SDA HQ085021S0001-12 COSAS STTR-vFINAL.pdf

Small Business Technology Transfer (STTR) and

Opportunity Announcement

HQ085021S0001-12

July 12, 2021

Commercial SAR and Scatterometry (COSAS)

Which program will fund this topic?

STTR

DoD Technology Areas:

Space Platforms, Sensors

RT&L Technology Focus Areas:

Space

What type of proposals will be accepted?

Phase I

I. INTRODUCTION

The Space Development Agency (SDA) is issuing an SBIR/STTR Opportunity (SBO) inviting submissions of innovative research concepts supporting the advancement of our national defense space capabilities. This SBO pertains to Space Based Environmental Monitoring (SBEM).

This SBO is issued under the SDA Broad Agency Announcement (BAA) for SBIR/STTR, HQ085021S0001. All proposals in response to the technical area(s) described herein must be submitted in accordance with the instructions provided under HQ085021S0001, found here:

https://go.usa.gov/x724e.

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export

Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items.

Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 3.5 of the Announcement. Offerors are advised that foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

a. Eligibility

Please refer to Section 3.1, Eligible Applicants, of HQ085021S0001 for full eligibility requirements.

This SBO, HQ085021S0001-12, is being funded by the STTR program. The research objective of this SBO is also issued as an SBIR opportunity under SBO HQ085021S001-

11. Please review Section 3.1 subparagraph (b) and (c) of HQ085021S0001 for full eligibility requirements of the SBIR and STTR programs.

b. Anticipated Structure/Award Information

Please refer to Section 1, Funding Opportunity Description, and Section 2, Award Information, of HQ085021S0001 for additional details on the structure of this opportunity and prospective awards.

For this SBO, SDA will accept Phase I proposals for cost of up to $250,000 for a 12-month period of performance.

Proposers awarded a Phase I contract will be eligible to submit a proposal for Phase II and will be contacted by SDA at the appropriate time during their Phase I period of performance. If selected, Phase II will have a cost of up to $1,700,000 for a duration not to exceed 24 months.

c. Proposal Preparation Instructions

Proposers should refer to Section 4, Application and Submission Information, of HQ085021S0001 for detailed proposal preparation instructions. Proposals that do not comply with the requirements detailed in HQ085021S0001 and the research objectives of this SBO are considered non-conforming and therefore will neither be evaluated nor considered for award.

The technical volume of proposals shall not exceed 20 pages. Commercialization strategy shall not exceed five pages. This should be the last section of the Technical Volume and will not count against the 20-page limit. Please refer to Appendix A of HQ085021S0001 for detailed instructions on Phase I proposal preparation.

d. Evaluation of Proposals

Please refer to Section 5, Evaluation of Proposals, of HQ085021S0001 for a full description of the proposal evaluation and selection process.

e. Due Date/Time

Full proposal packages (Proposal Cover Sheet, Technical Volume, and Cost Volume inclusive of supporting documentation) must be submitted via the DoD SBIR/STTR Innovation Portal (DSIP) per the instructions in Section 4, Application and Submission Information, of HQ085021S0001 no later than August 26, 2021 at 12p.m. EST.

f. Company Commercialization Report

Please refer to Appendix A, Section A.3.f of HQ085021S0001 for Company Commercialization Report guidance.

II. TOPIC OVERVIEW

a. Objective

Based upon the set of design parameters and technical performance measures (TPMs) listed herein, adapt, for lowest capital cost, the single look complex (SLC) synthetic aperture radar (SAR) payload of a notional commercial small satellite constellation to the mission of supplying timely ocean surface vector wind (OSVW) and tropical cyclone intensity (TCI) data to the warfighter.

b. Description

SDA is responsible for orchestrating the development and fielding of the DoD’s future threat-driven National Defense Space Architecture (NDSA), a resilient military sensing and data transport capability via a proliferated space architecture primarily in low Earth orbit (LEO). To achieve this mission, SDA uses novel approaches to accelerate the development and fielding of military space capabilities necessary to ensure U.S.

technological and military advantage in space for national defense.

