RECONNAISSANCE PAYLOADS FOR RESPONSIVE SPACE

Transcription

1 3rd Responsive Space Conference RS RECONNAISSANCE PAYLOADS FOR RESPONSIVE SPACE Charles Cox Stanley Kishner Richard Whittlesey Goodrich Optical and Space Systems Division Danbury, CT Frederick Gilligan Goodrich Optical and Space Systems Division Chelmsford, MA 3rd Responsive Space Conference April 25 28, 2005 Los Angeles, CA

2 RECONNAISSANCE PAYLOADS FOR RESPONSIVE SPACE Charles Cox, Stanley Kishner, Richard Whittlesey Goodrich Optical and Space Systems Division, Danbury, CT Frederick Gilligan Goodrich Optical and Space Systems Division, Chelmsford, MA AIAA-RS Abstract Operationally responsive Electro-Optical (EO) imaging capability exists and is routinely used to provide intelligence information to the tactical war fighter. This capability is provided by Goodrich Reconnaissance systems having plug and play interfaces to strategic (i.e., U-2) and tactical airborne platforms. These operational systems have visible, IR and multispectral capability, and the resulting data readily interface into an existing infrastructure providing timely information to theater commanders. These airborne operational systems can be modified to provide reconnaissance capabilities from space to support the Operationally Responsive Space (ORS) vision. This paper describes these systems, summarizes some of the utility provided by them, and discusses hardware modifications and operational scenarios consistent with lowcost mission requirements. This approach, the modification of existing airborne operationally responsive EO imaging systems, provides a low cost alternative to top-down special-purpose development and leverages a continually evolving product stream to provide ORS payloads. Goodrich Reconnaissance Background Goodrich Optical and Space Systems Division (OSSD) is a pioneer in modern reconnaissance. Our heritage over the last 45 years began with the design and manufacture of the cameras for the world s first spaceborne photo-reconnaissance satellite, CORONA. This legacy of Goodrich success in space continues to the present, with examples including the Multispectral Thermal Imager, the x-ray telescope used on NASA s Chandra Observatory, star trackers and other space payloads. We continue to excel in development of special purpose EO payloads and subsystems for demanding space applications. As a leader in airborne reconnaissance, Goodrich EO sensors have provided strategic intelligence collection on the U-2 platform since its inception. Goodrich SYERS-2, a state-of-the-art multispectral sensor, is the Air Force s most advanced real-time long-range EO sensor. We have continually provided enhanced capabilities through successive generations of SYERS sensors. Our DB-110 Dual-Band Reconnaissance System is the newest airborne sensor from Goodrich. Combining visible and infrared imaging capabilities in a compact, lightweight design, this system has proven its performance day and night operationally and in demonstrations worldwide. Goodrich offers a full turnkey capability, including aircraft integration, mission planning, real-time communications, ground stations, image processing and exploitation as well as training and long-term logistical support. Combining Goodrich technologies and capabilities for space payload systems with our continually evolving operational airborne sensor line can provide low-cost payload solutions meeting Operationally Responsive Space objectives. Copyright 2005 by Goodrich Corporation. Published by AIAA 3 rd Responsive Space Conference with permission. 1

