Space Sextant-Autonomous Navigation and Attitude Reference System (SS-ANARS) SAMSO-508

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For Official Use Only (FOUO) USAFA-0602
USAFA-0602 W-Band Beacon (WBB)
DoD Space Experiments Review Board
(SERB)November 2006
C1C Robert Bethancourt Principal
Investigator Dr. Mark Czerwinski MIT/LL Prof.
William Saylor USAFA 719 333 6659 william.saylor.c
tr_at_usafa.af.mil Sponsor USAFA
Distribution Statement D "Distribution to US
Government Agencies and Authorized DoD
Contractors only Administrative or Operational
Use 11 October 2005. Other Requests for this
document shall be referred to the PI.
For Official Use Only (FOUO)
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WBB (USAFA-0602)Background

• HUSIR Haystack Ultra-wideband Satellite Imaging
  Radar
• Upgrade is a joint AF DARPA Project

• HUSIR Objectives
• Develop and demonstrate a ground-based wide-band
  radar system for timely on-demand imaging of
  small satellites in LEO and deep space orbits
• Input to atmospheric models
• Atmospheric distortion of W-band signals causes
  image degradation
• Simultaneous WBB and Radar Imagery
• W-Band beacon (1-way) coupled with radar data
  (2-way) will give us atmospheric truth to
  optimize algorithms atmospheric model

HUSIR provides order of magnitude improvement in
imaging resolution
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WBB (USAFA-0602)Mission / Science Overview
Small satellite with W-band transmitter payload
for atmospheric characterization
Simulation using compact range data and W-band
atmospheric phase data
Simultaneous imaging of small satellite for
improving signal processing algorithms
Thermal noise only
WBB experiment
Phase error applied
Operational satellite imaging
Autofocused
Problem W-band radiation significantly affected
by atmosphereSolution WBB experiment will
characterize atmospheric distortions and
improve signal processing algorithms
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WBB (USAFA-0602)W-Band Beacon Concept

• Objective
• Characterize the effect of atmospheric distortion
  on signal propagation.
• Improve signal processing algorithms
• Simultaneously image small satellite
• Post-pass spacecraft attitude data will also be
  used to verify HUSIR response.

Simple EHF hemispherical antenna

• Previous Priority
• 10 of 16 2006 Air Force SERB

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WBB (USAFA-0602)Technology Development

• WBB design completed
• Prior laboratory design
• Implemented at 41 47 GHz
• Frequency scale to 95 GHz (l 0.124)
• Lightweight, 7 grams for antenna
• Simple interface to spacecraft processor
• Size, weight, power order of magnitude less than
  current instrument designs.

45 GHz Antenna Prototype

• WBB heritage
• J.C. Lee, A simple EHF hemispheric coverage
  antenna, MIT Lincoln Laboratory Technical Report
  1001, 8 August 1994

Demonstration of existing antenna gain pattern
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WBB (USAFA-0602)Technology Development (2)

• WBB Design Requirements _at_ 95 GHz
• Frequency stable to within - 0.125 MHz (1 s)
  over 100 sec
• Phase error lt 1 l over 100 sec
• Antenna gain variation lt 0.1 dB (1 s) over angle
  seen during 100 sec pass
• Antenna phase error lt 1 l over angle seen during
  100 sec pass

• Hardware Status
• Prototype _at_ 47 GHz built and tested
• Q M built/tested during 06/07 Academic Year
• Flight Ready Sep 2008

WBB Funding in Million
Funding negotiation underway
0.75 / 0.0 0.0 / 0.0 0.0 / 0.0 0.75 / 0.0
HUSIR Funding in Million
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WBB (USAFA-0602)Military Relevance
WBB enables the development and demonstration of
a ground-based W-band radar system for timely
on-demand imaging of small satellites in LEO and
deep space orbits

• Space Situational Awareness (SSA)
• Derived information
• Object size and shape
• Orientation and motion
• Configuration change detection and assessment
• Component characterization
• Defensive Counterspace (DCS)
• W-Band provides order of magnitude improvement in
  capability to image small dimensions
• AF requires ability to identify potential attack
  modes against individual S/C

