Scienti c balloons 15–35 km IN FOCUS NEWS

30 , founded the Perlan Project Perlan 2 temperature, humidity and wind, which the 27.4 km (target) with the aim of creating a that could surf glider is uniquely placed to measure. Airbus

SR-71 Blackbird NATURE these waves up to the . And in 2006, (military jet) says that many of the weather phenomena he and the US adventurer proved 25.9 km Perlan 2 will encounter will provide useful

the concept with their record-breaking flight s information for it and other makers e v a on Perlan 1, a modified conventional glider. that are contemplating operating aeroplanes JACKMAN/ PAUL w

n But Fossett’s death the following year in a i at higher altitudes. a t light-aircraft accident set the project back until n Once Perlan is fully tested, says Austin, she u July 2014, when European aerospace group o hopes to get funding to use the glider as a long- 20 M Airbus became a major sponsor and contrib- term scientific platform that would examine uted its research expertise. The Perlan 2 craft Gulfstream GV how hourly, seasonal or even decadal changes made its maiden flight last year in Oregon, and Perlan 1 (research jet) in the stratosphere affect weather and climate. 15.4 km 15.5 km in March surfed its first mountain waves above A drone that could carry more instru- the Sierra Nevada range in California. ments is a future possibility — but for now, Its next flights will be over on Stratosphere a piloted craft is preferable and simpler, says the eastern and southern fringes of the Andes Ed Warnock, the project’s chief executive. range in Argentina. There, during the South Commercial airliner Machines cannot yet match the best human 10–12 km Pole’s winter, a fast-moving, high-altitude jet 10 pilots when it comes to climbing waves in such stream called the polar-night jet extends from demanding flight conditions, he says. the troposphere into the upper atmospheric Perlan’s backers hope that it can surpass layers — helping the Andes mountain waves Andes mountain range 27,000 metres in 2017 — and, ultimately, they (and the glider) to reach the stratosphere (see 7 km intend another version of the glider to fly ‘Science on a glider’). higher than 30,000 metres, where the air den- Besides its atmospheric chemistry, Perlan 2 sity is almost identical to that on Mars’s surface. will carry instruments to study turbulence in That might provide insight into how winged stratospheric mountain waves, and to explore aircraft could fly on the red planet. the microphysics of interactions between 0 km For now, engineers and scientists alike are mountain waves and polar meteorology, just hoping to see the glider soar into the which ultimately affect weather variability. SCIENCE ON A GLIDER stratosphere above the Andes and take data. The Perlan glider aims to y higher than any Information on how mountain waves break other piloted aircraft, and to conduct unique “Everything in the aircraft is experimental. It’s in the stratosphere is “extremely limited”, says stratospheric research. a very difficult mission to do right, and to do it Gong, and requires detailed, fine-scale data on safely is not easy,” Austin says. ■

BIOMEDICINE US to lift ban on funding for human-animal hybrids Researchers in the United States will soon be able to resume chimaera-based projects.

BY SARA REARDON applications that fall into a grey area would University of Rochester in New York, says that undergo a panel review. the 2015 ban was overkill and is relieved that ince September 2015, researchers have The panel will pay particular attention to it will be lifted. been banned from receiving funding projects involving primates, mammals at very But Ali Brivanlou, a developmental biolo- from the US National Institutes of Health early developmental stages or those in which gist at Rockefeller University in New York City, S(NIH) for adding human stem cells to animal human cells could affect an animal’s brain. Past says that the new rules should focus on limit- embryos, creating blends called chimaeras. But a certain point, rodent embryos with human ing the percentage of the animal that becomes an NIH proposal released on 4 August lifts that cells that could affect brain development are human instead of restricting the timing of moratorium, with certain exceptions. It also exempt from panel review, because there is modifications. sets up a panel to review the ethics and over- little chance they would become human-like, Bioethicist Françoise Baylis, at Dalhousie sight of grant applications. says Carrie Wolinetz, NIH’s associate director University in Halifax, Canada, worries that The proposal shortens the window during for science policy in Washington DC. there are no clear guidelines on how chimae- which human cells can be introduced into Currently, researchers use chimaeras to ras should be treated when used as research non-human primate embryos, disallowing it study early embryonic development and subjects. before the central nervous system begins to human diseases. But a major goal is to engineer These are the kinds of questions that the form. This limits the number of human cells animals to grow human organs that could then oversight panel will discuss when reviewing incorporated into a chimaera’s brain. It also be transplanted into patients. grant applications, says Wolinetz. The NIH prohibits breeding animals containing human Unlike in the United States, it is illegal to proposal is open for public comment for cells, preventing growth of a chimaeric embryo perform such research without approval in the 30 days, after which the agency will issue a final in a non-human womb or the birth of an ani- United Kingdom, even with private funding. rule. Wolinetz hopes that it will be ready for the mal more humanized than its parents. Grant Steven Goldman, a neuroscientist at the January 2017 grant cycle. ■

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