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Summary of the 10th DSCOVR EPIC and NISTAR Science Team Meeting
Introduction
The 10th Deep Space Climate Observatory (DSCOVR) Earth Polychromatic Camera (EPIC) and National Institute of Standards and Technology (NIST) Advanced Radiometer [NISTAR] Science Team Meeting (STM) was held October 16–18, 2024. Over 50 scientists attended, most of whom were from NASA’s Goddard Space Flight Center (GSFC), with several participating from other NASA centers, U.S. universities, and U.S. Department of Energy laboratories. There was one international participant – from Estonia. A full overview of DSCOVR’s Earth-observing instruments was published in a previous article in The Earth Observer and will not be repeated here. This article provides the highlights of the 2024 meeting. The meeting agenda and full presentations can be downloaded from GSFC’s Aura Validation Data Center.
Opening Presentations
The opening session of the 10th DSCOVR STM was special. Former U.S., Vice President Al Gore attended the opening session and gave a presentation at the panel discussion “Remote Sensing and the Future of Earth Observations” – see Photo. Gore was involved in the early days of planning the DSCOVR mission, which at that time was known as Triana. He reminisced about his involvement and praised the team for the work they’ve done over the past decade to launch and maintain the DSCOVR mission. Following the STM Opening Session, Gore spoke at a GSFC Engage session in Building 3 later that afternoon on the same topic, but before a wider audience. [Link forthcoming.]
Following Gore’s remarks, the remainder of the opening session consisted of a series of presentations from DSCOVR mission leaders and representatives from GSFC and National Oceanic and Atmospheric Administration (NOAA). Thomas Neumann [GSFC, Earth Sciences Division (ESD)—Deputy Director] opened the meeting and welcomed Vice President Gore and the STM participants on behalf of the ESD. Adam Szabo [GSFC—DSCOVR Project Scientist] briefly reported that the spacecraft was still in “good health.” The EPIC and NISTAR instruments on DSCOVR continue to return their full science observations. He also gave an update on DSCOVR Space Weather research. Alexander Marshak [GSFC—DSCOVR Deputy Project Scientist] briefly described DSCOVR mission history and the science results based on DSCOVR observations from the first Sun–Earth Lagrange point (hereinafter, the L1 point). He also summarized the major EPIC and NISTAR results to date. At this time, more than 125 papers related to DSCOVR are listed on the EPIC website. Elsayed Talaat [NOAA, Office of Space Weather observations—Director] discussed the future of Earth and space science studies from the L1 point.
Photo. Former U.S. Vice President Al Gore spoke at the opening session of the 10th DSCOVR Science Team Meeting. This photo shows Gore together with Makenzie Lystrup [NASA’s Goddard Space Flight Center (GSFC)—Center Director], Christa Peters-Lidard [GSFC, Director of the Science and Exploration Directorate], Elsayed Talaat [National Oceanic and Atmospheric Administration (NOAA)—Director of the Office of Space Weather Observations], Dalia Kirschbaum [GSFC—Director of Earth Sciences], other GSFC management, and members of the DSCOVR Science Team. Photo credit: Katy Comber (GSFC) Updates on DSCOVR Operations
The DSCOVR mission components continue to function nominally. The meeting was an opportunity to update participants on progress over the past year on several fronts, including data acquisition, processing, and archiving, and release of new versions of several data products. The number of people using DSCOVR data continues to increase, with a new Science Outreach Team having been put in place to aid users in several aspects of data discovery, access, and user friendliness.
Amanda Raab [NOAA, DSCOVR Mission Operations and Systems] reported on the current status of the DSCOVR mission. She also discussed spacecraft risks and issues such as memory fragmentation and data storage task anomalies but indicated that both these issues have been resolved.
Hazem Mahmoud [NASA’s Langley Research Center (LaRC)] discussed the work of the Atmospheric Science Data Center (ASDC), which is based at LaRC. He showed DSCOVR mission metrics since 2015, focusing on data downloads and the global outreach of the mission. He noted that there has been a significant rise in the number of downloads and an increasing diversity of countries accessing ozone (O3), aerosol, and cloud data products. Mahmoud also announced that the ASDC is transitioning to the Amazon Web Services cloud, which will further enhance global access and streamline DSCOVR data processing.
Karin Blank [GSFC] covered the discovery of a new type of mirage that can only be seen in deep space from EPIC. The discussion included the use of a ray tracer in determining the origin of the phenomenon, and under what conditions it can be seen.
Alexander Cede [SciGlob] and Ragi Rajagopalan [LiftBlick OG] gave an overview of the stability of the EPIC Level-1A (L1A) data over the first decade of operation. They explained that the only observable changes in the EPIC calibration are to the dark count and flat field can – and that these changes can be entirely attributed to the temperature change of the system in orbit compared to prelaunch conditions. No additional hot or warm pixels have emerged since launch and no significant sensitivity drifts have been observed. The results that Cede and Rajagopalan showed that EPIC continues to be a remarkably stable instrument, which is attributed to a large extent to its orbit around the L1 point, which is located outside the Earth’s radiation belts and thus an extremely stable temperature environment. Consequently, in terms of stability, the L1 point is far superior to other Earth observation points, e.g., ground-based, low-Earth orbit (LEO), polar orbit, or geostationary Earth orbit (GEO).
Marshall Sutton [GSFC] discussed the state of the DSCOVR Science Operation Center (DSOC). He also talked about processing EPIC Level-1 (L1) data into L2 science products, daily images available on the EPIC website, and special imaging opportunities, e.g., volcanic eruptions.
EPIC Calibration
After 10 years of operation in space, the EPIC instrument on DSCOVR continues to be a remarkably stable instrument. The three presentations describe different ways that are used to verify the EPIC measurements remain reliable.
