Kenneth Chang

Launched 42 years ago, when Jimmy Carter was president, the twin spacecraft have persisted far longer than envisioned, as has their ability to send scientific findings home to Earth.

In a series of papers published Monday in Nature Astronomy, scientists report what Voyager 2 observed at the boundary of the solar wind’s bubble and beyond.

“We’re certainly surprised,” Edward C. Stone, the mission’s project scientist, said of the probe’s longevity during a news conference Thursday. “We’re also wonderfully excited by the fact that they do. When the two Voyagers were launched, the Space Age was only 20 years old. It was hard to know at that time that anything could last over 40 years.”

In many ways, the measurements echoed Voyager 1’s: a jump in the density of particles accompanied by a sharp decrease in their speed, a shift in the magnetic fields.

Voyager 2 also noted some differences, which could give clues about the complicated dynamics in that region of the solar system.

The sun spews in all directions a continuous stream of particles called the solar wind traveling at a speed of 1 million mph. The particles are mostly hydrogen, but, heated to some 3 million degrees Fahrenheit, the atoms are ripped apart into protons and electrons.

At a distance of more than 11 billion miles from the sun, the solar wind, thinning out, is increasingly buffeted by the flow of particles in the interstellar wind and a galactic magnetic field generated by the long ago explosions of distant stars. The interstellar wind is much cooler — just tens of thousands of degrees — and denser.

Voyager 2 is heading in a different direction than Voyager 1, which could explain some of the differences. The sun was also more active in 2012, near the maximum phase of its cycle of activity. The sun is now near its lull, known as the solar minimum.

With Voyager 1, the outward velocity of the solar wind dropped to zero long before the boundary; it was pushed sideways. With Voyager 2, the outward velocities fluctuated, sometimes dipping to zero but then rising again.

Curiously, the distances from the sun for the two crossings out of the solar system were similar. Scientists had expected that the bubble would be pushed outward during the solar maximum and collapse inward during the solar minimum.

“A lot of the models leave a lot to be desired,” said Stamatios Krimigis, a scientist at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, and the principal investigator of one of the Voyager instruments.

Voyager 2 also measured what scientists describe as a magnetic barrier, “like the pileup of slowly moving cars on a major highway, a few miles ahead of the scene of an accident,” Leonard F. Burlaga, a scientist working with the spacecraft’s magnetometer, wrote in an email.

When solar wind slows, the density of particles increases, and the magnetic field strengthens.

“Again, it’s like the cars, which turn away from the lanes of the accident and move slowly along the available lanes,” Burlaga said. “The cars are more densely spaced, the drivers are heated, but they eventually move along.”

The missions were originally designed to last four years to fly by Jupiter and Saturn. Voyager 2 also visited Uranus and Neptune. Voyager 2 still has five functioning instruments for measuring the void; Voyager 1 has four.

Both Voyagers are expected to last another five years or so until their batteries die out. Both are powered by electricity generated by the heat of radioactive plutonium. As the plutonium diminishes, the spacecraft receive less and less energy.

Once the Voyagers shut down, there will be no more data from beyond our solar system for years. Only one other spacecraft, the New Horizons probe that flew by Pluto in 2015 and visited another object in the distant Kuiper belt in January this year, is headed that way. But it is moving more slowly, and its plutonium power will run out before it reaches interstellar space.

“Right now, when the Voyagers go offline, that’s kind of it unless we do something else,” said Ralph McNutt, a physicist at the Johns Hopkins Applied Physics Laboratory.

McNutt is leading a study to look at what it might take to build an ultrafast spacecraft that could leave the solar system in a hurry. The development of NASA’s long-delayed giant rocket, the Space Launch System, makes that mission more plausible.

The mission could also perform what is known as an Oberth maneuver, named after Hermann Oberth, a German physicist who came up with the idea in 1927. A probe would first head to Jupiter, using the giant planet’s gravity to accelerate toward the sun. As it then swings around the sun, the spacecraft would fire a rocket engine, accelerating to a speed where it could cover close to a couple of billion miles a year. That would be more than five times the speed of the Voyagers.

That would be tricky to pull off, however. For such a powered flyby to be effective, the probe would have to travel within 1 million miles or so from the sun.

“Well, it’s not as easy as it sounds,” said Krimigis, who is taking part in the study which should be completed in a couple of years. “At that distance, every metal we know melts.”

