Humanity should be wary of seeking out contact with alien civilizations, Stephen Hawking has warned once again.
In 2010, the famed astrophysicist said that intelligent aliens may be rapacious marauders, roaming the cosmos in search of resources to plunder and planets to conquer and colonize. He reiterates that basic concern in “Stephen Hawking’s Favorite Places,” a new documentary streaming now on the CuriosityStream video service.
“One day, we might receive a signal from a planet like this,” Hawking says in the documentary, referring to a potentially habitable alien world known as Gliese 832c. “But we should be wary of answering back. Meeting an advanced civilization could be like Native Americans encountering Columbus. That didn’t turn out so well.”
For what it’s worth, some other astronomers believe Hawking’s caution is unwarranted. Any alien civilization advanced enough to come to Earth would surely already know of humans’ existence via the radio and TV signals that humanity has been sending out into space since 1900 or so, this line of thinking goes.
The alien musings are just a small part of “Stephen Hawking’s Favorite Places.” The 26-minute documentary shows the scientist zooming through the cosmos on a souped-up CGI spaceship called the “S.S. Hawking,” making five separate stops.
Hawking observes the Big Bang that created the universe, visits the monster black hole at the center of the Milky Way, journeys to Gliese 832c and tours Saturn in Earth’s own solar system. Then, he makes a final stop in Santa Barbara, California, which Hawking calls “my home away from home.”
“In 1974, Caltech [the California Institute of Technology] offered me a job in California,” the Englishman Hawking says in the documentary. “I jumped at the opportunity. In the sun with my young family, it was a world away from the gray skies of Cambridge, [England]. I’ve traveled the globe, but I’ve never found anywhere quite like this.”
You can watch a preview of “Stephen Hawking’s Favorite Places,” and learn how to subscribe to CuriosityStream, at the video service’s website: www.curiositystream.com.
The two objects straddle the dividing line between gas giants and odd “failed stars” known as brown dwarfs in terms of mass, researchers said. The newfound bodies are also similar to each other in size and age.
“They’re probably brother and sister,” Daniella Gagliuffi told Space.com. Gagliuffi, a graduate student at the University of California, San Diego, found the objects amid a cloud of stars about 65 light-years from Earth.
“It’s a little incestuous,” said Gagliuffi, who presented her research at the American Astronomical Society’s summer meeting in San Diego in June.
The pair lie within a dense cluster of stars that would normally be expected to strip objects away from one another. However, observations suggest that the two objects are so close that interactions with other stars would instead push them closer together, Gagliuffi said.
Planets or failed stars?
Galaxies are filled with stars, but they also include faint drifting objects with characteristics that make their status debatable. Such objects can be classified either as planets or as failed stars, given a blurry dividing line between the two.
That’s the case for the two objects Gagliuffi identified in a search for failed stars known as brown dwarfs. Gagliuffi sought brown dwarfs that could help her probe the lower boundary of what makes a star.
Unlike stars, brown dwarfs fail to fuse “normal” hydrogen in their interior. But these odd objects are apparently capable of fusing deuterium,
The newfound pair weigh in at roughly 15 and 14 times the mass of Jupiter. But the error bars associated with those estimates are wide enough that they may actually be in the planetary range.
“Their mass is straddling the deuterium-burning limit,” Gagliuffi said.
So, the twins could be a pair of planets dancing around a central point of mass (in which case they would be the history-making exoplanet binary), but they could also be a pair of brown dwarfs, or a brown dwarf hosting a massive gas giant planet.
To complicate the matter, both brown dwarfs and young gas giants produce light so weak that it is difficult to study their composition or differentiate them from one another.
And massive young planets produce heat from within, slowly cooling over their lifetimes. Gagliuffi’s studies show the pair are between 200 million and 300 million years old — young enough to confuse the issue.
Pairs of brown dwarfs are abundant throughout the Milky Way galaxy, but young binaries are not so common, Gagliuffi said. If the siblings turn out to be failed stars, they could provide intriguing insights into their family’s formation history.
Binary worlds also are thought to be rare. Our solar system is considered by some to host one pair of planets. The dwarf planet Pluto and its largest moon Charon orbit a point of mass outside the boundaries of each, making Pluto-Charon a binary system. No other binary planets are known outside of the sun’s orbit.
