![](media/image1.png){width="1.4484251968503936in"
height="1.2807086614173229in"}

> **POST -- RB-SPICE WEEKLY MEETING** **3-19-07**
>
> **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:

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. Distinguishing between energetic charged particle
source and loss regions, determining their spatial extents, and
discriminating between proposed interaction mechanisms 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. 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.

To achieve these objectives, instruments on the G-RBSP spacecraft must
make charged particle observations, including composition, 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). 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 particles within the radiation belts 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 (10
Hz to 10 kHz). 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.

The measurement requirements for the G-RBSP mission will be met by
combining observations made by the following investigations:

1.  The Energetic Particle, Composition and Thermal Plasma Suite. This
    investigation was selected to determine the physical processes that
    produce radiation belt enhancements, determine the dominant
    mechanisms for relativistic electron loss, determine how the inner
    magnetospheric plasma environment controls radiation belt
    acceleration and loss, and develop empirical and physical models for
    understanding/predicting radiation belt space weather effects.

2.  The Electric and Magnetic Field Instrument Suite and Integrated
    Science (EMFISIS) on Radiation Belt Storm Probes. By focusing on the
    important role played by DC magnetic fields and plasma waves (10 Hz
    to 10 kHz) in radiation belt particle acceleration and loss, this
    investigation provides the information needed to understand all
    magnetospheric plasma waves relevant to the radiation belts and the
    evolution of the magnetic field that controls the structure of the
    radiation belts and the storm-time ring current. EMFISIS
    measurements of high frequency waves will provide a measure of the
    ambient plasma density.

3.  Electric Field and Waves (EFW) Instrument. The investigation was
    selected to provide understanding of the DC electric fields
    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). This investigation was selected to accurately measure
    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 radiatio
    particle populations. ( presently set to exact wording of HQ to GSFC
    letter)

5.  The Relativistic Proton Spectrometer (RPS). This investigation will
    measure and provide specification models of the high-energy protons
    that populate the inner Van Allen radiation belt.

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 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 science 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 flight investigations Announcement of
> Opportunity, 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

> In addition, the National Reconnaissance Office is providing an
> investigation through a partnering agreement with NASA:

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 analyzer
and time of flight mass spectrometer that measures low energy 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
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 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 varying
magnetic field The WAVES is a triaxial search coil magnetometer and a
set of waveform receivers that measures the 3 components of the magnetic
field and the 3 components of the electric field over higher frequencies
ranging.

The EFW investigation will supply an instrument comprised of three
electric field sensor pairs on three paired 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 RB-SPICE investigation will supply a time-of-flight instrument that
measures and discriminates between H, He,and O 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 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 survey 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 Term Definitions**

**Requirements** are those mission and instrument capabilities that are
needed to achieve the stated science goals, and represent objectives to
be met in the design of the instruments and spacecraft. All requirements
use the verb \"shall\". All requirements are incorporated in section 4
of this document

**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 Start (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 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.

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
stably-trapped belts 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.

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.

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.

Success in achieving this objective will have several important
benefits. First, it will enable 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 anddeep dielectric
charging and discharging. Hazards from lower energy particles include
single event upsets and surface charging. The development of accurate
first-principle and empirical models will prevent costly spacecraft over
design and provide critical information for the Crew Exploration Vehicle
and transits to the Moon.

As a stand-alone mission, G-RBSP addresses NASA strategic objectives
concerning both fundamental science (the processes by which charged
particles are accelerated, magnetospheres respond to solar variability,
and the magnetosphere-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.

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.**

The radiation belt structure and variability arise from the competition
of acceleration and loss. Objective 1 focuses on identifying what
processes contribute to the acceleration and transport of radiation belt
particles, when and where those processes participate, and which
processes are most important at different times and places. The specific
tasks are: 1) Determine the importance and effects of local acceleration
processes as distinct from the acceleration that accompanies particle
transport from one region to another. 2) Determine the particle
energization due to transport from the source region to the radiation
belt regions. Transport mechanisms include: convective transport and
\"radial\" diffusion typically associated with random or quasi-periodic
changes in the electric and magnetic fields in the inner magnetosphere.
3) Determine how one particularly important periodic change, Ultra Low
Frequency waves, transports and accelerates radiation belt electrons and
ions. 4) Determine the frequency, characteristics, and effects of
acceleration associated with interplanetary shocks that impact the
magnetosphere. 5) Investigate whether specific local acceleration or
transport processes (such as Alfvén waves, electrostatic structures,
etc.) have important effects on radiation belt structure and dynamics.
6) Quantify the effects of transport that preserves the so-called
particle adiabatic invariants of gyration and bounce on radiation belt
particles in order to determine the effects of other acceleration and
transport processes that do not preserve the invariants. More details
about this objective are found in Appendix A.

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^) 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 (100 eV to \>10 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 (energy range TBD) and bulk densities
    (range/accuracy TBD) must be measured in order to determine wave
    growth rates and conditions that produce instabilities. Plasma
    distribution functions should also be used to determine convection
    velocities.

