# Presentation: 514200

## Presentation at Living With a Star Workshop
R. A. Hoffman
B. L. Giles

- R. A. Hoffman
- B. L. Giles

## Mission Objectives

- with special emphasis on penetrating radiation during geomagnetic storms

- Acquire the data required for the development of empirical and science-driven radiation belt models

- Acquire the data for real time telemetry needed by the operations community

- Obtain scientific understanding of the sources, transport and losses of radiation belt particles

## Measurement Goals

- Coverage of full phase space distributions over local time and altitude
- Electric and magnetic fields characterizations over frequency domain of interest to the radiation belts

- Data products for specification and predictive models
- Data products for real-time telemetry for the operations community

**Science Community**

**User Community**

## Phases of the Program

- Targeted data analysis activities
- Development of modeling techniques and procedures
- Instrument development activities

- Launch about 2008
- Two year lifetime, five year goal
- Data analysis

- TBD missions
- TBD instrumentation

**First phase:**  utilization of current and near future missions

**Second phase:**  primary flight phase

**Third phase:**  targeted flights to characterize radiation belts

## Disclaimer

- The Radiation Belt Mapper mission scenario to be presented represents one possible approach.
- Other approaches are possible and should be studied during the formal definition phase.

- Therefore nothing to be presented should be considered definitive.

## Bounds of Responsibility

- Substorm effects included only as input to radiation belts
- Input to radiation belts from beyond geosynchronous orbit provided by non-LWS programs
- Polar cap precipitation measurements:
- 		Galactic cosmic ray intensities are domain of Sentinels
- 		Solar cosmic ray characteristics are domain of Sentinels
- Auroral precipitation is domain of Ionospheric Mappers
- Geomagnetic cutoff latitudes for galactic and solar cosmic rays is task of Sentinels and modeling
- South Atlantic anomaly is domain of RBM with instrumentation possibly carried by Ionospheric Mapper spacecraft
- Radiation belt precipitation is domain of RBM with instrumentation possibly carried by Ionospheric Mapper spacecraft

**Bounds of Responsibility**

## RBM Pre-Formulation Activity Timeline

- February 15      Started with a clean slate
- March 9            Pre-Formulation Definition Team Meeting
- March 13-15     Integrated Mission Design Center (IMDC)
- March 20-23     Space Weather Conference in Florida
- April 20             Resources Analysis Office results
- May 2                Space Weather Week in Boulder
- May 8 & 9         Return to IMDC
- May 10 - 12       LWS Workshop

## Pre-Formulation Definition Team

## Products of Definition Team

-  Requirements definition
-  Requirements evaluation
-  Candidate orbit scenarios
-  Instrumentation parameter tables
-  Orbit evaluation approach

## Requirements Evaluation - part 1

-  Parameter (e.g.):
-      Proton fluxes
-      Electron fluxes
-      Heavy ions
-      Waves
-      E fields

-  Regions:
-      Inner belt
-      Slot belt
-      Plasmasphere
-      Outer belt, inc. ring current

-   Purpose
-  Priority:
-      Users
-      Science

**Actual chart is available as separate file: RBM_requirements.pdf**

## Requirements Evaluation - part 2

-  L value range
-  Type of distribution

**Requirements Evaluation - part 2**

-  Temporal resolution
-  Local time resolution

**Actual chart is available as separate file: RBM_requirements.pdf**

## Requirements Evaluation

-  Parameter (e.g.):
-      Proton fluxes
-      Electron fluxes
-      Heavy ions
-      Waves
-      E fields

-  Regions:
-      Inner belt
-      Slot belt
-      Plasmasphere
-      Outer belt, inc. ring current

-   Purpose
-  Priority:
-      Users
-      Science

** **Parameter:  range (e.g., energy), resolution
-  L value range
-  Type of distribution
-  Temporal resolution
-  Local time resolution

## Candidate Orbits - part 1

- Inner and outer sets of petals precess differentially with LT
- Greater distribution in radial distance and local time

- All candidate orbits have an additional spacecraft with 2.8 Re apogee for inner belt  and slot observations

- 6 S/C on 3 Nested Petals

- 6 S/C on 3 Petals

- 4 semi-radial cuts per period
- Higher time resolution for  L distribution

- Inclinations _<_12°

## Candidate Orbits - part 2

- All precess differentially with local time
- Simple orbit insertion

- With minimal station keeping, petals remain evenly spaced in local time
- Affords better local time distribution
- Radial cuts in same direction simultaneously, with station keeping

