The www.orbitaldebris.jsc.nasa.gov

Volume 9, Issue 4 October 2005

A publication of The Orbital Debris Community Loses One of The NASA Orbital its Pioneers Debris Program Office Joseph P. Loftus, Jr., one of the most influential velopment programs, Loftus was responsible for nur- at leaders for orbital debris research in the U.S. and the turing the new technologies in thermal protection world, passed away suddenly on 4 September 2005 at systems; advanced technology for bipropellant engine Johnson Space Center the age of 75. For 25 years before his retirement design and fabrication, more efficient supercritical Houston, TX, USA from NASA in 2001, Joe, as he was universally cryogenic storage systems, higher efficiency fuel known, was the senior proponent for orbital debris cells, large area solar cells, and advanced software research at the Lyndon B. Johnson Space Center developments. (JSC) and was instrumental in the establishment of In the late 1970s Joe brought the early orbital the NASA Orbital Debris Program Office. He also debris research work of Don Kessler and Burt Cour- served in leadership roles at the Palais to the attention of senior NASA INSIDE… United Nations, the International management at JSC and NASA head- Academy of Astronautics, the Inter- quarters. Although still serving in Agency Space Debris Coordination many other leadership positions, in- Real-time Survey and Committee, and the International cluding as Assistant Director (Plans) Follow-up Telecommunication Union on matters for JSC, Loftus was known as an in- Observations related to orbital debris. ternational spokesman for the under- of GEO Debris ...... 2 Loftus completed flight training standing and mitigation of orbital in the United States Air Force in 1957 debris for the remainder of his career and was serving at Wright-Patterson at NASA. He was one of the guiding Reentry Survivability Air Force Base on zero-visibility forces in the formation of the multi- Analysis of the Terra landing systems in 1961 when the national Inter-Agency Space Debris Satellite ...... 3 U.S. embarked on the Mercury man- Coordination Committee. He also in-space program. He was quickly Joseph P. Loftus, Jr. served a leading role in the long-term assigned to work with NASA in Houston, Texas, study of orbital debris by the International Academy Progress in Space before the Manned Spacecraft Center (later JSC) was of Astronautics, in which he served for many years, Tether Sever even established. He was responsible for defining the including as Chairman of the Committee on Interna- Modeling...... 4 crew accommodations and the crew control and dis- tional Space Policies and Plans. However, he never play arrangements for the Mercury and Apollo Space- abandoned his engineering expertise and in the mid- craft. As a special task force effort, he led the design 1990s was the first to recognize the potential of elec- Abstracts from the of the systems to extend the lunar landing mission trodynamic tethers to remove derelict satellites from NASA Orbital Debris stay time from 24 to 72 hours and the complementary Earth orbit. Program Office ...... 5 extension of the total mission duration of the orbiting Loftus was the recipient of many awards, includ- command and service modules from 9 to 12 days. ing the NASA Exceptional Service Medal (twice) and During the Space Shuttle and Space Station de- the NASA Distinguished Service Medal. ‹ Space Missions and Orbital Box Score .... 9 Two NASA Spacecraft to be Retired; Debris Mitigation Plans Being Implemented In September NASA began procedures to dispose abilities. Fortunately, ERBS and UARS were still of two old spacecraft in low Earth orbit (LEO) in capable of meeting the primary guidelines of end-of- Visit the NASA accordance with the guidelines to mitigate the mission passivation and reduction of orbital lifetime. Orbital Debris Program generation of orbital debris as called for by NASA ERBS was launched by Space Shuttle Challenger Office Website Safety Standard (NSS) 1740.14. Both spacecraft, the in October 1984 and was inserted into an orbit near Earth Radiation Budget Experiment (ERBS) and the 600 km with an inclination of 57°. In 2002, when the th at Upper Atmosphere Research Satellite (UARS), were spacecraft was then nearing its 18 anniversary in launched by Space Shuttles prior to NASA’s adoption space, a series of 11 maneuvers was undertaken to www.orbitaldebris. of an orbital debris mitigation policy. However, all ensure that the spacecraft would reenter the atmos- jsc.nasa.gov older NASA missions are to comply with NSS Continued on page 2 1740.14 disposal guidelines to the best of their 1

The Orbital Debris Quarterly News Mitigation Plans Continued from page 1 orbit of approximately 500 km by 550 km phere within 25 years in the event of a sudden ERBS should fall back to Earth within 15-20 failure or its later decommissioning. This years, well within the recommended NASA, action lowered the perigee of the two-metric- U.S. Government, and international commu- ton ERBS by 60 km. The mission then nity goal of less than 25 years. continued for three more years before the The larger UARS spacecraft, with a program was selected for termination. mass in excess of six metric tons, was In September 2005, ERBS conducted deployed from the Space Shuttle Discovery three burns of its propulsion system with two in September 1991. Its orbit was very similar burns lasting five hours or more. A final to that of ERBS with a mean altitude of burn of nearly seven hours duration is slightly less than 600 km and an