【Native Speaker每日综合训练——37系列】【37-11】 科技

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Part I: Speaker

Dark Matter Shell Saved Wannabe Galaxy
A failed dwarf galaxy called the Smith Cloud apparently survived an ancient collision with the Milky Way because of a protective dark matter cloak. Clara Moskowitz reports   

Dark matter is that mysterious stuff that apparently accounts for some quarter of the mass and energy in the universe. And for one small wannabe-galaxy, dark matter may have been a lifesaver.

It’s called the Smith Cloud. Astronomers think it’s a failed dwarf galaxy that lacked the requisite mass to produce stars. Many millions of years ago the cloud seems to have collided with the Milky Way and passed through the disk of our galaxy. A new computer simulation finds that the cloud should have been ripped to shreds. That it survived is evidence that it’s protected—by a shell of dark matter.

The report will appear in the journal Monthly Notices of the Royal Astronomical Society. [Matthew Nichols et al, The Smith Cloud and its dark matter halo: Survival of a Galactic disc passage]

That dark matter shell could have insulated the Smith Cloud from the Milky Way’s gravitational forces, which otherwise should have torn Smith apart.

As if its first fender-bender with the Milky Way wasn’t enough, the Smith Cloud is coming back for more. It’s on course to slam into our galaxy again—in about 30 million years. Perhaps future astronomers will note whether its dark matter shroud once again saves the cloud.

—Clara Moskowitz

Source: Scientificamerican
http://www.scientificamerican.com/podcast/episode/dark-matter-shell-saved-wannabe-galaxy/


[Rephrase 1, 1:18]

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Part II: Speed

Rocky World Is 17 Times as Massive as Earth
BY Sid Perkins | 02 June 2014

[Time 2]

Most massive alien worlds are gas giants like Jupiter. But now, astronomers say they’ve found a new type of exoplanet: a rocky world much larger than Earth that may boast only a thin sheath of an atmosphere. The orb in question (in the foreground of artist’s concept), dubbed Kepler-10c, circles its 11-billion-year-old, sunlike star once every 45 days. Previously estimated to have a diameter about 2.3 times that of Earth (giving it a volume slightly more than 12 times our planet’s), new observations with ground-based sensors suggest that Kepler-10c is 17 times as hefty as Earth, the researchers report today in Boston at a meeting of the American Astronomical Society and in a forthcoming issue of The Astrophysical Journal. Those figures for mass and volume—which suggest a dense, rocky composition and seemingly discount a large, thick atmosphere—peg the planet as the first rocky “mega-Earth” to be found. Kepler-10c is surprising, the researchers say: Previously, astronomers surmised that any planet that massive would have gravitationally slurped up gases in its neighborhood as it formed, eventually growing to become a gas giant like those in the outer reaches of our solar system. The existence of large rocky worlds like Kepler-10c may boost the chances of potentially habitable worlds throughout the cosmos, the researchers contend.

[216 words]
Source: science
http://news.sciencemag.org/space/2014/06/rocky-world-17-times-massive-earth


Tests of Embryonic Stem Cell Treatment Back on Track
BY Kelly Servick | 30 May 2014

[Time 3]

A potential treatment for spinal cord injury that made headlines in 2010 as the first human embryonic stem cell therapy to be tested in humans is pushing ahead after a stalled clinical trial and a change of ownership. Asterias Biotherapeutics announced the results of an initial safety study of the therapy earlier this month, and yesterday the company won $14.3 million from the California Institute for Regenerative Medicine (CIRM) for the next round of trials.

CIRM had given $25 million to Menlo Park, California–based Geron, which developed the cells, to test the treatment, which uses neuronal cells derived from embryonic stem cells intended to restore function to spinal cord injury patients. But Geron halted the trial a year later to focus on anticancer therapies, fueling concerns that the treatment might not be as promising as hoped.

Asterias took over the project in 2013, and last week the company’s president of R&D, Jane Lebkowski, presented results from the first trial at the annual meeting of the American Society of Gene & Cell Therapy in Washington, D.C. The five patients with spinal cord injury who received a low dose of the treatment saw no adverse effects, she reported, and there was some evidence that further degeneration had been prevented at the injury site for four of them.  

The next study will focus on the upper part of the spine rather than the lower part. (Initial clinical trials for spinal cord injury often target the lower spine, as there is less risk of adverse consequences causing serious damage.) The company also plans a phase II trial to study the effect of higher dosages.

The therapy was one of two to gain approval yesterday as part of CIRM’s Strategic Partnership program. It provides funding to help propel a therapy through clinical trials on the condition that the recipient matches the investment.

[308 words]
Source: science
http://news.sciencemag.org/biology/2014/05/tests-embryonic-stem-cell-treatment-back-track


Wind may deflate search for habitable planets
Study suggests that stellar wind of M-dwarfs erodes atmosphere of planets in the habitable zone.
BY Ron Cowen| 02 June, 2014

[Time 4]

The hunt for habitable planets beyond the Solar System just became more difficult. A study posted today on the arXiv server suggests that the same factors that make planets near M-dwarf stars easy to probe for potential life also diminish the chances that life could actually exist on those planets.

