Giant squid are the stuff of nightmares. They were even one of the deadly dangers in Jules Verne’s 20,000 Leagues Under the Sea, attacking the Nautilus in a group and carrying off one of the crew:

Just as we were crowding each other to reach the platform, two more arms lashed the air, swooped on the seaman stationed in front of Captain Nemo, and carried the fellow away with irresistible violence…. What a scene! Seized by the tentacle and glued to its suckers, the unfortunate man was swinging in the air at the mercy of this enormous appendage. He gasped, he choked, he yelled: ‘Help! Help!’ … The poor fellow was done for.

What makes Verne’s giant squid all the more frightening is that he didn’t invent the creatures; giant squid strandings had been documented in Europe since at least 1639, and scientists informally described the animals in the late 1850s.

But even if we don’t really have to worry about the huge invertebrates snatching people off boats, giant squid remain mysterious. They weren’t even photographed in the wild until 2004. And many questions remain unanswered about them. The biggest: Just how giant can the giants get? A new study has come up with an estimate — and also highlights the many reasons why it’s so difficult to come up with one.

Charles Paxton of the University of St. Andrews in Scotland starts by laying out five ways that it should be possible to estimate squid length, and why the first four aren’t great measures. Anecdotal accounts — which claim giant squid reaching lengths of 30 meters and 53 meters, not counting the two long tentacles — are often riddled with inaccuracy and exaggeration. Estimating maximum length based on squid growth rate won’t work because squid growth rates just aren’t well known. Some scientists have tried to determine lengths based on the sucker scars found on whales, but since scientists don’t know how whale growth affects the sizes of those scars, those aren’t a good measure either.

Direct measurement of dead squid would seem to be a good option, except that the two long tentacles of a squid — which extend far beyond the animal’s arms and determine its full length — are elastic and can change in length when a squid is preserved, Paxton notes. That leaves the fifth method — estimating length based on the size of the hard beak. Beak size and squid body length are related.

Paxton combined the last two methods to come up with a maximum length for a giant squid of about 20 meters, from the top of its mantle, or body, to the tip of its long tentacles. His estimate appears May 17 in the Journal of Zoology.
The longest squid ever reported was 17.37 meters long, and Paxton questions its veracity, as does another paper published last year in PeerJ. Craig McClain of Duke University and colleagues note that the “longest scientifically verified giant squid” measured a mere 12 meters. “What limits the large size of [giant squid] is unclear,” McClain and colleagues write. But metabolic demands may play a role, keeping squid from getting much bigger than what have washed up onto shore (and also keeping them in the cold depths where they’re so difficult for us to find).

But perhaps the focus on the largest and biggest of species is the wrong approach, McClain and his colleagues argue (in, ironically, a paper all about large marine species). The longest, most giant individuals are, after all, just a tiny fraction of a species — and, these researchers write, “these individuals may reach these extraordinary large sizes through developmental or genetic defects and may not represent the healthiest or, in evolutionary terms, the fittest.”

They are, though, among the most mysterious creatures to inhabit our planet.

From California to China, desert moss (Syntrichia caninervis) braves life in hot deserts and still stays hydrated. What’s its secret? The moss gathers water via a topsy-turvy collection system in its leaves.

Moss leaves have tiny hairlike points at their ends called awns. Previous evidence pointed to a potential role for the awns in water collection and prompted Tadd Truscott of Utah State University and his colleagues to zero in on the structures.

Imaging exposed a system of barbs that line the awns and catch tiny airborne water droplets, the team reports June 6 in Nature Plants. When the air is misty, foggy or the least bit humid, trapped dewdrops move up grooves in the moss leaves by capillary action. The tiny drops form a bigger drop to be absorbed and stored by the plant. When it rains, moss awns reduce splash and capture raindrops by the same mechanism.

Most desert plants, especially cacti, get their water from roots, but moss may not be the only plant that uses unique leaf structures to stock up on water, the team argues.