This article originally appeared in

Voyager 2's Discoveries From Interstellar Space

The Voyager 2 spacecraft burst out of the bubble of gases expanding from the sun and into the wild of the Milky Way a year ago. It was the second spacecraft to cross that boundary and directly observe the interstellar medium. Its faster-moving twin, Voyager 1, made the crossing six years earlier, in August 2012.

That is one of the musings of chemists at New York University who came across an insecticide that had been developed by German scientists during World War II in the course of conducting abstract research on another topic.

It became a historical science mystery.

“Two years ago, we never thought we’d be doing this,” said Michael D. Ward, an NYU chemistry professor.

In postwar Allied intelligence reports examined by Ward and his colleagues, German scientists claimed their insecticide, now called DFDT, was more effective than DDT. Allied officials dismissed those assertions as fanciful, especially given the deplorable behavior of Hoechst, the German chemical manufacturer that developed the insecticide, during the war. The company had forced residents of countries occupied by Germany to work in its factories, and it tested drugs on concentration camp prisoners.

The insecticide was forgotten for decades.

Now, work by Ward and his colleagues, reported this month in an article in the Journal of the American Chemical Society, appears to corroborate the German claims. The forgotten compound killed mosquitoes in as little as one-fourth the time as DDT.

DDT, initially regarded as a magical miracle chemical, was sprayed profusely after World War II until environmental concerns arose in the 1960s. Although many nations banned it in the 1970s, some use still continues. In 2006, the World Health Organization endorsed the use of DDT as part of efforts to control malaria, primarily for the spraying of indoor walls. That involves much smaller amounts than what was used by farmers in the past.

Conceivably the more lethal DFDT could be used in even smaller, possibly safer doses. A new option could allow public health officials to rotate insecticides and thwart the resistance to DDT in many mosquitoes today.

“It’s exciting and desperately needed,” said Duane J. Gubler, an emeritus professor in the emerging infectious diseases program at Duke University and the National University of Singapore Graduate Medical School. He was not involved in the study.

But will anyone today risk the time and money needed to determine whether DFDT could be a safe and effective tool against malaria as well as other mosquito-borne diseases like Zika, dengue and yellow fever?

“Donors, governments, they just don’t want the backlash, even if it’s not wholly justified,” said Bart Kahr, Ward’s colleague at NYU and an author of the paper.

The effectiveness of DDT, an abbreviation for dichloro-diphenyl-trichloroethan, as an insecticide was first discovered in 1939 by Paul Hermann Müller, a Swiss chemist. His company, J.R. Geigy, in Basel, patented the compound.

DDT is what is known as a contact insecticide. “The insects have to walk on the crystals in order to die,” Kahr said.

After DDT is absorbed through an insect’s feet, it binds to nerve cells, causing them to become stuck in the “on” position, firing continuously. The compound does not have that effect in mammals.

The United States and other Allies licensed DDT from Geigy and manufactured as much as they could to control malaria and typhus during World War II. After the war, DDT was widely used by farmers, and over the years, 2 million tons of the insecticide were sprayed.

An aggressive effort by World Health Organization to eradicate malaria in 1955 succeeded in some parts of the world, but many mosquitoes subsequently developed resistance — the survivors were more likely to possess a genetic trait that protected them from the poison, which they passed to their many offspring. The disease roared back.

“We knocked them down, and then after a while they fly away,” Gubler said.

A turning point leading to the decline of DDT was the publication in 1962 of “Silent Spring” by Rachel Carson. The book was a harbinger of the environmental movement, documenting the ecological devastation caused by indiscriminate use of insecticides. DDT molecules endure for decades and accumulate in animals higher up the food chain.

The United States banned DDT in 1972, and many other nations followed.

Kahr and Ward think the outcome might have been different if the substance developed by the Nazi-era scientists had been used instead.

The NYU chemists started the research with no interest in insecticides whatsoever.

They were studying materials that crystallize in a twisted helical pattern. One of the ways to identify such molecules is to scan the internet for images of crystals made by hobbyists. DDT, they found, exhibited the characteristic pinwheel gradients of a helical crystal when illuminated with polarized light.

Jingxiang Yang, a postdoctoral researcher at NYU, started growing DDT crystals and found not only the expected crystals but also more jumbled, chaotic patterns.

“There was some organized and some crazy,” Kahr said. “We didn’t expect the other stuff, and that other stuff turned out to be a different arrangement of molecules in the crystal. That form wasn’t known to science.”

That led to the next set of experiments. “Since we have two forms,” Kahr said, “it was natural to ask, which of these forms was the historical killer of insects?”

It turned out that the chaotic form of DDT is deadlier.

