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By NASA
Dr. Steven “Steve” Platnick stepped down from his role at NASA on August 8, 2025, after more than three decades of public service. Steve began his career at NASA as a physical scientist at Goddard Space Flight Center in 2002. He moved to the Earth Science Division in 2009, where he has served in various senior management roles, including as the Earth Observing System (EOS) Senior Project Scientist. In this role, he led the EOS Project Science Office and continued periodic meetings of the EOS Project Scientists, initiated by Michael King during his tenure. Steve expanded these meetings to include representatives of non-EOS Earth observing missions and representatives from Earth Science Mission Operations (ESMO). In addition, Steve was named Deputy Director for Atmospheres in the Earth Science Division in January 2015 and served in this position until July 2024.
Dr. Steve Platnick Image credit: NASA During his time at NASA, Steve played an integral role in the development, sustainability, and advancement of NASA’s Earth Observing System platforms. From January 2003 – February 2010, Steve served as Deputy Project Scientist for Aqua. In this role, he applied his expertise in theoretical and experimental studies of satellite, aircraft, and ground-based cloud remote sensing to improve algorithms to benefit the data gathered from remote observing systems.
Taking the Lead to Improve Algorithms
Steve was actively involved in the Moderate Resolution Imaging Spectroradiometer (MODIS) Science Team, serving as the MODIS Atmosphere Team Lead. Steve helped advance several key components of the MODIS instrument, which flies on NASA’s Terra and Aqua platforms. He led a team that enhanced, maintained, and evaluated MODIS algorithms that support the Level-2 (L2) Cloud Optical/Microphysical Properties components (e.g., COD06 and MYD06) for MODIS on Terra and Aqua. The algorithms were designed to retrieve thermodynamic phase, optical thickness, effective particle radius, and water path for liquid and ice clouds. The team’s work also contributes to L3 products that address cloud mask, aerosols, clouds, and clear sky radiance for data within 1° grids over one-day, eight-day, and one-month repeat cycles. Under Steve’s leadership, the team also developed L2 products (e.g., MODATML2 and MYDATML2) that include essential atmosphere datasets of samples collected at 5–10 km (3–6 mi) that is consistent with L3 products to ease storage requirements of core atmospheric data.
Steve is also a member of the Suomi-National Polar-orbiting Partnership (Suomi NPP) Atmosphere Team, working on operational cloud optical and microphysical products. In this role, he contributed to algorithm development and refinement for the Cloud Product. In particular, he helped address a critical gap in the Visible Infrared Imaging Radiometer Suite (VIIRS) spectral channel, which was not designed to collect information for carbon dioxide (CO2) slicing and water vapor data in the same way as MODIS. Steve and his colleagues developed a suite of L2 algorithms for the spectral channels that were common to both MODIS and VIIRS to address cloud mask and cloud optical/microphysical properties. Through these efforts, the project has established a continuous cloud data record gathered from both instruments from 2017 to the present.
Steve also participated in numerous other working groups during the past 30 years. He participated in the Global Energy and Water Exchanges (GEWEX) Cloud Assessment Working Group (2008–present), Arctic Radiation-Cloud-Aerosol-Surface Interaction Experiment (ARCSIX) Science Team (2023–present), ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) Earth–Venture Suborbital (EVS)-2 Science Team (2014–2023), Deep Space Climate Observatory (DSCOVR) Science Team (2014–present), Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) Science Team (2014–2023), PACE Science Definition Team, Deputy Chair (2011–2012), Glory Science Team (2010–2014) NASA Observations for Modeling Intercomparison Studies (obs4MIPs) Working Group (2011), Advanced Composition Explorer (ACE) Science Definition Team (2009–2011), and Geostationary Operational Environmental Satellites (GOES) R-series Advanced Baseline Imager (ABI) Cloud Team (2005–2009).
Steve has also participated in numerous major airborne field campaigns in various roles, including: GSFC Lidar Observation and Validation Experiment (GLOVE, 2025), PACE Postlaunch Airborne eXperiment (PAX, 2024), the Westcoast & Heartland Hyperspectral Microwave Sensor Intensive Experiment (WH2yMSIE, 2024), ORACLES Science Team (2015–2019), Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) Science Team (2011–2015), Tropical Composition, Cloud and Climate Coupling (TC4) Management Team (2007), Cirrus Regional Study of Tropical Anvils and Cirrus Layers – Florida Area Cirrus Experiment (CRYSTAL-FACE) Science Management Team (2002), Southern Africa Fire-Atmosphere Research Initiative (SAFARI, 2000), First ISCCP Regional Experiment (FIRE) Arctic Cloud Experiment (ACE) (1998), Mikulski Archive for Space Telescopes (MAST, 1994), and ACE (1992).
