The Earth Observer Editor’s Corner: Jan – Feb 2024

The Earth Observer continues to work on its transition to our new website. Implementing a completely new set-up is not without challenges and has taken a bit longer than anticipated. The plan is to have the site fully operational soon – current estimate is no earlier than (NET) June 2024. In the meantime, to reduce a gap between our continuous 35-year run of PDF issues and the rollout of the new website, the newsletter team decided to release one final PDF issue.

The launch of the new website for The Earth Observer is far from the only Earth Science launch we have to discuss. In our last issue we announced that the Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission had successfully launched from Kennedy Space Center in the early morning of February 8, 2024. Just 63 days later, data from NASA’s newest Earth-observing satellite became available to the public – see Figure. These data will extend and improve upon NASA’s 20+ years of global satellite observation of our living oceans, atmospheric aerosols, and clouds, and initiate an advanced set of climate-relevant data records. Ultimately, PACE is the first mission to provide measurements that will enable prediction of the “boom–bust” cycle of fisheries, the appearance of harmful algae, and other factors that affect commercial and recreational industries. PACE also observes aerosols that influence air quality as well as the absorption and reflection of sunlight by both aerosols and clouds, which in turn impacts the radiation budget.

Along with the first image release, PACE produced a gallery of first light imagery to commemorate this initial data release and celebrate and highlight the advanced capabilities of PACE. Using the Ocean Color Instrument (OCI) aboard PACE, Joseph Knuble [NASA’s Goddard Space Flight Center (GSFC)—OCI Lead Instrument Systems Engineer] created a series of images using only 3 of 288 hyperspectral wavelengths (e.g., visible Red–Green–Blue) provided by the state-of-the-art sensor. Congratulations to the entire PACE team on the mission’s progress and these first light images. 

In addition to PACE, the launch of NASA’s Polar Radiant Energy in the Far-InfraRed Experiment (PREFIRE) is imminent. Selected through NASA’s Earth Venture program, PREFIRE will make the first full spectral measurements of Far InfraRed (FIR) radiation, revealing the full spectrum of Arctic radiant energy. Filling in this missing data from Earth’s polar regions will help us understand how much of Earth’s heat is lost to space. Analysis of PREFIRE’s measurements will inform climate and ice models, providing better projections of how a warming world will affect sea ice loss, ice sheet melt, and sea level rise. The mission is designed for a pair of two 6U CubeSats to measure this little-studied portion of emitted radiant energy for clues about a warming Arctic – the region that behaves like our planet’s thermostat, as it regulates the climate by venting excess energy received in the tropics. 

The first PREFIRE CubeSat launch is scheduled NET May 22, 2024, aboard an Electron rocket to be launched from Rocket Lab’s Launch Complex 1 in Māhia, New Zealand, with the launch of the other PREFIRE CubeSat to take place within three weeks of the first via the same rocket launched from the same location. These two small spacecrafts will occupy two different 525 km altitude (326 mi), near polar, sun synchronous (97.5 deg inclination) orbits. Each CubeSat is equipped with a heritage miniaturized infrared spectrometer, covering the 3–54 μm wavelength region at approximately 0.84 μm spectral sampling, operating for about one seasonal cycle (about a year) with diurnal subsampling. 

PREFIRE’s Thermal IR Spectrometer (TIRS) instrument is equipped with flight-proven hardware and design, originating from both the Mars Climate Sounder (MCS) aboard the Mars Reconnaissance Orbiter (MRO), which was designed to map the three-dimensional structure of temperature, dust, water ice, and water vapor in the atmosphere of Mars, as well as Diviner, an instrument flying aboard NASA’s Lunar Reconnaissance Orbiter (LRO), designed to measure surface temperatures on the Moon. PREFIRE has been jointly developed by NASA and the University of Wisconsin-Madison, with team members from the universities of Michigan and Colorado. 

NASA recently announced the selection of six new Earth Venture Suborbital (EVS) missions that will deploy at various times from 2026 to 2029. These missions were from the EVS-4 Announcement of Opportunity. They are all aircraft investigations that include domestic and international studies of fire-induced clouds, Arctic coastal change, air quality, landslide hazards, shrinking glaciers, and emissions from agricultural lands. NASA’s suite of airborne missions complement what scientists can see from orbit, measure from the ground, and simulate in computer models. 

Three lead investigators were chosen for each mission, with at least one required to be an early career scientist. Full staffing of the science teams and selection of complementary instruments will be competed in the coming months. A recent NASA press release provides more details on each EVS-4 mission and names the Principal Investigators. Congratulations to all the teams – especially the early career investigators – who will provide leadership for these suborbital investigations. 

