Phillip D. Anz-Meador

Bio: Phillip D. Anz-Meador is an academic researcher from Jacobs Engineering Group. The author has contributed to research in topics: Space debris & Debris. The author has an hindex of 10, co-authored 38 publications receiving 792 citations.

Orbital Debris Environment for Spacecraft Designed to Operate in Low Earth Orbit

Abstract: The orbital debris environment model is intended to be used by the spacecraft community for the design and operation of spacecraft in low Earth orbit. This environment, when combined with material-dependent impact tests and spacecraft failure analysis, is intended to be used to evaluate spacecraft vulnerability, reliability, and shielding requirements. The environment represents a compromise between existing data to measure the environment, modeling of this data to predict the future environment, the uncertainty in both measurements and modeling, and the need to describe the environment so that various options concerning spacecraft design and operations can be easily evaluated.

The New NASA Orbital Debris Engineering Model ORDEM2000

Abstract: The NASA Orbital Debris Program Office at Johnson Space Center has developed a new computer-based orbital debris engineering model, ORDEM2000, which describes the orbital debris environment in the low Earth orbit region between 200 and 2000 km altitude. The model is appropriate for those engineering solutions requiring knowledge and estimates of the orbital debris environment (debris spatial density, flux, etc.). ORDEM2000 can also be used as a benchmark for ground-based debris measurements and observations. We incorporated a large set of observational data, covering the object size range from 10 mm to 10 m, into the ORDEM2000 debris database, utilizing a maximum likelihood estimator to convert observations into debris population probability distribution functions. These functions then form the basis of debris populations. We developed a finite element model to process the debris populations to form the debris environment. A more capable input and output structure and a user-friendly graphical user interface are also implemented in the model. ORDEM2000 has been subjected to a significant verification and validation effort. This document describes ORDEM2000, which supersedes the previous model, ORDEM96. The availability of new sensor and in situ data, as well as new analytical techniques, has enabled the construction of this new model. Section 1 describes the general requirements and scope of an engineering model. Data analyses and the theoretical formulation of the model are described in Sections 2 and 3. Section 4 describes the verification and validation effort and the sensitivity and uncertainty analyses. Finally, Section 5 describes the graphical user interface, software installation, and test cases for the user.

Orbital Debris Quarterly News

Abstract: The Indian spacecraft Microsat-R (International Designator 2019-006A, U.S. Strategic Command [USSTRATCOM] Space Surveillance Network [SSN] catalog number 43947), launched on 24 January 2019, was intentionally destroyed in a test of a ground-based, direct-ascent Anti-Satellite (ASAT) weapon system at 0640 GMT on 27 March 2019. At the time of breakup the 740 kg spacecraft was in an approximately 294 x 265 km altitude, 96.63° orbit. A total of 101 debris have entered the public satellite catalog (through object 2019-006DF), of which 49 fragments remain on-orbit as of 15 July 2019. However, over 400 fragments were initially tracked by SSN sensors and cataloging is complicated by the low altitude of the event and the concomitant rapid orbital decay. A Gabbard plot of this debris cloud is presented in the figure on page 2. A Centaur V Single-Engine Centaur (SEC) rocket variant (International Designator 2018-079B, SSN number 43652) fragmented in early April 2019. At the time of the event the stage was in an approximately 35,092 x 8526 km altitude, 12.2° orbit. This Centaur V upper stage is associated with the launch of the USA 288, or Advanced Extremely High Frequency 4 (AEHF 4), spacecraft from the (U.S.) Air Force Eastern Test Range on 17 October 2018. The cause of the event is unknown. No debris have entered the catalog at this time, but the ODQN will provide updates should they become publicly available.

Critical number of spacecraft in low Earth orbit: using satellite fragmentation data to evaluate the stability of the orbital debris environment

Abstract: Previous studies have concluded that fragments from random collisions in low Earth orbit will cause the orbital debris population to increase despite efforts to minimize the accumulation of debris. New data from the orbital history of fragments in space and the laboratory hypervelocity breakup of a payload more accurately confirms this conclusion. The conclusions are reached that the orbital debris environment for much of low Earth orbit is unstable and will seek a higher equilibrium even if no new debris is added to the environment. Some regions may be slightly above a runaway level, where no equilibrium is possible as long as the number of intact objects remains constant. The rate of increase for collision fragments is currently low, but would increase rapidly with increases in the intact population.

Risks in Space from Orbiting Debris

Abstract: 340 C R E D IT : (T O P ) N A S A S ince the launch of Sputnik I, space activities have created an orbital debris environment that poses increasing impact risks to existing space systems, including human space flight and robotic missions (1, 2). Currently, more than 9000 Earth-orbiting man-made objects (including many breakup fragments), with a combined mass exceeding 5 million kg, are tracked by the U.S. Space Surveillance Network and maintained in the U.S. satellite catalog (3–5). Three accidental collisions between catalogued objects during the period from late 1991 to early 2005 have already been documented (6), although, fortunately, none resulted in the creation of large, trackable debris clouds. The most recent (January 2005) was between a 31-year-old U.S. rocket body and a fragment from the third stage of a Chinese CZ-4 launch vehicle that had exploded in March 2000. Several studies conducted during 1991–2001 demonstrated, with assumed future launch rates, the potential increase in the Earth satellite population, resulting from random, accidental collisions among resident space objects (7–13). In some low Earth orbit (LEO) altitude regimes, where the number density of objects is above a critical spatial density, the production rate of new debris due to collisions exceeds the loss of objects due to orbital decay. LEGEND (LEO-to-GEO Environment Debris model), is a highfidelity three-dimensional physical model developed by the U.S. National Aeronautics and Space Administration (NASA) that is capable of simulating the historical environment, as well as the evolution of future debris populations (14, 15). The LEGEND future projection adopts a Monte Carlo approach to simulate future onorbit explosions and collisions (16). A total of 50 (17), 200-year future projection Monte Carlo simulations were executed and evaluated, under the assumptions that no rocket bodies and spacecraft were launched after December 2004 and that no future disposal maneuvers were allowed for existing spacecraft (few of which currently have such a capability) (18). The simulated 10-cm and larger debris populations in LEO (defined as the region between altitudes of 200 and 2000 km) between 1957 and the end of a 200-year future projection period

Advances in Polyimide-Based Materials for Space Applications.

Abstract: The space environment raises many challenges for new materials development and ground characterization. These environmental hazards in space include solar radiation, energetic particles, vacuum, micrometeoroids and debris, and space plasma. In low Earth orbits, there is also a significant concentration of highly reactive atomic oxygen (AO). This Progress Report focuses on the development of space-durable polyimide (PI)-based materials and nanocomposites and their testing under simulated space environment. Commercial PIs suffer from AO-induced erosion and surface electric charging. Modified PIs and PI-based nanocomposites are developed and tested to resist degradation in space. The durability of PIs in AO is successfully increased by addition of polyhedral oligomeric silsesquioxane. Conductive materials are prepared based on composites of PI and either carbon nanotube (CNT) sheets or 3D-graphene structures. 3D PI structures, which can expand PI space applications, made by either additive manufacturing (AM) or thermoforming, are presented. The selection of AM-processable engineering polymers in general, and PIs in particular, is relatively limited. Here, innovative preliminary results of a PI-based material processed by the PolyJet technology are presented.