Project Selections for InVEST-20

Three Projects Awarded Under the In-Space Validation of Earth Science Technologies (InVEST) Program

6/25/2021 – NASA’s Science Mission Directorate, NASA Headquarters, Washington, DC, has selected proposals for the In-Space Validation of Earth Science Technologies Program in support of the Earth Science Division (ESD). The space environment imposes stringent conditions on components and systems, some of which cannot be fully tested on the ground or in airborne systems. Because of the harsh conditions, there has been, and continues to be, a need for new technologies to be validated in space prior to use in a science mission. The In-Space Validation of Earth Science Technologies (InVEST) program element is intended to fill that gap.

This InVEST solicitation was targeted to small instruments and instrument subsystems that can advance technology to enable relevant Earth science measurements. The call was limited to in-space validation only, and targeted to the CubeSat platform.

From a total of 13 proposals received, the ESD has selected three proposals. The total funding for these investigations is approximately $16.6 million dollars. The new InVEST awards are as follows:



The Aerosol Radiometer for Global Observation of the Stratosphere (ARGOS) Instrument
Matthew DeLand, Science Systems And Applications, Inc.

Stratospheric aerosols impact Earth’s energy budget through their direct radiative effects. The magnitude and sign of this impact is highly uncertain and variable, owing to limited knowledge of aerosol particle properties and their spatial and temporal distributions. Perturbations to the naturally occurring background stratospheric aerosol layer are caused especially by volcanic eruptions and dramatic pyrocumulonimbus injections of smoke from large wildfire/thunderstorm complexes. These events happen frequently (~several times per year), and can impact the aerosol loading and properties for months to years afterward. Although there are presently several space-borne sensors operating that observe the stratospheric aerosol layer, the particle distributions and properties remain uncertain. Dense spatial sampling of aerosol vertical profiles is required to better constrain climate model simulations of aerosol extinction, composition, and particle size, all key variables needed to estimate their short- to long-term climate impacts. Enhanced spatial and temporal sampling also improves our ability to project the short-term economic impacts of the hazards that follow volcanic and pyrocumulonimbus perturbations.

The most effective source of stratospheric aerosol extinction data comes from satellite limb scattering measurements, which provide greatly increased spatial sampling compared to occultation measurements. The Ozone Mapping and Profiling Suite (OMPS) Limb Profiler (LP) on the Suomi National Polar-orbiting Partnership (S-NPP) satellite currently provides daily aerosol extinction profile data from limb scattering measurements. While these data are a valuable resource for model studies and recent eruptions, the OMPS LP viewing geometry creates a factor of 30 difference in sensitivity to aerosol extinction between Southern Hemisphere and Northern Hemisphere observations. OMPS LP observations also have large spatial gaps between consecutive orbits.

The Aerosol Radiometer for Global Observation of the Stratosphere (ARGOS) instrument will collect limb scattering data at several wavelengths in multiple viewing directions simultaneously. Observations of the same location along the orbit track at different scattering angles will provide more balanced measurement sensitivity throughout the orbit compared to OMPS LP. These data also help constrain the aerosol phase function, and thus the particle size distribution, enabling more accurate retrieval of extinction profiles from limb scattering measurements. The multiple limb views of ARGOS provide additional sampling of the inhomogeneous aerosol field. Such denser sampling has been shown to reduce the uncertainty in model calculations of post-volcanic eruption global aerosol loading by a factor of 2-3. ARGOS uses a simplified version of the OMPS LP optical design, featuring spectral bandpass filters for wavelength selection, and a central prism to enable a compact footprint.

ARGOS is the successor to the MASTAR (Multi-Angle Stratospheric Aerosol Radiometer) instrument that has been supported by ESTO funding. MASTAR has also received significant institutional support from NASA Goddard Space Flight Center to accelerate its development. The ARGOS program will utilize the same instrument team at GSFC to develop and deliver an improved instrument within one year from program initiation. We will partner with an experienced hosted payload provider to enable ARGOS to be ready for launch on a small satellite within 6-9 months following instrument delivery. MASTAR is currently at TRL 5, and ARGOS will reach TRL 6 following completion of on-orbit testing and operations.


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ARCSTONE: Calibration of Lunar Spectral Reflectance from Space
Constantine Lukashin, NASA Langley Research Center

Calibration accuracy and long-term stability are the primary on-orbit performance metrics for all Earth observing sensors. The challenges in achieving the radiometric accuracy and stability levels over the long timescales that are needed for understanding complex systems such as Earth’s weather and climate are well recognized by the science community, both nationally and internationally. These parameters are directly connected to the measurement accuracy and scientific value of Earth observing data sets, particularly those of long duration spanning multiple spaceborne instruments. Recent research results have demonstrated the impacts of sensor radiometric accuracy on the quality of Earth Science data products and the ability to detect climate change trends for several essential climate variables. High absolute accuracy and inter-consistency of sensors are critical for a potential future constellation architecture for Earth observing systems with large numbers of instruments and platforms. ARCSTONE will provide a cross-platform means of achieving these critical performance metrics by advancing development of a high-accuracy on-orbit calibration reference for use by almost all Earth-observing instruments.