inclination planned in October, after which the space- of 57°. By September 2005 the spacecraft craft will be passivated. At the start of the had naturally decayed to a mean altitude of Artist’s rendering of the Upper Atmosphere Research Satellite. maneuvers, ERBS possessed more than 80 kg about 550 km. From this orbit, reentry would of propellants. Although a degradation in its be expected in a little more than 25 years. new orbital debris. During their remaining electrical power system prevented reorienting As with ERBS, beginning in October time in space, the orbits of both spacecraft the spacecraft to conduct the most efficient UARS will conduct a series of maneuvers to will be evaluated daily for potential close altitude reduction maneuvers, from its current achieve two objectives: (1) remove the 150 approaches to Space Shuttles and the kg of residual propellants to prevent future International Space Station and its logistics accidental explosions and (2) reduce the vehicles. Collision avoidance maneuvers orbital lifetime of the spacecraft to the would be undertaken in the extremely greatest extent possible. These maneuvers unlikely event that ERBS or UARS posed a should lower the perigee of UARS by more significant risk to human space flight than 200 km, leading to a natural reentry in operations. less than five years. Despite the fact that ERBS and UARS All the ERBS and UARS maneuvers are are 21 and 14 years old, respectively, to date closely coordinated with the U.S. Space spacecraft operators at NASA’s Goddard Surveillance Network to ensure that each Space Flight Center, in cooperation with the maneuver would not result in the accidental U.S. Space Surveillance Network, have been collision of the spacecraft with any other able to implement retirement plans for both Artist’s rendering of the Earth Radiation cataloged resident space object. Such a spacecraft safely and to meet key orbital Budget Experiment. collision could inadvertently create a cloud of debris mitigation objectives. ‹ PROJECT REVIEWS Real-time Survey and Follow-up Observations of GEO Debris P. SEITZER, K. ABERCROMBY, in both right ascension and declination. not just the initial five minutes. No exist- E. BARKER, H. RODRIGUEZ, This upgrade was funded by the NASA ing datasets or catalogs were used for these E. STANSBERY, M. MATNEY, Orbital Debris Program Office and the work orbits or predictions – only the data that M. HORSTMAN, & L. FOSTER was done by DFM Engineering of Long- was obtained at the telescope that night. For the past several years the Univer- mont, Colorado. For these initial tests the telescope led sity of Michigan’s 0.6/0.9-m Curtis Schmidt During three nights in July 2005 MOD- the predicted position of each object in the telescope at Cerro Tololo Inter-American EST was used for the first time in a real- sense that the object would drift across the Observatory in Chile has been used exten- time survey and follow-up mode to observe field-of-view five minutes after the tele- sively for an optical survey of debris at GEO debris. The first two hours of a scope set on the predicted position, and geosynchronous orbit (GEO). This project night’s survey data was reduced on-line at would continue to observe the field for five is called MODEST (for Michigan Orbital the telescope, and the positions and times of minutes after the object was predicted to Debris Survey Telescope), and to date has all detected objects sent to the NASA Or- have left the field-of-view. Thus we are produced purely statistical observations of bital Debris Program Office in Houston, largely insensitive to along-track errors in the GEO debris environment as reported in Texas. Within 45 minutes, preliminary the predictions. previous articles (see Orbital Debris Quar- orbits were calculated and predicted posi- A preliminary reduction showed that terly News, 9-3, p. 5 and 8-1, p. 8). tions as a function of time for the next four we were successful in recovering at least During March 2005 the telescope me- hours were forwarded to the telescope. 75% of the initial objects found. We strove chanical systems were completely modern- Upon receipt of these predictions survey to observe each object for two follow-up ized. New drives, encoders, and full com- mode was stopped and MODEST went into observations, spanning (on average) three puter control of the telescope and dome a follow-up mode to reacquire the initial hours of time from the first detection to last were installed. The telescope can now track detections. The goal is to produce much follow-up. at any commanded rate up to 1.25 deg/sec better orbits based on arcs of several hours, Continued on page 3 2 www.orbitaldebris.jsc.nasa.gov GEO Debris Continued from page 2 Figure 2 shows a zoomed region centered sumably high A/M, GEO debris to exam- Figure 1 shows our first follow-up se- on each detection. ine their orbits and how they change with quence (8 detections) on a R=16th magni- Future work will refine this technique time. ‹ tude object at a Galactic latitude of 12°. and concentrate on the orbits of faint, pre-

Figure 1. Sum of eight sequential follow-up observations of a R=16th magnitude object. The streaks are all background stars, and the red circles are centered on the detections of the object as it crosses the field-of-view (1.3° from left to right). These observations were obtained 2.3 hours after the initial detection, and were at the low Galactic latitude of 12°. A second set of follow-up observations were obtained 1.1 hours later, for a total time span of 3.4 hours of observations.

