Session 8 - Space Systems Development and Operations: Dealing with Space Weather and Space Climate Effects

Eamonn Daly (European Space Agency), Dave Pitchford (SES), Hugh Evans (ESA)
Wednesd 16/11, 10:00-13:00
Mercator

Spacecraft have to survive in hostile environments that can induce a variety of radiation and plasma effects. Those effects will be the focus of this session. They will be discussed in the context of both space weather (transient phenomena) and “space climate”, which we define as quasi-permanent or slowly evolving environmental features such as cosmic rays, the proton radiation belt, the geomagnetic main field, etc.. Although space weather effects are important, there is an important complementary group of effects that are attributable to space climate. In the development of space systems, including elements such as manned and unmanned spacecraft, launchers, transfer vehicles and constellations, considerable engineering effort is devoted to ensuring the correct functioning in the presence of the space environment. The engineering effort includes processes such as radiation hardness assurance and electromagnetic compatibility analysis, which include evaluations of environmental interactions(*). The session will compare space weather effects with other radiation and plasma hazards and discuss in detail the means which are deployed to address them. The objective is to put space weather phenomena into context when evaluated alongside “space climate” effects. Presentations and discussions will include end-to-end analyses and so expose the space weather community to end-user concerns, the use of standards, equipment testing, system design, engineering margins, return-on-experience and other practical issues.


(*) Issues evaluated for radiation hardness include total ionizing and non-ionizing doses, and single event effect (SEE) rates. Ionizing dose is usually a concern for mission lifetime and so long-term average models of the radiation belt environment are used, augmented by statistical models of solar particle event (SPE) risks. In most near-earth missions, the dose from SPEs is relatively small compared to radiation belt doses. For single event effects the principal environments of concern are galactic cosmic rays and the inner, proton, radiation belt. The solar particle ion environment is also considered, since high rates during SPEs may disrupt systems more severely, for example in star trackers. Most SPEs have energy spectra and compositions that do not pose much of a problem. More troublesome are the problems from energetic protons in the inner radiation belt that induce SEEs through nuclear interactions. This is a relatively stable environment so can be thought of as climatological, responding to slow changes in the geomagnetic main field and the changes in the cosmic ray albedo neutron source.

