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height="1.2807086614173229in"}

> **Geospace -Radiation Belt Storm Probes**
>
> **(G-RBSP)**

**Level 2 - Science and Mission Requirements Document**

**(SMRD)**

**Effective Date: xx/xx/xx\
Expiration Date: xx/xx/xx**

**CM FOREWORD**

This document is a Radiation Belt Storm Probe (RBSP) Project
Configuration Management (CM)-controlled document. Changes to this
document require prior approval of the applicable Configuration Control
Board (CCB) Chairperson or designee. Proposed changes shall be submitted
to the RBSP CM Office (CMO), along with supportive material justifying
the proposed change.

In this document, a requirement is identified by "shall," a good
practice by "should," permission by "may" or "can," expectation by
"will," and descriptive material by "is."

Questions or comments concerning this document should be addressed to:

G-RBSP Configuration Management Office

Mail Stop 466

Goddard Space Flight Center

Greenbelt, Maryland 20771

**Signature Page**

+-----------------------------------+----------------------------------+
| ***Prepared by:***                |                                  |
+-----------------------------------+----------------------------------+
| \_\_\_\_\_\_\_\_\_                | \_\_\_\_\_\_\_                   |
|                                   |                                  |
| Nicholas Speciale                 | David Sibeck                     |
|                                   |                                  |
| G-RBSP Project Mission System     | G-RBSP Project Scientist         |
| Engineer                          |                                  |
|                                   | NASA-GSFC Code 674               |
| NASA-GSFC Code 599                |                                  |
|                                   | \_\_\_\_\_\_\_\_\_\_\_\_         |
| \_\_\_\_\_\_\_\_\_\               | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
| _\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ | \_\_\_\_\_\_                     |
| \_\_\_\_\_\_\_\_\_                |                                  |
|                                   | Barry Mauk                       |
| Doug Eng                          |                                  |
|                                   | G-RBSP Mission Scientist         |
| G-RBSP Mission System Engineer    |                                  |
|                                   | JHU-APL                          |
| JHU-APL                           |                                  |
|                                   | \_\_\_\_\_\_\_\_\_\_\_\_\_       |
| \_\_\_\_\_\_\_\_\_\_\             | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
| _\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ | \_\_\_\_\_\_\_                   |
| \_\_\_\_\_\_\_\_                  |                                  |
|                                   | Nicola Fox                       |
| Joseph Grebowsky Code 695         |                                  |
|                                   | G-RBSP Deputy Mission Scientist  |
| G-RBSP Project Deputy Project     |                                  |
| Scientist                         | JHU-APL                          |
|                                   |                                  |
| NASA-GSFC Code xxx                | \_\_\_\_\_\_\_\_\_\_\_\_\_       |
|                                   | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|                                   | \_\_\_\_\_\_\_                   |
|                                   |                                  |
|                                   | Kazue Takahashi                  |
|                                   |                                  |
|                                   | G-RBSP Science Team              |
|                                   |                                  |
|                                   | JHU-APL                          |
+-----------------------------------+----------------------------------+
| ***Reviewed and Concurred by:***  |                                  |
+-----------------------------------+----------------------------------+
| \_\_\_\_\_\_\_\_\_                | \_\_\_\_\_\_\_\_\_ \<Nicholas J. |
|                                   | Speciale\> Date                  |
| \<David Sibeck\> Date             |                                  |
|                                   | \<G-RBSP Project Mission System  |
| \<G-RBSP Project Scientist\>      | Engineer\>                       |
|                                   |                                  |
| \<NASA-GSFC Code 674\>            | \<NASA-GSFC Code 599\>           |
+-----------------------------------+----------------------------------+
| ***Approved by:***                |                                  |
+-----------------------------------+----------------------------------+
| \_\_\_\_\_\_\_\_\_                | \_\_\_\_\_\_\_\_\_ Mary DiJoseph |
|                                   | Date                             |
| \<Timothy Gehringer\> Date        |                                  |
|                                   | LWS Program Manager              |
| \<G-RBSP Project Manager\>        |                                  |
|                                   | Code 460                         |
| \<Code 466\>                      |                                  |
+-----------------------------------+----------------------------------+
|                                   |                                  |
+-----------------------------------+----------------------------------+

![](media/image2.pct){width="1.0416666666666666e-2in"
height="1.0416666666666666e-2in"}**GEOSPACE -- RADIATION BELT STORM
PROBES (G-RBSP)**

**DOCUMENT CHANGE RECORD**

+-------+-------------------------------------------+---------+--------+
| Ve    | DESCRIPTION OF CHANGE                     | CCR No. | Date   |
| rsion |                                           |         |        |
| or    |                                           |         | Ap     |
| Rev   |                                           |         | proved |
| ision |                                           |         |        |
| Level |                                           |         |        |
+-------+-------------------------------------------+---------+--------+
| 0.1   | Initial Phase "A" draft version for       | N/N/    | 3      |
|       | comment to SWG, HQ, LWS Program and       |         | -16-07 |
|       | G-RBSP Project (GSFC) and Mission teams   |         |        |
|       | (APL).                                    |         |        |
+-------+-------------------------------------------+---------+--------+
|       |                                           |         |        |
+-------+-------------------------------------------+---------+--------+

**TABLE OF CONTENTS**

**TBS**

[Page]{.underline}

**1.0** **Introduction**

**[The G-RBSP mission will provide scientific understanding, ideally to
the point of predictability, of how populations of relativistic
electrons and ions in space form and change in response to variable
inputs of energy from the Sun.]{.mark}**

[]{.mark}

[A two-year mission to the inner magnetosphere- Earth's natural particle
accelerator region- offers local time, altitude and geomagnetic activity
coverage sufficient to sample a wide range of energetic particle events,
to identify the underlying physical processes that accelerate,
transport, and cause the loss of energetic particles, and to determine
their relative significances and interaction modes. In addition, the
mission will quantify the time-varying structure and processes of the
inner magnetosphere, identify source populations, and determine when and
where relevant plasma waves are generated.]{.mark} The G-RBSP mission
will provide a comprehensive understanding of fundamental processes that
operate throughout the plasma universe, including both magnetized and
unmagnetized planets, the solar wind, our Sun and other stars. It will
provide the knowledge needed to develop both empirical and predictive
models that can be used to safeguard astronauts and spacecraft in
near-Earth orbit and future exploration missions to Mars and the other
planets.

Discriminating between proposed interaction mechanisms and
distinguishing between energetic charged particle source and loss
regions and their spatial extents requires simultaneous observations
over a wide range of spacecraft separations. To accomplish this task,
the G-RBSP mission will operate two Earth-orbiting spacecraft in nearly
identical eccentric orbits that lap one another several times over the
nominal two-year mission lifetime. The orbits of the spacecraft must be
near-equatorial to observe full particle pitch angle distributions with
respect to the magnetic field within the radiation belts. The
instruments must make charged particle observations over energies
ranging from those of the source population (as low as 1 eV) to those
representative of the most energetic particles within the radiation
belts ([2 GeV]{.mark}). Distinguishing between source populations,
identifying the predominant contributors to the ring current, and
understanding wave-particle interaction modes requires ion composition
measurements over energies ranging from 1 eV to 1000 keV. Understanding
the transport and energization of relativistic particles within the
inner magnetosphere requires observations of the DC electric and
magnetic fields. Identification of wave-particle interaction modes that
lead to both particle acceleration and loss requires observations of
electric and magnetic field waves over the full range of frequencies
capable of interacting with particles (nominally, 10 Hz to 10 kHz for
the Earth's inner magnetosphere). Finally, plasma densities governing
the structure of the inner magnetosphere are best determined from
observations of the spacecraft potential and plasma waves to 500 kHz.