Figure 2. To show each detection better we present a zoomed region in the individual images centered on each detection. Each box is 74 x 74 arc-seconds in size. Reentry Survivability Analysis of the Terra Satellite R. SMITH, R. DELAUNE, & unprecedented measurement accuracy. At satellite into 280 different objects. J. DOBARCO-OTERO the end of its mission, the altitude of the This analysis assumed natural orbital The Terra spacecraft (1999-068A, U.S. spacecraft will be lowered to reduce its decay for the spacecraft to an altitude of Satellite Number 25994) was launched on remaining time in Earth orbit to less than 25 122 km. The parent body (seen in Figure 1) 18 December 1999 and maneuvered to an years, in accordance with NASA, U.S., and was modeled with a length of 4.0 m, a altitude of 705 km with an orbital inclina- international orbital debris mitigation width of 2.6 m, and a height of 1.8 m. A tion of 98.2°. Terra is part of the NASA guidelines. standard break-up altitude of 78 km was Earth Observing System (EOS) project to Engineers from the NASA Orbital considered, at which point all the primary study the health of the Earth by monitoring Debris Program Office were tasked by the spacecraft components were exposed to the atmosphere, oceans, and continents with Earth Science Mission Operations Project at reentry heating. In many cases, fragmenta- NASA Goddard tion of sub-components occurred. Approxi- Space Flight Center mately 90% of the total mass was analyzed to calculate the and another 10% was accounted for but not amount of debris modeled. from the Terra The fragments were modeled as tum- spacecraft which bling spheres, cylinders, boxes or flat would survive an plates. The 1976 U.S. Standard Atmos- uncontrolled reen- phere model was used for all components. try into the Earth’s A 1-D thermal math model was used to atmosphere. The model the heat conduction in the fragments. reentry survivabil- An object is assumed to demise when the ity analysis was absorbed heat (net heat rate flux integrated performed with the over time multiplied by its surface area) is NASA Object Re- greater than or equal to the heat of ablation entry Survival of the object. The initial temperature and Analysis Tool the oxidation efficiency of all components (ORSAT), version were assumed to be 300° K and 0.5, respec- 5.8. The analysis Continued on page 4 Figure 1. Nadir view of Terra satellite in stowed configuration. broke the 4427 kg 3 The Orbital Debris Quarterly News Progress in Space Tether Sever Modeling P. KRISKO probabilities of vari- The usage of space tethers for enhanced ous tether designs. orbital decay via electrodynamic drag has in- The most recent trigued space users for many years and is un- example is the Inter- der serious investigation by a number of Agency Space De- groups throughout the world. The idea is ap- bris Coordination pealing: fitting large satellites with low cost, Committee (IADC) expendable tether/probe packages to be de- Action Item 19.1, ployed at satellite end-of-life. Through electro- ‘The risks and bene- dynamic coupling with the Earth’s magnetic fits of using electro- field, the satellite-tether system experiences an dynamic tethers in additional retarding force, resulting in more space.’ This task rapid orbital decay. This technique can greatly entails a compara- decrease the time in orbit of large, spent satel- tive test of survival lites. probabilities of elec- The implementation of a tether system trodynamic tethers carries with it a host of considerations: system- (EDTs) of different wide dynamic stability, tether and end-mass simple designs at Figure 1. Pre-launched TiPS end-masses. Spring-powered mechanism separates the end-masses at tether deployment. The masses were affec- impedances, tether deployment mechanics -- different altitudes tionately dubbed Ralph and Norton for the two principal characters in all critical to the success of such missions. Of and inclinations the classic TV series “The Honeymooners” (courtesy, Dr. Shannon chief concern at the NASA Orbital Debris during electrody- Coffey, NRL). Program Office is, of course, the care which namic orbital decay. must be taken on the part of innovators to con- Some of the results of this task are presented in distinguishes between EDT and non-EDT sider the artificial debris and natural meteoroid the International Astronautical Congress (IAC) systems simply by the time spent within alti- environment in their tether design criteria. The paper, IAC-05-B6.3.011 (see the abstract in tude regions. So an acceptable test is the long- extremely long (on the order of thousands of this issue). lived non-conducting Tether Physics and Sur- meters) and narrow (on the order of millime- The NASA results compare well to the vivability (TiPS) experiment, the only tether ters) tether designs are particularly susceptible values and trends shown in studies conducted system in orbit today. This tether connects to severing by minuscule objects traveling at by the Italian and Japanese space agencies, two similar end-masses, an upper mass of 37.7 high velocity through the environment. ASI and JAXA, respectively. The single-line kg and a lower mass of 10.8 kg (see Figure 1). The NASA Orbital Debris Program Of- tether of 1-mm diameter or less is shown to be This project, sponsored by the Naval fice is addressing the issue of helping design- unlikely to survive a de-orbit mission. A dou- Research Laboratory, was deployed on 20 ers make space debris-resistant tethers by two ble-line configuration, in which the strands June 1996 to a near-circular orbit of 1024 km x means. First, the development of a major up- remain separated by distances much greater 1019 km and 63.4° inclination and is still in- grade to the Debris Assessment Software than the strand diameters, is much more likely tact as of this writing. The tether itself is 4 km (DAS) package is nearing completion. The to survive. Also, as expected, the double-line in length and ~2 mm in diameter. However, tether survival module in DAS 2.0 provides a configurations with the larger number of loops the survival probability calculation, is compli- very simple calculation of the survival prob- (i.e., knots) have the highest survival prob- cated by the tether design. Though at first ability of a single line tether in circular orbits abilities. glance a tether diameter of ~2 mm seems ap- in low Earth orbit (LEO). Second, work is Given the maturity of the study it is ap- propriate for the survival probability calcula- underway through analysis and testing of ever- propriate to test the methodology on a real tion, this leads to a survival probability of advancing techniques to determine severing tether system. The survivability calculation Continued on page 5 Terra Satellite Continued from page 3 Joules. For the 90 tively. purposes of calcu- A total of 559 kg of mass was assessed lating risk, the 80 by the analysis to survive reentry and pro- casualty area con- 70 duce a debris casualty area of 59 m2 and a tributed by these 60 footprint length of 848 km. A plot of de- objects can be ig- mise altitude versus downrange from nored. The result- 50

