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By NASA
Name: Dr. Inia Soto Ramos
Title and Formal Job Classification: Associate Research Scientist
Organization: Ocean Ecology Laboratory (Code 616) via Morgan State University and GESTAR II cooperative agreement
Dr. Inia Soto Ramos is an associate research scientist with NASA’s PACE — the Plankton, Aerosol, Cloud, ocean Ecosystem mission — at the agency’s Goddard Space Flight Center in Greenbelt, Md.Photo courtesy of Inia Soto Ramos What do you do and what is most interesting about your role here at Goddard?
I am currently co-leading the validation efforts for PACE, NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem mission. I am also part of NASA’s SeaBASS (SeaWiFS Bio-optical Archive and Storage System) team, which is responsible for archiving, distributing, and managing field data used for validation and development of satellite ocean color data products. It has been exciting to be a part of a satellite mission, to see it being built, tested and launched. And now, be able to validate the data and in the near future, use the data to do science.
What is your educational background?
I graduated with a bachelor’s degree in biology from The University of Puerto Rico, Mayagüez Campus, and I have a master’s and Ph.D. in Biological Oceanography from the University of South Florida.
How did you get your foot in the door at NASA?
While I was a student at the University of Puerto Rico, I saw a flyer for a program called PaSCoR (Partnership for Spatial and Computational Research). It was a partnership between universities, NASA and other institutions with the intent to train students in remote sensing and Geographical Information Systems. Although, this program was targeted mainly for engineers, I decided to apply. That took me to the first remote sensing classes I had taken. That’s how I started learning that you can study the ocean from space. I had no idea that could be done. That program planted the curiosity about satellite oceanography and gave me the tools to go into graduate school in that field.
How did you first gain exposure to oceanography and diving?
I am from Puerto Rico and grew up all the way in the mountains. There wasn’t much of a connection to the ocean for me, only a few trips to the beach. I remember my dad taking me to a small beach called La Poza del Obispo in Arecibo and he held me while I used a small snorkel underwater. That was the first connection I had with marine life. I started diving sometime when I was about 18 years old, and I remember saying, “This is the most amazing thing ever,” and that’s when I decided I needed to pursue a life in that field.
What interested you in phytoplankton as a specialty?
Initially, I was curious about harmful algal blooms in the West Florida Shelf, which I studied when I moved to Florida to do my grad studies. I learned that the blooms can produce neurotoxins, and those can affect humans in different ways. So, if you have asthma, they can make you feel worse. I remember developing asthma that night after going to the beach and having go to the ER. I didn’t see the connection at the time until I learned about these events and how toxins can get in the air. It felt like something important that I could study to help people or do something that’s meaningful. It’s amazing that we can see something so tiny from space and study them.
How does your identity, being a Latina, show up at NASA?
This is kind of a dream come true. It is so amazing to be able to fulfill that dream. I came from a small town. There appeared to me no chances to come all the way to NASA. So, having this opportunity is exciting, and bringing it back to my community and saying, “Hey, anyone can actually do it.” One of the advantages is that you speak a different language, so you can make connections with different countries.
What do you look forward to in the future? What are some of your goals?
I would love to keep growing in my field. As a mother, sometimes is hard to visualize where I want to be in the future, so I find it best to focus on the present. My priority right now is my family, however in the future I would love to engage in a job in which I can transfer my knowledge and love to the oceans to future generations; and be more involved in the community.
When you think of your village and growing up in Puerto Rico, what is a memory you have that makes you smile?
I still remember going to collect coffee with my mom and dad. My dad had a small basket for me that I would fill with only the most beautiful red grains of coffee. I was around 5 years old, and I remember the toys that my mom would take, and they’d settle me under the coffee trees. I still go to Puerto Rico, and I am fascinated when I see the coffee trees; it reminds me of my childhood.
What advice would you give to other little girls who might not think NASA is a dream they can achieve?
I was the little girl with the dream of being a scientist at NASA, and then I was a teenager, an adult, and a mother, all with the same dream! It took me several decades and many life stages to get here. Many times, along my path, I thought of giving up. Others, I thought I was completely off track and I would never fulfill my dream. I had limited resources while growing up. There were no fancy swimming or piano classes, but I had amazing teachers and mentors who guided me along the way. So, no matter how young or old you are, you can still fulfill that dream. The key to success is to know where you want to go, surround yourself with people that believe in you, and if you fall, just shake it off and try again!
By Alexa Figueroa
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Conversations With Goddard is a collection of Q&A profiles highlighting the breadth and depth of NASA’s Goddard Space Flight Center’s talented and diverse workforce. The Conversations have been published twice a month on average since May 2011. Read past editions on Goddard’s “Our People” webpage.
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Last Updated Nov 12, 2024 EditorRob GarnerContactRob Garnerrob.garner@nasa.govLocationGoddard Space Flight Center Related Terms
People of Goddard Earth Goddard Space Flight Center PACE (Plankton, Aerosol, Cloud, Ocean Ecosystem) People of NASA SeaWiFS (Sea-viewing Wide Field-of-view Sensor) View the full article
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By NASA
Earth Observer Earth Home Earth Observer Home Editor’s Corner Feature Articles Meeting Summaries News Science in the News Calendars In Memoriam More Archives 22 min read
Summary of the Second OMI–TROPOMI Science Team Meeting
Introduction
The second joint Ozone Monitoring Instrument (OMI)–TROPOspheric Monitoring Instrument (TROPOMI) Science Team (ST) meeting was held June 3–6, 2024. The meeting used a hybrid format, with the in-person meeting hosted at the National Center for Atmospheric Research (NCAR) in Boulder, CO. This was the first OMI meeting to offer virtual participation since the COVID-19 travel restrictions. Combining the onsite and virtual attendees, the meeting drew 125 participants – see Photo.
OMI flies on NASA’s Earth Observing System (EOS) Aura platform, launched July 15, 2004. TROPOMI flies on the European Space Agency’s (ESA)–Copernicus Sentinel-5 Precursor platform. OMI has collected nearly 20 years of data and TROPOMI now has amassed 5 years of data.
Meeting content was organized around the following four objectives:
discussion of the final reprocessing of OMI data (called Collection 4) and of data preservation; discussion of OMI data continuity and enhancements using TROPOMI measurements; development of unique TROPOMI products [e.g., methane (CH4)], applications (e.g., tracking emissions – and using them as indicators of socioeconomic and military activities), and new focus regions (e.g., Africa); and leverage synergies between atmospheric composition (AC) and greenhouse gas (GHG) missions, which form the international constellation of low Earth orbit (LEO) and geostationary orbit (GEO) satellites. The remainder of this article summarizes the highlights from each day of the meeting.
Photo. Group photo of the in-person participants at the OMI–TROPOMI Science Team meeting. Photo credit: Shaun Bush/NCAR’s Atmospheric Chemistry Observations & Modeling DAY ONE
The topics covered on the first day of the meeting included OMI instrument performance, calibration, final Collection 4 reprocessing, and plans for data preservation.
