Editor’s Note: This story was updated February 9 to note President Trump’s fiscal year 2019 budget proposal.
A two-year spending package, passed by Congress in the wee hours of February 9 and signed into law by President Trump hours later, could add to the coffers of U.S. science agencies.
The bipartisan deal raises the caps on defense and nondefense discretionary spending by nearly $300 billion overall. Nondefense discretionary spending gets a $63 billion boost in fiscal year 2018, and another $68 billion in FY 2019 (the spending year that starts October 1, 2018). Here’s why that could be good for science: Almost all research agencies, including NASA, EPA, the National Science Foundation and the National Institutes of Health, fall under this nondefense category. (Defense agencies also do a chunk of scientific research.) But there is a big but. It’s still unclear how any funds will be divvied up among individual agencies and programs. (Early word is that NIH is in line for a $2 billion increase over the two years.) Still, the real details of who gets what in the 2018 budget — including what science will get federal funding support — will come as Congress works on an omnibus appropriations bill, expected in late March. Trump’s FY 2019 budget proposal, released February 12, includes a last-minute addendum that would keep science spending roughly at 2017 levels for some major research agencies, including NIH, NSF and the Department of Energy Office of Science. But a number of federal research programs and projects remain in Trump’s cross hairs, including five of NASA’s Earth science missions and various research, including on climate or environmental science, at the EPA, the National Oceanic and Atmospheric Administration and the U.S. Geological Survey. Whether Congress will go along with Trump’s request for the 2019 budget remains to be seen.
Matt Hourihan, director of the R&D Budget and Policy program at the American Association for the Advancement of Science in Washington, D.C., spoke with Science News February 9 about the prospects for funding for science research. His answers were edited for clarity.
SN: What does the spending deal mean for science research and technology funding?
M.H.: Generally, research and development funding tends to track the discretionary budget pretty closely, though individual agencies may fare a little better or worse in any given year. But most likely we’re looking at a larger increase this year, and then a far more moderate increase next year. Within that context, agencies will fare better or worse based on their current popularity.
SN: Are there any obvious winners or losers?
M.H.: We won’t really know that until the omnibus deal is released. All we have is an overall framework, but spending levels for individual agencies and programs will need to be negotiated and the details released. I would certainly expect more winners than losers, given how large a spending increase we’re talking about. The deal apparently includes some extra funding for NIH, though again we’ll see how the details look.
SN: Could the extra money still be cut?
M.H.: Whatever Congress does, they can, of course, undo. But if they lower the cap next year after raising it, it would be the first time. The downside is, this does add quite a bit to the deficit. With this deal plus the recent tax reform, we’re looking at a potential return to trillion-dollar deficits next year. When deficits get bigger, Congress gets more interested in restraining spending, and trillion-dollar deficits are what got us here in the first place. It’s a catch-22.
SN: How will Trump’s FY 2019 budget proposal impact how the money is divvied up?
M.H.: Last year’s budget proposed big cuts to nondefense spending, and now Congress has gone in the complete opposite direction. We’ll see what the administration does … but if they go for a repeat performance, we could be looking at a pretty irrelevant [Trump] budget.
No wounded left behind — not quite. Ants that have evolved battlefield medevac carry only the moderately wounded home to the nest. There, those lucky injured fighters get fast and effective wound care.
Insect colonies seething with workers may seem unlikely to stage elaborate rescues of individual fighters. Yet for Matabele ants (Megaponera analis) in sub-Saharan Africa — with a mere 1,000 to 2,000 nest mates — treating the wounded can be worth it, says behavioral ecologist Erik Frank at the University of Lausanne in Switzerland. Tales of self-medication pop up across the animal kingdom. For Matabele ants, however, nest cameras plus survival tests show insects treating other adults and improving their chances of survival, he and colleagues report February 14 in Proceedings of the Royal Society B. For treatment boosting others’ survival, Frank says, the closest documented example is humans.
