Mission Requirements Document (MRD) Hierarchy

Science Requirements

Spacecraft Requirements

1.1

Science Observations

4.1

Structural /Thermal

1.2

Data Capture & Completeness

4.1.1

Launch Vehicle Accommodation

1.3

Angular Resolution & Coverage

4.1.2

S/C & Instr Accom.

1.5

Precision, Acc, & Dyn Range

4.1.3

Thermal Monitoring and Control

1.6

Cadence

4.1.4

Instrument Optical Bench

4.2

Attitude Control & Determination

Mission Implementation

4.2.1

Acquisition

2.1

Orbit

4.2.2

Pointing Knowledge

2.2

Mission Life

4.2.3

Attitude Control and Stability

2.3

Environment

4.2.4

Propulsion & Delta-V

2.4

Launch Vehicle (LV)

4.2.5

Momentum Management

2.5

Mission Implem/ Ops Concept

4.2.6

Safehold

2.6

Standard Spacecraft Services

4.3

Power

2.7

Development Approach

4.3.1

Power Generation

4.3.2

Power Storage

Instrument Requirements

4.3.3

Power Distribution

3.1

EVE

4.3.4

Load Shedding

3.1.1

Alignment, Jitter & Stability

4.3.5

Constraints

3.1.2

Spectral Resolution

4.4

Comm & Data System

3.1.3

Timing

4.4.1

S-Band Communications

3.1.4

Data Completeness

4.4.2

Ka-Band Communications

3.1.5

Interface Requirements

4.4.3

Data System Functions

3.2

HMI

4.5

HGA Assembly

3.2.1

Alignment & Jitter

4.5.1

Operation, Pointing and Stability

3.2.2

Angular Resolution

4.6

Deploy Actuation and Verif

3.2.3

Timing

4.6.1

Solar Array Deploy and Verif

3.2.4

Data Completeness

4.6.2

HGA Deployment and Verification

3.2.5

Interface Requirements

3.3

AIA

Ground Segment Requirements

3.3.1

Alignment & Jitter

5.1

Integration and Test (I&T)

3.3.2

Angular Resolution

5.1.1

High Rate Science GSE

3.3.3

Timing

5.1.2

Low Rate GSE

3.3.4

Data Completeness

5.2

Ground Station Implementation

3.3.5

Interface Requirements

5.2.1

Dedicated Site Requirements

3.3.6

Dynamic Range

5.2.2

Ancillary Site Requirements

5.2.3

Commanding

5.2.4

Housekeeping Telemetry

5.2.5

Tracking

5.2.6

Science Telemetry

5.3

Mission Operations Center (MOC)

5.3.1

Cmd and Tlm Functions

5.3.2

Data Products

5.4

Science Operations Center (SOC)

5.4.1

Ops

5.4.2

Archive

5.4.3

Data Products

5.4.4

Science Data Acceptance

APS- Antenna Pointing System

INSTR- Instruments (EVE, HMI, AIA)

C&DH- Command & Data Handling Subsystem

LV- Launch Vehicle

CONTAM- Contamination Subsystem

MATL - Materials and Process Subsystem

DEPLOY- Deployment Subsystem

MECH- Mechanical Subsystem

ELEC- Electrical Systems

PARTS- Parts Subsystem

FLT DYN- Flight Dynamics Subsystem

PROP- Propulsion Subsystem

FSW- Flight Software Subsystem

PWR- Power Subsystem

GN&C- Guidance, Navigation and Control Subsystem

RAD- Radiation Effects Subsystem

GND- Ground Segment

RF- RF Communications Subsystem

GSE- Ground Support Equipment Subsystem

THERM- Thermal Subsystem

Observatory = Combination of Spacecraft flight segment and Instrument flight segments

Instruments = EVE, HMI, & AIA Flight segments

SOC = Science Operations Center

Ground System = Command and control facility and equipment located in the Mission Operations Center (MOC)

Ground Station = Remotely located antenna site and data distribution facility

Ground Segment = All ground elements, including ground system, Instrument SOCs, SDO ground station, and any ancillary ground stations

CCR# & Date

Title

Functional Requirement

Performance Requirement

Rationale

Comments

Subsystem Allocation

Trace From

Verify Method

Verf. Lead

Verf. Status

Verf. Data Ref.