OMI and Data Products Update
Pieternel Levelt [Royal Netherlands Meteorological Institute (KNMI)—OMI Principal Investigator (PI) and NCAR’s Atmospheric Chemistry Observations & Modeling (ACOM) Laboratory—Director] began her presentation by dedicating the meeting to the memory of Johan de Vries, whose untimely death came as a shock to the OMI and TROPOMI teams – see In Memoriam: Johan de Vries for a celebration of his accomplishments and contributions to the OMI-TROPOMI team. She then went on to give a status update on OMI, which is one of two currently operating instruments on EOS Aura [the other being the Microwave Limb Sounder (MLS)]. OMI is the longest operating and stable ultraviolet–visible (UV-VIS) spectrometer. It continues to “age gracefully” thanks to its design, contamination control measures undertaken after the launch, and stable optical bench temperature. Lessons learned during integration of OMI on the Aura spacecraft (e.g., provide additional charged couple device shielding) and operations (i.e., monitor partial Earth-view port blockages) guided the development and operations of the follow-on TROPOMI mission.
Continued monitoring of OMI performance is crucial for extending science- and trend-quality OMI records to the end of the Aura mission (currently expected in 2026). Antje Ludewig [KNMI] described the new OMI Level-1B (L1B) processor (Collection 4), which is based on TROPOMI data flow and optimized calibrations. The processor has been transferred to the U.S. OMI ST, led by Joanna Joiner [NASA’s Goddard Space Flight Center (GSFC)]. Matthew Bandel [Science Systems and Applications, Inc. (SSAI)] described NASA’s new OMI monitoring tools.
Sergey Marchenko [SSAI] discussed OMI daily spectral solar irradiance (SSI) data, which are used for monitoring solar activity and can be compared with the dedicated Total and Spectral Solar Irradiance Sensor (TSIS-1) on the International Space Station. Continuation of OMI measurements will allow comparisons with the upcoming NASA TSIS-2 mission. Antje Inness [European Centre for Medium-range Weather Forecasts (ECMWF)] described operational assimilation of OMI and TROPOMI near-real time data into the European Copernicus Atmosphere Monitoring Service (CAMS) daily analysis/forecast and re-analysis – see Figure 1.
In Memoriam: Johan de Vries
Johan de Vries
June 10, 1956 – May 8, 2024 Johan de Vries [Airbus Netherlands—Senior Specialist Remote Sensing] passed away suddenly on May 8, 2024, after a distinguished career. As a member of the Ozone Monitoring Instrument (OMI)–TROPOspheric Monitoring Instrument (TROPOMI) program, Johan conceptualized the idea of using a two-dimensional (2D) charged couple detector (CCD) for the OMI imaging spectrometer. This “push-broom” design led to high-spatial resolution spectra combined with high-spatial resolution and daily global coverage capability. His pioneering design for OMI has now been repeated on several other U.S. and international atmospheric composition measuring instruments – in both low and geostationary orbits – that are either in orbit or planned for launch soon. This achievement ensures that Johan’s legacy will live on for many years to come as these push-broom Earth observing spectrometers result in unprecedented data for environmental research and applications. The OMI and TROPOMI teams express their deepest condolences to de Vries family and colleagues over this loss.
Figure 1. An example of TROPOMI pixel nitrogen dioxide (NO2) observations over Europe on September 8, 2018 [top] and the corresponding super observations [bottom] for a model grid of 0.5 x 0.5o. Cloudy locations are colored grey. TROPOMI super observations are tested for use in the European Centre for Medium Range Weather Forecasting (ECMWF) Copernicus Atmosphere Monitoring Service (CAMS) data assimilation framework and will also be used for combined OMI–TROPOMI gridded datasets. Figure credit: reprinted from a 2024 paper posted on EGUSphere. Updates on OMI and TROPOMI Level-2 Data Products
The U.S. and Netherlands OMI STs continue to collaborate closely on reprocessing and improving OMI and TROPOMI L2 science products. During the meeting, one or more presenters reported on each product, which are described in the paragraphs that follow.
Serena Di Pede [KNMI] discussed the latest algorithm updates to the Collection 4 OMI Total Column Ozone (O3) product, which is derived using differential absorption spectroscopy (DOAS). She compared results from the new algorithm with the previous Collection 3 and with both the TROPOMI and OMI NASA O3 total column (Collection 3) algorithms. Collection 4 improved on previous versions by reducing the retrieval fit error and the along-track stripes of the product.
Juseon “Sunny” Bak and Xiong Liu [both from Smithsonian Astrophysical Observatory (SAO)] gave updates on the status of the Collection 4 O3 profile products.
Lok Lamsal [GSFC/University of Maryland, Baltimore County (UMBC)] and Henk Eskes [KNMI] compared Collection 3 and Collection 4 of the nitrogen dioxide (NO2) products.
Zolal Ayzpour [SAO] discussed the status of the OMI Collection 4 formaldehyde (HCHO) product.
Hyeong-Ahn Kwon [SAO] presented a poster that updated the Glyoxal product.
Omar Torres [GSFC] and Changwoo Ahn [GSFC/SSAI] presented regional trend analyses using the re-processed OMI Collection 4 absorbing aerosol product – see Figure 2.
Figure 2. Reprocessed OMI records (from Collection 4) of monthly average aerosol optical depth (AOD) at 388 nm derived from the OMI aerosol algorithm (OMAERUV) over Western North America (WNA): 30°N–50°N, 110°W–128°W) [top] and over Eastern China (EC): 25°N–43°N, 112°E–124°E) [bottom]. A repeatable annual cycle over WNA occurred with autumn minimum at around 0.1 and a spring maximum in the vicinity of 0.4 during the 2005–2016 period. After 2017 much larger AOD maxima in the late summer are associated with wildfire smoke occurrence. Over EC (bottom) the 2005–2014 AOD record depicts a large spring maxima (0.7 and larger) due to long-range transport of dust and secondary pollution aerosols followed by late autumn minima (around 0.3). A significant AOD decrease is observed starting in 2015 with reduced minimum and maximum values to about 0.2 and 0.5 respectively. The drastic change in AOD load over this region is associated with pollution control measures enacted over the last decade. Figure credit: Changwoo Ahn/GSFC/SSAI and Omar Torres/GSFC Updates on EOS Synergy Products
Several presenters and posters during the meeting gave updates on EOS synergy products, where OMI data are combined with data from another instrument on one of the EOS flagships. These are described below.
Brad Fisher [SSAI] presented a poster on the Joint OMI–Moderate Resolution Imaging Spectroradiometer (MODIS) cloud products.
Wenhan Qin [GSFC/SSAI] presented a poster on the MODIS–OMI Geometry Dependent Lambertian Equivalent Surface Reflectivity (GLER) product.
Jerry Ziemke [GSFC and Morgan State University (MSU)] presented on the OMI–MLS Tropospheric Ozone product that showed post-COVID tropospheric O3 levels measured using this product, which are consistent with similar measurements obtained using other satellite O3 data – see Figure 3.
Figure 3. Anomaly maps of merged tropospheric column O3 (TCO) satellite data (Dobson Units) for spring–summer 2020–2023. In this context, an anomaly is defined as deseasonalized O3 data. The anomaly maps are derived by first calculating seasonal climatology maps for 2016–2019 (i.e., pre-COVID pandemic) and then subtracting these climatology maps from the entire data record.
