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NASA's Earth Observing fleet continues to age gracefully. While several new missions have joined the fleet in the past year, scientists and engineers work to extend the life of existing missions and maximize their science along the way. The crowning example is the first Earth Observing System (EOS) Flagship mission, Terra, which celebrated a quarter-century in orbit on December 18, 2024.
Terra, continues to collect daily morning Earth observations using five different instruments: Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Clouds and the Earth's Radiant Energy System (CERES), Multi-angle Imaging SpectroRadiometer (MISR), Moderate Resolution Imaging Spectroradiometer (MODIS), and Measurement of Pollution in the Troposphere (MOPITT). Collectively, these observations have established a robust satellite record of global scientific processes to track changes in temperature, glaciers, clouds, vegetation, land-use, air quality, and natural hazards such as hurricanes, wildfires, and volcanic eruptions.
Originally designed for a six-year prime mission, Terra continues to deliver data used by emergency managers, researchers, and modelers over a quarter-of-a-century later. On December 18th, 2024, NASA celebrated the 25th anniversary of Terra's launch with a celebration at the Goddard Space Flight Center (GSFC) Visitor's Center. NASA Senior management [from NASA Headquarters and GSFC] as well as other key figures from Terra's long history gave brief remarks and perspectives on Terra's development and achievements. To read a review of the celebration, see "Celebrating 25 Years of Terra."
Terra-related sessions (poster and oral) during the Fall American Geophysical Union (AGU) meeting were well-attended. The Terra team took advantage of the meeting to have a celebratory anniversary dinner that included attendees representing each of the five instruments.
Another mission to recently reach a longevity milestone is NASA's Orbiting Carbon Observatory-2 (OCO-2), which celebrated 10 years in space last summer. OCO-2, which launched on July 2, 2014, from the Vandenburg Air Force (now Space Force) Base in California, was originally designed as a pathfinder mission to measure carbon dioxide (CO2) with the precision and accuracy needed to quantify where, when, and how the Earth inhales and exhales this important greenhouse gas seasonally. OCO-2 was part of the international Afternoon Constellation, or "A-Train," which also included Aqua, Aura, CloudSat, and CALIPSO, as well as international partner missions.
Since its launch, OCO-2 data have revealed unprecedented insights into how the carbon cycle operates - from observing the impact and recovery of tropical land and ocean ecosystems during El Niño events to revealing the outsized impacts of extreme events, such as floods, droughts, and fires on ecosystem health and functioning. Researchers from around the world use OCO-2 data, opening new opportunities for understanding the response of the carbon cycle to human-driven perturbations, such as the impact of COVID lockdowns on atmospheric CO2 and improved quantification of emissions from large power plants and cities.
OCO-2 also maps vegetation fluorescence, which shows promise as a reliable early warning indicator of flash drought. During photosynthesis, plants "leak" unused photons, producing a faint glow known as solar-induced fluorescence (SIF). The stronger the fluorescence, the more CO2 a plant is taking from the atmosphere to power its growth. Ancillary SIF measurements from OCO-2 will help scientists better predict flash droughts, and understand how these impact carbon emissions.
Ten years into the mission, OCO-2 has become the gold standard for CO2 measurements from space. The spacecraft and instrument continue to perform nominally, producing data leading to new scientific discoveries.
OCO-3, built from spare parts during the build of OCO-2 and launched to the International Space Station (ISS) in 2019, also celebrated a milestone, marking five years in orbit on May 4, 2024. While the follow-on has the same instrument sensitivity and makes essentially the same measurements as OCO-2, the vantage point on the ISS as opposed to OCO-2's polar orbit and the use of a new pointing mirror assembly (PMA) results in significant day-to-day spatial and temporal sampling differences that allows CO2 tracking for diurnal variability. In addition, the flexible PMA system allows for a much more dynamic observation-mode schedule.
Further out in space, about 1 million mi (~1.1 million km) from Earth, orbiting the "L1" Lagrange point between Earth and Sun, the Deep Space Climate Observatory (DSCOVR) celebrated the 10th anniversary of its launch on February 11, 2025. The two NASA Earth observing instruments on DSCOVR are the Earth Polychromatic Camera (EPIC) and National Institute of Standards and Technology (NIST) Advanced Radiometer [NISTAR].