For the second time, scientists have glimpsed elusive ripples that vibrate the fabric of space. A new observation of gravitational waves, announced by scientists with the Advanced Laser Interferometer Gravitational-Wave Observatory, LIGO, follows their first detection, reported earlier this year (SN: 3/5/16, p. 6). The second detection further opens a new window through which to observe the universe.

“The era of gravitational wave astronomy is upon us,” says astronomer Scott Ransom of the National Radio Astronomy Observatory in Charlottesville, Va., who is not involved with LIGO. “Now that there’s two, you can’t get around that anymore.”

Both sets of cosmic quivers were wrought in cataclysmic collisions of black holes. But the latest observation indicates that such merging pairs of black holes are a varied bunch — the newly detected black holes were much smaller than the first pair. And this time, scientists concluded that one in the pair was spinning like a top.
“The most important thing is that it’s a second one,” says LIGO spokesperson Gabriela González of Louisiana State University in Baton Rouge. “But it’s important that it’s different, because it shows that there’s a spectrum of black hole systems out there.”

The two black holes in the most recent detection were about eight and 14 times the mass of the sun and were located roughly 1.4 billion light-years from Earth, the scientists estimate. When the pair fused, they formed one bloated black hole with a mass 21 times that of the sun. One sun’s worth of mass was converted into energy and carried away by the gravitational waves, LIGO scientists announced June 15 in San Diego during a meeting of the American Astronomical Society.
“Gravitational astronomy is real,” LIGO laboratory executive director David Reitze said in a news conference. “The future is going to be full of binary black hole mergers for LIGO.”

A paper describing the finding was published online June 15 in Physical Review Letters.

As the two black holes spiraled around each other and slammed together, they churned up cosmic undulations that stretched and squeezed space — as predicted by Einstein’s general theory of relativity. These waves careened across the universe, reaching LIGO’s twin detectors in Hanford, Wash., and Livingston, La., on December 26, 2015.

Each L-shaped LIGO detector senses the minuscule stretching and squeezing of space across its two 4-kilometer arms. As a gravitational wave passes through, one arm lengthens while the other shortens. Laser light bouncing back and forth in the arms serves as an ultrasensitive measuring stick that can pick up those subtle length changes (SN: 3/5/16, p. 22). As the gravitational waves rumbled past Earth in December, they stretched and squeezed the arms by less than a thousandth the width of a proton. “That’s very, very small,” González said. “That’s like changing the distance between Earth and the sun by a fraction of an atomic diameter.” This tiny deviation, appearing in both detectors nearly simultaneously, was enough to pick out the telltale ripples.

Compared with LIGO’s previously detected black hole merger, this one was a more minor dustup. These black holes were less than half the size of those in the first merger (30 and 35 solar masses according to a recently revised estimate). And the signal of their coalescence was more subtle, hiding under the messy wiggles in the data that result from random fluctuations or unwanted signals from the environment.
The first detection stunned scientists, due to the surprisingly large masses of the black holes and the whopping signals their gravitational waves left in the data. But the new black hole merger is more in line with expectations.
“This is comfort food,” says physicist Emanuele Berti of the University of Mississippi in Oxford, who is not involved with LIGO. “If you had asked me before the first detection, I would have bet that this would have been the first kind of binary black hole to be observed, not the monster we saw.”

There’s little question about whether the signal is real — a false alarm of this magnitude should occur only once in 200,000 years. “It’s very, very exciting,” says physicist Clifford Will of the University of Florida in Gainesville. It “looks like a very solid discovery.”

In a new twist, the scientists found that one of the two merging black holes was spinning. It was rotating at a speed at least 20 percent of its maximum possible speed. Using gravitational waves to study how pairs of black holes twirl could help scientists understand how they form.

The scientists used their data to put general relativity through its paces, looking for deviations from the theory’s predictions. But the black holes’ behavior was as expected.

LIGO also saw hints of a third black hole collision on October 12. The evidence was not strong enough to claim a definitive detection, though.

