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Climate Absolute Radiance and Refractivity Observatory(CLARREO)

Mission Design Options

CLARREO Formulation TeamJuly 9, 2010

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The CLARREO Climate System

DAC1

Design

DAC5

Design

DAC2 /3

Design

• Updated Instruments Fields-of-View

DAC4

Design

Solar Arrays (4)

SpacecraftBus

PayloadModule

?

• Matured RSInter-calibration Operations

• Reduced costs ?

?• Imposed

Budget Profile Constraints

Solar Arrays (4)

SpacecraftBus

PayloadModule

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Mission Design Options

• Mission Design Strategy

• Mission Concept for MCR– February MCR (DAC-4) Mission Concept– MCR (DAC-5) Mission Concept

• Phase A Mission Design Options and Trades

• Potential International / Interagency Collaboration (Steve Sandford)

Agenda

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Mission Design Strategy

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• Guidelines for budget profile-driven mission design

1. Fly one spectrometer plus GNSS RO in 2017, and then both spectrometers and GNSS RO in 2020

2. Maintain parallel development of both spectrometers

3. Pursue spacecraft and launch vehicle cost reductions

• Implementation Strategies

– Build cost-effective flexibility into the mission architecture Smaller, one-spectrometer observatories Compatibility with multiple, smaller and lower cost launch vehicles

– Take advantage of “block buys” to lower cost Develop a common spacecraft bus for all observatories Maintain a common launch vehicle interface

Mission Design Strategy

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Smaller One-spectrometer Observatories with Common Spacecraft Bus

February MCR Two-spectrometer Observatory

One-spectrometer Observatory Concept

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1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

Pegasus XL Falcon 1e Taurus XL Athena Minotaur IV+

Taurus II (Standard)

Atlas V (401/DSS)

Delta IV (Low)

Falcon 9

Mas

s to

609

km

Pol

ar O

rbit

(kg)

Launch Vehicle OptionsCapabilities to CLARREO Orbit

Launch Vehicle Compatibility for the Two-spectrometer Observatory

Certified and Under Contract with NASA Launch Services

255 kg505 kg

775 kg1,274 kg

TBD kg

~2,000 kg

Dual Manifest

Launch Vehicle Compatibility for the One-spectrometer Observatory

Dual Manifest

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CLARREO-1 CLARREO-2

Observatory Launch Observatory Launch

Option 1 2-Spectrometer(with only one) Falcon 9 2-Spectrometer Falcon 9

Option 2 1-Spectrometer Taurus XL 2-Spectrometer Falcon 9

Option 3 1-Spectrometer Taurus XL1-Spectrometer Taurus XL

1-Spectrometer Taurus XL

Mission Design Options for MCR

Option 3:• Requires only one spacecraft bus and one launch vehicle interface• Offers potential cost savings if the Taurus XL can be replaced by the Falcon 1e• Can take advantage of a Minotaur IV launch vehicle if it becomes available• Provides the most schedule flexibility, currently and in the future (sustainability)

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Mission Concept for MCR

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February MCR (DAC-4) Mission Design

DAC-4 DESIGN FEATURES

• Two identical observatories

• Observatories launched individually on Minotaur IV+ class vehicles

• Reflected solar instrument mounted on a 2-DOF gimbal

• Observatory Budgets (CBE):– Mass: 804 kg– OA Power: 691 W

• Observatories inserted into their final science orbits immediately after launch– Launch spacing 90 to 180 days

S-Band Antenna

S-Band Antenna

X-Band Antenna

GNSS POD Antenna

GNSS Ram Antenna

GNSS Wake Antenna

Reflective Solar Instrument Suite

Infrared Instrument Suite

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Objectives of DAC-5

• Provide as much science value as possible while adhering to the budget profile and schedule from NASA HQ

– Pursue cost savings that would enable both spectrometers to be developed in parallel

Use a common, smaller spacecraft bus Be compatible with lower cost launch vehicles Collaborate with international and interagency partners

• Formulate a robust, technically feasible observatory reference design

– The observatory reference design establishes feasibility for Pre-Phase A The flight observatory configuration will be developed in partnership with a

spacecraft vendor selected in Phase B Discussions with spacecraft vendors have already begun:

» Spacecraft RFI released in summer 2009» Spacecraft concept studies conducted by the Applied Physics Laboratory (APL) in