  ----------------------- ----------------------- -----------------------
  Particle Instrument                             
  Capability                                      

  Parameter               Energy Level            Energy Range

  Electron Spectra        Low                     Few eV - \~50 keV

                          Medium                  \~40 keV -- 4 MeV

                          High                    2 MeV -- 10 MeV

  Ion Composition         Low                     Few eV - \~50 keV

                          Medium                  \~45 keV -- 400 keV

  Proton Spectra          Medium                  15 keV -- 8-10 MeV

                          High                    5-8 MeV - \> 100 MeV

                          Very High               100 MeV -- 2 GeV
  ----------------------- ----------------------- -----------------------

  ----------------------- ----------------------- -----------------------
  Fields & Waves                                  
  Instrument Capability                           

  Parameter               Frequency Level         Frequency Range

  DC Magnetic field       Low frequency           DC - \~ 30 Hz

                                                  

  AC Magnetic field       Low frequency           Quasi-static -- 10 Hz

                          High frequency          10 Hz -- 12 kHz

  DC Electric field       Low frequency           DC -- 12 Hz

                                                  

  AC Electric field       Low frequency           10 Hz -- 12 kHz

                          High frequency          10 kHz - 500 kHz
  ----------------------- ----------------------- -----------------------

[The measurement requirements for the G-RBSP mission will be met by
combining observations made by the following investigations:]{.mark}

[]{.mark}

1.  [The Energetic Particle, Composition and Thermal Plasma Suite. This
    investigation was selected to]{.mark} calculate adiabatic invariants
    in storm-time fields, determine dynamic phase space density
    profiles, differentiate the causes of particle acceleration
    mechanisms, understand the production of plasma waves, determine how
    the inner magnetospheric plasma environment controls particle
    acceleration and loss, and characterize source particle populations
    and their transport. . The investigation will provide a complete
    complement of data analysis techniques, case studies, theory,
    modeling, and auxiliary measurements along with expertise to
    delineate particle acceleration mechanisms, radiation belt particle
    enhancement and loss, and how the near-Earth environment controls
    those acceleration and loss processes.

2.  [The Electric and Magnetic Field Instrument Suite and Integrated
    Science (EMFISIS) on Radiation Belt Storm Probes]{.mark} will
    determine the origin of important plasma wave classes and their role
    in particle acceleration processes. The investigation will also
    quantify the evolution of the magnetic field that defines the basic
    coordinate system controlling the structure of the radiation belts
    and the storm-time ring current. EMFISIS will provide calculation of
    onboard spectra, including spectral matrices, making it possible to
    determine wave normal angles and Poynting fluxes for the plasma
    waves of interest and providing information for wave mode
    identification and propagation modeling which are essential for
    understanding and modeling of radiation particle physics.

3.  [Electric Field and Waves (EFW) Instrument.]{.mark} The
    investigation was selected to provide understanding of the electric
    field properties associated with particle energization, scattering
    and transport, and the role of the large-scale convection electric
    field in modifying the structure of the inner magnetosphere. EFW
    measurements of the spacecraft potential will define the ambient
    plasma density.

4.  [Radiation Belt Science of Protons, Ion Composition, and Electrons
    (RB-SPICE).]{.mark} This investigation was selected to accurately
    resolve the ring current pressure distribution needed to understand
    how the inner magnetosphere changes during geomagnetic storms and
    how that storm environment supplies and supports the acceleration
    and loss processes involved in creating and sustaining hazardous
    radiation particle populations.

5.  The Proton Spectrometer Belt Research (PSBR) This investigation will
    determine the upper range of proton fluxes in the inner
    magnetosphere and develop and validate models of the Van Allen
    radiation belts.

[]{.mark}

An immediately useful application of the measurements and new scientific
understanding will be the generation of both physics-based and empirical
models for the Earth's radiation belt environment. However, the
understanding gained from studying basic processes operating within the
Earth's inner magnetosphere can also be applied at more inaccessible
locations throughout the heliosphere and plasma universe.

1.  **Purpose**

This document defines the Level 2 scientific objectives, measurements
and derived mission requirements for the Geospace - Radiation Belt Storm
Probe Project.(RBSP)

Geosp![](media/image3.png){width="4.86875in" height="2.6125in"}ace-

Figure 1.1 shows the current G-RBSP Project and Mission level document
tree and the placement and ownership level of this document.

2.  **Document Organization**

KEY NOTE: Sections 1-3 of this document provide only contextual and
background information for understanding the scientific and mission
needs and objectives of G-RBSP Project. There are no specific
requirements or "shall statements" in these sections. Section 4 of this
document provides the actual G-RBSP Science and Mission Requirements and
contains all full requirements or "shall statements" This section is
currently in Excel spreadsheet form and will be eventually imported into
text form when the proper maturity level has been achieved.

This G-RBSP Project Level 2 Science and Mission Requirements Document
(SMRD) is organized as follows:

Section 1 of this document provides an introduction and background for
science needs and goals of the G-RBSP Project.

Section 2 of this document provides a summary overview of the eight
G-RBSP specific objectives and the needed observations and measurements
to satisfy each objective. As stated above, information in this section
is contextual only, there are no specific requirements in this section.

Section 3 of this document provides an overview and summary of key
mission level needs derived G-RBSP science objectives. Again, this
section only provides contextual information

Section 4 of this documents provides the baseline Level 2 G-RBSP Science
and Mission Requirements that provides traceability to the LWS Program
Level 1 Requirements (Appendix x of LWS Program Plan). This section
flows down requirements to the RBSP Project (JHU/APL) Mission
Requirements Document.

Appendix "A" of this document provides the comprehensive and detailed
derivation and traceability of the science measurements needed to meet
each of the eight G-RBSP scientific objectives. As such this section
provides the analytical foundation and validation basis for each of the
measurement requirements that are in incorporated Section 4 of this
document.

3.  **G-RBSP Investigations**

> As a result of the G-RBSP investigations Announcement of Opportunity
> (NNH05ZDA003O), four investigations were selected. These are:

1.  The Energetic Particle, Composition, and Thermal Plasma Instrument
    Suite (ECT), Boston University,

2.  The Electric and Magnetic Field Instrument Suite and Integrated
    Science (EMFISIS) , University of Iowa,

3.  The Electric Field and Waves Instrument (EFW), University of
    Minnesota, and

4.  The Radiation Belt Storm Probes Ion Composition Experiment
    (RB-SPICE), NJIT

5.  The Proton Spectrometer Belt Research (PSBR), NRO

The ECT investigation will supply three instruments: HOPE, MagEIS, and
REPT. Helium Oxygen, Proton Electron (HOPE) is an electrostatic energy
analyzer and time of flight mass spectrometer that measures [low
energy]{.mark} electrons and ion species (H+, He+, and O+) versus energy
and angle. Magnetic Electron Ion Spectrometer (MagEIS) is a set of four
energetic particle magnetic spectrometers that simultaneously measures
[medium energy]{.mark} electrons and ions over three different energy
ranges and two different directions. Relativistic Electron Proton
Telescope (REPT) is a solid-state detector based particle telescope that
measures [very high energy]{.mark} electrons and protons. All three
instruments rely upon a spacecraft spin axis nearly perpendicular to the
local magnetic field to observe a nearly full range of particle pitch
angles relative to the magnetic field once per spin.

The EMFISIS investigation will supply two instruments: MAG and WAVES.
The Magnetometer (MAG) is a triaxial fluxgate magnetometer that measures
the 3 components of the ambient steady and low frequency variations in
the magnetic field. The WAVES is a triaxial search coil magnetometer
that measures the 3 components of the magnetic field, and a set of
waveform receivers the provides the 3 components of the electric field
over higher frequencies.

The EFW investigation will supply an instrument comprised of three
electric field sensor pairs on three paired, orthogonal boom sets, two
pairs that measure the two dimensional electric field in the plane
normal to the spacecraft spin axis and one pair that measures the
electric field component along the spacecraft spin axis. EFW will also
provide spacecraft electric potentials.

The RBSPICE investigation will supply a time-of-flight by energy (TOFxE)
instrument that measures and discriminates between H, He,and O ring
current ions. The instrument provides nearly complete pitch angle
coverage once each spin.

The PSBR investigation will supply one instrument for each observatory.
The Relativistic Proton Spectrometer (RPS) instrument is a combined
Solid-State Detector and Cherenkov particle telescope that measures very
high energy protons . The instrument relies upon a spin axis nearly
perpendicular to the local magnetic field to provide complete particle
pitch angle coverage once per spin.

**1.4 Observing Modes**

After spacecraft and instrument checkout and calibration, the G-RBSP
will perform a two-year investigation and detailed event analyses of
charged particles, electric and magnetic fields, and plasma waves within
the Earth's inner magnetosphere. Current launch is scheduled for the
early calendar year 2012 timeframe.

**1.5 Reserved**

**1.6 Documents**

**1.6.1 Applicable Documents**

-   2006 NASA Strategic Plan, Doc. No. NP-2006-02-423-HQ. NASA
    Headquarters, Washington, DC, Feb. 2006.

-   Science Plan for NASA's Science Mission Directorate 2007-2016, Doc.
    No. TBD, NASA Headquarters, Washington, DC, March 2007.

-   Living with a Star (LWS) Program Plan, Approved 5-24-05

-   Appendix A to the LWS Program Plan, Level 1 Requirements for the
    Geospace Radiation Belt Storm Probe in the Geospace Mission Project
    dated TBS.