Turning to an update on a current Earth science mission, NASA’s GRACE Follow-On (G-FO) mission continues to perform well. The primary mission objective for G-FO is to provide continuity for the monthly GRACE mass-change observations [2002–2017] via its Microwave Interferometer (MWI) intersatellite range-change observations. The twin G-FO satellites (launched in May 2018) have been tracking Earth’s water movements and global surface mass changes that arise from climatic, anthropogenic, and tectonic changes. As of April 2024, the G-FO project team has processed and released 65 monthly mass change and gravity fields – the most recent being for February 2024 (at the time of writing). G-FO also enables new insights into variations of ice sheet and glacier mass, land water storage, as well as changes in sea level and ocean currents. 

G-FO was among the missions that went through the 2023 NASA Earth Science Senior Review. The G-FO proposal submitted for the Senior Review advocated extending mission operations until 2026 and received an Excellent score. However, in light of overall budget constraints at NASA, the G-FO project’s budget will be reduced (compared to the previous baseline) by 15% in fiscal year (FY) 2024, and 24% in FY 2025 and 2026. Despite these reductions, the G-FO team remains confident in its ability to continue delivering high-value and high-impact science data products by prioritizing science operations management and data latency over data reprocessing campaigns. 

In terms of a “follow-on” to G-FO, the 2017 NASA Earth Science Decadal Survey Report highlighted mass-transport monitoring through gravity change, or Mass Change, as one of five designated observables (i.e., top priorities for study) in Earth observations for the next decade in collaboration with international partners. Since then, NASA, the German Aerospace Center (DLR), and other partners have been working on Mass Change mission concepts. In late 2023, NASA and DLR signed an agreement to continue their more than two decades of collaboration on a Mass Change mission that will be known as GRACE–Continuity, or GRACE-C. Like its predecessors, GRACE-C will be a single satellite pair, but this time the precise gravity measurements will be obtained using a fully redundant Laser Ranging Interferometer (technology that was demonstrated on G-FO) in a polar orbit at 500 km (~311 mi) altitude. Critically, to avoid a data gap after G-FO, a launch date of no later than 2028 is targeted for GRACE-C.

It is bittersweet to report the end of the CloudSat mission after nearly two decades of providing never-before-seen details of cloud vertical structure. As can be said of many NASA Earth science missions, CloudSat was an overachiever. Originally proposed as a 22-month mission, the spacecraft was recently decommissioned in March 2024 after almost 18 years of observations. The spacecraft, having reached the end of its lifespan and no longer able to make regular observations, was lowered into a graveyard orbit that will result in its eventual disintegration in the atmosphere. When launched in 2006, the mission’s Cloud Profiling Radar (CPR) was the first 94 GHz wavelength (W-band) radar to fly in space. A thousand times more sensitive than typical ground-based weather radars, data from CPR has informed thousands of research publications and continues to help scientists make key discoveries, including the amount of ice and liquid water contained within clouds globally and the radiative implications of these amounts. Congratulations to the entire CloudSat team, past and present, especially PI Graeme Stephens and Project Manager Deb Vane [both at NASA/Jet Propulsion Laboratory]. To learn more, see the news release about the end of CloudSat that was released on April 23. 

Closer to the ground, NASA’s Earth Science Technology Office (ESTO), which manages the development of technologically advanced, reliable, and cost-effective components, instruments, and information systems that help NASA meet its science objectives, has reached a milestone: 25 years of managing the development of more than 1,100 new technologies for future science measurements. This diverse, forward-looking portfolio has nurtured new Earth-observing capabilities, informed Decadal Surveys and strategic planning, and generated numerous infusions and spinoffs. At least 269 ESTO technologies have been infused into Earth science missions, science campaigns, or other operational or commercial activities over the past two and a half decades. My congratulations to the entire ESTO team for this significant accomplishment.

In other news, the Terra/Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) Science and Instrument Teams have been selected as the recipient of the 2023 American Astronautical Society (AAS) Earth Science and Applications Award. The award is presented annually for an outstanding achievement in Earth or environmental sciences. The team is being recognized for development of a pioneering instrument onboard NASA’s Terra and Aqua satellites, which has revolutionized our understanding of Earth’s dynamic processes and global environmental changes. My sincere congratulations to the Terra and Aqua MODIS teams. 

Finally, NASA had another excellent exhibit at the American Geophysical Union (AGU) Fall Meeting in San Francisco, CA this past December. NASA’s multidecadal exhibit presence at the annual AGU Fall Meeting has been coordinated for many years by GSFC’s Science Support Office (SSO). Nearly 40 NASA projects and missions had hands-on activities within the perimeter of the NASA Science exhibit – from the James Webb Space Telescope to the Airborne Science Fleet. The NASA Hyperwall, a video wall used for visual-forward science storytelling, served as the backdrop for 57 Hyperwall Stories throughout the meeting, including 8 presentations delivered by the 2023 winners of the NASA-funded AGU Michael H. Freilich Student Visualization Competition. The exhibit also featured 44 tech demos throughout the week, covering a wide range of hands-on introductions to everything from the capabilities of the OpenSpace data visualization software to the scientific applications of augmented reality.

Steve Platnick
EOS Senior Project Scientist