The newfound twin worlds drift through what Gagliuffi calls “a whole zoo of different stars,” only about 926 million miles (1.49 trillion kilometers) apart. While that sounds like an enormous distance — it is 10 times the distance between the Earth and the sun, after all— it’s actually extremely close for worlds from two different systems. She and her colleagues think it’s unlikely that the pair are just drifting close to one another by chance.
Given that they’re so close, it’s extremely likely that they’re bound,” Gagliuffi said.
It’s possible that the pair is connected to a third, more distant star that they orbit together. No such star has been identified, but many binary systems are actually triples, and Gagliuffi will look for a parent star as she continues this work.
Of course, the pair may also be drifting alone without adult supervision.
Is anyone else out there? Humans have asked this question ever since we could look up at the stars, but hundreds of thousands of years later, we still don’t have a satisfactory answer. Logic would seem to dictate that there’s other intelligent life out there, and yet it also suggests that if there is, it may have found us by now. While we may not have an answer for another few decades — if ever — we are slowly but surely getting closer.
A panel called “First Contact: Looking for Life in the Universe” at “Star Trek”: Mission New York Sept. 4 gave the audience a look at the current state of humanity’s search for extraterrestrial intelligence (SETI). The “Star Trek” mythos came up surprisingly few times for a panel calling itself a “Trek Talk,” but the subject matter was still appropriate, given the abundance of alien life on “Star Trek,” both familiar and bizarre. Dan Werthimer, the SETI chief scientist at the University of California, Berkeley, and Bobak Ferdowski from the NASA Jet Propulsion Laboratory oversaw the discussion, which covered the basics of astrobiology.
The two panelists spent a lot of time discussing the potential of finding life on Europa, an icy moon of Jupiter. Scientists have theorized that Europa has a liquid ocean buried beneath 30 miles of surface ice, and liquid water is potentially one of the most conducive environments for life to evolve, the panelists said. [13 Ways to Hunt for Intelligent Alien Life]
If we were to find life on Europa, Ferdowski and Werthimer explained, it would most likely be primitive. Humans may appear to be the dominant species on Earth, after all, but our overall biomass is pretty small when compared to wildly successful organisms such as bacteria, or even insects.
“Europa [may be] completely covered in water,” Werthimer explained. “That’s great for primitive life, but if you want technology, you’ve got to have some land surfaces as well.” Organisms on Earth, he said, have evolved to fill even the most extreme niches, “but it won’t necessarily evolve into something more complex than single-celled life … What are the pressures that make you want to go from ‘I can feed’ to standing and talking
In fact, the relative likelihood of finding primitive versus sapient life was one of the recurring themes of the talk. Werthimer believes that humanity may confirm the existence of primitive extraterrestrial life within the next 20 to 30 years, especially if scientists can get missions to Europa, but technological life is harder to pinpoint, as we don’t know how often it occurs.
Another potentially limiting factor is that intelligent life does not necessarily equate to technological life. Ferdowski and Werthimer pointed out that intelligent life (with varying degrees of what scientists would call “intelligence”) has evolved many times on Earth. Humans are the most obvious example, but dolphins, octopi and crows are all fairly clever creatures, to say nothing of the other great apes, which share a lineage with humans.
Even if there’s another technological civilization somewhere nearby, scientists are not exactly sure how to contact them. Radio signals seem like a safe bet; indeed, nearby stars have already seen “The Simpsons” and “I Love Lucy” from Earth’s TV broadcasts. On the other hand, while radio signals travel at the speed of light, that won’t do much good for an exoplanet that could be tens of thousands of light-years away.
On the flip side, given how fast life can (theoretically) arise and evolve on a planet, other civilizations could be millions or even billions of years ahead of Earth. We would have no idea how to monitor their communications, and they might not even be interested in ours.
Ferdowski and Werthimer contrasted the Drake Equation, which suggests that sapient life in the universe should be at least somewhat common, and the Fermi Paradox, which questions why alien life is not observable if the universe teems with it. One potential answer to the Fermi Paradox includes an alien version of the “Star Trek” Prime Directive, which prohibits interference with less advanced cultures. Another suggests that not all technological civilizations are necessarily driven by exploration, and may have directed their efforts inward to cultural matters instead.
Assuming that scientists can find life, however, there is (at least) one very important question to answer: Does it resemble humanity on a genetic level?