Note: The sensors used in this analysis include: the Ozone Mapping and Profiler Suite (OMPS)/ Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) and Cross-track Infrared Sounder (CrIS) on the Joint Polar Satellite System (JPSS) missions, which currently include the joint NASA–NOAA Suomi National Polar-orbiting Partnership (Suomi NPP), NOAA-20, and NOAA-21; the Earth Polychromatic Imaging Camera (EPIC)/MERRA-2 on the Deep Space Climate Observatory (DSCOVR); the Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS), both on EOS Aura; the Infrared Atmospheric Sounding Interferometer (IASI)/ Fast Optimal Retrievals on Layers (FORLI), IASI/SOftware for Fast Retrievals of IASI Data (SOFRID), and IASI/Global Ozone Monitoring Experiment–2 (GOME2). IASI flies on the European MetOp-A, -B, and -C missions. The OMPS/MERRA-2 and EPIC/MERRA-2 products subtract coincident MERRA-2 stratospheric column O3 from total O3 to derive tropospheric column O3. Figure credit: Jerry Ziemke/GSFC and Morgan State University (MSU) Updates on Multisatellite Climate Data Records
The OMI ST also discussed refining and analyzing multisatellite climate data records (CDRs) that have been processed with consistent algorithms. Several presenters reported on this work, who are mentioned below.
Jenny Stavrakou [Koninklijk Belgisch Instituut voor Ruimte-Aeronomie, Royal Belgian Institute for Space Aeronomy (BIRA–IASB)], reported on work focusing on the OMI and TROPOMI HCHO CDR and Huan Yu [BIRA–IASB)] reported harmonized OMI and TROPOMI cloud height datasets based on improved O2-O2 absorption retrieval algorithm.
Lok Lamsal [GSFC/UMBC, Goddard Earth Sciences Technology and Research (GESTAR) II], Henk Eskes, and Pepijn Veefkind [KNMI] reported on the OMI and TROPOMI NO2 CDRs – see Figure 4.
Si-Wan Kim [Yonsei University, South Korea] reported on OMI and TROPOMI long-term NO2 trends.
Figure 4. OMI nitrogen dioxide (NO2) time series bridging the first GOME mission (which flew on the European Remote Sensing Satellite–2 (ERS–2) from 1995–2011 with limited coverage after 2003) and measurements from the two currently operating missions – OMI (2004–present) and TROPOMI (2017–present) – offer consistent climate data records that allow for studying long-term changes. This example shows tropospheric NO2 column time series from three instruments over Phoenix, AZ. The overlap between the OMI and TROPOMI missions allows for intercomparison between the two, which is crucial to avoid continuity-gaps in multi-instrument time series. The ERS-2 (GOME) had a morning equator crossing time (10:30 AM), while Aura (OMI) and Metop (TROPOMI) have afternoon equator crossing times of 1:45 PM and 1:30 PM respectively. Figure credit: Lok Lamsal/GSFC/University of Maryland, Baltimore County (UMBC) Update on Aura’s Drifting Orbit
Bryan Duncan [GSFC—Aura Project Scientist] closed out the first day with a presentation summarizing predictions of Aura’s drifting orbit. Overall, the impact of Aura’s drift is expected to be minor, and the OMI and MLS teams will be able to maintain science quality data for most data products. He thanked the OMI/TROPOMI ST and user community for expressing their strong support for continuing Aura observations until the end of the Aura mission in mid–2026.
DAY TWO
The second day of the meeting focused on current and upcoming LEO and GEO Atmospheric Composition (AC) missions.
TROPOMI Mission and Data Product Updates
Veefkind presented an update on the TROPOMI mission, which provides continuation and enhancements for all OMI products. Tobias Borssdorf [Stichting Ruimte Onderzoek Nederland (SRON), or Netherlands Institute for Space Research] explained how TROPOMI, with its innovative shortwave infrared (SWIR) spectrometer, measures CH4 and carbon monoxide (CO). This approach continues measurements that began by the Measurements of Pollution in the Troposphere (MOPITT) instrument on Terra.
Hiren Jethva [NASA Airborne Science Program] and Torres presented new TROPOMI near-UV aerosol products, including a new aerosol layer optical centroid height product, which takes advantage of the TROPOMI extended spectral range – see Figure 5.
Figure 5. Global gridded (0.10° x 0.10°) composite map of aerosol layer optical centroid height (AH) retrieved from TROPOMI O2-B band observations from May–September 2023. Figure credit: Hiren Jethva/NASA Airborne Science Program GEMS–TEMPO–Sentinel-4 (UVN): A Geostationary Air Quality Constellation
TROPOMI global observations serve as a de facto calibration standard used to homogenize a new constellation of three missions that will provide AC observations for most of the Northern Hemisphere from GEO. Two of the three constellation members are already in orbit. Jhoon Kim [Yonsei University—PI] discussed the Geostationary Environmental Monitoring Spectrometer (GEMS), launched on February 19, 2020 aboard the Republic of Korea’s GEO-KOMPSAT-2B satellite. It is making GEO AC measurements over Asia. The GEMS team is working on validating measurements of NO2 diurnal variations using ground-based measurements from the PANDORA Global Network over Asia and aircraft measurements from the ASIA–AQ field campaign.
Liu discussed NASA’s Tropospheric Emission Monitoring of Pollution (TEMPO) spectrometer, launched on April 7, 2023, aboard a commercial INTELSAT 40E satellite. From its GEO vantage point, TEMPO can observe the Continental U.S., Southern Canada, Mexico, and the coastal waters of the Northwestern Atlantic and Northeastern Pacific oceans.
Gonzales Abad [SAO] presented the first measurements from TEMPO. He explained that TEMPO’s design is similar to GEMS, but GEMS includes an additional visible and near infrared (VNIR) spectral channel (540–740 nm) to measure tropospheric O3, O2, and water vapor (H2Ov). TEMPO can perform optimized morning scans, twilight scans, and scans with high temporal resolution (5–10 minutes) over selected regions. Abad reported that the TEMPO team released L1B spectra and the first provisional public L2 products (Version 3), including NO2, HCHO, and total column O3. Andrew Rollins [National Oceanic and Atmospheric Administration’s (NOAA) Chemical Sciences Laboratory (CSL)] reported that the TEMPO team is working on validation of provisional data using both ground-based data from PANDORA spectrometers and data collected during several different airborne campaigns completed during the summer of 2023 and compiled on the AGES+ website.
Ben Veihelmann [ESA’s European Space Research and Technology Center—PI] explained that ESA’s Copernicus Sentinel-4 mission will be the final member of the GEO AC constellation. Veefkind summarized the Sentinel-4 mission, which is expected to launch on the Meteosat Third Generation (MTG)-Sounder 1 (MTG-S1) platform in 2025. The mission is dedicated to measuring air quality and O3 over Europe and parts of the Atlantic and North Africa. Sentinel-4 will deploy the first operational UV-Vis-NIR (UVN) imaging spectrometer on a geostationary satellite. (Airbus will build UVN, with ESA providing guidance.) Sentinel-4 includes two instruments launched in sequence on MTG-S1 and MTG-S2 platforms designed to have a combined lifetime of 15 years. The mission by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) will operate Sentinel-4, and the Deutsches Zentrum für Luft- und Raumfahrt (DLR) or German Aerospace Center will be responsible for operational L2 processing.