LIGO is currently offline, undergoing improvements that will allow the detectors to peer even further out into space. Scientists expect it to be back up and running this fall, churning out new detections of gravitational waves. “Now we know for sure that we’ll see more in the future,” González says.

AUSTIN, TEXAS — Success of an indoor spraying campaign to combat malaria on an African island may have started a worrisome trend in local mosquito evolution.

Since 2004, using pesticides inside homes has eradicated two of four malaria-spreading Anopheles mosquitoes on Bioko Island in Equatorial Guinea, vector biologist Jacob I. Meyers of Texas A&M University in College Station reported June 19 at the Evolution 2016 meeting. Numbers of the remaining two species have dropped. Yet the dregs of these supposedly homebody species are showing a rising tendency to fly outdoors looking for a blood meal, Meyers and colleagues cautioned. The results were also reported April 26 in Malaria Journal.

If the mosquitoes continue to shift toward outside bloodsucking, the campaign could lose some of its bite. Repeated treatments of indoor walls with pesticides that kill mosquitoes clinging to them may not be so effective if the pests venture from home.

What’s changing about these mosquitoes remains to be seen, but this looks like more than simple opportunism, Meyers said. Bed nets are not common, so Meyers doubts that the mosquitoes fly outdoors because no one is available to bite indoors. Nor does their reaction look like escape from repellent pesticides: Outdoor biting didn’t consistently rise after a spraying. The next step is to check for a genetic basis for the shift. Lots of research has explored physiology that lets insects resist pesticides, Meyers said, but the onset of possible resistant behavior has barely been explored.

Bottoms up, from the distant past. Thanks to a new method of analyzing the chemicals in liquids absorbed by clay containers, researchers have uncorked the oldest solid evidence of grape-based wine making in Europe, and possibly the world, at a site in northern Greece.

Chemical markers of red wine were embedded in two pieces of a smashed jar and in an intact jug discovered in 2010 in the ruins of a house destroyed by fire around 6,300 years ago at the ancient farming village of Dikili Tash.
After successfully testing the new technique on replicas of clay vessels filled with wine, then emptied, the scientists identified chemical markers of grape juice and fermentation in clay powder scraped off the inner surfaces of the Dikili Tash finds. None of the vessels contained visible stains or residue, researchers report online May 24 in the Journal of Archaeological Science.

Remains of crushed grapes found near the ancient jar shards and jug had already indicated that Dikili Tash farmers made wine or grape juice, say chemist Nicolas Garnier of École Normale Supérieure in Paris and archaeobotanist Soultana Maria Valamoti of Aristotle University of Thessaloniki in Greece.

Previous reports of ancient wine have largely relied on chemical markers of grapes but not the fermentation necessary to turn them into wine, leaving open the possibility that containers held grape juice. The “juice versus wine” conundrum applies to roughly 7,400-year-old jars from Iran (SN: 12/11/04, p. 371), Garnier says.

Homo naledi, currently the best-known and most mysterious fossil species in the human genus, may be considerably younger than previously thought, a new investigation suggests.

Evolutionary trees of ancient hominids statistically reconstructed from skull and tooth measurements indicate that H. naledi lived around 912,000 years ago, say paleoanthropologist Mana Dembo of Simon Fraser University in Burnaby, Canada, and her colleagues. That’s a provisional estimate, since researchers have yet to date either H. naledi’s bones or the sediment in which some of its remains were excavated.
The new statistical age estimate, described by Dembo’s group in the August Journal of Human Evolution, challenges proposals that H. naledi’s remains come from early in Homo evolution. Researchers who first studied H. naledi bones retrieved from an underground cave in South Africa noted similarities of the skull and several other body parts to early Homo species dating to between 2.5 million and 1.5 million years ago (SN: 10/3/15, p. 6).

A comparison of H. naledi skull measurements to those of 10 other hominid species, conducted by paleoanthropologist J. Francis Thackeray of the University of the Witwatersrand in Johannesburg, reached the same conclusion. H. naledi lived roughly 2 million years ago, Thackeray proposed in the November/December 2015 South African Journal of Science.