“Did it have a different biogenesis?” Ferdowski asked. “If it’s exactly the same as us, that probably doesn’t mean there were two independent origins of life.” In other words, if scientists find alien life that follows the basic biological dogma, such as translating DNA to RNA to proteins, it’s very likely that all life in the solar system originated from a common precursor
This theory, known as panspermia, suggests that extraordinarily simple, hardy life (or proto-life) could travel between planets aboard asteroids or other interplanetary debris. While this is harder to do once you get outside of a given solar system, it’s entirely possible that life on Earth and, say, Europa could have originated from the same predecessor, the researchers said.
While Ferdowski and Werthimer did not come to any hard conclusions as to whether or not humanity can expect to find life, they did say that the question has far-reaching consequences, regardless of the outcome.
“It’s a profound question either way,” Werthimer said. “If we find the universe is teeming with life, we can learn a lot. If we find out that we are alone, that somehow life is incredibly rare out of the trillion planets, that’s very profound also.
“If we find out we’re alone,” he added, “that means we’d better take incredibly good care of the precious life here on Earth.”
The sites of meteorite impacts on Mars are often considered to be good places to look for life. After all, it’s most likely that if any trace of life (past or present) ever took hold on the Red Planet, it would most likely be preserved under the bedrock of Mars’ harsh surface. Should there be a recent impact, could we search the debris to seek-out this recently excavated pristine rock for life?
Alas, in new research, this kind of impact crater search could be a fool’s errand; the energy of the impact likely sterilized any material we’d consider organic and related to life.
Researchers from Imperial College London carried out simulations of meteorite impacts in the lab to see how organic compounds fared when exposed to the kinds of impact pressures they could experience on Mars.
What they found wasn’t very promising if we hope to find evidence of life inside impact craters. For example, organic compounds associated with basic microbial and algal life (known as long chain hydrocarbon-dominated matter) were destroyed by the pressure of impact. On the other hand, other organic compounds associated with plant life (known as aromatic hydrocarbons) were chemically altered, but, according to a press release, “remained relatively resistant to impact pressures.”
Meteorites often contain organic chemicals not related to life that are resistant to the pressures of massive impacts.
So far, there has been little evidence of organics found that would suggest any kind of life has ever existed on Mars, but this new research provides an insight to what could be a previously overlooked complication in that search for life.
“We’ve literally only scratched the surface of Mars in our search for life, but so far the results have been inconclusive,” said Mark Sephton of Imperial College London. “Rocks excavated through meteorite impacts provide scientists with another unique opportunity to explore for signs of life, without having to resort to complicated drilling missions. Our study is showing us is that we may need to be nuanced in our approach to the rocks we choose to analyse.”
Rather than relying on computer simulations of meteorite impacts, the researchers used a piston cylindrical device to recreate the pressures and temperatures associated with a range of impact energies on various materials. They will continue to carry out these lab tests to see what energies give hypothetical Mars life the best chance of leaving their biological signature and which will pulverize their biology into oblivion.
“The study is helping us to see that when organic matter is observed on Mars, no matter where, it must be considered whether the sample could have been affected by the pressures associated with blast impacts,” added Wren Montgomery, also from Imperial. “We still need to do more work to understand what factors may play an important role in protecting organic compounds from these blast impacts. However, we think some of the factors may include the depths at which the rock records are buried and the angles at which meteorites hit the Martian surface.”
As we plan further exploration of the Martian surface, the more we can learn about where potential signs of Mars life could be hiding the better as, for now, we can’t assume that every crater will be a Mars biology goldmine.
Could there be a way to find bacterial structures on another planet? And if so, how important might these bacteria be in making a planet life-friendly? These are some of the questions that could be answered through studies on stromatolites, which are mounds of calcium-carbonate rock that are built up through lime-secreting cyanobacteria (bacteria that use photosynthesis for energy).
The research into the life-giving potential of these “living fossils” is based on small microbes in Australia, but the results could help us identify fossil evidence of life on other planets, in particular Mars, said Erica Suosaari, a science fellow for Bush Heritage Australia, a non-profit conservation and land management organization. Suosaari is based at Hamelin Station Reserve, Western Australia, a 500,000-acre property that borders one of the world’s most diverse and abundant examples of marine stromatolites, the Hamelin Pool Marine Nature Reserve.
“Looking for evidence of life in the rocks is like finding a needle in the haystack,” wrote Suosaari in an e-mail. “If stromatolites have definitive bio-signatures — such as self organized morphologies that are indicative of life processes — then it may be possible to look for that ‘signature’ in rocks on the surface of other planets and significantly reduce the size of that haystack
A paper based on Suosaari’s research at Hamelin Pool entitled “New multi-scale perspectives on the stromatolites of Shark Bay, Western Australia,” was published in the journal Scientific Reports earlier this year.