These three GEO AC missions, along with the upcoming ESA/EUMETSAT/Copernicus LEO (morning orbit, 9:30 a.m.) Sentinel-5 (S5) mission, will complete a LEO–GEO satellite constellation that will enable monitoring of the most industrialized and polluted regions in the Northern Hemisphere into the 2030s. Sentinel-5 will not continue the OMI–TROPOMI data record in the early afternoon; however, it will be placed in the morning orbit and follow ESA’s Global Ozone Monitoring Experiment (GOME) and EUMETSAT GOME-2 missions. By contrast, GEO AC observations over the Southern Hemisphere are currently not available. Several presenters described ongoing projects for capacity building for LEO satellite air quality data uptake and emission monitoring in Africa and advocated for the new geostationary measurements.
Synergy with Other Current or Upcoming Missions
Attendees discussed the synergy between upcoming AC, GHG, and ocean color missions. Current trends in satellite AC measurements are toward increased spatial resolution and combined observations of short-lived reactive trace gases – which are important for air quality (AQ) monitoring – and long-lived GHG – which are important for climate monitoring and carbon cycle assessments. Some trace gases (e.g., O3 and CH4) are both polluters and GHG agents. Others [e.g., NO2 and sulfur dioxide (SO2 )] are aerosol [particulate matter (PM)] and O3 precursors and are used as proxies and spatial indicators for anthropogenic CO2 and CH4 emissions.
Yasjka Meijer [ESA—Copernicus Anthropogenic Carbon Dioxide Monitoring (CO2M) Mission Scientist]) reviewed the plans for CO2M, which includes high-resolution measurements [~4 km2 (~1.5 mi2)] of CO2 , CH4 , and NO2.
Jochen Landgraf [SRON] described ESA’s new Twin Anthropogenic Greenhouse Gas Observers (TANGO) mission, which has the objective to measure CO2 , CH4 , and NO2 at even higher spatial resolution [~300 m (~984 ft)] using two small CubeSat spectrometers flying in formation.
Hiroshi Tanimoto [National Institute for Environmental Studies, Japan] described the Japan Aerospace Exploration Agency’s (JAXA) Global Observing SATellite for greenhouse gases and water cycle (GOSAT-GW) mission, which includes the Total Anthropogenic and Natural Emission mapping SpectrOmeter (TANSO-3) spectrometer to simultaneously measure CO2 , CH4, and NO2 with ~1–3 km (~0.6–1.8 mi) spatial resolution in focus mode. GOSAT-GW will also fly the Advanced Microwave Scanning Radiometer 3 (AMSR3).
Joanna Joiner [GSFC—Geostationary Extended Operations (GeoXO) Project Scientist and ACX Instrument Scientist] described the plans for the next-generation U.S. geosynchronous satellite constellation, which will consist of three satellites covering the full Earth disk: GEO-East, GEO-West, and GEO-Central. (By contrast, the current Geostationary Operational Environmental Satellite (GOES) series has two satellites: GOES–East and GOES–West.) GEO-Central will carry an advanced infrared sounder (GXS) for measuring vertical profiles of many trace gases, temperature and humidity, and a new UV-VIS spectrometer (ACX), which is a follow-on to TEMPO for AQ applications. Both GXS and ACX instruments will be built by BAE Systems, which acquired Ball Aerospace and Technology, and will also build the GeoXO ocean color spectrometer (OCX).
Andrew Sayer [UMBC] described NASA’s Plankton, Aerosols, Clouds, and ocean Ecosystem (PACE), which launched on February 8, 2024. The PACE payload includes a high-spatial resolution [~1 km (~0.6 mi) at nadir] Ocean Color Instrument (OCI), which is a UV-Vis-NIR spectrometer with discrete SWIR bands presenting additional opportunities for synergistic observations with the AC constellation. Sayer presented OCI “first light” aerosol data processed using the unified retrieval algorithm developed by Lorraine Remer [UMBC].
The second day concluded with a joint crossover session with NASA’s Health and Air Quality Applied Sciences Team (HAQAST) followed by a poster session. Several OMI–TROPOMI STM participants presented on a variety of topics that illustrate how OMI and TROPOMI data are being used to support numerous health and AQ applications. Duncan, who is also a member of HAQAST team, presented “20 years of health and air quality applications enabled by OMI data.” He highlighted OMI contributions to AQ and health applications, including NO2 trend monitoring, inferring trends of co-emitted species [e.g., CO2, CO, some Volatile Organic Compounds (VOCs)], validation of new satellite missions (e.g., TEMPO, PACE), and burden of disease studies.
DAY THREE
Discussions on the third day focused on advanced retrieval algorithms, leading to new products and new applications for OMI and TROPOMI data. Several presentations described applications of TROPOMI CH4 data and synergy with small satellites.
Advanced Retrieval Algorithms and New Data Products
Ilse Aben [SRON] described TROPOMI global detection of CH4 super-emitters using an automated system based on Machine Learning (ML) techniques – see Figure 6. Berend Schuit [SRON] provided additional detail on these methods. He introduced the TROPOMI CH4 web site to the meeting participants. He explained how TROPOMI global CH4 measurements use “tip-and-cue” dedicated satellites with much higher spatial resolution instruments [e.g., GHGSat with ~25-m (~82-ft) resolution] to scan for individual sources and estimate emission rates. Most CH4 super-emitters are related to urban areas and/or landfills, followed by plumes from gas and oil industries and coal mines.
Figure 6. Methane plume map produced by SRON shows TROPOMI large CH4 emission plumes for the week of the OMI–TROPOMI meeting (June 3–6, 2024). Figure credit: Itse Aben/Stichting Ruimte Onderzoek Nederland (SRON) Alba Lorente [Environmental Defense Fund—Methane Scientist] introduced a new MethaneSAT satellite launched in March 2024, which aims to fill the gap in understanding CH4 emissions on a regional scale [200 x 200 km2 (~77 x 77 mi2)] from at least 80% of global oil and gas production, agriculture, and urban regions. Alex Bradley [University of Colorado, Boulder] described improvements to TROPOMI CH4 retrievals that were achieved by correcting seasonal effects of changing surface albedo.
Daniel Jacob [Harvard University] presented several topics, including the highest resolution [~30 m (~98 ft)] NO2 plume retrievals from Landsat-8 – see Figure 7 – and Sentinel-2 imagers. He also discussed using a ML technique trained with TROPOMI data to improve NO2 retrievals from GEMS and modeling NO2 diurnal cycle and emission estimates. He introduced the ratio of ammonia (NH3) to NO2 (NH3/NO2) as an indicator of particulate matter with diameters less than 2.5 µm (PM2.5) nitrate sensitivity regime. Jacob emphasized the challenges related to satellite NO2 retrievals (e.g., accounting for a free-tropospheric NO2 background and aerosols).