Poster Viewing
Wednesday November 16, 11:00 - 11:00, Poster Area

Talks
Wednesday November 16, 11:00 - 13:00, Mercator

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Talks : Time schedule

Wednesday November 16, 11:00 - 13:00, Mercator

11:00	Space Radiation and Plasma Effects on Spacecraft: Coping with Weather and Climate	Daly, E et al.	Oral
	E. Daly [1], H. Evans[2], P. Jiggers[3], A. Hilgers[1]
	[1]European Space Agency, [2]ESA/ESTEC (Rhea), [3]European Space Research And Technology Centre
	We outline the steps which are taken during the design phases of space mission development at ESA to quantify hazardous space environment conditions, and to support the mitigation against them. In doing this, account must be taken of long-term degradation of equipment, of the rates or durations of interference with equipment functioning, and the possibility of sudden interference from “enhanced” conditions. Practically, this means establishing an environment specification early in a project’s development, based on the orbit or location. The specification is based on standard models that represent: i. long-term averages of radiation belt proton and electron fluxes; ii. short term enhancements of electron fluxes; iii. statistics of deviations from the long-term average (as described in most recent AE-9 models); iv. risk assessment of solar particle event proton/ion fluences and peak fluxes; v. worst case plasma charging environment; vi. low energy ion long term fluxes for evaluation of surface degradation; vii. solar cycle modulates GCR fluxes; viii. geomagnetic modulation of (iv) and (vii) if required by the orbit. In addition, some derived quantities are provided to enable early assessment of radiation hardness requirements and preliminary radiation shielding requirements. These include ionizing and non-ionizing dose. During further project development, detailed evaluation of radiation and plasma effects are made, supported by radiation and plasma/EMC testing. The evaluations make use of tools for evaluation of effects and mitigation measures. Mitigation can be with radiation shielding, or, in the case of electrostatic charging, appropriate material selection, for example. At the end of the development the objective is to have a spacecraft that is “hardened” against space environmental problems and to have a clear understanding of environment related risks. Once launched, it is expected that the engineering measures taken will have hardened the mission against problematic effects- for example that ESDs that may occur do not result in propagating EM disturbances; that electronic systems experiencing single event effects are designed so that they are correctable, etc. The hardening strategy includes application of appropriate “design margins” and it may be that systems are being systematically over-designed, with a cost penalty. Efforts are being made to reduce overdesign. Experience shows that in spite of the hardening, spacecraft often exhibit unexpected behaviour that may require operational measures to be taken. Although some effects may be due to space weather events, they are often due to the more static elements of the space environment such as galactic cosmic rays or radiation belt protons.
11:17	Space Radiation Environment and Situational Awareness (SSREA) Monitors	Blake, B et al.	Oral
	J. Bernie Blake
	Aerospace Corporation
	It was long recognized that SSREA monitors would be highly desirable for all space missions. The key issue is that, to be considered for general engineering use, such monitors had to require minimal spacecraft resources, be of modest cost yet provide reliable data. Historically, SSREA measurements have been made by sophisticated, complex, and costly scientific instruments. While such instruments have yielded excellent data, the spacecraft missions carrying them have been few in number because of the size and cost constraints that are imposed by the project’s resources. To address this problem, Aerospace developed a new class of targeted miniature SSREA sensors.  Development of SSREA monitors began with the advent of a dosimeter capable of measuring the radiation dose at many positions within an orbiting spacecraft, not just at the surface, and thus the external environment. The development was successful and such devices have flown aboard several spacecraft including the NASA Lunar Reconnaissance Orbiter and Van Allen Probes, the two Aerospace Aerocube 6 cubesats as well as other, yet unpublicized missions. This dosimeter weighs about 20 grams which is orders of magnitude less than conventional scientific instruments, and it was made commercially available from Teledyne Micro-electronics. Since then development of SSREA monitors at Aerospace has continued. One focus has been to substantially lower the energy thresholds.  The first dosimeter had an intrinsic electron energy threshold of ~ 500 keV and a proton threshold of ~ 10 MeV which made it useful for monitoring total dose and deep dielectric charging. The Aerocube 6 mission carried dosimeters with reduced thresholds of 35 keV for electrons and 500 keV for protons in order to obtain measurements partly responsible for surface charging. Additional monitors that are also spaceflight ready have included surface dose monitors for trending damage of surface coatings with energy thresholds even below 1 keV, surface charging monitors for monitoring the charging behavior of material samples, and an electro-static discharge recorder for detecting spacecraft ESD inflight.  These new sensors are also miniature micro-electronic hybrid devices suitable for CubeSats and larger spacecraft alike.
11:34	Space Environment Effects on ESA Science Missions	Prod'homme, T et al.	Oral
	T. Prod'homme and L. Duvet
	European Space Agency
	Science missions are often very sensitive to the space environment since the payloads are usually built to perform with high performance in difficult conditions. Several past missions have exhibited effects due to the environment and in preparing future missions much care is taken to analyze the potential effects of radiation or plasmas on the mission. Some past mission effects will be discussed. Future planned ESA science missions such PLATO, Euclid, CHEOPS, SMILE and ATHENA, along with missions under evaluation and themes related to the ESA calls for ideas (“M4, “M5”) will be outlined and the challenges and mitigation means with respect to the space environment highlighted. Further in the future, a “large class” gravitational wave observatory will also have to contend with particle effects.
11:51	Space radiation crew protection and operations for exploration missions	Gaza, R et al.	Oral
	Ramona Gaza[1], Kerry Lee[2], Dan Fry[2], Janet Barzilla[1], Steve Johnson[1], Nic Stoffle[1], John Keller[3], Robin Elgart[4], Edward J. Semones[2]
	[1]Lockheed Martin/NASA Johnson Space Center, TX 77258-8487, USA; [2]NASA Johnson Space Center, Houston, TX 77058, USA; [3]KBRwyle, Houston TX 77058, USA; [4]University of Houston, Houston TX 77004, USA