Conor Haney [LaRC] reported on anomalous outliers during February and March 2023 from the broadband shortwave (SW) flux using EPIC L1B channel radiances. To ensure that these outliers were not a result of fluctuations in the EPIC L1B channel radiances, both the EPIC radiance measurements and coincident, ray-matched radiance measurements from the Visible Infrared Imaging Radiometer Suite (VIIRS), on the Suomi National Polar-orbiting Partnership (Suomi NPP) platform, were processed using the same deep convective cloud invariant target (DCC-IT) algorithm. This analysis confirmed that the anomalous behavior was due to the DCC-IT algorithm – and not because of fluctuations in the EPIC L1B channel radiances. The improved DCC-IT methodology was also applied to the EPIC L1B radiances. The results indicate that the EPIC record is quite stable with a lower uncertainty than when processed using the previous DCC-IT methodology.
Igor Geogdzhaev [NASA’s Goddard Institute for Space Studies (GISS)/Columbia University] reported that EPIC Visible–Near Infrared (VIS-NIR) calibration based on VIIRS (on Suomi NPP) data has showed excellent stability, while VIIRS (on NOAA-20 and -21) derived gains agree to within 1–2%. Preliminary analysis showed continuity in the gains derived from Advanced Baseline Imager (ABI) data. (ABI flies on NOAA’s two operational Geostationary Operational Environmental Satellite–Series R satellites – GOES-17 and GOES-18.
Liang–Kang Huang [Science Systems and Applications, Inc. (SSAI)] reported on updates to the EPIC ultraviolet (UV) channel sensitivity time dependences using Sun-normalized radiance comparisons between EPIC and measurements from the Ozone Mapping and Profiler Suite (OMPS) Nadir Mapper (NM) on Suomi NPP, with coinciding footprints and solar/satellite angles. Huang’s team determined vignetting factors in the sensitivity calibration between 2021–2024, as a function of charge coupled device (CCD) pixel radius and pixel polar angles, using special lunar measurement sequences.
NISTAR Status and Science with Its Observations
The NISTAR instrument remains fully functional and continues its uninterrupted data record. The NISTAR-related presentations during this meeting included more details on specific topics related to NISTAR as well as on efforts to combine information from both EPIC and NISTAR.
Steven Lorentz [L-1 Standards and Technology, Inc.] reported that the NISTAR on DSCOVR has been measuring the irradiance from the sunlit Earth in three bands for more than nine years. The three bands measure the outgoing total and reflected-solar radiation from Earth at a limited range of solar angles. To compare the long-term stability of EPIC and NISTAR responses, researchers developed a narrowband to wideband conversion model to allow the direct comparison of the EPIC multiband imagery and NISTAR SW – see Figure 1 – and silicon photodiode channels. Lorentz presented daily results spanning several years. The comparison employed different detectors from the same spacecraft – but with the same vantage point – thereby avoiding any model dependent orbital artifacts.
Figure 1. NISTAR daily average shortwave (SW) radiance plotted for each year from 2017–2024. The results indicated a 10% increase in the shortwave radiance as the backscattering angle approaches 178° in December 2020. A 6% increase is noted in September of the same year. Figure credit: Steven Lorentz (L-1 Standards and Technology) Clark Weaver [University of Maryland, College Park (UMD)] used spectral information from the SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY), which flew on the European Space Agency’s (ESA) Envisat satellite from 2002–2012, to fill EPIC spectral gaps. He reported on construction of a composite height resolution spectrum that was spectrally integrated to produce SW energy. Weaver explained that he compared the EPIC reflected SW with four-hour averages from Band 4 on NISTAR. He used spectral information from SCIAMACHY to fill in gaps. Weaver also discussed results of a comparison of area integrated EPIC SW energy with observations from NISTAR .
Andrew Lacis [GISS] reported on results of analysis of seven years of EPIC-derived planetary albedo for Earth, which reveal global-scale longitudinal variability occurring over a wide range of frequencies – with strong correlation between nearby longitudes and strong anticorrelation between diametrically opposed longitudes. This behavior in the Earth’s global-scale energy budget variability is fully corroborated by seven years of NISTAR silicon photodiode measurements, which view the Earth with 1º longitudinal resolution. This analysis establishes the DSCOVR mission EPIC/NISTAR measurements as a new and unmatched observational data source for evaluating global climate model performance– e.g., see Figure 2.
Figure 2. This graph shows the diurnal variation in planetary albedo as measured by EPIC for five different eight-day-Blurred Meridians relative to Global Mean for 2021 [left] and 2022 [right]. Figure credit: Andrew Lacis [GISS] Wenying Su [LaRC] discussed global daytime mean SW fluxes within the EPIC field of view produced from January 2016–June 2024. These quasi-hourly SW fluxes agree very well with the Synoptic data product from the Clouds and the Earth’s Radiant Energy System (CERES) instruments (currently flying on the Terra and Aqua, Suomi NPP, and NOAA-20 platforms) with the root mean square errors (rmse) less than 3 W/m2. This SW flux processing framework will be used to calculate NISTAR SW flux when Version 4 (V4) of the NISTAR radiance becomes available. Su noted that SW fluxes from EPIC are not suitable to study interannual variability as the magnitude of EPIC flux is sensitive to the percentage of daytime area visible to EPIC.
Update on EPIC Products and Science Results
EPIC has a suite of data products available. The following subsections summarize content during the DSCOVR STM related to these products. The updates focus on several data products and the related algorithm improvements.