-   Living With a Star Program Commitment Agreement, approved 5/24/05.

1.6.2 Reference Documents

-   [Heliophysics, The New Science of the Sun-Solar System Connection:
    Recommended Roadmap for Science and Technology
    2005-2035]{.underline}, Doc. No. NP-2005-11-740-GSFC. NASA Goddard
    Space Flight Center, Greenbelt, MD, Feb. 2006.

-   *LWS Geospace Storm Investigations, Exploring the Extremes of Space
    Weather* (NASA/TM-2002-211613).

-   Announcement of Opportunity, Radiation Belt Storm Probes
    Investigations and Geospace Related Mission of Opportunity, August
    23, 2005 Doc \# NNH05ZDA003O

-   The RBSP and GR-MOO AO Selection Statement.

**1.7 Background**

[Charged particle energization, transport, and loss are fundamental
processes occurring]{.mark} [throughout the heliosphere, at solar
flares, in the shock waves associated with coronal mass ejections, in
corotation interaction regions, at planetary bow shocks, and in the
termination shock at the outer edge of the heliosphere. However, these
fundamental processes are most readily measurable at the boundaries of,
and within, the Earth's magnetosphere. As is the case for energetic
particle populations throughout the heliosphere, those in the Earth's
magnetosphere form or change in response to varying inputs of solar
energy via coherent interactions, stochastic processes, shock
interactions, wave-particles interactions, and changes in the background
magnetic field configuration. Consequently, knowledge gained from
observing particle energization, transport, and loss within geospace may
be helpful in understanding their variations throughout the heliosphere.
This is an undertaking of considerable societal significance with
particular importance for NASA's Vision for Exploration, which calls for
manned flights to the Moon and Mars.]{.mark}

[The region of space occupied by stably-trapped ions and electrons
depends upon the particle energies. With the exception of the South
Atlantic anomaly, where they can reach the Earth's upper atmosphere,
protons with energies above 10 MeV are confined to a belt at altitudes
below 20,000 km within the vicinity of the geomagnetic equatorial plane.
By contrast, protons with energies below 1 MeV can generally be observed
outward to locations beyond geosynchronous orbit. There are two]{.mark}
[stably-trapped belts]{.mark} [of electrons with energies greater than 1
MeV. The inner belt lies in the vicinity of the equatorial plane at
altitudes below 1 Earth radius (1 R~E~ = 6371 km), whereas the outer
belt lies at altitudes ranging from 2 R~E~ to beyond geosynchronous in
the equatorial plane. Note that the outer belt extends along magnetic
field lines to very low altitudes at high latitudes. The inner belt of
energetic electrons and the belt of high energy (\>10 MeV) protons
overlap and are separated from the outer belt of electrons by a region
known as the 'slot'. By comparison to the inner and outer belts, the
slot generally exhibits depressed fluxes of energetic particles, but can
fill during intense events.]{.mark}

[Energetic electron fluxes in the outer radiation belt can vary by
orders of magnitude on time scales ranging from tens of seconds to
decades in response to convection electric fields, radial diffusion, the
passage of interplanetary shocks, wave-particle scattering and
precipitation into the ionosphere, and the changes in magnetic field
configuration that occur during geomagnetic disturbances and in
association with variations in the strength of the ring current.]{.mark}

[We call abrupt variations in the energetic electron fluxes
"Relativistic Electron Events" or REEs. Such events often, but not
always, correspond to geomagnetic storms. However, particle fluxes can
increase, decrease or remain constant during individual storms. Thus
determining how populations of energetic ions and relativistic electrons
in space form or change in response to changes in solar activity and the
solar wind is a key objective of the G-RBSP mission.]{.mark}

As a stand-alone mission, G-RBSP [addresses NASA strategic objectives
concerning]{.mark} both fundamental science (the processes by which
charged particles are accelerated, magnetospheres respond to solar
variability, and the magnetosphere and ionosphere couple) and hazards to
exploration (extremes, models, and the need to sample the radiation
environment that explorers will encounter). As one in a constellation of
LWS missions, G-RBSP will provide observations essential for end-to-end
research concerning the response of the Earth's magnetosphere to solar
variations. Such studies can also employ observations from a wide range
of other ground- and spaced-based missions, both domestic and
international.

Success in achieving this objective is vitally important for enabling
mission designers to safeguard the journey of exploration by
understanding, specifying, and predicting radiation hazards to
astronauts and spacecraft. Hazards to spacecraft from energetic
particles include the total dose and deep dielectric charging and
discharging. Hazards from lower energy particles include surface
charging, dose, and chemistry. The development of accurate
first-principle and empirical models will prevent costly spacecraft
overdesign and provide critical information for NASA 's Constellation
Programs development of lunar vehicles, missions and outposts

Instrument and measurement requirements for the G-RBSP mission were
derived from the 8 objectives listed in the G-RBSP AO (see Section 2).
These in turn were derived from the work of the Geospace Mission
Definition Team.

**2 G-RBSP Science Objectives and Measurement Needs (Narratives)\
**The section provides an overview of each of the eight G-RBSP Science
Objectives and the needed observations and measurements to fulfill each
objective. Specific measurement requirements are contained in section 4
of this document.

**2.1 AO Objective #1 Differentiate among competing processes affecting
the acceleration and transport of radiation in the form of relativistic
particles.**

Science Basis:

The energization of electrons and ions to relativistic or
near-relativistic energies can be accomplished through a variety of
physical processes that occur throughout the heliosphere and in the
wider universe beyond. In the Earth's radiation belts, energization by
time-varying electric and magnetic fields, wave-particle interactions,
and other processes often occur in overlapping intervals of time and in
a variety of plasma regimes supporting a variety of wave modes. Although
more than one acceleration process may determine the ultimate
distribution functions of radiation belt electrons and ions, each
process has distinct, characteristic, observable signatures that can be
used to identify which process (or processes) have the greatest effect
in individual energetic particle events.

Scope:

**Identifying all discernable local- and transport-associated
relativistic electron and ion acceleration processes and quantifying
when and under what conditions the processes are initiated, sustained,
and/or dominant is the purpose of this objective.** The effects of the
different processes will be determined both individually and
collectively.

The acceleration of electron and ion populations in the Earth's
magnetosphere is facilitated by trapping in the geomagnetic field that
produces long residence times for those particles, enabling multiple
interactions with, or occurrences of, processes that can energize them.
Known energization mechanisms, used to guide RBSP mission planning,
include diffusive acceleration when particles are transported to
stronger magnetic field regions, heating due to plasma waves that have
frequencies comparable to the particle gyrofrequencies, energization and
transport by interactions with waves that have frequencies comparable to
the particle drift frequencies, and direct energization as a result of
electric fields launched by rapid compressions of the magnetosphere.
RBSP will identify the locations, frequencies of occurrences, and
geophysical conditions for each electron and ion acceleration process.
It will identify which parameters determine the amount, timing, and
location of relativistic charged particle acceleration. RBSP will
measure the full range of charged particle distributions and
electromagnetic fields before, during, and after relativistic particle
events to calculate phase space density profiles and track the detailed
evolution of the distribution functions over the event lifetime. RBSP
will also measure the wave fields and wave mode characteristics to
assess the effects of various wave modes on the particle energy spectra
and pitch angle distributions.

The measurements needed to address this objective are:

1.  Electron differential flux (\<=100 eV -- 10's MeV). Continuous
    spectral coverage is required in order to determine PSD at the same
    μ and J at different L-values. Measurements of different pitch
    angles must be such that [continuous pitch angle distributions (from
    0^o^--90^o^ and/or 90^o^--180^o^)]{.mark} can be determined in order
    to evaluate the PSD radial profiles as a function of J. Temporal
    resolution better than one minute and ideally a spin period.

2.  Proton differential flux (500 keV (TBR) to \>50 MeV), Measurements
    of different pitch angles must be such that continuous pitch angle
    distributions (from 0^o^ -- 90^o^ and/or 90^o^ -- 180^o^) can be
    determined. Temporal resolution better than one minute and ideally a
    spin period.

3.  [Plasma distribution functions (less than 50 keV) and bulk densities
    (range/accuracy TBD) and composition must be measured in order to
    determine wave growth rates and conditions that produce
    instabilities.]{.mark}

4.  Quasi-DC magnetic field vectors (magnitude and direction) must be
    measured to calculate pitch angle and μ and to help determine J and
    L\*. Statistical distributions of field measurements must also be
    made to improve storm time global magnetic field models. Magnetic
    field vector measurements are needed to identify impulsive and
    quasi-periodic fluctuations on time scales less than several drift
    periods (10-60 min), and with sufficient time resolution to
    determine characteristics of low frequency wave fields, and
    injection fronts and structures,

5.  3D electric field vectors from DC to 12 Hz to assess the role of
    quasi-static electric fields in energizing particles via radial
    diffusion, substorm injection events and large amplitude
    low-frequency waves. The dynamic range will be 0 to 300 mV/m, with a
    sensitivity of the larger of 10% or 0.3 mV/m for the spin plane
    booms, and the larger of 10% or 2 mV/m for the spin axis booms.

