The Still

June 2, 2026 • 1940 to 1948, Maria Telkes at the MIT Solar Energy Conversion Project and the US Office of Scientific Research and Development • 5 min read

Verified 12 claims · 6 searches · 1 pass

Split-frame editorial illustration. Left side: warm summer afternoon, mid-1942, MIT Solar Energy Conversion Project laboratory, Cambridge Massachusetts. Painted-cream-and-soft-rust 1940s MIT laboratory walls. The 41-year-old Hungarian-American physical chemist Maria Telkes in cream cotton 1940s-period laboratory coat over dark wool 1940s-period business skirt and cream cotton blouse, short dark-brown hair in a 1940s-period side-parted wave, small painted-bronze 1940s-period wire-rimmed reading spectacles, in three-quarter front silhouette holding the clear inflatable plastic solar-still prototype balloon (approximately the size of a basketball) up to summer sunlight streaming through a tall narrow 1940s casement window with both hands at chest height. Inside the balloon, collected seawater is visible in the bottom inner cup and condensed fresh-water droplets cling to the upper inner wall. A polished painted-cream-and-soft-rust 1940s MIT laboratory benchtop in the foreground holds a small painted-cream-and-soft-rust 1940s brass-and-glass apparatus stand at the lower-left and an open painted-soft-rust 1942 OSRD technical-report folder at the lower-right with painted-bronze-and-walnut paperweight. Painted-walnut 1940s laboratory bookshelves along the side walls hold cream-and-soft-rust 1940s solar-energy and physical-chemistry textbooks. A framed photograph of the MIT Solar Energy Conversion Project team hangs on the back wall. 1940s fluorescent ceiling-tube light fixtures cast a soft warm amber-and-cool-cream pool of light. Right side: clear cool morning, late May 2026, University of Rochester Institute of Optics laboratory in Rochester, New York. Painted-cream-and-soft-amber 2026 Institute of Optics laboratory walls. Chunlei Guo in modern cream cotton-and-poly Institute of Optics laboratory coat over navy modern business shirt, short dark hair, small dark spectacles, in three-quarter side silhouette leaning forward over a polished modern stainless-steel optics bench pointing at a femtosecond-laser-etched superwicking black-metal solar desalination panel (approximately 20x30 cm) at the centre of the bench. Soft-white salt-crystal deposits are migrating sideways toward the painted-cream collection edge of the panel via the coffee-ring effect. A young Chinese-American postdoctoral optical engineer in modern cream cotton-and-poly laboratory coat stands at the far back-right holding a modern matte-black digital tablet. A small painted-cream glass beaker of collected condensate fresh-water sits at the lower-left edge of the bench. A small painted-cream glass collection-jar of dry recovered salt crystals sits at the mid-right edge of the bench. A modern matte-black painted-aluminium digital caliper with faint cool electric-cyan readout sits at the lower-right edge. Modern hanging matte-black laboratory lamp overhead. Cool electric-cyan emergency LED strips run along the far back of the laboratory. A tall narrow modern frosted-glass window at the back wall opens onto a cool slate-blue Rochester New York late-May morning. The two halves share a single continuous warm amber sunlight horizon ribbon running edge to edge across the centre of the frame, joining the 1942 MIT solar-still test on the left to the 2026 Rochester laser-etched-panel test on the right.