Dembo disagrees. Her team tested which of 60,000 possible evolutionary trees best fit skull and tooth measurements of H. naledi, 20 other hominid species, gorillas and chimpanzees. The new analysis keeps H. naledi in the genus Homo. But it’s still unclear which of several hominid species — including Homo sapiens, Homo floresiensis (or “hobbits”) and Australopithecus sediba (SN: 8/10/13, p. 26) — is most closely related to the South African species.

Dembo’s team found no signs that bones assigned to H. naledi represent a variant of Homo erectus, as some scientists have argued. H. erectus originated about 1.8 million years ago in Africa and rapidly spread to West Asia. But Dembo’s statistical model assumes that H. erectus skulls and teeth vary in shape throughout Africa and Asia much less than they actually do, says paleoanthropologist Christoph Zollikofer of the University of Zurich. Bones assigned to H. naledi most likely represent a form of H. erectus, he argues.

Further statistical comparisons that include measurements of limb and trunk bones may help to clarify H. naledi’s evolutionary relationships, Dembo says.
Based on geological dates for all hominids except H. naledi, the researchers also calculated the rate at which each species’ skull and tooth features evolved over time. Those results enabled the researchers to estimate H. naledi’s age.

“Homo naledi might be less than a million years old,” Dembo says. She considers that estimate “reasonably robust,” since ages calculated for other hominids in the analysis often fell close to dates gleaned from fossil and sediment studies. In a few cases, though, statistical and geological age estimates differed by 800,000 years or more.

A relatively young age for H. naledi expands the number of Homo species that survived well into the Stone Age, Dembo says. Small-brained H. naledi would have existed at the same time as larger-brained Homo species in Africa, just as small-brained H. floresiensis lived at the same time as larger-brained H. sapiens and H. erectus in Southeast Asia (SN: 7/9/16, p. 6).

If that scenario holds up, H. naledi may have made roughly 1-million-year-old stone tools that have been found in southern Africa, Dembo says.

“A young date for Homo naledi shouldn’t be unexpected,” says paleoanthropologist Matthew Tocheri of Lakehead University in Thunder Bay, Canada. At least some H. naledi bones appear not to have fossilized, he notes, consistent with a more recent age.

While Dembo’s statistical approach to hominid evolution shows promise, “a good geological date for H. naledi will trump the new date,” Tocheri adds.

Paleoanthropologist Bernard Wood of George Washington University in Washington, D.C., doesn’t think Dembo’s approach can accurately date H. naledi. But humanlike hands, feet and teeth of the South African hominid support the possibility that it lived about 1 million years ago, Wood says.

Two H. naledi researchers — John Hawks of the University of Wisconsin–Madison and Witwatersrand’s Lee Berger — still suspect the South African species lived at least 1.8 million years ago, based on its skeletal similarities to H. erectus. But a possible age of about 900,000 years for the cave finds, as proposed by Dembo, would be consistent with H. naledi or closely related species having survived in Africa for a million years or more, Hawks and Berger write in the current Transactions of the Royal Society of South Africa.

In our teens and 20s, many of us feel unstoppable. But after age 30, everyday life starts to get a little harder. Knees ache, hangovers last two days, younger family members begin to outrun us and we can’t remember what we did with our keys. With aches, pains and busy schedules, exercise can be a low priority, especially when it won’t necessarily help our waistlines. But exercising as we age can help preserve muscle mass so we can go the distance. It can even help us remember our keys.

After we hit 35, most of us just aren’t as strong or as fast as we used to be. “In normal aging there are a lot of physiological things that happen that decrease performance over the years,” explains Myriam Paquette, an exercise physiologist at Laval University in Quebec City. She notes that the maximum amount of oxygen we can use (VO2 max) and our overall muscle mass decrease, and, along with them, the strength and power they provide.