As they were going through early scientific data on DDT, the NYU chemists found mentions of DFDT.

The compound, difluoro-diphenyl-trichloro-ethane, is the same molecule as DDT, except with fluorine atoms replacing two of the chlorines.

The Germans developed DFDT at least in part to avoid paying the licensing fees for DDT to the Swiss. It is also possible that the chemical ingredients for DFDT, although considerably more expensive at the time than those for DDT, may have been more readily available in wartime Germany.

Allied military officials noted the German use of DFDT but concluded that claims of superiority to DDT “are not clearly supported by their meager and inadequate tests against houseflies.”

As DDT use burgeoned, DFDT was forgotten, even after Paul Hermann Müller, who won the Nobel Prize in medicine in 1948 for his work with DDT, praised DFDT, noting that it killed mosquitoes more quickly.

In the NYU experiments, DFDT killed off half of the mosquitoes subjected to it in about half an hour, compared to a couple of hours for DDT.

Kahr wonders: If DFDT had displaced DDT, would the 1955 push have succeeded in bringing malaria under control before resistance set in? “What if this compound wasn’t forgotten,” he said. “What would the world be like? Science doesn’t go as linearly as the general public thinks it does.”

Contemporary experts in insecticide use are skeptical of DFDT’s prospects as a solution to malaria, pointing to similarities in its chemical structures to DDT’s.

“I suspect that the mode of action of DFDT is probably identical to DDT in this respect,” said Jeffrey R. Bloomquist, a professor of insecticide toxicology and resistance at the University of Florida. “So there would be cross resistance to it in the field, even though it has not been in use.”

Helen Jamet, deputy director of vector control for the malaria team at the Bill and Melinda Gates Foundation, also said that a DDT-like insecticide may not be up to the task. “It would not be helpful to put a molecule out there to which there is already widespread resistance in the field,” she said.

Rather, the bigger hope is to find new chemicals that kill mosquitoes through different biological mechanisms. Jamet said that several are in development and could be ready for use in two to three years.

Ward responded that sometimes, as researchers developing drugs have found, the change of a single atom can dramatically change the chemical behavior of a molecule.

The NYU scientists are planning to collaborate with Ke Dong, an entomologist at Michigan State University, to test DFDT on DDT-resistant mosquitoes. “We will see,” she said.

If DFDT can kill those, it potentially could be an important new tool — insecticide resistance can be minimized by periodically switching to a different insecticide. And the amounts needed for battling malaria are small.

“What the environmentalists don’t say and realize is that if it’s used for public health and not agriculture, there’s very little environmental impact,” Gubler said.

But the study’s authors agree that more research would be required to prove that hypothesis.

“We’re not in a position to say this should be used now,” Kahr said. “We don’t know the real environmental impact and the toxicology and effect on ecosystems, and all of that stuff would have to be studied by other scientists that aren’t really us.”

A Nazi Version of DDT Was Forgotten. Could It Help Fight Malaria?

What if, after the Allies won World War II, world health officials had employed a Nazi version of DDT against mosquitoes that transmit malaria? Could that persistent disease, which still infects more than 200 million people a year and kills 400,000 of them, have been wiped off the planet?

The new spacesuits will offer improvements over existing models for the men and women expected to wear them, including greater comfort and movement. And as NASA races to meet the Trump administration’s 2024 target for returning to the moon, the agency needs to make sure that astronauts have the technological capability to safely set foot on the surface, which no human has done since 1972.

One spacesuit, with a bright red, white and blue pattern, is called the exploration extravehicular mobility unit. That is what astronauts will wear as they explore the moon’s surface.

The moon suit, provides additional mobility for an astronaut, making it easier to walk, bend and twist.

Astronauts will be able to reach across the suit and lift their arms above their heads.

The suits are designed to work in temperatures ranging from 250 degrees Fahrenheit down to minus 250 degrees Fahrenheit and potentially even colder places around the lunar south pole, where NASA is aiming to send astronauts.

The other suit, in a bright orange fabric, is to be worn by astronauts during launch and reentry back to Earth while they are sitting inside the Orion crew capsule, the spacecraft for deep-space travel that NASA has been working on for 15 years. The suit provides protection and oxygen to the astronauts in case of an accident that causes the capsule to be become depressurized. It is designed to keep astronauts alive for six days.

NASA’s new suits will be made in a wider range of sizes than had been previously available. In March, a spacewalk that was to be the first conducted by two women, Christina Koch and Anne McClain, had to substitute a male astronaut, Nick Hague, because there were not two spacesuits on the station that fit both women.