6.  3D E and B wave fields at frequencies 10 Hz to 12 kHz to enable
    identification of wave populations including VLF hiss, whistler
    chorus, small-scale Alfven waves, magnetosonic, electrostatic (e.g.
    ECH), and EMIC waves. Time resolution for full spectra should be at
    least one spin period. Waveform, spectral, and frequency resolution
    must be great enough to enable determination of critical
    characteristics such as wave normal angle (k), phase velocity,
    coherence length, and polarization.

7.  1D electric field to 400 kHz (to determine the upper hybrid line)
    and spacecraft potential measurements from DC to 0.5 Hz for cold
    electron density estimates. Burst waveforms and spectra of density
    fluctuations from the spacecraft potential from DC to 100 Hz.

8.  Two spacecraft measurements in orbits with periods less than
    approximately 9 hrs are required to obtain radial profiles (in the
    same local time sector) separated by times (ΔT) ranging from 10s of
    minutes to ≈4.5 hrs. Two spacecraft measurements enable
    near-simultaneous measurement of source and accelerated particle
    populations. [Two spacecraft measurements separated by times less
    than or comparable to pitch angle diffusion times
    (minute-hour).]{.mark} Full coverage of spatial regions where
    relevant wave fields exist is required.

9.  Spin orientation and rate must optimize pitch angle coverage on time
    scales shorter than 30 sec. Sufficient expendable resources will be
    provided to enable a mission duration of longer than 4 years.

**2.2 AO Objective #2 Differentiate among competing processes affecting
the precipitation and loss of radiation in the form of relativistic
particles.**

Science Basis:

While acceleration of charged particles enhances the fluxes (and phase
space density) of relativistic particles, loss processes act to decrease
flux/phase space density. In the radiation belts, as in a wide variety
of astrophysical systems, the net distribution depends not only on
acceleration processes (objective #1) but also on which loss processes
operate on the distribution, how large an effect they have, where they
occur, and when. The dramatic decrease in relativistic particle fluxes
over much of the Earth's inner magnetosphere at the beginning of many
geomagnetic storms illustrates how rapid and dramatic these loss
processes can be. Processes that result in flux decreases of
relativistic particle fluxes at Earth include reversible adiabatic
effects and real losses through various scattering mechanisms,
magnetopause shadowing, and demagnetization on highly stretched field
lines.

Scope:

**Identifying all discernable relativistic particle loss processes and
quantifying when and under what conditions the processes are initiated,
sustained, and/or dominant is the purpose of this objective**. As with
acceleration (objective #1), each loss process has its own distinct,
characteristic, observable signatures and the effects of the different
processes will be determined both individually and collectively.

Known loss mechanisms, used for mission planning include direct
collisional scattering through interaction with the atmosphere,
scattering that occurs when the gyroradius of particles becomes
comparable to the local radius of field line curvature, losses due to
encounters with the current layer at the magnetopause and with magnetic
field lines that are connected to the interplanetary magnetic field, and
scattering due to interactions with a variety of wave modes including
plasmaspheric hiss, equatorial hiss, electromagnetic ion cyclotron
(EMIC), and chorus. All of these loss processes have a variety of
characteristic time scales, locations and effects. All are viable loss
mechanisms but we do not yet understand which specific mechanism (or
mechanisms) has the largest effect, where they operate and when. To meet
this objective, RBSP will measure the full range of charged particle
distributions and electromagnetic fields before, during, and after
relativistic particle events to track the detailed evolution of the
distribution functions over the event lifetime. RBSP will also measure
the wave fields and detailed properties of each wave mode to determine
diffusion coefficients and assess the scattering effects of various wave
modes on the particle energy spectra and pitch angle distributions.
Models will necessarily be invoked for measurement parameters not
directly accessible to the RBSP spacecraft.

Although low-altitude high-latitude measurements of particles
precipitating into the atmosphere provide the most definitive
quantification of losses caused by mechanisms causing pitch angle
scattering into the atmosphere, the RBSP orbit does not provide those
direct observations in the appropriate locations. The mission
anticipates relying on other measurement sources for this information.

The measurements needed to address this objective are:

1.  Electron differential flux (\<=100 eV -- 10's MeV). Continuous
    spectral coverage is required in order to determine PSD at the same
    μ and J at different L-values. Measurements of different pitch
    angles must be such that [continuous pitch angle distributions (from
    0^o^--90^o^ and/or 90^o^--180^o^)]{.mark} can be determined in order
    to evaluate the PSD radial profiles as a function of J. Temporal
    resolution better than one minute and ideally a spin period.

2.  Proton energy spectra, pitch-angle distributions, and distribution
    functions from 5 keV-400 keV @ 1/spin. Energy resolution of 50% with
    20^o^ pitch angle bins covering 0-180^o^.

3.  Helium, Oxygen energy spectra, pitch-angle distributions, and
    distribution functions from 5 keV-400 keV @ 1/spin. Energy
    resolution of 50% with 20^o^ pitch angle bins covering 0-180^o^.

4.  DC magnetic field vector waveform over the frequency range from DC
    to 15 Hz with a dynamic range from 0 to 32000 nT. Magnetic field
    spectra once per minute over 0.2-32 Hz.

5.  3D low frequency electric field (DC -- \~12 Hz). The dynamic range
    will be 0 to 300 mV/m, with a sensitivity of the larger of 10% or
    0.3 mV/m for the spin plane booms, and the larger of 10% or 2 mV/m
    for the spin axis booms.

6.  3D vector E and B wave measurements from 10 Hz to 12 kHz for chorus,
    EMIC, small-scale Alfven waves, magnetosonic waves, and
    electrostatic waves (including ECH). Spectra, k vector information,
    Poynting flux at spin period cadence. Measure chorus with 30 ms
    resolution.

7.  1D electric field to 400 kHz (to determine the upper hybrid line)
    and spacecraft potential measurements from DC to 0.5 Hz for cold
    electron density estimates. Burst waveforms and spectra of density
    fluctuations from the spacecraft potential from DC to 100 Hz.

8.  Two spacecraft observations are required with a range of local time
    and radial separations from hundreds to thousands of kilometers, and
    spanning a range of hours in local time [(more specificity
    here).]{.mark}

9.  Orbit apogee greater than 5 Re geocentric distance to allow sampling
    of all the important energetic particle populations over a wide
    range of local times.

**2.3 AO Objective #3 Understand the creation and decay of new radiation
belts\
**

Science Basis:

There are at least two classes of processes that create new radiation
belt structures in spatial regions that are fundamentally distinct from
the average, or "expected", configuration. One class is the extremely
large and rapid acceleration produced by interplanetary shocks. The
other class appears to be very large reconfigurations of the inner
magnetosphere that produces energy specific, flux maxima at very low
L-shells where flux minima are more commonly observed (e.g. the nominal
"slot" region). Similar events are seen to produce dramatic increases
(or decreases) in the low-L-shell ion radiation belts which are
otherwise very stable. Still other events produce multiple flux maxima
(as a function of L) that are fundamentally different from the average
or expected configuration. While such events are relatively rare
compared to other relativistic particle events they can produce the
highest energies and/or highest fluxes yet observed in the radiation
belts.

Scope:

**Understanding the conditions that should be expected to produce new
radiation belt structures, and quantifying the basic processes at work
and the mechanisms/time scales over which the structures dissipate is
the purpose of this objective.**

Events that produce transient radiation belt structures that are
fundamentally different than the average conditions are among the most
extreme radiation belt events that have been observed. The most
well-known and well-observed event occurred in March 1991 and was
initiated as an interplanetary shock hit the magnetopause launching a
powerful magnetosonic wave. The shock-produced wave moved through the
magnetosphere transporting relatively low-energy electrons from as far
away as the magnetopause down to L \< 2 and energizing them to energies
greater than 13 MeV. Similar, but less intense shocks are thought to
transport and further accelerate solar energetic particles (SEP) from
regions outside the geomagnetic cutoff to low L-shells where they can
enhance the stably trapped ion belts. Other events such as the
"Halloween" 2003 event produce electron flux peaks (and multiple peaks)
in regions where they are not typically observed. Such extreme events
test our theories and understanding of acceleration, transport, and loss
processes under rare or even unique conditions. Expected applications of
this objective include determination of the magnitude of the effects in
the Earth's inner magnetosphere as a function of species, location,
driver characteristics, and pre-existing conditions.

