GROUP F EFFECTS ON INSTRUMENTS,

SPACECRAFT & COMMUNICATIONS

Eamonn Daly and Jim AdamsEamonn Daly and Jim Adams

Effects ConsideredEffects Considered• Single Event Effects in Electronics Single Event Effects in Electronics

• Total Radiation Dose to ComponentsTotal Radiation Dose to Components

• Single Event Effects in SensorsSingle Event Effects in Sensors

• Radiation Damage to Sensors including activationRadiation Damage to Sensors including activation

• Radiation Damage to Solar cellsRadiation Damage to Solar cells

• Space Weather Effects on CommunicationsSpace Weather Effects on Communications

• Electrostatic ChargingElectrostatic Charging

Requirements for Models Requirements for Models Radiation BeltsRadiation Belts

• Replacement of AE8, AP8 (static models)– This is needed for:

• SEE (inner belt protons)• Total dose (outer belt electron long term averages)• (Deep) electrostatic charging (outer belt short term variations)• Sensor background (short and long term variations)

• Models must provide history of variations on various timescales – solar cycle, months, days, hours, minutes

• Example: POLE model (electrons at GEO)

Requirements for Models Requirements for Models PlasmaPlasma

• Spacecraft charging environments– short term variations

e.g. Mars mission architecture foresees the transit vehicle parked at GEO.

Requirements for ModelsRequirements for ModelsSPEsSPEs

• Need a debate on which are the most appropriate models and methods, involving all disciplines

• Approaches include:– 4 x August72– ‘Oct 89– Feb ‘56– Risk-based models– Data-based analysis (long records)

• Need heavy ion models (flux and fluence energy spectra)• ISO Standards activities need more community involvement• Need helio-radial dependence of flux and fluence

Requirements for Models Requirements for Models Space WeatherSpace Weather

• Nowcast more important (and expected to be more reliable) than forecast;

• Prediction of SPE occurrence and expected time profile (at vehicle location);

• All clear (resume normal operations);• Autonomous/crew situational awareness and operation

of vehicles;• Utilization of long-term space weather datasets for

design/modeling/operations– Quality control– Validation– Synthesis into design tools

Single Event Effects ModelsSingle Event Effects Models• Replace CREME96 (CREME is a tool combining GCR,

SEP and error rate prediction)– Improve solar particle models– Update GCR model including correct solar cycle modulation of

composition• SEE prediction method improvements, addressing:

– geometry complexity– decreasing feature size– track effects– single event transient effects

• Implement physics-based modeling– particle interactions + device physics

TestingTesting• We expect a large demand due to the use of COTS parts & systems• Exisiting Facilities:

– Tandem 20m @ 300MeV (too low, need de-lidding and vacuum, but fast to use)

– Berkley 88 inch (Aerospace): better range but still need de-lidding, vacuum; – TexA&M K1200; higher range (need de-lidding and thinning)– Mich State 2 x K1200 ; no de-lidding necessary (50-200MeV/nuc); more

costly – NASA (NSRL) Ion Beam Facility Brookhaven (50-200MeV/nuc); Access

policies are oriented toward scientific investigators, e.g.:• Peer reviewed life sciences proposals• Preliminary data for intended proposers to NASA calls• Non-life-science NASA experiments (not charged for small amounts)• Some new proposal process or executive decision is needed for

engineers to gain effective access.– Quality Control

• Major IssueMajor Issue: engineering tests need to be implemented for Exploration Program

FindingsFindings• Availability of and access to adequate external accelerator

beams needs to be assured though agreement with DOE• Revision of the radiation effects prediction tools is needed• Improved models of proton and heavy ion environments in

SEPs are needed• On-orbit testing is needed for critical system tests and model

validation• A suitable radiation environment monitor needs to be

included on each NASA mission so radiation effects can be diagnosed.