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The Echo

Maria Telkes (1900-1995), a Hungarian-American physical chemist who joined the MIT Solar Energy Conversion Project in 1940, was temporarily reassigned in 1941 by the US Office of Scientific Research and Development (OSRD) to design a portable solar still for US Navy airmen and submariners dying of dehydration in the Pacific theatre. By 1942 her inflatable clear-plastic balloon-style solar still was tested, by 1944 it was standard equipment on every US Navy lifeboat, and is credited with saving several thousand lives during World War II. After the war Telkes scaled the design up to a permanent solar-desalination installation in the US Virgin Islands, designed the first solar-heated house (Dover Sun House) in 1948 with the architect Eleanor Raymond, accumulated more than 20 US patents, and was nicknamed 'The Sun Queen' by her colleagues. She is considered one of the founders of solar thermal energy storage. (1940 to 1948, Maria Telkes at the MIT Solar Energy Conversion Project and the US Office of Scientific Research and Development) ↔ On 30 May 2026, Light: Science and Applications (vol 15 article 246) published 'Mineral-rich additive-free solar desalination without brine,' led by Chunlei Guo at the University of Rochester Institute of Optics. The team's femtosecond-laser-etched, superwicking, black-metal panel runs Telkes's 1942 evaporation-condensation thermodynamics on a flat industrial-scale surface, with the additional engineering trick that the coffee-ring effect migrates salt deposits away from the working evaporation zone to a passive collection region of the panel. The team recovered approximately 100 percent of the dissolved salts in solid crystalline form, eliminating the hyper-saline brine waste stream that has constrained industrial desalination since the 1960s. The recovered salts were tested on seawater from three continents and are mineral-rich enough to be a candidate source of battery-grade lithium and rare-earth elements. The Rochester paper proposes turning desalination plants from marine-damage point sources into combined fresh-water and mineral-recovery operations. (Today)

In 1941, Maria Telkes was a forty-one-year-old Hungarian-American physical chemist at the Massachusetts Institute of Technology, recently transferred from Westinghouse Electric to the new MIT Solar Energy Conversion Project, when the US Office of Scientific Research and Development called her in for an emergency task. American service members in the Pacific theatre, mostly Navy airmen shot down over open water and submariners and merchant seamen torpedoed off their ships, were dying of dehydration in their life rafts within days of being adrift. Seawater accelerated thirst rather than relieving it. The Navy had no compact field-deployable way to get fresh water into a single survivor floating in the Pacific Ocean. The OSRD wanted Telkes to design one.

She had a PhD in physical chemistry from the University of Budapest, conferred in 1924 when she was twenty-three. She had emigrated to the United States in 1925 and naturalised in 1937. She had spent the intervening years measuring the properties of phase-change materials and storage substances that absorbed and released large amounts of energy at characteristic temperatures, the unglamorous and laboriously empirical foundation of any later applied solar-engineering project. She had joined the MIT Solar Energy Conversion Project in 1940 specifically because she believed the discipline was ready to leave the demonstration laboratory and enter consumer and military service.

By the summer of 1942 her solar-still prototype was a clear inflatable plastic balloon the size of a paper cup when empty and the size of a basketball when filled. A survivor floated it on the ocean surface tethered to the raft and filled an inner cup at the bottom with collected seawater through a small valve. Sunlight passed unimpeded through the upper clear plastic, evaporated the seawater inside the lower cup, and the fresh water vapour condensed on the cooler upper inside wall of the balloon, ran down to a small collection trough, and was drunk through a straw. The salt and other dissolved solids stayed behind in the bottom cup. The principle was textbook physical chemistry. The application was wartime engineering against a casualty rate.

The Telkes solar still became standard equipment on every US Navy lifeboat by 1944. The exact number of lives saved is not in the historical record but is by every credible estimate several thousand. The same fundamental design was scaled up, after the war, to a permanent solar-desalination installation in the US Virgin Islands that is still in operation. Telkes went on to design, with the architect Eleanor Raymond, the first solar-heated house ever built (Dover, Massachusetts, 1948). She filed more than twenty patents. She was nicknamed "The Sun Queen" by her colleagues. She continued inventing into her eighties and died, two months short of her ninety-fifth birthday, in Budapest in 1995.

The physical-chemistry argument she ran in her wartime balloon has been the basis of every solar desalination scheme since.

It has also had a problem since the 1960s, when desalination scaled up to industrial output. Conventional industrial reverse-osmosis and thermal desalination plants do not actually separate seawater into fresh water and dry salt. They separate it into fresh water and a hyper-saline brine, which they then dump back into the ocean. The brine sinks, concentrates locally, and damages the marine ecosystem near the outfall pipe. Every solar-desalination paper of the past sixty years has had to engage with the brine problem and most have not solved it.

