USAFA-0602 W-Band Beacon (WBB)

1. 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.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)

2. 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 WBB (USAFA-0602)Background HUSIR: Haystack Ultra-wideband Satellite Imaging Radar • Upgrade is a joint AF & DARPA Project HUSIR provides order of magnitude improvement in imaging resolution

3. 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

4. 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

5. 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. 0.12” Radiating Aperture 0.44” Input Section 2 dB Power (dB) 90° Angle (deg) WBB (USAFA-0602)Technology & Development 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

6. 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 l over 100 sec • Antenna gain variation < 0.1 dB (1 s) over angle seen during 100 sec pass • Antenna phase error < 1 lover angle seen during 100 sec pass Hardware Status: • Prototype @ 47 GHz built and tested • Q M built/tested during 06/07 Academic Year • Flight Ready: Sep 2008 Funding negotiation underway WBB Funding in $Million HUSIR Funding in $Million

7. 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

8. SNAP wide FOV Camera SNAP-1 (SSTL) • Mission • Formation Flying • Satellite inspection • Imager • 4 CMOS cameras • 0.33x0.45x0.5 m • 6.5 kg SNAP-1 Imageof Nadezhda (8 ft range) Militarily Significant Payloads Doing More in Smaller Packages Imaging Satellite Size Progression Resolutions < 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

9. 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 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 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.

10. 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

11. WBB (USAFA-0602) Backup slides

12. 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 Simulation using compact range data and W-band atmospheric phase data Thermal noise only Phase error applied Autofocused Atmospheric Phase Compensation for HUSIR dB m2

13. 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 Atmospheric Attenuation and HUSIR

14. HUSIR 96 (W-Band) 53 8 3 Near Earth & Deep Space WBB (USAFA-0602)W-Band Comparison With Other Radars } Need to image small satellite with WBB