Total Column Ozone
Jerry Ziemke [Morgan State University (MSU), Goddard Earth Sciences Technology and Research–II (GESTAR II)] and Natalya Kramarova [GSFC] reported that tropospheric O3 from DSCOVR EPIC shows anomalous reductions of ~10% throughout the Northern Hemisphere (NH) starting in Spring 2020 that continues to the present. The EPIC data, along with other satellite-based (e.g., Ozone Monitoring Instrument (OMI) on NASA’s Aura platform) and ground-based (e.g., Pandora) data, indicate that the observed NH reductions in O3 are due to combined effects from meteorology and reduced pollution, including reduced shipping pollution in early 2020 (during COVID) – see Figure 3. EPIC 1–2 hourly data are also used to evaluate hourly total O3 and derived tropospheric O3 from NASA’s Tropospheric Emissions: Monitoring of Pollution (TEMPO) geostationary instrument. Ziemke explained that comparison of TEMPO data with EPIC data has helped the researchers characterize a persistent latitude-dependent offset in TEMPO total O3 data of ~10–15% from south to north over the North American continent.
Figure 3. This dataset combines input from EPIC, OMPS, and OMI from 2004–2022. The onset of the COVID-19 pandemic in 2020 can be seen clearly in the data as it corresponds to a sudden drop in tropospheric column ozone by ~3 Dobson Units in the Northern Hemisphere. Figure credit: Jerry Ziemke (Morgan State University, GESTAR-II) Algorithm Improvement for Ozone and Sulfur Dioxide Products
Kai Yang [UMD] presented a comprehensive evaluation of total and tropospheric O3 retrievals, highlighting the long-term stability and high accuracy of EPIC measurements. He also validated EPIC’s volcanic sulfur dioxide (SO2) retrievals by comparing them with ground-based Brewer spectrophotometer measurements and summarized EPIC’s observations of SO2 from recent volcanic eruptions.
Simon Carn [University of Michigan] showed the first comparisons between the EPIC L2 volcanic SO2 product and SO2 retrievals from the Geostationary Environment Monitoring Spectrometer (GEMS) on the Korean GEO-Kompsat-2B satellite. GEMS observes East Asia as part of the new geostationary UV air quality (GEO-AQ) satellite constellation (which also includes TEMPO that observes North America and will include the Ultraviolet–Visible–Near Infrared (UVN) instrument on the European Copernicus Sentinel-4 mission, that will be launched in 2025 to observe Europe and surrounding areas) – but is not optimized for measurements of high SO2 columns during volcanic eruptions. EPIC SO2 data for the 2024 eruption of Ruang volcano in Indonesia are being used to validate a new GEMS volcanic SO2 product. Initial comparisons show good agreement between EPIC and GEMS before volcanic cloud dispersal and confirm the greater sensitivity of the hyperspectral GEMS instrument to low SO2 column amounts.
Aerosols
Alexei Lyapustin [GSFC] reported that the latest EPIC aerosols algorithm (V3) simultaneously retrieves aerosol optical depth, aerosol spectral absorption, and aerosol layer height (ALH) – achieving high accuracy. He showed that global validation of the single scattering albedo in the blue and red shows 66% and 81–95% agreement respectively, with Aerosol Robotic Network (AERONET) observations – which is within the expected error of 0.03 for smoke and dust aerosols. Lyapustin also reported on a comparison of EPIC aerosol data collected from 2015–2023 by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), which flew on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission. The results show that ALH is retrieved with rmse ~1.1 km (0.7 mi). ALH is unbiased over the ocean and is underestimated by 450 m (1470 ft) for the smoke and by 750 m (2460 ft) for the dust aerosols over land.
Myungje Choi and Sujung Go [both from University of Maryland, Baltimore County’s (UMBC), GESTAR II] presented results from a global smoke and dust characterization using Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm. This study characterized smoke and dust aerosol properties derived from MAIAC EPIC processing, examining spectral absorption, ALH, and chemical composition (e.g., black and brown carbon). Regions with smoldering wildfires, e.g., North America and Siberia, exhibited high ALH and a significant fraction of brown carbon, while Central Africa showed lower ALH with higher black carbon emissions.
Omar Torres [GSFC] discussed how L1 DSCOVR-EPIC observations are being used to study air quality (i.e., tropospheric O3 and aerosols) globally. Torres noted that this application of EPIC-L1 observations is of particular interest in the Southern Hemisphere (SH) where, unlike over the NH, there are currently no space GEO-based air quality measurements – and no plans for them in the foreseeable future.
Hiren Jethva [MSU, GESTAR II] presented the new results of the aerosol optical centroid height retrieved from the EPIC Oxygen-B band observations. He described the algorithm details, showed retrieval maps, and reviewed the comparative analysis against CALIOP backscatter-weighted measurements. The analysis showed a good level of agreement with more than 70% of matchup data within 1–1.5 km (0.6–0.9 mi) difference.
Jun Wang [University of Iowa] presented his team’s work on advancing the second generation of the aerosol optical centroid height (AOCH) algorithm for EPIC. Key advancements included: constraining surface reflectance in aerosol retrieval using an EPIC-based climatology of surface reflectance ratios between 442–680 nm; incorporating a dynamic aerosol model to characterize aged smoke particles; and employing a spectral slope technique to distinguish thick smoke plumes from clouds. Results show that both atmospheric optical depth (AOD) and AOCH retrievals are improved in the second generation of AOCH algorithm.
Olga Kalashnikova [NASA/Jet Propulsion Laboratory (JPL)] reported on improving brown carbon evolution processes in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) model with EPIC products. She indicated that DSCOVR product evaluation, using lidar aerosol height measurements from CALIOP, led to an improved operational brown carbon product. To better resolve the temporal evolution of brown carbon, chemical transport models need to include more information about near-source fires.
