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Ed Stone, JPL director and top scientist on Voyager mission, dies at 88



Ed Stone, JPL director and top scientist on Voyager mission, dies at 88

Ed Stone, the scientist who guided NASA’s breakthrough Voyager mission to the outer planets for 50 years and led the Jet Propulsion Laboratory when it landed its first rover on Mars, died Tuesday. He was 88.

A physicist who got in on the ground floor of space exploration, Stone played a leading role in NASA missions to Mars, Jupiter, Saturn, Uranus and Neptune. The discoveries made under his watch revolutionized scientists’ understanding of the solar system and fueled humanity’s ambition to explore distant worlds.

Carolyn Porco, who worked on imaging on JPL’s Voyager and Cassini missions, called Stone “a thoroughly lovely man” who was “as close to perfect as a project scientist could ever be.”

“When two science teams were in contention over some spacecraft resource, and Ed had to decide between the two, even the guy who lost went away thinking, ‘Well, if this is what Ed has decided, then it must be the right answer,’” Porco said by email Tuesday. “I feel blessed to have known Ed. And like many people today, I’m very sad to know he’s gone.”

Stone was a 36-year-old Caltech physics professor in 1972 when he was asked to serve as chief scientist for an audacious plan to send a pair of spacecraft to explore the solar system’s four giant planets for the first time.


It was the opportunity of a lifetime, but he wasn’t sure he wanted the gig.

“I hesitated because I was a fairly young professor at that point. I still had a lot of research I wanted to do,” he recalled 40 year later.

He took it anyway, and from the mission’s first encounter with Jupiter in 1979 to its final flyby of Neptune in 1989, Stone became the scientific face of the Voyager mission. He guided the science agenda and helped the public make sense of revolutionary images and data not just from Jupiter, Saturn, Uranus and Neptune, but from many of their fascinating moons.

Stone and his more than 200 science collaborators were the first to discover lightning on Jupiter and volcanoes on its moon Io. They spotted six never-before-seen moons around Saturn and found evidence of the largest ocean in the solar system on Jupiter’s moon Europa, as well as geysers on Neptune’s moon Triton.

“It seemed like everywhere we looked, as we encountered those planets and their moons, we were surprised,” Stone told the Los Angeles Times in 2011. “We were finding things we never imagined, gaining a clearer understanding of the environment Earth was part of. I can close my eyes and still remember every part of it.”


The Voyager 1 spacecraft became the first manmade object to reach interstellar space in 2012, and Voyager 2 followed suit in 2018.

Stone, pictured with a model of the Voyager spacecraft, said the discovery of volcanoes on Io was a highlight of the mission.


The twin probes continue to send weekly communications to Earth from interstellar space. Stone retired in 2022 on the mission’s 50th anniversary.


“A part of Ed lives on in the two Voyager spacecraft. The fingerprints of his dedication and keen leadership are woven into the Voyager mission,” said Linda Spilker, who joined the mission in 1977 and succeeded him as project scientist.

The Voyager mission was Stone’s crowning achievement, but hardly his only one.

He was a principal investigator on nine NASA missions and a co-investigator on five others, including several satellites designed to study cosmic rays, the solar wind and the Earth’s magnetic field.

He became director of the Jet Propulsion Laboratory in La Cañada Flintridge in 1991, a role he held for a decade.

It was an era of cost-cutting at NASA, but Stone still managed to launch Galileo’s five-year mission to Jupiter and send the Cassini spacecraft to Saturn. He was also at the agency’s helm when Mars Pathfinder delivered the Sojourner rover to the Red Planet. It marked the first time that humans had put a robotic rover on the surface of another planet.


Throughout his tenure at JPL, Stone continued to work and teach at Caltech, even teaching freshman physics during some of Voyager’s long cruise times between planets.

He also served as chairman of the board of the California Assn. for Research in Astronomy, which is responsible for building and operating the W.M. Keck Observatory and its two 10-meter telescopes on Mauna Kea, Hawaii.

Edward Carroll Stone Jr. was born in Iowa on Jan. 23, 1936, and grew up in Burlington, where his father ran a small construction business and his mother kept the company books.

The eldest of two brothers, Stone was attracted to science from a young age. Under his father’s watchful eye, he learned how to take apart and reassemble all varieties of technology, from radios to cars.

“I was always interested in learning about why something is this way and not that way,” Stone told an interviewer in 2018. “I wanted to understand and measure and observe.”


After studying physics at Burlington Junior College, he received his master’s and doctorate at the University of Chicago. Shortly after he began his graduate studies, news broke in 1957 that the former Soviet Union had launched Sputnik, the world’s first artificial satellite.