In Ivory Coast, Frank studied Matabele ant colonies that staged three to five termite hunts a day. He and colleagues at the University of Würzburg in Germany published research last year showing that members of a hunting party carry injured comrades home. Frank took a closer look at rescues after he accidentally drove over a Matabele ant column crossing a road. Survivors “were only interested in picking up the ants that were lightly injured, and leaving behind the heavily injured,” he says. When Frank later set injured ants in front of columns trooping home from raids, injured ants minus two legs typically got picked up. Only once did an ant with five missing legs get a lift.
Ants that have lost two legs still have value to a colony, especially in a species where only about 13 new adults a day emerge from pupae. Four-legged ants regain almost the same speed that ants have on six legs, he says. In a typical hunting party, about a third of the ants have survived some injury, but most ants have at least four legs left.
How the ants triage a battlefield evacuation is shaped by the injured ants’ behavior, Frank says. Ants with only moderate injuries, such as two lost legs, emit “help me” pheromones. These ants tuck in their remaining legs and generally cooperate with the rescuers. Not so with ants more seriously hurt, who may not even give off pheromones. Rescuers still stop to investigate. But the seriously injured ants often flail around instead of cooperating, and the rescuers give up.
Frank also has seen ants act more severely injured than they truly are. If the returning fighters bypass them, “they will immediately stand up and run as fast as they can behind the others,” he says. “In humans, it’s a very selfish behavior.” For ants, predators lurk, and the colony benefits by finding the injured first. For injured raiders that do get home, another ant — usually not the carrier — steps in to treat the wound by repeatedly moving her mouthparts over it. When Frank isolated the ants to prevent this wound licking, about 80 percent of injured ants died. When he allowed ants an hour of treatment before isolating them, only 10 percent of them died.
Based on Frank’s observations, others who study ants are now wondering if they also have seen such rescue tactics. Andy Suarez of the University of Illinois at Urbana-Champaign wants another look at big Dinoponera australis that he’s frequently seen prowling for prey despite missing a limb. And Bert Hölldobler wonders whether weaver ants he has seen retrieving injured nest mates after battle were rescuing them. The usual interpretation has been cannibalism, says Hölldobler, at Arizona State University in Tempe.
Frank, however, used bright acrylic spots to track the fate of rescued Matabele ants. They weren’t for lunch.
Galaxies, stars, planets and life, all are formed from one essential substance: matter.
But the abundance of matter is one of the biggest unsolved mysteries of physics. The Big Bang, 13.8 billion years ago, spawned equal amounts of matter and its bizarro twin, antimatter. Matter and antimatter partners annihilate when they meet, so an even stephen universe would have ended up full of energy — and nothing else. Somehow, the balance tipped toward matter in the early universe. A beguiling subatomic particle called a neutrino may reveal how that happened. If neutrinos are their own antiparticles — meaning that the neutrino’s matter and antimatter versions are the same thing — the lightweight particle might point to an explanation for the universe’s glut of matter.
So scientists are hustling to find evidence of a hypothetical kind of nuclear decay that can occur only if neutrinos and antineutrinos are one and the same. Four experiments have recently published results showing no hint of the process, known as neutrinoless double beta decay (SN: 7/6/02, p. 10). But another attempt, set to begin soon, may have a fighting chance of detecting this decay, if it occurs. Meanwhile, planning is under way for a new generation of experiments that will make even more sensitive measurements.
“Right now, we’re standing on the brink of what potentially could be a really big discovery,” says Janet Conrad, a neutrino physicist at MIT not involved with the experiments. Each matter particle has an antiparticle, a partner with the opposite electric charge. Electrons have positrons as partners; protons have antiprotons. But it’s unclear how this pattern applies to neutrinos, which have no electric charge.
Rather than having distinct matter and antimatter varieties, neutrinos might be the lone example of a theorized class of particle dubbed a Majorana fermion (SN: 8/19/17, p. 8), which are their own antiparticles. “No other particle that we know of could have this property; the neutrino is the only one,” says neutrino physicist Jason Detwiler of the University of Washington in Seattle, who is a member of the KamLAND-Zen and Majorana Demonstrator neutrinoless double beta decay experiments.