Funding for the collaborative research was provided by a consortium of oil companies (Chevron, Shell, Repsol and BP) who are interested in modern microbial carbonate environments to develop models for subsurface reservoirs and source rocks. Additional support for genomics analyses was provided by the Exobiology and Evolutionary Biology element of the NASA Astrobiology Program.
Learning more about ancient structures
On Earth, microbial communities responsible for creating stromatolites were essential in making the planet life-friendly. These stromatolite-forming cyanobacteria were the first living organisms to generate energy from the Sun using photosynthesis while creating oxygen as a byproduct. Over billions of years, cyanobacteria have changed Earth’s atmosphere from 1 percent oxygen to more than 20 percent oxygen, a composition that has allowed complex life evolve.
Suosaari’s research zeroes in on the stromatolites of Hamelin Pool, the most abundant and diverse modern assemblage of these microbial structures, which dominate nearly the entire 135 km of the coastline. Previous research into stromatolites identified them by the types of microbial mats colonizing the surface of the structure, a direct response of where the stromatolite resides in the tidal zone. Each lamination recorded in the stromatolite is thereby a record of a former surface mat. Her team instead classified stromatolites by their shape, revealing that certain shapes prefer to cluster in certain areas of the pool. Their investigation also showed that modern stromatolites have more in common with ancient stromatolites than previously thought.
“Modern marine stromatolites are often regarded as poor analogs of ancient stromatolites as a result of their grainy internal textures, which contrast with the fine grained nature of most ancient stromatolites,” Suosaari said.
By contrast, her team found out that in Hamelin Pool, the microbial communities commonly produce a fine-grained limestone known as micrite (microcrystalline calcite) creating stromatolite structures that are similar to the ancient stromatolites seen in the fossil record.
Furthermore, the stromatolite types in Hamelin Pool are dominated by a coccoid cyanobacterium that traces its lineage back 2 billion years to an ancient form of this cyanobacteria, called Eoentophysalis. This provides yet another similarity back to ancient times, Suosaari said. This means that standing along the shorelines of Hamelin Pool and gazing out onto the stromatolites, we are essentially looking through a window to early Earth at microbes of the same ancient lineage, pumping out oxygen and continuing to undertake processes that have been happening for billenia. There is not another place on the planet where this can be observed at such a scale.
The stromatolites studied were in a small region of Australia, but Suosaari said that as a whole, similar microbial communities could potentially be exported to other places — such as Mars — to make other locations in the Solar System more life-friendly to humans.
Suosaari said she thought of stromatolites when reading about SpaceX founder Elon Musk’s plans to bring life to the planet Mars. She suggested that because these stromatolite-building microbial communities produce oxygen, they could potentially make the Red Planet more life-friendly.
“Obviously with Elon Musk’s plans, we don’t have billions of years to shape the atmosphere if he is planning to move life there in the coming years, and Mars has less than 1 percent of the atmosphere of Earth,” she acknowledged. “But I begin to think about photosynthesizing microbial mats and how they have prevailed for billions of years; it’s a kind of resilience and longevity that our species hasn’t yet achieved. Perhaps we should look to these microbial communities to generate oxygen on the Red Planet at a small scale.”
The space agency announced Friday that plans are moving ahead for the robotic rover to launch in the summer of 2020 and land on Mars in February 2021.
The new rover also is designed to test the planet for usable resources, such as oxygen, that will be needed for future missions to Mars that will include humans.
The Mars Curiosity rover, which has been working on the Red Planet since August 2012, has been searching for evidence that the planet could have ever sustained life – even in microbial form.
The new rover will take the next step, looking for evidence of life.
“The Mars 2020 rover is the first step in a potential multi-mission campaign to return carefully selected and sealed samples of Martian rocks and soil to Earth,” said Geoffrey Yoder, acting associate administrator of NASA’s Science Mission Directorate, in a statement. “This mission marks a significant milestone in NASA’s Journey to Mars – to determine whether life has ever existed on Mars, and to advance our goal of sending humans to the Red Planet.”
The new vehicle, unofficially dubbed the Mars 2020 rover, is expected to explore a region of the planet where NASA scientists expect that the ancient environment had been favorable to support microbial life.