Background

Weather conditions critically impact the effectiveness of DoD missions. Today’s accurate weather forecasts rely on timely observations from space. Although commercial SBEM data as a service has expanded in recent years, Congress mandates that the DoD acquire organic resources to execute high-priority SBEM missions on short timelines that are consistent with joint force operations. A high priority mission for naval surface operations is measuring OSVWs and TCI.

Historically, OSVWs and TCI data for DoD missions has been measured by microwave instruments on board LEO satellites such as those of the Defense Meteorological Satellite Program (DMSP) constellation. These instruments fall into two categories: passive and active. Passive radiometers employ a rotating aperture and receiver to image the upwelling microwave brightness temperatures of the world’s oceans and the overlying atmosphere. They relate this data to OSVW and TCI in data processing algorithms. The Special Sensor Microwave Imager (SSM/I) and Special Sensor Microwave Imager Sounder (SSMIS) payloads on board DMSP are prime examples [1]. The most successful active microwave instrument for measuring OSVWs is the scatterometer.

Scatterometry was discovered anecdotally during World War II when operators noticed that clutter in ocean surface radar images was affected by winds [2]. Scatterometry technique advanced when it was later determined that OSVWs relate to magnitude and direction of radar energy that is backscattered from the rough ocean surface. The first practical space-based scatterometer was demonstrated during NASA’s Skylab missions in 1973-74. Today, scatterometers are effective and versatile in measuring not only OSVWs, but more recently, soil moisture and patterns of freezing and thawing in the Arctic. Recent examples include the NASA Scatterometer (NSCAT), QuickScat, and SeaWinds instruments; in addition to the ESCAT on board the European Remote Sensing satellites ERS-1 and 2 [2].

A modern scatterometer payload has several features to yield OSVWs and TCI from measurements of radiation backscatter from space. Scatterometers process backscatter measurements using a geophysical model function (GMF) that yields wind speed and direction [2]. The backscatter signal that the instrument receives does not contain sufficient information to uniquely determine wind direction from the GMF [2,3]. To resolve the ambiguity in wind direction, modern scatterometers feature discrete beams emanating from fore and aft antennas or a pair of beams emitted by a single rotating reflector [3,4]. Furthermore, the instrument may measure multiple polarizations in place of (or in addition to) multiple beams [2]. For this approach to be effective, the instrument must be calibrated with knowledge of the beams’ direction such that the origin of the backscatter is known to high accuracy [4]. The third feature is platform or beam steering to compensate for Doppler shift in the return signal [2]. When properly coordinated in the instrument, these features enable space-based scatterometers to map ocean surface wind speed and direction with 25 – 50 km resolution and wind speed accuracy of approximately ±3 m/s [2,6].

DMSP will operate until 2025. Replacing it in the coming years is the Weather System Follow-On Microwave (WSF-M) constellation. In 2014, the Joint Staff established OSVW and TCI measurement gaps that WSF-M and others must fill in the wake of DMSP [5]. They are listed with other technical performance measures (TPMs) in the table below.

SDA Commercial SAR and Scatterometry (COSAS) Mission TPMs

Parameter Value Units Comment Regional Coverage 30E to

80W deg longitude

Defines the geographic region that requires coverage from the

COSAS LEO SBEM

constellation with the maximum revisit time listed below

Measurement Uncertainty:

Wind Speed

≤ 1.5 m/s For wind speed 5 – 7 m/s and 7 – 10 m/s

Measurement Uncertainty:

Wind Speed

≤ 2 m/s For wind speed 10 - 25 m/s

Measurement Uncertainty:

Wind Speed

N/A m/s Best effort for wind speed 25 - 60 m/s [13]

Measurement Uncertainty:

Wind Direction

≤ 30 deg For wind speed 5 – 7 m/s

Measurement Uncertainty:

Wind Direction

≤ 20 deg For wind speed 7 – 10 m/s

Measurement Uncertainty:

Wind Direction

≤ 15 deg For wind speed >10 m/s

Refresh < 6 hours Maximum time to revisit the storm center location plus 100 km in all directions within the region of coverage; individual SAR swath width must be large enough to facilitate required refresh rate from a family of systems (FoS)

Latency 3 hours Time elapsed from sensor collection to arrival at DoD data processing center

Horizontal Spatial Resolution ≤ 10 km Radius of the smallest wind vector cell (WVC) inside of which wind speed and direction is invariant, thus corresponding to wind vector resolution

Accuracy (Radiometric Calibration)

1 dB

Precision (Noise-Equivalent

NRCS)

< -30 dB

Platform Geolocation Accuracy

≤ 7 km

SDA is exploring plans to complement WSF-M coverage to realize persistent, global OSVW and TCI nowcasts every six hours or less. Since it is presently uneconomical to deploy an additional NDSA layer for this purpose, SDA is exploring alternative approaches. One approach is Commercial Augmentation of the NDSA. With Commercial Augmentation, SDA leases privately-owned satellites to perform a dedicated national security mission(s) for all or part of their design life. Data from Commercial Augmentationsatellites is delivered through optical crosslinks to the NDSA Transport Layer to meet the warfighter’s nowcast requirement. The WSF-M will employ a passive microwave radiometer. Radiometers and active scatterometers are not prevalent in commercial constellations. What is more common and therefore a promising candidate for a program of Commercial Augmentation for OSVW and TCI, is synthetic aperture radar (SAR). A space-based SAR is similar to a scatterometer in many respects, but there are important distinctions. The backscattered energy measured by a SAR is referred to as the normalized radar cross section (NRCS) of the ocean surface [2]. Scatterometers typically operate in the C or Ku-band. C-band scatterometers have an advantage in that they are much less affected by heavy rain than Ku-band scatterometers [2]. In contrast to scatterometers, nascent commercial SAR payloads operate almost exclusively in X-band.

A space-based SAR can create a map of NRCS along the earth’s surface with an order of magnitude greater spatial resolution than a scatterometer [2]. This greater resolution is particularly valuable in narrow straits and waterways, for example, where scatterometer measurements can be biased by coastal islands, ice shelves, rock formations, and other littoral landscape features [6]. High resolution, however, places a greater demand for on-board memory when surveying large areas [7]. More importantly, unlike a scatterometer, a typical compact commercial space-based SAR payload has a single aperture, a single polarization, and a single-azimuth view (i.e., single look), and thus cannot characterize high winds, nor can it solve the underdetermined problem to gauge wind direction and speed at high resolution without changes in payload design and approach to data processing.

Several methods have been developed in recent years to overcome the underdetermined problem in wind retrieval with a SLC SAR. The SLC refers to the fact that each image pixel is represented by a complex number with amplitude and phase information [11]. A concise summary of these methods is listed in [8]. The first method takes advantage of the tendency for surface winds to create streak features in the ocean surface that are aligned with the wind. This method, while valid, is not universal for all conditions and requires additional information to determine the ±180-degree orientation of the wind vector [8]. The second method resolves the ambiguity by referencing the SAR wind data to a priori information from numerical weather prediction (NWP) models [6]. Portabella, Stoffelen, and Johannessen describe a Bayesian Statistical Wind Retrieval Approach (SWRA) that minimizes a cost function based on NWP model wind speed and direction information that is linearly interpolated to a comparable dimensional resolution as the SAR wind speed retrieval algorithm. Although more accurate than previous methods, the SWRA is systematically biased and tends to underestimate (by less than 1 m/s) low-speed crosswinds [6]. However, this is sufficient for the DoD mission that requires a maximum OSVW speed accuracy of ±2 m/s. The third method is based on a polarimetric SLC SAR system that incorporates co- and cross-polarized signals [7,8]. Zhang et al describe an algorithm that retrieves wind speed and direction from this signal information by calculating two parameters: NRCS and the polarization correlation coefficient (PCC) for co- (i.e., VV or HH) and cross-polarization (i.e., VH or HV) states [8]. Wind direction is determined by comparing the even symmetry of the NRCS to the odd symmetry of the PCC, as functions of wind speed. These proven methods open the possibility of accurately measuring OSVW and TCI for various commercial SAR payload designs.

