Part of a Day's Work: Notable Contributions by Aerospace Personnel

Each year, Aerospace bestows a number of awards that encourage, commend, and reward significant contributions of individuals and project teams that go far beyond normal expectations. The Trustees' Distinguished Achievement Award is the most prestigious of these awards, acknowledging work of the highest caliber as determined by a panel of judges representing all facets of the Aerospace professional community. Collectively, these awards present a window into the inner workings of Aerospace, providing insight into the sort of projects that are pursued and the sort of results that can be achieved. Here, then, are the past five winners of the Trustees' Distinguished Achievement Award, describing in their own words their contributions to the national security space community.

Joseph A. Anselmi (2004)

Recipients of the Trustees' Award are usually honored for a single, major event, project, or capability. My award was for multiple contributions considered collectively, so I will highlight only a few of them. These contributions derived from my primary responsibility, heading up the independent stability and control analysis (ISACA) effort on the current three generations of GPS spacecraft. This activity involves independently developing all spacecraft sensor, actuator, and vehicle dynamic models, combining them with attitude-control flight software, and simulating and testing all aspects of the spacecraft's flight regime to assess performance and stability.

The program office decided to fund the ISACA effort for all future generations of GPS after several instances of instability on orbit with the first generation of GPS spacecraft. A major outcome of the ISACA effort is the development of a real-time hardware-in-the-loop simulation that operates with actual flight software executing on the actual or equivalent spacecraft processor. Currently, there are three of these simulators for the GPS Block II/IIA, Block II/IIRM, and Block IIF spacecraft.

Joseph Anselmi

The development and use of these real-time simulators requires a team of specialists. Their work involves flight software validation and testing, software and hardware simulation interface design, redundancy management testing and development, and on-orbit anomaly support. I am fortunate to have the support of an extremely talented team that includes Rita Meistrell, Chul Kim, S. L. Chow, and Kamran Aslam.

The simulators have pinpointed a variety of problems. For example, I found an incipient instability involving the Block II/IIA spacecraft when one of the reaction wheels failed. The program office was warned, and when the condition later occurred on orbit, procedures we developed to correct the problem were successfully implemented. Two other spacecraft missions were extended because of contingency procedures developed by our team using the Block II/IIA simulator.

Testing the Block IIR spacecraft uncovered 58 flight software discrepancies and five specific control-system instabilities that the contractor had to correct prior to flight. Four of these instabilities would not otherwise have been found until the spacecraft was on orbit, placing the mission at risk.

The high-fidelity dynamics of our Block IIR simulator enabled us to simulate the Earth-acquisition sequence while one of the secondary payload antennas was deployed. This was a procedural change necessitated by a thermal constraint. The contractor's simulation was incapable of this complicated maneuver. Thus far, a total of 75 software patches have been developed for GPS Block IIR. No patch is uploaded to the spacecraft until it has been thoroughly validated and tested by our team using the simulator.

Our testing of the Block IIF spacecraft software found several problems in the eclipse control and a weakness in the yaw turning maneuver during the spacecraft's operation in low sun elevation regions. These problems were brought to the attention of the contractor for resolution.

The spacecraft contractors strive to prove that their spacecraft-control laws perform to expectations and are stable with adequate control margins. Our ISACA testing strives to discover weaknesses or inadequacies in their control laws. The interplay between these two philosophies produces an improved design that not only meets but exceeds expectations. Our real-time simulators are used for extensive testing prior to launch, for supporting launch activities, and for assisting anomaly investigations. They are also used to train the Aerospace and Air Force early orbit support teams.

The real-time simulation capabilities have provided the Aerospace and Air Force Program Offices an independent validation of the adequacy of these three GPS spacecraft's control system designs prior to launch. They have supported investigation of numerous on-orbit anomalies, and in general contributed to a more robust spacecraft design for the GPS worldwide community. These achievements have enabled the ongoing constellation sustainment effort to make efficient use of the older on-orbit spacecraft that have been kept operating well beyond their design lives.

Wayne Stuckey (2003)

"A satellite operating in what is generally considered to be the vacuum of space might seem to be in a friendly environment, but it is actually a hostile environment for the materials on the exterior surfaces of a spacecraft." That is the opening sentence of an article authored by me and Michael Meshishnek for the Summer 2003 issue of Crosslink. It sums up our need to understand the space environment and its impact on spacecraft materials, which was a primary focus in my work at Aerospace. The degradation of the materials on a satellite may shorten its useful lifetime in orbit, so it is obviously important to know which materials provide the best stability and durability.