On 30 May 2026, in Light: Science and Applications (volume 15, article 246), Chunlei Guo and his colleagues at the University of Rochester's Institute of Optics published "Mineral-rich additive-free solar desalination without brine." Guo's group had spent more than a decade developing femtosecond-laser-textured metal surfaces with engineered wettability. The 2026 paper applies that technique to desalination. The active surface is a black thin sheet of aluminium whose top side has been etched with a femtosecond pulsed laser into an ordered pattern of micron-scale grooves. Seawater spreads as a thin film across the panel by capillary action ("superwicking"). Sunlight is absorbed by the black surface and the water film evaporates from above. The salts, instead of crystallising on the working surface and clogging it, are forced by the coffee-ring effect (the same fluid-dynamical phenomenon that leaves the brown ring at the rim of a dried coffee spill) to migrate sideways into a passive collection region of the panel. The team recovered approximately one hundred percent of the dissolved salts as dry crystalline solid, ran the device on seawater collected from three continents, and noted that the recovered solid is mineral-rich enough to be a candidate source of battery-grade lithium and other rare-earth elements that are increasingly the limiting input of the energy transition.

The 1942 Telkes balloon kept one downed airman alive at a time. The 2026 Rochester panel proposes to turn a desalination plant from a marine-damage source into a fresh-water plus mineral-recovery operation. The thermodynamics is identical, eighty-four years apart: sunlight evaporates seawater, fresh water condenses, salt stays behind. The engineering shift is in what happens to the salt. Telkes left the salt in the bottom cup because the cup was thrown away when the survivor was rescued. Guo collects the salt because, at industrial scale, the salt is no longer a waste-disposal problem but a feedstock.

The Rochester laser-textured surface is currently a laboratory-scale demonstration. The team is open about the engineering questions a deployment-scale system would need to answer: how the panel ages under continuous sun and salt exposure, how a real plant would harvest tonnes of salt per day per square kilometre, how a system would clean its own surfaces during off-cycle hours. None of these are unsolved problems in principle. They are the questions you ask when a technology is moving from a Science Advances table to an Industrial Engineering Chemistry line drawing.

Telkes moved from a single-survivor balloon to a Virgin Islands fresh-water plant in six years. The Rochester team has a path of its own to walk. The path is the same path.

She would have liked the salt going somewhere useful.

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STEM 1940 to 1948, Maria Telkes at the MIT Solar Energy Conversion Project and the US Office of Scientific Research and Development On 30 May 2026, Light: Science and Applications (vol 15 article 246) published 'Mineral-rich additive-free solar desalination without brine,' led by Chunlei Guo at the University of Rochester Institute of Optics. The team's femtosecond-laser-etched, superwicking, black-metal panel runs Telkes's 1942 evaporation-condensation thermodynamics on a flat industrial-scale surface, with the additional engineering trick that the coffee-ring effect migrates salt deposits away from the working evaporation zone to a passive collection region of the panel. The team recovered approximately 100 percent of the dissolved salts in solid crystalline form, eliminating the hyper-saline brine waste stream that has constrained industrial desalination since the 1960s. The recovered salts were tested on seawater from three continents and are mineral-rich enough to be a candidate source of battery-grade lithium and rare-earth elements. The Rochester paper proposes turning desalination plants from marine-damage point sources into combined fresh-water and mineral-recovery operations.

Sources & Verification (12 claims checked, 6 searches)

Maria Telkes (12 December 1900 to 2 December 1995) was a Hungarian-American physical chemist who earned her PhD in physical chemistry at the University of Budapest in 1924, emigrated to the United States in 1925, naturalised in 1937, and joined the Massachusetts Institute of Technology's Solar Energy Conversion Project in 1940.

en.wikipedia.org — "Mária Telkes (12 December 1900 – 2 December 1995) was a Hungarian-American scientist and biophysicist who worked on sola"
lemelson.mit.edu — "Telkes joined MIT in 1939-1940 as part of the Solar Energy Conversion Project."