Exercise training can keep some of these effects at bay. “As soon as you hit 35 or 40, you need to start doing resistance [exercise],” says John Hawley, an exercise physiologist at Australian Catholic University in Sydney. “You muscles are being remodeled constantly. “As the muscle gets older … it gets resistant to building up.” So the older people get, the harder they have to work to get — and keep — their gains.

For VO2 max, decreases in maximum oxygen can mean decreased athletic performance. But “if people do high intensity training, that can be delayed five to 10 years,” says Michael Joyner, a physiologist at the Mayo Clinic in Rochester, Minn.

Enough exercise can even keep older athletes racing with the pros — as long as they run far enough. Sian Allen and Will Hopkins at the Sports Performance Research Institute New Zealand in Auckland gathered studies of peak competitive performance and found that for elite athletes, peak performance age increased as distance increased. Athletes who compete in short swimming events tended to peak at 20, while ultra-distance cyclists peaked at 39, they reported in the June 2015 Sports Medicine. Some of this may be for social reasons, Joyner notes — until the past few decades, distance events didn’t have the focus or coaching (or funding) that is characteristic of sprint distances.

Older athletes may not be at peak VO2 max and muscle mass, but they can take advantage of something only age provides — experience. “Being able to react to changes in conditions, mental resilience, pacing strategies, these are things you are able to accumulate,” Allen says. She suggests that learning and experience may assist people competing at later ages across longer distances, “As opposed to shorter distances that…[are] more raw expression of power.”

Age also takes a toll on the brain. This isn’t just for the retirees: Word recall, spatial reasoning and even processing speed can begin to decline in the early 30s. One of the brain benefits of exercise is an increase in the birth of new brain cells. As we get older, exercise proves protective both for brain structure and function. Sedentary people show decreases in white and gray matter as they age. Physical activity, even walking 72 blocks per week, helps preserve gray matter in older adults in areas such as the hippocampus — a brain area important for memory. Keeping up aerobic activity also improves cognitive control in middle-aged and older people — including tasks such as planning and working memory.
Some of this might be associated with the fact that keeping up aerobic activity means retaining VO2 max, says Takashi Tarumi, an exercise physiologist at the University of Texas Southwestern Medical Center in Dallas. Middle-aged endurance athletes with higher VO2 max also have better brain blood flow. That better blood flow is associated with better performance in memory and attention tasks — key to remembering where exactly you put those keys. Tarumi and his colleagues published their results in a 2013 study in the Journal of Hypertension.

While working out for weight loss or a beach body may be an exercise primarily in frustration, exercise is far from fruitless. It’s an investment toward stronger muscles and better endurance — whether for marathons or getting up the stairs. And staving off cognitive decline is probably well worth a few hours in the gym.

In the space business, weight and size are what run up the bills. So imagine the appeal of a telescope that’s a tenth to as little as a hundredth as heavy, bulky and power hungry as the conventional instruments that NASA and other government agencies now send into space. Especially alluring is the notion of marrying the time-tested technology called interferometry, used in traditional observatories, with the new industrial field of photonics and its almost unimaginably tiny optical circuits.

Say hello to SPIDER, or Segmented Planar Imaging Detector for Electro-optical Reconnaissance.
But its inventors believe that, once demonstrated at full-scale, SPIDER will replace standard telescopes and long-range cameras in settings where room is scarce, such as on planetary probes and reconnaissance satellites.

Researchers at the Lockheed Martin Advanced Technology Center in Palo Alto, Calif., with partners in a photonics lab at the University of California, Davis, have described work on SPIDER for several years at specialty conferences. In January, they revealed their progress with a splash to the public in a press release and polished video.

Somewhat like a visible-light version of a vast field of radio telescopes, but at a radically smaller scale, a SPIDER scope’s surface would sparkle with hundreds to thousands of lenses about the size found on point-and-shoot cameras. The instrument might be a foot or two across and only as thick as a flat-screen TV.