Wayne Stuckey

Our knowledge of the stability of spacecraft materials comes from experience with previously launched satellites and from testing programs. In some cases, we have been able to study materials returned from space. The space shuttle, for example, allowed us to study materials with our colleagues at NASA and in industry in several ways. Early shuttle flights revealed the importance of atomic oxygen reactions in the low Earth environment; that awareness led to experiments on materials in the shuttle bay during some missions. The shuttle also allowed the deployment of the Long Duration Exposure Facility (LDEF) in a low Earth orbit and its retrieval nearly six years later. Extremely useful data were obtained for thousands of materials in that environment. No materials have ever been returned from the higher orbits, but we often obtain flight data from those orbits that we can use to learn about material stability. It's hoped that future opportunities will return samples to Earth from higher orbits.

These investigations have also provided a check on the ground-based testing that is conducted on environmental stability of spacecraft materials. Although we have data on the performance of materials in low Earth orbit, we must rely on ground testing to know about materials in higher orbits and to evaluate new materials or processing changes during materials manufacture. Our capability to perform these tests has increased significantly in recent years and, in some cases, the results from these tests may be the only data available on the stability of a material for a particular satellite program.

The knowledge gained from flight experience and ground testing is the basis for evaluating the environmental stability of a spacecraft material. It allows us to identify poor selections of materials and to avoid materials that would have degraded in the intended application and affected satellite lifetimes. That knowledge also allows us to recommend or confirm acceptable alternatives. Selection of acceptable materials is one of the factors that contribute to achieving mission success in national space programs.

William Feess (2002)

My award was for the work I have performed in support of the navigation mission of the GPS program. This is a brief history of my association with the program and some of my work since I began working on GPS in 1970, when it was called Program 621B. I was a member of the core team that defined the initial GPS.

Flight tests at White Sands, using four ground transmitters, supported the signal structure and the aircraft navigation concepts, and in 1973 the program got the go-ahead for the satellite phase of the program. I supported the proposed evaluation for the ground and satellite phases. Atomic clocks are the heart of the GPS system, and during this period I analyzed their performance characteristics and the role they played in satellite orbit determination and prediction.

William Feess

Problems were encountered in the early launches affecting the accuracy of the satellite orbit estimation and prediction. The first of these involved the management of the spacecraft moment wheels. Initial design was to dump (despin) the momentum wheels using balanced thrusters. Exhaust plume impingement caused unplanned perturbation to the orbit and the navigation mission of GPS. Once recognized as a problem, the management of wheel dumping was changed to application of magnetic moments. Another problem involved the model for solar pressure forces. Yaw-attitude and solar-panel misalignments caused the forces to be misaligned with respect to the model being used for the orbit determination. To compensate for misalignments, a "Y bias" parameter was introduced in the estimation process. To this day, the "Y bias" parameter is part of the orbit estimation process.

The models for compensating the relativity effects on clocks had been a big issue during the 1980s. I worked on that particular aspect of the problem and, using pseudo-ranging data, demonstrated that the equations being used are correct for satellite-to-ground measurements, but also correct for satellite-to-satellite measurements. As clocks become more accurate, the relativity theory may have to be revisited, and additional terms may be necessary to achieve the full benefits of improved clocks. However, for now the models and implementation are adequate.

Throughout the 1980s, my work was associated with analyses using flight data to support system navigation accuracy performance. Also, requirements were being formulated for system survivability without ground support. Analyses showed that if we would implement crosslink measurements using the UHF com link, we could implement onboard software to do the orbit determination and prediction navigation problem. This led to implementation of Autonav (Autonomous Navigation) on the Block IIR and the next generation, Block IIF. We also took parts of the concept and applied them in Autonomous User and Survivable User Concepts. These were tested in Washington, DC, Adelaide, Australia, and Tromso, Norway.

It was in the 1990s that the system achieved operational status. During that time, we studied methods for improved accuracy and one of the initiatives was funded—the Accuracy Improvement Initiative (AII)—to be operational before the end of the century. The first Block IIR (replacement for the aging Block IIs) satellite, with improved satellite clocks, was launched. Analysis of the data demonstrated that its performance was better than twice the specification and four times better than the Block II satellites. This motivated "what if" studies. Simulations of a full constellation of improved clocks showed the superior performance to be expected. Also, if predictions could be made and disseminated more often, a significant improvement would result. We analyzed use of crosslinks to perform this function.