2009 and 2010» Visits to recently-awarded RSDO Rapid III vendors underway now

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Falcon 1e Compatibility

• To be compatible with a Falcon 1e launch vehicle (505 kg capability):– Configure observatory for a much smaller launch fairing – Implement observatory and architecture changes to reduce observatory CBE

mass from 804 kg (DAC-4) to <388 kg (maintains 30% margin) Reduce mass and power of all instruments Assume uncontrolled post-mission de-orbit (propellant reduction) Lower the spacecraft redundancy Reduce 2-DOF reflected solar instrument gimbal to a 1-DOF gimbal

Minotaur IV FairingFalcon 1e Fairing

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DAC-5 Infrared Observatory

Infrared Observatory Summary

• Compatible with Falcon 1e

• Three-axis stabilized– Surrey reaction wheels– Magnetic torque rods

• Redundant C&DH computers

• S- and X-band communications– 126 Gbit solid-state recorder

• Propulsion system– Orbit insertion correction– Orbit maintenance and collision avoidance

• Observatory Mass: PRELIMINARY– CBE Mass: 361 kg– Mass Margin: 40% (NTE 505 kg)

Falcon 1e Packaging

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DAC-5 Infrared Observatory

Radio Occultation Antennae

Choke RingPOD Antenna

4-panel Solar Array

Infrared Instrument Assembly

Star Tracker

Thrusters

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DAC-5 Infrared Observatory

Power Distribution and Control Unit

Reaction Wheel(1 of 4)

S-band TransceiverC&DH

Computer

Magnetic TorqueRods

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DAC-5 Reflected Solar Observatory

Reflected Solar Observatory Summary

• Compatible with Falcon 1e

• Three-axis stabilized– Surrey reaction wheels– Magnetic torque rods

• Redundant C&DH computers

• S- and X-band communications– 320 Gbit solid-state recorder

• Propulsion system– Orbit insertion correction– Orbit maintenance and collision avoidance

• Observatory Mass: PRELIMINARY– CBE Mass: 372 kg– Mass Margin: 36% (NTE 505 kg)

Falcon 1e Packaging

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DAC-5 Reflected Solar Observatory

Radio Occultation Antenna

Choke RingPOD Antenna

4-panel Solar ArrayReflected Solar

Instrument Assembly(with 1-DOF Gimbal)

Star Tracker

Thrusters

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DAC-5 Single-Axis Gimbal Concepts• CBE Mass: 12 kg• CBE Avg. Power: 17 W

LaRC InternalDesign Concept

Commercial Moog Type-5

Single Axis Gimbal Concept

DAC-5 Reflected Solar Suite Concept Design

Spectrometers

Radiator and Shield

Aperture/FilterAssemblies and Baffles

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RS Reference Inter-calibration Operations Velocity(+X)

Nadir(+Z)

Single-Axis Gimbal Would Provide “Roll” or Cross-Track Pointing

Off-Nadir (+55) Off-Nadir (-55)

Both DAC-5 concepts require “yaw” or +Z rotation by the bus

Velocity(+X)

Nadir(+Z)

Single-Axis Gimbal Would Provide “Roll” or Cross-Track Pointing

Off-Nadir (+55) Off-Nadir (-55)

Both DAC-5 concepts require “yaw” or +Z rotation by the bus

• Reference inter-calibrations conducted using a combination of:

– Spacecraft yaw maneuvers– Gimbal roll maneuvers

• ACS simulations for typical inter-calibration cases have verified performance

Case 1 Case 2Yaw angle (deg) -75 -8

Roll angle (deg) 55 55

Yaw set-up time (s) 140 46

Roll set-up time (s) 108 108

Roll slew time (s) 9 62

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RS Calibration & Verification Operations

• Proposed solar calibration approach:– The 1-DOF gimbal provides an annular

field-of-regard (FOR) for the reflected solar instrument

– During every orbit the sun will pass through this FOR

– Just prior to the sun entering the FOR, the gimbal will roll the RS instrument’s FOV into the proper location

– Relative orbital motion carries the sun through the FOV

– The gimbal returns to nadir viewing– Repeat for successive orbits

• A similar process is used for lunar verification

– Additional constraints apply(CLARREO in umbra, angular constraints)

Every lunation doesn’t provide 9 lunar

verification opportunities

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50

100

150

200

250

AD&CS C&DH Telemetry & Tracking

Electrical Power

Propulsion Thermal Structure Payload Hydrazine

CB

E M

ass

(kg)

Observatory CBE Mass BreakdownDAC-4 to DAC-5 Comparison

DAC-4 Two-spectrometer ObservatoryDAC-5 Infrared ObservatoryDAC-5 Reflected Solar Observatory

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0.15

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0.25

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0.45

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0 50 100 150 200 250 300

Dry

Mas

s Fr

actio

n (P

aylo

ad/O

bser

vato

ry)

Payload CBE Mass (kg)

Dry Mass Fraction Comparison

CLARREO-LaRCPropulsion: Yes3-axis Stabilized: YesRedundancy: High

CLARREO MCR ConceptPropulsion: Yes3-axis Stabilized: YesRedundancy: Select

CLARREO RFI StudyPropulsion: Yes3-axis Stabilized: YesRedundancy: Select

CLARREO-RFI StudyPropulsion: Yes3-axis Stabilized: YesRedundancy: Select

CLARREO RFI StudyPropulsion: Yes3-axis Stabilized: YesRedundancy: High

MSFC IR-onlyStudyPropulsion: Yes3-axis Stabilized: YesRedundancy: HighTSIS Study

Propulsion: Yes3-axis Stabilized: YesRedundancy: High

CERES StudyPropulsion: Yes3-axis Stabilized: YesRedundancy: High

APS StudyPropulsion: Yes3-axis Stabilized: YesRedundancy: Select

APL RS-onlyStudyPropulsion: Yes3-axis Stabilized: YesRedundancy: High

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• CLARREO has formulated a mission concept that achieves the science objectives within the budget and schedule constraints

– Still some remaining work to finalize the observatory MEL’s and the reflected solar instrument calibration operations

• Cost savings opportunities look promising– A one-spectrometer observatory concept was developed that enables either

an infrared observatory or a reflected solar observatory to be accommodated on a Falcon 1e launch vehicle

– Implementing a common spacecraft bus for the infrared observatory and reflected solar observatory is feasible

• The proposed mission concept with a common spacecraft bus makes the mission design insensitive, in the near-term, to which spectrometer is selected for launch in 2017 on CLARREO-1

MCR Concept Summary

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Mission Concept Progression

DAC1

Design

DAC5

Design

DAC2 /3

Design

• Updated Instruments Fields-of-View

DAC4

Design

Solar Arrays (4)

SpacecraftBus

PayloadModule

• Matured RSInter-calibration Operations

• Reduced costs

?• Imposed

Budget Profile Constraints

Solar Arrays (4)

SpacecraftBus

PayloadModule

-OR-

-AND-

2017

2020

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Phase A Mission Design Optionsand Trades

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• Radio occultation antenna maturation– Trade antenna mounting concepts to reduce

multi-path and integrate other observatory functions

– JPL is providing occultation antenna design and multi-path analysis support

• Revisit solar array configuration (again)– Trade alternative concepts seeking to:

Simplify the array configuration Reduce jitter Reduce radio occultation multi-path potential Maintain a fixed observatory c.g.

– Included in APL task order

• Continue reflected solar trades for reference inter-calibration, solar calibration, and lunar verification ops

– 1-DOF vs. 2-DOF gimbal

Key Phase A Engineering Trades

Side view of observatory in on-orbit configuration (solar array removed, all FOV’s shown)

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• RSDO spacecraft vendor data– The Rapid III spacecraft contract was recently awarded– We are visiting each Rapid III vendor to gather data on the buses that are

most compatible with the MCR mission concept, viable candidates include (among others):

Surrey Space Technologies SSTL-300 Northrop Grumman Eagle-1 Orbital LEOStar-2

– Currently planning to release a spacecraft RFI in the 2nd half of Phase A

• Launch vehicles– NASA Launch Services contract to be awarded this year– Inaugural Falcon 1e launch planned for Spring 2011

Minotaur IV and Falcon 9 had successful inaugural launches in 2010

• NASA budget updates

• Updates on international and interagency collaborations

New Data in Phase A

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• First priority is to get the second spectrometer on-orbit in 2017– Current strategy is to realize enough cost savings to build the second

spectrometer as an instrument of opportunity

• Fall-back position could be to accelerate the second spectrometer to a launch earlier than 2020

– The one-spectrometer observatory mission concept enables this option

• Another alternative is to launch CLARREO-1 on a Taurus XL or Minotaur IV, providing more mass capability to:

– Re-institute the 2-DOF gimbal on the reflected solar observatory– Increase the lifetime of either observatory to 5-7 years– Implement a large, body-fixed solar array– But the budget-profile constraint still applies

• CONCLUSION: Maintain flexibility and tight integration between science and mission engineering in Phase A to optimize the mission

Phase A Mission Options