breakup for all Terra objects can be seen in ing total debris 40

Figure 2. Most objects are shown to demise casualty area for (km) Altitude above 50 km in altitude. Of those that sur- objects that impact 30 vive, the objects with the lowest ballistic the ground with an 20 Propulsion Module Solar Array Drive Base Panel Shaft and bearings coefficient will comprise the heel of the impact kinetic en- 10 footprint and the objects with the highest ergy above the 15-J ballistic coefficient will comprise the toe of casualty limit is 0 0 200 400 600 800 1000 1200 1400 the footprint. A number of these objects 48.5 m2. ‹ Downrange (km) impact with a kinetic energy below an es- tablished casualty threshold limit of 15 Figure 2. Demise altitude vs. downrange for analyzed Terra objects. 4 www.orbitaldebris.jsc.nasa.gov Space Tether Continued from page 4 bearing material is Spectra-1000 polyethylene of the tether, thus improving optical tracking.2 about 1% by the end of 1999, assuming an fiber in multiple braided strands, the same The yarn invariably separates the Spectra-1000 ORDEM2000 debris flux coupled with a Grün material used for the SEDS-1 and SEDS-2 strands. Assuming that the Spectra-1000 fiber meteoroid flux model. missions. In the case of TiPS, four ropes of structure is identical to that of the SEDS-1 and However, the TiPS tether is not a mono- acrylic yarn are inserted into a twelve-strand SEDS-2 tethers, each strand is about 0.094 lithic single-line structure. The tether tension- Spectra-1000 structure to enhance the diameter mm in diameter. If these strands are consid- ered to be separated by enough distance along Effective Strand Survivability Probability Tether Representation the surface of the yarn to be modeled as twelve Diameter Percentage through 2005 distinct tethers, a survivability probability of Single-line (yarn+Spectra-1000) 2 mm 0% about 99.9% is achieved through 2005 (Table Double-line 0.563 mm 0% 1). As expected, the survival rate is shown to opposing braids separated, (6 SEDS strands together) decrease as the assumed number of separated 6 strands per opposing braid, strands decreases. overlap not considered Quadruple-line 0.281 mm 36% 1. Pardini, C., T. Hanada, P. Krisko, L. opposing braids separated, (3 SEDS strands together) 3 strands per opposing braid, Anselmo, and H. Hirayama, Are De-orbiting overlap not considered Missions Possible using Electrodynamic Teth- Sextuple-line 0.188 mm 89% ers? Task Review from the Space Debris Per- opposing braids separated, (2 SEDS strands together) spective, IAC-05-B6.3.01, 56th International 2 strands per opposing braid, Astronautical Congress, Fukuoka, Japan, 17- overlap not considered 21 October 2005. Dodecatuple-line 0.0938 mm 99.9% opposing braids separated, (all strands separated) 1 strand per opposing braid, 2. Dr. Shannon Coffey, Naval Research Labo- overlap not considered ratory, private communication, 2005. ‹

Table 1. TiPS survival for assumptions of strand separation and diameter. ABSTRACTS FROM THE NASA ORBITAL DEBRIS PROGRAM OFFICE Air Force Maui Optical and Supercomputing (AMOS) Technical Conference 5-9 September 2005, Wailea, Maui, Hawaii, USA Applying Space Weathering Models to Common Spacecraft Materials to Predict Spectral Signatures K. ABERCROMBY, M. GUYOTE, increases was noted. The increase, or particulate contamination to attach to the J. OKADA, & E. BARKER reddening as it is termed in the astronomy space object’s surface. This contamination Since May 2001, spectral observations community, appears to be material changes the reflectance properties by altering have been collected using the Spica dependent and independent of orbit or age. the refractive indices of the surface material. Spectrometer on the AMOS 1.6-m telescope. Since the reddening is not seen upon This effect was modeled by B. Hapke for These observations, when compared to returning to the Earth environment, the root asteroids and the authors have adapted it for laboratory spectra of similar material, are cause of the reddening is believed to be a human-made space objects. Particle Swarm used to determine material identification, space environment effect. One theory is theory has been used to obtain more accurate object classification, and possibly spacecraft being explored currently which could explain information about the variables. This model health. From the first set of observations, an the reddening. The theory is that oxygen will be explored and results shown in this increase in reflectance as wavelength vacates the surface leaving avenues for paper. ‹ An Optical Survey for GEO Debris in High Inclination Orbits P. SEITZER, K. ABERCROMBY, observed angular motions of the fainter de- at GEO. Very few objects have been detected J. AFRICANO, T. PARR-THUMM, bris can be explained if these are high area- that are outside the spatial range observed for M . M A T N E Y , K . J A R V I S , to-mass ratio (A/M) objects that suffer sig- bright debris on circular orbits. These obser- E. STANSBERY, & E. BARKER nificant perturbations from solar radiation vations were taken as part of the NASA/ A standard picture of the GEO debris pressure. One prediction is that such objects Michigan survey for GEO debris with MOD- population is starting to emerge from recent will have orbital inclinations much greater EST (the Michigan Orbital Debris Survey optical observations. There are two families than that expected on the basis of gravita- Telescope). of