Discussion of Synoptic Program and Use of SSR2

021104-06SECCHI_CDR_HW_Overview.1

Discussion of Synoptic Program and Use of SSR2

SECCHI Consortium

SECCHI Consortium meeting

7 March 2007

Univ. Paris XI


Observational Programs

• Mission Design Parameters:

– Constantly increasing separation angle: 22º /yr each spacecraft

– Telemetry (DSN) limited, decreasing over course of mission, minimal real-time commanding, generally weekly observing plans

– Simultaneous identical observations from both spacecraft

• Two telemetry buffers used simultaneously: SSR1/Synoptic and SSR2/Special Event Buffer:

- Synoptic: uninterrupted observing program

- Identical programs always maintained in both spacecraft

- Permits stereoscopic observations: EUVI early mission, coronagraphs later mission

- Based in part on evolving separation and data rate

- Event: circular buffer filled at high rate, frozen/read after event

• Special Observing Programs:

– Two, three week ~double telemetry periods early in mission especially useful for EUVI

– Special observations from On-Board CME detection capability


Science


SECCHI Instrument SuiteSystem Description

Dan Moses

SECCHI Program Scientist

Naval Research Laboratory/Praxis, Inc.

(202) 404-8108

[email protected]


SECCHI Instrument Requirements

• The SECCHI Instrument Requirements Are Obtained From:

1) The STEREO Science Requirements (STEREO Mission Requirements Document 460-RQMT-0001)

2) The SECCHI Science Goals (SECCHI Science Requirements & Instrument Performance Specification Document 7906-SPC-9-0-003)

• The Flow Down of STEREO Requirements and the Derivation of the SECCHI Requirements Are Detailed in the SECCHI Science Requirements & Instrument Performance Specification Document


STEREO Level 1 Science Objectives

• Understand the Causes and Mechanisms of CME Initiation

• Characterize the Propagation of CMEs Through the Heliosphere

• Discover the Mechanisms and Sites of Energetic Particle Acceleration

• Develop a Three-Dimensional, Time-Dependent Model of the Magnetic Topology, Density, and Velocity Structure of the Ambient Solar Wind

SECCHI Requirements Flow Down


Mission Science Measurement Requirements SECCHI Instrument Requirements Flow Down

1A Determine the CME Initiation Time to an Accuracy of Order 10 Minutes

1B Determine the Location of the CME Initiation to Within ±5 Degrees of Solar Latitude and Longitude

2C Determine the Evolution of the CME Mass Distribution and the Longitudinal Extent to an Accuracy of ±5 Degrees As It Propagates in the Low Corona, the Upper Corona and the Interplanetary Medium

2D Determine the CME and MHD Shock Speeds Accurate to ±10% As It Propagates in the Low Corona, the Upper Corona and the Interplanetary Medium

2E Determine the Direction of the CME and MHD Shock Propagation to Within ±5 Degrees of Latitude and Longitude As the CME Evolves in the Low Corona, the Upper Corona and the Interplanetary Medium

4J Obtain a Time Series of the Solar Wind Speed Accurate to ±10% at Two Points Separated in Solar Longitude


SECCHI Science Measurement Goals

1A Determine the CME Initiation Time to an Accuracy of Order 1 Minute

1B Determine the Evolution of the CMEs, the Transition Region Structures, the Coronal Structures, EUV Waves, Coronal Dimming and Global Interactions at the Highest Cadence Rate and Matching Positional Accuracy

2A Determine the Three-Dimensional Evolution of CMEs and Associated Disturbances in Ambient Structures in the Lower Corona, the Upper Corona, and in the Interplanetary Medium at the Highest Cadence Rate and Matching Positional Accuracy

2B Determine the Evolution of the Tracers of CME Interaction With the Corona and Interplanetary Medium, the CME Shock Formation, and the Ambient Material Sweep-up at the Highest Cadence Rate and Matching Positional Accuracy

3A Determine the Candidate Sites of Energetic Particle Acceleration With a Timing Accuracy of ≤ 1 Minute

3B Determine the Evolution of the CME Front at the Highest Cadence Rate and Matching Positional Accuracy

4A Determine the Three-Dimensional Shape of Coronal Loops, Coronal Streamers, and Large-Scale Coronal Structures and Solar Wind Tracers With a Positional Accuracy of ≤1250 km in the Lower Corona From the Solar Disk to 1.5 Rsun, ≤4500 km in the Lower Corona From 1.5 Rsun to 3.0 Rsun, and ≤ 11,500 km in the Upper Corona