Sig Appr

Science Requirements

1.1

Science Observations

The science mission shall perform solar observations sufficient to characterize solar activity as the sun exits from a period of solar minimum and progresses to a period of solar maximum

N/A

1.1.1

The SDO Observatory will launch during or shortly after solar minimum (June 2007 to August 2008) in order to permit observations as the solar cycle progresses towards solar maximum

Defines launch requirement within a range that allows initial observations at end of solar minimum.

This requirement may be removed upon later review (BJT)

Project

SDO Program Level Reqs (PLRs), Location TBD

1.1.2

Science observations shall cover 5 years of the progression from solar minimum to solar maximum to meet full mission success science requirements

Addresses mission life in conjunction with desired observation phase

This requirement will probably be revised further to reflect that observations must be performed over a significant fraction of the prime mission (probably 80%). Minimum success will be achieved with science observations performed over 40% of the prime mission.

ALL

SDO Program Level Reqs (PLRs), Section A-2.1.1.1 and A-2.1.1.2

1.2

Data Capture & Completeness

The end-to-end system of the SDO Instrument, Spacecraft, and Ground System shall obtain and deliver solar observations to the Investigator’s SOCs of sufficient quality to achieve the mission science objectives.

N/A

1.2.1

The end-to-end HMI Data Capture budget requires 22 72-day periods, with each 72-day period capturing 95% of all possible science observations in order to be complete, including delivery of these data to the SOCs. The EVE and AIA data capture budgets require 90% of all possible science data over the 5 year mission life period. "All possible science" is defined as all science observations that could be collected over the mission life assuming no viewing interruptions or data losses.

Defines instrument data capture budget driving various facets of SDO mission system design

Refer to the SDO Data Capture Budget (464-SYS-SPEC-0010) for the collection of the data losses covered in the 95% data capture budget. For minimum mission success, the Observatory shall return 80% of AIA and EVE data, while a minimum mission of 11 72-day periods is specified in the HMI Science Observation Requirements table in the Level 1 Science Requirements Document. Note that HMI is the driver of this requirement as well as the completeness requirement.

INSTR, C&DH, GN&C, APS, RF, GND

SDO Program Level Reqs (PLRs), Section A-2.1.2.2

1.2.2

SDO-CCR-064 & 3/2/04

For the purpose of 1.2.1 an HMI observation shall be considered complete if it is at least 99.99% complete. The combined Instrument, Spacecraft, and Ground System shall provide an end-to-end data completeness of 99.6% over periods of minutes to hours for EVE and 99.9% for AIA

The HMI observable construction requires minimizing data loss in order to create Dopplergrams and magnetograms from a series of filtergrams.

Data completeness percentage is converted into BER rate req for instrument allocation and design

INSTR, C&DH, RF, GND, GN&C

SDO Program Level Reqs (PLRs), Section A-2.1.2.2

1.2.3

For the purpose of 1.2.1 and 1.2.2 an HMI observation shall be defined as 10 minutes of science data.

Requirement addresses minimum HMI Dopplergram observation duration. Planned gaps should be kept short and as non-periodic as possible.

Req based on minimum observation duration guidance from HMI science team

HMI, C&DH, APS, RF, GND

SDO Program Level Reqs (PLRs), Section A-2.1.2.2

1.2.4

Deleted

1.2.5

Deleted

1.3

Angular Resolution & Coverage

The Instruments shall provide adequate angular resolution and image field of view to meet the Level 1 Science Requirements

N/A

1.3.1

Dopplergrams shall cover the full disk with a sampling of 0.5 arcsec per pixel, and image quality and stability that enable a resolution of <1.5 arcsec.

Drives high frequency jitter and instrument resolution. Full disk image defines FOV, absolute pointing, and data rate. Using the Rayleigh criterion for diffraction limited resolution, 0.5 arcsec pixels would give 1.2 arcsec angular resolution that would then increase for non perfect optics, pointing, photon statistics, charge spreading, etc.