Figure 7. Landsat Optical Land Imager (OLI) image, obtained on October 17, 2021 over Saudi Arabia, shows power plant exhaust, which contains nitrogen dioxide (NO2) drifting downwind from the sources (the two green circles are the stacks). The ultra-blue channel (430–450 nm) on OLI enables quantitative detection of NO2 in plumes from large point sources at 30-m (~98-ft) resolution. This provides a unique ability for monitoring point-source emissions of oxides of nitrogen (NOx). The two stacks in the image are separated by 2 km (~1.2 mi). Figure credit: Daniel Jacob – repurposed from a 2024 publication in Proceedings of the National Academies of Sciences (PNAS) Steffen Beirle [Max Planck Institute for Chemistry, Germany] explained his work to fit TROPOMI NO2 column measurements to investigate nitric oxide (NO) to NO2 processing in power plant plumes. Debra Griffin [Environment and Climate Change Canada (ECCC)] used TROPOMI NO2 observations and ML random forest technique to estimate NO2 surface concentrations. Sara Martinez-Alonso [NCAR] investigated geographical and seasonal variations in NO2 diurnal cycle using GEMS and TEMPO data. Ziemkecombined satellite O3 data to confirm a persistent low anomaly (~5–15%) in tropospheric O3 after 2020. Jethva presented advanced OMI and TROPOMI absorbing aerosol products. Yu described improved OMI and TROPOMI cloud datasets using the O2-O2 absorption band at 477 nm. Nicholas Parazoo [Jet Propulsion Laboratory (JPL)] described TROPOMI Fraunhofer line retrievals of red solar-induced chlorophyll fluorescence (SIF) near O2-B band (663–685 nm) to improve mapping of ocean primary productivity. Liyin He [Duke University] described using satellite terrestrial SIF data to study the effect of particulate pollution on ecosystem productivity.
New Applications
Zachary Fasnacht [SSAI] used OMI and TROPOMI spectra to train a neural network to gap-fill MODIS and Visible Infrared Imaging Radiometer Suite (VIIRS) ocean color data under aerosol, sun glint, and partly cloudy conditions. This ML method can also be applied to PACE OCI spectra. Anu-Maija Sundström [Finnish Meteorological Institute (FMI)] used OMI and TROPOMI SO2 and O3 data as proxies to study new particle formation events. Lindsey Anderson [University of Colorado, Boulder] described how she used TROPOMI NO2 and CO measurements to estimate the composition of wildfire emissions and their effect on forecasted air quality. Heesung Chong [SAO] applied OMI bromine oxide (BrO) retrievals to the NOAA operational Ozone Mapping and Profiling Suite Nadir Mapper (OMPS-NM) on joint NOAA–NASA Suomi-National Polar-orbiting Partnership (Suomi NPP) satellite with the possibility to continue afternoon measurements using similar OMPS-NM instruments on the four Joint Polar Satellite System missions (JPSS-1,-2,-3,-4) into the 2030s. (JPSS-1 and -2 are now in orbit and known as NOAA-20 and -21 respectively; JPSS-4 is planned for launch in 2027, with JPSS-3 currently targeted for 2032.)
Kim demonstrated the potential for using satellite NO2 and SO2 emissions as a window into socioeconomic issues that are not apparent by other methods. For example, she showed how OMI and TROPOMI data were widely used to monitor air quality improvements in the aftermath of COVID-19 lockdowns. (Brad Fisher [SSAI] presented a poster on a similar topic.)
Cathy Clerbaux [Center National d’Études Spatiale (CNES), or French Space Agency] showed how her team used TROPOMI NO2 data to trace the signal emitted by ships and used this information to determine how the shipping lanes through the Suez Canal changed in response to unrest in the Middle East. Iolanda Ialongo [FMI] showed a similar drop of NO2 emissions over Donetsk region due to the war in Ukraine. Levelt showed how OMI and TROPOMI NO2 data are used for capacity-building projects and for air quality reporting in Africa. She also advocated for additional geostationary AQ measurements over Africa.
DAY FOUR
Discussions on the final day focused on various methods of assimilating satellite data into air quality models for emission inversions and aircraft TEMPO validation campaigns. The meeting ended with Levelt giving her unique perspective on the OMI mission, as she reflected on more than two decades being involved with the development, launch, operation, and maintenance of OMI.
Assimilating Satellite Data into Models for Emissions
Brian McDonald [CSL] described advance chemical data assimilation of satellite data for emission inversions and the GReenhouse gas And Air Pollutants Emissions System (GRA2PES). He showed examples of assimilations using TROPOMI and TEMPO NO2 observations to adjust a priori emissions. He also showed that when TEMPO data are assimilated, NOx emissions adjust faster and tend to perform better at the urban scale. Adrian Jost [Max Planck Institute for Chemistry] described the ESA-funded World Emission project to improve pollutant and GHG emission inventories using satellite data. He showed examples of TROPOMI SO2 emissions from large-point sources and compared the data with bottom-up and NASA SO2 emissions catalogue.
Ivar van der Velde [SRON] presented a method to evaluate fire emissions using new satellite imagery of burned area and TROPOMI CO. Helene Peiro [SRON] described her work to combine TROPOMI CO and burned area information to compare the impact of prescribed fires versus wildfires on air quality in the U.S. She concluded that prescribed burning reduces CO pollution. Barbara Dix [University of Colorado, Boulder, Cooperative Institute for Research in Environmental Sciences] derived NOx emissions from U.S. oil and natural gas production using TROPOMI NO2 data and flux divergence method. She estimated TROPOMI CH4 emissions from Denver–Julesburg oil and natural gas production. Dix explained that the remaining challenge is to separate oil and gas emissions from other co-located CH4 sources. Ben Gaubert [NCAR, Atmospheric Chemistry Observations and Modeling] described nonlinear and non-Gaussian ensemble assimilation of MOPITT CO using the data assimilation research testbed (DART).
Andrew (Drew) Rollings [CSL] presented first TEMPO validation results from airborne field campaigns in 2023 (AGES+ ), including NOAA CSL Atmospheric Emissions and Reactions observed from Megacities to Marine Aeras (AEROMMA) and NASA’s Synergistic TEMPO Air Quality Science (STAQS) campaigns.
A Reflection on Twenty Years of OMI Observations
Levelt gave a closing presentation in which she reflected on her first involvement with the OMI mission as a young scientist back in 1998. This led to a collaboration with the international ST to develop the instrument, which was included as part of Aura’s payload when it launched in July 2004. She reminisced about important highlights from 2 decades of OMI, e.g., the 10-year anniversary STM at KNMI in 2014 (see “Celebrating Ten Years of OMI Observations,” The Earth Observer, May–Jun 2014, 26:3, 23–30), and the OMI ST receiving the NASA/U.S. Geological Survey Pecora award in 2018 and the American Meteorological Society’s Special award in 2021.
Levelt pointed out that in this combined OMI–TROPOMI meeting the movement towards using air pollution and GHG data together became apparent. She ended by saying that the OMI instrument continues to “age gracefully” and its legacy continues with the TROPOMI and LEO–GEO atmospheric composition constellation of satellites that were discussed during the meeting.