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 ULF wave fields, and injection fronts
    and structures,

5.  2-D electric field vectors from DC to 12 Hz as described for
    magnetic field vectors above (#4)

6.  3D E and B wave fields at frequencies 10 Hz to 12 kHz
    (sensitivity/dynamic range TBD) to enable identification of wave
    populations including VLF Hiss, whistler chorus, KAW, electrostatic,
    and EMIC waves. Time resolution for full spectra must be as high as
    practical and no greater than one spin. Waveform, spectral, and
    frequency resolution must be great enough to enable determination of
    critical characteristics such as wave normal angle (k). The wave
    field measurements should enable determination of whether
    interplanetary shocks produce or alter other wave populations in the
    inner magnetosphere.

7.  1D electric field to 500 kHz (to determine the upper hybrid line)
    and spacecraft potential measurements for density estimates.

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
    minutes to ≈4.5 hrs. Two spacecraft measurements that enable
    near-simultaneous measurement of source and accelerated ring current
    populations. Two spacecraft measurements of the same region of space
    (local time and L\*) separated by times less than or comparable to
    pitch angle diffusion times (minute-hour). Full coverage of spatial
    regions where relevant wave fields are found.

9.  Spin orientation and rate must enable full pitch angle measurements
    on time scales shorter than 30 sec. Sufficient expendable resources
    to enable mission durations longer than 2 years.

More information concerning the methodology needed to achieve this
objective can be found in Appendix A.

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

The radiation belt structure and variability arises from the competition
of acceleration and loss. Objective 2 focuses on identifying what
processes contribute to the loss of radiation belt particles, when and
where those processes participate, and which processes are most
important at different times and places. The specific tasks are: 1)
Determine the importance and variability of loss rates caused by
particle angle scattering that arises from particle interactions with
waves that propagate within the magnetosphere. 2) Determine the
importance and variability of loss rates caused by particle angle
scattering that arises from particle interactions with the narrow
current sheet that resides at the base of the magnetic tail of the
magnetosphere. 3) Determine the importance and variability of loss rates
caused by particle interactions with the outer boundary of the
magnetosphere, the magnetopause. 4) Determine the importance and
variability of loss rates that arise from angle scattering that occurs
when particles Coulomb-scatter with other constituents of the
magnetosphere. 5) Determine how all of these processes act together, and
their relative importances, by constructing multi-process
precipitation/loss models.

The measurements needed to address this objective are:

1.  Electron energy/pitch-angle spectra from 0.1-4 MeV at 1/spin, with
    an energy resolution of TBD (30%) with 20^o^ pitch angle bins
    covering 0-180^o^. Electron distributions (10 eV-30 keV) at XX
    ms/sweep. Energy resolution of 20% with 20^o^ pitch angle coverage
    from 0-180^o^. Plasma measurements of electrons over 10 eV-1 keV for
    computation of bulk density.

2.  Protons energy/pitch-angle spectra 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/pitch-angle spectra 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 at 32 vectors/s over the range 0.1-4000 nT.
    Magnetic field spectra once per minute over 0.2-32 Hz.

5.  2D (perpendicular to B) low frequency electric field (DC - 10Hz).

6.  3D vector E and B waveforms from 10 Hz to 12 kHz for chorus, EMIC,
    KAW, and electrostatic waves. (Sensitivity/dynamic range TBD)
    Spectra, wave normal, 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 estimates.

7.  Two spacecraft observations are required with a variety of local
    time and radial separations.

8.  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.

More information concerning the methodology needed to achieve this
objective can be found in Appendix A.

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

Under certain conditions a new radiation belt can suddenly appear within
the previously empty slot region separating the pre-existing inner and
outer radiation belts. This objective focuses on identifying and
quantifying the processes that lead to the abrupt appearance and gradual
decay of this new radiation belt. Amongst these processes are the
interaction of the interplanetary shocks with the magnetosphere and
geomagnetic storms. Strong interplanetary shocks strike the
magnetosphere then transport and further energize radiation belt
particles. Weaker shocks can transport and further energize SEP
particles. During geomagnetic storms, strong electric fields can
introduce radiation belt electrons into the slot region. Expected
results include a determination of the magnitude of the mechanisms that
generate and dissipate the new belts 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.

More information concerning the methodology needed to achieve this
objective can be found in Appendix A.

**2.4 AO Objective #4 Quantify the relative contribution of adiabatic
and non adiabatic processes on energetic particles.\
**\
A key goal of the RBSP mission is to quantify the relative contributions
of adiabatic versus non-adiabatic processes on energetic particles. The
phase space distributions of these particles are controlled by the
violation or conservation of the adiabatic invariants, the foci of this
objective. Phenomena associated with the conservation or violation of
the three adiabatic invariants and their effect on the energetic
particle phase space distributions include: whistler acceleration of
electrons, ULF energization and transport of electrons and ions,
acceleration by injection fronts, large scale convection electric field
acceleration, particle scattering by Alfven and ion cyclotron waves, and
adiabatic acceleration/deceleration by diamagnetism of the ring current
(the Dst effect). To quantify the relative importance of the different
adiabaticity processes the RBSP mission will combine measurements and
modeling of all combinations of the conservation and violation of the
three invariants.