HMI

SDO Program Level Reqs (PLRs), Section A-2.1.2.2.1

1.3.2

Longitudinal and vector magnetograms shall cover the full disk with a sampling of 0.5 arcsec per pixel, and image quality and stability that enable a resolution of <1.5 arcsec.

HMI

SDO Program Level Reqs (PLRs), Sections A-2.1.2.2.2 and A-2.1.2.2.3

1.3.3

AIA atmospheric images shall cover a field of view of 40 arcmin (along detector axes- 46 arcmin along detector diagonal) with a sampling of 0.6 arcseconds per pixel

Drives jitter but not pointing. 0.6 arcsec/pixel results in required spatial resoultion of 1.2 arcsec

Based on AIA proposal information. Sun diameter is ~32 arcmin as viewed by earth, resulting in ~1.3 solar radii half angle field of view

AIA

SDO Program Level Reqs (PLRs), Section A-2.1.2.3.1

1.3.3.1

Deleted

1.3.4

Deleted

1.3.5

0290
4/29/2005

Spectral Irradiance measurements must consist of integrated disk measurements over a field of view extending to 1.4 solar radii from the center of the solar disk.

Ensures complete coronal emssion coverage to <1% level.

MRD requirement 1.3.5 regarding a solar radii for EVE of 1.8 overstates the requirement to meet complete coronal emission coverage to <1% level. A solar radii of 1.4 will provide the required coverage with the existing EVE instrument design. The EVE System Requirement Document states a 1.4 solar radii.

EVE

SDO Program Level Reqs (PLRs), Section A-2.1.2.1

1.4

Spectral Resolution & Wavelength Range

The Instruments shall provide adequate spectral resolution and range to meet Level 1 spectral irradiance and atmospheric imaging measurements

N/A

1.4.1

Solar Spectral irradiance measurements shall be performed to cover the 0.1 to 105 nm range

For minimum mission success, 6 or more emissions to specify the chromosphere, TR, and corona, plus the He II 30.4 nm emission.

EVE

SDO Program Level Reqs (PLRs), Section A-2.1.2.1.1

1.4.2

Spectral resolution of 0.1 nm for a minimum of 18 emission lines between 5 - 105 nm shall be achieved

For minimum mission success, .2 nm for 6 emissions.

EVE

SDO Program Level Reqs (PLRs), Section A-2.1.2.1.2

1.4.3

Spectral resolution of 5 nm for other emission lines shall be achieved

No corresponding measurements for minimum mission.

EVE

SDO Program Level Reqs (PLRs), Section A-2.1.2.1.1

1.4.4

Atmospheric images shall cover the temperature range spanning 5000 to 20,000,000 K with 8 wavebands

Based on AIA proposal information

AIA

SDO Program Level Reqs (PLRs), Section A-2.1.2.3.1

1.5

Precision, Accuracy, & Dynamic Range

The Instruments shall provide adequate measurement accuracy over the require measurement range to meet the Level 1 Requirements

N/A

1.5.1

The Dopplergram velocity noise in quiet sun shall be <25 m/sec over a period of 50 sec.

The noise requirement flows down to a requirement that images be co-aligned on an HMI sensor to 0.1 arcsec (3-sigma) over the 50-second interval needed for one set of images to limit noise from intensity gradients and image shifts.

HMI

SDO Program Level Reqs (PLRs), Section A-2.1.2.2.1

1.5.1.1

The Doppler velocity dynamic range shall be at least +/-6.5km/s in the presence of a 3kG field.

Note that 6.5 Km/sec Doppler shift only possible in orbits where Doppler shifts are < 4kms

HMI

SDO Program Level Reqs (PLRs), Section A-2.1.2.2.1

1.5.1.2

The orbital motion shall not cause power spectrum artifacts with frequencies above 500 microHz.

To avoid artifacts the orbital period must be of the order of 5-10times longer than the period corresponding to 500 microHz or about 5 hours. This effectively requires orbits such as GEO or L1 Orbits

HMI

SDO Program Level Reqs (PLRs), Section A-2.1.2.2.1

1.5.2

Longitudinal magnetograms shall have a zero point error of <0.3 Gauss.