The lunar surface reflectance is extremely stable. The reflected light from the Moon can be used as a high-accuracy calibration reference that can be observed directly by most Earth observing instruments, thus enabling broad inter-calibration opportunities. While lunar calibration currently can provide sensor stability corrections at a tenth of a percent per decade, as demonstrated by SeaWIFS, the current absolute accuracy of the lunar calibration reference is limited to 5 – 10%. This is a limitation of the current lunar model (ROLO) based on ground measurements, not the Moon itself. More accurate measurements must be done from space. The ability to generate a highly accurate absolute lunar irradiance spectrum can enable precise calibration and cross-calibration of any sensors that have viewed the Moon, referenced to the same standard. High-accuracy lunar calibrations will enable transitioning to a simplified and reliable means for on-orbit calibration, thus reducing risks of data gaps and calibration errors, and potentially reducing the size, mass, and power of space-based instruments in the VSWIR (350 – 2300 nm) spectral range.

The objective of this proposal is to demonstrate in-space validation of an approach for establishing the Moon as an accurate reference for on-orbit calibration of reflected solar instruments. ARCSTONE, a hyperspectral instrument spanning the VSWIR spectral range that was designed to be integrated into a 6U CubeSat in low Earth orbit (LEO), will provide lunar spectral reflectance measurements with a target accuracy < 0.5% (k=1), sufficient to establish an absolute lunar calibration standard for past, current, and future Earth observing sensors (e.g., SeaWIFS, PACE, MODIS, VIIRS, SBG, Landsat Next, and all GEO imagers). The ARCSTONE measurement concept leverages existing NASA assets by inter-calibrating to the solar spectral irradiance observations from the TSIS/SIM, providing on-orbit SI-traceability and absolute calibration of the lunar disk reflectance. Within the 3-year time period of the proposed InVEST project, the TRL of ARCSTONE will increase from TRL5 (established by an IIP-funded and characterized instrument EDU) to TRL7, which will be achieved by flying the 6U CubeSat ARCSTONE observatory in space, collecting and validating measurements of lunar spectral reflectance, producing Level-1B data products and demonstrating their utility for improving accuracy of the current lunar calibration approach.

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Active Cooling for Methane Earth Sensors (ACMES)
Charles Swenson, Utah State University

The first technology to be validated by the ACMES mission is our Active Thermal Architectures (ATA), a complete end-to-end solution for active thermal control of cryogenic instruments on nano and small satellites. ATA consists of a two-stage cooling system with an integrated miniature tactical cryocooler forming the first stage and a micro-pumped fluid loop forming the second. Fluid is pumped between an internal heat exchanger and a radiator through a two-axis flexible rotary fluid joint. The radiator is deployed after launch and single-axis steering allows it to avoid direct solar illumination. This steerable functionality provides a 70% savings in radiator size for a given heat rejection capability. Realizing ATA was made possible through an advance 3D manufacturing process ultrasonic additive manufacturing (UAM). Using UAM, we embed the working fluid channels directly into the heat exchanger in the satellite bus, resulting in a smaller system with better thermal performance.

The second technology to be validated is the Filter Incidence Narrow-band Infrared Spectrometer (FINIS), a sensor designed for space-based detection of methane sources. FINIS uses the differential absorption technique to achieve sensitivity equivalent to larger missions such as TROPOMI, but with a much finer spatial resolution and in a compact form factor suitable for a CubeSat. FINIS uses a tilted interference filter to develop the spectrum of the methane absorption feature at 1.666 μm, but the design can be modified to other spectral regions for other target gases. Absolute radiometric calibration is not necessary–only camera flat-fielding, thereby reducing both development costs and risk on orbit. Operationally, we propose to use FINIS’ fine spatial resolution to pinpoint and quantify localized methane sources, guided to specific regions of interest by TROPOMI observations.

ATA and FINIS are each currently at TRL 6 and 5+, respectively. By demonstrating them on ACMES we will raise the TRL of both systems to 7. It is important to note that each is an independent technology — FINIS can meet requirements without ATA, and ATA can operate and be validated alone, but the combination enables greater operational capability for FINIS and demonstrates a realistic and practical implementation of ATA to cool a miniature electro-optical sensor on a CubeSat bus. Thus, the ACMES mission will demonstrate and validate two significant technological innovations for the next generation of space-based Earth science observations.

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