Mysterious radio signal spotted in Milky Way for first time
BY MICHAEL GRESHKO - November 4 2020
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Three new studies trace the burst to a bizarre "magnetic star" — and help solve a major astronomical puzzle.
IN A THOUSANDTH of a second on April 28, a powerful burst of radio waves washed over Earth, lighting up radio telescopes in North America. Now, astronomers have tracked down the source of this strange signal — and the results could reveal the long-sought cause of some of the most mysterious cosmic signals ever recorded.
In three studies published today in the journal Nature, an international group of scientists identified the blast as a fast radio burst, an extremely intense flash of radio waves that lasts no more than a few milliseconds. Telescopes have picked up such bursts before, but always from outside our galaxy. Researchers have wondered for years what could cause these ephemeral but powerful blasts, with speculation ranging from exploding stars to alien technologies.
Now we know that at least one source is likely an exotic stellar object called a magnetar: a type of young neutron star left over after a large star explodes that has an extremely powerful magnetic field.
“When I looked at the data for the first time, I froze and was basically paralyzed with excitement,” Caltech graduate student Christopher Bochenek, a lead author of one of the studies, said in a Monday press briefing.
The new signal is the first fast radio burst pinned down to a specific source, providing a unique opportunity to finally study one of these cosmic flashes in detail. “This gives us a whole new handle on [fast radio burst] progenitor theories,” University of Cape Town astrophysicist Amanda Weltman, who wasn’t involved with the studies, says in an email.
Searching for bursts in the darkness
Discovered in 2007, fast radio bursts are extremely difficult to study because they’re over so quickly. In the early days, some scientists were skeptical that they were genuinely from space and not a misidentified signal from a source on Earth, such as microwave ovens.
By 2013, the discovery of four more bursts confirmed their cosmic origins — and deepened their mystery. Three years later, astronomers announced the discovery of a repeating source, which they were able to trace back to a galaxy more than 2.6 billion light-years from Earth. Now, astronomers have found more than a hundred fast radio bursts — roughly 20 of which are repeating.
Source: National Geographic - Photograph by Bojun Wang, Jinchen Jiang with post-processing by Qisheng CUi
How many alien civilizations are out there? A new galactic survey holds a clue
BY NADIA DRAKE - NOVEMBER 2 2020
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Here’s a good sign for alien hunters: More than 300 million worlds with similar conditions to Earth are scattered throughout the Milky Way galaxy. A new analysis concludes that roughly half of the galaxy’s sunlike stars host rocky worlds in habitable zones where liquid water could pool or flow over the planets’ surfaces.
“This is the science result we’ve all been waiting for,” says Natalie Batalha, an astronomer with the University of California, Santa Cruz, who worked on the new study.
The finding, which has been accepted for publication in the Astronomical Journal, pins down a crucial number in the Drake Equation. Devised by my father Frank Drake in 1961, the equation sets up a framework for calculating the number of detectable civilizations in the Milky Way. Now the first few variables in the formula — including the rate of sunlike star formation, the fraction of those stars with planets, and the number of habitable worlds per stellar system — are known.
The number of sunlike stars with worlds similar to Earth “could have been one in a thousand, or one in a million — nobody really knew,” says Seth Shostak, an astronomer at the Search for Extraterrestrial Intelligence (SETI) Institute who was not involved with the new study.
“Every other sunlike star is likely, on average, to have a potentially habitable planet.”
Astronomers estimated the number of these planets using data from NASA’s planet-hunting Kepler spacecraft. For nine years, Kepler stared at the stars and watched for the brief twinkles produced when orbiting planets blot out a portion of their star’s light. By the end of its mission in 2018, Kepler had spotted some 2,800 exoplanets — many of them nothing like the worlds orbiting our sun.
But Kepler’s primary goal was always to determine how common planets like Earth are. The calculation required help from the European Space Agency’s Gaia spacecraft, which monitors stars across the galaxy. With Gaia’s observations in hand, scientists were finally able to determine that the Milky Way is populated by hundreds of millions of Earth-size planets orbiting sunlike stars — and that the nearest one is probably within 20 light-years of the solar system.
Source: National Geographic - Illustration by Nasa Ames / JPL-CALTECH / T. Pyle
How the Space Station Became a Base to Launch Humanity’s Future
BY KENNETH CHANG - NOVEMBER 2 2020
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Once derided as a poster child for government waste, the outpost in orbit is now seen as a linchpin for future economic activity in space.
For the International Space Station, Leroy Chiao was, in a sense, there before the beginning.
In October 2000, he was one of seven astronauts on the space shuttle Discovery, which brought pieces of the nascent space station to orbit. Construction had begun a couple of years earlier. But no one was living there yet.
Much of the work on Dr. Chiao’s flight was done outside the space station, during spacewalks. But the astronauts also got to go inside briefly.
“It had that new-car smell,” Dr. Chiao recalled.
It was a runt of a space station then. The habitable portion consisted of just three modules, not the 16 orbiting today. But it was ready for people to move in.
Discovery undocked on Oct. 20 and returned to Earth. Eleven days later, three astronauts — William Shepherd of NASA and two Russians, Sergei Krikalev and Yuri Gidzenko — blasted off in a Russian Soyuz rocket from the Baikonur Cosmodrome in Kazakhstan.
On Nov. 2, 2000, they docked at the space station and began their four-and-a-half-month stay in orbit.
Humans have been living off the planet ever since.
Source: NYTimes - Gerald P. Carr, commander of the Skylab 4 mission in 1973-74, demonstrated zero gravity in the dome area of Skylab’s orbital workshop.Credit...NASA
Monday is the 20th anniversary of continuous occupation of the International Space Station. The project was pitched as post-Cold War space cooperation between the United States and Russia, although for many its cost — well above $100 billion — made it a poster child of inefficient government megaprojects.
"If that’s one of your main objectives of the program, I think it has been a great success.”
In the past decade, however, the station has, somewhat unexpectedly, turned into the linchpin for spurring capitalism in space, potentially leading to new industries and the possibility that more people will head to orbit.
Research conducted on the space station has yet to discover a cure for cancer or osteoporosis. And it has not generated a technological breakthrough that would transform life on Earth. But it has given NASA and other space agencies the knowledge and experience of how to build complex machinery in space, and insight into how microgravity affects the human body.
“The whole thing is an experiment of, Can humans live in space for long periods of time, operate in this challenging environment, and do it safely, do it successfully?” said Scott Kelly, one of the space station’s most prominent residents, who spent nearly a year in orbit, beginning in March 2015. “If that’s one of your main objectives of the program, I think it has been a great success.”