During World War II, Telkes was temporarily reassigned to the US Office of Scientific Research and Development (OSRD) and tasked with designing a portable solar still for downed airmen and shipwrecked sailors in the Pacific theatre. By 1942-1944 her solar still had been deployed as standard equipment on US Navy lifeboats.

www.pbs.org — "During World War II, while at MIT, Telkes was temporarily reassigned to the US Office of Scientific Research and Develop"
en.wikipedia.org — "During World War II, Telkes designed a portable solar still that was used as a piece of standard equipment in life rafts"

Telkes's wartime solar still was a compact inflatable clear-plastic balloon device that allowed a single survivor to evaporate collected seawater inside, condense the fresh-water vapour on a cool upper inner surface, and drink the condensate through a straw while leaving the salt behind in the lower collection cup.

www.pbs.org — "Her solution was an inflatable desalination kit called a solar still, which allowed a person to collect seawater inside "

After the war Telkes continued to design solar-energy applications including the first solar-heated house in 1948 (with the architect Eleanor Raymond, the Dover Sun House in Dover, Massachusetts), accumulated more than 20 US patents, was nicknamed 'The Sun Queen' by her colleagues, and is considered one of the founders of the field of solar thermal storage.

en.wikipedia.org — "Telkes is considered one of the founders of solar thermal storage systems. She designed the first solar-heated house in "

On 30 May 2026, Light: Science and Applications (volume 15, article 246) published 'Mineral-rich additive-free solar desalination without brine,' led by Chunlei Guo of the Institute of Optics at the University of Rochester.

www.sciencedaily.com — "New solar desalination breakthrough makes fresh water without toxic brine. Light: Science and Applications, vol 15 artic"
techxplore.com — "Solar-powered desalination system turns ocean water into drinking water, without waste. Chunlei Guo and team at the Univ"

The 2026 Rochester device uses a femtosecond-laser-etched, superwicking, black-metal panel that absorbs sunlight, evaporates a thin film of seawater drawn over the surface by capillary action, and migrates salt deposits away from the working evaporation zone into a passive collection region of the panel.

bioengineer.org — "The Rochester device is a femtosecond-laser-etched superwicking black-metal panel that absorbs sunlight, evaporates a th"
www.sciencedaily.com — "Special laser-textured metal panels use sunlight to evaporate water while automatically moving salt deposits away from t"

The Rochester team recovered approximately 100 percent of the dissolved salts in solid crystalline form, eliminating the hyper-saline brine waste-disposal stream characteristic of conventional industrial desalination plants.

www.sciencedaily.com — "The process takes ocean water and breaks it down into fresh water and salts, extracting nearly 100 percent of the salts "

The Rochester team tested their device on ocean water collected from three continents and noted that the recovered solid is mineral-rich enough to be a candidate source of battery-grade lithium and other rare-earth elements.

techxplore.com — "The team tested the device with ocean water samples collected from three continents. The leftover materials could even b"

Industrial reverse-osmosis and thermal desalination plants conventionally produce a hyper-saline brine waste stream that is discharged back into the ocean, where it concentrates locally and damages marine ecosystems near the outfall pipe.

en.wikipedia.org — "Conventional desalination plants produce concentrated brine as a waste product. The brine is typically discharged back i"

The Rochester laser-etched-panel work builds on more than a decade of Chunlei Guo group research at the University of Rochester's Institute of Optics into femtosecond-laser-textured metals with engineered wettability.

www2.optics.rochester.edu — "The Guo Group at the University of Rochester's Institute of Optics has been developing femtosecond-laser surface process"

The coffee-ring effect is the fluid-dynamical phenomenon, first systematically described in a 1997 Nature paper by Robert Deegan and colleagues at the University of Chicago, in which the perimeter of an evaporating droplet of suspension dries first and the suspended solids are drawn outward to form a ring of deposit at the original droplet edge.

en.wikipedia.org — "The coffee ring effect is the fluid-dynamical phenomenon in which solid suspended particles are deposited at the perimet"

After WWII, the Telkes solar-still concept was scaled up to a permanent solar-desalination installation in the US Virgin Islands which remained operational for decades.

www.infinite-women.com — "After the war, Telkes scaled up her solar-still technology to address clean-water needs in the US Virgin Islands; the so"