Hubble Survey Sets Up Roman’s Future Look Near Milky Way’s Center - UNIVERSE

This VISTA VVV Survey image shows the galactic bulge near Sagittarius A*, the supermassive black hole at the Milky Way’s center. A region planned for observation by NASA’s Nancy Grace Roman Space Telescope is outlined. This area has been observed by NASA’s Hubble Space Telescope.

Image: NASA, Alyssa Pagan (STScI); Acknowledgment: VISTA, Dante Minniti (UNAB), Ignacio Toledo (ALMA), Martin Kornmesser (ESO)

The Milky Way’s galactic bulge, the bulbous region that surrounds the galactic center, contains a dense collection of stars, planets, and other free-floating objects. This region has been studied for decades with numerous ground-based and space-based telescopes, including NASA’s Hubble and James Webb space telescopes. Soon, NASA’s Nancy Grace Roman Space Telescope will be the first to make studying the galactic bulge a part of its core science objectives, building on the data collected from all observatories before it. Roman’s field of view will cover more area at a far faster cadence than previous space telescopes, allowing it to survey millions of stars and find thousands of new exoplanets.

To support Roman in characterizing numerous stars and planets, astronomers sought to use Hubble to observe many of the same areas of the galactic bulge that Roman will observe in its core Galactic Bulge Time-Domain Survey. By comparing Hubble data taken months or years earlier to new Roman data, astronomers will be better able to interpret Roman’s forthcoming observations. The Roman telescope team is targeting as soon as early September 2026 for launch.

“A top priority of our Hubble survey is to cover as much sky area as possible,” said Sean Terry, project lead and assistant research scientist from the University of Maryland, College Park and NASA’s Goddard Space Flight Center in Greenbelt.

A paper about the team’s work published May 11, 2026 in the Astrophysical Journal.

‘Small’ lenses, large discoveries

Many planetary systems within the Milky Way evolve much like our solar system did, beginning with the collapse of a cosmic gas cloud, the growth of a star, and the formation of surrounding planets. However, in some systems, different events can result in a planet being ejected from the system where it formed. Hundreds of these “rogue planets” will be detected by Roman’s Galactic Bulge Time-Domain Survey, in addition to previously unseen, isolated neutron stars, and even black holes with masses similar to our Sun.

This survey consists of six 72-day observing seasons during which Roman will take a snapshot every 12 minutes of a large portion of the bulge (approximately 1.7 square degrees of the region, or the area of 8.5 full moons). While it will detect a variety of targets, the survey is optimized to look for a specific type of event known as microlensing.

Microlensing events, a type of gravitational lensing event, occur when the light from a more distant object is warped by the mass of a closer object along the line of sight. These events occur on a much smaller scale than larger lensing events (on the order of individual stars instead of galaxies or galaxy clusters) and allow us to search for exoplanets between us and the densely packed stars within the galactic bulge.

“The great thing about microlensing is that we’ll be able to do a complete census of objects as small as Mars that are moving between us and these fields in the bulge, no matter what it is,” said co-author Jay Anderson of the Space Telescope Science Institute in Baltimore.

For Roman, from Hubble

When a telescope observes a lensing object, such as a bright star, aligning with a star in the galactic bulge, it can be difficult for astronomers to decipher which of the two the starlight comes from. Therefore, timing is a key consideration. If astronomers can identify light sources separately before a microlensing event occurs, it becomes far easier to disentangle them.

To collect this pre-Roman data, astronomers used the Hubble Space Telescope to conduct a large-scale survey, which began in the spring of 2025, covering much of the same area that Roman will observe in the Galactic Bulge Time-Domain Survey. The size of this program is even larger than two previous surveys (each around 0.5 square degrees) that led to Hubble’s largest mosaic, that of our neighboring Andromeda galaxy, which took over 10 years to assemble.

“The main goal of these observations is to be able to identify objects that participate in lensing events during the Roman survey, catching them before they undergo the lensing event,” said Anderson. “When, in a couple of years, an event happens during Roman's long stare at the field, we can go back and say, ‘This was a red star, this was a blue star, and the event happened when the red star went in front of the blue star.’”

The data from Hubble also will help shape the analysis of the lensing objects themselves. The microlensing event itself measures only a ratio of the masses of a host star and its planet. With data from stars before or after their microlensing events, however, scientists would be able to measure the stars’ individual masses, echoing the way Hubble previously determined the mass of a star and its planet in the Milky Way. This method turns a more opaque measurement of the relationship between a star and its planet into one far more certain. 

“Instead of estimating a mass ratio of a planet that's orbiting a star, we can say that we're confident it's a Saturn-mass planet orbiting a star that's 0.8 solar masses, for example,” Terry said. “So with the help of precursor imaging from Hubble you can hope to get direct measurements of the masses as opposed to indirect mass ratios.”

Next leap in magnitude

While exoplanet discovery is a large part of Roman’s Galactic Bulge Time-Domain Survey, observing such a large area with Hubble also can help identify areas of extinction, dense pockets of dust and gas that absorb or scatter light, allowing us to create maps detailing where we can see stars and where we can’t.

Hubble’s survey also has provided the crucial beginning of a brand-new catalog of stars, which will help astronomers characterize the host stars of exoplanets discovered by Roman. The research team predicts Roman will add to Hubble’s star catalog by an order of magnitude.

