Scanning the skies for near-earth asteroids might be the best first step for getting humans to Mars.
planetary scientist Richard Binzel argues that NASA should abandon the AsteroidRedirect Mission, the space agency’s plan to snag a space rock and jockey it into lunar orbit for astronauts to explore. Instead, NASA should beef up its telescope surveys to search for asteroids that come closer to home. At least one whizzes between the Earth and the moon every week, Binzel writes.
Sending humans out to these nearby asteroids would save scientists the trouble of wrangling a far-outspace rock, and it would giveastronauts a smorgasbord ofdifferent stepping stones to Mars, he notes.
Itty-bitty seeds of human stomachs can now bud in plastic dishes.
By bathing stem cells in a brew of growth-boosting chemicals, scientists have kick-started the constructionof crude organs about as bigas the head of a pin. These primitive balls of gastric tissue — the first to be cooked up in the lab — resemble the stomachs of developing fetuses. The lab-grown bellies represent the latest in a line of do-it-yourself organlike cell clumps, including livers, brains and guts
Three years after figuring outhow to transform stem cells into human intestinal tissue, and more recently, how to make that tissue grow in mice (SN Online: 10/19/14), developmental biologist James Wells of Cincinnati Children’s Hospital Medical Center and colleagues have monkeyed with their method to make 3-D stomachlike organs.
Like human stomachs, the lab-grown globs contain both mucus-making and hormone-pumping cells. Thetissue also mimics a stomach’s response to infection withHelicobacter pylori. The ulcer-causing bacteria cue the globs to switch on the same molecular signals that real stomach cells use, Wells andhis team reportOctober 29 inNature.
The mini stomachs hand researchers a new tool for studying gastric human disease, including cancer, the researchers suggest.
A tiny quail and a huge ostrich would seem to have little in common given their 500-fold difference in size. But when faced with an obstacle in their path, the birds tackle it in the same way, scientistsreportOctober 29 in theJournal of Experimental Biology.Aleksandra Birn-Jeffery of the Royal Veterinary College in Hatfield, England, and colleagues wanted to know how running birds negotiate a step. How two-legged creatures navigate obstaclescan be helpful for inventors hoping to create two-legged robots, but it seems that humans may not be the best models. Though our ancestors started walking uprightmillions of years ago, birds have been doing it for far longer — bipedal locomotion can be traced back 230 million years totheropoddinosaurs.So the researchers brought five species of birds into the lab: quail, pheasant, guinea fowl, North American turkey and ostrich. Because ostriches are capable of killing people (a common trait among manylarge flightless birds), Birn-Jeffery hand-raised the birds for twoyears so they could be safelyhandled. Members of the other species had their wings clipped so that they wouldn’t fly away.
The scientists presented each bird with a step sized appropriately to the bird’s height. Each bird ran over theobstacle, taking some practice runs so they could optimize their strategy. Then the researchers filmed the birds on their runs and measured the force of their steps.All the birds tackled the step in a similar way — in three steps, with an initial vault onto the step and slightly crouching while on top of it — regardless of size. This was surprising because the large ostrich runs differently than the smaller birds. The ostrich uses straighter legs to minimize stress on muscles and bones, while the smaller species tend to crouch, which allows for smooth body motion over uneven terrain. But when faced with a step, all the birds used a strategy that coupled energy efficiency with leg safety.“In the wild, injuries can result in predation, and food energy resources are often limited, thus, injury avoidance and economy are likely to be important factors in fitness,” the researchers note.The motion isn’t always smooth and sleek, though. The birds avoid falling and injuring themselves, but theirupper bodies may bounce around.The similarities between species may break down, however, with obstacles of a different size or type, Birn-Jeffery says. “A large bird, such as an ostrich, would not be able to successfully negotiate an 80-percent-leg-length obstacle using this strategy,”she says. “They would more than likely have to slow down before encountering the obstacle, something which none of our birds in the current study did.” A quail, though, might not haveto change its strategy to tackle a higher height.Coauthor Monica Daley, also at the Royal Veterinary College, is currently investigating whether the birds’ strategies change withother types of terrain. The research may help scientistscreate stable, running robots.Bipedal, ground-running birds come in a variety of sizes, from tiny quail to hugeostriches. But when presented with a short step, they all tackle the obstacle ina similar way: an initial vault up, slightly crouching on top and a third step back down to the ground.
A new frog species, discovered in New York City six years ago, has been found in many spots along the East Coast, from Connecticut to North Carolina.The Atlantic Coast leopard frog (Rana kauffeldi) wasfirstidentified on Staten Island when ecologists realized that its call was distinct fromthat of a lookalike, the southern leopard frog (Rana sphenocephala). The Atlantic Coast speciescroaks in a single burst of sound, while the southern leopard frog calls with multiple pulses.Researchers have now collected recordings of calls and tissue samples from leopard frogs along the East Coast to define the range of the new species. They found the Atlantic Coast leopard frog in coastal freshwater wetlands and low-lying river floodplains along a wide swath of the coast. The new frog’s rangeis described October 29 inPLOS ONE.“We can still find new species not only in the rainforest or in remote areas of the world, but in places that are very familiar,” says coauthor Jeremy Feinberg, an ecologist at Rutgers University in New Brunswick,N.J. “Your backyard might just have a surprise.”
