Edward Stone: 50 Years at NASA ends, but his brainchild Voyager’s Project goes on

Stone’s remarkable tenure on NASA’s longest-operating mission spans decades of historic discoveries and firsts.

Edward Stone has retired as the project scientist for NASA’s Voyager mission a half-century after taking on the role. Stone accepted scientific leadership of the historic mission in 1972, five years before the launch of its two spacecraft, Voyager 1 and Voyager 2. Under his guidance, the Voyagers explored the four giant planets and became the first human-made objects to reach interstellar space, the region between the stars containing material generated by the death of nearby stars.

Until now, Stone was the only person to have served as project scientist for Voyager, maintaining his position even while serving as director of NASA’s Jet Propulsion Laboratory in Southern California from 1991 to 2001. JPL manages the Voyager mission for NASA. Stone retired from JPL in 2001 but continued to serve as the mission’s project scientist.

“It has been an honor and a joy to serve as the Voyager project scientist for 50 years,” Stone said. “The spacecraft have succeeded beyond expectation, and I have cherished the opportunity to work with so many talented and dedicated people on this mission. It has been a remarkable journey, and I’m thankful to everyone around the world who has followed Voyager and joined us on this adventure.”

Edward Stone

Edward Stone, second from left, and other members of the Voyager team pose with a model of the spacecraft in 1977, the year the twin probes launched. Credit: NASA/JPL-Caltech

Linda Spilker will succeed Stone as Voyager’s project scientist as the twin probes continue to explore interstellar space. Spilker was a member of the Voyager science team during the mission’s flybys of Jupiter, Saturn, Uranus, and Neptune. She later became project scientist for NASA’s now-retired Cassini mission to Saturn, and rejoined Voyager as deputy project scientist in 2021.

Jamie Rankin, a research scientist at Princeton University and a member of the Voyager science steering group, has been appointed deputy project scientist for the mission. Rankin received her Ph.D. in 2018 from Caltech, where Stone served as her advisor. Her research combines data from Voyager and other missions in NASA’s heliophysics fleet.

The twin Voyager spacecraft launched in 1977, on a mission to explore Jupiter and Saturn, ultimately revealing never-before-seen features of those planets and their moons. Voyager 1 continued its journey out of the solar system, while Voyager 2 continued on to Uranus and Neptune – and remains the only spacecraft to have visited the ice giants.

Edward Stone

Edward Stone, left, talks to reporters at a news conference to announce findings from Voyager 2’s flyby of Uranus in 1986. Credit: NASA/JPL-Caltech

Following this “grand tour” of the outer planets, the Voyager Interstellar Mission began. The goal was to exit the heliosphere – a protective bubble created by the Sun’s magnetic field and outward flow of solar wind (charged particles from the Sun). Voyager 1 crossed the boundary of the heliosphere and entered interstellar space in 2012, followed by Voyager 2 (traveling slower and in a different direction) in 2018. Today, as part of NASA’s longest-running mission, both spacecraft continue to illuminate the interplay between our Sun, and the particles and magnetic fields in interstellar space.

“Ed likes to say that Voyager is a mission of discovery, and it certainly is,” said Suzanne Dodd, Voyager project manager. “From the flybys of the outer planets in the 1970s and ’80s, to the heliopause crossing and current travels through interstellar space, Voyager never ceases to surprise and amaze us. All those milestones and successes are due to Ed’s exceptional scientific leadership and his keen ability to share his excitement about these discoveries to the world.”

Among the many honors bestowed on him, Stone has been a member of the National Academy of Sciences since 1984. He was awarded the National Medal of Science from President George H.W. Bush in 1991. When Stone was interviewed on the late-night TV show “The Colbert Report” in 2013, NASA arranged for host Stephen Colbert to present him with the NASA Distinguished Public Service Medal, the agency’s highest honor for a nongovernment individual. In 2019, he received the Shaw Prize in Astronomy from the Shaw Foundation in Hong Kong for his work on the Voyager mission.