Neutrinoless double beta decay is a variation on standard beta decay, a relatively common radioactive process that occurs naturally on Earth. In beta decay, a neutron within an atom’s nucleus converts into a proton, releasing an electron and an antineutrino. The element thereby transforms into another one further along the periodic table. In certain isotopes of particular elements — species of atoms characterized by a given number of protons and neutrons — two beta decays can occur simultaneously, emitting two electrons and two antineutrinos. Although double beta decay is exceedingly rare, it has been detected. If the neutrino is its own antiparticle, a neutrino-free version of this decay might also occur: In a rarity atop a rarity, the antineutrino emitted in one of the two simultaneous beta decays might be reabsorbed by the other, resulting in no escaping antineutrinos.
Such a process “creates asymmetry between matter and antimatter,” says physicist Giorgio Gratta of Stanford University, who works on the EXO-200 neutrinoless double beta decay experiment. In typical beta decay, one matter particle emitted — the electron — balances out the antimatter particle — the antineutrino. But in neutrinoless double beta decay, two electrons are emitted with no corresponding antimatter particles. Early in the universe, other processes might also have behaved in a similarly asymmetric way.
On the hunt To spot the unusual decay, scientists are building experiments filled with carefully selected isotopes of certain elements and monitoring the material for electrons of a particular energy, which would be released in the neutrinoless decay.
If any experiment observes this process, “it would be a huge deal,” says particle physicist Yury Kolomensky of the University of California, Berkeley, a member of the CUORE neutrinoless double beta decay experiment. “It is a Nobel Prize‒level discovery.”
Unfortunately, the latest results won’t be garnering any Nobels. In a paper accepted in Physical Review Letters, the GERDA experiment spotted no signs of the decay. Located in the Gran Sasso underground lab in Italy, GERDA looks for the decay of the isotope germanium-76. (The number indicates the quantity of protons and neutrons in the atom’s nucleus.) Since there were no signs of the decay, if the process occurs it must be extremely rare, the scientists concluded, and its half-life must be long — more than 80 trillion trillion years.
Three other experiments have also recently come up empty. The Majorana Demonstrator experiment, located at the Sanford Underground Research Facility in Lead, S.D., which also looks for the decay in germanium, reported no evidence of neutrinoless double beta decay in a paper accepted in Physical Review Letters. Meanwhile, EXO-200, located in the Waste Isolation Pilot Plant, underground in a salt deposit near Carlsbad, N.M., reported no signs of the decay in xenon-136 in a paper published in the Feb. 16 Physical Review Letters.
Likewise, no evidence for the decay materialized in the CUORE experiment, in results reported in a paper accepted in Physical Review Letters. Composed of crystals containing tellurium-130, CUORE is also located in the Gran Sasso underground lab.
The most sensitive search thus far comes from the KamLAND-Zen neutrinoless double beta decay experiment located in a mine in Hida, Japan, which found a half-life longer than 100 trillion trillion years for the neutrinoless double beta decay of xenon-136.
That result means that, if neutrinos are their own antiparticles, their mass has to be less than about 0.061 to 0.165 electron volts depending on theoretical assumptions, the KamLAND-Zen collaboration reported in a 2016 paper in Physical Review Letters. (An electron volt is particle physicists’ unit of energy and mass. For comparison, an electron has a much larger mass of half a million electron volts.)
Neutrinos, which come in three different varieties and have three different masses, are extremely light, but exactly how tiny those masses are is not known. Mass measured by neutrinoless double beta decay experiments is an effective mass, a kind of weighted average of the three neutrino masses. The smaller that mass, the lower the rate of the neutrinoless decays (and therefore the longer the half-life), and the harder the decays are to find.
KamLAND-Zen looks for decays of xenon-136 dissolved in a tank of liquid. Now, KamLAND-Zen is embarking on a new incarnation of the experiment, using about twice as much xenon, which will reach down to even smaller masses, and even rarer decays. Finding neutrinoless double beta decay may be more likely below about 0.05 electron volts, where neutrino mass has been predicted to lie if the particles are their own antiparticles.
Supersizing the search KamLAND-Zen’s new experiment is only a start. Decades of additional work may be necessary before scientists clinch the case for or against neutrinos being their own antiparticles. But, says KamLAND-Zen member Lindley Winslow, a physicist at MIT, “sometimes nature is very kind to you.” The experiment could begin taking data as early as this spring, says Winslow, who is also a member of CUORE.
