StarNav
Advanced CMOS Star Trackers:
enhanced accuracy, reliability and speed
John L. Junkins
Texas A&M University
May 16, 2002
StarNav I, II, and III Advanced Star Tracker Systems
• The StarNav sensors combine novel hardware and software to
establish a new generation of smart navigation sensors
– Outputs 5 m rad 3 axis accuracy
– Split field of views optics means one camera sees two orthogonal
starfields simultaneously => cost reductions, accuracy improvements
– CMOS Active Pixel Sensor => rad. tolerance and high frame rates
– Fast/reliable star identification algorithm for lost in space (LIS) case,
first algorithm capable of reliable LIS star ID for magnitude six stars in a
small fraction of a second.
– Recursive on-orbit autonomous self-calibration => greatly enhanced
reliability, autonomy and accuracy, esp. for long missions.
• StarNav I: Proof of Concept Experiment for STS 107 (July ’02)
• StarNav II: 10 HZ GIFTS Mission StarTracker (Circa 2003)
• StarNav III: 60HZ Gyroless Attitude and Rate Sensor (SLI)
May 16, 2002
GIFTS Software TIM, College Station, TX
Slide No. 2
STARNAV: Recent Legacy
Research and development at TAMU from
laboratory brassboard to flight prototype
• A Micro-Star Tracker for Micro-Spacecraft
STARNAV I: Lab Test Configuration
MICRO STAR TRACKER
FRAME GRABBER
1999
CAMERA HEAD
SITe SIA502AB 512 x 512 CCD array
peak quantum efficiency 0.85
LENS
• A self-calibrating Smart Sensor, outputs attitude,
not image data
• Striving for Significant Advances:
• Low Cost
• Light Weight
• Low Power
• High Accuracy
STS 107 StarNav I Flight
Experiment
SINGLE BOARD COMPUTER
586-133, 32 Mb DRAM, 40 Mb FLASH
STARNAV I – On-orbit demonstration of advanced
“Lost in Space” algorithms and data collection for
recursive
on-orbit calibration
implementation.
May 16, 2002
GIFTS Software TIM, College Station, TX
2002
Slide No. 4
StarNavII Split Field of View Star Camera
for the EO-3 GIFTS Mission
May 16, 2002
The StarNav II camera
simultaneously images star fields
from two parts of the sky, real-time
identification of the star patterns, and
determination of 3 axis attitude with
a precision of 5 mrad (1s).
GIFTS Software TIM, College Station, TX
Slide No. 5
STARNAV II (TCP’s EO-3 Prototype)
Dual Field of View Tech Demo Success!
FOV 1
Dual Field-of-View
Star Tracker Concept
Patents applied for.
• Two star field images are superimposed
onto a single image plane.
• This concept eliminates the unavoidably FOV 2
poor sensitivity of a single star tracker in
resolving rotations about the optical axis
without incurring the mass penalty of a
second star tracker.
• The star images of each field-of-view are
“tagged” optically via cylindrical meniscus
lenses, resulting in elliptical star images.
Spots are then sorted by shape to
determine the FOV of origin.
May 16, 2002
Tom Pollock’s night sky expmt, Oct, 2000
GIFTS Software TIM, College Station, TX
Slide No. 6
STARNAV
Dual FOV Testbed
Dual Field-of-View
Star Tracker
Engineering Model
for Concept Verification
Status:
assembled
bench tested
night sky tested
May 16, 2002
GIFTS Software TIM, College Station, TX
Slide No. 7