One of the Best Explanations For Why We Haven't Found Alien Life

from Gizmodo

So far, the only examples of sentient life we’ve found are right here on our own planet. It’s not for lack of trying, though—we’ve sent out spacecraft deep into our solar system and, so far, still remain alone. What if the problem isn’t where we are looking, though, but when?

A forthcoming study in Journal of Cosmology and Astroparticle looks at the possibility that life as we know it may not require a star similar to our sun but could emerge on planets orbiting much smaller, weaker stars. If we do allow for the possibility of life around non-sunlike stars, then it turns out that the universe is likely to be much more habitable in the distant future than it is today.

“It’s natural for us to think that we are the most common form of life, simply because that’s the only one that we know of,” lead author of the paper, Harvard University’s Avi Loeb, told Gizmodo. “Therefore, people assumed that being next to star like the sun was the most likely place for life to emerge.”

If you throw out the assumption that we need a sun-like star, though, then there’s a whole new class of stars—smaller and less powerful than the sun, but far more common—that suddenly start to look like good candidates. They’re called low mass stars.

Although these stars throw out less light and heat than our powerful sun, they still emit enough to create potentially habitable zones that could support liquid water on close-orbiting rocky planets. Not only are these types of stars more common in the universe than sun-like stars, but they also have much considerably longer lifespans of more than 1,000 times that of the sun.

Using this information, Loeb calculated that it was much more likely for life to have emerged in the distant future around one of those low mass stars than to have emerged in our time on a sun-orbiting planet like Earth.

“If you allow low mass stars to have life, just like we find here on Earth, then the probability of life emerging in the future 10 trillion years from now is one thousand times bigger to find life,” noted Loeb.

And yet, we are not orbiting a low mass star, trillions of years in the future. We are here and now, orbiting our Sun—and this is the only place we’ve ever found sentient life. That suggests an intriguing explanation. Perhaps we are simply searching way too soon.

In other words, we may be alone in the universe right now. But that’s only because we showed up long before life really started to get going. If this hypothesis is the correct one, then the real explosion of life in the universe hasn’t yet happened—and likely won’t happen for trillions of years after us.

There’s also a second, alternate explanation that would account for all the facts. Perhaps there’s something about low mass stars which, even in zones that are technically habitable, suppresses life from ever forming.

“We still keep the notion that, perhaps, we are at the center of the biological universe, that we are really the only ones or special in that regard, or in terms of intelligence,” Loeb said. “If it turns out that we are rare and early on in the game then that would be really surprising to me because, so far, whenever we look we have found that we are not special and we are not the center of the universe.”

Figuring out which of these two possibilities are correct hinges on the question of whether low mass stars can indeed support life. We won’t necessarily have to wait several trillions of years to find out, though. Instead, Loeb suggests that the answers could be found in the next decade or so.

By sampling the atmospheres of planets around nearby low mass stars, researchers can search for biomarkers that would suggest whether these planets are capable of supporting life. If they keep finding atmospheres devoid of signs that they are capable of supporting life, then it’s likely that something about these low mass stars—perhaps their frequent solar flares or some other attribute—renders the planets orbiting them sterile.

If, however, they find that these planets do appear able to support life then it may be that the lack of other life in the universe is simply because we showed up too soon to see any of it.

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In a Breathtaking First, NASA’s Voyager 1 Exits the Solar System

from The New York Times:



By BROOKS BARNES

PASADENA, Calif. — By today’s standards, the spacecraft’s technology is laughable: it carries an 8-track tape recorder and computers with one-240,000th the memory of a low-end iPhone. When it left Earth 36 years ago, it was designed as a four-year mission to Saturn, and everything after that was gravy.

But Voyager 1 has become — thrillingly — the Little Spacecraft That Could. On Thursday, scientists declared that it had become the first probe to exit the solar system, a breathtaking achievement that NASA could only fantasize about back when Voyager was launched in 1977, the same year “Star Wars” was released.

“I don’t know if it’s in the same league as landing on the moon, but it’s right up there — ‘Star Trek’ stuff, for sure,” said Donald A. Gurnett, a physics professor at the University of Iowa and the co-author of a paper published Thursday in the journal Science about Voyager’s feat. “I mean, consider the distance. It’s hard even for scientists to comprehend.”

Even among planetary scientists, who tend to dream large, the idea that something they built could travel beyond the Sun’s empire and keep grinding away is impressive. Plenty of telescopes gaze at the far parts of the Milky Way, but Voyager 1 can now touch and feel the cold, unexplored region in between the stars and send back detailed dispatches about conditions there. It takes 17 hours and 22 minutes for Voyager’s signals to reach NASA’s Jet Propulsion Laboratory here.