“This Hubble survey will build a catalog of 20 to 30 million point sources,” said Terry. “But, by the end of the Galactic Bulge Time-Domain Survey, Roman may measure about 200 to 300 million, and it will produce, essentially, some of the deepest images ever taken of any part of the sky.”

The data from the most recent Hubble survey is available in the Mikulski Archive for Space Telescopes. 

Source: Hubble Survey Sets Up Roman’s Future Look Near Milky Way’s Center - NASA Science    

Solar-powered gel pulls drinking water from the air - Engineering - Energy & Green Tech

The salt in the hydrogel crystallizes when dry. Credit: Andrew Brodhead

Scientists in recent years have sought to efficiently draw moisture from ambient air and condense it into potable water using materials made of salt and absorbent polymers. But these materials, known as hydrogels, until now have degraded too quickly to be practical or cost-effective.

Researchers have now discovered a way to harvest water from air using solar power and a hydrogel that lasts for eight months or more. Attached to metal coated to prevent corrosion, the long-lasting material can produce water at low cost almost anywhere.

"There are a lot of people who don't have access to water or have to walk hundreds of hours per year to procure water," said Carlos Diaz-Marin, an assistant professor of energy science and engineering in the Stanford Doerr School of Sustainability and co-lead author of the research published May 7 in Nature Communications. "There are also very water-intensive industries like semiconductor manufacturing and data centers that are putting even more pressure on water systems. We believe this could potentially be a way to provide additional water resources."

"These new hydrogels are exceptionally exciting because they give us a way to produce potable drinking water in really extreme conditions," said co-lead author Chad Wilson, who worked on the hydrogel as a graduate student at the Massachusetts Institute of Technology.

Until now, materials known as hydrogels have degraded too quickly to be practical or cost-effective for producing clean drinking water. Credit: Andrew Brodhead

In previous work, published in 2025, the team brought a hydrogel device—a square about cookie-sheet-size with a metal frame—to Chile to test it in the Atacama Desert, one of the world's driest places. They used a hydrogel made of the superabsorbent salt lithium chloride and a polymer commonly used in diapers, polyacrylamide.

Even in the Atacama Desert's parched environment, the hydrogel filled up with water overnight. The researchers used a sheet of aluminum painted black to absorb the sun's heat and heat up the hydrogel. As it warmed during the day, the hydrogel released water as vapor, which could then be condensed back into liquid water and collected for drinking. The gel proved highly absorbent, holding between two to four times its weight in water.

While the gel was effective at attracting moisture even where it's scarce, the researchers soon found a problem. It lasted only about 30 cycles of filling up and releasing water before it degraded. This is a problem not only for producing water cheaply, but also for safety. "Any degradation could make either the salt or the polymer go into the condenser," said Diaz-Marin. "That would basically destroy the potability of the water."

More than half a million U.S. households lack access to running water. One in four people globally lack access to safe drinking water.

Building a stable sorbent

Through lab experiments over the past four years, the researchers have investigated how the hydrogel breaks down. They found that problems arise from the gel's contact with a metal surface, such as the painted foil in the Atacama Desert experiment. The metal casing is key to powering the water-harvesting process with heat from the sun, but it also releases ions that form radicals in the hydrogel and attack the polymer's long chains. The gel turns to goo as bits of polymer leach into the water.

"The radicals are very efficient at eating the polymer away," said Diaz-Marin. "To our knowledge, nobody had thought of durability and degradation of these materials, despite it being a critical parameter for water production."

The researchers tested interventions to block the metal ions. When they applied an anti-corrosion coating to the metal, the hydrogel's lifespan dramatically extended. In one test, the hydrogel remained stable for more than eight months while kept at 167°F, a temperature meant to stress-test the material under extreme conditions. The researchers also found the hydrogel on coated metal remained stable for more than 190 water-harvesting cycles.

Durable hydrogels, cheap water

This level of durability advances the hydrogel toward producing water at a competitive cost. The improvements "could let us get to a point where we produce water at maybe one cent per liter," said Diaz-Marin. This would be about 1% of the cost of bottled water and about 10 times the rate U.S. households pay for tap water. "We see a path to this technology to perhaps even being competitive with tap water."

At the right price, a future hydrogel-based water system could bring potable water to rural communities facing water shortages in arid inland regions, where other technologies such as desalination are not an option. Since it's solar-powered, it doesn't need a grid connection and would have a minimal environmental footprint compared to water that needs to be pumped or trucked in.

It's not ready to supply communities just yet, but the team is optimistic. Diaz-Marin and his students are now working to further improve efficiency and cost. Their current design can produce up to two liters, or a little over half a gallon, of water daily with a thin layer of material spread over a panel roughly the size of a bath towel. That's around the amount of water generally needed per person per day to maintain basic health during emergencies.

Diaz-Marin said his goal is to increase the output to five liters daily. "Especially being at Stanford," he said, "I could see us translating this into the world either by a startup or licensing it." In the not-so-distant future, we could be sipping sky water.

Provided by Stanford University 

by Ula Chrobak, Stanford University

edited by Lisa Lock, reviewed by Robert Egan 

Source: Solar-powered gel pulls drinking water from the air