“Just like that, because of the Cold War and our need to match Sputnik, a whole new realm absolutely opened up,” he said.

Stone built a device for measuring the intensity of solar energetic particles above the atmosphere that hitched a ride to space aboard an Air Force satellite in 1961. Unfortunately the spacecraft’s transmitter didn’t work, so only a very limited quantity of data was returned to Earth. However, it was still enough to indicate that the intensity of the particles was lower than expected.

Despite the transmitter glitch, Stone said the project was thrilling. “We were taking the first steps in a whole new area of research and exploration,” he said. “We were right at the beginning.”

He joined the faculty at Caltech in 1964 and created more space experiments, this time for NASA.


Stone’s particular area of interest was cosmic rays — high-speed atomic nuclei that can originate from explosive events on the sun or from violent events beyond the solar system.

One of his cosmic-ray experiments was included among the 11 major Voyager experiments.

Ed Stone gestures in front of a reddish background

Ed Stone in 2011, about a year before Voyager 1 entered interstellar space.

(Al Seib / Los Angeles Times)

Colleagues praised Stone for his leadership of the Voyager science team.


“He was a great hero, a giant among men,” said Porco, adding that Stone was known to treat everyone — from top scientists to graduate students — with respect.

Voyager team scientist Thomas Donahue put it this way: “Over the years, Ed Stone has proved to be remarkably adept at keeping a bunch of prima donnas on track.”

Stone was elected to the National Academy of Sciences in 1984 and received the National Medal of Science from President George H.W. Bush in 1991 in recognition of his leadership of the Voyager mission. He won the Shaw Prize in Astronomy in 2019, an honor that comes with a $1.2-million award. In 2012 his hometown of Burlington, Iowa, named its new middle school after him.

“This is truly an honor because it comes from the community where my exploration journey began,” Stone told a local newspaper.

Decades after Voyager’s launch he was asked to select his favorite moment from the mission. He chose the discovery of volcanoes on Jupiter’s moon Io.


“Finding a moon that’s 100 times more active volcanically than the entire Earth, it’s really quite striking,” he said. “And this was typical of what Voyager was going to do on the rest of its journey through the outer solar system.

“Time after time, we found that nature was much more inventive than our models,” he said.

His wife, Alice, whom he met on a blind date at the University of Chicago and married in 1962, died in December. The couple are survived by their two daughters, Susan and Janet Stone, and two grandsons.

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Do you get mysterious seasonal headaches? Blame weather whiplash



Do you get mysterious seasonal headaches? Blame weather whiplash

Alanna Santini’s friends call her the “human weather vane.” On cloudy days, the 42-year-old advertising executive from Silver Lake invariably comes down with a bad headache. It’s an experience she grew accustomed to in her home state of New York and something she was happy to escape when she moved west five years ago. But this year, as an unusually dark and stormy Los Angeles winter segued into a rainy, overcast spring, her weather-induced headaches returned with a vengeance — adding a whole new dimension to the term June gloom.

“I’ve been waking up with a headache for the past three months because it has either been raining or on the cusp of raining,” Santini said.

Seasonal headaches are a common if somewhat mysterious phenomenon (it’s important to note that migraines are a type of headache but that all headaches are not migraines). Many people who get either type of headache note that they can occur during sudden shifts in barometric pressure when the weather changes.

Such complaints have become so frequent that scientists and healthcare providers have sought to investigate and explain the correlation. So exactly how do the pervasive clouds and rain contribute to headaches and migraines?


One possible cause could be our sinuses, says Dr. David Gudis, chief of the division of rhinology and anterior skull base surgery at New York-Presbyterian/Columbia University Irving Medical Center. Barometric pressure sinusitis, otherwise known as barosinusitis, is an established medical condition in which people feel intense sinus headaches and inflammation. Gudis describes the sinuses as “compartments of little air-filled cavities, like a honeycomb,” or “an office with lots of cubicles in which each space is an air-filled compartment lined by a mucus membrane, surrounded by bony partitions.”

When sinuses are functioning normally, he says, air moves freely so that the air pressure in the nose and sinuses is the same as in one’s surrounding atmosphere. But when sinuses become blocked, usually due to inflammation, the air pressure inside your sinuses is uneven to that of your surroundings, causing pain or pressure from fluid that can’t drain or air that can’t move around freely.

Barosinusitis is fairly common on flights or when scuba-diving because the atmospheric pressure around us can’t always equalize with the air pressure inside our sinuses. (It also explains why we often feel like our ears need to pop on airplanes). Gudis likens it to the way a half-empty plastic water bottle changes shape on a flight.

