A photo of Mars and Venus.

New Insights into Mars and Venus

 

By Christopher Crockett and Stuart Wolpert

 

David Paige is deputy principal investigator of Radar Imager for Mars’ Subsurface Experiment, or RIMFAX, one of seven instruments on NASA’s Perseverance rover.

About the size of a car, the Perseverance rover landed on Mars on Feb. 18. Over the next two years it will explore Jezero Crater in Mars’ northern hemisphere for signs of ancient life and new clues about the planet’s climate and geology.

Among other tasks, Perseverance will collect rock and soil samples in tubes that a later spacecraft will bring back to Earth. The experiments will lay the groundwork for future human and robotic exploration of Mars. RIMFAX will probe beneath the planet’s surface to study its geology in detail.

“Jezero Crater is a very interesting location on Mars because it looks like there was once a lake inside the crater, and that a river flowed into the lake and deposited sediments in a delta,” Paige said. “We plan to explore the delta to learn more about Mars’ climate history, and maybe something about ancient Martian life. What we’ll be able to see once we start roving and what we will actually learn is anybody’s guess.”

RIMFAX will provide a highly detailed view of subsurface structures and help find clues to past environments on Mars, including those that may have provided the conditions necessary for sup-porting life, he said.

Paige emphasized that RIMFAX is an experiment. “We’ve never tried using a ground-penetrating radar on Mars before, so we can’t really predict what types of subsurface structures we might be able to see. But we have done some fairly extensive field testing of RIMFAX on Earth to learn how to use it and how to interpret the data. Here, ground-penetrating radars can be very useful for clarifying subsurface geology.”

Is he hopeful of finding water, or evidence of water, beneath the planet’s surface?

“There are all kinds of evidence for past liquid water all over Mars,” Paige said. “At Jezero, there must have been a lot of water at some point, but we don’t expect that the ground beneath the rover will still be wet. Mars today is a very cold place, and any water in the shallow subsurface should be frozen at Jezero. What we’re interested in finding are geologic features that wouldn’t be expected to form under present climatic conditions, as those would be especially interesting targets to search for signs of past life.”

UCLA College graduate students Max Parks and Tyler Powell in Earth, Planetary, and Space Sciences are part of the science team, and Mark Nasielski, a UCLA graduate student in electrical engineering, is part of the operations team.

VENUS IS AN ENIGMA

Venus is the planet next door yet reveals little about itself. An opaque blanket of clouds smothers a harsh landscape pelted by acid rain and baked at temperatures that can liquify lead.

Now, new observations from the safety of Earth are lifting the veil on some of Venus’ most basic properties. By repeatedly bouncing radar off the planet’s surface over the last 15 years, a UCLA-led team has pinned down the precise length of a day on Venus, the tilt of its axis and the size of its core — findings published in the journal Nature Astronomy.

“Venus is our sister planet, and yet these fundamental properties have remained unknown,” said professor Jean-Luc Margot, who led the research.

Earth and Venus have a lot in common: Both are rocky planets and have nearly the same size, mass and density. And yet they evolved along wildly different paths. Fundamentals such as how many hours are in a Venusian day provide critical data for understanding the divergent histories of these neighboring worlds.

Changes in Venus’ spin and orientation reveal how mass is spread out within. Knowledge of its internal structure, in turn, fuels insight into the planet’s formation, its volcanic history and how time has altered the surface. Plus, without precise data on how the planet spins, any future landing attempts could be off by as much as 30 kilometers.

The new radar measurements show that an average day on Venus lasts 243.0226 Earth days — roughly two-thirds of an Earth year. What’s more, the rotation rate of Venus is always changing: A value measured at one time will be a bit larger or smaller than a previous value. The team estimated the length of a day from each of the individual measurements, and they observed differences of at least 20 minutes.

Venus’ heavy atmosphere is likely to blame for the variation.

The UCLA-led team also reports that Venus tips to one side by precisely 2.6392 degrees (Earth is tilted by about 23 degrees), an improvement on the precision of previous estimates by a factor of 10. The repeated radar measurements further revealed the glacial rate at which the orientation of Venus’ spin axis changes, much like a spinning top. On Earth, this “precession” takes about 26,000 years to cycle around once. Venus needs a little longer: about 29,000 years.

The team has turned its sights on Jupiter’s moons Europa and Ganymede. Many researchers strongly suspect that Europa hides a liquid water ocean beneath a thick shell of ice. Ground-based radar measurements could fortify the case for an ocean and reveal the thickness of the ice shell.

And the team will continue bouncing radar off Venus. With each radio echo, the veil over Venus lifts a little bit more, bringing our sister planet into ever sharper view.

This research was supported by NASA, the Jet Propulsion Laboratory and the National Science Foundation.