Measuring TCI with SLC SAR presents another difficulty. A Category 5 hurricane or tropical cyclone is defined by the Saffir-Simpson Hurricane Wind Scale as a storm with sustained winds of approximately 67 m/s (150 mph) [9]. Many commercial SLC SAR payloads emit and receive a co-polarized beam, HH or VV. A co-polarized beam has been used in scatterometer payloads because it produces a backscatter signal that has a much higher signal to noise ratio (SNR) than a signal produced by a cross-polarized beam at low wind speed [10]. Fois et al. describe how a co-polarized channel suffers from “incidence angle-dependent and azimuth angle-dependent signal saturation and dampening,” which causes a SAR to be insensitive to changes in wind speed above 25 m/s [10]. For this reason, cross-polarization is valuable for measuring TCI.

Statement of Work

Given this background, the value proposition for this project is to remove the technical barriers for nascent commercial SAR constellations and to enter a new market for OSVW and TCI data delivered by Commercial Augmentation of the NDSA. To realize this value, the project shall investigate the following.

Task 1: Design a notional commercial SAR constellation that satisfies the TPMs in terms of revisit rate, coverage, and latency.

Task 2: The design parameters for a notional commercial SAR payload are shown below.

Notional Commercial Small Satellite SLC SAR Payload Design Parameters

Parameter Value Units Comment Operating Frequency 8-12 GHz X-Band

Maximum Incidence Angle 60 deg Angle of SAR energy incident upon the ocean surface from [14]

Minimum Incidence Angle 20 deg

Polarization HH N/A Horizontal

Total Payload Mass ≤150 kg Total mass of the instrument and its supporting subsystems, including the antenna

Average Power <250 W

Stowed Volume <725,000 cm3 Approximately 90 cm3, excluding the antenna

Lifetime on Orbit 2 Years

The second task is a trade study that minimizes the cost of retrofitting (i.e., physically and/or virtually modifying) the notional payload design to accurately and unambiguously measure OSVWs and TCI according to the mission TPMs.

Task 3: To validate the optimal payload design, the project should adapt and mature an X-band GMF, such as XMOD [13-14]. The GMF relates NRCS to the ocean surface wind vector, and SLC SAR sensor parameters. In so doing, the project should apply an appropriate method for resolving wind direction ambiguity. This task also includes a credible, efficient method of evaluating payload-specific GMF tuning coefficients that may be incorporated in the firmware of the future flight payload [11-14]. With an example tuned GMF, the project should characterize OSVWs in terms of measurement uncertainty and compare to the TPMs listed above.

The results of this project will facilitate adding OSVW and TCI capability to commercial SAR constellations for delivery to the warfighter in an NDSA Commercial Augmentation model. The next sections describe the project phases.

c. Phase I (12 months)

This project will address the SDA mission need by producing a Phase I end item data package (EIDP) comprised of a payload design and analysis report and Phase II development plan. The Phase I design and analysis report shall include a narrative that describes the work performed in support of Tasks 1, 2, and 3, including approach and technical rationale.

Design and trade study information related to Task 1 and 2 shall include an explanation of the trade study process, parameters, and assumptions. The candidate payload design description shall include conceptual computer aided design (CAD) renderings, drawings, specifications, calibration curves, and other documents that define the instrument and its supporting subsystems in sufficient detail to inform future commercial payload developments. For analysis work in Task 1, 2, and 3, the report should relate the objective/hypothesis, parameters, assumptions, initial conditions, and procedure. Analysis results shall be compared to requirements in a summary of findings, conclusions, and recommendations.

The Phase II development plan shall outline activities that build on the results of Phase I.

These activities include developing example tuned GMFs, characterizing wind data, and assessing results. The development plan shall discuss in detail, the approach and process for evaluating GMF tuning coefficients. Lastly, Phase II advances the conceptual design of the optimal payload to include a preliminary design of the flight instrument and its supporting subsystems.