To keep searching, experiments must get bigger, while remaining extremely clean, free from any dust or contamination that could harbor radioactive isotopes. “What we are searching for is a decay that is very, very, very rare,” says GERDA collaborator Riccardo Brugnera, a physicist at the University of Padua in Italy. Anything that could mimic the decay could easily swamp the real thing, making the experiment less sensitive. Too many of those mimics, known as background, could limit the ability to see the decays, or to prove that they don’t occur.
In a 2017 paper in Nature, the GERDA experiment deemed itself essentially free from background — a first among such experiments. Reaching that milestone is good news for the future of these experiments. Scientists from GERDA and the Majorana Demonstrator are preparing to team up on a bigger and better experiment, called LEGEND, and many other teams are also planning scaled-up versions of their current detectors.
Antimatter whodunit If scientists conclude that neutrinos are their own antiparticles, that fact could reveal why antimatter is so scarce. It could also explain why neutrinos are vastly lighter than other particles. “You can kill multiple problems with one stone,” Conrad says.
Theoretical physicists suggest that if neutrinos are their own antiparticles, undetected heavier neutrinos might be paired up with the lighter neutrinos that we observe. In what’s known as the seesaw mechanism, the bulky neutrino would act like a big kid on a seesaw, weighing down one end and lifting the lighter neutrinos to give them a smaller mass. At the same time, the heavy neutrinos — theorized to have existed at the high energies present in the young universe — could have given the infant cosmos its early preference for matter.
Discovering that neutrinos are their own antiparticles wouldn’t clinch the seesaw scenario. But it would provide a strong hint that neutrinos are essential to explaining where the antimatter went. And that’s a question physicists would love to answer.
“The biggest mystery in the universe is who stole all the antimatter. There’s no bigger theft that has occurred than that,” Conrad says.
The history of New England’s most damaging earthquake is written in the mud beneath a Massachusetts pond. Researchers identified the first sedimentary evidence of the Cape Ann earthquake, which in 1755 shook the East Coast from Nova Scotia to South Carolina. The quake, estimated to have been at least magnitude 5.9, took no lives but damaged hundreds of buildings.
Within a mud core retrieved from the bottom of Sluice Pond in Lynn, Mass., a light brown layer of sediment stands out amid darker layers of organic-rich sediment, the researchers report March 27 in Seismological Research Letters. The 2-centimeter-thick layer contains tiny fossils usually found near the shore, as well as types of pollen different from those found in the rest of the core. Using previous studies of the pond’s deposition rates, geologist Katrin Monecke of Wellesley College in Massachusetts and her colleagues determined the layer dates to between 1740 and 1810. That light-brown layer is likely a turbidite, sediment jumbled up by a sudden lake slope failure, the study says. There are no other turbidites in the core, which spans about 400 years, suggesting the slopes held fast through floods and hurricanes. But the Cape Ann quake was likely a strong enough trigger to cause the slope failure.
Though the eastern United States is not at the seismically active edge of a tectonic plate, it has occasionally had its ground-shakers (SN Online: 8/23/11). The study suggests other East Coast lakes and ponds may contain evidence of prehistoric quakes, giving researchers a new way to estimate their frequency.
The Cape Ann quake also left its mark on the colonists, inspiring poems that suggested the temblor was a warning from a wrathful God. Harvard University scientist John Winthrop chronicled witness accounts of the quake in a 1757 paper to the Royal Society of London. “The earthquake began with a roaring noise,” Winthrop quoted one man as saying, “like thunder at a distance.”
A famous 4.4-million-year-old member of the human evolutionary family was hip enough to evolve an upright gait without losing any tree-climbing prowess.
The pelvis from a partial Ardipithecus ramidus skeleton nicknamed Ardi (SN: 1/16/10, p. 22) bears evidence of an efficient, humanlike walk combined with plenty of hip power for apelike climbing, says a team led by biological anthropologists Elaine Kozma and Herman Pontzer of City University of New York. Although researchers have often assumed that the evolution of walking in hominids required at least a partial sacrifice of climbing abilities, Ardi avoided that trade-off, the scientists report the week of April 2 in the Proceedings of the National Academy of Sciences. “Ardi evolved a solution to an upright stance, with powerful hips for climbing that could fully extend while walking, that we don’t see in apes or humans today,” says Pontzer, who is also affiliated with CUNY’s Hunter College. Ardi’s hip arrangement doesn’t appear in two later fossil hominids, including the famous partial skeleton known as Lucy, a 3.2-million-year-old Australopithecus afarensis.