The 10th DSCOVR EPIC NISTAR Science Team Meeting was held October 16-18, 2024 at Goddard Space Flight Center. Former U.S. Vice President Al Gore opened the meeting with remarks that focused on remote sensing and the future of Earth observations. Following Gore's remarks, DSCOVR mission leadership and representatives from GSFC and the National Oceanic and Atmospheric Administration (NOAA) gave presentations on DSCOVR operations, EPIC calibration, and NISTAR Status and Science.
The meeting provided an opportunity for participants to learn the status of DSCOVR's Earth-observing instruments, the status of recently released Level-2 (geophysical) data products, and the resulting science. As more people use DSCOVR data worldwide, the science team 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. For more details, see the Summary of the 10th DSCOVR EPIC and NISTAR Science Team Meeting.
Flying in the space between satellites and ground-based observations, NASA's Airborne Science Program operates a fleet of aircraft, unpiloted aerial vehicles, and even kites to study Earth and space science. Since 1987, a highly modified McDonnell Douglas DC-8 aircraft has been a mainstay of ASP's fleet - see Photo 1. The aircraft, located at NASA's Armstrong Flight Research Center (AFRC) in California, flew countless missions as a science laboratory, producing science data for the national and global scientific communities. NASA decided to retire the venerable DC-8 aircraft, which made its last science flight in April 2024. The DC-8 is being replaced with a similarly refurbished Boeing 777 aircraft, which will be even more capable than the DC-8 and is located at the NASA Langley Research Center (LaRC).
The NASA History Office and NASA Earth Science Division cohosted a workshop, titled "Contributions of the DC-8 to Earth System Science at NASA," on October 24-25, 2024 at the Mary W. Jackson NASA Headquarters (HQ) Building in Washington, DC - for more details on the DC-8 event, see the article The NASA DC-8 Retires: Reflections on its Contributions to Earth System Science.
There are also updates from three recent NASA field campaigns - where ground observations are timed and coordinated with aircraft flights (often at more than one altitude) and with satellite overpasses to gain a comprehensive (i.e., multilayered, multiscale) picture of the atmosphere over a certain area.
The Westcoast & Heartland Hyperspectral Microwave Sensor Intensive Experiment (WHyMSIE) campaign was held from October 17- November 18, 2024. Serving as a future NASA planetary boundary-layer (PBL) mission prototype, WHyMSIE aimed to capture a wide variety of thermodynamic, moisture, and PBL regimes across a variety of surface types. WHyMSIE was an initial step towards an integrated and affordable PBL observing system of systems, with multiple observing nodes - i.e., space, suborbital, and ground - from passive and active sensors to enable a comprehensive and coherent picture of essential PBL variables and hydrometeors that is not possible with any single sensor, observational approach, or scale. As a partnership between NASA and NOAA, this field campaign flew a first-of-its-kind hyperspectral microwave airborne measurements (CoSMIR-H) that was complemented by other passive (thermal emission, solar reflectance) and active (lidar, radar) sensors flying onboard the NASA ER-2 (AFRC) and G-III (LaRC), with coordination over a variety of ground-based sensor facilities.
The GSFC Lidar Observation and Validation Experiment (GLOVE) was conducted in February 2025 at Edwards Air Force Base, California - see photo 2. GLOVE flew the Cloud Physics Lidar (CPL), Roscoe lidar, enhanced MODIS Airborne Simulator (eMAS) imaging scanner, and Cloud Radar System (CRS) on the ER-2 to validate NASA ICESat-2 atmospheric data products and validate ESA's recently launched EarthCARE lidar, radar, and spectrometer products.
NASA's Earth Science Division FireSense project focuses on delivering NASA's unique Earth science and technological capabilities to operational agencies, striving to address challenges in US wildland fire management. Together with agency, academic, and private partners, FireSense completed an airborne campaign in a wildfire smoke-impacted airshed in Missoula, MT on August 27-29, 2024. During the three-day campaign, a NASA Uninhabited Aerial System (UAS) team conducted eight data-collection flights, partnering these launches with weather balloon launches.