The measurements needed to address this objective are:

1.  Electron energy/pitch angle spectra (0.1 --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.

More information concerning the methodology needed to achieve this
objective can be found in Appendix A.

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

Understanding the acceleration of radiation belt electrons and ions, and
particularly, predicting their effects, implies a fundamental need to
identify and characterize 'seed' or source populations. This fifth
objective will identify these sources and determine how variations in
these sources affect the relativistic particle populations.

To accomplish this objective, the RBSP mission will measure the
locations and characteristics of the source populations having direct
impacts on the relativistic particle events and determine the conditions
that lead to their variability. This objective includes: how transport
to the radiation belts and energization occurs, the effects of shocks or
discontinuities propagating through the inner magnetosphere, and the
generation of waves by unstable plasma distributions that in turn
interact with the energetic particle populations.

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.

More information concerning the methodology needed to achieve this
objective can be found in Appendix A.

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

Understanding the dynamics of the radiation belts depends on
characterizing the ring current, its dynamics, and its modification of
the global magnetic and electric field. The goal of this objective is to
understand the reasons why the ring current particle populations,
currents and fields vary through the course of geomagnetic disturbances.
The diamagnetic effects associated with the ring current sets the
magnetic coordinate system that specifies the structure of the radiation
belts and the plasma motions. Changes in these currents associated with
the onset of geomagnetic disturbances produce major decreases in
electron fluxes and increases during the recovery phase. Further, the
ring current ions provide the free energy for the plasma wave growth
that contributes to electron acceleration, transport and loss. The
challenge is to understand these effects when the ring current processes
operate simultaneously with other acceleration, transport and loss
mechanisms.

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

More information concerning the methodology needed to achieve this
objective can be found in Appendix A.

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

In order to satisfy Objective #6 while developing a predictive
capability for the effects of the ring current on the radiation belts,
it is necessary to understand the reasons why ring current particle
populations, currents and fields vary through the course of geomagnetic
disturbances. This objective requires a determination of the ring
current ion injection and energization processes and its global
dynamics. The ring current time history is needed to differentiate among
the competing loss processes and its dependence on solar conditions, and
must include the effects of plasma waves and the magnetopause on the
particle distributions.

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.

More information concerning the methodology needed to achieve this
objective can be found in Appendix A.

**2.8 AO Objective #8 Develop and validate physics based, data
assimilation, and specification models of the radiation belts for solar
cycle time scales.\
**\
Current specification models for the radiation belts are limited in
spectral coverage, lack quantitative accuracy and do not provide a
statistical description of the dynamic flux distributions characteristic
of a solar cycle. The purpose of this objective is to overcome these
limitations by developing (1) empirical models describing ion and
electron populations as a function of solar wind and geomagnetic
conditions and (2) first-principle models describing ion and electron
dynamics within the inner magnetosphere throughout the solar cycle. When
appropriate for long-term reanalysis and now casting, data assimilative
techniques will be applied to the physics-based models. When possible,
the reanalysis will be extended over the entire solar cycle.

The measurements required for this objective include:

1.  Electrons (1 eV --10 MeV), dE/E = 20% at 1 eV to 100% at 1 GeV,

2.  Protons (1 eV --1 GeV), dE/E = 20% at 1 eV to 100% at 1 GeV, angular
    resolution 20 degrees, cadence of 1 minute, sample rate once per 5
    degrees of rotation

3.  Helium -- TBD -- 45keV -- 400keV; dE/E 40%

4.  Oxygen (10 eV --400 keV), dE/E = 20% at 1 eV to 100% at 1 GeV

5.  Magnetic field vector once per spin or more (TBD), directional
    accuracy \< 2°. Sensitivity 0.05 nT, absolute accuracy 10 nT, range
    1 to 40000 nT

6.  DC to 12 Hz Electric field, accuracy larger of 0.3 mV/m or 10%,
    range 0.3 to 300 mV/m. Spin axis component must measure 6 to 300
    mV/m with an accuracy of larger of 6 mV/m or 20%.

7.  3-D waveform burst electric field from 10 Hz to 12 kHz.

8.  Spacecraft potential measurements for density estimates

9.  3-D wave magnetic field at frequencies from 10 Hz to 10 kHz

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

More information about the methodology required to achieve this goal can
be found in Appendix A.

**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, xxxkm       | 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 rate
ranging between TBD kbps daily and daily data volumes of approximately
TBDGbps per day to ensure the required science parameters and analytical
studies 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 (50 msec accuracy per spacecraft) 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 at JHU/APL. To ensure that key data is not
corrupted or lost, especially key RPE events, an overall maximum latency
of 72 hours from observation to receipt at the MOC and SOC, including
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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