Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified LADAR Measurements of the International Space Station LADAR Guidance for Autonomous Rendezvous and Docking Colin L. Smithpeter ( ), Robert O. Nellums, Steve M. Lebien, George Studor*, George James* Sandia National Laboratories *NASA Johnson Space Center

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified Laser Radar Laser Radar provides angle, angle, range images of target Potential for small, standalone sensor in AR&C –Range & bearing with each image, day or night, uncooperative targets –6 DOF velocities from sequential images –Target vehicle orientation from 3D images X:+2 Y:-2 Z:+20  X:-0.2  Y:0.0  Z:+2

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified Key Points Laser Radar is accurate, rapid, and small –What are the issues? Scanning Versus Scannerless –Virtually all existing ladar capabilities utilize scanning –A unique, scannerless laser radar has been developed by Sandia National Laboratories. Laser Dynamic Range Imager (LDRI) Overview –Scannerless demonstration on STS 97 Mission in AR&C LADAR concept Next Generation micro LADAR

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified Laser Radar Issues Optical energy per pixel measurement –Minimum signal requirement depends upon ladar architecture, including quantum efficiency, noise, and background. Typical to require 100s of photons, but a single photon is potentially feasible. –Required illumination, given required signal, tends to vary directly with number of pixels, range 2 and FOV 2. Energy can become prohibitive at long range. –Temporal and spectral filtering required to reduce solar background Target Albedo –Specular materials, such as Mylar, can be very difficult to detect –Diffuse materials, such as brushed metal or beta-cloth, provide reliable returns –Retro-reflective cubes or tapes greatly enhance return from range

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified Scanning Versus Scannerless Why Scanning –Single-channel EO can incorporate sophisticated readout of return waveform –Single axis can incorporate spatial filter: IFOV can be much smaller than pixel spacing, to reduce solar background –Variable FOV, pointing, and pixel spacing Why Scannerless –Focal plane eliminates bulk and reliability issue of scanning mechanism –Focal plane enables fast image acquisition. Single flash feasibility.

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified Target Return Detected Laser Return Processed Sensor Output LADAR Sensor Challenge: Measure laser pulse return time in each pixel with nanosecond accuracy –Nyquist indicates 2 GHz bandwidth, thousands of samples Sandia Approach: Detect laser time of flight by sampling waveform with limited number of frequencies –Heterodyne laser return with AM receiver –Reduce complexity and bandwidth, improve resolution and sensitivity –10 MHz BW for nanosecond accuracy Example: Simulated return through obscuration Obscuration Return

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified Scannerless Range Imaging Range Encoded Image t J t T 1/  Intensity Pulse Launch Time Sin 

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified Example: M60 tank at 250m in daylight Phase Intensity

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified Laser Dynamic Range Imager Motivation: Structural Dynamics of ISS Assembly, control, and operation of large, flexible ISS structure requires validated structural models –High density of structural modes –Limited instrumentation for on-orbit validation –Supplement with non-contact measurement  Image vibration motion with LADAR sensor Secondary applications: Inspection, proximity operations navigation

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified LDRI Mission Requirements Image natural mode frequency and amplitude –Induce vibration with Shuttle thruster firing Replace Intensified Video Camera Illuminator –Weight 4.4 lbs, Size 5(w)x3.5(h)x9(l) inches –Eye safe laser illumination, 40 degree field of view Dynamic range accuracy of 0.1 inch, frequencies to 7 Hz ITVC/LDRI Assembly

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified On-Orbit Images Intensity Hi-Frequency RangeAbsoluteSurface Rendering

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified Solar Array Measurements IntensityRange

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified ISS Range Movie Grayscale cycles every 107 cm of range

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified On-Orbit Vibration Data

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified On-Orbit Vibration Data

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified LDRI Summary Developed a space qualified LADAR –5 lbs, Size ~ 10x5x4 inches –0.1 inch range resolution, 640x480 pixels –Eye safe laser illumination, 40 degree field of view –Capturing 30 fps for vibration data to 7.5 Hz Flown on STS 97 –Measured vibration amplitudes of 0.1 inches –Demonstrated inspection/characterization of structures Funded by JSC engineering division and HEDS Shuttle upgrades office.

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified AR&C Concept Acquisition of target vehicle –Target: 1km range, 3m diameter, non-cooperative –Sensor: 10nm SBW, 10cm aperture, 400ns gate –Worst case Radiometry: at edge of 20 deg FOV, 5% albedo –Require 500 photons per pixel for reliable detection –Required laser energy is 10mJ per pulse –Solar background drives required laser energy to 80mJ/pulse

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified AR&C Concept Rendezvous –Continuous updates on range, bearing, and 6 DOF rates –Bearing resolution improves with decreasing range  5 arc min at 250m  Sub-meter range accuracy –Update rates to 30 Hz Docking –Increase FOV to 90 deg –Determine 6 DOF orientation from 3D image  Extract features and correlate with known features  Correlated current 3D image with reference model –100 pixels across target at 10m separation, sub-cm range accuracy, 0.2 deg rotational accuracy

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified Required LDRI development Daylight Illuminator –Q-SW doubled YAG laser Electronics Upgrade –Processor and digital interface –Digital camera Autonomous Algorithms –Range, bearing, and rates –Orientation Issues –Specular surfaces –Motion artifacts Sandia Micro Laser

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified Future LADAR Technology Current Issues –Motion distortion –Eye safety & stealth –Required laser energy –Complexity and cost –Multiple returns Solution: –Miniaturize receiver to focal plane array chip –New algorithms utilizing multiple frequencies

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified Near-term Flash LADAR Completed prototype Size: 7x10x10 inches, 15 lbs Electronics 4 camerasOptical block Top down view

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified Micro LADAR Focal plane array of detectors Instant 2 frequency sampling by parallel mixers –Range and passive image sensor –Bond visible, NIR, or IR detectors Detector

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified Status : 2x128 prototype fabricated by JPL with NASA & DARPA funding Alternate Sandia approach 1x128 array Demonstrated basic function (TRL 3) FPA Impact Instantaneous imaging  Freeze motion Integrated FPA  Low-cost and compact Enhanced sensitivity  Long Range ( >2km) IR operation  Eye-safety and stealth Dual IR & 3D  Enhanced ATR capability Foliage penetration  Enhanced operability Objective: Develop IC detector array for instantaneous range imaging Sandia Technology : Sample laser return with selected frequencies –Increase resolution by 10x –Eliminate threshold detection  Reduce false returns  Enhance sensitivity & dynamic range Micro LADAR 2x128 Prototype

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified FPA Sensor Laser return sampled instantly with parallel mixers –Hybrid array architecture for operation in IR and dual mode passive and active imaging –Store heterodyne product in pixel for readout –Single pulse (flash) imaging avoids motion artifact –Currently at TRL 3 8x16 FPA Prototype

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified First Device Testing Measure laser response Sweep laser time of flight –Detected modulation indicates basic operation –Gating working at 1  s Range sweep at 3 MHz modulationTypical timing and output 2x128 Prototype

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL Unclassified Micro LADAR AR&C Impact Single pulse illumination – no motion artifact Near IR operation for eye safety on manned mission Reduce size and complexity –System dominated by laser size Background rejection –Reduce laser energy –Enable CW diode laser illumination