The zero point error refers to the disk-averaged line-of-sight field zero point noise and drives the exposure duration accuracy requirement.

HMI

SDO Program Level Reqs (PLRs), Section A-2.1.2.2.2

1.5.3

SDO-CCR-064 & 3/2/04

Longitudinal magnetograms shall have a noise level of < 17 Gauss per magnetogram.

This flows down to a requirement that images be co-aligned on an HMI sensor to 0.1 arcsec (3-sigma) over the 50-second interval needed for one set of images to limit noise from intensity gradients and image shifts.

As a result, when averaged over 10 minutes, the average noise is <5 Gauss

HMI

SDO Program Level Reqs (PLRs), Section A-2.1.2.2.2

1.5.4

Longitudinal and vector magnetograms shall have a dynamic measurement range of +/-3 kGauss

HMI

SDO Program Level Reqs (PLRs), Sections A-2.1.2.2.2 and A-2.1.2.2.3

1.5.5

The polarimetric precision in Q, U, and V should be better than 0.3% in 10 minutes.

Q, U, and V are the basic polarimetry measurements from which the vector magnetic field is derived. The noise level and systematic errors of vector magnetic field measurements are complicated functions of solar conditions and Q, U, and V. This also flows down to the image stability requirement of 0.1 arcsec (3 sigma).

HMI

SDO Program Level Reqs (PLRs), Section A-2.1.2.2.3

1.5.6

Relative calibration of the intensity of the atmospheric images shall be 10%. This is percentage accuracy of each telescope system as averaged over time (~ daily) and spatial (full solar disk) compared to the start of the mission

Minimum mission success shall be 20%. The absolute accuracy is measured on the ground compared to NIST calibrated photodioes and then relative accuracy calibrated during flight via calibration LEDs and offpoint maneuver

AIA proposal expects this accuracy to be ~5%

AIA

SDO Program Level Reqs (PLRs), Section A-2.1.2.3.1

1.5.7

Signal to noise of atmospheric images shall be 8 in quiet sun, 20 in active sun

6 in quiet sun, 15 inactive sun for minimum mission success.

AIA

SDO Program Level Reqs (PLRs), Section A-2.1.2.3.1

1.5.8

Deleted

1.5.9

SDO-CCR-064 & 3/2/04

Spectral irradiance measurements shall have an absolute accuracy of 25% (1sigma) for the daily average in 5 nm intervals and 25% (1sigma) for the brighter emission lines at the measurement cadence of 20 sec or shorter.

40% for minimum mission success. Calibration rocket flights are required to meet this requirement. Rocket flights need to occur within the time period that the EVE photometers would degrade by 17% (estimated to be about one year based on SOHO SEM
degradation rates).

EVE

SDO Program Level Reqs (PLRs), Section A-2.1.2.1

1.5.10

Deleted

1.6

Cadence

The Instruments shall provide data sets with adequate cadence to study solar phenomena on appropriate time scales

N/A

1.6.1

The dopplergrams shall have an observation cadence of 50 seconds or shorter

Drives instr observation timing, instr processing & data rate

HMI

SDO Program Level Reqs (PLRs), Section A-2.1.2.2.1

1.6.2

The longitudinal magnetograms shall have an observation cadence of 50 seconds or shorter

Drives instr observation timing, instr processing & data rate

HMI

SDO Program Level Reqs (PLRs), Section A-2.1.2.2.2

1.6.3

The vector magnetograms shall have an observation cadence of 5 minutes or shorter

Drives instr observation timing, instr processing & data rate

HMI

SDO Program Level Reqs (PLRs), Section A-2.1.2.2.3

1.6.4

The atmospheric images shall have an observation cadence of one set of 8 wavelengths every 10 seconds or shorter

Drives instr observation timing, instr processing & data rate

20 seconds for minimum success.

AIA

SDO Program Level Reqs (PLRs), Section A-2.1.2.3.1

1.6.5

Deleted

1.6.6

The spectral irradiance measurements shall have an observation cadence of 20 seconds or shorter

Drives instr observation timing, instr processing & data rate

60 seconds for minimum success.

EVE

SDO Program Level Reqs (PLRs), Section A-2.1.2.1.1

Mission Implementation