The measurements needed to address this objective are:

1.  Electrons (0.5 keV --10 MeV), dE/E = 20% below 20 keV, 100% at 10
    MeV, 30s time resolution to 1 MeV, 1 min above 1 MeV, 2D pitch angle
    coverage with pitch angle resolution \< 40°.

2.  Protons 0.1 keV to greater than 10 MeV, dE/E = 20%(TBR) from 0.1 to
    200 keV, 100% at 10 MeV, 1 min time resolution,, 2D pitch angle
    coverage with pitch angle resolution \< 40° at energies below 200
    keV, unknown at higher energies.

3.  Helium, oxygen (0.1 --200 keV), dE/E = 40%(TBR), 1 min time
    resolution, 2D pitch angle coverage with pitch angle resolution
    \<40°.

4.  DC magnetic field (10-40000 nT), 6s resolution, 0.1 nT accuracy at
    4000 nT, 2 nT accuracy at 40000 nT

5.  2-D DC to 12 Hz electric field vector from 0.3 to 300 mV/m, with an
    accuracy of 0.3 mV/m or 10%, whichever is larger

6.  3-D E and B burst mode waveforms from 10 Hz to 12 kHz for chorus,
    EMIC, KAW, and electrostatic waves. , Spectra, wave normal, and
    Poynting flux at spin period cadence.Chorus with 30 ms resolution. ,
    1D electric field to 500 kHz (to determine the upper hybrid line)
    and spacecraft potential measurements for density estimation.

7.  Two spacecraft observations at radial distance separations from 1 to
    several Re.

8.  Perigee less than 1.012 Re geocentric distance (800 km altitude),
    apogee between 5 and 6.6 Re geocentric distance.

**2.4 AO Objective #4 Quantify the relative contribution of adiabatic
and non adiabatic processes on energetic particles.\
**\
Science Basis:

The most important processes affecting energetic particles in the
Earth's radiation belts are those that produce irrevocable changes in
the distribution of those particles. Other processes produce reversible
effects in the energy, pitch angle, or location of energetic particles
which are "adiabatic effects". The effects are reversible in the sense
that, if a processes occurs on scales that are large compared with the
temporal and spatial scales associated with the gyrating, bouncing, and
drifting motions of the particles around, along, and across the magnetic
field lines (conservation of the first, second, and third adiabatic
invariants). then reversing the process will recover the original
distribution of energetic particles. Any process that is slow compared
to a particle drift period will conserve all three adiabatic invariants
and is therefore "fully adiabatic". Processes that conserve one or two
adiabatic invariants are known as "quasi-adiabatic" and only preserve
certain characteristics of the distribution. Although the processes are
reversible, and therefore temporary, they can produce extremely large
changes in the instantaneous distribution at any fixed point in space -
and therefore in the measurements made by satellites. Stretching of the
geomagnetic field changes the distribution of particles on that field
line but also changes which field line is connected to the satellite.
Both changes result in measurements of a different set of particles than
before the change. If the change is sufficiently slow then relaxing the
field back to it's original configuration will result in measurement of
the original distribution of particles. Similarly, slow changes in the
large-scale magnetic field (such as from changes in the ring current)
result in changes in the location of that drift shell, the energy of
particles on that drift shell. In an asymmetric field each pitch angle
is affected differently producing "drift shell splitting". These
adiabatic processes also dramatically change the local distribution of
particles measured by a satellite.

Nonadiabatic processes violate conservation of one or more of the
invariants and therefore result in irreversible changes in the particle
distribution functions -- changes that include acceleration to
relativistic energies and losses that deplete particle populations.
Irreversible acceleration processes include transport-related processes
such as radial diffusion and substorm injection, local acceleration
processes by wave-particle interactions, and others. Irreversible losses
are likewise produced by a variety of nonadiabatic processes such as
curvature-related scattering, wave-particle interactions, magnetopause
shadowing, and others. The detailed physics of the nonadiabatic
acceleration, transport, and loss processes that were identified and
characterized in objectives 1 and 2 must be fully understood -- and
quantified - in relationship to the adiabatic processes discussed above.

Scope:

**The purpose of this objective is to understand in detail how changes
in the local and global electromagnetic fields and plasma distributions
produce adiabatic and nonadiabatic acceleration, transport, and loss of
relativistic particles and to quantify their relative effects.**

RBSP will measure the inner-magnetospheric properties needed to
understand and quantify the conservation and violation of the three
particle adiabatic invariants and the effects on the energetic particle
energy, pitch angle, and spatial distributions. The two RBSP spacecraft
will measure the detailed charged particle distributions and
electromagnetic fields before, during, and after relativistic particle
events and evaluate processes that conserve or violate the first,
second, or third invariants in order to better quantify the effects of
adiabatic and quasi-adiabatic processes on the locally-measured
energetic particle distributions, to better determine the adiabatic
invariants associated with that local population, and thereby understand
the phase space density distribution of the overall energetic particle
populations. For mission planning purposes nonadiabatic processes
include whistler mode acceleration, energization and transport by ULF
waves, acceleration by shocks and injection fronts, energization by
large scale convection electric fields, and acceleration and scattering
by Alfven and ion cyclotron waves. Adiabatic processes include slower
changes in the electric and magnetic fields that produce reversible
motion of particle populations, changes in the local magnetic flux tubes
and their equatorial mapping, and changes in the large-scale magnetic
field that change particle drift shells.

The measurements needed to address this objective are:

1.  Electron energy/pitch angle spectra (0.1 keV --4 MeV), dE/E = TBD
    (30%), accuracy 40%, 12s time resolution, pitch angle coverage
    0-90^o^ or 90-180^o^ with pitch angle resolution 20°. Measure shock
    accelerated electron fluxes up to 10 MeV (20 MeV) goal.

2.  DC magnetic field (20-35000 nT), 1 min resolution, 1 nT or 0.5%
    (which ever is larger) accuracy. Measure direction of magnetic field
    to TBD (0.5) degrees.

3.  2D DC to 12 Hz electric field from 0.3 to 300 mV/m, with an accuracy
    of 0.3 mV/m or 10% (whichever is larger)

4.  Spin axis component for large amplitude signals, from 6 to 300 mV/m,
    with an accuracy of 6 mV/m or 20%, whichever is larger

5.  1-D electric field to 500 kHz (to determine the upper hybrid line)
    and spacecraft potential measurements for density estimates.

6.  Wave magnetic field from 1 Hz to 500 Hz, sensitivity of 0.1 nT for
    amplitudes of 0.1 nT to 10 nT.

7.  3D wave magnetic field from TBD nT to 4 nT, 100 Hz to 10 kHz; 3D
    magnetic field from quasi-static to 10 Hz from 20 - 35000 nT with
    accuracy of 10 nT or 0.5% (whichever is larger)

8.  AC electric fields from 1 Hz to 500 Hz, 1-300 mV/m

9.  Two spacecraft with greater than 1Re separation in geocentric
    distance and less than 8 hours in local time, and multiple passes
    from 2 to 5.5 R~E~ geocentric distances.

10. Geocentric position of perigee less than 2 R~E~, apogee between 5
    and 6.5 R~E~, inclination \<= 18^o^, \>= 10 storms required. Orbital
    period less than 10 hours.

**2.5 AO Objective #5 Understand the role of 'seed' or source
populations for relativistic particle events.**

Science Basis:

When energy is released in a plasma population, some portion of the
background charged particle population is accelerated to very high
energies. These initial populations for relativistic particle events can
be local, could come from outside the immediate region of interest, or
could be the result of step-wise energization from earlier events. The
characteristics of the accelerated population (energy, pitch angle, and
location) depend not only on the physical processes in the acceleration
mechanism but also on the characteristics of the population that is
accelerated. Therefore, understanding or predicting the fluxes, phase
space density distributions, spectral, pitch angle, and other
characteristics of the relativistic particles produced by the
acceleration mechanisms defined in objectives 1 and 3 requires
understanding the same characteristics of the "seed" or source
populations that are accelerated.

Scope:

**Quantifying the potential for various types of pre-existing plasma
populations to be accelerated to relativistic energies is the purpose of
this objective.**

In the Earth's inner magnetosphere, known source/seed populations
include:

-   the plasma sheet (namely, its extension into the inner
    magnetosphere);

-   substorm-injected charged particles;

-   pre-existing, local charged particles;

-   solar energetic particles.