Transit system for light
SPIDER probably won’t be equivalent to a large instrument such as the Hubble Space Telescope, but it could be a smaller, lighter alternative to modest telescopes and long-range cameras. Experts tend to rank telescopes by their aperture — the size of the bucket that catches light or other such radiation. The wider the bucket’s mouth, the higher the resolution. Ordinarily, behind the bucket’s maw is an extensive framework for massive lenses, mirrors and heating or cooling systems. Hubble’s aperture spans 2.4 meters; its power-generating solar panels enlarge it to the size and weight of a winged city bus. Even a compact telescope with a saucer-sized lens might have more than a kilogram of equipment stretched behind its face for a third of a meter or so.
Alan Duncan, a senior fellow at Lockheed Martin’s Advanced Technology Center, has devoted much of his career to space and reconnaissance imaging. He often focuses on interferometry, a method astronomers have long used to combine electromagnetic waves — both radio and visible — from several different telescopes. The results, with the help of computers, are images more sharply focused than from any of the smaller telescopes or radio dishes. Yet even with the leverage of conventional interferometry, Duncan struggled to slash the SWaP: size, weight and power demand.

His ambitions leapt at the Photonics West 2010 meeting in San Francisco. He learned that IBM researchers had a supercomputer design that would need relatively little energy to cool its electronic innards. They proposed finely laced channels through which data-filled beams of light would travel to deliver the computer’s output data. The setup would require a fraction of the energy of standard, integrated electronic chips that use metal wiring.
Duncan stared at the skeins of optical channels and the millions of junctions portrayed on the screen during the IBM talk. He recalls seeing “about as many optical interconnects as a digital camera has pixels.” (A point-and-shoot camera’s pictures can have several megapixels, or millions of individual dots.) He imagined turning IBM’s tactic on its head. “They create photons in the chip, impose information on them and send them out to be decoded. What if you captured the light waves on the outside?” Duncan says. “The photons already have the [image] information you want.… You have to decode it inside the device. The decoder is the interferometer.”

The IBM people had not designed an interferometer, of course, but their optical circuitry seemed sophisticated enough to be adaptable to interferometry. Duncan figured that the fast-growing photonics industry already had or would soon invent fabrication solutions that his suddenly imagined telescope could use. Already, photonics companies were selling machines to create transparent channels or waveguides only a few millionths of a meter wide.

Considerably smaller than the fibers bundled into fiber-optic cables that carry data across continents and under oceans, photonic waveguides are made by finely focused, pulsating laser beams. As the beams scan along inside silicon-based photonic integrated circuits, or PICs, they leave behind close-packed strings in molten silicon that swiftly merge and cool. The resulting trails of transparency are superb transit systems for light, and they can be laser-incised in any pattern desired. Similar wizardry can shrink the scale of other optical gadgetry, such as filters to sort the signals by color, or the interferometry gadgetry to mix signals from different lenses in a SPIDER scope.

Decoding fringes
Interferometry does not produce pictures the way a conventional telescope does. Telescopes refract a scene’s incoming light through lenses or bounce it off of mirrors. The lenses or mirrors are shaped so that light beams, or photons, from a given part of a scene converge on a corresponding place on a photo-sensitive surface such as an image chip of a digital camera, similar to the retina of an eye.

Interferometry, instead, gathers signals from pairs of receivers — sometimes many pairs — all aimed at the same scene. It combines the signals to reveal the slight differences in the phases and strengths of the radio, light or other waves. The separate wave trains, or signals, are projected on a screen in an interferometry chamber as patterns of light and dark fringes where the signals from the paired receivers reinforce or counteract each other. The fringes, somewhat resembling checkout counter bar codes, carry a distinct, encoded hint of the difference in the viewed object as seen from the receivers’ offset positions in the aperture. With enough measurements of fringes from enough pairs of waves gathered by enough small receivers, a computer can deduce a picture that is as sharp as from a telescope with a lens as wide as the distance between the most widely spaced lenses, for example, on a SPIDER’s face.
Building a tiny version of this using photonics requires separate sets of waveguides for different colors or “spectral bins.” The more bins used, the more accurately an object can be portrayed. But each such layer of complexity aggravates the chore of fabrication.
So even a bare-bones SPIDER may need thousands of waveguides. Advanced SPIDERs may have millions of them. As far as Duncan knows, SPIDER would be the most complicated interferometer ever made.