“This is historic stuff, a bit like the first exploration of Earth, and we had to look at the data very, very carefully,” said Edward C. Stone, 77, NASA’s top Voyager expert, who has been working on the project since 1972. He said he was excited about what comes next. “It’s now the start of a whole new mission,” he said.

The lonely probe, which is 11.7 billion miles from Earth and hurtling away at 38,000 miles per hour, has long been on the cusp, treading a boundary between the bubble of hot, energetic particles around the solar system and the dark region beyond. There, in interstellar space, the plasma, or ionized gas, is noticeably denser.

Dr. Gurnett and his team have spent the past few months analyzing their data, trying to nail down whether what they were seeing was solar plasma or the plasma of interstellar space. Now they are certain it was the latter, and have even pinpointed a date for the crossing: Aug. 25, 2012.

At a news conference on Thursday, NASA scientists were a bit vague about what they hope to get from Voyager 1 from now on. The answer, to some extent, depends on what instruments continue to function as the power supply dwindles. Dr. Stone expects Voyager 1 to keep sending back data — with a 23-watt transmitter, about the equivalent of a refrigerator light bulb — until roughly 2025.

One hope is that Voyager 1’s position will allow scientists to more accurately study galactic cosmic rays, which are high-energy particles that originate outside the solar system. They would use the information to make judgments about what interstellar space is like at even greater distances from Earth.

In its heyday, Voyager 1 pumped out never-before-seen images of Jupiter and Saturn. But it stopped sending home pictures in 1990, to conserve energy and because there was no longer much to see. A companion spacecraft, Voyager 2, also launched in 1977, has stopped sending back images as well. Voyager 2 is moving in a different direction but is also expected to exit the solar system.

Eventually, NASA said, the Voyagers will pass other stars, coasting and drifting and being pulled by gravity. The next big encounter for Voyager 1, in around 40,000 years, is expected to be a dwarf star dispassionately known as AC+793888 in the constellation of Camelopardalis.

But already, Voyager 1 has achieved what Dr. Gurnett called “the holy grail of heliosphere research.”

Voyager 1 left the solar system the same month that Curiosity, NASA’s state-of-the-art rover, landed on Mars and started sending home gorgeous snapshots. Curiosity’s exploration team, some 400 strong, promptly dazzled the world by driving the $2.5 billion robot across a patch of Martian terrain, a feat that turned the Red Bull-chugging engineers and scientists of Building 264 of the Jet Propulsion Laboratory campus into rock stars. By comparison, the Voyager mission looked like a Betamax in the era of Bluetooth.

The 12-person Voyager staff was long ago moved from the Jet Propulsion Laboratory campus to cramped quarters down the street, next to a McDonald’s. In an interview last month at Voyager’s offices, Suzanne R. Dodd, the Voyager project manager, said that when she attended meetings in Building 264, she kept a low profile in deference to the Mars team.

“I try to stay out of the elevator and take the stairs,” Ms. Dodd said. “They’re doing important work there, and I’ll only slow them down.”

At 52, Ms. Dodd is a relative newcomer to Voyager, first working on the mission in 1984. Now she and her team seem poised to return to the spotlight.

As the solar system’s edge grew tantalizingly close, NASA asked the Voyager scientists to increase the amount of data collection. The problem: the 8-track data recorders from 1977 were not exactly bursting with extra space. Could Ms. Dodd even find anyone who specialized in that piece of technology and could coax it to record more?

“These younger engineers can write a lot of sloppy code, and it doesn’t matter, but here, with very limited capacity, you have to be extremely precise and have a real strategy,” she said.

She was able to find her man: Lawrence J. Zottarelli, 77, a retired NASA engineer. He came up with a solution. But would it work?

Mr. Zottarelli waited at Voyager mission control one afternoon last month to find out. The first of the newly programmed data dumps was set to come down. Ms. Dodd, Dr. Stone and Mr. Zottarelli watched two old Sun Microsystems computers like children watching for a chick to peck through an egg. “Nine, eight, seven,” Dr. Stone counted down.

“Everything’s fine,” said Mr. Zottarelli, flashing a thumbs up. “You’re on your own now.”

The relief was written all over Ms. Dodd’s face. “It’s not easy flying an old spacecraft,” she said.

Her eyes moved to Dr. Stone, who was peering at a computer through his trifocals.

“There are lots of old missions,” he responded with a sly smile. “But not many are doing exciting new things.”



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