Mike Garay [NASA/Jet Propulsion Laboratory (JPL)] discussed constraining near-source brown carbon emissions from 2024 Canadian ‘zombie’ fires with EPIC products. He reported that fires in British Columbia, Canada showed differences in brown carbon emission near the sources. Garay explained that their investigation has revealed that these differences were related to fire intensity and variations in vegetation/soil content.
Yuekui Yang [GSFC] presented work that examined the impact of Earth’s curvature consideration on EPIC cloud height retrievals. Biases under the Plane Parallel (PPL) assumption is studied by comparing results using the improved pseudo-spherical shell approximation. PPL retrievals in general bias high and for a cloud with height of 5 km (3 mi), the bias is about 6%.
Alfonso Delgado Bonal [UMBC] stated that the EPIC vantage point offers a unique opportunity to observe not only the current state of the Earth but also its temporal evolution. By capturing multiple observations of the planet throughout the day, EPIC enables statistical reconstruction of diurnal patterns in clouds and other atmospheric parameters. Bonal’s team focused their research on O3 (primarily tropospheric) over the U.S. to demonstrate the presence of a diurnal cycle in the western regions of the continental U.S. However, ground-based data from PANDORA for specific locations do not support these diurnal variations – underscoring the critical role of space-based O3 retrievals. The proposed methodology is not limited to clouds or O3 but is broadly applicable to other EPIC measurements for the dynamic nature of our planet.
Elizabeth Berry [Atmospheric and Environmental Research (AER)] presented results from a coincident DSCOVR–CloudSat dataset [covering 2015–2020]. Cloud properties (e.g., cloud height and optical depth) from DSCOVR and CloudSat are moderately correlated and show quite good agreement given differences in the instruments sensitivities and footprints. Berry explained that a machine-learning model trained on the coincident data demonstrates high accuracy at predicting the presence of vertical cloud layers. However, precision and recall metrics highlight the challenge of predicting the precise location of cloud boundaries.
Anthony Davis [JPL] presented a pathway toward accurate estimation of the cloud optical thickness (COT) of opaque clouds and cloud systems, e.g., supercells, mesoscale convective complexes, and tropical cyclones (TCs). He described the approach, which uses differential oxygen absorption spectroscopy (DOAS) that has resolving power greater than 104 – which is comparable to that of the high-resolution spectrometers on NASA’s Orbiting Carbon Observatory–2 (OCO-2) – but is based upon the cloud information content of EPIC’s O2 A- and B-band radiances. Unlike the current operational retrieval of COT – which uses data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua – the DOAS-based technique does not saturate at COT exceeding ~60. According to a popular TC model with two-moment microphysics, COT in a tropical storm or hurricane can reach well into the hundreds, sometimes exceeding 1000. Davis said that once the new COT estimates become available, they will provide new observational constraints on process and forecast models for TCs.
Ocean
Robert Frouin [Scripps Institution of Oceanography, University of California] discussed ocean surface radiation products derived from EPIC data. He explained that significant advancements have been achieved in processing and evaluating ocean biology and biogeochemistry products derived from EPIC imagery. V1 updates enhanced accuracy by integrating Modern-Era Retrospective analysis for Research and Applications V2 (MERRA-2) ancillary data and refining calculations for atmospheric and surface parameters. Frouin introduced several diurnal products, including hourly photosynthetically active radiation (PAR) fluxes, spectral water reflectance, and chlorophyll-a concentrations. He said that these new MODIS-derived products have been validated through comparisons with data from the Advanced Himawari Imager on the Japanese Himawar–8 and –9 satellites. In order to address the gaps in these diurnal products, Frouin explained that the team developed a convolutional neural network that has been used effectively to reconstruct missing PAR values with high accuracy.
Vegetation
Yuri Knyazikhin [Boston University] reported on the status of the Vegetation Earth System Data Record (VESDR) that provides a variety of parameters including: Leaf Area Index (LAI), diurnal courses of Normalized Difference Vegetation Index (NDVI), Sunlit LAI (SLAI), Fraction of incident Photosynthetically Active Radiation (FPAR) absorbed by the vegetation, Directional Area Scattering Function (DASF), Earth Reflector Type Index (ERTI), and Canopy Scattering Coefficient (CSC). Knyazikhin discussed analysis of the diurnal and seasonal variations of these quantities. EPIC LAI and FPAR are consistent with MODIS-derived measurements of the same parameters.
Jan Pisek [University of Tartu/Tartu Observatory, Estonia] discussed efforts to derive leaf inclination information from EPIC data. The very first evaluation over Tumbarumba site (in New South Wales, Australia) showed that the angular variation in parameters obtained from EPIC reflects the expected variations due to the erectophile vegetation present at the site.
Sun Glint
Tamás Várnai [UMBC, JCET] discussed EPIC observations of Sun glint from ice clouds. The cloud glints come mostly from horizontally oriented ice crystals and have strong impact in EPIC cloud retrievals. Várnai reported that the EPIC glint product is available from the ASDC – see Figure 4. Glint data can help reduce the uncertainties related to horizontally oriented ice crystals and yield additional new insights about the microphysical and radiative properties of ice clouds.
Figure 4. [top row] EPIC glint mask examples over land in [left to right] Paraguay, Sudan, Thailand, and Brazil. [bottom row] The corresponding EPIC glint mask for each image on the top row indicates the band (red, green and blue) and the size of sun glint for each of them. Figure credit: Tamás Várnai (University of Maryland, Baltimore County) Alexander Kostinski [Michigan Technology University] explained that because they detected climatic signals (i.e., longer-term changes and semi-permanent features, e.g., ocean glitter), they developed a technique to suppress geographic “noise” in EPIC images that involves introducing temporally (monthly) and conditionally (classifying by surface/cover type, e.g., land, ocean, clouds) averaged reflectance images – see Figure 5. The resulting images display seasonal dependence in a striking manner. Additionally, cloud-free, ocean-only images highlight prominent regions of ocean glitter.