The rover will drill into rocks, collect samples and ready them for a return trip to Earth as part of a future Mars mission.
In an attempt to save money on the project, NASA plans to base the rover’s design on that of its predecessor, Curiosity.
Scientists want to study the samples for evidence of past life but also for materials that could pose a threat to humans on a future Mars mission.
NASA is expected to send astronauts to Mars in the 2030s.
As NASA’s New Horizons probe speeds toward a possible encounter with an object beyond the orbit of Pluto, the spacecraft has made observations of another icy object located in the same outer region of the solar system.
New Horizons finished its close encounter with Pluto last July and since then has completed two sets of observations on an object in the Kuiper Belt, the band of objects beyond the orbit of Neptune. The icy body is known as 1994 JR1 and orbits about 32 astronomical units away from the sun (an astronomical unit is the distance from the Earth to the sun). New Horizons’ view of the faint, icy body can be seen in this video from Space.com.
The observations put a stop to the hypothesis that JR1 may be a satellite of Pluto, New Horizons science team member Simon Porter said in a statement from NASA.
“Combining the November 2015 and April 2016 observations allows us to pinpoint the location of JR1 to within 1,000 kilometers (about 600 miles), far better than any small [Kuiper Belt object],” said Porter, a postdoctoral planetary scientist at the Southwest Research Institute in Colorado.
The team also figured out how fast the 90-mile-wide (150 km) object is rotating, using observations taken in April. Changes in light reflected off of JR1’s surface showed that the object rotates once every 5.4 hours, which is considered relatively quick for a KBO.
These observations will serve as practice for the possible 20 other objects New Horizons can see in the Kuiper Belt through its extended mission. If the New Horizons extended mission receives approval from NASA, the probe will do close-up observations of 2014 MU69 on Jan. 1, 2019.
New atmospheric insights
Meanwhile, researchers continue to analyze data from last year’s Pluto encounter. Team members now have new insights into the dwarf planet’s tenuous atmosphere after looking at starlight passing through the wispy gas, according to the NASA statement.
Roughly four hours after New Horizons made its closest approach to Pluto, on July 14, the spacecraft’s ultraviolet spectrometer instrument looked at two stars moving behind Pluto and its atmosphere (astronomers call this a stellar occultation).
“The light from each star dimmed as it moved through deeper layers of Pluto’s atmosphere, absorbed by various gases and hazes,” NASA wrote in a second press release.
The spectrometer confirmed previous measurements from New Horizons showing that Pluto’s upper atmosphere is up to 25 percent colder (and thus more compact) than what scientists expected before New Horizons flew by. The instrument also confirmed a calculation that nitrogen molecules escape the dwarf planet’s atmosphere at a rate of about 1,000 times lower than expected.
Stellar occultations of 1994 JR1 were also performed using light from the sun. This allowed New Horizons to confirm the atmospheric temperature and structure, measure the escape rate of nitrogen molecules from the atmosphere, and detect the presence of various gases (including nitrogen, methane and acetylene).
Some of Saturn’s icy moons may have been formed after many dinosaurs roamed the Earth. New computer modeling of the Saturnian system suggests the rings and moons may be no more than 100 million years old.
Saturn hosts 62 known moons. All of them are influenced not only by the gravity of the planet, but also by each other’s gravities. A new computer model suggests that the Saturnian moons Tethys, Dione and Rhea haven’t seen the kinds of changes in their orbital tilts that are typical for moons that have lived in the system and interacted with other moons over long periods of time. In other words, these appear to be very young moons.
“Moons are always changing their orbits. That’s inevitable,” Matija Cuk, principal investigator at the SETI Institute and one of the authors of the new research, said in a statement. “But that fact allows us to use computer simulations to tease out the history of Saturn’s inner moons. Doing so, we find that they were most likely born during the most recent 2 percent of the planet’s history.
The age of Saturn’s rings has come under considerable debate since their discovery in the 1600s. In 2012, however, French astronomers suggested that some of the inner moons and the planet’s well-known rings may have recent origins. The researchers showed that tidal effects — which refer to “the gravitational interaction of the inner moons with fluids deep in Saturn’s interior,” according to the statement — should cause the moons to move to larger orbits in a very short time.
“Saturn has dozens of moons that are slowly increasing their orbital size due to tidal effects. In addition, pairs of moons may occasionally move into orbital resonances. This occurs when one moon’s orbital period becomes a simple fraction of another. For example, one moon could orbit twice as fast as another moon, or three times as fast.