debris: bright objects on circular orbits tional perturbations alone (see Liou & This work has been supported by the with inclinations ranging up to 17 degrees, Weaver, ODQN Vol 8, page 6). We report NASA Orbital Debris Program Office at and a fainter population which appear to be the results of an optical survey designed to Johnson Space Center, Houston, Texas. ‹ on more eccentric orbits. Models suggest that detect faint objects in high inclination orbits 5 The Orbital Debris Quarterly News The LEO Environment as Determined by the LMT between 1998 and 2002 E . B A R K E R , K . J A R V I S , restricted to the low Earth orbit (LEO) phase angle, solar distance and meteor K. ABERCROMBY, T. PARR-THUMM, environment below 2100 km. The LMT dataset discrimination. The conversion of an observed J. AFRICANO, & E. STANSBERY consists of over four years of observations brightness to a physical size requires the The National Aeronautics and Space totaling almost 1100 hours with 805 of those assumption of an albedo for the object or a Administration (NASA) operated the 3.0 m hours covering the LEO environment. model which relates the radar cross section Liquid Mirror Telescope (LMT) at Cloudcroft, Observational and reduction techniques have (RCS) to a characteristic length for the object. New Mexico between October 1998 and changed and improved over the period of the These size conversions will be discussed in December 2002. The purpose of this LMT performance and analysis. The observed terms of the entire database. The complete presentation is to summarize datasets of magnitudes for the LMT database have not LEO dataset for the LMT will be presented in detected correlated (CTs) and uncorrelated been corrected for solar phase angle or solar terms of distributions such as inclination, size, (UCTs) targets which have been presented in a distance variations. Subsequent analysis has magnitude, and flux. Seasonal and/or trend series of yearly reports. Although the LMT in indicated that the detections at altitudes below variations of the observed fluxes for a given its zenith staring mode could monitor the 600 km are contaminated by meteor detections. size range will be compared to the concurrent orbital debris environment at altitudes up to A summary dataset will be presented that has radar fluxes and those fluxes predicted by the ~40,000 km, this summary analysis will be uniform data corrections for observed range, ORDEM2000 model. ‹ 56th International Astronautical Congress 17-21 October 2005, Fukuoka, Japan The Historical Effectiveness of Space Debris Mitigation Measures N. JOHNSON adopted a wide range of debris mitigation the disposal of satellites. Mitigation measures Nearly a quarter century has passed since practices which have arguably reduced the rate have been classified according to their near- a new emphasis on space debris mitigation of growth of the debris population in Earth term and far-term consequences and to the began, following two, nearly simultaneous orbit. A study has been undertaken to quantify degree of their implementation by the seminal events: the publication of “Space the likely historical effects of these debris international aerospace community. The Debris: An AIAA Position Paper” and the mitigation measures on the current satellite history of space debris mitigation measure realization that numerous, intense Delta population based upon vehicle-specific launch application can be used in conjunction with second stage fragmentations had been induced rates. The mitigation measures addressed in long-term satellite evolutionary models to by residual propellants. Since that time the the study include those associated with provide a more realistic expectation of the major space-faring nations of the world have mission-related debris, satellite breakups, and future environment. ‹ Are De-Orbiting Missions Possible Using Electrodynamic Tethers? Task Review from the Space Debris Perspective C. PARDINI, T. HANADA, P. KRISKO, space debris perspective. In particular, the survivability concern is fully justified for a L. ANSELMO, & H. HIRAYAMA because of their small diameter, tethers of single line tether and no de-orbit mission, Over 9000 satellites and other trackable normal design may have a high probability of from the altitudes and inclinations considered, objects are currently in orbit around the Earth, being severed by impacts with relatively small is possible if the tether diameter is smaller along with many smaller particles. As the low meteoroids and orbital debris. This paper than a few millimetres. The survival probabil- Earth orbit is not a limitless resource, some compares the results obtained at ISTI/CNR, ity is shown to grow for a double line sort of debris mitigation measures are needed the Kyushu University and NASA JSC configuration with a sufficiently high number to solve the problem of unusable satellites and concerning the vulnerability to debris impacts of knots and loops. The results are strongly spent upper stages. De-orbiting devices based on a specific conducting tether able to de-orbit dependent on the environment model adopted on the use of conducting tethers have been spacecraft in inclinations up to 75° and initial and the MASTER-2001 orbital debris and recently proposed as innovative solutions to altitude less than 1400 km. A double line meteoroids fluxes result in survival probabili- mitigate the growth of orbital debris. tether design has been analysed, in addition to ties appreciably higher than those of OR- However, electrodynamic tethers introduce the single wire solution, in order to reduce the DEM2000 coupled with the Grün meteoroids unusual problems when viewed from the tether vulnerability. The results confirm that model. ‹ A Statistical Analysis on the Future Debris Environment J.