Phase I Schedule/Milestones/Deliverables

Month 1: Project kickoff briefing to SDA Emerging Capabilities Cell Chief detailing the proposed technical approach and schedule with milestones.

Month 4: Quarterly progress report including technical progress to date and the technical plan for the remainder of Phase I.

Month 6: Interim progress briefing to the Emerging Capabilities Cell Chief detailing technical progress to date, significant tasks accomplished, major risks, a technical plan for the second half of Phase I, and any potential issues or problem areas that require the attention of SDA.

Month 7: Quarterly progress report including technical progress to date and the technical plan for the remainder of Phase I.

Month 10: Quarterly progress report including technical progress to date and the technical plan for the remainder of Phase I.

Month 12: Final technical progress report and briefing of the Phase I EIDP described above and Phase II development plan.

d. Phase II (12 months)

Phase II develops examples of tuned GMFs for the optimal payload using the method established in Phase I. Phase II applies the example tuned GMFs to characterize wind data and compare results to the TPMs. The preliminary design of the optimal payload shall comprise computer aided design (CAD) renderings, detailed drawings, specifications, and other documents that define the instrument and its supporting subsystems in sufficient detail to enable prototyping of the flight instrument in Phase III.

The Phase II EIDP consists of a final report that includes the preliminary design of the optimal payload and details of the validated GMF with a tuning process that is easily mapped to the future flight payload.

Phase II Schedule/Milestones/Deliverables

Month 1: Phase II kickoff briefing to SDA Emerging Capabilities Cell Chief detailing the proposed technical approach and schedule with milestones.

Month 4: Quarterly progress report including technical progress to date and the technical plan for the remainder of Phase II.

Month 6: Interim progress briefing to the Emerging Capabilities Cell Chief detailing technical progress to date, significant tasks accomplished, major risks, a technical plan for the second half of Phase II, and any potential issues or problem areas that require the attention of SDA.

Month 7: Quarterly progress report including technical progress to date and the technical plan for the remainder of Phase II.

Month 10: Quarterly progress report including technical progress to date and the technical plan for the remainder of Phase II.

Month 12: Final technical progress report and briefing of the Phase II EIDP described above.

e. Flight Testing and Dual Use Applications (Phase III)

Phase III work would transition of the optimal payload to a commercial SAR constellation operator. Transition may be direct to Commercial Augmentation operations or, if the prime contractor is not a commercial SAR constellation company, transition may involve sale of the intellectual property and/or consultation services to the constellation company. The DoD/military application is OSVWs and TCI data delivered to the warfighter via Commercial Augmentation of the NDSA to inform military operations around the world.

f. References

1. U.S. Air Force Space Command (Archived), Defense Meteorological Satellite Program, https://www.afspc.af.mil/About-Us/Fact-Sheets/Article/249019/defense-meteorological-satellite-program, March 22, 2017.

2. Scatterometer Instrument Competence Centre, The SCIRoCCo Scatterometry Handbook, SCI-PUB-14-001-v01, http://scirocco.sp.serco.eu, 2017.

3. Maurer, J., What Is Scatterometry?

http://www2.hawaii.edu/~jmaurer/scatterometry/what_is_scatterometry.html, University of Hawaii (undated).

4. Jet Propulsion Laboratory, Scatterometry, https://winds.jpl.nasa.gov/aboutscatterometry/history/, California Institute of Technology (undated).

5. U.S. Department of Defense, United States Air Force Report to Congressional Committees: Department of Defense Plan to Meet Joint Requirements Oversight Council Meteorological and Oceanographic Collection Requirements, August 2016.

6. Portabella, M., Stoffelen, A. & Johannessen, J.A, Toward an Optimal Inversion Method for SAR Wind Retrieval. in J. Geophys. Res. 107(C8), pp. 1–13, 2002.