NASA scientists have applied new super-black carbon-nanotube coating to a 3-D component critical for suppressing stray light in a new solar coronagraph.
An emerging super-black nanotechnology that is to be tested for the first time this fall on the International Space Station will be applied to a complex, 3-D component critical for suppressing stray light in a new, smaller, less-expensive solar coronagraph designed to ultimately fly on the orbiting outpost or as a hosted payload on a commercial satellite.
The super-black carbon-nanotube coating, whose development is six years in the making, is a thin, highly uniform coating of multi-walled nanotubes made of pure carbon about 10,000 times thinner than a strand of human hair. Recently delivered to the International Space Station for testing, the coating is considered especially promising as a technology to reduce stray light, which can overwhelm faint signals that sensitive detectors are supposed to retrieve.
While the coating undergoes testing to determine its robustness in space, a team at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, will apply the carbon-nanotube coating to a complex, cylindrically shaped baffle — a component that helps reduce stray light in telescopes.
Goddard optical engineer Qian Gong designed the baffle for a compact solar coronagraph that Principal Investigator Nat Gopalswamy is now developing. The goal is build a solar coronagraph that could deploy on the International Space Station or as a hosted payload on a commercial satellite — a much-needed capability that could guarantee the continuation of important space weather-related measurements.
The effort will help determine whether the carbon nanotubes are as effective as black paint, the current state-of-the-art technology, for absorbing stray light in complex space instruments and components.
Preventing errant light is an especially tricky challenge for Gopalswamy’s team. “We have to have the right optical system and the best baffles going,” said Doug Rabin, a Goddard heliophysicist who studies diffraction and stray light in coronagraphs.
The new compact coronagraph — designed to reduce the mass, volume, and cost of traditional coronagraphs by about 50 percent — will use a single set of lenses, rather than a conventional three-stage system, to image the solar corona, and more particularly, coronal mass ejections (CMEs). These powerful bursts of solar material erupt and hurdle across the solar system, sometimes colliding with Earth’s protective magnetosphere and posing significant hazards to spacecraft and astronauts.
“Compact coronagraphs make greater demands on controlling stray light and diffraction,” Rabin explained, adding that the corona is a million times fainter than the sun’s photosphere. Coating the baffle or occulter with the carbon-nanotube material should improve the component’s overall performance by preventing stray light from reaching the focal plane and contaminating measurements.
The project is well timed and much needed, Rabin added.
Currently, the heliophysics community receives coronagraphic measurements from the Solar and Heliospheric Observatory (SOHO) and the Solar Terrestrial Relations Observatory (STEREO).
“SOHO, which we launched in 1995, is one of our Great Observatories,” Rabin said. “But it won’t last forever.” Although somewhat newer, STEREO has operated in space since 2006. “If one of these systems fails, it will affect a lot of people inside and outside NASA, who study the sun and forecast space weather. Right now, we have no scheduled mission that will carry a solar coronagraph. We would like to get a compact coronagraph up there as soon as possible,” Rabin added.
Ground-based laboratory testing indicates it could be a good fit. Testing has proven that the coating absorbs 99.5 percent of the light in the ultraviolet and visible and 99.8 percent in the longer infrared bands due to the fact that the carbon atoms occupying the tiny nested tubes absorb the light and prevent it from reflecting off surfaces, said Goddard optics engineer John Hagopian, who is leading the technology’s advancement. Because only a tiny fraction of light reflects off the coating, the human eye and sensitive detectors see the material as black — in this case, extremely black.
“We’ve made great progress on the coating,” Hagopian said. “The fact the coatings have survived the trip to the space station already has raised the maturity of the technology to a level that qualifies them for flight use. In many ways the external exposure of the samples on the space station subjects them to a much harsher environment than components will ever see inside of an instrument.”
Given the need for a compact solar coronagraph, Hagopian said he’s especially excited about working with the instrument team. “This is an important instrument-development effort, and, of course, one that could showcase the effectiveness of our technology on 3-D parts,” he said, adding that the lion’s share of his work so far has concentrated on 2-D applications.
By teaming with Goddard technologist Vivek Dwivedi, Hagopian believes the baffle project now is within reach. Dwivedi is advancing a technique called atomic layer deposition (ALD) that lays down a catalyst layer necessary for carbon-nanotube growth on complex, 3-D parts. “Previous ALD chambers could only hold objects a few millimeters high, while the chamber Vivek has developed for us can accommodate objects 20 times bigger; a necessary step for baffles of this type,” Hagopian said.
Other NASA researchers have flown carbon nanotubes on the space station, but their samples were designed for structural applications, not stray-light suppression — a completely different use requiring that the material demonstrate greater absorption properties, Hagopian said.
“We have extreme stray light requirements. Let’s see how this turns out,” Rabin said.