• New tools will be needed for forecasting space environmental conditions on Mars missions

• NASA needs to ensure that the communities represented at this meeting continue to work together

Backup ChartsBackup Charts

Solar activity can effect Solar activity can effect instrumentation, spacecraft and instrumentation, spacecraft and

communications by:communications by:– degrading solar cellssolar cells– affecting electronics electronics primarily by single event

effects caused by protons and heavy ions– interfering with sensorssensors by both direct ionization

and activation of the sensor or surrounding materials

– direct ionization interferes with solid state cameras

– degrading optical and thermal control surfacessurfaces– ActivationActivation of gamma ray spectrometers

IssuesIssues• Critical systems

– Life support– communications, – Navigation and guidance (incl. launch)– In-situ resource systems

• Lunar Infrastructure – Communications, navigation, beacons– Local environment measurements (instruments for

geology)• Technology Evolution

– Analysis and testing problems

Points DiscussedPoints Discussed• Missions

– LRO– CEV– Other lunar reconnaissance missions– Infrastructure elements– Mars missions

• Technologies– COTS components– FPGAs– Testing– Critical systems

• Technology trends• Need for precursor technology

missions• Monitors and in-orbit test-beds• Forecast vs. hardening

• Effects Review– Total radiation dose to components– Radiation damage to solar cells– Radiation damage to sensors– Single event effects in electronics– Single-event effects in sensors – Electrostatic charging– Space weather effects on

ionosphere/thermosphere • Requirements for engineering

models– Radiation belts– Magnetospheric plasma– Solar energetic particles– Cosmic rays– Space weather– SEE models

Missions and ElementsMissions and Elements• LRO (2008)

– Includes CRATER instrument– Includes precise remote sensing of

topology and composition (various spectrometry)

– GNC on board critical system– “today’s” technology

• LRO 2-5? (2010-2016?)– Landers with rover? Permanently

shadowed craters;• CEV

– CEV-mark 1 – manned but limited for ISS

– CEV-for lunar = same + polyethylene (will be left unmanned and operate autonomously 6 months)

– Partially re-used– CEV variant for Mars crew transfer

• CEV-derived cargo carrier– pressurized, – unpressurized

• Lunar manned missions – Parked in LEO for up to 1 month; 2

weeks on lunar surface; – Lunar rover – Lunar bases

• long-term or permanent• long-term damage and system effects• Surfaces damaged• “Earth-moving” equipment

• Infrastructure elements – further downstream (permanent?) –

habitats, communications, navigation, power

• Mars missions– 1998 reference mission– Stored at GEO/high altitude; transfer by

CEV;– More complex architecture – more to go

wrong• Launchers – heavy launcher

– restartable upper stage – critical– Diagnostic imaging

TechnologiesTechnologies• Strategy for CEV will be to use proven technologies

(2008 flight test CEV)• But (for example)

– COTS components will be widespread– FPGAs– MEMS– RTGs?– Hard drives– Systems on chips– Multi-junction solar cells

• In many critical systems• All imply needs for considerably improved methods for

– testing – prediction – hardening by design (& fault tolerant systems)

Technology TrendsTechnology Trends• Many more critical systems• Increasingly difficult to test realistically• Procurement of at unit level

(GPS, laptops…)• Component Issues

– Scaling• 90nm – 65 nm – 45 nm (18mths) …?

– Gb DRAMs;– Low Voltage– Speed multi GHz– Materials: Cu tracks; oxides; non-Si devices;– Packaging;– Rad hard cmos; secondaries;– Optoelectronics; mixed signal systems;

Needs for Precursor Missions, Needs for Precursor Missions, Test-beds and MonitoringTest-beds and Monitoring

• Flight test complete critical systems in relevant orbits before undertaking (in particular) human Lunar (Mars) missions;

• Exploration test-bed program should follow the LWS SET and New Millennium programs;

• Monitors (at least simple sensors, dosimeters) should be flown on all spacecraft;

Forecasts vs. HardeningForecasts vs. Hardening• Critical systems:

– Operate-through requirement (harden)• Non-critical :

– Shut down to prevent damage• Sensor safeing needed

– No critical actions during high background events– Spurious signal handling– Instrument closure

• Generally, the engineering approach is to harden systems against worst cases

• Exceptions always appear; late implementation of protective operational measures will inevitably occur

Total Radiation Dose to ComponentsTotal Radiation Dose to Components

• Lunar missions– Lunar delivery: radiation belts (fast vs. slow transits)– Short-term state of radiation belt;