Spycraft and space views
After his epiphany, Duncan began working with Lockheed colleagues, chiefly technology expert Richard L. Kendrick. Computed simulations convinced them that their mini-interferometer should work. In 2012, Lockheed Martin filed for a patent — granted in late 2014 — naming the two men as the inventors. Reflecting the company’s defense ties, the document provides a hypothetical application: SPIDER in a proposed, high-altitude Pentagon recon drone called Vulture, perhaps built into the curved bottom of a wing.

Initial simulations showed how SPIDER’s pictures of one satellite taken from another, or of buildings as seen from space, compare with pictures by standard long-range cameras. Interferometric images, due to the complex calculations using the equations of Fourier transforms, often have extra flares and streaks. Nonetheless, to a layman’s eye, the simulated SPIDER images look about the same as equivalent ones from standard lens or mirror telescopes.

If SPIDER pans out, its inventors imagine uses beyond spycraft. NASA is planning a mission to orbit Jupiter’s moon Europa (SN Online: 5/26/15). The SPIDER team calculates that, given the same space that has already been assigned to a conventional imager, SPIDER’s instrument could inspect 10 times the terrain at 17 times better resolution. SPIDER should be able to have a wider array of lenslets — or receivers — take pictures at points farther from Europa on the craft’s elliptical orbit and should have a wider field of view.

One proposed design for the first fully operable, but spartan, SPIDER is to have 37 radial blades, each backed by a single photonic chip with 14 lenslets along one edge. The whole model would be about the size of a dinner plate. Eventually, a SPIDER might be built on the face of a single chip of similar or larger size. This would allow more lenslets to be fitted, and permit waveguides to pair them up from anywhere in the aperture. Upshot: more “eyes” packed into the same space.
The Lockheed group has begun to fabricate test components in partnership with a photonics laboratory led by Ben Yoo, professor of electrical and computer engineering at UC Davis. DARPA, the Department of Defense’s agency for funding advanced research, granted about $2 million for prototype photonic integrated circuits and other gear to test the idea’s feasibility.

The technical challenges are extreme. Each tiny lenslet could need 200 or more separate waveguides leading from its focal area to the interferometers. For a fairly simple SPIDER scope, that would mean tens of thousands of waveguides coursing through the chips’ insides — perhaps fabricated many layers deep. So far, the researchers have built prototype components with only four lenslets, too few to get images.

Skeptics and a crusader
At least one top authority says the scheme is nonsense. Others are more amused than critical. Michael Shao, an MIT-trained astronomer and project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., has extensive experience with interferometry. He calls the concept of SPIDER “fundamentally sound,” but adds that it will require such extensive optical plumbing on a photonic scale that the sheer complexity “would scare a lot of folks away.” If the SPIDER team makes it work, great. “But it is a lot of work to save a little space.”

Peter Tuthill, an astronomer at the University of Sydney in Australia, leads one of the world’s busiest interferometry groups. His team has augmented such large conventional ground-based telescopes as the Keck Observatory in Hawaii with auxiliary interferometers. His group also designed an interferometer to be included on the James Webb Space Telescope, planned successor to the Hubble. After looking over the SPIDER proposal, he declared by e-mail, “I think the argument made that this can be somehow cheaper, simpler, lower mass and higher performance than conventional optics appears not to pass the laugh test.”

The extremely large number of waveguides in the SPIDER design, he added, would leave the signal strength per waveguide too feeble — hence vulnerable to swamping by noise in the system. “In short, I don’t think (the SPIDER team members) are waiting for technology to enable their platform. I think they are waiting for a miracle that defies physics.”