-C. LIOU future debris populations is to take the average orbital debris evolutionary model LEGEND. Modeling the future orbital debris of multiple Monte Carlo runs. The number of The input parameters are identical for all the environment is a difficult task. In addition to available runs is typically between 10 and 30, simulations. We examine the projected debris making reasonable assumptions on key depending on the speed of the simulation populations in terms of the mean, median, parameters such as future launch traffic and program and computer. However, the "mean standard deviation, and uncertainty-in-the- solar activity, one needs to rely on a Monte growth" from a limited number of Monte mean. The number of runs needed to derive a Carlo process to evaluate future on-orbit Carlo simulations may not reveal the complete stable mean population is discussed. We also explosions and collisions. Even with the same picture of what the future environment might analyze the distribution of the debris popula- input parameters, the outcome of the projected be. tions at the end of the 100-year projection. debris populations could vary significantly In this paper, we analyze a total of 200 Good scenarios are compared with bad from one Monte Carlo run to the next. A Monte Carlo simulations of the future debris scenarios. Triggers for the worst case scenarios common approach to assess the growth of environment using the NASA long-term are identified and discussed. ‹ 6 www.orbitaldebris.jsc.nasa.gov A Minimalist Empirical Orbital Debris/Meteoroid Hazard Model for the Space Shuttle M. MATNEY & E. CHRISTIANSEN to assess the results at a “back-of-the- Shuttle surfaces (radiators, windows, etc.) is Impact hazards due to orbital debris and envelope” scale. This technique is necessary used to quantify the probability of critical meteoroids for the Space Shuttle and other for those outside a narrow technical specialty damage in a simple calculation of the relative spacecraft have been studied for many years. to understand and critically examine the probability that the same impact could have To date, many sophisticated environment assumptions and computations of the occurred on certain other areas of the Space models (such as NASA’s ORDEM2000) and models. In an effort to address this chal- Shuttle where the impact would have caused collision hazard models (such as NASA’s lenge, we present in this paper an empirical critical damage. These empirical results will BUMPER) have been developed to accu- model of the Space Shuttle orbital debris/ then be compared with the results of the rately assess the overall risk to orbiting meteoroid hazard based on empirical data more sophisticated models. ‹ vehicles. However, as models get progres- and a minimum of model assumptions. Data sively more complex, it is sometimes useful from non-critical damage on returned Space The Object Reentry Survival Analysis Tool (ORSAT) – Version 6.0 and its Application to Spacecraft Entry J. DOBARCO-OTERO, R. SMITH, the NSS guideline of 1:10,000, the higher- spheres, cylinders, cones, and flat plates; drag K. BLEDSOE, R. DELAUNE, fidelity Object Reentry Analysis Survival coefficients for cones; and general program W. ROCHELLE, & N. JOHNSON Tool (ORSAT) might be required. Various improvements. Additional improvements NASA Safety Standard (NSS) 1740.14 versions of this code have been used in the also include a Graphical User Interface requires that each NASA reentering past 10 years to perform over 20 different (GUI), gas cap radiation at high entry spacecraft and launch vehicle upper stage be spacecraft reentry analyses. The object of velocities, recession for non-metallic assessed as a human casualty risk to the this paper is to discuss the new features of the insulation materials, structural failure of solar world’s population upon impact of all latest version – ORSAT 6.0. These features array hinges, tank bursting, Unix/Linux surviving debris to the Earth. As a first include replacement of the trajectory model plotting scripts, an expanded materials approach, the risk is usually evaluated with and improvement of the gravitational model; property database, and trajectory mapping on the slightly conservative NASA Debris incorporation of the GRAM atmosphere and a world map. Sample results are presented Assessment Software (DAS). However, if a user-defined atmosphere model; 2-D for reentry of selected spacecraft using these the DAS assessment of the risk does not meet heating rate and temperature variation around updated features in ORSAT. ‹ Orbital Parameters for Objects Observed by the Michigan Orbital DEbris Survey Telescope (MODEST) K. ABERCROMBY, T. PARR-THUMM, uncorrelated targets (unique per night). This magnitude peak is near 11 and the uncorre- P. SEITZER, K. JARVIS, E. BARKER, paper will discuss the orbital parameters lated target absolute magnitude peak is near M. MATNEY & E. STANSBERY determined for correlated and uncorrelated 16-17. The falloff in sensitivity of the An optical survey for orbital debris at objects based on a circular orbit assumption. telescope keeps the uncorrelated absolute geosynchronous orbit has been conducted The average inclination error for all corre- magnitude peak from being known com- with the University of Michigan's 0.6/0.9-m lated targets is 0.02° with a standard devia- pletely. Depending on the pointing of the Schmidt telescope at Cerro Tololo Inter- tion of 0.78. The average error for right telescope, the possible orbit planes in which American Observatory in Chile. The project accession in ascending node (RAAN) is an object can be determined. The coverage termed MODEST (Michigan Orbital DEbris 0.35° but with a standard deviation of 60. is nearing completion but is still missing one Survey Telescope) has been collecting data However, the average error for RAAN for segment starting at 5° inclination through since 2002. Included in this paper are 66 objects with inclinations greater than one 30° within the RAAN ranges of 250 – 300°. days of observation from calendar years degree increases slightly to 1.6° while the A description of the orbits which were 2002, 2003, 2004, 2005, which yield 100 standard deviation decreases to 17.5. In calculated within the possible orbital planes different field locations. Combining all three addition to the orbital parameters, calcula- will be addressed. ‹ years of data, MODEST observed 1014 tions of visual and absolute magnitude have correlated targets (unique per night) and 401 been made. The correlated targets absolute A Statistical Size Estimation Model for Haystack and HAX Radar Detections Y.