When the Trump administration announced its intent to send astronauts back to the moon by 2024, NASA was missing a few crucial pieces for the mission. In addition to updated spacesuits, the agency does not currently have a spacecraft capable of landing on the moon.

NASA officials have insisted the spacesuits would be ready by 2024. That would avert the possibility of American astronauts landing on the moon and just looking out the windows without any garments they could wear to step outside.

NASA's New Spacesuits Unveiled, for Trips to the Moon and Beyond

WASHINGTON — At NASA headquarters Tuesday, officials introduced two prototype spacesuits to be used during upcoming moon missions.

“We’ve been working for a long time to build spacesuits that will do the job on the moon and going on to Mars,” said Amy Ross, a spacesuit engineer at NASA’s Johnson Space Center in Houston.

One spacesuit, with a colorful bright red, white and blue pattern, is called the exploration extravehicular mobility unit. That is what astronauts will wear as they explore the moon’s surface.

The moon suit, demonstrated by Kristine Davis, who works in the agency’s spacesuit engineering efforts, provides additional mobility for an astronaut, making it easier to walk, bend and twist.

Astronauts will be able to reach across the suit and lift their arms above their heads. “Which they can’t do today and couldn’t do during the Apollo program,” Ross said.

“You remember Neil Armstrong and Buzz Aldrin, they bunny hopped on the surface of the moon,” Jim Bridenstine, NASA’s administrator, said. “Well now we’re actually going to be able to walk on the surface of the moon, which is very different than our suits in the past.”

The suits are designed to work in temperatures ranging from 250 degrees Fahrenheit down to minus 250 degrees Fahrenheit and potentially even colder places around the lunar South Pole, where NASA is aiming to send astronauts.

“The primary use in the case of an accidental depressurization,” said Dustin Gohmert, a spacesuit engineer who modeled the Orion suit. “We can take safe haven in this suit. We’ll seek refuge in here.”

Each outfit shared similarities with its utilitarian predecessors worn by earlier astronauts. Spacesuits being designed elsewhere have more futuristic and fashionable appearances.

SpaceX, which has a contract to fly astronauts to the International Space Station in the near future, sent a mannequin wearing its suit to orbit in March. It featured a 3D-printed helmet and a black and white design that seemed to take inspiration from motorcycle racing suits.

Boeing, whose Starliner will also travel to the station, debuted its blue, zippered suit in 2017. It is about 10 pounds lighter than what astronauts wore on the space shuttle.

(Koch and another astronaut, Jessica Meir, are scheduled for the first all-female spacewalk this week.)

NASA had been planning to return to the moon in 2028. By moving up the date four years, the leisurely pace had to be greatly accelerated.

The space agency last month issued a call for commercial companies to propose a lunar lander that could be built that quickly. The deadline for proposals is Nov. 1.

NASA officials have insisted the spacesuits would be ready by 2024. That would avert the comical possibility of American astronauts landing on the moon and just looking out the windows without any garments they could wear to step outside.

One suit, in a bright orange fabric, is to be worn by astronauts during launch and reentry back to Earth while they are sitting inside the Orion crew capsule, the spacecraft for deep-space travel that NASA has been working on for 15 years. The suit provides protection and oxygen to the astronauts in case of an accident that causes the capsule to be become depressurized.

The other spacesuit, with a colorful bright red, white and blue pattern, is called the exploration extravehicular mobility unit. That is what astronauts will wear as they explore the moon’s surface.

The moon suit, demonstrated by Kristine Davis, who works in the agency’s spacesuit engineering efforts, provides additional mobility for an astronaut, making it easier to walk, bend and twist. Jim Bridenstine, NASA’s administrator, highlighted the bunny hopping of earlier American visitors to the moon and said future astronauts would more readily be able to take steps.

“Which future do you want?” he asked near the start of a presentation Saturday night at a launch site near the southern tip of Texas, during which he said the options were being “confined to Earth” or becoming a spacefaring species.

Musk said he hoped the audience agreed that humans should prepare for life elsewhere in the solar system as he delivered a progress report on Starship, a giant rocket that is the centerpiece of his ambitions.

Standing before the prototype and a rocket built earlier in the company’s history, he pledged that Starship would first take off to an altitude of 65,000 feet and then land, “in about one to two months.”

“This is going to sound totally nuts,” he said later, “but I think we want to try to reach orbit in less than 6 months,” adding that this timeline relied on continued improvements in manufacturing the rockets.