Figure 5. Monthly reflectances for clear land pixels. Earth masquerading as Jupiter; latitudinal bright bands are caused by features such as the Sahara and Antarctica. Black spots are due to the lack or dearth of clear land pixels at that latitude. Repeated spots within latitudinal bands reflect roughly bi-hourly image sampling. Figure credit: Alexander Kostinski (Michigan Technology University); from a 2024 paper published in Frontiers of Remote Sensing Jiani Yang [Caltech] reported that spatially resolving light curves from DSCOVR is crucial for evaluating time-varying surface features and the presence of an atmosphere. Both of these features are essential for sustaining life on Earth – and thus can be used to assess the potential habitability of exoplanets. Using epsilon machine reconstruction, the statistical complexity from the time series data of these light curves can be calculated. The results show that statistical complexity serves as a reliable metric for quantifying the intricacy of planetary features. Higher levels of planetary complexity qualitatively correspond to increased statistical complexity and Shannon entropy, illustrating the effectiveness of this approach in identifying planets with the most dynamic characteristics.
Other EPIC Science Results
Guoyong Wen [MSU, GESTAR II] analyzed the variability of global spectral reflectance from EPIC and the integrated broadband reflectance on different timescales. He reported that on a diurnal timescale, the global reflectance variations in UV and blue bands are statistically similar – and drastically different from those observed in longer wavelength bands (i.e., green to NIR). The researchers also did an analysis of monthly average results and found that temporal averaging of the global reflectance reduces the variability across the wavelength and that the variability of broadband reflectance is similar to that for the red band on both timescales. These results are mainly due to the rotation of the Earth on diurnal timescale and the change of the Earth’s tilt angle.
Nick Gorkavyi [Science Systems and Applications, Inc. (SSAI)] reported that EPIC – located at the L1 point, 1.5 million km (0.9 million mi) away from Earth – can capture images of the far side of the Moon in multiple wavelengths. These images, taken under full solar illumination, can be used to calibrate photographs obtained by lunar artificial satellites. Additionally, he discussed the impact of lunar libration – the changing view of the Moon from Earth, or it’s apparent “wobble” – on Earth observations from the Moon.
Jay Herman [UMBC] discussed a comparison of EPIC O3 with TEMPO satellite and Pandora ground-based measurement. The results show that total column O3 does not have a significant photochemical diurnal variation. Instead, the daily observed diurnal variation is caused by weather changes in atmospheric pressure. This measurement result agrees with model calculations.
Conclusion
Alexander Marshak, Jay Herman, and Adam Szabo led a closing discussion with ST participants on how to make the EPIC and NISTAR instruments more visible in the community. It was noted that the EPIC website now allows visitors to observe daily fluctuations of aerosol index, cloud fraction, cloud height, and the ocean surface – as observed from the L1 point. More daily products, (e.g., aerosol height and sunlit leaf area index) will be added soon, which should attract more users to the website.
Overall, the 2023 DSCOVR EPIC and NISTAR STM was successful. It provided an opportunity for participants to learn the status of DSCOVR’s Earth-observing instruments, EPIC and NISTAR, the status of recently released L2 data products, and the science results being achieved from the L1 point. As more people use DSCOVR data worldwide, the ST hopes to hear from users and team members at its next meeting. The latest updates from the mission can be found on the EPIC website.
Alexander Marshak
NASA’s Goddard Space Flight Center
alexander.marshak@nasa.gov
Adam Szabo
NASA’s Goddard Space Flight Center
adam.szabo@nasa.gov
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Last Updated Feb 14, 2025 Related Terms
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By NASA
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Preparations for Next Moonwalk Simulations Underway (and Underwater)
A team at JPL packed up three small Moon rovers, delivering them in February to the facility where they’ll be attached to a commercial lunar lander in preparation for launch. The rovers are part of a project called CADRE that could pave the way for potential future multirobot missions.. NASA/JPL-Caltech A trio of suitcase-size rovers and their base station have been carefully wrapped up and shipped off to join the lander that will deliver them to the Moon’s surface.
Three small NASA rovers that will explore the lunar surface as a team have been packed up and shipped from the agency’s Jet Propulsion Laboratory in Southern California, marking completion of the first leg of the robots’ journey to the Moon.
The rovers are part of a technology demonstration called CADRE (Cooperative Autonomous Distributed Robotic Exploration), which aims to show that a group of robots can collaborate to gather data without receiving direct commands from mission controllers on Earth. They’ll use their cameras and ground-penetrating radars to send back imagery of the lunar surface and subsurface while testing out the novel software that enables them to work together autonomously.
The CADRE rovers will launch to the Moon aboard IM-3, Intuitive Machines’ third lunar delivery, which has a mission window that extends into early 2026, as part of NASA’s CLPS (Commercial Lunar Payload Services) initiative. Once installed on Intuitive Machines’ Nova-C lander, they’ll head to the Reiner Gamma region on the western edge of the Moon’s near side, where the solar-powered, suitcase-size rovers will spend the daylight hours of a lunar day (the equivalent of about 14 days on Earth) carrying out experiments. The success of CADRE could pave the way for potential future missions with teams of autonomous robots supporting astronauts and spreading out to take simultaneous, distributed scientific measurements.