The range of energies that these source particles originally have lead
to a wide range of possible distributions for the subsequently
accelerated particles. RBSP will measure the properties of accessible
source populations, including the energy spectra, pitch angle
distributions, and spatial and temporal distributions as a function of
geophysical conditions including geomagnetic storms, high-speed-streams,
and shocks. The detailed investigations of acceleration mechanisms from
objective #1 and 4 (the initial and final particle pitch angle
distributions as a function of location and geophysical conditions) will
be extended to understand the theoretical limitations of the mechanisms
on the available source populations.

Because direct measurements of the full range of seed and source
populations will not be possible with the RBSP spacecraft, the mission
anticipates supplementing those observations with information from other
measurement sources and/or models.

The measurements needed to address this objective are:

1.  Electrons (0.5 --1000 keV), dE/E \< 40%, 1 min time resolution, 2D
    pitch angle coverage with pitch angle resolution \< 40°.

2.  Protons (0.1 to 400 keV), dE/E \< 40%, 1 min time resolution, 2D
    pitch angle coverage with pitch angle resolution \< 40°.

3.  Helium, oxygen (0.1 --400 keV), dE/E \< 40%, 1 min time resolution,
    2D pitch angle coverage with pitch angle resolution \< 40°

4.  SEPs (5 - \> 500 MeV protons; \> 1 MeV/nuc heavy ions); 3 min
    resolution

5.  DC magnetic field (10-40000 nT), 1 min resolution, 10% accuracy

6.  2-D DC to 12 Hz electric field vector from 0.3 to 300 mV/m, with an
    accuracy of 0.3 mV/m or 10%, whichever is larger

7.  3-D E and B burst mode waveforms from 10 Hz to 12 kHz for chorus,
    EMIC, KAW, and electrostatic waves. Spectra, wave normal, Poynting
    flux at spin period cadence. Chorus with 30 ms resolution.
    Sensitivity/dynamic range TBD. 1-D electric field to 500 kHz (to
    determine the upper hybrid line) and spacecraft potential
    measurements for density estimation)

8.  Two spacecraft passing through same region (string of pearls) close
    in time over a range of separations (minutes to hours); spanning a
    range of radial distances to assure adequate coverage of source
    regions (but not at the expense of minimizing main belt coverage);
    local time coverage of all four quadrants; significant number of
    events coverage.

9.  Sufficient survey and burst mode telemetry; electromagnetically
    quiet spacecraft.

**2.6 AO Objective #6 Understand the effects of the ring current and
other storm phenomena on radiation in the form of relativistic
particles\
**

Science Basis:

The processes that produce changes in relativistic particles in the
inner magnetosphere are intimately coupled (in ways that are not fully
understood) to the larger set of processes that characterize geomagnetic
storms: the transport of energy from the solar wind into the inner
magnetosphere, injection and redistribution of plasma, enhancement of
electromagnetic wave fields, and, in particular, the development and
effects of the storm-time planetary ring current and its interaction
with the thermal plasmas of the plasmasphere.

A planetary ring current is an electric current produced by the
longitudinal drift of energetic, charged particles trapped in a magnetic
field. At Earth, the ring current nominally consists of 10-200 keV ions
and electrons located primarily between L\~2 to 7, which undergo
magnetic gradient-curvature drift that is eastward for electrons and
westward for ions. While the gradient and curvature drifts, along with E
X B drifts are important in distributing the ring current particles, it
is predominantly the gradient in the particle pressure perpendicular to
the magnetic field that results in a westward electric current. Ions,
primarily H+, He+, and O+, contribute far more to the particle pressure
than do electrons,are the dominant producer of the current. Enhanced
particle, and particularly oxygen ion, fluxes reflect increased
contributions from the ionosphere. The ring current produces a magnetic
field component opposite to that of Earth's magnetic field inside the
region encircled by the current, so an observer stationed on the Earth
observes a decrease in the global magnetic field -- the defining feature
of geomagnetic storms. Within the current region itself the magnetic
field is highly depressed, while outside, deeper into the magnetosphere,
the ring current field adds to the Earth's field resulting in distended
field lines. The diamagnetic ring current inflates the geomagnetic field
and introduces unique local time asymmetries. This transient change in
the morphology of the magnetic field affects the trajectories of the
trapped particles producing important adiabatic or quasi-adiabatic
changes in the energetic particle distributions (see objective 4).

The enhancement of the ring current is associated with enhancement of
large-scale convective electric fields and by large- and local-scale
inductive electric fields. Those same fields redistribute plasma
population in the inner magnetosphere including the plasma sheet,
injected populations, and pre-existing local populations (see objective
5). The interaction of the ring current electrons and ions with other
local plasma populations is a source of free energy to excite plasma
waves that in turn scatter or accelerate resident or injected particles.
This energy can also be redistributed amongst the thermal and energetic
particles populations as plasma waves undergo damping. Energy contained
in the ring current can also be transferred to the plasmasphere through
Coulomb collisions.

At lower energies, there is a torus of thermal (\~1 eV), dense (10 to
1000 particles/cc) plasma, called the plasmasphere, that occupies
roughly the same region of the inner magnetosphere as the ring current
and radiation belts (between L=2-7). The plasmasphere is an extension of
the low altitude ionosphere, populated by outflowing ionospheric plasma
along mid- and low-latitude closed magnetic field lines. H^+^ is the
principal component, with minor, activity-dependent, contributions from
He^+,^ O^+^ and other ionospheric-source species. The plasmasphere hosts
plasma wave modes that can remove radiation belt particles by pitch
angle scattering into the loss cone. Other wave modes limited to the
region outside the plasmasphere can resonantly accelerate particles. The
size, shape, and wave dynamics of the plasmasphere and its impact on the
energetic particles vary strongly with the level of geophysical
activity.

Scope:

**The purpose of this objective is to understand how the ring current,
plasmasphere, and other various discernable storm phenomena act to
modify inner magnetospheric magnetic and electric fields and produce
inner magnetospheric waves, and then further, to quantify the potential
these processes have to affect the acceleration and loss mechanisms
identified in RBSP objectives 1, 2, 3, and 4**. RBSP will measure the
composition, energy spectra, pressures, and spatial distribution of the
ring current particles for the purpose of calculating the electric
currents and estimating the associated magnetic field disturbance. The
mission will also measure the properties of the ring current and
plasmasphere particle and wave populations to determine the extent to
which these populations initiate and/or support wave growth processes
and how the intensity and location of these populations vary with
activity level.

The measurements needed to address this objective are:

1.  H, He, O energy/pitch-angle spectra from 5-400 keV. Cadence: 1
    minute. Energy Resolution: 50%. Accuracy: 20%. Interspacecraft
    precision: 20%. Pitch angle resolution: 20 degrees. Pitch angle
    coverage: 0-90 or 90-180 degrees.

2.  Electron energy/pitch-angle spectra from 0.1-4 MeV. Cadence: 12 s; 1
    minute. Energy Resolution: TBD (10%; 30%). Accuracy: 20%; 40%.
    Interspacecraft precision: 10%; 40%. Pitch angle resolution: 10
    degrees; 20 degrees. Pitch angle coverage: 0-90 or 90-180 degrees.

3.  Magnetic field vector. Cadence: 1 minute; 30 Hz. Accuracy: 1 nT

4.  2-D DC to 12 Hz E-vector from 0.3 to 300 mV/m with an accuracy of
    0.3 mV/m or 10%, whichever is larger

5.  3-D burst mode E and B waveforms from 10 Hz to 12 kHz for chorus,
    EMIC, KAW, and electrostatic waves. Spectra, wave normal, Poynting
    flux at spin period cadence. Chorus with 30 ms resolution.
    Sensitivity/dynamic range TBD. 1-D electric field to 500 kHz (to
    determine the upper hybrid line) and spacecraft potential
    measurements for density estimation.