	Monitoring space radiation is of vital importance for risk reduction strategies in human space exploration. Crew protection from severe space weather events during exploration missions outside Low-Earth Orbit (LEO) is drastically different than for the International Space Station (ISS) where the crew can benefit from the inherent protection provided by the Earth’s magnetic field. Factors such as vehicle shielding design, real-time radiation monitoring capabilities, space weather forecasting tools and mission planning are crucial for a successful human exploration radiation protection program outside the Earth’s magnetic field. The specifics of different exploration missions need to be considered and appropriate space weather monitoring assets need to be identified [1, 2]. Below is an example of the NASA Orion Multipurpose Crew Vehicle (MPCV) radiation measurements as a function of altitude during the Exploration Flight Test 1 (EFT-1) on December 5, 2014. The EFT-1 trajectory involved one low and one high altitude orbit with an apogee of ~ 6000 km. As a result of this particular flight profile, the EFT-1 provided a unique opportunity for radiation measurements through intense regions of trapped proton and electron belts. Even though there were no significant space weather events during the 4.5 hour EFT-1 flight, the average dose rate measured reached 3.97 mGy/h, about ~300-500 times higher than average ISS dose rate [3, 4]. Mars radiation measurements from the Mars Science Laboratory (MSL) Curiosity Rover in 2012, provided by the MSL Radiation Assessment Detector (RAD) instrument during the cruise phase, showed the dose equivalent contribution from several solar energetic particle (SEP) events to be between 1.2 mSv and 19.5 mSv [5]. The radiation environment that crews on long duration exploration missions can be exposed to will be very different than that of Low Earth Orbit (LEO). As a result, to support human exploration to Mars and beyond, new concepts of operations need to be developed together with space weather predictive tools (i.e., All-clear 24h window forecasting tool currently tested by NASA) that will be able to go beyond the current nowcasting tools currently used to support LEO ISS missions. This presentation will include measurements made for Exo-LEO missions, models and tools used for radiation exposure predictions, and space weather forecasting needs for long duration exploration missions. References [1] Fry, D., Lee, K., Zapp, N., Barzilla, J., Dunegan, A., Johnson, S., Stoffle, N., 2011. “Space weather status for Exploration Radiation Protection”. Heavy Ion in Therapy and Space Radiation Symposium 2011, Chiba, Japan. [2] Falconer, D., Barghouty, N., Khazanov, I., Moore, R., 2016. “An All-Clear Space Weather Forecasting System Based on Magnetogram in Near Real Time”. NASA publication MSCF-E-DAA-TN29431. [3] Gaza, R., Kroupa, M., Rios, R., Stoffle, N., Semones, E., 2016. “Comparison of novel active semiconductor pixel detector with passive radiation detectors during the NASA Orion exploration flight test 1 (EFT-1)”. 18th International Solid State Dosimetry Conference, Munich, Germany. [4] Bahadori, A., Semones, E., Gaza, R., Kroupa, M., Rios, R., Stoffle, N., Campbell-Ricketts, T., Pinsky, L., Turecek, D., 2015. “Battery–operated Independent radiation detector data report from Exploration Flight Test 1”. NASA/TP-2015-218575. [5] Hassler, D., Zeitlin, C., Wimmer-Schweingruber, R., Ehresmann, R., Scot Rafkin, S., Eigenbrode, J., Brinza, D., Gerald Weigle, G., Böttcher, S., Böhm, E., Burmeister, S., Guo, J., Köhler, J., Martin, C., Reitz, G., Cucinotta, F., Kim, M., Grinspoon, D., Bullock, M., Posner, A., Gómez-Elvira, J., Vasavada, A., Grotzinger, J., MSL Science Team, 2014. “Mars’s Surface Radiation Environment Measured with the Mars Science Laboratory’s Curiosity Rover”. Science 24, Vol.343, Issue 6169.
12:08	Single Event Effects Considerations for Spacecraft Design	Likar, J et al.	Oral
	Justin Likar[1], Dave Pitchford[2]
	[1]UTC Aerospace Systems; [2]SES
	(PLACEHOLDER)This talk will discuss the increasing importance of Single Event Effects in the context of space systems using highly complex integrated circuits.
12:25	Spacecraft charging related to low energy plasma environment at GEO and MEO	Mateo-velez, J et al.	Oral
	Jean-Charles Matéo-Vélez[1], Angélica Sicard Piet[1], Thierry Paulmier[1], Denis Payan[2], Natalia Ganushkina[3]
	[1]ONERA The French Aerospace Lab; [2]CNES French Space Agency; [3]FMI Finish Meteorological Institute
	Spacecraft surface charging is responsible for the occurrence of anomalies related to the sudden release of energy through electrostatic discharges (ESD). Some equipments are sensitive to the associated electromagnetic transients. Severe failures occurred in the past due to ESDs triggering at sensitive locations, especially power lines and solar arrays. Surface charging originates from low energy plasma sudden injection during space weather events. Spacecraft design engineers relies on flight measurements, models and ground testing to assess the behavior of material in space. In this work, we analyze the worst environment at GEO deduced from 15 years of data on LANL spacecraft. Largest low energy fluxes have been observed during well known events (Halloween event, Bastille day). We have applied a necessary correction on LANL data based on appropriate estimation of the spacecraft potential and on Liouville theorem. We use the ion peak line instead of routinely produced potential based on electron and proton distribution function moments. It is shown also that longest periods at large negative potential (above - 5 kV) all occurred during eclipse which involves a complex interaction between the spacecraft, the plasma environment and material at Sun or at shade. Special care will be given to cross compare the environment met by and the electrostatic behavior of LANL spacecraft flying at the time of worst case events. We expect to present also the numerical simulation of spacecraft charging with SPIS, the Spacecraft Plasma Interaction Software, under these GEO conditions. MEO orbit is poorly described with respect to GEO in terms of low energy plasma. The THEMIS and RBSP data are under analysis and should be presented in a companion paper. In this talk, we present briefly a preliminary numerical investigations performed with IMPTAM used to fit LANL data at GEO during worst cases and to extrapolate them at MEO. The final part of this talk concerns the modification of the ONERA test facility called SIRENE. It is equipped with 10 keV to 400 keV electron guns and currently fits the kp greater than 5 GEO electron environment. It is frequently used to understand dielectric covering behavior under space like conditions, including radiation induced conductivity, ageing, effect of temperature, etc. In this study we updated the test setup in order to adapt to the worst-case environments. This facility will be applicable soon to different conditions, including GEO and MEO. The research leading to these results was partly funded by CNES French Space Agency and by the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement No 606716 SPACESTORM and by the European Union’s Horizon 2020 research.
12:42	Atomic Oxygen modelling and its impact on LEO spacecrafts design	Zitouni, B et al.	Oral
	Bayrem Zitouni
	OHB Systems
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Posters