7. Longépé, N., Mouche, A., and Ferro-Famil, L., Co-Cross-Polarization Coherence Over the Sea Surface from Sentinel-1 SAR Data: Perspectives for Mission Calibration and

Wind Field Retrieval, in IEEE Transactions on Geoscience and Remote Sensing (accepted for future issue), pp. 1-16, 2021.

8. Zhang, B., et al., Ocean Vector Winds Retrieval from C-Band Fully Polarimetric SAR Measurements, in IEEE Transactions on Geoscience and Remote Sensing, 50:11, pp.

4252-4261, 2012.

9. National Hurricane Center and Central Pacific Hurricane Center, Saffir-Simpson Hurricane Wind Scale, https://www.nhc.noaa.gov/aboutsshws.php (undated).

10. Fois, F., Hoogeboom, P., Le Chevalier, F., and Stoffelen, A., Future Ocean Scatterometry: On the Use of Cross-Polar Scattering to Observe Very High Winds in IEEE Transactions on Geoscience and Remote Sensing, 53:9, pp. 5009 – 5020, 2015.

11. European Space Agency, Sentinel Online: Level-1 SLC Products, https://sentinel.esa.int/web/sentinel/technical-guides/sentinel-1-sar/products-algorithms/level-1-algorithms/single-look-complex, 2021.

12. European Space Agency, Earth Online: TerraSAR-X ESA Archive Data, https://earth.esa.int/eogateway/catalog/terrasar-x-esa-archive, December 15, 2020.

13. Shao, W., and Li, X., Characteristics of NRCS on X-Band SAR under High Winds together with Rain in Proceedings of the 2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), pp. 4599-4602, 2016.

14. Ren, Y., He, M., and Lehner, S., Wind Field Retrieval over the Ocean Using X-Band Polarization SAR Data in Proceedings of the Second IITA International Conference on Geoscience and Remote Sensing, 4 pp., 2010.

g. Keywords

Low Earth Orbit, Ocean Surface Vector Wind (OSVW), Satellite, Scatterometer, Single- Look Complex (SLC) Synthetic Aperture Radar (SAR), Space-Based Environmental Monitoring (SBEM), Tropical Cyclone Intensity (TCI), Weather Observations

III. SUBMISSION of QUESTIONS

From July 12, 2021 to July 26, 2021, this SBO is issued for Pre-Release. During the pre-release period, proposing firms have an opportunity to contact topic authors at osd.pentagon.ousd-r-e.mbx.hq085021s0001@mail.mil to ask technical questions about specific BAA topics.

Questions should be limited to specific information related to improving the understanding of a particular topic’s requirements. Proposing firms may not ask for advice or guidance on solution approach and may not submit additional material to the topic author. If information provided during an exchange with the topic author is deemed necessary for proposal preparation, that information will be made available to all parties through the Defense SBIR/STTR Innovation Portal (DSIP) Topic Q&A module.

Once SDA begins accepting proposals on July 27, 2021, no further direct contact between proposers and topic authors is allowed unless the topic author is responding to a question submitted during the Pre-release period. However, proposers may submit written questions through the DSIP Topic Q&A module at https://www.dodsbirsttr.mil/submissions/login. The DSIP Topic Q&A for this BAA opens on July 27, 2021 and closes to new questions on August 10, 2021 at 12 p.m. EST. Once the BAA closes to proposal submissions, no communication of any kind with the topic author or through Topic Q&A regarding a submitted proposal is allowed.

SDA intends to use electronic mail for all correspondence regarding this SBO. Questions related to the technical aspect of the research objectives and awards specifically related to this SBO should be emailed to osd.pentagon.ousd-r-e.mbx.hq085021s0001@mail.mil. Please reference SBO HQ085021S0001-12 in the subject line. All questions must be in English and must include the name, email address, and the telephone number of a point of contact.

Technical support for the DSIP is available Monday through Friday, 9:00 a.m. – 5 p.m. EST.

Requests for technical support must be emailed to DoDSBIRSupport@reisystems.com with a copy to osd.pentagon.ousd-r-e.mbx.hq085021s0001@mail.mil.