6.  Spacecraft potential measurements for density estimates

7.  Wave data (TBD) specification); 30 msec resolution for chorus

8.  Two spacecraft greater than 1 Re separations between spacecraft and
    less than 8 hours in local time. Geocentric position of apogee
    between 5 and 6.5 Re geocentric and perigee less than 2 Re
    geocentric. Inclination \<= 18 degrees. 10 or more RPE's required

**2.7 AO Objective #7 Understand how and why the ring current and
associated phenomena vary during storms.**

Science Basis:

The ring current and plasmasphere are active elements in the geospace
system in that they respond not only to the changing convection electric
field imposed by solar wind interactions but to internal dynamics of the
magnetosphere-ionosphere-atmosphere system. Variations in the
magnetosphere plasma sheet density, temperature and composition,
saturation of the cross polar cap electric field potential drop,
modifications of the convection pattern due to electric shielding
effects, the presence of pre-existing populations, changes in the
scale-height of heavy ions within the ionosphere, geomagnetic
storm-substorm coupling, and enhanced convection speeds that can occur
with and without accompanying substorm activity all have an impact on
ring current and plasmasphere properties. Understanding how and why the
ring current varies during storms includes understanding processes such
as: the injection of particles into the inner magnetosphere; the motion
of ring current particles through the inner magnetosphere; their
interaction with other plasma populations; the relative distribution and
temporal variation of particles on open and closed drift trajectories
(the so-called partial and symmetric ring current components); and the
gradual decay of the ring current in the recovery phase of storms.

Scope:

**Understanding the mechanisms that control the Earth's ring current and
plasmasphere particle populations, currents, and fields and their
variation through the course of geomagnetic storms is the purpose of
this objective.**

RBSP will measure the intensifications of the global magnetospheric
electric field and the intensifications of the energy density of the
ring current due to particle injections and transport and energization
of plasma sheet particles by the enhanced convection electric field. The
primary loss processes targeted for investigation are charge exchange
with neutral hydrogen atoms in the
[geocorona](http://pluto.space.swri.edu/IMAGE/glossary/geocorona.html),
magnetopause shadowing, and, for lower-energy ring current ions, Coulomb
collisions with the thermal plasma of the
[plasmasphere](http://pluto.space.swri.edu/IMAGE/glossary/plasmasphere.html).
A third process to be investigated is the precipitation of ring current
particles into the atmosphere as a result of wave-particle scattering.

The measurements needed to address this objective are:

1.  H energy/pitch-angle spectra from 5-400 keV. Cadence: 12 s- 60 s.
    Energy Resolution: 10 %. Accuracy: 10 %; 20%; He 40%;20%;.
    Interspacecraft precision: 10 %, pitch angle coverage 0-90 or 90-180
    degrees

2.  He and O energy/pitch-angle spectra from 5-400 keV. Cadence: 12-60s.
    Energy resolution 50%, accuracy 20%, interspacecraft precision: 20%.
    Pitch angle resolution: 20 degrees. Pitch angle coverage: 0-90 or
    90-180 degrees.

3.  H, He, electron density from 0-5 eV. Cadence: 10 minute. Energy
    Resolution: 50%. Density Accuracy: 20%. Interspacecraft precision:
    20%.

4.  Electron energy/pitch-angle spectra from 0.1-4 MeV. Cadence: 1
    minute. Energy Resolution: TBD (30%). Accuracy: 40%. Interspacecraft
    precision: 40%. Pitch angle resolution: 20 degrees. Pitch angle
    coverage: 0-90 or 90-180 degrees.

5.  DC magnetic field vector. Cadence: 0.1 s; 60s. Accuracy: 1 nT.

6.  2-D DC to 12 Hz electric field vector from 0.3 to 300 mV/m with an
    accuracy of 0.3 mV/m or 10%, whichever is larger Spin axis component
    from 6 to 300 mV/m, with an accuracy of 6 mV/m or 20%, whichever is
    larger.

7.  3-D burst mode E and B waveforms from 10 Hz to 12 kHz for chorus,
    EMIC, KAW, and electrostatic waves. Spectra, wave normal, Poynting
    flux at spin period cadence. Chorus with 30 mx resolution.
    Sensitivity/dynamic range TBD.

8.  1-D electric field to 500 kHz (to determine the upper hybrid line)
    and spacecraft potential measurements for density estimation.
    Sensititivity/dynamic range TBD.

9.  Plasma frequency measurement, frequency up to 500 kHz and spacecraft
    potential for density estimates.

10. Two spacecraft greater than 1 Re, geocentric distance separations
    between spacecraft and less than 8 hours in local time.. Geocentric
    position of apogee between 5 and 6.5 Re geocentric and Perigee \< 2
    Re geocentric. Inclination less than or equal to 18 degrees. 10 or
    more RPE's required.

**2.8 AO Objective #8 Develop and validate physics based, data
assimilation, and specification models of the radiation belts for solar
cycle time scales.\
**\
Science Basis:

Current standard models for specifying the Earth's radiation belts, i.e.
AE-8 and AP-8, are limited in spectral coverage, lack quantitative
accuracy, and do not provide a good statistical description of the
dynamic flux distributions characteristic of a solar cycle. An important
application of the science to be pursued with RBSP objectives 1-7 will
be new models that overcome these limitations. The new models are
intended to meet modern spacecraft design requirements and establish
baseline climatologies for nowcast and forecast applications.

Scope:

**The purpose of this objective is the development of physics-based
data-assimilative models of the ring current and radiation belt that can
be run either in a retrospective "re-analysis" mode to establish
long-term (solar cycle) climatology of the space environment, or in a
real-time nowcast/forecast mode to address operational space weather
needs.**

By completing this specific objective, the RBSP mission will serve both
scientific and technological goals. Scientifically, it will provide
physical understanding of the dynamic processes that form and change
populations of relativistic electrons and ions in space, in particular
the trapped particle populations at Earth. Technologically, it will
provide understanding of those aspects of the space environment that
pose hazards to spacecraft, and which must be accounted for when
designing and operating space systems. Based on interactions with the
spacecraft design and operations community, planning for the RBSP
mission has determined that a single focused effort has the potential to
satisfy the needs of both the scientific technological communities.
Physics-based data-assimilative models will be developed of the Earth's
ring current and radiation belts that can be run either in a
retrospective "reanalysis" mode to establish long-term (solar cycle)
climatology of the space environment, or in a real-time nowcast/forecast
mode to address operational space weather needs.

All of the measurements that we need to accomplish the previous science
objectives are essential to fulfilling this science objective. In
addition, this objective levies the following two measurement
requirements:

1.  Protons (a few eV --1 GeV), dE/E = 20% at 1 eV to 100% at 1 GeV[,
    angular resolution 20]{.mark} [degrees]{.mark}, cadence of 1 minute,
    sample rate once per 5 degrees of rotation

2.  Two spacecraft, low inclination orbit, lapping \>4/year, Geocentric
    radius of perigee less than 1.12Re (800 km altitude), apogee 5-6.6
    Re.

**2.9 Science Parameters and Data Archiving**

This section describes the Science Parameters to be developed and
delivered post-commisioning.

**2.9.1 ECT/HOPE**

Proton distribution functions and spectra from 30 eV to 45 keV at spin
period time resolution

He+ distribution functions and spectra from 30 eV to 45 keV at spin
period time resolution

O+ distribution functions and spectra from 30 eV to 45 keV at spin
period time resolution

Electron distribution functions and spectra from 30 eV to 45 keV at spin
period time resolution ECT/MagEIS

Ion pitch angle distributions and spectra from 45 keV to 8 MeV at spin
period time resolution

Electron pitch angle distributions and spectra from 45 to 3000 keV at
spin period time resolution

**2.9.2 ECT/REPT**

Ion pitch angle distributions and spectra from 8 to 75 MeV at spin
period time resolution

Electron pitch angle distributions and spectra from 3 to 10 MeV at spin
period time resolution

**2.9.3 RB-SPICE**

Proton distribution functions, pressure, angular distributions and
spectra from 45keV to 400 keV at spin period time resolution

He+ distribution functions, pressure, angular distributions, and spectra
from 45keV to 400 keV at spin period time resolution

O+ distribution functions, pressure, angular distributions and spectra
from 50keVto 400 keV at spin period time resolution

**2.9.4 RPS (PSBR)**

Proton pitch angle distributions and spectra from 100 MeV to 1 GeV at 1
minute time resolution

**2.9.5 EMFISIS**

DC magnetic field 16 vectors/sec

AC 3-axis magnetic field spectra, 10 Hz to 10 kHz, once each 6s

AC 3-axis electric field spectra, 10 Hz to 10 kHz, once each 6s

AC electric field spectra, 1-axis, 10 Hz to 400 kHz, once each 6s

**2.9.6 EFW**

DC spin plane electric field, 2 components, once each spin

Spacecraft potential, once each spin

2**.9.7 DATA ARCHIVING**

TBS

**3.0 Mission Needs Overview**

This Section provides a brief overview of the derived mission level
needs to meet the science objectives in section 2.0 and provide the
complete set of G-RBSP instrument measurement and data products to
achieve mission success criteria. There are no requirements or shall
statements in this section, all mission level requirements are
incorporated in Section 4 of this document (current form is Excel
spreadsheet)

**3.1 Number of Observatories**

As discussed in section 2.0 the key goals of the G-RBSP Mission are to
distinguish between the transport and local acceleration mechanisms that
underlie the radiation belts. This requires a minimum of two spacecraft
to observe and measure the temporal and spatial variations of the
charged particle properties and the electric and magnetic fields.
Ideally, one spacecraft would reside in a region where energetic
particles are produced or into which energetic particles are transported
while the other follows to see the temporal change in the same region or
at different times resides in the region from which particles are
transported.