Researchers have often cited the environs of M-dwarfs, a type of red dwarf star, as a relatively easy place to look for planets that might be habitable. The stars are the most common type in the Galaxy, and their small size and mass makes it easier to detect planets orbiting them and use starlight to probe the planets' atmospheres. M-dwarfs are cooler than the Sun, so their habitable zones — the region surrounding a star where water could exist as a liquid on a solid surface — are closer in than the Sun’s. Planets in that region therefore complete an orbit in less time than Earth takes to orbit the Sun, providing astronomers with more opportunities to study them.

But the habitable zones around M-dwarfs may be too close to the stars to sustain life, says astronomer Ofer Cohen of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, who announced the findings during a press briefing today at a meeting of the American Astronomical Society in Boston, Massachusetts. Just as the Sun blows a steady stream of charged particles — the solar wind — M-dwarfs generate their own wind. That wind can strip the protective atmosphere of a planet in the habitable zone, making it harder for life to gain a foothold, Cohen says. Only if the planet had a magnetic field stronger than that of Earth — powerful enough to deflect the stellar wind — could it hold on to its atmosphere, Cohen notes.

Earlier findings had led astronomers to question the viability of life on these planets. M-dwarf flares, for example, have been shown to erode the atmosphere of surrounding planets. “This is one more knock against habitable planets orbiting M-dwarf stars,” says geoscientist James Kasting of Pennsylvania State University in State College, who was not part of the study.

[347 words]

[Time 5]

Cohen and his team examined the influence of M-dwarfs on three planets that had been identified by NASA’s Kepler spacecraft and shown to reside in the habitable zones of their stars. Because key properties of the actual parent stars were not known, the team chose a dwarf star, Lacertae (EV Lac), which is a relatively young 300 million years old, as a stand-in. EV Lac’s luminosity and magnetic activity, which drives the stellar wind, is well characterized. The three candidate planets are much closer to their stars than Mercury is to the Sun.

The researchers found that the pressure from the stellar wind encountered by the planets would be 10–1,000 times stronger than that exerted on Earth.

However, M-dwarfs older than EV Lac are likely to have weaker winds, notes astrophysicist Edward Guinan of Villanova University in Pennsylvania. If so, a habitable-zone planet that survived for the first billion years with most of its atmosphere intact might still support life, he says.

Even if astronomers might be more likely to find life around stars resembling the Sun in size and mass, there is still a rationale, says Cohen, for missions like NASA’s Transiting Exoplanet Survey Satellite (TESS), which will study, among other things, planets in the habitable zone of M-dwarfs. Such observations will offer insight about the potential for life throughout the Galaxy, Cohen says. Astronomers have always been wary of how M-star activity might affect potentially habitable planets, says TESS scientist Sara Seager of the Massachusetts Institute of Technology in Cambridge. “Observers will always search for habitability without limits from theory,” says Seager. “What do we have to lose?”

[271 words]
Source: Nature
http://www.nature.com/news/wind-may-deflate-search-for-habitable-planets-1.15335


Outgoing congressman Rush Holt calls scientists to action
BY SAM LEMONICK | 3 June, 2014

[Time 6]

Rush Holt, central New Jersey’s “rocket scientist” representative, thinks Capitol Hill needs more scientists. He’s leaving Congress at the end of this year, but his eight terms in office have taught him that scientists need to help craft the nation’s laws now more than ever.

Holt joined Congress in 1999, and at one point was one of three physicists there. Fifteen years later he’ll leave the House with just one, Rep. Bill Foster of Illinois. A microbiologist, six engineers and about two dozen medical professionals also hold seats in the House or Senate.

“We need more scientists, more people with training as scientists, in Congress, on town councils, on county commissions until that golden age when everyone can think intelligently about science,” says Holt, a Ph.D. physicist and former assistant director of the Princeton Plasma Physics Laboratory. He says it’s not just about explicitly scientific issues like climate change and energy sources, either. Even voting laws can benefit when legislators think like scientists.

When electronic voting machines first appeared, for example, Holt and other scientists in Congress immediately saw what other politicians didn’t. Without a paper trail, results would not meet a basic standard of science: verifiability. Holt introduced a bill in 2008 to address the problem, and though it never passed nationally, states including California and Ohio did begin requiring paper records.

During his time in office, Holt got a $22 billion investment in new research into the 2009 stimulus package, helped write the College Cost Reduction Act and has been a vocal opponent of climate change denial. He has said that he’s leaving Congress not because of frustrations with its dysfunction, but because there are so many other things he can do — though he isn’t saying yet what his next steps will be.