3 Airborne Sensor Overview The legacy Goodrich operational sensor developed for use in the U-2 is the Senior Year Electro-Optical Reconnaissance System (SYERS) sensor shown in Figure 1. This multi-spectral sensor system has seven imaging channels, allowing daytime and nighttime intelligence gathering. The SYERS sensor mounts internal to the U-2 aricraft via mechanical, electrical, and data interfaces supporting interchangability with the Synthetic Aperture Radar (SAR) sensor system. pinpoint targeting, tracking, and stereo imaging modes. From its typical altitude, it produces images better than NIIRS-7 at Nadir. [Image quality is quantified using the National Imagery Interpretability Rating Scale (NIIRS) 1,2, which relates the quality of an image to the interpretation tasks that image analysts are asked to do.] Goodrich recently developed the DB-110 sensor as a derivative of SYERS. With a smaller aperture than SYERS, this lightweight sensor is designed for use on tactical aircraft, and is offered in a pod-mounted configuration. This sensor system, shown in Figure 2, has been flying since 1997 and consists of a 2-axis gimbaled sensor, stabilized in pitch and roll, providing simultaneous operation in visible and infrared wavelengths. It has long focal length optics for high altitude standoff operation in both visible and IR wavelengths. Figure 1. The SYERS Sensor System Integrates Internal to the U-2 Nose The Goodrich SYERS sensor combines the information from 3 spectral bands into one color image. It currently has three baseline MSI products: All Visible Composite (Pan, Red, Green) All Infrared Composite (MWIR, SWIR1, SWIR2) Mixed Channel Composite (SWIR, Green, Pan) These bands support various intelligence tasks, such as discrimination of man-made from natural materials, camouflage identification and detection, identification of active vehicles and aircraft due to their increased thermal signature, moving Target Indication (EO-MTI), and water penetration. The SYERS sensor has a two-axis gimbal providing precison pointing along-track and cross-track for target selection in search, Figure 2. The DB-110 System Fits Within a Pod Attached to Tactical Fighter Aircraft 2

4 Goodrich integrates and delivers a complete reconnaissance system in an aircraft pod that attaches to tactical fighter aircraft via standard structural, electrical and data interfaces. In addition to the DB-110 sensor itself, this Goodrich pod system includes the sensor electronics, data recorder, data link, power distribution and environmental control system and a Reconnaissance Management System (RMS) that controls all operations of the podded equipment. The RMS is configured to operate with MIL-STD 1553B and MIL-STD 1760 interfaces. The Goodrich reconnaissance pod comprises all the structural, electrical, and communications functions of a spaceborne payload. Goodrich also provides a mobile ground station with capability for image processing and exploitation. Operational Concept for ORS The basic operational concept is to provide the tactical theater commander EO intelligence from space using assets proven in airborne operations, and using existing command and control infrastructure. The responsive space goals are to provide tactical feedback in the shortest possible time to field commanders and ultimately provide imagery on demand to enable near real time actions to be accomplished. Orbital parameters are chosen to optimize coverage of the target area of interest. More than one spacecraft may be used to further improve coverage. Imaging is performed when the target area is approximately within 30 degrees of nadir. This preserves the design ground resolution, and avoids the deleterious effects of haze on image quality. From an altitude of 300 km, this condition is satisfied for about 45 seconds of the orbit for any given target location. (Opening up the field-ofregard beyond 30 degrees can increase coverage at the cost of lower image quality.) From a 300 km orbit there are approximately 8 minutes of direct line-of-sight access to a ground station located in theater. Once the communication link is established, tasking commands are uplinked, providing coordinates of targets to be imaged. The onboard processor converts target coordinates to spacecraft pointing requirements based on current INS and GPS information. By using an agile spacecraft, the targets can be collected for a region from nadir to ±30 degrees, both along-track and cross-track. Once the first target region is encountered, the on-board processor will collect the required imagery, format the imagery and begin downlinking the data on a high-speed communications link. This approach includes a ground station in theater to accept the imagery and complete any additional image processing. The data can be viewed on monitors, transmitted to laptop computers for display and/or printed in hard copy for delivery in the field. All of this is accomplished over an approximate 8-minute time interval. In the event there is a communications problem, the data will also be recorded on-board so that it can be downloaded in the next pass. Utility from Low Earth Orbit Either the SYERS or DB-110 sensor, modified for space operation, can provide a ground sample distance (GSD) of 1 meter from an altitude of 300 km. Ground Sample Distance (GSD) is a common measure of the resolution provided by an optical system. For example, commercial remote sensing systems typically quantify their performance in terms of GSD, which is the projection onto the ground of the pixel-to-pixel spacing in the focal plane detector. Therefore, measurements of the ground are acquired on a periodic grid, where the sampleto-sample spacing is equal to the GSD. The actual informational content derived from an imaging system is more complex. Generally, the focal plane detector is designed so that the point spread function (i.e., image blur) generated by imaging optics is spanned by two 3