What Is Starship?

Starship is the latest name for the upper stage of what Musk had been calling BFR. The “B” stood for Big, the “R” stood for Rocket, and Musk never publicly stated the meaning of “F.”

SpaceX currently flies two rockets: the Falcon 9 and the Falcon Heavy, which is essentially a Falcon 9 with two additional Falcon 9 boosters attached to the side. The present-day Falcons are too small for sending people to Mars.

Musk and SpaceX have long envisioned a much larger rocket. For a while, Musk referred to it as the “Mars Colonial Transporter.” But when he finally revealed a design at the International Astronautical Congress in Guadalajara, Mexico, in 2016, he called it the “Interplanetary Transport System.”

This spaceship was gargantuan, with a diameter of nearly 40 feet, and the capacity to take 100 people to Mars.

A year later in Australia, Musk said the rocket had been scaled down by one-quarter, to a diameter of 30 feet. This was the BFR. The second stage was a sleek-looking spacecraft that would return to Earth in one piece and land vertically.

Last November, SpaceX announced the Starship name; the first stage of BFR is now known as the Super Heavy booster. In recent days, Musk has been posting updates as the prototypes come together.

On Saturday before Musk’s presentation, SpaceX highlighted Starship’s size by displaying it alongside the company’s original Falcon 1 rocket, which first launched to orbit in 2008.

Can This Really Be Done?

Starship with the Super Heavy booster is essentially a rocket as powerful as a Saturn 5, which took NASA’s Apollo astronauts to the moon 50 years ago, but it’s fully reusable. For Apollo, everything but the small capsule on top, where the astronauts sat, was discarded along the way, and even the capsule could be used only once.

Experts say Starship is within the realm of the possible, without requiring impossible physics or unlikely technological leaps. Indeed, Starship employs ideas that were studied decades ago but never built. The biggest innovation is perhaps that SpaceX and Musk have applied the accelerated research-and-development approach of Silicon Valley, building fast and fixing failures fast.

Two competing teams at SpaceX are each building prototypes of Starship. One is in Florida, near Cape Canaveral; the other is at Boca Chica in Texas.

Why Is Starship Shiny and Silver?

While most rockets these days have more utilitarian appearances, SpaceX’s prototype resembles something from a sci-fi movie of the 1950s.

In part, that is because in its rush to get the prototypes to the launch pad, SpaceX has not bothered with such aesthetic niceties as paint. But there also are good engineering reasons for the choice of material.

Musk originally had planned to use high-tech carbon fiber, but switched to stainless steel. Steel is heavier than carbon fiber and aluminum, another common material used for rockets, but it is also cheaper — about 2% of the cost of carbon fiber, Musk said — and has a higher melting temperature that can more easily withstand the heat of re-entry into Earth’s atmosphere.

Didn’t SpaceX Already Fly a Big Rocket?

In August, SpaceX tested a simple prototype that it called Starhopper, with a single engine, which Musk earlier compared to a flying water tower. It lifted to an altitude of 500 feet, flew sideways and then set down at a different spot.

The flight lasted 57 seconds. A shorter July flight went 65 feet in the air.

When Will Starship Take Off?

At Saturday’s presentation, Musk provided updated schedules for the next phase of test launches, which will start with suborbital flights before heading to orbit. SpaceX officials have said that a cargo version of Starship could start launching satellites as early as 2021.

A Japanese billionaire, Yusaku Maezawa, has purchased an around-the-moon trip on a Starship that is to take off in 2023.

Musk, however, has a history of overly optimistic predictions. In Guadalajara in 2016, for example, he said the aim was to send the first cargo flight to Mars in 2022 and the first people there two years later. Those dates are unlikely to be met.

On Friday, NASA Administrator Jim Bridenstine reminded Musk that NASA, SpaceX’s biggest and most important customer, was awaiting the delivery of another big SpaceX project: taking NASA astronauts to the International Space Station in the company’s Crew Dragon capsules.

Neither SpaceX nor Boeing, which also received a contract for providing transportation for NASA astronauts, appears to be on track to launch crews this year. When the contracts were awarded in 2014, NASA hoped that the flights would begin as early as 2017.

On Saturday, Musk responded to Bridenstine’s comments, stating that, “the vast majority,” of SpaceX’s resources were focused on its current rockets and capsules, including the Crew Dragon capsule for NASA.

How Does SpaceX Make Money with Starship?

While experts find Starship to be technologically feasible, they do question how SpaceX can make enough money with it. Without a profitable business, SpaceX could not finance its expensive Mars ambitions, which are unlikely to make money anytime soon.