“If you drink from a plastic water bottle while you’re on a flight and screw the cap on, when you land it looks like someone squeezed the bottle,” Gudis said. “According to Boyle’s law, if the temperature doesn’t change, pressure and volume are inversely correlated, which means that pressure changes in the environment can cause expansion or contraction of air-space cavities in the body.”

While these concepts may sound like long-forgotten high school physics lessons, they explain why so many of us feel uncomfortable when air pressure changes. While June gloom and other weather patterns occur much more slowly than the sudden rise and fall of air pressure on a flight, you can still feel the same kind of discomfort during correlating barometric shifts, resulting in sinus or ear pain.


For years, experts have been looking into how weather patterns can trigger headaches. Gudis cites a weather phenomenon in the Pacific Northwest known as Chinook winds, strong winds that develop from late fall to early spring. When a straight-line jet stream blows in from the Pacific Ocean.

In 2000, a study was published in Neurology that found these winds could trigger migraines. Other studies have established a link between Vitamin D (which we get naturally from sunlight) deficiency and increased tension headaches and migraines.

Dr. Diana Shadbehr, head of the Headache Clinic at Cedars-Sinai Medical Center in Los Angeles, agrees that barometric pressure can affect sinuses but says researchers haven’t yet been able to prove that weather changes are the sole cause of seasonal headaches and migraines.

“While many patients report worsening of headaches with weather changes, and there was even a research study in Japan that showed a correlation between barometric pressure changes and more headaches, it is difficult to account for all other variables that can trigger a headache such as different foods, stress and hormonal fluctuations,” she wrote via email.

When it comes to weather-induced headaches, everyone’s triggers are different; for some, Shadbehr suggests sunny days may be a trigger.


“Sunlight contains blue wavelengths of light that can trigger a migraine attack,” she said. “Photophobia can occur both in the setting of natural light and synthetic light. Additionally, sunlight exposure can cause dehydration which can also trigger a headache. Light can activate brain cells in areas of the brain that are involved in headaches.”

Whether or not your headaches are tied to the weather, there are ways to seek relief. If you don’t have any contraindications, a dose of acetaminophen or ibuprofen could do the trick. If you feel the headache might stem from your sinuses and it’s OK with your doctor, Gudis says over-the-counter decongestants such as pseudoephedrine, phenylephrine or oxymetazoline can help, as can nasal spray solutions such as fluticasone (steroid-based) or azelastine (an antihistamine). Always consult your doctor first before trying a new medicine. There’s even an app, WeatherX, designed to tip off those who suffer from barometric pressure headaches when a shift is happening.

Santini says she’s sick and tired of feeling sick and tired. Though none of us can control how our heads might respond to the pervasive pall of June gloom, we can stock up on cold and allergy meds and patiently wait for our spring suffering to come to its natural end. Santini, especially, can’t wait. Until then, she says: “Have pain pills, will travel.”

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California plans to enlist AI to translate healthcare information



California plans to enlist AI to translate healthcare information

Tener gripe, tener gripa, engriparse, agriparse, estar agripado, estar griposo, agarrar la gripe, coger la influenza. In Spanish, there are at least a dozen ways to say someone has the flu — depending on the country.

Translating “cardiac arrest” into Spanish is also tricky because “arresto” means getting detained by the police. Likewise, “intoxicado” means you have food poisoning, not that you’re drunk.

The examples of how translation could go awry in any language are endless: Words take on new meanings, idioms come and go, and communities adopt slang and dialects for everyday life.

Human translators work hard to keep up with the changes, but California plans to soon entrust that responsibility to technology.

State health policy officials want to harness emerging artificial intelligence technology to translate a broad swath of documents and websites related to “health and social services information, programs, benefits and services,” according to state records. Sami Gallegos, a spokesperson for California’s Health and Human Services Agency, declined to elaborate on which documents and languages would be involved, saying that information is confidential.


The agency is seeking bids for the ambitious initiative, though its timing and cost is not yet clear. Human editors supervising the project will oversee and edit the translations, Gallegos said.

Agency officials said they hope to save money and make critical healthcare forms, applications, websites, and other information available to more people in what they call the nation’s most linguistically diverse state.

The project will start by translating written material. Agency Secretary Mark Ghaly said the technology, if successful, may be applied more broadly.

“How can we potentially not just transform all of our documents, but our websites, our ability to interact, even some of our call center inputs, around AI?” Ghaly asked during an April briefing on AI in healthcare in Sacramento.