Conclusion
Overall, the second OMI–TROPOMI STM acknowledged OMI’s pioneering role and TROPOMI’s unique enhancements in measurements of atmospheric composition:
Ozone Layer Monitoring: Over the past two decades, OMI has provided invaluable data on the concentration and distribution of O3 in the Earth’s stratosphere. This data has been crucial for understanding and monitoring the recovery of the O3 layer following international agreements, such as the Montreal Protocol. Air Quality Assessment: OMI’s high-resolution measurements of air pollutants, such as NO2, SO2, and HCHO, have significantly advanced our understanding of air quality. This information has been vital for tracking pollution sources, studying their transport and transformation, and assessing their impact on human health and the environment. Climate Research: The data collected by OMI has enhanced our knowledge of the interactions between atmospheric chemistry and climate change. These insights have been instrumental in refining climate models and improving our predictions of future climate scenarios. Global Impact: The OMI instrument has provided near-daily global coverage of atmospheric data, which has been essential for scientists and policymakers worldwide. The comprehensive and reliable data from OMI has supported countless research projects and informed decisions aimed at protecting and improving our environment. OMI remains one of the most stable UV/Vis instruments over its two decades of science and trend quality data collection. The success of the OMI and TROPOMI instruments is a testament to the collaboration, expertise, and dedication of both teams.
Nickolay Krotkov
NASA’s Goddard Space Flight Center
Nickolay.a.krotkov@nasa.gov
Pieternel Levelt
National Center for Atmospheric Research, Atmospheric Chemistry Observations & Modeling
levelt@ucar.edu
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Last Updated Nov 12, 2024 Related Terms
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By NASA
Researchers demonstrated the feasibility of 3D bioprinting a meniscus or knee cartilage tissue in microgravity. This successful result advances technology for bioprinting tissue to treat musculoskeletal injuries on long-term spaceflight or in extraterrestrial settings where resources and supply capacities are limited.
BFF Meniscus-2 evaluated using the BioFabrication Facility to 3D print knee cartilage tissue using bioinks and cells. The meniscus is the first engineered tissue of an anatomically relevant shape printed on the station. Manufactured human tissues have potential as alternatives to donor organs, which are in short supply. Bioprinting in microgravity overcomes some of the challenges present in Earth’s gravity, such as deformation or collapse of tissue structures.
A human knee meniscus 3D bioprinted in space using the International Space Station’s BioFabrication Facility.Redwire Complex cultures of central nervous system cells known as brain organoids can be maintained in microgravity for long periods of time and show faster development of neurons than cultures on Earth. These findings could help researchers develop treatments for neurodegenerative diseases on Earth and address potential adverse neurological effects of spaceflight.
Cosmic Brain Organoids examined growth and gene expression in 3D organoids created with neural stem cells from individuals with primary progressive multiple sclerosis and Parkinson’s disease. Results could improve understanding of these neurological diseases and support development of new treatments. Researchers plan additional studies on the underlying causes of the accelerated neuron maturation.
Neural growth in brain organoids that spent more than a month in space. Jeanne Frances Loring, National Stem Cell Foundation Researchers demonstrated that induced pluripotent stem cells (iPSCs) can be processed in microgravity using off the-shelf cell culture materials. Using standard laboratory equipment and protocols could reduce costs and make space-based biomedical research accessible to a broader range of scientists and institutions.
Stellar Stem Cells Ax-2 evaluated how microgravity affects methods used to generate and grow stem cells into a variety of tissue types on the ground. iPSCs can give rise to any type of cell or tissue in the human body, and insight into processing in space could support their use in regenerative medicine and future large-scale biomanufacturing of cellular therapeutics in space.
NASA astronaut Peggy Whitson, an Axiom Mission 2 crew member, works on stem cell research on a previous mission. NASA/Shane KimbroughView the full article
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By NASA
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
The NISAR mission will help researchers get a better understanding of how Earth’s surface changes over time, including in the lead-up to volcanic eruptions like the one pictured, at Mount Redoubt in southern Alaska in April 2009.R.G. McGimsey/AVO/USGS Data from NISAR will improve our understanding of such phenomena as earthquakes, volcanoes, and landslides, as well as damage to infrastructure.
We don’t always notice it, but much of Earth’s surface is in constant motion. Scientists have used satellites and ground-based instruments to track land movement associated with volcanoes, earthquakes, landslides, and other phenomena. But a new satellite from NASA and the Indian Space Research Organisation (ISRO) aims to improve what we know and, potentially, help us prepare for and recover from natural and human-caused disasters.
The NISAR (NASA-ISRO Synthetic Aperture Radar) mission will measure the motion of nearly all of the planet’s land and ice-covered surfaces twice every 12 days. The pace of NISAR’s data collection will give researchers a fuller picture of how Earth’s surface changes over time. “This kind of regular observation allows us to look at how Earth’s surface moves across nearly the entire planet,” said Cathleen Jones, NISAR applications lead at NASA’s Jet Propulsion Laboratory in Southern California.
Together with complementary measurements from other satellites and instruments, NISAR’s data will provide a more complete picture of how Earth’s surface moves horizontally and vertically. The information will be crucial to better understanding everything from the mechanics of Earth’s crust to which parts of the world are prone to earthquakes and volcanic eruptions. It could even help resolve whether sections of a levee are damaged or if a hillside is starting to move in a landslide.
The NISAR mission will measure the motion of Earth’s surface — data that can be used to monitor critical infrastructure such as airport runways, dams, and levees. NASA/JPL-Caltech What Lies Beneath
Targeting an early 2025 launch from India, the mission will be able to detect surface motions down to fractions of an inch. In addition to monitoring changes to Earth’s surface, the satellite will be able to track the motion of ice sheets, glaciers, and sea ice, and map changes to vegetation.
The source of that remarkable detail is a pair of radar instruments that operate at long wavelengths: an L-band system built by JPL and an S-band system built by ISRO. The NISAR satellite is the first to carry both. Each instrument can collect measurements day and night and see through clouds that can obstruct the view of optical instruments. The L-band instrument will also be able to penetrate dense vegetation to measure ground motion. This capability will be especially useful in areas surrounding volcanoes or faults that are obscured by vegetation.
“The NISAR satellite won’t tell us when earthquakes will happen. Instead, it will help us better understand which areas of the world are most susceptible to significant earthquakes,” said Mark Simons, the U.S. solid Earth science lead for the mission at Caltech in Pasadena, California.
Data from the satellite will give researchers insight into which parts of a fault slowly move without producing earthquakes and which sections are locked together and might suddenly slip. In relatively well-monitored areas like California, researchers can use NISAR to focus on specific regions that could produce an earthquake. But in parts of the world that aren’t as well monitored, NISAR measurements could reveal new earthquake-prone areas. And when earthquakes do occur, data from the satellite will help researchers understand what happened on the faults that ruptured.
“From the ISRO perspective, we are particularly interested in the Himalayan plate boundary,” said Sreejith K M, the ISRO solid Earth science lead for NISAR at the Space Applications Center in Ahmedabad, India. “The area has produced great magnitude earthquakes in the past, and NISAR will give us unprecedented information on the seismic hazards of the Himalaya.”
Surface motion is also important for volcano researchers, who need data collected regularly over time to detect land movements that may be precursors to an eruption. As magma shifts below Earth’s surface, the land can bulge or sink. The NISAR satellite will help provide a fuller picture for why a volcano deforms and whether that movement signals an eruption.