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NASA: Are you in an area of Lucy then take a photograph, post it to social media

On Oct. 16, at 7:04 a.m. EDT, NASA’s Lucy spacecraft, the first mission to the Jupiter Trojan asteroids, will skim the Earth’s atmosphere, passing a mere 220 miles (350 kilometers) above the surface. By sling-shotting past Earth on the first anniversary of its launch, Lucy will gain some of the orbital energy it needs to travel to this never-before-visited population of asteroids.

The Trojan asteroids are trapped in orbits around the Sun at the same distance as Jupiter, either far ahead of or behind the giant planet. Lucy is currently one year into a twelve-year voyage. This gravity assist will place Lucy on a new trajectory for a two-year orbit, at which time it will return to Earth for a second gravity assist. This second assist will give Lucy the energy it needs to cross the main asteroid belt, where it will observe asteroid Donaldjohanson, and then travel into the leading Trojan asteroid swarm. There, Lucy will fly past six Trojan asteroids: Eurybates and its satellite Queta, Polymele and its yet unnamed satellite, Leucus, and Orus. Lucy will then return to Earth for a third gravity assist in 2030 to re-target the spacecraft for a rendezvous with the Patroclus-Menoetius binary asteroid pair in the trailing Trojan asteroid swarm.

This illustration shows the Lucy spacecraft passing one of the Trojan Asteroids near Jupiter./CREDIT:Southwest Research Institute

For this first gravity assist, Lucy will appear to approach Earth from the direction of the Sun. While this means that observers on Earth will not be able to see Lucy in the days before the event, Lucy will be able to take images of the nearly full Earth and Moon. Mission scientists will use these images to calibrate the instruments.

Lucy’s trajectory will bring the spacecraft very close to Earth, lower even than the International Space Station, which means that Lucy will pass through a region full of earth-orbiting satellites and debris. To ensure the safety of the spacecraft, NASA developed procedures to anticipate any potential hazard and, if needed, to execute a small maneuver to avoid a collision.

“The Lucy team has prepared two different maneuvers,” says Coralie Adam, Lucy deputy navigation team chief from KinetX Aerospace in Simi Valley, California. “If the team detects that Lucy is at risk of colliding with a satellite or piece of debris, then–12 hours before the closest approach to Earth –the spacecraft will execute one of these, altering the time of closest approach by either two or four seconds. This is a small correction, but it is enough to avoid a potentially catastrophic collision.”

NASA/Photo: Nasa.gov

Lucy will be passing the Earth at such a low altitude that the team had to include the effect of atmospheric drag when designing this flyby. Lucy’s large solar arrays increase this effect.

“In the original plan, Lucy was actually going to pass about 30 miles closer to the Earth,” says Rich Burns, Lucy project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “However, when it became clear that we might have to execute this flyby with one of the solar arrays unlatched, we chose to use a bit of our fuel reserves so that the spacecraft passes the Earth at a slightly higher altitude, reducing the disturbance from the atmospheric drag on the spacecraft’s solar arrays.”

At around 6:55 a.m. EDT, Lucy will first be visible to observers on the ground in Western Australia (6:55 p.m. for those observers). Lucy will quickly pass overhead, clearly visible to the naked eye for a few minutes before disappearing at 7:02 a.m. EDT as the spacecraft passes into the Earth’s shadow. Lucy will continue over the Pacific Ocean in darkness and emerge from the Earth’s shadow at 7:26 a.m. EDT. If the clouds cooperate, sky watchers in the western United States should be able to get a view of Lucy with the aid of binoculars.

“The last time we saw the spacecraft, it was being enclosed in the payload fairing in Florida,” said Hal Levison, Lucy principal investigator at the Southwest Research Institute (SwRI) Boulder, Colorado office. “It is exciting that we will be able to stand here in Colorado and see the spacecraft again. And this time Lucy will be in the sky.”