But some translators and scholars fear the technology lacks the nuance of human interaction and isn’t ready for the challenge. Turning this sensitive work over to machines could create errors in wording and understanding, they say — ultimately making information less accurate and less accessible to patients.


“AI cannot replace human compassion, empathy, and transparency, meaningful gestures and tones,” said Rithy Lim, a Fresno-based medical and legal interpreter for 30 years who specializes in Cambodian and Khmer languages.

Artificial intelligence is the science of designing computers that emulate human thinking. A type of artificial intelligence known as generative AI, or GenAI, in which computers are trained using massive amounts of data to “learn” the meaning of things and respond to prompts, is driving a wave of investment, led by such companies as Open AI and Google.

AI is quickly being integrated into healthcare, including programs that diagnose diabetic retinopathy, analyze mammograms and connect patients with nurses remotely. Promotors of the technology often make the grandiose claim that soon everyone will have their own “AI doctor.”

AI also has been a game changer in translation. ChatGPT, Google’s Neural Machine Translation and Open Source are not only faster than older technologies such as Google Translate, but they can process huge volumes of content and draw upon a vast database of words to nearly mimic human translation.

Whereas a professional human translator might need three hours to translate a 1,600-word document, AI can do it in a minute.


Arjun “Raj” Manrai, an assistant professor of biomedical informatics at Harvard Medical School and the deputy editor of New England Journal of Medicine AI, said the use of AI technology represents a natural progression in medical translation, given that patients already use Google Translate and AI platforms to translate for themselves and their loved ones.

“Patients are not waiting,” he said.

He said generative AI could be particularly useful in this context.

These translations “can deliver real value to patients by simplifying complex medical information and making it more accessible,” he said.

In its bidding documents, the state says the goal of the project is to increase “speed, efficiency, and consistency of translations, and generate improvements in language access” in a state where 1 in 3 people speak a language other than English, and more than 200 languages are spoken.


In May 2023, the state Health and Human Services Agency adopted a “language access policy” that requires its departments to translate all “vital” documents into at least the top five languages spoken by Californians with limited English proficiency. At the time, those languages were Spanish, Chinese, Tagalog, Vietnamese, and Korean.

Examples of vital documents include application forms for state programs, notices about eligibility for benefits, and public website content.

Currently, human translators produce these translations. With AI, more documents could be translated into more languages.

A survey conducted by the California Health Care Foundation late last year found that 30% of Spanish speakers have difficulty explaining their health issues and concerns to a doctor, compared with 16% of English speakers.

Health equity advocates say AI will help close that gap.


“This technology is a very powerful tool in the area of language access,” said Sandra R. Hernández, president and CEO of the foundation. “In good hands, it has many opportunities to expand the translation capability to address inequities.”

But Hernández cautioned that AI translations must have human oversight to truly capture meaning.

“The human interface is very important to make sure you get the accuracy and the cultural nuances reflected,” she said.

Lim recalled an instance in which a patient’s daughter read preoperative instructions to her mother the night before surgery. Instead of translating the instructions as “you cannot eat” after a certain hour, she told her mom, “You should not eat.”

The mother ate breakfast, and the surgery had to be rescheduled.


“Even a few words that change meaning could have a drastic impact on the way people consume the information,” said Sejin Paik, a doctoral candidate in digital journalism, human-computer interaction and emerging media at Boston University.

Paik, who grew up speaking Korean, also pointed out that AI models are often trained from a Western point of view. The data that drive the translations filters languages through an English perspective, “which could result in misinterpretations of the other language,” she said. Amid this fast-changing landscape, “we need more diverse voices involved, more people thinking about the ethical concepts, how we best forecast the impact of this technology.”

Manrai pointed to other flaws in this nascent technology that must be addressed. For instance, AI sometimes invents sentences or phrases that are not in the original text, potentially creating false information — a phenomenon AI scientists call “hallucination” or “confabulation.”

Ching Wong, executive director of the Vietnamese Community Health Promotion Project at UC San Francisco, has been translating health content from English into Vietnamese and Chinese for 30 years.

He provided examples of nuances in language that might confuse AI translation programs. Breast cancer, for instance, is called “chest cancer” in Chinese, he said.


And “you” has different meanings in Vietnamese, depending on a person’s ranking in the family and community. If a doctor uses “you” incorrectly with a patient, it could be offensive, Wong said.

But Ghaly emphasized that the opportunities outweigh the drawbacks. He said the state should “cultivate innovation” to help vulnerable populations gain greater access to care and resources.

And he was clear: “We will not replace humans.”