Ardi’s lower pelvis is longer than that of humans, which led some researchers to argue that Ardipithecus mainly climbed in trees and walked slowly with bent knees and hips, or perhaps not at all. But the new study shows it “would not have impeded its ability to walk upright in a humanlike fashion,” says paleoanthropologist Carol Ward of the University of Missouri in Columbia. Unlike other hominids and living apes, Ardi’s upper pelvis is positioned behind the lower pelvis, enabling a straight-legged gait, Pontzer and his colleagues find. An evolutionary reorienting of the pelvis in that way enabled back muscles to support an upright spine, Ward suggests. A relatively large gluteus maximus works with hamstring muscles to push humans into a straight-legged stance. Ardi may have had a small rear-end muscle for her size, making a forward-positioned lower pelvis especially critical for walking, Pontzer says.
Using previous data from present-day humans, chimps and monkeys, Pontzer’s group documented a relationship between the shape and orientation of the lower pelvis and the energy available for a range of motions involved in walking and climbing. They used those findings to examine fossil pelvises of Ardi, Lucy and a 2.5-million-year-old Australopithecus africanus. No other fossil hominids from that long ago included a pelvis complete enough for analysis.
The researchers also evaluated a nearly 18-million-year-old fossil pelvis from an African ape, Ekembo nyanzae.
A. afarensis and A. africanus displayed pelvic arrangements for upright walking, but not for Ardi’s apelike climbing power. In particular, the lower pelvis of the two Australopithecus species was nearly as short as the walking-specialized lower pelvis of people today. E. nyanzae’s pelvis was specialized for climbing, as in modern apes and monkeys. Its long, straight pelvis enabled walking with bent hips and knees.
The new study coincides with previous evidence that Ardi’s lower back was flexible enough to support straight-legged walking, says paleoanthropologist Owen Lovejoy of Kent State University in Ohio. Lovejoy, who led an initial investigation of Ardi’s lower-body bones, has long contended that ancient hominids had a humanlike gait (SN: 7/17/10, p. 5).
“A. afarensis and A. africanus walked much like we do, and for the most part that goes for Ardi as well,” Lovejoy says.
Ardi’s unusual mix of walking and climbing abilities spurred the evolution of hominid bodies geared toward minimizing lower-limb injuries, Lovejoy proposes. Ardi’s long lower pelvis and apelike, opposable big toe were replaced in Lucy’s kind by a short lower pelvis connected to smaller hamstring muscles, a humanlike big toe and a fully developed arch (SN: 3/12/11, p. 8). Those changes made climbing harder for A. afarensis, but stabilized its upright stance, helping to prevent foot injuries and hamstring tears when stopping suddenly or accelerating quickly, Lovejoy says.
Just like lions, tigers and bears, certain kinds of seals have claws that help the animals grasp prey and tear it apart. X-rays show that the bones in these seals’ forelimbs look like those found in the earliest seals, a new study finds.
Ancestors of these ancient seals transitioned from land to sea at some point, preserving clawed limbs useful for hunting on land. But clawed paws in these northern “true seals,” which include harbor and harp seals, seem to be more than just a holdover from ancient times, says David Hocking, a marine zoologist at Monash University in Melbourne, Australia. Instead, retaining the claws probably helps northern true seals catch a larger meal than they could with the stiff, slippery fins of other pinnipeds such as sea lions and fur seals, Hocking and his colleagues report April 18 in Royal Society Open Science. Hocking and his colleagues spent 670 hours observing wild harbor and gray seals hunting salmon in Scotland. Tests with three captive seals, two harbor seals born in captivity and one spotted seal born in the wild allowed the team to observe eating behaviors at closer range. While some of the captive seals seemed to prefer swallowing their prey whole, both the wild and captive animals relied heavily on their claws overall, the scientists found. The critters were frequently spotted using their slashers to hold onto prey and rip off smaller bites, much as a land animal like a wolverine or a bear might. Up-close observations revealed seals caught prey underwater, but ripped it apart at the surface. That probably lets them breathe while eating without inhaling gulps of seawater — a challenge when devouring a large meal underwater. Northern true seals have flexible joints that allow the animals to curl their claws to grasp prey. These flexible joints are also seen on early pinnipeds such as Enaliarctos mealsi, a seal that lived 23 million years ago, Hocking and his colleagues found. Fur seals and sea lions, however, “have inflexible fingers that help them to maintain a stiff flipper,” Hocking says.