Duncan just smiles when he hears Tuthill’s opinion. Even if technical difficulties delay or quash this initial SPIDER project, he is confident somebody will step in and surmount any barriers. “It will happen,” he says.

Like an interplanetary parfait, the dwarf planet Ceres appears to have layers.

A pliable outer shell of minerals, ices and salts encapsulates a core of solid rock, a new study suggests. This first peek inside Ceres — courtesy of NASA’s Dawn spacecraft — can help researchers explain some mysteries on the surface and provide insight into the many ways planets and asteroids might be assembled. Ryan Park, a planetary scientist at the Jet Propulsion Laboratory in Pasadena, Calif., and colleagues report the findings online August 3 in Nature.
“Before we got to Ceres, we didn’t know what the interior looked like,” Park says. “Its evolution is more complex than what we envisioned.”

Ceres is the largest body in the asteroid belt, the field of rocks that lies between the orbits of Mars and Jupiter. The Dawn spacecraft has been orbiting Ceres since March 6, 2015, its second stop after spending 14 months at the asteroid Vesta (SN: 4/4/15, p. 9). As Dawn loops around Ceres, slight changes in the speed of the spacecraft — deviations of less than 0.1 millimeters per second — reveal the dwarf planet’s gravity field. By combining these measurements with images that show the overall shape of Ceres, the researchers deduced how mass is spread out inside. The core has a density similar to some meteorites; the shell (roughly 70 to 190 kilometers thick) is about two-thirds as dense.
Mountains on Ceres appear to float on a deformable layer of minerals and volatile elements that easily evaporate, Park and collaborators report. If Ceres were completely solid, then gravity over a mountain would be stronger than the surrounding terrain because of the increased mass. But gravity on Ceres doesn’t vary with topography, the researchers find. This suggests that mountains and hills displace mass beneath the surface, “like how a boat floats on water,” says Park. To keep the underlying layer slightly flexible, the temperature inside Ceres must be warm relative to the surface. That heat could come from radioactive decay or be left over from when Ceres assembled itself over 4 billion years ago.
This segregation of material — a solid core topped with a malleable crust — can help researchers learn about the environment in which Ceres formed, says Simone Marchi, a planetary scientist at the Southwest Research Institute in Boulder, Colo. Densities within these layers can lead to estimates of how much ice and radioactive material lies buried beneath the surface, he says — abundances which depend on how far from the sun Ceres was born.

Understanding the internal structure could also be key to solving a mystery: No craters on Ceres are wider than about 280 kilometers, which is odd given what researchers know about the population of rocks that should have slammed into it (SN: 9/5/15, p. 8). Something probably eroded those craters, though it’s not yet clear what. Marchi speculates that the erosion has something to do with Ceres’ internal evolution and composition.

Aside from getting an idea of how Ceres is put together, the findings can be applied to other worlds both in our solar system and around other stars, says Peter Thomas, a planetary scientist at Cornell University. Insight from Ceres adds “a whole new dimension of things that may not have been imagined before,” he says. “How many different kinds of objects — planets, dwarf planets, asteroids — can you get?”

Primates may have some high-flying relatives. Colugos, small mammals that glide from treetop to treetop in forests throughout Southeast Asia, have an evolutionary history that’s long been debated. Their teeth look similar to tree shrews’ teeth, while other skull and genetic features resemble those of primates. (Past studies have even linked colugos to bats and other insect-eating mammals.)

In an effort to settle the debate, William Murphy, a geneticist at Texas A&M University in College Station, and colleagues have deciphered the genome of a male Sunda colugo (Galeopterus variegatus) from West Java, Indonesia. Comparing colugo DNA with 21 other mammal genomes, the team found that colugos are most closely related to primates, while tree shrews took different evolutionary paths to arrive at similar traits. There are also changes in genes related to vision and gliding that are unique to colugos, the researchers report August 10 in Science Advances.
Genetic data from colugos preserved in museums also show that the animals are more diverse than suspected. While only two species have been described in the wild, the team found at least seven separate genetic lineages, which may represent individual species.