• Payload status changes
• Failures, separations, deployments, reactivations
• Intelligence preparation of the battlefield
• Launch and operations support

Radar imaging is frequently the onlytimely
source of this information
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Militarily Significant Payloads Doing More in
Smaller Packages
Imaging Satellite Size Progression
Resolutions lt 10 m
Satellite Dimension (m)
UOSat-12
TUBSAT B
DLR-TUBSAT
0.15 m
UOSat-12
DLR-TUBSAT
TUBSAT B
0.5 m
1 m
Size of militarily significant payloads is a
driver for HUSIR
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WBB (USAFA-0602)Flight Requirements

• Need for Spaceflight
• Orbital geometry required to provide accurate
  measurements of atmospheric scintillations and
  phase distortions
• Small satellite platform can provide known
  imaging target

• Experiment / Flight Data
• Physical Data 3000 cm3, 3 kg, nominal 3
  W
• Orbit altitude 500 /- 200 km
• Orbit inclination gt 400
• Attitude knowledge lt 10
• 3-axis control lt 100
• Small satellite highly preferred
• Auxiliary UHF / VHF TX of value
• Experiment Retrieval Required No
• Repetitive/incremental step flights No

• Requested STP Services
• Spacecraft/Sensor Integration
• Launch vehicle and integration
• Operations satellite data to Principal
  Investigator
• Minimal commands uploaded to WBB
• 0.05 kbps / 200 kb per day
• Only normal published S/C ephemera required.

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WBB (USAFA-0602)Technology/Data Application Plan

• Data Use
• WBB state-of-health, power draw, operational
  data, and satellite attitude and position
  collected by cadets
• Data provided to MIT/LL PI for use with WBB /
  HUSIR analyses
• Outcome of Successful Experiment
• Provides MIT/LL with critical beacon for HUSIR
  development and operational testing
• Improved imaging via better understanding of
  atmospheric phenomena at W band
• Measure phase distortion in real-time
• Couple with simultaneous HUSIR imaging to develop
  and validate algorithms
• Force Protection
• Ability to image small satellites critical to
  identifying potential threats
• Primary data analysis will be complete 12 months
  after launch
• Applicable research category Advanced
  Technology Demo

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WBB (USAFA-0602)
Backup slides
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Atmospheric Phase Compensation for HUSIR

• Autofocus (phase compensation) techniques will
  mitigate most of W-band atmospheric phase error
• Residual errors
• Less than 10 rms ? result in lt -40 dB sidelobes
• However, some geometries/phase errors do not
  autofocus as well
• W-Band Beacon phase data (using direct path and
  radar data)
• Refine limitations in autofocus technique with
  real (truth) data
• Phase error can be determined separately from
  autofocus
• Assess autofocus performance on a known small
  satellite
• Scatterer locations known

dB m2
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Atmospheric Attenuation and HUSIR

• Knowledge of path length attenuation important
  for accurate radar cross section (RCS)
  measurement
• Absolute RCS values used to characterize/different
  iate satellites
• For image focusing, variable attenuation is less
  important than phase fluctuations
• Atmospheric attenuation consists of several main
  components
• Oxygen, water vapor, liquid water
• HUSIR will have a slaved water-vapor radiometer
  adjacent to antenna to measure water content
  along line of sight
• Oxygen absorption component can be estimated from
  temperature and pressure
• Measurement of water vapor typically more precise
  than that of liquid water (rain, clouds, etc.)
• Calculated attenuation will be used to tune radar
  data
• WBB will provide an excellent means to check WVR
  attenuation estimation method
• Like radar, beacon strength sensitive to
  atmospheric absorption
• Other method of validation sphere (constant
  cross-section) tracking

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WBB (USAFA-0602)W-Band Comparison With Other
Radars
Radar Haystack HAX
Frequency (GHz) 10 (X-Band) 16.7 (Ku-Band)
Sensitivity (dB) 56 36
Bandwidth (GHz) 1 2
Resolution (cm) 25 12
Satellite Imagery Range Profiles Near Earth Deep Space Near Earth

• Need to image small satellite with WBB