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A tiny fern with a big secret just got into the Guinness Book of World Records



A tiny fern with a big secret just got into the Guinness Book of World Records

Tmesipteris oblanceolata is an obscure species of fork fern found in New Caledonia, a French territory in the South Pacific. Just 4 to 6 inches tall, the humble plant is, in one particular way, the most remarkable living thing in the world.

“You would walk over it. You might even tread on it without knowing it,” said Ilia Leitch, a plant evolutionary biologist and senior research leader at the U.K.’s Royal Botanic Gardens, Kew. “But it houses within it this great secret.”

Recently, T. oblanceolata entered the Guinness Book of World Records after a team of scientists determined that the wispy fern has the biggest known genome of any living organism. Crammed into the nucleus of every one of its cells are 160.45 billion base pairs — 160.45 billion rungs on the twirling double-helix ladder that is the plant’s DNA.

T. oblanceolata has more genes than the mighty California redwood (Sequoia sempervirens) or the massive blue whale (Balaenoptera musculus). It has 50 times more DNA than Homo sapiens, the species that figured out what DNA is in the first place. The findings were published in the journal iScience.

“We were absolutely astonished when we found out how big this genome was,” said botanist Jaume Pellicer of Institut Botànic de Barcelona in Spain, a co-author of the study along with Leitch. “We already knew about the existence of giant genomes in the genus but did not anticipate that the one in Tmesipteris oblanceolata was going to beat any previous records.”


A genome contains all the information cells need to direct the growth and development of the organism. But life doesn’t offer up instructions in the tidy, more-steps-equals-more-complexity way of Ikea or Lego assembly manuals — hence petite ferns with jumbo-sized genetic codes.

A fern with tiny yellow seeds
A view of fern fronds

You might step on T. oblanceolata “without knowing it,” a plant evolutionary biologist said. (Photographs by Pol Fernandez and Oriane Hidalgo)

Measuring genome size is “not a way to measure genome complexity or coding capacity,” said Elliot Meyerowitz, a Caltech biologist who was not involved in the research.

Only a minuscule sliver of the genetic material that most plant and animal cells lug around actually contains direct instructions for how to make the building blocks that make up living things. Less than 2% of the human genome actually codes for proteins. For the fork fern, the research team estimates that less than 1% of its genome does.


The rest is known as noncoding DNA. Understanding what that noncoding genetic material does and why cells haul it around are among the biggest questions in evolutionary biology.

Half a century ago, scientists dismissed this noncoding stuff as “junk DNA,” a term now considered “a reflection of our own ignorance,” Leitch said.

It’s not that it all does nothing, she said. We just don’t yet understand everything that it does.

T. oblanceolata ferns grow amid tangled branches and fallen leaves.

T. oblanceolata ferns grow amid tangled branches and fallen leaves.

(Jaume Pellicer)


In recent years, researchers have found that manipulating or deleting some of these noncoding sequences affect gene expression. This suggests that at least some of this material plays a role in the processes that “switch” genes on and off, “like the conductor of an orchestra, saying who comes in here and who should be quiet here,” Leitch said.

This intricate choreography of gene expression is how we get the incredible diversity within our own species and across the kingdoms of living things.

“Understanding how these genomes function and are structured represents the ultimate milestone in this field of research,” Pellicer wrote in an email. “But for now, it is like trying to read a book of instructions without even knowing where page one is!”

T. oblanceolata displaces the previous genome record holder, a modestly sized flowering plant called Paris japonica that has 149 billion base pairs. While there may be something else out there packing a bigger genetic punch, botanists believe these plants are at the upper end of how much DNA a living thing can have.

A man in a jacket next to a tree, surrounded by ferns and other foliage

A researcher looks for fork ferns in New Caledonia.

(Oriane Hidalgo)


“If it’s not the biggest, it’s jolly well close to it,” Leitch said of the fork fern’s genome. “There are so many consequences associated with having so much DNA that I think we’re at the limits of what biology can cope with.”

An organism has to divide its cells in order to grow, and before it can do that it has to make a copy of all the DNA in its cells. Copying a colossal genome is a big investment of time, energy and nutrients, Leitch pointed out. For plants, bigger genomes are associated with slower growth and less efficient photosynthesis.

As a result, organisms with massive genomes tend to be found in stable environments without much competition, Leitch said. That’s true of T. oblanceolata, slow-growing Paris japonica and the marbled lungfish, holder of the animal kingdom’s largest genome (nearly 130 billion base pairs).

Unfortunately for T. oblanceolata, stable conditions are increasingly hard to come by in a rapidly changing climate.


“As long as they’re stable, as long as things don’t change, selection won’t weed them out, so to speak,” Leitch said. “I would predict that if the environment changed, they would not be in a good position.”

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