Lucy will then rapidly recede from the Earth’s vicinity, passing by the Moon and taking a few more calibration images before continuing out into interplanetary space.

“I’m especially excited by the final few images that Lucy will take of the Moon,” said John Spencer, acting deputy project scientist at SwRI. “Counting craters to understand the collisional history of the Trojan asteroids is key to the science that Lucy will carry out, and this will be the first opportunity to calibrate Lucy’s ability to detect craters by comparing it to previous observations of the Moon by other space missions.”

The public is invited to join the #WaveToLucy social media campaign by posting images of themselves waving towards the spacecraft and tagging the @NASASolarSystem account. Additionally, if you are in an area where Lucy will be visible, take a photograph of Lucy and post it to social media with the #SpotTheSpacecraft hashtag.

Instructions for observing Lucy from your location are available here.

 

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Are we alone in the universe? JPL’s OWLS, other tools to help search for life in deep space

A team at the Lab has invented new technologies that could be used by future missions to analyze liquid samples from watery worlds and look for signs of alien life.

Are we alone in the universe? An answer to that age-old question has seemed tantalizingly within reach since the discovery of ice-encrusted moons in our solar system with potentially habitable subsurface oceans. But looking for evidence of life in a frigid sea hundreds of millions of miles away poses tremendous challenges. The science equipment used must be exquisitely complex yet capable of withstanding intense radiation and cryogenic temperatures. What’s more, the instruments must be able to take diverse, independent, complementary measurements that together could produce scientifically defensible proof of life.

To address some of the difficulties that future life-detection missions might encounter, a team at NASA’s Jet Propulsion Laboratory in Southern California has developed OWLS, a powerful suite of science instruments unlike any other. Short for Oceans Worlds Life Surveyor, OWLS is designed to ingest and analyze liquid samples. It features eight instruments – all automated – that, in a lab on Earth, would require the work of several dozen people.

JPL’s OWLS combines powerful chemical-analysis instruments that look for the building blocks of life with microscopes that search for cells. This version of OWLS would be miniaturized and customized for use on future missions. Credit: NASA/JPL-Caltech

One vision for OWLS is to use it to analyze frozen water from a vapor plume erupting from Saturn’s moon Enceladus. “How do you take a sprinkling of ice a billion miles from Earth and determine – in the one chance you’ve got, while everyone on Earth is waiting with bated breath – whether there’s evidence of life?” said Peter Willis, the project’s co-principal investigator and science lead. “We wanted to create the most powerful instrument system you could design for that situation to look for both chemical and biological signs of life.”

OWLS has been funded by JPL Next, a technology accelerator program run by the Lab’s Office of Space Technology. In June, after a half-decade of work, the project team tested its equipment – currently the size of a few filing cabinets – on the salty waters of Mono Lake in California’s Eastern Sierra. OWLS found chemical and cellular evidence of life, using its built-in software to identify that evidence without human intervention.

“We have demonstrated the first generation of the OWLS suite,” Willis said. “The next step is to customize and miniaturize it for specific mission scenarios.”

Challenges, Solutions

A key difficulty the OWLS team faced was how to process liquid samples in space. On Earth, scientists can rely on gravity, a reasonable lab temperature, and air pressure to keep samples in place, but those conditions don’t exist on a spacecraft hurtling through the solar system or on the surface of a frozen moon. So the team designed two instruments that can extract a liquid sample and process it in the conditions of space.

Since it’s not clear what form life might take on an ocean world, OWLS also needed to include the broadest possible array of instruments, capable of measuring a size range from single molecules to microorganisms. To that end, the project joined two subsystems: one that employs a variety of chemical analysis techniques using multiple instruments, and one with several microscopes to examine visual clues.

