Lightweight Mirrors for Microsatellites and Small Satellites

Navy STTR 23.A - Topic N23A-T022
ONR - Office of Naval Research
Pre-release 1/11/23   Opens to accept proposals 2/08/23   Closes 3/08/23 12:00pm ET   [ View Q&A ]

N23A-T022   TITLE: Lightweight Mirrors for Microsatellites and Small Satellites

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): General Warfighting Requirements (GWR); Space

OBJECTIVE: Develop innovative manufacturing methods to produce high-quality lightweight optical mirrors for use in space on microsatellites (microsats) and small satellites (smallsats), particularly at ultraviolet (UV) and extreme ultraviolet (EUV) wavelengths.

DESCRIPTION: The Navy seeks improvements in the manufacturing of lightweight optical mirrors to meet size and weight demands of compact optical systems designed for operation in space on the next generation of microsats being designed to study the ionosphere [Refs 1, 2] and other Navy applications. Availability of high-quality lightweight optics will allow for future mission growth. The Navy seeks to foster the development of affordable optical components and systems that could have broad application to space systems. Current mirror technology involves either fragile glass optics or metal or composite mirrors that have lower optical quality. Innovative substrate materials are sought with the ruggedness, mass, and material properties necessary to produce light weight high-quality optical elements. Innovative techniques are sought to polish and figure these substrates to yield the high optical quality reflective surfaces needed for the new class of remote sensing instruments.

Typical cube satellite (CubeSat) mirrors used in smallsats have been fabricated from special aluminum alloys that are hard enough to be polished with moderate difficulty. Their density is 2.7 g/cm3, leading to significant mass penalties. The example sizes range from a fixed flat mirror (3" x 3.5" by 0.080" thick) to a scanning mirror (2" X 3.5" by 0.375" thick). Improvements are sought in the density, stiffness, polishability, roughness, figure accuracy, and moment of inertia in the scanning case. Goals are figure accuracies of λ/4 at the working wavelength, scratch/dig of 60-40, rms roughness of < 1nm, Coefficient of Thermal Expansion (CTE) compatible with typical spacecraft materials (< 4ppm/K), low outgassing (CVC < 0.1% and TML < 1%), survival at temperatures of -50 +60C, and the ability to survive a NASA GEVS3 vibration specification and thermal test environment, all typical of the requirements imposed for flight on small spacecraft.

Technologies proposed should not contain hazardous or high outgassing materials and should be capable of being integrated into typical optical systems. It is desired that they be moderately (> 10-5 O-1/m) electrically and thermally conductive (> 10W/mK) to avoid developing static charge and thermal gradients in space. They should be durable and able to withstand normal optical component handling procedures. They should be delivered in an optically clean state and be robust enough to withstand precision cleaning and vacuum baking as part of normal spacecraft processing.

PHASE I: Demonstrate the feasibility of a concept for an innovative lightweight mirror technology meeting Navy needs for microsat optical systems in the ultraviolet/vacuum ultraviolet (UV/VUV). Demonstrate performance advantages over current technology by producing small (25mm or larger) flat sample mirrors that can be tested to Navy requirements. While exact mirror dimensions are not specified for Phase I, the awardee will establish that the concept can be scaled to sizes of 100 mm diameter or larger. Phase I technology is expected to focus on the small flat mirrors that are needed to fold optical systems into compact smallsat envelopes. The path to using this technology to produce curved mirrors should be defined.

Proposed mirror concepts should meet the following thresholds:

Deliverable Design Characteristics

Value

Mirror major dimension

25mm or larger

Mirror thickness

low, < 1/6 major dimension

Substrate density

< 1 g/cm^3

Mirror flatness

< 1 wave

Mirror scratch-dig

60-40

Mirror roughness

< 1nm

Survival Temp range

-50 - +60C

Reflective Coating

for UV or VUV

Vibration, shock, and Thermal

NASA GEVS3

 

PHASE II: Develop a Phase II prototype mirror of the 100 mm size class for evaluation. The prototype will be evaluated to determine its capability in meeting the performance goals defined in Phase II Statement of Work (SoW) and the Navys need for lightweight flight mirrors. The prototype design should provide reflective areas no less than 90mm by 40mm (objective), and should show applicability to be utilized with various mirror geometries and spacecraft architectures. Deliver a minimum of five of these prototypes to the Navy for evaluation. Perform detailed analysis to ensure materials are rugged and appropriate for Navy application. Environmental, shock, and vibration analysis will be performed. Optical checks will include flatness, roughness, and reflectivity. Prototype concave mirrors of 25mm diameter and ~100mm Radius of Curvature (ROC) will be produced and evaluated.