Some of the activities being supported in this new century relate to the next generation of GPS satellites, Block IIIs. We briefed the contractors on current and projected performance of the system. We also looked at using improved crosslinks for Autonav and dissemination of current filter states of the ground filter. Applications using GPS in orbit determination of LEO to GEO satellites have been performed to demonstrate the accuracy to be expected.

Integrity of the GPS signals has become increasingly important as the use expands. To this end, we have been working with the Jet Propulsion Lab and its worldwide network of stations to monitor the signals for performance and anomalies. It is planned to have this, an independent monitor, made available to the system operators.

Of course, I would not have received this prestigious award without the dedicated support from the nomination committee and especially program office personnel. I wish to thank them for that.

Peter J. Carian (2001)

My work in resolving the Defense Satellite Communications System (DSCS) separation timer anomaly was recognized by the Trustees' Award in 2001. When power was applied before launch to the DSCS III-B11 satellite atop its booster, the satellite unexpectedly started its postseparation initialization timer. This mysterious problem almost caused the launch to be scrubbed and the DSCS satellite destacked from the launch vehicle and returned to the factory. The contractor made a thorough effort but could not resolve the problem. Adding to the confusion was a thunderstorm that had passed through the area the previous evening and some rain seepage onto the spacecraft that some thought might be the source of the problems.

I quickly gathered circuit drawings of the spacecraft's power system, the ground equipment interface diagram, and the launch vehicle separation circuitry, then taped them together to form an end-to-end picture of the situation. The next day I traveled to the contractor's facility in Sunnyvale to inspect a sister satellite and talk with design engineers. The following day, I flew to the launch base, where I assembled a comprehensive time line that showed the entire problem history—for each event, what happened and when it happened.

These diverse information sources provided the critical perspective that I needed to recognize the relationship between fault-tolerance circuits in the separation sequencer added to allow launch from the space shuttle, the slightly off-nominal power-up sequence, and the response of the satellite separation initiation timer.

Peter Carian

An insight came to me at lunch that day. It enabled me to sketch out (on a bar napkin!) the essence of the cause-and-effect sequence of events that the launch community had been searching for and thus diagnose the problem. Verifying my conclusions with circuit simulation, I devised a series of confirmation tests that were performed the following day. Those tests convinced the program director that continuing the launch would be safe.

Resolution of the DSCS separation timer anomaly resulted in substantial cost savings (millions of dollars) for the program and avoided the elaborate formal investigation, including congressional inquiries, that would have resulted from a significant launch delay.

Since joining The Aerospace Corporation in 1980, I have supported spacecraft avionics by reviewing designs, resolving anomalies, and assessing risk for program offices, customers, contractors, and NASA. Over the years, I have received more than 60 letters of commendation, awards, and citations for this work. DVD copies of my presentation "Engineering on a Napkin—An Award-Winning Perspective on Mission Success" are available from The Aerospace Corporation's Lauritsen Library.

Joseph F. Wambolt (2000)

The Trustees' Award presented to me in 2000 was in recognition of sustained effort for Aerospace management of the very successful Medium Launch Vehicle Program, which included the Delta II, Atlas II, and refurbished Atlas E/F ICBMs into space launch vehicles.

I have been Principal Director of the Western Range Directorate at Vandenberg Air Force Base (VAFB) since 1999. Meeting the challenges of adapting to a new organization and establishing working interfaces with the VAFB 30th Space Wing and base contractors has been a rewarding and pleasant experience. The focus on mission success is highly magnified in this operational setting, as the actual flight hardware and the people who prepare the launch vehicles, satellites, and range support are highly visible every day.

Joseph Wambolt

"Team VAFB" has successfully launched all the remaining heritage Titan II and Atlas IIAS missions, with the last remaining Titan IV launch planned for this summer. Meanwhile, launch facility reconstruction to accommodate the new Delta IV and Atlas V families of Evolved Expendable Launch Vehicles has given me and the local Aerospace team great opportunities to provide technical contributions to the building and activation of Space Launch Complex 6 and Space Launch Complex 3E. Several of the Aerospace engineers at Vandenberg had been involved in the original design and construction of these launchpads. Valuable drawings, calculations, and lessons learned have been retrieved and provided to the contractors.

We are also currently assisting the 30th Space Wing Launch Group in planning launch sites and operations scenarios for operationally responsive launch initiatives under consideration by Air Force management, and observing the testing of range modernization equipment to be used in future missions by the 30th Space Wing Operations Group.

I believe the past five years have given me personally many new gratifying learning opportunities to assist our DOD customers in achieving mission success for existing and future missions.

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