The evolution of flipperlike forelimbs helped some pinnipeds propel themselves through the water more efficiently. But slippery flippers aren’t as useful for grasping prey. That could explain why fur seals and sea lions tend to target smaller fish that they can swallow whole underwater without needing to grasp, Hocking says.
But this fully aquatic feeding style might have been a challenge for the earliest pinnipeds, who probably used their clawed paws to hunt more like today’s true seals, the researchers say. Catching prey underwater and then shredding it at the surface was probably a smaller behavioral leap from full-on land feeding than other aquatic hunting strategies.
Documenting seals using their paws to grasp food is a “nice observation,” says Frank Fish, a biologist at West Chester University in Pennsylvania. Without knowing what early seals ate, though, it’s hard to say for sure whether they actively used their claws to hold onto large prey, he says.
Other scientists have documented true seals using their pawlike forelimbs in stereotypically terrestrial ways, too, such as using the claws to dig out lairs in ice or uncovering buried fish from the seafloor.
When it comes to tiny ocean swimmers, the whole is much greater than the sum of its parts. Ocean turbulence stirred up by multitudes of creatures such as krill can be powerful enough to extend hundreds of meters down into the deep, a new study suggests.
Brine shrimp moving vertically in two different laboratory tanks created small eddies that aggregated into a jet roughly the size of the whole migrating group, researchers report online April 18 in Nature. With a fluid velocity of about 1 to 2 centimeters per second, the jet was also powerful enough to mix shallow waters with deeper, saltier waters. Without mixing, these waters of different densities would remain isolated in layers. The shrimp represent centimeter-sized swimmers, including krill and shrimplike copepods, found throughout the world’s oceans that may together be capable of mixing ocean layers — and delivering nutrient-rich deep waters to phytoplankton, or microscopic marine plants, near the surface, the researchers suggest. “The original thinking is that these animals would flap their appendages and create little eddies about the same size as their bodies,” says John Dabiri, an expert in fluid dynamics at Stanford University. Previous work, including acoustic measurements of krill migrations in the ocean ( SN: 10/7/06, p. 238 ) and theoretical simulations of fluid flow around swimmers such as jellyfish and shrimplike copepods ( SN: 8/29/09, p. 14 ), had suggested that they may be stirring up more turbulence than thought. In 2014, Dabiri coauthored a study that debuted the laboratory tank setup also used in the new research. That paper noted that migrating brine shrimp created jets and eddies much larger than themselves. “But there was skepticism about whether those lab results were relevant to the ocean,” Dabiri says. The 2014 study didn’t account for how ocean water stratifies into layers that don’t easily mix, due to differences in salinity or temperature. It wasn’t clear if shrimp-generated turbulence could be strong enough and extend deep enough to overcome the physical barriers and mix the layers.
The new research used a 1.2-meter-deep tank and a 2-meter-deep tank. Each held tens of thousands of wiggly brine shrimp in two layers of water of different densities. The researchers used LED lights to prompt the shrimp to migrate upward or downward, mimicking the massive daily, vertical migrations of krill, copepods and other ocean denizens. The shrimp migrated in close proximity to one another – and that helped to magnify their individual efforts, the scientists found.
“As one animal swims upward, it’s kicking backward,” Dabiri says. That parcel of water then gets kicked downward by another nearby animal, and then another. The result is a downward rush that gets stronger as the migration continues, and eventually extends about as deep as the entire migrating group. In the ocean, that could be as much as hundreds of meters.“At the heart of the investigation is the question about whether life in the ocean, as it moves about the environment, does any important ‘mixing,’ ” says William Dewar, an oceanographer at Florida State University in Tallahassee. “These results argue quite compellingly that they do, and strongly counter the concern that most marine life is simply too small in size to matter.”