Musk has talked of the Starship replacing both Falcon 9 and Falcon Heavy. But the rocket is much bigger than needed: Think of taking a semitrailer truck to go grocery shopping.

A cargo Starship could conceivably take up several satellites at once, but satellites typically circle Earth in different orbits, and coordinating launches among different customers is difficult.

SpaceX officials have also talked about how Starship could shuttle people across the world at speeds much faster than airplanes; a flight from New York to Tokyo could take less than an hour. Still, the question remains: How many people are willing to pay at great expense for a faster trip?

How Does Starship Compare to NASA’s Rockets?

NASA is working on its own big rocket, called the Space Launch System, that will initially be able to lift about 70 metric tons; a later, upgraded version is to lift 130 metric tons. (Starship with Super Heavy will lift more than 100 metric tons.)

But while SpaceX’s Starship and Super Heavy take advantage of cutting-edge technologies and are fully reusable, SLS is largely a remix of components from the retired space shuttles.

It is also not reusable; estimates are that it will cost $1 billion per launch, and launch no more than once a year.

NASA also already spent billions on SLS, first announced in 2011, and Orion, the crew-carrying capsule. The first SLS flight has been delayed for years; it is not expected to lift off until 2021. The first moon landing by astronauts is to occur on the third launch of SLS.

Couldn’t NASA Just Buy Rides on Starship?

The delays and cost overruns of SLS frustrate many space aficionados, as well as NASA’s inspector general and the U.S. Government Accountability Office. Some contend NASA could get places quicker and more cheaply if it took better advantage of commercial developments like Starship.

However, to date, Congress, which decides NASA’s budget and priorities, has continued to finance work on SLS and Orion.

Musk Sets Out SpaceX Starship's Ambitious Launch Timeline

BOCA CHICA VILLAGE, Texas — As Elon Musk, the founder and chief executive of SpaceX, says repeatedly, he created a rocket company because he wanted to colonize Mars. His fervent argument is that humanity must spread to a second planet as insurance for long-term survival.

On Saturday, Musk will give a progress report on Starship, a giant rocket that is the centerpiece of those ambitions, at SpaceX’s launch site near the southern tip of Texas.

The update is expected to begin at 8 p.m. Eastern time. You can watch it at SpaceX’s website.

A year later in Australia, Musk said the rocket had been scaled down by one-quarter, to a diameter of 30 feet. This was the BFR. The second stage was sleek-looking spacecraft that would return to Earth in one piece, and land vertically.

Starship with the Super Heavy booster is essentially a rocket as powerful as a Saturn 5, which took NASA’s Apollo astronauts to the moon 50 years ago, but it’s fully reusable. For Apollo, everything but the small capsule on top, where the astronauts sat, was discarded along the way, and even the capsule could only be used once.

While most rockets these days have more utilitarian appearances, SpaceX’s prototype resembles something from an old sci-fi movie of the 1950s.

In part, that is because in its rush to get the prototypes to the launchpad, SpaceX has not bothered with such aesthetic niceties as paint. But there also are good engineering reasons for the choice of material.

Musk originally had planned to use high-tech carbon fiber, but switched to stainless steel. Steel is heavier than carbon fiber and aluminum, another common material used for rockets, but it is also cheaper and has a higher melting temperature that can more easily withstand the heat of re-entry into Earth’s atmosphere.

At Saturday’s presentation, Musk is likely to provide updated schedules for the next phase of test launches, which will start with suborbital flights before heading to orbit. SpaceX officials have said that a cargo version of Starship could start launching satellites as early as 2021.

How Does SpaceX make money with Starship?

Elon Musk to Deliver SpaceX Starship Presentation

The cause was a heart attack, his stepson Sasha Dobrovolsky said.

Feigenbaum’s intense, eclectic curiosity led him to questions far astray from the ones usually asked by theoretical physicists. How does one make the most accurate maps? What makes the moon look larger when it is closer to the horizon? What design of paper money would thwart photocopying?

His friends recalled meals, full of red wine and red meat (no vegetables), at which the conversation — not just about physics but also about literature and classical music — would stretch late into the night.

Feigenbaum’s lifestyle and his Renaissance intellect were a poor fit to the demands of modern publish-or-perish academia. But by following his own path, he uncovered a pattern of chaos that is universal in math and in nature.