PHASE III DUAL USE APPLICATIONS: Apply the knowledge gained in Phase II to build an advanced mirror, suitably configured for a smallsat application, including flight spares, and characterize its performance in the UV/VUV as defined by Navy requirements. Working with the Navy and applicable Industry partners, demonstrate application to a NAVY Space Test program (STP) flight test. Support the Navy for test and validation to certify and qualify the system for Navy use. Explore the potential to transfer the light weight mirror system to other military and commercial systems (NASA, University, Optics Industry).

Market research and analysis shall identify the most promising technology areas. Develop manufacturing plans to facilitate a smooth transition to the Navy.

REFERENCES:

1.       Budzien, Scott; Fritz, Bruce; Stephan, Andrew; Marquis, Peter; Powell, Steven; O'Hanlon, Brady; Nicholas, Andrew; Dymond, Kenneth and Brown, Charles. "Comparison of second and third generation 135.6 nm ionospheric photometers using on-orbit and laboratory results.", SPIE Proceedings, Volume 11131, CubeSats and SmallSats for Remote Sensing III; 1113102 (2019). https://doi.org/10.1117/12.2528791

2.       Attrill, G.D.R.et al. "Coordinated Ionospheric Reconstruction CubeSat Experiment (CIRCE), In situ and Remote Ionospheric Sensing (IRIS) suite." Journal of Space Weather and Space Climate, (2020) . J. Space Weather Clim. 11, 16, (2021). doi.org/10.1051/swsc/2020066.

3.       "NASA General Environmental Verification Standards (GEVS), Rev. A, GSFC-STD-7000 (2013)." https://standards.nasa.gov/standard/gsfc-std-7000

 

KEYWORDS: Lightweight space qualified mirrors, mirror technology, optical fabrication, spaceflight optics, spaceflight structures; microsatellites; small satellites; cube satellites

TPOC-1: Daniel Eleuterio

Email: [email protected]

 

TPOC-2: Bruce Fritz 

Email: [email protected]


** TOPIC NOTICE **

The Navy Topic above is an "unofficial" copy from the Navy Topics in the DoD 23.A STTR BAA. Please see the official DoD Topic website at www.defensesbirsttr.mil/SBIR-STTR/Opportunities/#announcements for any updates.

The DoD issued its Navy 23.A STTR Topics pre-release on January 11, 2023 which opens to receive proposals on February 8, 2023, and closes March 8, 2023 (12:00pm ET).

Direct Contact with Topic Authors: During the pre-release period (January 11, 2023 thru February 7, 2023) proposing firms have an opportunity to directly contact the Technical Point of Contact (TPOC) to ask technical questions about the specific BAA topic. Once DoD begins accepting proposals on February 8, 2023 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.

SITIS Q&A System: After the pre-release period, and until February 22, 2023, (at 12:00 PM ET), proposers may submit written questions through SITIS (SBIR/STTR Interactive Topic Information System) at www.dodsbirsttr.mil/topics-app/, login and follow instructions. In SITIS, the questioner and respondent remain anonymous but all questions and answers are posted for general viewing.

Topics Search Engine: Visit the DoD Topic Search Tool at www.dodsbirsttr.mil/topics-app/ to find topics by keyword across all DoD Components participating in this BAA.

Help: If you have general questions about the DoD SBIR/STTR program, please contact the DoD SBIR Help Desk via email at [email protected]

Topic Q & A

2/3/23  Q. The Deliverable Design Characteristic in the BAA does not show up for me, can you share those details? 
   A. Deliverable Design Characteristics     Value
Mirror major dimension     25mm or larger
Mirror thickness     low, < 1/6 major dimension
Substrate density     < 1 g/cm^3
Mirror flatness     < 1 wave
Mirror scratch-dig 60-40
Mirror roughness     < 1nm
Survival Temp range     -50 - +60C
Reflective Coating     for UV or VUV
Vibration, shock, and Thermal     NASA GEVS3

2/3/23  Q. How is flatness quantified specifically and at what wavelength light?
   A. The topic states a flatness requirement of 1 wave or better with a goal of wave. For phase 1 the requirement can be verified assuming monochromatic visible light like 633nm. When the test optic is placed against a good optical flat, fringes appear whose shape dictates the surface flatness of the optic under inspection. If the fringes are curved, the number of fringes between two imaginary lines, one tangent to the center of a fringe and one through the ends of that same fringe, indicate the flatness error.
1/26/23  Q. Are mirror surface coatings acceptable?
   A. Substrates should be polished and suitable for coating with Al/MgF2 or similar reflective coatings.
1/26/23  Q. What is the material of the mechanical component the mirror interfaces with and/or how would the mirror attach to the component?
   A. SmallSat structures are usually 6061 Al alloy etc. or composites. Maintaining figure accuracy in the operating thermal environment will determine best attachment methods.

[ Return ]