Water ice and vapor are seen spraying from Saturn’s frozen moon Enceladus, which hosts a hidden subsurface ocean, in this image captured by NASA’s Cassini mission during a 2010 flyby. OWLS is designed to ingest and analyze liquid samples from such plumes. Credit:NASA/JPL/Space Science Institute 

Full Image Details

OWLS’ microscope system would be the first in space capable of imaging cells. Developed in conjunction with scientists at Portland State University in Oregon, it combines a digital holographic microscope, which can identify cells and motion throughout the volume of a sample, with two fluorescent imagers, which use dyes to observe chemical content and cellular structures. Together, they provide overlapping views at a resolution of less than a single micron, or about 0.00004 inches.

Dubbed Extant Life Volumetric Imaging System (ELVIS), the microscope subsystem has no moving parts – a rarity. And it uses machine-learning algorithms to both home in on lifelike movement and detect objects lit up by fluorescent molecules, whether naturally occurring in living organisms or as added dyes bound to parts of cells.

“It’s like looking for a needle in a haystack without having to pick up and examine every single piece of hay,” said co-principal investigator Chris Lindensmith, who leads the microscope team. “We’re basically grabbing big armfuls of hay and saying, ‘Oh, there’s needles here, here, and here.’”

To examine much tinier forms of evidence, OWLS uses its Organic Capillary Electrophoresis Analysis System (OCEANS), which essentially pressure-cooks liquid samples and feeds them to instruments that search for the chemical building blocks of life: all varieties of amino acids, as well as fatty acids and organic compounds. The system is so sensitive, it can even detect unknown forms of carbon. Willis, who led development of OCEANS, compares it to a shark that can smell just one molecule of blood in a billion molecules of water – and also tell the blood type. It would be only the second instrument system to perform liquid chemical analysis in space, after the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) instrument on NASA’s Phoenix Mars Lander.

OCEANS uses a technique called capillary electrophoresis – basically, running an electric current through a sample to separate it into its components. The sample is then routed to three types of detectors, including a mass spectrometer, the most powerful tool for identifying organic compounds.

Sending It Home

These subsystems produce massive amounts of data, just an estimated 0.0001% of which could be sent back to faraway Earth because of data transmission rates that are more limited than dial-up internet from the 1980s. So OWLS has been designed with what’s called “onboard science instrument autonomy.” Using algorithms, computers would analyze, summarize, prioritize, and select only the most interesting data to be sent home while also offering a “manifest” of information still on board.

“We’re starting to ask questions now that necessitate more sophisticated instruments,” said Lukas Mandrake, the project’s instrument autonomy system engineer. “Are some of these other planets habitable? Is there defensible scientific evidence for life rather than a hint that it might be there? That requires instruments that take a lot of data, and that’s what OWLS and its science autonomy is set up to accomplish.”

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No Picnic in the Clouds! It’s JPL aerobot

No Picnic in the Clouds! It’s JPL aerobot

JPL’s Venus Aerial Robotic Balloon Prototype Aces Test Flights

A scaled-down version of the aerobot that could one day take to the Venusian skies successfully completed two Nevada test flights, marking a milestone for the project.

The intense pressure, heat, and corrosive gases of Venus’ surface are enough to disable even the most robust spacecraft in a matter of hours. But a few dozen miles overhead, the thick atmosphere is far more hospitable to robotic exploration.

One concept envisions pairing a balloon with a Venus orbiter, the two working in tandem to study Earth’s sister planet. While the orbiter would remain far above the atmosphere, taking science measurements and serving as a communication relay, an aerial robotic balloon, or aerobot, about 40 feet (12 meters) in diameter would travel into it.

To test this concept, a team of scientists and engineers from NASA’s Jet Propulsion Laboratory in Southern California and the Near Space Corporation in Tillamook, Oregon, recently carried out two successful flights of a prototype balloon that’s about a third of that size.

