# Presentation: 514199

## Presentation at Living With a Star System Architecture Team Meeting
R. A. Hoffman
B. L. Giles

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

## Mission Objectives

**Mission Objectives**

- Acquire the measurements necessary for the development of specification models and validation of physics-driven radiation belt models

## Pre-Formulation Definition Team

**Pre-Formulation Definition Team**

## 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**

## Scope of the Mission

- South Atlantic anomaly
- Radiation belt precipitation
- Input to radiation belts from beyond geosynchronous orbit provided by non-LWS programs (e.g., STP/Magnetosphere Constellation)
- Galactic and solar cosmic rays are task of Sentinels with geomagnetic cutoff latitudes being task of modeling
- Auroral precipitation is domain of Ionospheric Mappers

**Scope of the Mission**

## 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

## Requirements table inserted here ...

## Example Candidate Orbits

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

- 6 S/C on 3 Petals

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

- Inclinations _<_12°

- Petals evenly spaced in local time
- Emphasizes local time distribution
- Radial cuts in same direction simultaneously

- 6 S/C on 6 Even Petals

## 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**

## Suggested Near-Term Tasks

-  Review requirements parameters table
-  Further prioritize requirements
-  Develop better criteria for evaluation of candidate orbits
-  Review spacecraft requirements

**Longer-Term Tasks**

-  Obtain further input on instrument developments
-   Re-cost modified program with RAO

## RBM Issues

- Prioritize requirements to:
- 	a)  optimize the number and distribution of spacecraft
- 	b)  assess the complement of instruments on each spacecraft
- 	c)  determine utilization of remote sensing techniques and missions
- Seek partnering:
- 	a)  with complementary spacecraft missions
- 	b)  to acquire additional launch opportunities for spacecraft
- Develop core mission scenario based on realistic assessment of technological advances in the next few years
- Minimize costs
- mitigate impact of severe radiation environment
- develop new concepts for instrument and spacecraft acquisition
- evaluate risk of reduced environmental testing of multiple copies
- identify commonalities between missions
- Identify need for inclusion of auroral imaging within LWS
- Ascertain responsibility for real-time telemetry, collection and distribution

## Supplementary Material

## 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 presented should be considered definitive.

## 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

## Products of Pre-Formulation Definition Team

-  Definition of parameters, ranges, accuracies
- Prioritization of parameters, independently for science and users
-  Development of four candidate orbit scenarios
-  Initial evaluation of orbit scenarios
-  Specifications of spacecraft requirements
-  Identification of candidate instruments with priorities

## Example Candidate Orbits

- All precess differentially with local time
- Simple orbit insertion

- 5 S/C on 5 Nested Orbits

**Example Candidate Orbits**

- Inclinations _<_12°

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

- 6 S/C on 3 Nested Petals

## 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**

## 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**