Members of a JPL team working on NASA’s CADRE technology demonstration use temporary red handles to move one of the project’s small Moon rovers to prepare it for transport to Intuitive Machines’ Houston facility, where it will be attached to the company’s third lunar lander. Construction of the CADRE hardware — along with a battery of rigorous tests to prove readiness for the journey through space — was completed in February 2024.
To get prepared for shipment to Intuitive Machines’ Houston facility, each rover was attached to its deployer system, which will lower it via tether from the lander onto the dusty lunar surface. Engineers flipped each rover-deployer pair over and attached it to an aluminum plate for safe transit. The rovers were then sealed in protective metal-frame enclosures that were fitted snuggly into metal shipping containers and loaded onto a truck. The hardware arrived safely on Sunday, Feb. 9.
“Our small team worked incredibly hard constructing these robots and putting them to the test, and we have been eagerly waiting for the moment where we finally see them on their way,” said Coleman Richdale, the team’s assembly, test, and launch operations lead at JPL. “We are all genuinely thrilled to be taking this next step in our journey to the Moon, and we can’t wait to see the lunar surface through CADRE’s eyes.”
The rovers, the base station, and a camera system that will monitor CADRE experiments on the Moon will be integrated with the lander — as will several other NASA payloads — in preparation for the launch of the IM-3 mission.
More About CADRE
A division of Caltech in Pasadena, California, JPL manages CADRE for the Game Changing Development program within NASA’s Space Technology Mission Directorate. The technology demonstration was selected under the agency’s Lunar Surface Innovation Initiative, which was established to expedite the development of technologies for sustained presence on the lunar surface. NASA’s Science Mission Directorate manages the CLPS initiative. The agency’s Glenn Research Center in Cleveland and its Ames Research Center in Silicon Valley, California, both supported the project. Motiv Space Systems designed and built key hardware elements at the company’s Pasadena facility. Clemson University in South Carolina contributed research in support of the project.
For more about CADRE, go to:
https://go.nasa.gov/cadre
News Media Contact
Melissa Pamer
Jet Propulsion Laboratory, Pasadena, Calif.
626-314-4928
melissa.pamer@jpl.nasa.gov
2025-018
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Last Updated Feb 11, 2025 Related Terms
CADRE (Cooperative Autonomous Distributed Robotic Exploration) Commercial Lunar Payload Services (CLPS) Earth's Moon Game Changing Development Program Jet Propulsion Laboratory Space Technology Mission Directorate Technology Technology Demonstration Explore More
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Preparations for Next Moonwalk Simulations Underway (and Underwater)
Jeremy Frank, left, and Caleb Adams, right, discuss software developed by NASA’s Distributed Spacecraft Autonomy project. The software runs on spacecraft computers, currently housed on a test rack at NASA’s Ames Research Center in California’s Silicon Valley, and depicts a spacecraft swarm virtually flying in lunar orbit to provide autonomous position navigation and timing services at the Moon. NASA/Brandon Torres Navarrete Talk amongst yourselves, get on the same page, and work together to get the job done! This “pep talk” roughly describes how new NASA technology works within satellite swarms. This technology, called Distributed Spacecraft Autonomy (DSA), allows individual spacecraft to make independent decisions while collaborating with each other to achieve common goals – all without human input.
NASA researchers have achieved multiple firsts in tests of such swarm technology as part of the agency’s DSA project. Managed at NASA’s Ames Research Center in California’s Silicon Valley, the DSA project develops software tools critical for future autonomous, distributed, and intelligent swarms that will need to interact with each other to achieve complex mission objectives.
“The Distributed Spacecraft Autonomy technology is very unique,” said Caleb Adams, DSA project manager at NASA Ames. “The software provides the satellite swarm with the science objective and the ‘smarts’ to get it done.”
What Are Distributed Space Missions?
Distributed space missions rely on interactions between multiple spacecraft to achieve mission goals. Such missions can deliver better data to researchers and ensure continuous availability of critical spacecraft systems.
Typically, spacecraft in swarms are individually commanded and controlled by mission operators on the ground. As the number of spacecraft and the complexity of their tasks increase to meet new constellation mission designs, “hands-on” management of individual spacecraft becomes unfeasible.
Distributing autonomy across a group of interacting spacecraft allows for all spacecraft in a swarm to make decisions and is resistant to individual spacecraft failures.
The DSA team advanced swarm technology through two main efforts: the development of software for small spacecraft that was demonstrated in space during NASA’s Starling mission, which involved four CubeSat satellites operating as a swarm to test autonomous collaboration and operation with minimal human operation, and a scalability study of a simulated spacecraft swarm in a virtual lunar orbit.
Experimenting With DSA in Low Earth Orbit
The team gave Starling a challenging job: a fast-paced study of Earth’s ionosphere – where Earth’s atmosphere meets space – to show the swarm’s ability to collaborate and optimize science observations. The swarm decided what science to do on their own with no pre-programmed science observations from ground operators.
“We did not tell the spacecraft how to do their science,” said Adams. “The DSA team figured out what science Starling did only after the experiment was completed. That has never been done before and it’s very exciting!”
The accomplishments of DSA onboard Starling include the first fully distributed autonomous operation of multiple spacecraft, the first use of space-to-space communications to autonomously share status information between multiple spacecraft, the first demonstration of fully distributed reactive operations onboard multiple spacecraft, the first use of a general-purpose automated reasoning system onboard a spacecraft, and the first use of fully distributed automated planning onboard multiple spacecraft.
During the demonstration, which took place between August 2023 and May 2024, Starling’s swarm of spacecraft received GPS signals that pass through the ionosphere and reveal interesting – often fleeting – features for the swarm to focus on. Because the spacecraft constantly change position relative to each other, the GPS satellites, and the ionospheric environment, they needed to exchange information rapidly to stay on task.