-L. XU, C. STOKELY, M. MATNEY, resonant region of radiative scattering. The an object’s RCS with shape, composition, E. STANSBERY, & G. BOHANNON basis of the size estimation model (SEM) structure, and orientation for a given size. A The Long Range Imaging Radar NASA developed in 1991 was a static RCS given RCS does not correspond to a unique (LRIR), also known as Haystack, and the measurement experiment using a set of size. The statistical inference of the size Haystack Auxiliary (HAX) radar have been hypervelocity impact fragments. As one of distribution is based on the posterior distri- observing the orbital debris environment for the end products of the experiment, SEM is a butions obtained from the Bayes’ rule. One more than a decade. One of the key radar simple model for one-to-one RCS-to-size benefit associated with this iterative statisti- measurements is the radar cross section conversion based on the orientation- and cal approach is that the uncertainty analysis (RCS) of each object detected. The conver- shape-averaged RCS of the hypervelocity becomes easy and straightforward. This new sion from RCS to target size is a complicated impact fragments as a function of size. approach has been applied to recent Hay- inverse problem especially when the size of In this paper, we propose a Bayesian stack and HAX data. Results of the Bayesian the object is comparable to the wavelength approach to improve the original NASA inference and comparisons with the original of incident radiation, i.e., in the so-called SEM. It takes into account the distribution of SEM are included in the paper. ‹ 7 The Orbital Debris Quarterly News Dust in Planetary Systems 26-30 September 2005, Kauai, Hawaii, USA Adventures in Gravitational Focusing M. MATNEY meteoroid sources away from the planet in examples on how spacecraft experiments The forces of gravity near a planet can interplanetary space. However, this effect can be designed to use a planet's gravity as have a profound effect on the flux, speed, can also be used creatively to extend and a giant "lens" to aid in the detection and and directionality of meteoroids in space. enhance the capability of orbiting sensors. identification of meteoroid sources. This gravitational focusing effect In this paper, I review the Liouville selectively intensifies low-velocity method for computing gravitational 1. Matney, M.J. Dust in the Solar System meteoroid fluxes relative to high-velocity focusing originally outlined in Matney, and Other Planetary Systems, COSPAR ones. This effect can lead to biases when 2002 [1]. Then, I present examples of how Colloquia Series Vol. 15, 2002, p. 359- using fluxes measured within a planet's planetary gravity affects meteoroid fluxes 362.‹ gravitational field to understand the on spacecraft. I conclude with ideas and Characterizing the Near-Earth Cosmic Dust and Orbital Debris Environment with LAD-C J.-C. LIOU, F. GIOVANE, R. CORSARO, impacts represent a threat to space identification. P. TSOU, & E. STANSBERY instruments, vehicles, and extravehicular What to expect: The expected Introduction: A 10 m2 aerogel and activities. On average, two Space Shuttle number of cosmic dust and orbital debris acoustic sensor system is being devel- windows are replaced per mission due to impacts on LAD-C depends on the oped by the US Naval Research Labora- damage caused by meteoroid and orbital location of the system on ISS and the tory (NRL) with main collaboration from debris impacts. Of particular signifi- orientation of the detection surface. Both NASA Jet Propulsion Laboratory and the cance are particles about 50 μm and the location and orientation are limited NASA Orbital Debris Program Office at larger. Particles smaller than 50 μm are by engineering constraints and the Johnson Space Center. This Large Area generally too small to be of concern to requirement to avoid significant ISS Debris Collector (LAD-C) is tentatively satellite operations. To have reliable waste contamination. To maximize the scheduled to be deployed by the US impact risk assessments for critical science return for cosmic dust and Department of Defense (DoD) Space space assets, a well-defined cosmic dust/ orbital debris, careful planning is Test Program (STP) on the International orbital debris environment is needed. needed. Preliminary analysis indicates Space Station (ISS) in 2007. The system The near-Earth cosmic dust flux that a starboard/port-facing orientation will be retrieved after one year. In does not vary significantly over time. On will yield the most debris impacts while addition to cosmic dust and orbital the other hand, the orbital debris popula- maintaining a high-level of cosmic dust debris sample return, the acoustic tions in the 50 μm to 1 mm size regime impacts. In addition, a significant sensors will measure important impact are highly dynamic both in time and in portion of orbital debris impacts on a characteristics for potential orbit deter- altitude. However, there is a lack of starboard/port-facing surface will have mination of the collected samples. The well-designed, large surface area in situ impact speeds less than 7 km/sec, where LAD-C science return will benefit measurements to better characterize the the impact characteristics are better orbital debris, cosmic dust, and satellite cosmic dust environment and to monitor understood and the tracks embedded in safety communities. This paper outlines the fast-changing small orbital debris aerogel are better preserved. the need for a large-area cosmic dust and populations since the return of the Long orbital debris in situ experiment such as Duration Exposure Facility (LDEF) in 1. Grün et al. (1985) Icarus, 62, 244- LAD-C, and the expected dust/debris 1990. There is a need for an updated 272. impacts on LAD-C during the mission. mission. 2. Love S. G. and Brownlee D.E. (1993) Background: Cosmic dust parti- Analyzing the chemical composition Science, 262, 550-553. cles, or micrometeoroids, are known to of the collected cosmic dust can provide exist throughout the Solar System. The clues to the origin and formation of the 3. Technical Report on Space Debris main sources of micrometer-to- Solar System. The information also leads (1999), Scientific and Technical Sub- centimeter sized dust in the inner Solar to a better understanding of the on-going committee of the United Nations, United System are asteroids and comets (both physical processes (collisions, etc.) that Nations Publication No. E.99.I.17.

