2006 DoD SERB

U S A F A Space

Systems

Research

Center

USAFA-0602 W-Band Beacon

(WBB)

C1C Robert Bethancourt

Principal Investigator: Dr. Mark Czerwinski MIT/LLProf. William Saylor USAFA

719 333 6659william.saylor.ctr@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)

For Official Use Only (FOUO)

USAFA-0602

DoD Space Experiments Review Board (SERB)November 2006

2006 DoD SERB

U S A F A Space

Systems

Research

Center

WBB (USAFA-0602)Background

• 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

Haystack X-Band HUSIR W-Band

9.5-10.5 GHz 92-100 GHz

HUSIR provides order of magnitude improvement in imaging resolution

HUSIR provides order of magnitude improvement in imaging resolution

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

2006 DoD SERB

U S A F A Space

Systems

Research

Center

WBB (USAFA-0602)Mission / Science Overview

Operational satellite imaging

Problem: W-band radiation significantly affected by atmosphereSolution: WBB experiment will characterize atmospheric

distortions and improve signal processing algorithms

Small satellite with W-band transmitter payload for atmospheric characterization Simultaneous imaging of

small satellite for improving signal processing algorithms

Autofocused

Phase error applied

Thermal noise only

Simulation using compact range data and W-band atmospheric phase data

WBB experiment

2006 DoD SERB

U S A F A Space

Systems

Research

Center

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.

WBB (USAFA-0602)W-Band Beacon Concept

Previous Priority:• 10 of 16: 2006 Air Force SERB

Simple EHF hemispherical antenna

2006 DoD SERB

U S A F A Space

Systems

Research

Center

WBB (USAFA-0602)Technology & Development

WBB design completed• Prior laboratory design• Implemented at 41 – 47 GHz• Frequency scale to 95 GHz ( =

0.124”)• Lightweight, ~ 7 grams for antenna• Simple interface to spacecraft

processor• Size, weight, power order of magnitude

less than current instrument designs.

WBB heritage• J.C. Lee, “A simple EHF hemispheric

coverage antenna”, MIT Lincoln Laboratory Technical Report 1001, 8 August 1994

0.12”

0.44”

Radiating Aperture

Input Section

45 GHz Antenna Prototype

90°

2 dB

Angle (deg)P

ow

er (

dB

)

Demonstration of existing antenna gain pattern

2006 DoD SERB

U S A F A Space

Systems

Research

Center

WBB (USAFA-0602)Technology & Development (2)

WBB Design Requirements @ 95 GHz

• Frequency stable to within +- 0.125 MHz (1 s) over 100 sec

• Phase error < 1 over 100 sec• Antenna gain variation < 0.1 dB (1 ) over

angle seen during 100 sec pass• Antenna phase error < 1 over angle seen

during 100 sec passHardware Status:• Prototype @ 47 GHz built and

tested• Q M built/tested during 06/07

Academic Year• Flight Ready: Sep 2008

FY02 FY03 FY04 FY05 FY06 FY07 FY08 FY09 TOTAL

USAF 0.00 2.16 7.28 13.96 8.84 6.30 2.12 0.00 40.66

DARPA 0.57 0.00 7.00 11.00 10.00 10.00 4.20 2.00 44.77

HUSIR Funding in $Million

0.75 / 0.0 0.0 / 0.0 0.0 / 0.0 0.75 / 0.0

WBB Funding in $MillionFunding negotiation underway

2006 DoD SERB

U S A F A Space

Systems

Research

Center

• 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

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

• 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

2006 DoD SERB

U S A F A Space

Systems

Research

Center

Militarily Significant Payloads Doing More in Smaller Packages

Size of militarily significant payloads is a driver for HUSIR

DLR-TUBSATDLR-TUBSAT

1 m

UOSat-12UOSat-12 DLR-TUBSATDLR-TUBSATTUBSAT BTUBSAT B

0.5 m

UOSat-12UOSat-12

TUBSAT BTUBSAT B

0.15 m

Imaging Satellite Size Progression Resolutions < 10 m

Sat

ell

ite

Dim

ensi

on

(m

)

SNAP-1 (SSTL)• Mission

– Formation Flying– Satellite inspection

• Imager– 4 CMOS cameras

• 0.33x0.45x0.5 m• 6.5 kg

SNAP wide FOV Camera

SNAP-1 Imageof Nadezhda(8 ft range)

2006 DoD SERB

U S A F A Space

Systems

Research

Center

Experiment / Flight Data:• Physical Data: 3000 cm3, 3 kg,

nominal 3 W• Orbit altitude 500 200 km• Orbit inclination > 400

• Attitude knowledge < 10

• 3-axis control < 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.

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

2006 DoD SERB

U S A F A Space

Systems

Research

Center

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

2006 DoD SERB

U S A F A Space

Systems

Research

Center

WBB (USAFA-0602)

Backup slides

2006 DoD SERB

U S A F A Space

Systems

Research

Center

• Autofocus (phase compensation) techniques will mitigate most of W-band atmospheric phase error

• Residual errors– Less than 10° rms result in < -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

Atmospheric Phase Compensation for HUSIR

dB

m2

Autofocused Phase error applied Thermal noise only

Simulation using compact range data and W-band atmospheric phase data

2006 DoD SERB

U S A F A Space

Systems

Research

Center

Atmospheric Attenuation and HUSIR

• Knowledge of path length attenuation important for accurate radar cross section (RCS) measurement

– Absolute RCS values used to characterize/differentiate 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

2006 DoD SERB

U S A F A Space

Systems

Research

Center

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 Near Earth & Deep Space

3

8

53

96 (W-Band)

HUSIR

}•Need to image small satellite with WBB