 

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Photo of Richard Kaner, with Maher El-Kady, holding a replica of an energy storage and conversion device the pair developed.

Creating electricity from snowfall and making hydrogen cars affordable

Photo of Richard Kaner, with Maher El-Kady, holding a replica of an energy storage and conversion device the pair developed.

Richard Kaner, with Maher El-Kady, holding a replica of an energy storage and conversion device the pair developed. Photo credit: Reed Hutchinson

Professor Richard Kaner and researcher Maher El-Kady have designed a series of remarkable devices. Their newest one creates electricity from falling snow. The first of its kind, this device is inexpensive, small, thin and flexible like a sheet of plastic.

“The device can work in remote areas because it provides its own power and does not need batteries,” said Kaner, the senior author who holds the Dr. Myung Ki Hong Endowed Chair in Materials Innovation.“It’s a very clever device — a weather station that can tell you how much snow is falling, the direction the snow is falling and the direction and speed of the wind.”

The researchers call it a snow-based triboelectric nanogenerator, or snow TENG. Findings about the device are published in the journal Nano Energy.

The device generates charge through static electricity. Static electricity occurs when you rub fur and a piece of nylon together and create a spark, or when you rub your feet on a carpet and touch a doorknob.

“Static electricity occurs from the interaction of one material that captures electrons and another that gives up electrons,” said Kaner, who is also a distinguished professor of chemistry and biochemistry, and of materials science and engineering, and a member of the California NanoSystems Institute at UCLA. “You separate the charges and create electricity out of essentially nothing.”

Snow is positively charged and gives up electrons. Silicone — a synthetic rubber-like material that is composed of silicon atoms and oxygen atoms, combined with carbon, hydrogen and other elements — is negatively charged. When falling snow contacts the surface of silicone, that produces a charge that the device captures, creating electricity.

“Snow is already charged, so we thought, why not bring another material with the opposite charge and extract the charge to create electricity?” said El-Kady, assistant researcher of chemistry and biochemistry.

“After testing a large number of materials including aluminum foils and Teflon, we found that silicone produces more charge than any other material,” he said.

Approximately 30 percent of the Earth’s surface is covered by snow each winter, El-Kady noted, during which time solar panels often fail to operate. The accumulation of snow reduces the amount of sunlight that reaches the solar array, limiting their power output and rendering them less effective. The new device could be integrated into solar panels to provide a continuous power supply when it snows.

The device can be used for monitoring winter sports, such as skiing, to more precisely assess and improve an athlete’s performance when running, walking or jumping, Kaner said. It could usher in a new generation of self-powered wearable devices for tracking athletes and their performances. It can also send signals, indicating whether a person is moving.

The research team used 3-D printing to design the device, which has a layer of silicone and an electrode to capture the charge. The team believes the device could be produced at low cost given “the ease of fabrication and the availability of silicone,” Kaner said.

New device can create and store energy

Kaner, El-Kady and colleagues designed a device in 2017 that can use solar energy to inexpensively and efficiently create and store energy, which could be used to power electronic devices, and to create hydrogen fuel for eco-friendly cars.

The device could make hydrogen cars affordable for many more consumers because it produces hydrogen using nickel, iron and cobalt — elements that are much more abundant and less expensive than the platinum and other precious metals that are currently used to produce hydrogen fuel.

“Hydrogen is a great fuel for vehicles: It is the cleanest fuel known, it’s cheap and it puts no pollutants into the air — just water,” Kaner said. “And this could dramatically lower the cost of hydrogen cars.”

The technology could be part of a solution for large cities that need ways to store surplus electricity from their electrical grids. “If you could convert electricity to hydrogen, you could store it indefinitely,” Kaner said.

Kaner is among the world’s most influential and highly cited scientific researchers. He has also been selected as the recipient of the  American Institute of Chemists 2019 Chemical Pioneer Award, which honors chemists and chemical engineers who have made outstanding contributions that advance the science of chemistry or greatly impact the chemical profession.

Co-authors on the snow TENG work include Abdelsalam Ahmed, who conducted the research while completing his Ph.D. at the University of Toronto, and Islam Hassan and Ravi Selvaganapathy at Canada’s McMaster University, as well as James Rusling, who is the Paul Krenicki professor of chemistry at the University of Connecticut, and his research team.

More devices designed to solve pressing problems

Last year, Kaner and El-Kady published research on their design of the first fire-retardant, self-extinguishing motion sensor and power generator, which could be embedded in shoes or clothing worn by firefighters and others who work in harsh environments.

Kaner’s lab produced a separation membrane that separates oil from water and cleans up the debris left by oil fracking. The separation membrane is currently in more than 100 oil installations worldwide. Kaner conducted this work with Eric Hoek, professor of civil and environmental engineering.