Wednesday November 16, 11:00 - 11:00, Poster Area

1	New capabilities of SPENVIS Next Generation and their benefits for spacecraft designers and operators	Messios, N et al.	p-Poster
	Neophytos Messios[1], Stijn Calders[1], Erwin De Donder[1], Michel Kruglanski[1], Edith Botek[1], Fabiana Da Pieve[1], Daniel Heynderickx[2], Benjamin Bode[3], Pablo Beltrami[3], Ignacio Grande[4], Eugenio Rodríguez-Moreno[4], Noelia Sánchez Ortiz[4], Ngoc-Diep Ho[5], Hugh Evans[6], Eamonn Daly[6], David Rodgers[6]
	[1]BIRA-IASB; [2]DHConsultancy BVBA; [3]etamax space GmbH; [4]Deimos Space; [5]Space Application Services NV/SA; [6]ESA/ESTEC
	ESA's Space Environment Information System (SPENVIS) is an on-line resource for evaluating the space environment and its effects on spacecraft components and astronauts. SPENVIS has a long and acclaimed history with a mature user community from all over the globe that is using the system for various purposes including mission analysis and planning, education and scientific research. Recently, a novel SPENVIS system with a web-based service-oriented distributed framework supporting plug-in of models has been developed under the ESA/GSTP-5 programme. The SPENVIS Next Generation offers a user-friendly interface for rapid analysis but also a machine-to-machine interface for interoperability with other software tools. Like its predecessor, SPENVIS Next Generation provides access to a large number of space environment models and related analysis tools, allowing the users to combine and chain results between different models. In addition, the new system delivers an easy way to perform simulations that are fully compliant with the European Cooperation for Space Standardization (ECSS) recommendations. The purpose of this talk is to introduce these new capabilities of SPENVIS Next Generation and demonstrate how spacecraft designers and operator can benefit from them.
2	The electrostatic cleanliness programme to cope with spacecraft charging on Solar Orbiter mission	Hilgers, A et al.	p-Poster
	A. Hilgers[1], F. Cipriani[2], S. Guillemant[1], P. Laget[1], S. Strandmoe[1], P. Marliani[1]
	[1]ESA; [2]RHEA/ESA
	Spacecraft interact with their plasma environment leading to electrostatic perturbation that may affect the performance of plasma instruments. The case of solar orbiter mission is extreme in the sense that requirements set by the instruments are very constraining and the hot plasma environment of the inner heliosphere make them very challenging. These challenges are being addressed thanks to a rigorous electrostatic cleanliness programme. Details of the programme and the current status will be presented.
3	Solar particle events and evaluation of their effects during spacecraft design	Jiggens, P et al.	p-Poster
	Piers Jiggens
	European Space Agency
	Solar energetic particle events are one of the important radiation features of a space mission to analyse as part of the design phase. During early project phases, the environment specification is created, in accordance with standards which describe the statistical and empirical models to be used in the specification. The specification deals with long-term accumulated fluences and doses from events, accumulated typically over several years. However, it also has to anticipated temporal effects on the system, such as star tracker blinding and payload interference and so often a specification describes the statistics of events in terms of the time an event spends above a threshold for a specified energy (the shielding of the “target component” defines this energy). Finally, for evaluation of single event effects, the environment also has to be described in terms of the LET spectrum in order to predict rates on the basis of test data. These LET spectra describe brief high-flux periods, but also longer term averages. All these SEP effects have to be seen alongside other causes of radiation effects. While for missions beyond the magnetosphere, the SEP component is the strongest in terms of radiation dose, within the Earth’s magnetosphere effects tend to be dominated by radiation belts. Even in interplanetary space, the softness of the SEP energy spectrum relative to cosmic rays can means that they can be often be shielded against.
4	Radiation belt environment and effects evaluation during design	Evans, H et al.	p-Poster
	Hugh Evans
	Rhea System BV, ESA
	An overview of the process used to define a space environment specification for ESA missions and radiation effects mitigation strategies and margin policies will be presented. These processes minimise the risk of mission failure due to environmental concerns to a level appropriate for the mission profile without excessive costly over design.