long-period and short-period). The their parents are going through. Many 4. Analysis of Interplanetary Dust Earth's accretion rate of cosmic dust is cosmic dust particles have been col- (1994), AIP Conference Proceedings 310 estimated to be about 15,000 to 40,000 lected from the stratosphere and ana- (Eds. Zolensky et al). tons per year1, 2. In addition to cosmic lyzed for their compositions4. However, dust, man-made orbital debris, from a reliable dynamical link has not been 5. Corsaro, R. et al. (2004) NASA micrometer-sized solid rocket motor established for any collected sample. Orbital Debris Quarterly News, Vol 8, exhaust and satellite breakup fragments The combined LAD-C acoustic sensors5 Issue 3, 6-7. 6 to meter-sized retired spacecraft and and aerogel collectors are designed to 6. Tsou, P. et al., (2003) JGR, 108, rocket bodies, also occupy the near- measure impact parameters (impact time, 10.1029. ‹ Earth space from about 100 km altitude location, speed, direction) for large up to the geosynchronous orbit region3. particles. With the information, the Justification: It is a well-known orbits of some of the collected samples fact that meteoroid and orbital debris can be determined for possible source 8 www.orbitaldebris.jsc.nasa.gov INTERNATIONAL SPACE MISSIONS ORBITAL BOX SCORE (as of 05 OCT 2005, as cataloged by July—September 2005 US SPACE SURVEILLANCE NETWORK)

Earth Rocket Other Country/ International Country/ Perigee Apogee Inclination Orbital Payloads Bodies Total Payloads Cataloged Designator Organization (KM) (KM) (DEG) Rocket Organization Debris & Debris Bodies CHINA 51 312 363 2005-024A SJ-7 CHINA 555 573 97.6 1 5 CIS 1358 2692 4050 ESA 34 32 66 2005-025A ASTRO E2 JAPAN 562 573 31.4 1 0 FRANCE 42 295 337 INDIA 30 113 143 2005-026A STS 114 USA 313 350 51.6 0 0 JAPAN 88 57 145 US 1010 2959 3969 2005-027A FSW-3 4 CHINA 161 331 63.0 1 7 OTHER 339 20 359

2005-028A IPSTAR 1 THAILAND 35782 35795 0.0 1 0 TOTAL 2952 6480 9432 2005-029A MRO USA INTERPLANETARY 0 0 Technical Editor 2005-030A GALAXY 14 USA 35782 35791 0.0 1 0 J.-C. Liou

2005-031A OICETS JAPAN 596 613 97.8 1 7 Managing Editor Sara Portman 2005-031B INDEX JAPAN 601 650 97.8 Correspondence concerning 2005-032A MONITOR-E RUSSIA 522 545 97.6 1 0 the ODQN can be sent to: Sara Portman 2005-033A FSW-3 5 CHINA 191 259 63.0 1 2 NASA Johnson Space Center 2005-034A COSMOS 2415 RUSSIA 202 270 64.9 1 0 Orbital Debris Program Office

2005-035A PROGRESS-M 54 RUSSIA 347 350 51.6 1 0 Mail Code JE104 Houston, Texas 77058 2005-036A ANIK F1-R CANADA 35769 35800 0.1 1 1 [email protected] 2005-037A STP-R1 (USA 185) USA 294 319 96.3 1 1 2005-038A NAVSTAR 57 (USA 183) USA 20006 20187 55 2 0 UPCOMING MEETING REPORT MEETINGS Air Force Maui Optical and Supercomputing (AMOS) Technical Conference 4-11 June 2006: The 25th International Space 5-9 September 2005, Wailea, Maui, Hawaii, USA Technology and Science (ISTS) Conference, Kanazawa, Japan. The 2005 Air Force Maui Optical tion, retrograde orbits. Edwin Barker The conference will include technical sessions and Supercomputing (AMOS) technical from NASA gave a talk on the Liquid on space debris and a panel discussion session on conference occurred 5-9 September 2005 Mirror Telescope (LMT) observations international space law of space debris. Additional in Wailea, Maui. The general topics from 1998-2002 and the low Earth orbit information on the Conference is available at http:// discussed at the conference were open (LEO) environment determined from the www.ists.or.jp. sessions on: imaging, non-resolved ob- observations. The LMT dataset has ap- 16-23 July 2006: The 36th Scientific Assembly ject characterization, orbital debris, met- proximately 1100 hours of data. Patrick COSPAR 2006, Beijing, China. rics, instrumentation, astronomy, wide Seitzer presented findings on the Univer- Three Space Debris Sessions are planned for field survey systems, space weather, sity of Michigan/JSC NASA MODEST the Assembly. They will address the following lasers, high performance super comput- project which is an optical survey of issues (1) advanced ground-based radar and ing, adaptive optics, and a poster session geosynchronous orbit (GEO) space. optical, and space-based in-situ measurements, (2) with various topics. Below is a discus- This talk was aimed specifically at find- population and environment modeling, (3) debris sion of the orbital debris session. ing objects in high inclination orbits. mitigation measures, (4) re-entry tracking and Timothy Payne delivered a paper Thomas Schildknect discussed a new survival analysis, and (5) hypervelocity impact regarding a confirmation of an uninten- population of objects found by the ESA testing and shielding design. The meeting will also tional on-orbit collision which occurred telescope at Tenerife. These objects discuss new developments toward national and on 17 January 2005 between a piece of have variable eccentricities as a by- international standards and guidelines. More debris from a Chinese rocket body and product of their high area-to-mass ratio. information for the conference can be found at an old U.S. rocket body. The collision Follow-up measurements have been http://meetings.copernicus.org/cospar2006/. occurred between objects in high inclina- conducted. ‹ 9 The Orbital Debris Quarterly News ebris sizes. Debris as small as a few tenths of a millimeter a millimeter of tenths few a as small as Debris sizes. ebris ed to assess the full spectrum of orbital d to ed ors and spacecraft surface inspections are requir inspections are ors and spacecraft surface can cause replacement of a Space Shuttle window or penetrate an astronaut's suit during a spacewalk. a spacewalk. during suit astronaut's an or penetrate window Shuttle a Space of replacement cause can A wide variety of ground-based sens ground-based A wide variety of

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