- 6 S/C on 6 Even Petals

- 5 S/C on 5 Nested Orbits

**Candidate Orbits - part 2**

- Inclinations _<_12°

## Evaluation of Candidate Orbits

- Work in progress
- Need for one or more of the spacecraft to be at intermediate inclination remains an open issue
- Nested option eliminated upon initial evaluation
- Initial IMDC and RAO results discouraged further evaluations
- Current launch approach does not eliminate remaining candidates

## Spacecraft Requirements

- Sun pointing within ~15
- Identical spacecraft
- Standard aerospace manufacturing/fabrication  practices (ideal for industry participation)
- Two-year lifetime, five year goal
- High radiation environment
- Continuous downlink for real-time telemetry
- Full instrument complement on each spacecraft

**Spacecraft Requirements**

## Candidate Instruments in Priority Order

- 	Mid-energy particles (30 keV to 1 MeV)
- 	Very high energy protons (20-500 MeV) on low apogee spacecraft
- Flux gate magnetometer
- Electric field probes (2 orthogonal axes in spin plane)
- Low energy ions and electrons (30 eV - 30 keV)
- 	Option: include mass analysis
- Search coil magnetometer
- Thermal plasmas density and temperature (< 100 eV)
- 	Option:  include energy and mass analysis

**Candidate Instruments in Priority Order**

## Constraints Imposed on Feasibility Study

- Launch from U.S. launch site
- Use of single Delta II or equivalent in cost
- Spacecraft components currently available or available near term
- Instruments available today
- Full environmental testing on all copies
- Cost analysis based on past history
- Cost analysis based on no commonality with other LWS missions

**Constraints Imposed on Feasibility Study**

## Mass to Orbit via Single Vehicle

- Launch vehicle puts all spacecraft in 500 km x 8400 km, 28° inclination orbit
- Low-apogee and first high-apogee spacecraft are boosted to correct apogees and 12° inclination
- Orbital precession moves the local time of apogee for the remaining satellites with respect to the first satellites
- As each remaining spacecraft moves to the correct local time, it is boosted to the final apogee and its inclination is changed to 12°
- Insertion technique applicable to all candidate orbit configurations

## Possible Spacecraft Design

**Possible Spacecraft Design**

- Mission unique spacecraft design
- Radiation shielding and stacking requirement precludes use of RSDO
- Baseline materials to be composite
- Few new manufacturing/fabrication techniques, standard aerospace practices    (ideal for industry participation)
- Hinged magnetic field booms
- Deployable electric field antennas
- No unusual integration difficulties

- Not all subsystems shown in this view

## Possible Experiment Layout

- E-Field Probe

- E-Field Probe

- Magnetometer

- E-Field Probe

- Low Energy

- E-Field Probe

- Search Coil

- Mid Energy

- Propulsion
- Tanks

**Possible Experiment Layout**

- High energy particle telescopes not shown in this view

- Not all subsystems shown in this view

## Spacecraft accommodation on launch vehicle

- Delta II 7920H-10 and Delta IV considered for pre-formulation study
- Volume and placement not a constraint for either launch vehicle
- Launch from Kennedy
- No unusual appendices caging requirements
- No unusual integration difficulties
- No unusual deployment procedure

- Not all subsystems shown in this view

## Comparison Between 

**Comparison Between **
**Definition Team Program and Definition Study**

## RBM Challenges - Part 1

- Develop core mission scenario based on realistic assessment of technological advances in the next few years, that
- 	a)  avoids current single source suppliers
- 	b)  allows concrete basis for cost estimates.
- Find affordable launch scenario that maximizes number of spacecraft on single launch vehicle and achieves minimum inclination (at least for some spacecraft).
- Develop concepts for acquisition of instruments, with calibrations, testing, software development for operations and data processing, post-launch instrument validation, operations and data processing while minimizing staffing.
- Develop concepts for fabrication and calibration of multiple copies of instruments while minimizing costs.

## RBM Challenges - Part 2

- Develop concepts for fabrication and testing of multiple copies and integration of spacecraft while minimizing costs.
- Develop environmental testing approach for multiple, identical spacecraft that would assure reliable spacecraft and instruments while minimizing testing costs.
- Evaluate, especially with Ionosphere Mappers mission, spacecraft systems commonalities
- Seek partnering to acquire:
- 	a)  additional launch opportunities for spacecraft
- 	b)  flights of opportunity for instruments
- 	c)  complementary spacecraft missions