At Los Alamos National Laboratory in New Mexico in the mid-1970s, Feigenbaum, using a programmable calculator, found what seemed at first a mathematical curiosity. A simple equation generated a sequence of numbers, which were initially trivial: the same number over and over. But as a parameter in the equation shifted, the output became more varied. First the numbers bounced back and forth between two values, then they cycled among four values, then eight, and so on, with the rate of the change quickening until the patterns lost all hint of repeating cycles.

The dynamics had, in the terminology of physics, passed into the realm of deterministic chaos. That is, each number of the sequence could be computed precisely, but the resulting pattern appeared to be complex and random.

Feigenbaum looked at another simple equation, and it exhibited the same behavior, known as period doubling. More startling, the number that characterized the rate of doubling was the same: As the periods multiplied, each doubling occurred about 4.669 times as quickly as the previous one.

This number is now known as the Feigenbaum constant. Feigenbaum was able to prove why it is a universal mathematical value, much as pi — the ratio of the circumference of a circle to its diameter — is the same for all circles.

“There aren’t too many fundamental constants,” said Kenneth Brecher, an emeritus professor of astronomy at Boston University, who met Feigenbaum when both were graduate students at the Massachusetts Institute of Technology. “And he was the only living person that had one.”

In 1979, a French scientist, Albert J. Libchaber, observed the same cascade of period doublings in the temperature fluctuations in the center of a convecting fluid. Feigenbaum’s theory of the transition from order to chaos now described phenomena in the real world.

“It’s observed in nature and not simply mathematical equations,” said David Campbell, a physics and engineering professor at Boston University and a longtime friend of Feigenbaum’s.

The same ideas have now also been applied to describe the rise and fall of fish populations, the dripping of a leaky faucet and the swings of financial markets.

“We know systems can do this,” Campbell said. “We understand that, and so we know to look for it. When you find, let’s say, period doubling transitions in dung beetle reproduction, it’s not a huge surprise.”

Mitchell Jay Feigenbaum was born in Philadelphia on Dec. 19, 1944, and grew up in Brooklyn, the son of Abraham and Mildred Feigenbaum. His father was a chemist, his mother a schoolteacher. After graduating with a bachelor’s degree in electrical engineering from the City College of New York, he pursued particle physics at the Massachusetts Institute of Technology, completing his doctorate in 1970.

During a postdoctoral fellowship at Cornell, Feigenbaum was already allowing his focus to wander. “He was not very happy with the physics he was doing at that time,” said Predrag Cvitanovic, a theoretical physicist at the Georgia Institute of Technology, who was a graduate student at Cornell at the time.

“The main thing he did is he solved the New York Times crossword puzzle every morning,” Cvitanovic said. “It was just clear that he was very smart. He didn’t produce anything I was aware of.”

A second unproductive postdoctoral fellowship followed, at Virginia Polytechnic Institute and State University in Blacksburg, Virginia. And then a shake-up at Los Alamos rescued Feigenbaum.

Peter A. Carruthers had been installed as director of the laboratory’s theoretical division and wanted to revitalize it. He dismissed some senior scientists and recruited promising younger scientists — including Feigenbaum, even though he did not possess much of a track record.

Feigenbaum moved to Los Alamos in 1974. A year after his arrival, he made his breakthrough on period doubling. Publishing his findings took a few years more.

“The referees rejected it, because he had submitted it to a normal math journal,” Brecher said. “They didn’t know what he was talking about.”

Feigenbaum’s ideas took hold in the 1980s. He moved to Cornell in 1982 as a physics professor and to Rockefeller University in 1986.

In 1984, he won a MacArthur Fellowship (the so-called genius grant of no-strings-attached money), and in 1986 he and Libchaber shared the Wolf Prize in Physics, which is often a precursor to a Nobel. He was a member of the National Academy of Sciences and the American Academy of Arts and Sciences.

Feigenbaum worked in other areas as well — cartography, for example, with the Hammond World Atlas Corp. Projecting cartographic details from a round world onto a flat piece of paper necessarily requires distortion. Feigenbaum figured out what projection would be most accurate for a given region and converted the time-consuming manual mapmaking process into a quick digital one.

He also figured out an efficient method of placing labels on maps. Instead of relying on the whim of the mapmaker, Feigenbaum used physics. He imagined placing electrical charges on the words. Similar charges repel each other, and thus the words would shift to ideal spacing, subject to other mapmaking requirements; the name of a river, for example, needed to be next to the river without obscuring the river.

While serving on a National Research Council committee on the design of next-generation currency design in 1993, Feigenbaum developed a fractal-based geometric pattern that digital copiers could not reproduce without visible flaws.