The team’s finding opens the door to a host of interesting questions, Dewar adds. Ocean mixing is an important part of the global climate cycle: It churns up nutrients that feed phytoplankton blooms and aids the exchange of gases with the atmosphere. Adding biologically driven mixing to physical processes in the ocean makes the equation even more complex, he says.
The next step will be to try to observe the effect at sea, using shipboard measurements, Dabiri says. “Previous studies looked for turbulence or eddies on the scale of the animals’ size,” he says, instead of large downward jets. “This paper tells us for the first time what to look for.”
Shooting small rocks from a high-speed cannon showed that some asteroids could have brought water to the early Earth — without all the water boiling away on impact, a new study finds.
“We can’t bring an asteroid to Earth and crash it into the Earth, bad things would happen,” says planetary geologist R. Terik Daly, who did the research while a graduate student at Brown University in Providence, R.I. “So we went into the lab and tried to re-create the event as best we can.” After the solar system formed about 4.6 billion years ago, Earth grew up relatively close to the sun, where it was too hot for water to condense out of the gas phase. And Earth was too small to hold on to much nearby gas anyway. So scientists think the pale blue dot may have received its water from somewhere else — although exactly how that happened is still up for debate (SN: 5/16/15, p. 18).
Daly, now at Johns Hopkins University, and Brown planetary scientist Peter Schultz made marble-sized pellets of antigorite, a mineral found in Japan that is similar to the kinds of rocks that may have brought water to Earth billions of years ago. To simulate a dry planetary surface, the team baked pumice at 850° Celsius for 90 minutes. Then the team shot the pellets at the pumice at about 5 kilometers per second using the NASA Ames Vertical Gun Range in California. That speed is similar to those at which asteroids probably crashed into each other when the planets were forming, Daly says. Previous simulations suggested that all of an asteroid’s water would vaporize upon impact if the asteroid had been traveling faster than 3.1 kilometers per second. On a planet like the early Earth, which lacked an atmosphere, that water vapor would then have been lost to space. But Daly and Schultz found that some of the water vapor released by the pellets’ impacts was captured within glass created from shocked rock, or conglomerates of “busted-up” rocks called breccias. Asteroids could have delivered up to 30 percent of their stored water to growing planets, the scientists conclude April 25 in Science Advances. The next step is working out how the water could escape from rocks to create oceans and other water bodies, Daly says.
“I really like this work,” says planetary scientist Yang Liu of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who was not involved in the study. “The experimental setup is very clever.”
Liu studies water in lunar material, and one frequent question about her work is how the moon can have water at all (SN: 10/24/09, p. 10). Earth’s nearest celestial neighbor lacks a thick atmosphere where vapor can accumulate, which means the moon should have had an even harder time keeping impact-delivered water than the Earth did.
“This work demonstrates that this is feasible even for airless bodies,” she says. The finding even suggests a way for future crewed missions to find water on the moon: “Perhaps we should just look for impact melts to get the water we need.”
Animal experiments demonstrate for the first time that transplanted tumors release a chemical into the host’s bloodstream that causes the host to produce blood vessels to supply the tumor.… If such a factor can be identified in human cancers … it might be possible to prevent the vascularization of tumors. Since tumors above a certain small size require a blood supply to live, they might by this method be starved to death. — Science News, May 4, 1968
Update By the 1990s, starving tumors had become a focus of cancer research. Several drugs available today limit a tumor’s blood supply. But the approach can actually drive some cancer cells to proliferate, researchers have found. For those cancers, scientists have proposed treatments that open up tumors’ gnarled blood vessels, letting more oxygen through. Boosting oxygen may thwart some cancer cell defenses and promote blood flow — allowing chemotherapy drugs and immune cells deeper access to tumors (SN: 3/4/17, p. 24).