The shimmering silver balloon ascended more than 4,000 feet (1 kilometer) over Nevada’s Black Rock Desert to a region of Earth’s atmosphere that approximates the temperature and density the aerobot would experience about 180,000 feet (55 kilometers) above Venus. Coordinated by Near Space, these tests represent a milestone in proving the concept’s suitability for accessing a region of Venus’ atmosphere too low for orbiters to reach, but where a balloon mission could operate for weeks or even months.

“We’re extremely happy with the performance of the prototype. It was launched, demonstrated controlled-altitude maneuvers, and was recovered in good condition after both flights,” said robotics technologist Jacob Izraelevitz, who leads the balloon development as the JPL principal investigator of the flight tests. “We’ve recorded a mountain of data from these flights and are looking forward to using it to improve our simulation models before exploring our sister planet.”

The only balloon-borne exploration of Venus’ atmosphere to date was a part of the twin Soviet Vega 1 and 2 missions that arrived at the planet in 1985. The two balloons (which were about 11.5 feet, or 3.6 meters, in diameter when filled with helium) lasted a little over 46 hours before their instruments’ batteries ran out. Their short time in the Venusian atmosphere provided a tantalizing hint of the science that could be achieved by a larger, longer-duration balloon platform floating within the planet’s atmosphere.

A prototype aerial robotic balloon, or aerobot, is readied for a sunrise test flight at Black Rock Desert, Nevada, in July 2022, by team members from JPL and Near Space Corporation. The aerobot successfully completed two flights, demonstrating controlled altitude flight. Credit: NASA/JPL-Caltech

‘Roving’ the Skies

The ultimate goal of the aerobot would be to travel on the Venusian winds, floating from east to west, circumnavigating the planet for at least 100 days. The aerobot would serve as a platform for a range of science investigations, from monitoring the atmosphere for acoustic waves generated by venusquakes to analyzing the chemical composition of the clouds. The accompanying orbiter would receive data from the aerobot and relay it to Earth while providing a global view of the planet.

Much like a Mars rover is commanded to drive to an interesting rock or other feature, the aerobot can be directed to raise and lower its altitude – something the Vega balloons couldn’t do – to conduct science between about 171,000 and 203,000 feet (52 and 62 kilometers) within Venus’ atmosphere.

The prototype balloon was fabricated using Near Space’s techniques for performance aerospace inflatables. Designed as a “balloon within a balloon,” it has a rigid inner reservoir filled with helium under high pressure and an encapsulating outer helium balloon that can expand and contract. To increase altitude, helium vents from the inner reservoir into the outer balloon, which expands to give the aerobot additional buoyancy. When it’s time to reduce altitude, helium is pumped back into the reservoir, causing the outer balloon to shrink and decrease the aerobot’s buoyancy.

“The success of these test flights is a huge deal for us: We’ve successfully demonstrated the technology we’ll need for investigating the clouds of Venus,” said Paul Byrne, an associate professor at Washington University in St. Louis and aerobot science collaborator. “These tests form the foundation for how we can achieve long-term robotic exploration high above Venus’ hellish surface.”

The one-third scale prototype aerobot is designed to withstand the corrosive chemicals in Venus’ atmosphere. During the flights, the balloon’s materials were tested for the first time, giving the team confidence that a larger aerobot design could operate in Venus skies. Credit: Near Space Corporation

No Picnic in the Clouds

While this region of Venus’ atmosphere is more forgiving than its lower reaches, long-duration flights in the rocky planet’s clouds, which contain sulfuric acid and other corrosive chemicals, would be no picnic. So the multilayered material developed for the aerobot’s outer balloon includes an acid-proof coating, a metallization layer to reduce solar heating, and a structural inner layer that keeps it strong enough to carry the science instruments below. New techniques have also been developed to ensure a long-duration acid-proof seal with minimal helium leakage from the seams.