Finding Normal
When it comes to infrastructure such as levees, aqueducts, and dams, NISAR’s ability to provide continuous measurements over years will help to establish the usual state of the structures and surrounding land. Then, if something changes, resource managers may be able to pinpoint specific areas to examine. “Instead of going out and surveying an entire aqueduct every five years, you can target your surveys to problem areas,” said Jones.
The data could be equally valuable for showing that a dam hasn’t changed after a disaster like an earthquake. For instance, if a large earthquake struck San Francisco, liquefaction — where loosely packed or waterlogged sediment loses its stability after severe ground shaking — could pose a problem for dams and levees along the Sacramento-San Joaquin River Delta.
“There’s over a thousand miles of levees,” said Jones. “You’d need an army to go out and look at them all.” The NISAR mission would help authorities survey them from space and identify damaged areas. “Then you can save your time and only go out to inspect areas that have changed. That could save a lot of money on repairs after a disaster.”
More About NISAR
The NISAR mission is an equal collaboration between NASA and ISRO and marks the first time the two agencies have cooperated on hardware development for an Earth-observing mission. Managed for the agency by Caltech, JPL leads the U.S. component of the project and is providing the mission’s L-band SAR. NASA is also providing the radar reflector antenna, the deployable boom, a high-rate communication subsystem for science data, GPS receivers, a solid-state recorder, and payload data subsystem. The U R Rao Satellite Centre in Bengaluru, India, which leads the ISRO component of the mission, is providing the spacecraft bus, the launch vehicle, and associated launch services and satellite mission operations. The ISRO Space Applications Centre in Ahmedabad is providing the S-band SAR electronics.
To learn more about NISAR, visit:
https://nisar.jpl.nasa.gov
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Jet Propulsion Laboratory, Pasadena, Calif.
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Last Updated Nov 08, 2024 Related Terms
NISAR (NASA-ISRO Synthetic Aperture Radar) Earth Science Earthquakes Jet Propulsion Laboratory Natural Disasters Volcanoes Explore More
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By NASA
Successfully deployed from the space shuttle Challenger during the February 1984 STS-41B mission, the Westar 6 and Palapa B2 communications satellites ended up in incorrect orbits due to failures of their upper stage rockets. During STS-51A in November 1984, Discovery’s second trip into space, the crew of Commander Frederick H. “Rick” Hauck, Pilot David M. Walker, and Mission Specialists Joseph P. Allen, Anna L. Fisher, and Dale A. Gardner worked as a team to not only deploy two new satellites but also to retrieve the two wayward but otherwise healthy satellites for return to Earth. Hauck and Walker piloted Discovery to rendezvous with each satellite in turn, Allen and Gardner retrieved them during two spacewalks, and Fisher grappled and placed them in the payload bay for return to Earth. After refurbishment, both satellites returned to space.
Left: The STS-51A crew of Dale A. Gardner, left, David M. Walker, Anna L. Fisher, Frederick “Rick” H. Hauck, and Joseph P. Allen. Right: The STS-51A crew patch.
NASA originally designated Hauck, Walker, Allen, Fisher, and Gardner as a crew in November 1983 and assigned them to STS-41H, a mission aboard Challenger planned for late September 1984 to either deploy the second Tracking and Data Relay Satellite (TDRS) or fly a classified payload for the Department of Defense. Due to ongoing problems with the Inertial Upper Stage that failed to put the first TDRS satellite in its correct orbit during STS-6, NASA canceled STS-41H and shifted Hauck’s crew to STS-51A. In February 1984, an agreement between NASA and the Canadian government added an as-yet unnamed Canadian payload specialist to the STS-51A crew. Managers later named the Canadian as Marc Garneau and reassigned him to STS-41G.
A shuffling of payloads following the STS-41D launch abort resulted in STS-51A now deploying the Anik D2 satellite for Canada and Leasat 1 (also known as Syncom IV-1) for the U.S. Navy. By early August, the launch date had slipped to Nov. 2, with NASA considering the possibility of retrieving the two wayward satellites from STS-41B, officially adding that task on Aug. 13. NASA selected Allen in 1967 as one of 11 scientist-astronauts, while the rest of the crew hail from the Class of 1978. Hauck, on his second mission after serving as pilot on STS-7, has the distinction as the first from his class to command a shuttle mission. Allen and Gardner had each flown one previous mission, STS-5 and STS-8, respectively, while for Walker and Fisher STS-51A represented their first flight. Fisher has the distinction as the first mother in space.
Left: After its arrival from the Orbiter Processing Facility, workers in the Vehicle Assembly Building (VAB) prepare to lift Discovery for mating with an External Tank (ET) and Solid Rocket Boosters (SRBs). Middle: Workers lift Discovery to stack it with the ET and SRBs. Right: The completed stack prepares to leave the VAB for the rollout to Launch Pad 39A.
Discovery arrived back at NASA’s Kennedy Space Center (KSC) in Florida on Sept. 10, returning from Edwards Air Force Base in California following the STS-41D mission. Workers towed it to the Orbiter Processing Facility (OPF) the next day to begin the process of refurbishing it for STS-51A. On Oct. 18, they rolled it over to the Vehicle Assembly Building (VAB), for stacking with an External Tank and twin Solid Rocket Boosters.
At NASA’s Kennedy Space Center in Florida, space shuttle Discovery rolls out to Launch Pad 39A, with the Saturn V rocket on display in the foreground.
The completed stack rolled out to Launch Pad 39A on Oct. 23. Two days later, the five-member STS-51A crew participated in the Terminal Countdown Demonstration Test, essentially a dress rehearsal for the actual countdown to launch. The crew returned to KSC on Nov. 5, the day the countdown began for a planned Nov. 7 launch. High upper-level winds that day forced a one-day delay.
Left: STS-51A astronaut Dale A. Gardner trains for the capture of a satellite using the Apogee Kick Motor Capture Device. Middle: Astronaut Anna L. Fisher trains to use the Canadian-built Remote Manipulator System, or robotic arm. Right: As part of the Terminal Countdown Demonstration Test, the STS-51A astronauts practice rapid evacuation from the launch pad.
Following deployment from Challenger during STS-41B, the upper stages of both the Westar 6 and Palapa B2 satellites malfunctioned, leaving them in non-useable 160-by-600-mile-high orbits instead of the intended 22,300-mile-high geostationary orbits required for their normal operations. While both satellites remained healthy, their own thrusters could not boost them to the proper orbits. NASA devised a plan to have astronauts retrieve the satellites during spacewalks using the jetpack known as the Manned Maneuvering Unit (MMU), after which the shuttle’s Canadian-built Remote Manipulator System (RMS) or robot arm would grapple them and place them into the cargo bay for return to Earth. Astronauts had demonstrated the capability of the MMU during the STS-41C Solar Max satellite repair mission in April 1984 and NASA felt confident of its ability to capture and return Westar and Palapa.
In the weeks prior to STS-51A, ground controllers lowered the orbits of both satellites and reduced their spin rates from 50 to 1 rpm to enable capture by the shuttle astronauts. Engineers at NASA’s Johnson Space Center in Houston developed the Apogee Kick Motor Capture Device (ACD), otherwise known as the stinger due to its appearance, to allow an astronaut to capture the satellites while flying the MMU. Once relocated over the payload bay, a second astronaut would remove the satellite’s omnidirectional antenna with pruning shears and install an Antenna Bridge Structure (ABS) with a grapple fixture over the satellite’s main antenna dish. Allen would fly the MMU to capture Palapa, then he would switch roles with Gardner who would capture Westar. Fisher would use the RMS to grapple the satellites by this second fixture and lower them into specially built cradles to secure them into the payload bay.