Supporting Earth Science Communications
Through his senior leadership roles within ESD Steve has been supportive of the activities of NASA’s Science Support Office (SSO). He has participated in many NASA Science exhibits at both national and international scientific conferences, including serving as a Hyperwall presenter numerous times. He has met with task leaders frequently and has advocated on behalf of the SSO to management at NASA Headquarters, GSFC, and Global Sciences & Technology Inc.
For The Earth Observer newsletter publication team in particular, Steve replaced Michael King as Acting EOS Senior Project Scientist in June 2008, taking over the authorship of “The Editor’s Corner” beginning with the May–June 2008 issue [Volume 20, Issue 3]. The Acting label was removed beginning with the January–February 2010 issue [Volume 22, Issue 1]. Steve has been a champion of continuing to retain a historical record of NASA meetings to maintain a chronology of advances made by different groups within the NASA Earth Science community. He was supportive of the Executive Editor’s efforts to create a series called “Perspectives on EOS,” which ran from 2008–2011 and told the stories of the early years of the EOS Program from the point of view of those who lived them. He also supported the development of articles to commemorate the 25th and 30th anniversary of The Earth Observer. Later, Steve helped guide the transition of the newsletterfrom a print publication – the November–December 2022 issue was the last printed issue – to fully online by July 2024, a few months after the publication’s 35th anniversary. The Earth Observer team will miss Steve’s keen insight, historical perspective, and encouragement that he has shown through his leadership for the past 85 issues of print and online publications.
A Career Recognized through Awards and Honors
Throughout his career, Steve has amassed numerous honors, including the Robert H. Goddard Award for Science: MODIS/VIIRS Cloud Products Science Team (2024) and the William Nordberg Memorial Award for Earth Science in 2023. He received the Verner E. Suomi Award from the American Meteorological Society (AMS) in 2016 and was named an AMS Fellow that same year.
Steve has received numerous NASA Group Achievement Awards, including for the Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP2Ex) Field Campaign Team (2020), Fire Influence of Regional to Global Environments and Air Quality (FIREX-AQ) Field Campaign Team (2020), ORACLES Field Campaign Team (2019), obs4MIPs Working Group (2015), SEAC4RS Field Campaign Team (2015), Advanced Microwave Scanning Radiometer for EOS (AMSR-E) Instrument Recovery Team (2013), Climate Absolute Radiance and Refractivity Observatory (CLARREO) Mission Concept Team (2012), Earth Science Constellation Red Team (2011), Science Mission Directorate ARRA Team (2011), TC4 Team (2009), MODIS Science Data Support Team (2007), Aqua Mission Team (2003), CRYSTAL-FACE Science Team (2003), and SAFARI 2000 International Leadership Team (2002).
Steve received two NASA Agency Honor Awards – the Exceptional Service Medal in 2015 and the Exceptional Achievement Medal in 2008. He was also part of the NASA Agency Team Excellence Award in 2017 for his work with the Satellite Needs Assessment Team. The Laboratory for Atmospheres honored him with the Best Senior Author Publication Award in 2001 and the Scientific Research Peer Award in 2005.
Steve received his bachelor’s degree and master’s degree in electrical engineering from Duke University and the University of California, Berkeley, respectively. He earned a Ph.D. in atmospheric sciences from the University of Arizona. He began his career at the Joint Center for Earth Systems Technology (JCET) at University of Maryland Baltimore County in 1996 as a research associate professor. He held this appointment until 2002. Steve has published more than 150 scholarly articles.
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By NASA
Roscosmos cosmonaut Kirill Peskov, left, NASA astronauts Nichole Ayers and Anne McClain, and JAXA (Japan Aerospace Exploration Agency) astronaut Takuya Onishi are seen inside the SpaceX Dragon spacecraft on the company’s recovery ship shortly after splashdown in the Pacific Ocean off the coast of San Diego, California, on Aug. 9, 2025.Credit: NASA/Keegan Barber After spending almost five months in space, NASA’s SpaceX Crew-10 astronauts will discuss their science mission aboard the International Space Station during a news conference at 4:15 p.m. EDT, Wednesday, Aug. 20, from the agency’s Johnson Space Center in Houston.