5 pixels, allowing one to resolve object features measuring twice the GSD. The GSD as a function of altitude is plotted in Figure 3 for a DB-110 derivative space EO sensor. GSD (meters) Imagery from a DB-110 derivative system from a 300 km altitude will be NIIRS 4.5, as shown in Figure 4. Coverage of the desired theater would be optimized by choice of orbit parameters and number of sensors/spacecraft. If imaging is restricted to within 30 degrees of the nadir ground track, a 330-km-wide region is accessible as the spacecraft passes over the target area. The EO sensor can scan out swaths that are between 6 and 10 km wide. The length of the image swath would be a function of the particular target Altitude (km) Figure 3. GSD vs Altitude for a DB-110 Derivative EO Imager Figure 4. Extrapolated NIIRS-4.5 Imagery for DB-110 Derivative EO Sensor at 300 km Altitude 4

6 During the available (nominally 45 seconds) imaging time, multiple swaths can be collected at various along- and cross-track locations, with the image data transmitted to an in-theater ground station. The maximum area coverage, assuming no time for repointing (either with a gimbal or by slewing the spacecraft), is between 1200 and 2000 square kilometers per minute. Considering re-pointing, however, we would expect to collect less than 1000 square kilometers of imagery for a collection time of 45 seconds. Assuming 10 bits per pixel, the uncompressed data associated with 1000 square kilometers of imagery can be transmitted to the ground, over a 274 Mbit/sec communications link, in under 40 seconds. Modification for Space Goodrich has been engaged for decades in the development and production of high quality spaceborne EO sensors for a wide variety of applications. These include star trackers, earth sensors, and ultraviolet, visible and infrared telescopes. A recent example of one of Goodrich OSSD s custom-developed Space payloads is the Multispectral Imaging System (MTI) launched in early 2000, pictured in Figures 5 and 6. MTI included an unobscured 3-mirror anastigmat telescope plus a sophisticated, high-accuracy absolute and relative radiometric calibration system. The 30 cm aperture, wide-field-of-view sensor provides imagery over the wide spectral range from visible through long wavelength infrared. Another example of Goodrich technology and infrastructure for spaceborne EO systems is our product line for high quality star trackers and attitude sensors. We build and deliver an average of 12 of these EO systems every year, each one consisting of the opto-mechanical telescope, focal plane, electronics, and software. Goodrich star trackers are shown in Figure 7. Figure 5. The MTI Satellite Provides Detailed Multi-spectral Images of Ground Targets Figure 6. Goodrich Developed and Delivered the MTI Payload Figure 7. Goodrich Star Trackers are Used on a Variety of Spacecraft 5

7 The technologies and capabilities used to develop, build, qualify, and deliver this payload system can be applied to our Airborne sensor line to achieve the Responsive Space Surveillance objective. The main adaptation required to the DB-110 or SYERS sensor system for responsive space is associated with the electronics. The functionality and architecture must be implemented with parts and processes compatible with the vacuum environment, which influences the means by which the electronics are cooled, and the choice of non-outgassing materials. Additionally, the modified design must provide power consumption compatible with available lowcost spacecraft busses. We estimate an orbital average power of under 200 watts for a modified SYERS or DB-110 sensor. Depending on the capabilities of the host spacecraft, the self-contained pointing and stabilization capability of the airborne sensors may be eliminated. By utilizing an agile spacecraft, the sensor mass can be kept to under 180 kg. Summary Existing high acuity airborne reconnaissance sensor designs and manufacturing infrastructure can be leveraged to deliver low-cost space EO sensors that meet the needs of Responsive Space. Modification of existing Goodrich sensors for use in space preserves their legacy of quality and reliability while minimizing the need for investment in new designs, tooling and facilities. References 1 J.C. Leachtenauer, et. al. General Image- Quality Equation: GIQE. Applied Optics 36, pp (1997). 2. L.A. Maver, et. al. Imagery Interpretability Rating Scales, in Digest of Technical Papers: International Symposium of the Society for Information Display (Society for Information Display, Santa Ana, CA, 1995), vol. 26, pp