To accomplish this, the two observatories would be placed in a low
inclination (near equatorial) elliptical orbit that allows measurement
of both the inner and outer radiation belts each orbital period. As the
separation of the two spacecraft varies during the mission, measurements
of temporal, radial and azimuthally distributions of the charged
particles and electrical and magnetic fields will enable the selection
of the dominant mechanisms and thus the physics operating under
particular conditions.

**3.2 G-RBSP Mission Orbit and Mission Duration**

This section describes the rationale for the primary mission orbit and
mission duration.

**3.2.1 Mission Orbit Constraints**

To effectively measure the radiation belt particles and electric and
magnetic fields that produce and control them the G-RBSP mission orbit
must traverse both the inner and outer radiation belts each orbital
period. This drives the mission orbit to be highly elliptical with a
perigee below the inner belt and apogee that allows the spacecraft to
measure radial cuts through the outer belt.

With respect to inclination the G-RBSP observatories must orbit within
the low latitude radiation belt regions and measure magnetically trapped
particles at or near the magnetic equator. This drives the mission orbit
to low orbital inclinations

As discussed, different acceleration and transport mechanisms control
the radiation belts and these occur at different locations in the
magnetosphere. Hence and it is necessary to provide measurements at the
key radial distances and local times (ie. chorus at dawn, EMIC at dusk,
convection at midnight). Collectively, these constraints drive the
G-RBSP mission orbit to the parameters in table 3.2.1.

Table 3.2.1. Summary table of G-RBSP Mission Orbit

+-----------------+-----------------+-----------------+-----------------+
| G-RBSP Orbit    | Optimal Mission | Acceptable      | Comment         |
|                 | Value           | range           |                 |
+-----------------+-----------------+-----------------+-----------------+
| Inclination     | 10 deg          | 8 -- 18 deg     |                 |
+-----------------+-----------------+-----------------+-----------------+
| Apogee          | 5.8 Re          | 5.3 to 5.8 Re   | Geocentric      |
|                 |                 |                 | distances       |
|                 | 30, 615km       | 26xxx to 30,    | specified       |
|                 |                 | xxx km          |                 |
+-----------------+-----------------+-----------------+-----------------+
| Perigee         | \>600km         | \>600 to \<     | Altitude        |
|                 |                 | 1000km          | specified       |
+-----------------+-----------------+-----------------+-----------------+
| Lapping rate    | 2 times in one  | 4-5 times per   | Small apogee    |
|                 | local time      | year            | difference      |
|                 | quadrant        |                 | (small delta v) |
|                 |                 |                 | needed to       |
|                 |                 |                 | effect lapping  |
|                 |                 |                 | rate            |
+-----------------+-----------------+-----------------+-----------------+

**3.2.2 Mission Duration**

With the orbit attributes in table 3.2.1 the G-RBSP mission requires at
least two years to cover all local times with both spacecraft. Designing
and ensuring two observatories operate concurrently for two years is a
difficult task whilst operating in a radiation environment that can
degrade spacecraft systems.

However, key phenomena controlling the energetic particle distributions
occur at night and in the dawn and evening sectors in local time (ie.
chorus, EMIC,). Thus if both observatories can be launched at the proper
local time (i.e. at or near dawn, then concurrent operations of both
observatories for only a single year is needed to observe the primary
area of scientific interest as both observatories will traverse
approximately 220 degrees local time in that one year period (figure
3.2.2.)

Figure 3.2.2

![](media/image4.jpeg){width="4.241666666666666in"
height="3.3520833333333333in"}

Table 3.2.2.a - Summary of Mission Duration and Mission Design Lifetime
Needs

  ----------------------- ----------------------- -----------------------
  Mission duration        One spacecraft          All timeframes are post
                          operation for at least  commissioning
                          two years, both         
                          spacecraft operate at   
                          least one year          
                          concurrently.           

  Launch window           Within two hours of     To begin operating
                          dawn local time -- TBR) around local midnight
                                                  as soon as possible
                                                  after commissioning
                                                  period.

  Observatory design      2yrs + commission       To ensure each
  lifetime                phases (45days)         observatory can operate
                                                  for at least two years
                                                  in destructive
                                                  radiation environment.
  ----------------------- ----------------------- -----------------------

**3.3 Mission and Observatory Geometry**

It is required that the field of view G-RBSP particle measuring
instruments sweep out a full 360 degree at a regular cadence to
determine pitch angle distributions with respect to the magnetic field.
The greater the spin axis is titled away from a direction perpendicular
to the magnetic field, the more infrequently the particle detectors will
deliver complete pitch angle distributions. Typically the magnetic field
points northward and a sunward pointing spin axis provides full pitch
angle coverage. Hence, the desire to maintain low values for the angle
between the spin axis and the sun-earth axis while in a low inclination
orbit. This leads to a constraint that the observatory spin axis must
not point spin axis off the sun-spacecraft line. Since, many instruments
(ie. particle, electric field) need to rotate a full 360 degrees, the
optimum configuration is for each observatory to be designed as a nearly
sun-pointed spin stabilized spacecraft.

![](media/image5.png){width="2.1381889763779527in"
height="1.8338582677165354in"}

Additionally, the instruments require a spin rate of at least of five
rotations per minute to assure sufficient pitch angle sampling for all
instruments

Since, as discussed in section 1 and 2, key energetic particle events
occur at somewhat unpredictable times there is the need to ensure that
the G-RBSP instruments are in collecting science measurement data as
nearly continuously as possible. However, as the earth orbits about the
sun, the sun-spacecraft spin axis line will process by approximately one
degree per day away from the sun. Periodic adjustments to maintain the
proper pointing constraint for the particle instrument (i.e. less than
20 degrees) and maintain the observatories in a power positive
orientation are therefore required. Additionally it is important to
avoid any maneuvers during major relativistic particle events (RPE's)
which as discussed are key events that need to be captured to meet the
overall scientific objectives of the mission. Therefore there are a
number of mission constraints to maximize science collection time and
ensure capture of infrequent RPE's events. Foremost is on-board storage
and holding of at least 5-6 days of science measurement data to ensure
proper transmission from the observatories ground receipt of these
events that average 3-5 days in length.

**3.4 Mission Data and Timing Needs**

The success of the G-RBSP mission depends upon the return of sufficient
science instrument data to accomplish the mission objectives. Overall,
the five G-RBSP instruments require an aggregate average daily data
volume of TBD Gbits per day per day to ensure the required science
parameters and analytical studies and investigations can be conducted.

Timing knowledge between events on both spacecraft are driven by the
need to know temporal differences between the two spacecraft measured
events to within 100msec to properly sample kinetic waves structures
which can prorogate at velocities of 1000km/sec.

As discussed in the science objectives section a coordinated burst mode
is required on each observatory to trigger a higher fidelity, high rate
data collection from some instruments for short durations (\< 5 to 10
minutes).

Data from both observatories are to be downlinked daily to multiple
ground stations that are linked electronically to the centralized
Mission Operations Center. To ensure that key data is not corrupted or
lost, especially significant radiation events, an overall maximum
latency of 72 hours from completion of downlink of data to first level
analysis of the data by the science operations centers is required.

Post processing relative observatory position of 10km or less is
required for science data product generation with post ground processing
attitude knowledge of less than one degree required.

**3.5 External interfaces**

For meeting the requirements in this document the G-RBSP project is
dependent on contractually obtaining a launch vehicle and launch vehicle
services from the KSC EELV Program and obtaining communication and
tracking services from the Space Communications Program both of which
are managed under the Space Operations Mission Directorate (SOMD).
Separate bilateral interface control documents will be negotiated and
agreed to by the G-RBSP Project with each of these programs.

**Section 4.0 G-RBSP Level 2 Science and Mission Requirements**

Current section is incorporated in a excel spreadsheet, after sufficient
maturity the requirements in this section will be incorporated in text
version into this section.

(see separate spreadsheet)

Appendix A. Abbreviations and Acronyms

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  **Abbreviation/   **DEFINITION**
  Acronym**         

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    

                    
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