NASA astronauts Anne McClain and Nichole Ayers, and JAXA (Japan Aerospace Exploration Agency) astronaut Takuya Onishi will answer questions about their mission. The crew returned to Earth on Aug. 9.
Live coverage of the news conference will stream on the agency’s YouTube channel. Learn how to watch NASA content through a variety of additional platforms, including social media.
This event is open to media to attend in person or virtually. For in-person, media must contact the NASA Johnson newsroom no later than 12 p.m., Tuesday, Aug. 19, at: jsccommu@mail.nasa.gov or 281-483-5111. Media participating by phone must dial into the news conference no later than 10 minutes prior to the start of the event to ask questions. Questions also may be submitted on social media using #AskNASA. A copy of NASA’s media accreditation policy is available on the agency’s website.
The crew spent 146 days aboard the orbiting laboratory, traveling nearly 62,795,205 million miles and completing 2,368 orbits around Earth. While living and working aboard the station, the crew completed hundreds of science experiments and technology demonstrations. The latest NASA space station news, images, and features are available on Instagram, Facebook, and X.
NASA’s Commercial Crew Program has delivered on its goal of safe, reliable, and cost-effective transportation to and from the International Space Station from the United States through a partnership with American private industry. This partnership is opening access to low Earth orbit and the International Space Station to more people, more science, and more commercial opportunities. For almost 25 years, people have continuously lived and worked aboard the space station, advancing scientific knowledge and demonstrating new technologies that enable us to prepare for human exploration of the Moon as we prepare for Mars.
Learn more about NASA’s Commercial Crew Program at:
https://www.nasa.gov/commercialcrew
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Joshua Finch
Headquarters, Washington
202-358-1100
joshua.a.finch@nasa.gov
Courtney Beasley
Johnson Space Center, Houston
281-483-5111
courtney.m.beasley@nasa.gov
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Last Updated Aug 14, 2025 EditorJessica TaveauLocationNASA Headquarters Related Terms
Commercial Crew International Space Station (ISS) ISS Research Johnson Space Center View the full article
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By European Space Agency
Image: The development of ESA’s Earth Explorer FLEX mission has recently passed a significant milestone: the mission’s all-important instrument has been joined to its satellite platform. View the full article
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By NASA
Explore Hubble Science Hubble Space Telescope NASA’s Hubble Uncovers Rare… Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered AI and Hubble Science Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts Multimedia Images Videos Sonifications Podcasts e-Books Online Activities 3D Hubble Models Lithographs Fact Sheets Posters Hubble on the NASA App Glossary News Hubble News Social Media Media Resources More 35th Anniversary Online Activities 5 min read
NASA’s Hubble Uncovers Rare White Dwarf Merger Remnant
This is an illustration of a white dwarf star merging into a red giant star. A bow shock forms as the dwarf plunges through the star’s outer atmosphere. The passage strips down the white dwarf’s outer layers, exposing an interior carbon core. Artwork: NASA, ESA, STScI, Ralf Crawford (STScI) An international team of astronomers has discovered a cosmic rarity: an ultra-massive white dwarf star resulting from a white dwarf merging with another star, rather than through the evolution of a single star. This discovery, made by NASA’s Hubble Space Telescope’s sensitive ultraviolet observations, suggests these rare white dwarfs may be more common than previously suspected.
“It’s a discovery that underlines things may be different from what they appear to us at first glance,” said the principal investigator of the Hubble program, Boris Gaensicke, of the University of Warwick in the United Kingdom. “Until now, this appeared as a normal white dwarf, but Hubble’s ultraviolet vision revealed that it had a very different history from what we would have guessed.”
A white dwarf is a dense object with the same diameter as Earth, and represents the end state for stars that are not massive enough to explode as core-collapse supernovae. Our Sun will become a white dwarf in about 5 billion years.
In theory, a white dwarf can have a mass of up to 1.4 times that of the Sun, but white dwarfs heavier than the Sun are rare. These objects, which astronomers call ultra-massive white dwarfs, can form either through the evolution of a single massive star or through the merger of a white dwarf with another star, such as a binary companion.