Each Starling satellite analyzed and acted on its best results individually. When new information reached each spacecraft, new observation and action plans were analyzed, continuously enabling the swarm to adapt quickly to changing situations.
“Reaching the project goal of demonstrating the first fully autonomous distributed space mission was made possible by the DSA team’s development of distributed autonomy software that allowed the spacecraft to work together seamlessly,” Adams continued.
Caleb Adams, Distributed Spacecraft Autonomy project manager, monitors testing alongside the test racks containing 100 spacecraft computers at NASA’s Ames Research Center in California’s Silicon Valley. The DSA project develops and demonstrates software to enhance multi-spacecraft mission adaptability, efficiently allocate tasks between spacecraft using ad-hoc networking, and enable human-swarm commanding of distributed space missions. NASA/Brandon Torres Navarrete Scaling Up Swarms in Virtual Lunar Orbit
The DSA ground-based scalability study was a simulation that placed virtual small spacecraft and rack-mounted small spacecraft flight computers in virtual lunar orbit. This simulation was designed to test the swarm’s ability to provide position, navigation, and timing services at the Moon. Similar to what the GPS system does on Earth, this technology could equip missions to the Moon with affordable navigation capabilities, and could one day help pinpoint the location of objects or astronauts on the lunar surface.
The DSA lunar Position, Navigation, and Timing study demonstrated scalability of the swarm in a simulated environment. Over a two-year period, the team ran close to one hundred tests of more complex coordination between multiple spacecraft computers in both low- and high-altitude lunar orbit and showed that a swarm of up to 60 spacecraft is feasible.
The team is further developing DSA’s capabilities to allow mission operators to interact with even larger swarms – hundreds of spacecraft – as a single entity.
Distributed Spacecraft Autonomy’s accomplishments mark a significant milestone in advancing autonomous distributed space systems that will make new types of science and exploration possible.
NASA Ames leads the Distributed Spacecraft Autonomy and Starling projects. NASA’s Game Changing Development program within the agency’s Space Technology Mission Directorate provides funding for the DSA experiment. NASA’s Small Spacecraft Technology program within the Space Technology Mission Directorate funds and manages the Starling mission and the DSA project.
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Last Updated Feb 04, 2025 Related Terms
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By NASA
3 min read
NASA’s Cloud-based Confluence Software Helps Hydrologists Study Rivers on a Global Scale
The Paraná River in northern Argentina. Confluence, which is open-source and free to use, allows researchers to estimate river discharge and suspended sediment levels in Earth’s rivers at a global scale. NASA/ISS Rivers and streams wrap around Earth in complex networks millions of miles long, driving trade, nurturing ecosystems, and stocking critical reserves of freshwater.
But the hydrologists who dedicate their professional lives to studying this immense web of waterways do so with a relatively limited set of tools. Around the world, a patchwork of just 3,000 or so river gauge stations supply regular, reliable data, making it difficult for hydrologists to detect global trends.
“The best way to study a river,” said Colin Gleason, Armstrong Professional Development Professor of Civil and Environmental Engineering at the University of Massachusetts, Amherst, “is to get your feet wet and visit it yourself. The second best way to study a river is to use a river gauge.”
Now, thanks to Gleason and a team of more than 30 researchers, there’s another option: ‘Confluence,’ an analytic collaborative framework that leverages data from NASA’s Surface Water and Ocean Topography (SWOT) mission and the Harmonized Landsat Sentinel-2 archive (HLS) to estimate river discharge and suspended sediment levels in every river on Earth wider than 50 meters. NASA’s Physical Oceanography Distributed Active Archive Center (PO.DAAC) hosts the software, making it open-source and free for users around the world.
By incorporating both altimetry data from SWOT which informs discharge estimates, and optical data from HLS, which informs estimates of suspended sediment data, Confluence marks the first time hydrologists can create timely models of river size and water quality at a global scale. Compared to existing workflows for estimating suspended sediment using HLS data, Confluence is faster by a factor of 30.
I can’t do global satellite hydrology without this system. Or, I could, but it would be extremely time consuming and expensive.
Colin Gleason
Nikki Tebaldi, a Cloud Adoption Engineer at NASA’s Jet Propulsion Laboratory (JPL) and Co-Investigator for Confluence, was the lead developer on this project. She said that while the individual components of Confluence have been around for decades, bringing them together within a single, cloud-based processing pipeline was a significant challenge.
“I’m really proud that we’ve pieced together all of these different algorithms, got them into the cloud, and we have them all executing commands and working,” said Tebaldi.
Suresh Vannan, former manager of PO.DAAC and a Co-Investigator for Confluence, said this new ability to produce timely, global estimates of river discharge and quality will have a huge impact on hydrological models assessing everything from the health of river ecosystems to snowmelt.
“There are a bunch of science applications that river discharge can be used for, because it’s pretty much taking a snapshot of what the river looks like, how it behaves. Producing that snapshot on a global scale is a game changer,” said Vannan.
While the Confluence team is still working with PO.DAAC to complete their software package, users can currently access the Confluence source code here. For tutorials, manuals, and other user guides, visit the PO.DAAC webpage here.
All of these improvements to the original Confluence algorithms developed for SWOT were made possible by NASA’s Advanced Intelligent Systems Technology (AIST) program, a part of the agency’s Earth Science Technology Office (ESTO), in collaboration with SWOT and PO.DAAC.
To learn more about opportunities to develop next-generation technologies for studying Earth from outer space, visit ESTO’s solicitation page here.