“People interested in politics should learn science, and people involved in science should learn politics,” Holt says. For now, he puts the onus on scientists. “Scientists probably have greater responsibility than the average citizen to be involved in politics and policy,” he says, because they often have a deep understanding of complex topics. “That responsibility involves more than just voting.”

[357 words]
Source: sciencenews
https://www.sciencenews.org/article/outgoing-congressman-rush-holt-calls-scientists-action

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Part III: Obstacle

How to revive a satellite
BY G.F. | 30 MAY, 2014

[Paraphrase 7]

"WE JUST made contact. I need to talk to you in 30 minutes," says Keith Cowing, the editor of NASA Watch, an online publication. Just as Babbage called him, Mr Cowing received word from the Arecibo Observatory in Puerto Rico that his colleagues had made contact with a NASA satellite launched in August 1978. When your correspondent called back, Mr Cowing was irrepressible: the satellite had responded to commands and was now set into "coherent ranging mode", which should make it easier to talk to it. The group had captured the satellite.

This was no act of space piracy. Mr Cowing, Dennis Wingo of Skycorp and several other experts had received permission from NASA to take control of a satellite for which the space agency has no further purpose nor funding. With the help of nearly $160,000, raised through crowdfunding, the team hopes to start a new mission and release the raw data that emerge.

The International Solar-Environment Explorer (ISEE-3, see picture) completed its initial mission close to the sun, where it took measurements of solar properties, and was repurposed in 1983 to hunt comets as the International Cometary Explorer (ICE). During its second lease on life it intercepted comet Giacobini-Zinner in 1985 and then transited between the sun and Halley in 1986. This repurposing involved a series of intricate flybys of the Earth and the moon to slingshot the satellite into its comet-tracking trajectory. NASA shut down the mission in 1997, although occasionally checked in on the bird's status.

Before they turned off the light, Robert Farquhar, the mission's flight-dynamics manager, and his team used the satellite's propulsion system to set it on a course that 28 years after its final scientific measurements in 1986 would bring it close to Earth. The rendezvous is rapidly approaching. Dr Farquhar is now part of the ISEE-3 Reboot Project to re-establish contact. Mr Cowing says participants range in age from their 20s to their 80s, and include ex-NASA employees like himself as well as a current one who works on the project in his spare time.

Although the ISEE-3 was launched a year later than the Voyager 1 and 2 probes, its computers are much less powerful. The Voyagers had redundant sets of three separate computers and could store and execute programs, as well as radiological power sources. ISEE-3 can be triggered through radio commands to execute sequences of actions, but it cannot be put into an autonomous mode. Its batteries failed 20 years ago, and it is now entirely dependent on solar power.

It appears to have survived unscathed the long occupancy of the orbit in which it was parked. However, celestial mechanics have put the satellite about 250,000km off from where it was expected. Mr Cowing and his colleagues are slightly worried that it may bash into the moon or wander too close to Earth. The craft has antennas measuring 30 metres and extending in four directions, which at a certain altitude above Earth could cause problems. "It's a 360-foot spinning cookie cutter," says Mr Cowing.

That the reboot project has got that far is remarkable. Unable to receive a clear go-ahead or an outright no from NASA a few months ago, it set out to raise funds hoping that this might prompt the space agency to acquiesce. It is the first time in NASA's history that operational control has been handed over, and NASA made the announcement on May 23rd with due fanfare.

With the original software, computers or telecoms gear long gone, the team—with the help of some original mission members and others in and out of NASA who knew where to find the old manuals—recreated the equipment, including a software-defined radio system that allows talking and listening to the satellite. The Arecibo Observatory also provided help: it installed gear purchased by the Reboot Project and allowed it to use Arecibo's huge satellite dish free during downtimes. The team faced downpours of rain and even an earthquake with a magnitude of 5.8 while one of the volunteers worked near the dish.

Much remains to be determined. Mr Cowing and his colleagues have yet to decide whether the satellite is to explore more comets or to use it for other purposes. Just as both Voyager probes remain active and Voyager 1's ancient instruments in 2013 produced measurements that upended some long-held notions about interstellar magnetic fields, the group expects that its craft can provide data worth examining. The team will soon give up its big "ear" at Arecibo and decamp to Morehead State University in Kentucky: the initial capture and the repositioning allow the use of the smaller dish there.

This initial contact indicates that the satellite's computer and radios are functioning. The next steps are to determine more fully whether its control systems work as expected and test its instrumentation and propulsion. The team must fire its rockets by mid-June to reposition ISEE-3. The next big challenge will come when the satellite swings around the moon onto its shadowed side and is cut off from the sun. The craft will power down for the first time in many years, and the team hopes when it sees it again, it will wake up and resume communications. It has lasted this long, and the group hopes for many more years to come. "This thing has had a second act, and we're giving it its third," says Mr Cowing.

[900 words]
Source: economist
http://www.economist.com/blogs/babbage/2014/05/technoarchaeology