This new discovery, published in the journal Nature Astronomy, marks the first time that a white dwarf born from colliding stars has been identified by its ultraviolet spectrum. Prior to this study, six white dwarf merger products were discovered via carbon lines in their visible-light spectra. All seven of these are part of a larger group that were found to be bluer than expected for their masses and ages from a study with ESA’s Gaia mission in 2019, with the evidence of mergers providing new insights into their formation history.
Astronomers used Hubble’s Cosmic Origins Spectrograph to investigate a white dwarf called WD 0525+526. Located 128 light-years away, it is 20% more massive than the Sun. In visible light, the spectrum of WD 0525+526’s atmosphere resembled that of a typical white dwarf. However, Hubble’s ultraviolet spectrum revealed something unusual: evidence of carbon in the white dwarf’s atmosphere.
White dwarfs that form through the evolution of a single star have atmospheres composed of hydrogen and helium. The core of the white dwarf is typically composed mostly of carbon and oxygen or oxygen and neon, but a thick atmosphere usually prevents these elements from appearing in the white dwarf’s spectrum.
When carbon appears in the spectrum of a white dwarf, it can signal a more violent origin than the typical single-star scenario: the collision of two white dwarfs, or of a white dwarf and a subgiant star. Such a collision can burn away the hydrogen and helium atmospheres of the colliding stars, leaving behind a scant layer of hydrogen and helium around the merger remnant that allows carbon from the white dwarf’s core to float upward, where it can be detected.
WD 0525+526 is remarkable even within the small group of white dwarfs known to be the product of merging stars. With a temperature of almost 21,000 kelvins (37,000 degrees Fahrenheit) and a mass of 1.2 solar masses, WD 0525+526 is hotter and more massive than the other white dwarfs in this group.
WD 0525+526’s extreme temperature posed something of a mystery for the team. For cooler white dwarfs, such as the six previously discovered merger products, a process called convection can mix carbon into the thin hydrogen-helium atmosphere. WD 0525+526 is too hot for convection to take place, however. Instead, the team determined a more subtle process called semi-convection brings a small amount of carbon up into WD 0525+526’s atmosphere. WD 0525+526 has the smallest amount of atmospheric carbon of any white dwarf known to result from a merger, about 100,000 times less than other merger remnants.
The high temperature and low carbon abundance mean that identifying this white dwarf as the product of a merger would have been impossible without Hubble’s sensitivity to ultraviolet light. Spectral lines from elements heavier than helium, like carbon, become fainter at visible wavelengths for hotter white dwarfs, but these spectral signals remain bright in the ultraviolet, where Hubble is uniquely positioned to spot them.
“Hubble’s Cosmic Origins Spectrograph is the only instrument that can obtain the superb quality ultraviolet spectroscopy that was required to detect the carbon in the atmosphere of this white dwarf,” said study lead Snehalata Sahu from the University of Warwick.
Because WD 0525+526’s origin was revealed only once astronomers glimpsed its ultraviolet spectrum, it’s likely that other seemingly “normal” white dwarfs are actually the result of cosmic collisions — a possibility the team is excited to explore in the future.
“We would like to extend our research on this topic by exploring how common carbon white dwarfs are among similar white dwarfs, and how many stellar mergers are hiding among the normal white dwarf family,” said study co-leader Antoine Bedrad from the University of Warwick. “That will be an important contribution to our understanding of white dwarf binaries, and the pathways to supernova explosions.”
The Hubble Space Telescope has been operating for more than three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
To learn more about Hubble, visit: https://science.nasa.gov/hubble
Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Related Images & Videos
White Dwarf Merger Illustration
This is an illustration of a white dwarf star merging into a red giant star. A bow shock forms as the dwarf plunges through the star’s outer atmosphere. The passage strips down the white dwarf’s outer layers, exposing an interior carbon core.
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Last Updated Aug 13, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Contact Media Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov
Ray Villard
Space Telescope Science Institute
Baltimore, Maryland
Bethany Downer
ESA/Hubble
Garching, Germany
Related Terms
Hubble Space Telescope Astrophysics Astrophysics Division Goddard Space Flight Center Stars The Universe White Dwarfs
Related Links and Documents
Science Paper: A hot white dwarf merger remnant revealed by an ultraviolet detection of carbon, PDF (23.45 MB)
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