Project Lead: Colin Gleason / University of Massachusetts, Amherst
Sponsoring Organization: Advanced Intelligent Systems Technology program, within NASA’s Earth Science Technology Office
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Last Updated Feb 04, 2025 Related Terms
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By NASA
For astronauts aboard the International Space Station, staying connected to loved ones and maintaining a sense of normalcy is critical. That is where Tandra Gill Spain, a computer resources senior project manager in NASA’s Avionics and Software Office, comes in. Spain leads the integration of applications on Apple devices and the hardware integration on the Joint Station Local Area Network, which connects the systems from various space agencies on the International Space Station. She also provides technical lead support to the Systems Engineering and Space Operations Computing teams and certifies hardware for use on the orbiting laboratory.
Spain shares about her career with NASA and more. Read on to learn about her story, her favorite project, and the advice she has for the next generation of explorers.
Tandra Spain’s official NASA portrait. NASA Where are you from?
I am from Milwaukee, Wisconsin.
Tell us about your role at NASA.
I am the Apple subsystem manager where I lead the integration of applications on Apple devices as well as the hardware integration on the Joint Station Local Area Network. We use a variety of different software but I work specifically with our Apple products. I also provide technical lead support to the Systems Engineering and Space Operations Computing teams. In addition, I select and oversee the certification of hardware for use on the International Space Station, and I research commonly used technology and assess applicability to space operations.
How would you describe your job to family or friends who may not be familiar with NASA?
I normalize living and working in space by providing the comforts and conveniences of living on Earth.
Tandra spain
Computer Resources Senior Project Manager
I get the opportunity to provide the iPads and associated applications that give astronauts the resources to access the internet. Having access to the internet affords them the opportunity to stay as connected as they desire with what is going on back home on Earth (e.g., stream media content, stay in touch with family and friends, and even pay bills). I also provide hardware such as Bluetooth speakers, AirPods, video projectors, and screens.
How long have you been working for NASA?
I have been with the agency for 30 years, including 22 years as a contractor.
What advice would you give to young individuals aspiring to work in the space industry or at NASA?
I have found that there is a place for just about everyone at NASA, therefore, follow your passion. Although many of us are, you don’t have to be a scientist or engineer to work at NASA. Yearn to learn. Pause and listen to those around you. You don’t know what you don’t know, and you will be amazed what gems you’ll learn in the most unexpected situations.
Additionally, be flexible and find gratitude in every experience. Many of the roles that I’ve had over the years didn’t come from a well-crafted, laid-out plan that I executed, but came from taking advantage of the opportunities that presented themselves and doing them to the best of my ability.
Tandra Spain and her husband, Ivan, with NASA astronaut and Flight Director TJ Creamer when she was awarded the Silver Snoopy Award. What was your path to NASA?
I moved to Houston to work at NASA’s Johnson Space Center immediately upon graduating from college.
Is there someone in the space, aerospace, or science industry that has motivated or inspired you to work for the space program? Or someone you discovered while working for NASA who inspires you?
I spent over half of my career in the Astronaut Office, and I’ve been influenced in different ways by different people, so it wouldn’t be fair to pick just one!
What is your favorite NASA memory?
I’ve worked on so many meaningful projects, but there are two recent projects that stand out.
Humans were not created to be alone, and connection is extremely important. I was able to provide a telehealth platform for astronauts to autonomously video conference with friends and family whenever an internet connection is available. Prior to having this capability, crew were limited to one scheduled video conference a week. It makes me emotional to think that we have moms and dads orbiting the Earth on the space station and they can see their babies before they go to bed, when they wake up in the morning, or even in the middle of the night if needed.
In addition, since iPads are used for work as well as personal activities on station, it is important for my team to be able to efficiently keep the applications and security patches up to date. We completed the software integration and are in the process of wrapping up the certification of the Mac Mini to provide this capability. This will allow us to keep up with all software updates that Apple releases on a regular basis and minimize the amount of crew and flight controller team time associated with the task by approximately 85%.
Tandra Spain, her mother, Marva Herndon, and her daughter, Sasha, at her daughter’s high school graduation in 2024. What do you love sharing about station? What’s important to get across to general audiences to help them understand the benefits to life on Earth?
When I speak to the public about the space station, I like to compare our everyday lives on Earth to life on the station and highlight the use of technology to maintain the connection to those on Earth. For example, most people have a phone. Besides making a phone call, what do you use your phone for? It is amazing to know that the same capabilities exist on station, such as using apps, participating in parent teacher conferences, and more.
If you could have dinner with any astronaut, past or present, who would it be?
I would have dinner with NASA astronaut Ron McNair. He graduated from the same university as I did, and I’ve heard great stories about him.
Do you have a favorite space-related memory or moment that stands out to you?
As I mentioned previously, human connection is extremely important. As an engineer in the Astronaut Office, I worked on a project that provided more frequent email updates when Ku-Band communication was available. Previously, email was synced two to three times a day, and less on the weekend. When the capability went active, I sent the first email exchange.
What are some of the key projects you’ve worked on during your time at NASA? What have been your favorite?
There have been so many projects over the past 30 years that I don’t think I could select just one. There is something however, that I’ve done on many occasions that has brought me pure joy, which is attending outreach events as Johnson’s “Cosmo” mascot, especially Houston Astros games.
Tandra Spain representing NASA as “Cosmo” the astronaut mascot at a Houston Astros baseball game. What are your hobbies/things you enjoy outside of work?
I enjoy crafting, traveling, mentoring students in Pearland Independent School District, spending time with family, and my Rooted Together community.
Day launch or night launch?
Night launch!
Favorite space movie?
Star Wars (the original version)
NASA “worm” or “meatball” logo?
Meatball
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