In 1996, he helped found Numerix, a company that produced software to quickly calculate the risk and pricing of financial derivatives.

“He didn’t publish very much, but he did a lot of work,” said Nigel Goldenfeld, a University of Illinois physicist and another founder of Numerix. “He was motivated by a sense of beauty, and he saw the beauty in a lot of different problems.”

In addition to his stepson Sasha, Feigenbaum is survived by another stepson, Kiril Dobrovolsky; a brother, Edward; and a sister, Glenda Jeunelot. His marriages to Cornelia Dobrovolsky and Gunilla Ohman ended in divorce.

In the past decade, Feigenbaum was fascinated by anamorphic art — images that appear three-dimensional when reflected off a cylindrical mirror.

He wrote a 238-page manuscript, “Reflections on a Tube,” about how what one sees is influenced not only by the physics of optics but also by the peculiarities of the human vision system. Even though the book has been almost finished for a decade, Feigenbaum continued to tinker with it. Friends say they will now finally publish it.

This article originally appeared in <a href="https://www.nytimes.com/2019/07/18/science/mitchell-feigenbaum-dead.html" id="666a2852-dd10-343a-acf0-89e5e6d6dcf8">The New York Times</a>.

Mitchell Feigenbaum, Physicist Who Made Sense of Chaos, Dies at 74

Mitchell J. Feigenbaum, a pioneer in the field of mathematical physics known as chaos, died June 30 in New York. He was 74.

“Let’s pay tribute to this man,” said Schmitt, the only professionally trained scientist among the Apollo astronauts. A ballroom packed with scientists erupted in exuberant applause.

“Neil turned out to be the best field geologist on the moon,” he added. “Until Apollo 17, of course. In 20 minutes or so, he collected a fantastic suite of samples.”

Before Apollo 11, even simple questions about the moon confounded scientists. For instance, how old was it, anyway?

Once they started examining the 50 pounds of rocks and soil brought back by Armstrong and Buzz Aldrin, the answer quickly became clear: very, very old.

Schmitt said that had the Apollo program stopped then, with no additional landings, including his own, those first lunar samples would have been enough to forever reshape knowledge of the solar system.

Armstrong collected two types of rocks: basalts, which are hardened pieces of lava, and breccias, which are fragments of older rocks fused together. The landing site was within a flat lava plain, which was chosen because it appeared to be a safe place to touch down, not because it looked scientifically intriguing.

Nonetheless, the basalts rewrote solar system history. The relative amounts of certain long-lived radioactive elements within the rocks gave a range of ancient ages, unchanged since they cooled and solidified out of lava between 3.6 billion and 3.9 billion years ago. That is far older than almost all of the rocks on Earth, which have been churned, compressed, melted and resolidified over the eons. In fact, the moon rocks were nearly as old as the Earth and the solar system, which formed 4.5 billion years ago.

“Right there, we knew the moon was going to be, at least in part, the record for the early history of the Earth,” Schmitt said. “That was not clearly understood before Apollo 11. But it is clearly understood afterwards and now.”

Another major discovery lay within soil that Armstrong picked up and dropped into the collection box, because it was not packed full. The soil contained bits of a rock known as anorthosite. Just as ice floats on water, anorthosite, made of the mineral plagioclase, floats on magma.

Within half a year after Apollo 11, two teams of scientists, one at the University of Chicago, the other at Harvard, independently used the presence of anorthosite to come up with what was then a radical notion: The moon, the scientists proposed, had at one point melted into a global ocean of magma.

Buoyant anorthosite would then have risen to the surface while heavier materials, like iron, would have sunk to the core. Speculation of a lunar magma ocean, in turn, led to the hypothesis that the moon formed out of the debris from a collision between Earth and a Mars-size body.

“The concept, the phrase magma ocean, didn’t exist until Apollo 11,” Schmitt said in an interview. “That’s the way science moves.”

Rocks from later Apollo missions added evidence to the theory.

Armstrong’s soil also contained hydrogen, helium, nitrogen and carbon, much of which had been deposited by the solar wind, the stream of high-speed particles continually flying outward from the sun. A light version of helium, helium-3, is of particular future interest as fuel for fusion reactors, which could generate bountiful, nearly clean energy by combining atoms.

At the start of a talk at the Lunar and Planetary Science Conference in Houston in March, Harrison Schmitt, one of the two astronauts who walked on the moon during Apollo 17, the last lunar mission, put up a picture of Neil Armstrong.

Kenneth Chang

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