluation. The tasking meeting is designed to match the proposed work to the available resources. Inevitably, the resources required to do all the proposed work exceed the resources actually available. Unless proposals are modified or withdrawn, they must be prioritized and only those proposals with high enough priority to remain above a resource-determined "cut line" will be performed.
There are four phases of discussion at the meeting.
—€ Phase One: Each agency presents its proposals and the group asks clarifying questions. The goal is to ensure every proposal is completely understood. The proposals are not critiqued or prioritized.
—€ Phase Two: Each agency critiques the proposals and suggests eliminating, modifying or combining proposals in order to get within the resource limitation.
—€ Phase Three: If phase two does not reduce the proposed workload to match the labor available, the remaining proposals are ranked in priority order by a consensus process. If consensus is not reached, a formal vote will be conducted.
Since its inception, the AMU tasking process has always achieved a consensus result, usually by additional modification or withdrawals of proposals to get within the resource limitation. The AMU contractor is an important contributor to finding ways of re-scoping and scheduling the work to maximize the opportunity to meet the requirements of all customers. After the proposals are ranked, the contractor presents a final analysis of the remaining tasks and advises where the cut line, if any, must be drawn.
—€ Phase Four: The tasks above the line are formally adopted as the AMU's prioritized work for the following year.
Option hours tasking is available for work that was not accepted through the formal prioritized process or which is proposed between tasking meetings. A customer who is willing to pay for the service may request that their proposed task be undertaken using option hours. Under the terms of the AMU contract, the government may buy up to two full-time equivalents (FTE) per year in addition to the five FTE base-funded by NASA. The use of option hours is subject to the following constraints:
On rare occasions, the AMU's special expertise and experience may be needed to assist operational customers with a situation outside their normal experience base under conditions where there is not time to go through either of the above processes. This may happen, for example, during a launch countdown where unusual radar signatures are seen or remote sensing and in situ observations appear inexplicably inconsistent. Resolving the causes of these anomalies needs to be done immediately to assure mission success.
The success of the AMU's processes for technology transition is demonstrated three ways:
—€ AMU customers have continued to fully fund and support the AMU for 17 years despite serious challenges to their available resources
—€ The quality of work has warranted publication in numerous peer-reviewed journal articles including a cover article in the Bulletin of the American Meteorological Society
—€ The products are in daily operational use supporting the space program. Here are two examples of these products:
Lightning is a major threat to the launch or landing of space vehicles. An Anvil Forecast Tool was developed to formulate a capability to display a thunderstorm anvil threat corridor on a satellite image. An anvil is that often wispy, flat, long cloud that blows off the top of thunderstorms at high altitudes. It is generally of little concern to anyone unless they plan to fly through it. Flying through an anvil can be dangerous because the anvil may contain enough electric charge from the parent thunderstorm to trigger a lightning strike to the vehicle flying through it. The threat corridor is based on observed data or forecast data from a numerical weather prediction model.
The AMU delivered a product that allowed the forecaster to generate and display the anvil threat corridor as dotted lines overlaid on the latest satellite picture. If thunderstorms are forecast to occur in the threat corridor, the time until the resulting anvils would approach close enough to violate launch or landing lightning safety constraints can be estimated from the dotted range rings on the threat corridor overlay. By developing this tool specifically for the operational display system, the AMU enabled the forecasters to use the capability in real-time on a system they use routinely in support of daily operations and to display the anvil corridor to their customers.
Upper air wind changes are another major threat to the safety of launch vehicles as they ascend. Marshall Space Flight Center developed a radical improvement to signal processing that allowed those winds to be measured using a radar wind profiler located at Kennedy. The data from the new profiler algorithm was as accurate as the most accurate wind-finding weather balloon and better than any previously available commercial signal processing methodology for profilers. In addition, the new algorithm enabled the profiler to generate complete wind profiles from 6,000 to 60,000 feet in 500-foot intervals every five minutes. The best previously available algorithm required at least 30 minutes per profile. Balloons take an hour to generate a wind profile.
Unfortunately, MSFC's new algorithm required more computational power than was available and could only be used for research purposes because it could not be run in real-time. The AMU redesigned the software to run on the operational system in real time, developed a user interface for interactive quality control on day of launch, and wrote a comprehensive training package to enable operational personnel to effectively use these new tools. Operational use of the Kennedy wind profiler, running the AMU software and quality control interface, has already prevented loss of at least one expendable launch vehicle mission due to last-minute wind changes undetected by the weather balloons.
Carol Anne Dunn is a project specialist in the technology programs and partnerships branch and Francis Merceret is chief, Applied Meteorology Unit at the NASA Kennedy Space Center.
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