“The materials being used for Venus survivability are challenging to fabricate with, and the robustness of handling we’ve demonstrated in the Nevada launch and recovery gives us confidence for balloon’s reliability on Venus,” said co-investigator Tim Lachenmeier, chief executive officer of Near Space.

While the recent Nevada tests were a milestone for a future concept designed with Venus in mind, the researchers say the technology could also be used by high-altitude science balloons that need to control their altitude in Earth’s skies.

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Turning human waste into plastic, nutrients could aid long-distance space travel

Imagine you’re on your way to Mars, and you lose a crucial tool during a spacewalk. Not to worry, you’ll simply re-enter your spacecraft and use some microorganisms to convert your urine and exhaled carbon dioxide (CO2) into chemicals to make a new one. That’s one of the ultimate goals of scientists who are developing ways to make long space trips feasible.

The researchers are presenting their results today at the 254th National Meeting & Exposition of the American Chemical Society (ACS). ACS, the world’s largest scientific society, is holding the meeting here through Thursday. It features nearly 9,400 presentations on a wide range of science topics.

A brand-new video on the research is available at http://bit.ly/acsmars.

Astronauts can’t take a lot of spare parts into space because every extra ounce adds to the cost of fuel needed to escape Earth’s gravity. “If astronauts are going to make journeys that span several years, we’ll need to find a way to reuse and recycle everything they bring with them,” Mark A. Blenner, Ph.D., says. “Atom economy will become really important.”

The solution lies in part with the astronauts themselves, who will constantly generate waste from breathing, eating and using materials. Unlike their friends on Earth, Blenner says, these spacefarers won’t want to throw any waste molecules away. So he and his team are studying how to repurpose these molecules and convert them into products the astronauts need, such as polyesters and nutrients.

Some essential nutrients, such as omega-3 fatty acids, have a shelf life of just a couple of years, says Blenner, who is at Clemson University. They’ll need to be made en route, beginning a few years after launch, or at the destination. “Having a biological system that astronauts can awaken from a dormant state to start producing what they need, when they need it, is the motivation for our project,” he says.

Blenner’s biological system includes a variety of strains of the yeast Yarrowia lipolytica. These organisms require both nitrogen and carbon to grow. Blenner’s team discovered that the yeast can obtain their nitrogen from urea in untreated urine. Meanwhile, the yeast obtain their carbon from CO2, which could come from astronauts’ exhaled breath, or from the Martian atmosphere. But to use CO2, the yeast require a middleman to “fix” the carbon into a form they can ingest. For this purpose, the yeast rely on photosynthetic cyanobacteria or algae provided by the researchers.

One of the yeast strains produces omega-3 fatty acids, which contribute to heart, eye and brain health. Another strain has been engineered to churn out monomers and link them to make polyester polymers. Those polymers could then be used in a 3-D printer to generate new plastic parts. Blenner’s team is continuing to engineer this yeast strain to produce a variety of monomers that can be polymerized into different types of polyesters with a range of properties.

For now, the engineered yeast strains can produce only small amounts of polyesters or nutrients, but the scientists are working on boosting output. They’re also looking into applications here on Earth, in fish farming and human nutrition. For example, fish raised via aquaculture need to be given omega-3 fatty acid supplements, which could be produced by Blenner’s yeast strains.

Although other research groups are also putting yeast to work, they aren’t taking the same approach. For example, a team from DuPont is already using yeast to make omega-3 fatty acids for aquaculture, but its yeast feed on refined sugar instead of waste products, Blenner says. Meanwhile, two other teams are engineering yeast to make polyesters. However, unlike Blenner’s group, they aren’t engineering the organisms to optimize the type of polyester produced, he says.

Whatever their approach, these researchers are all adding to the body of knowledge about Y. lipolytica, which has been studied much less than, say, the yeast used in beer production. “We’re learning that Y. lipolytica is quite a bit different than other yeast in their genetics and biochemical nature,” Blenner says. “Every new organism has some amount of quirkiness that you have to focus on and understand better.”