Once an orbital resonance takes place, the moons can affect each other’s gravity, even if they are very small. This will eventually elongate their orbits and tilt them from their original orbital plane.
By looking at computer models that predict how extended a moon’s orbit should become over time, and comparing that with the actual position of the moon today, the researchers found that the orbits of Tethys, Dione and Rhea are “less dramatically altered than previously thought,” the statement said. The moons don’t appear to have moved very far from where they were born.
To get a more specific value for the ages of these moons, Cuk used ice geysers on Saturn’s moon Enceladus. The researchers assumed that the energy powering those geysers comes from tidal interactions with Saturn and that the level of geothermal activity on Enceladus has been constant, and from there, inferred the strength of the tidal forces from Saturn.
Using the computer simulations, the researchers concluded that Enceladus would have moved from its original orbital position to its current one in just 100 million years — meaning it likely formed during the Cretaceous period. The larger implication is that the inner moons of Saturn and its gorgeous rings are all relatively young. (The more distant moons Titan and Iapetus would not have been formed at the same time.)
“So the question arises — what caused the recent birth of the inner moons?” Cuk said in the statement. “Our best guess is that Saturn had a similar collection of moons before, but their orbits were disturbed by a special kind of orbital resonance involving Saturn’s motion around the sun. Eventually, the orbits of neighboring moons crossed, and these objects collided. From this rubble, the present set of moons and rings formed.”
The research is being published in the Astrophysical Journal
NASA’s planet-hunting Kepler space telescope continues to zero in on the first “alien Earth” despite being hobbled by a malfunction more than two years ago.
Last Thursday (July 23), mission scientists announced the discovery of Kepler-452b, which they and NASA officials described as the most Earth-like exoplanet yet found. Kepler-452b circles a sunlike star at about the same distance Earth orbits the sun, but the alien world is about 60 percent wider than our home planet, so it’s not a true “Earth twin.”
Kepler-452b “is the closest thing that we have to another place that somebody else might call home,” Jon Jenkins, Kepler data analysis lead at NASA’s Ames Research Center in Moffett Field, California, said during a news conference Thursday. [Exoplanet Kepler 452b: Closest Earth Twin in Pictures]
While the discovery of Kepler-452b is new, the observations that led to it are several years old. The planet was dug out of data Kepler gathered during the first four years of its original planet hunt, which came to an end in 2013.
The main goal of the $600 million Kepler mission is to determine how common Earth-like planets are across the Milky Way galaxy.
During its original round of operations, the Kepler spacecraft stared at more than 150,000 stars continuously and simultaneously, watching for tiny brightness dips that could betray the presence of a planet crossing, or “transiting,” its host star’s face. This work required extremely precise pointing, an ability Kepler lost when the second of its four orientation-maintaining reaction wheels failed in May 2013.
Kepler generally needs to observe multiple transits to detect a planet, so it can take a while for the observatory to spot a potentially habitable world. (Earth, after all, would transit the sun from a hypothetical alien Kepler’s perspective just once a year.) Small, rocky planets also present a signal-to-noise issue that can be mitigated by observing multiple transits.
Kepler team members have therefore long maintained that the most interesting Kepler finds should come at relatively late stages in the mission. So, while Kepler observed beyond the 3.5 years prescribed by the prime mission plan, the failure of the second reaction wheel was initially “crushing,” Jenkins said.
But only initially, for Kepler scientists have gotten better and better at analyzing the observatory’s huge dataset and pulling out intriguing finds from the original planet hunt, team members said.
For example, the discovery of Kepler-452b was announced along with 521 newfound planet “candidates,” bringing Kepler’s total tally of potential planets to 4,696. Just 1,030 of these worlds have been confirmed by follow-up observations or analysis, but about 90 percent of them should end up being the real deal, mission scientists have said. [10 Exoplanets That Could Host Alien Life]
Furthermore, 11 of the newly detected 521 candidates are similar to Kepler-452b: They’re less than twice Earth’s diameter and reside in their host stars’ “habitable zone,” that just-right range of distances in which liquid water could exist on a planet’s surface.
Such detections were made with the aid of new software that automated some parts of the data-analysis process that had previously been done manually, said Kepler research scientist Jeff Coughlin, of the Search for Extraterrestrial Intelligence (SETI) Institute in Mountain View, California.
Continued improvements in software and analysis techniques should result in more discoveries down the road, