The IRIS Project: The IRIS Project: Student Designed Imaging Satellite Student Designed Imaging Satellite

for the RASCAL Launch Vehiclefor the RASCAL Launch Vehicle

Quinn YoungSpace Dynamics Laboratory

Dr. Todd Mosher, Jared Clements, Pranay Gupta, Matt WarnerUtah State University

Background image of San Francisco Bay area courtesy TruEarth, http://www.truearth.com

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IntroductionIntroduction• IRIS is a student-designed micro-satellite mission developed for a

Space Systems Design class, spring semester 2004.• The IRIS mission is a conceptual design, based on technology and

capabilities that are either existing or under development.• Mission inspired by Peersat• Driving Requirements

– RASCAL Launch (limits mass and volume)– $10 Million cost cap, including launch and operations

• Student Design Approach– Simple spacecraft– Professionally built, student operated– Built to allow follow-on units with upgrades

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Mission OverviewMission Overview

Ground Station Segment

SpacecraftSegment

Launch SystemSegment:RASCAL

Mission OperationsSegment

ImageDistribution

Network

Mission Segment:Earth Imaging

IRIS Program:Low Cost Imaging

of Earth from Space

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Design CenterDesign Center

• The IRIS mission was designed using USU’sSpace Systems Analysis Laboratory, a concurrent design center.

PrimaryMission Trades

Imaging CommOrbitPointing

Nadir Only

Pointing Control

Altitude Inclination

High LEO(>1000 km)

Low LEO (<600 km)

Mid LEO Mid (30-60º)

High (near polar)

Low (0-30º)

Field of View

ImageSizeResolution

High(30-50 m)

Mid(50-100 m)

Very High (<30 m)

Low(>100 m)

Regional

National

Local FullSize

Compress

Highly Compress

Ground Stations

Single(Logan, UT)

Double

SunSync.

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Potential Markets for ImagesPotential Markets for Images

Market Category Potential Customer Type and Targets

Science - Weather: weather patterns, weather images- Ice: Ice flows, Iceberg location

Government (non-military)

- Disaster Response: weather imaging, disaster evaluation- Forestry Service: forest data, forest fires- Land Use: population growth, deforestation- Coastal: shoreline data, shipping routes

Military- Weather: cloud cover, snow locations, storms- Situational Awareness: location of cities or encampments- Cueing: find targets for other assets to investigate

Civilian - Media: image locations of interest- Education: geography, student mapping and imaging

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IRIS Imaging SystemIRIS Imaging System• Two Redlake ES11000 cameras

– 1 at 150 m/pixel maximum resolution– 1 at 30 m/pixel maximum resolution

• 4008 by 2672 active pixels (~11 Mega pixels)• Color (RGBG) CCD array• Commercial digital camera requiring minimal

modifications for creating space qualified version• Dual camera system allows flexibility in the types

of images captured and provides continued operation if one system fails

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Field of ViewField of View• 400 x 600 km image

footprint for 150 m/pixel camera (for regional targets, such as weather)

• 120 x 80 km image footprint for 30 m/pixel camera (for local targets, such as cities, forests, coasts)

Area of image in following

figure

Area of image in following

figure

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ResolutionResolution• Regional 150 m resolution

images and local 30 m resolution images provide a good mixture of image types for potential markets

30 m

reso

lutio

n

150

m re

solu

tion

150

m re

solu

tion

Images of San Francisco Bay area courtesy TruEarth, http://www.truearth.com

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Imaging OptionsImaging Options

• Store compressed image and download• Store full image, compress and download only

desired images after viewing thumbnails

Image Type Images/day Compression

24 bit bitmap 69 None

12 bit greyscale 139 None

Standard JPEG 559 JPEG, 25% quality loss

JPEG “thumbnail” 11742 JPEG, 90% quality loss

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Pointing ControlPointing Control

• 3-axis stabilization to within 0.5 degrees is provided using momentum wheels, with torque rods for wheel de-saturation– Error <1% of smallest side of larger image– Error <5% of smallest side of smaller image

• GPS receiver provides positional data required for image targeting

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OrbitOrbit

• 900 km altitude• 60º inclination• 103 min. period• ~14 orbits /day• 6-day revisit

rate (with slew)• Covers majority

of inhabited areas

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Communications LinkCommunications Link• Two ground stations

– Primary station in Logan, UT– Secondary station in Bedford, MA

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Design SummaryDesign SummarySubsystem Description

Mass 49 kgStructure Aluminum isogridImaging 2x 11 Megapixel cameras

30 m & 150 m resolutionTT&C 10 W S-band transmitter

1.9 Mbps downlinkC&DH Hitachi SH7709 CPUADCS 3-axis stabilizedG&N GPSThermal Active heater controlPower 39 W orbit average power

4 GaAs Solar Panels62 W-hr Lithium Ion battery

External view of theIRIS spacecraft

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Launch VehicleLaunch Vehicle

• The IRIS mission is designed specifically for launch on the RASCAL launch vehicle

Image: Tardy, Jason M., “RASCAL-Responsive Access, Small Cargo, Affordable Launch,” presentation SSC03-I-1, 17th Annual AIAA/USU Small Satellite Conference.

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ConclusionsConclusions

• The conceptual design was completed meeting all requirements and showing the potential for significant imaging capability at a very low cost

• Cost Breakdown:– Satellite Development: $5.1 M– Launch and Activation: $2.2 M– 3-year Operations: $2.4 M