Image Positional Accuracy Requirements Based on Velocity Accuracyand Number of Images for CME / Solar Wind Evolution Analysis


SECCHI Observation Requirement Set Metric Relationship to theDerived Quantities in the STEREO Measurement Requirements


SECCHI Observation Requirement Subset for EUV Emission and Visible Light Images


SECCHI Observation Requirement Subset for 3D Images


Image Cadence Goals to Capture CME Evolution Over Individual Coverage Regions


Discussion of Synoptic Program and Use of SSR2

SECCHI Consortium

SECCHI Consortium meeting

7 March 2007

Univ. Paris XI


STEREO Level 1 Science Objectives

• Understand the Causes and Mechanisms of CME Initiation

• Characterize the Propagation of CMEs Through the Heliosphere

• Discover the Mechanisms and Sites of Energetic Particle Acceleration

• Develop a Three-Dimensional, Time-Dependent Model of the Magnetic Topology, Density, and Velocity Structure of the Ambient Solar Wind

SECCHI Requirements Flow Down


After viewing the first SECCHI Images,how to achieve these objectives?

•Well observe a subset of events

• Catch every event


Science: Example from NRL Discussion

• 3D studies – Stereoscopy

– Requires “feature/tie-point” identification and minimization of error in height (Z) determination based upon knowledge of X-Y coordinates

– Requires detailed timing knowledge

– Optimal angles are between 3º < α < 15º, first 6 months of mission

• Timing of CME related structures: one spacecraft sees limb events along with coronagraph while second spacecraft sees disk event + halo coronagraph event

– Best suited for ~90º separation or ~ 2 years into mission

• Science emphasis shifts as separation angle between observatories increase, can not repeat observations: requires careful planning, i.e. similar to interplanetary mission

• Desire to design a mission long synoptic program that best balances the many scientific studies that can/should be performed with EUVI


SECCHI/EUVI Science Objectives

Science Goal Brief Description

Note, many science objectives overlap and do not clearly fall into a single label.

Reference, DEM • Provide calibrated reference image and track long term coronal structure changes

CME Propagation • Determination of the three-dimensional properties of the CME and related structures in the low corona – structure, acceleration - both morphology and temperature

• Response of the low corona – both morphology and temperature

Loop Reconstruction &

CME Precursors

• Determination of the three-dimensional coronal structure of pre/post CME active regions

• Determination of the coronal temperature structure

• Stereoscopy (“tie-point”) effective only early mission

CME Initiation • Determination of the relative timing between CME related structures (cavities, dimmings, waves, brightenings, flares) involved in CME initiation

• Physical relationship of CME related structures, e.g. dimming regions and CME material – morphology, temperature through DEM

• Large angular separations best for combining two S/C observations

• High time cadence early in the mission for using single S/C

The EUVI plays a critical role in addressing the STEREO/SECCHI science objectives, in particular:


Proposed Image Schedule: SSR1, SSR2 default

• Exposure times (seconds) weighted toward achieving S/N

– 171 = 4s, 195 = 6-8s, 284 = 30s, 304 = 6-8s

• Compression factors based upon initial image sets

• No Image binning

• SECCHI SSR1 allocation ~4700 Mbit/day, desire EUVI have ~40%

Science Goal Passband Cadence S/N (EXPTIME issue)

Compression Telemetry usage (Mbits/day)

Reference, DEM 171,195,284,304 1/day >5 in coronal holes

Rice (~2.5) 111

CME Propagation

171+284

195+304

10 minute cadence, each pair, separated by 5 min

>3-5 @ 1.5Rsun

ICER5 (30x)

ICER4 (20x)

747

992

Loop Reconstruction &

CME Precursors

Goals are achieved by combination of above images

CME Initiation/ SSR2 backbone program

195+304 2.5 minute >3 in prominence or CH

ICER4 2978 over multiple days


Special Programs (non-synoptic)

• SSR2 = Circular/Event buffer, 4-8 hours of data: Variety of Options

1. Polar plume studies, deep exposures, all 4 passbands, synchronized on A,B

2. Alternating wavelength per spacecraft

a. 3 passbands (171A, 195A, 284A) – 30 sec, higher compression

b. 3 passbands (284A, 171A, 195A) – 30 sec, higher compression

• Special 3 week “double” telemetry observing periods (x2), Options:

– 10 second cadences single line (10 minute test just performed)

– Flare studies

– 1 minute cadences 4 lines

– Etc…

Documents

Discussion of Synoptic Program and Use of SSR2