Left: The STS-51A crew leaves crew quarters on their way to Launch Pad 39A. Middle: Liftoff of Discovery on the STS-51A mission. Right: View inside Discovery’s payload bay shortly after orbital insertion – the top of Anik D2 is visible, with Leasat 1 hidden behind it.
Space shuttle Discovery roared off KSC’s Launch Pad 39A on Nov. 8, 1984, to begin the STS-51A mission and mark the orbiter’s first return to space. For Gardner, launch day coincided with his 36th birthday. The launch took place just 26 days after the landing of the previous mission, STS-41G, a then record-breaking turnaround time between shuttle flights. Eight and a half minutes after liftoff, Discovery and its five-member crew reached space and shortly thereafter settled into a 182-by-172-mile-high initial orbit. As their first order of business, the crew checked out the RMS to ensure its functionality for the satellite captures later in the mission. They also performed the first rendezvous burn to begin the approach to the Palapa satellite. The crew then settled down for its first night’s sleep in orbit.
Left: Nighttime deploy of the Anik D2 satellite. Middle: Deploy of the Leasat 1 satellite. Right: Leasat 1 as it departs from Discovery.
The primary activity of the second flight day involved Allen deploying the 2,727-pound Anik D2 satellite via a spring ejection mechanism, occurring on time and with no issues. The crew also circularized the shuttle’s orbit at 186 miles. The next day, Gardner deployed the 17,000-pound Leasat 1 using the Frisbee style mechanism used to deploy the first Leasat during STS-41D two months earlier. With the satellite deployments complete, the crew began to focus on the rendezvous maneuvers to bring them close to the Palapa B2 satellite while Allen and Gardner verified the functionality of their spacesuits. On flight day 4, the astronauts reduced the pressure inside the shuttle from 14.7 pounds per square inch (psi) to 10.2 psi in order to prevent the spacewalking astronauts from developing the bends inside the spacesuits that operated at 4.3 psi.
Left: During the first spacewalk, Jospeh P. Allen captures the Palapa B2 satellite. Middle: Anna L. Fisher grasps Allen and Palapa with the Remote Manipulator System, or robotic arm. Right: Allen, left, and Dale A. Gardner prepare to place Palapa in its cradle in the payload bay.
On the fifth mission day, after Hauck and Walker piloted Discovery to within 35 feet of Palapa, Allen and Gardner exited the airlock to begin the spacewalk portion of the satellite capture. Allen donned the MMU mounted on the side wall of the cargo bay, attached the stinger to its arms, and flew out to Palapa. Once there, he inserted the stinger into the satellite’s Apogee Kick Motor bell and using the MMU’s attitude control system stopped Palapa’s spin.
Fisher then steered the RMS to capture a grapple fixture mounted on the stinger between Allen and the satellite. She then maneuvered them over the payload bay where Gardner waited to remove its omnidirectional antenna and install the bridge structure. However, Gardner could not attach the ABS to the satellite due to an unexpected clearance issue on the satellite. Using a backup plan, Allen undocked from the stinger, leaving it attached to the satellite as well as the RMS, and stowed the MMU in the payload bay. With Allen now holding the satellite by its antenna, Gardner attached an adaptor to the bottom end of the satellite to secure it in its cradle in the payload bay. This plan worked and Allen and Gardner completed the spacewalk in exactly six hours.
Left: Dale A. Gardner flies the Manned Maneuvering Unit to capture Westar 6 during the second spacewalk. Middle: Anna L. Fisher operates the Remote Manipulator System from Discovery’s aft flight deck. Right: Gardner, left, and Joseph P. Allen maneuver Westar prior to placing it in its cradle in the payload bay.
Between the two spacewalk days, the crew serviced the spacesuits, conducted routine maintenance on the shuttle, and prepared for the second rendezvous, this time to retrieve Westar. Allen and Gardner switched roles for the second spacewalk on flight day seven, with Gardner flying the MMU to capture Westar. The astronauts repeated the procedure from the first spacewalk, except for not removing the omni antenna so they could use it as a handhold. With Westar secured in the payload bay, Gardner and Allen completed the second spacewalk in 5 hours and 42 minutes.
Left: Dale A. Gardner, left, and Joseph P. Allen pose at the end of the Remote Manipulator System controlled by Anna L. Fisher, holding a For Sale sign above the two retrieved satellites secured in Discovery’s payload bay. Middle: Inflight photo of the STS-51A crew after the successful satellite retrievals. Right: View inside Discovery’s payload bay shortly before the deorbit burn, with Westar 6 in the foreground and Palapa B2 behind it.
During their final full day in space, Discovery’s crew repressurized the shuttle’s cabin to 14.7 psi and tidied the cabin in preparation for reentry. On Nov. 16, the astronauts closed the payload bay doors and fired the Orbital Maneuvering System engines to begin the descent back to Earth. Hauck guided Discovery to a smooth landing at KSC, completing a flight of 7 days, 23 hours, and 45 minutes. The crew had traveled nearly 3.3 million miles and completed 127 orbits around the Earth. The next day, workers towed Discovery to the OPF to begin preparing it for its next flight, STS-51C in January 1985.
Left: Discovery streaks over Houston on its way to land at NASA’s Kennedy Space Center (KSC) in Florida. Middle: Discovery moments before touchdown at KSC. Right: NASA officials greet the STS-51A astronauts as they exit Discovery.
As a postscript, STS-51A marked the last flight to use the MMUs, and the last untethered spacewalks until 1994 when STS-64 astronauts tested the Simplified Aid for EVA Rescue (SAFER). All subsequent spacewalks on the space shuttle and the International Space Station used safety tethers, with the SAFER as a backup in case a crew member disconnects from the vehicle.
Left: In the Orbiter Processing Facility at NASA’s Kennedy Space Center in Florida, workers inspect the Westar 6, left, and Palapa B2 satellites in Discovery’s payload bay. Right: The STS-51A crew, with Lloyd’s of London representative Stephen Merritt, sitting at right, during their visit to London.
On Dec. 7, 1984, in a ceremony at the White House, President Ronald W. Reagan presented the STS-51A crew with the Lloyd’s of London – the company had insured the two satellites they returned to Earth – Silver Medal for Meritorious Salvage Operations. Fisher has the distinction as only the second woman to receive that award. In February 1985, Lloyd’s flew the crew to London on the Concorde for a week of activities, including addressing the Lloyd’s underwriters and tea with Prince Charles at Kensington Palace.
Hong Kong-based AsiaSat purchased the Westar 6 satellite, refurbished it, and relaunched it as AsiaSat 1 on April 7, 1990, on a Chinese CZ-3 rocket. Title to the Palapa B2 satellite returned to Indonesia after its relaunch as Palapa B2R on April 13, 1990, aboard a Delta rocket.
Read recollections of the STS-51A mission by Hauck, Allen, and Fisher in their oral histories with the JSC History Office. Enjoy the crew’s narration of a video about the STS-51A mission.
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