• Mars Missions– R>1AU– SPE helioradial variation models– Elements parked for long periods in Earth orbit

• Generic Needs– SPE risk models; – Tools for component dose prediction

Radiation Damage to Solar cellsRadiation Damage to Solar cells

• Lunar missions– Lunar delivery: radiation belts (fast vs. slow transits)– Short-term state of radiation belt;

• Mars Missions– R>1AU– SPE helioradial variation models – Elements parked for long periods in Earth orbit

• Generic Needs– SPE risk models; – Tools for prediction in multi-junction cells

Radiation Damage to SensorsRadiation Damage to Sensors

• Lunar missions– Lunar delivery: radiation belts (fast vs. slow transits)– Short-term state of radiation belt;

• Mars Missions– R>1AU– SPE helioradial variation models– Elements parked for long periods in Earth orbit

• Generic Needs– SPE risk models; – Tools for prediction of sensor damage

Single Event Effects in SensorsSingle Event Effects in Sensors

• Lunar missions – LEO/transit protons;– GCR; SPE; Predictions;

• Mars Missions– SPE helioradial variation models– Predictions– Elements parked for long periods in Earth orbit

• Generic Needs– Event data; – data-based analysis (non-extreme events);

Single Event Effects in ElectronicsSingle Event Effects in Electronics

• Lunar missions– LEO/transit protons;– GCR; SPE; Predictions;

• Mars Missions– SPE helioradial variation models– Albedo n environment – Predictions– Elements parked for long periods in Earth orbit

• Generic Needs– Event data; Energy spectra (not just LET)– data-based analysis (non-extreme events); – tools for modern devices

Space Weather Effects on Space Weather Effects on Ionosphere/ThermosphereIonosphere/Thermosphere

• Lunar missions• Mars Missions• Generic Needs

– Optical and other comms

Electrostatic ChargingElectrostatic Charging

• Lunar missions• Mars Missions• Generic Needs

– Radiation belt transits;– Dynamic models; – Predictions;

Neutron (SEE) EnvironmentsNeutron (SEE) Environments

• Heavily shielded elements will have relatively significant neutron flux;

• Neutron albedo models for Mars (incl. Atmosphere, regolith, sub-surface H2O);

• Current capabilities probably sufficient

Requirements for Models Requirements for Models GCRGCR

• Not a strong requirement in this area• Updates of energy spectra, composition

and solar cycle variations based on ACE data

• H, He from other sources

TestingTesting• Exisiting Facilities:

– Tandem 20um 300MeV @ (too low, need de-lidding and vacuum, but fast to use)– Berkley 88 inch (Aerospace): better range but still need de-lidding, vacuum; – TexA&M K1200; higher range (need de-lidding and thinning)– Mich State 2 x K1200 ; no de-lidding necessary (50-200MeV/nuc); more costly

• NASA (NSRL) Ion Beam Facility Brookhaven– Mono-energetic beams 50MeV -> few GeV/nuc; – Representative for electronics (incl. appropriate LET spectrum)– Simulated cosmic ray spectrum available in ~1 yr– 34M$; 1200hr/yr; ~100 groups; – European and Japanese groups within context of reciprocal agreements– Priority (regular solicitations):

• Peer reviewed life sciences proposals• Preliminary data for intended proposers to NASA calls• Parasitic experiments (no payment)• Non-life-science NASA (not charged for small amounts)

– Quality Control– “Mission Critical” type applications carefully scrutinized

• Major IssueMajor Issue: engineering tests - need to be implemented for Exploration Program

Main FindingsMain Findings• NASA needs to ensure the availability of and access to

adequate external particle beams for SEE testing;• NASA needs to support revision of the radiation effects

prediction tools;• NASA needs to provide improved models of proton and

heavy ion environments in SEPs;• NASA needs to provide facilities for on-orbit testing, including

critical system tests and model validation;• NASA needs to provide new tools for forecasting space

environmental conditions for the Mars mission;• NASA needs to ensure that all communities involved

continue to work together in this area;• NASA needs to include the means of acquiring a minimum

set of information on the space environment on each of its missions