The world tracked the New Horizons’ spacecraft with childlike glee as it flew by Pluto in 2015. The probe provided the first ever close-up of the place that many of us grew up considering the ninth planet. Pluto revealed itself as a fascinating world, with a shifting surface (SN: 12/26/15, p. 16), a hazy atmosphere (SN Online: 10/15/15) and a heart of nitrogen ice (SN Online: 9/23/16). But the course of space exploration never did run smooth. In Chasing New Horizons, Alan Stern — New Horizons’ principal investigator and chief champion — and his coauthor, team member David Grinspoon, share their recollections of how a band of scrappy planetary scientists got a mission to the farthest reaches of the solar system off the ground. Over the course of a decade and a half, Stern and colleagues in the “Pluto Underground” fought first to get a Pluto mission taken seriously by NASA, then to keep it alive through budget woes, political battles, stiff competition from other mission proposals and outright cancellations.
Even if you followed the flyby closely and think you know this story, the book divulges details that will surprise you. Come for the sweeping tale of wonder and exploration; stay for the gaggle of planetary scientists celebrating on Bourbon Street once their mission finally got the green light.
Science News talked with Stern about the book, what it’s like to be “Mr. Pluto” and what’s next for New Horizons, which is currently in hibernation cruising through the Kuiper Belt. The interview that follows has been edited for length and clarity. SN: Almost half of the book is about the fight to get the New Horizons mission approved. Why was it important for you to focus on that? Stern: If you look at the 26-year span, from 1989 [the year the American Geophysical Union meeting devoted the first conference session to the subject of a Pluto mission] to 2015 when we got there, almost precisely half of that time was back and forth trying to get a mission to Pluto.
It’s rare for the public to get to see the behind the scenes of how difficult it is — how much competition there is, how many things come out of left field, how much scientists with a goal or objective in mind really have to have persistence to make it happen.
SN: You write that by the time the mission teams were being assembled, you were already known as Mr. Pluto. When did you start feeling like Mr. Pluto yourself?
Stern: Somewhere in the ʼ90s, when we were going through this maze of twists and turns to get a mission to Pluto. Every time we’d have a reversal, and I’d have to go fight for it again, I started to feel like I was putting on my Mr. Pluto hat.
I’m typecast that way now. You know, I’ve been on 29 different space missions, to almost every planet in the solar system. Only one of them was to Pluto, but that’s the one, maybe the only one, I’m known for. It’s like being on the cast of Gilligan’s Island, they only remember you for the one thing, no matter how much else you’ve done. Which is fine [laughs]. I love Pluto, no question, but it’s not like that’s all I did in the past three decades.
SN: What’s next for New Horizons?
Stern: We emerge from an almost six-month hibernation period on June 4. Our next flyby is taking place on New Year’s Eve and New Year’s Day with a small Kuiper Belt object that we’ve nicknamed Ultima Thule, which is a building block of planets like Pluto.
It’s going to just be spectacular, scientifically. And so our team is really up to our eyeballs in flyby planning and preparations.
SN: How long can the spacecraft keep going after that?
Stern: New Horizons has the fuel and power to go on for decades, and it’s very healthy. And there’s a lot more science to do in the Kuiper Belt. In fact, there is some science that the spacecraft is capable of doing that no other spacecraft can. There are some kinds of unique astrophysics that even the James Webb [Space Telescope, due to launch in 2020] and the Hubble can’t do, that we can do.
New Horizons is really is an amazing resource. There’s no other spacecraft planned to fly to these great distances again. So we want to make sure that science benefits to the maximum extent.
SN: There’s a scene in the book, right before the Pluto flyby, when a journalist asks how you’re going to feel at the end of the mission — will there be a sort of grief at the culmination of all this work. Now that you’re on the other side, how does it feel?
Stern: A lot of people in the mission team, as we were finally bearing down on Pluto, started to express that kind of concern. Frankly, we’d been so busy I didn’t have time to think philosophically about “what after.” I was thinking about catching up on my sleep, seeing my family more, what discoveries would we make. But I wasn’t thinking about, what do you do after your Apollo 11? What do you do after you’ve scaled your Everest?
As it turns out, a lot of those concerns just sort of washed away with the success of the flyby and the spectacular scientific discoveries at Pluto. Now I and other people on our team look back on it and say, “I was a part of something that really made a difference.” You can’t ask for much more than that.
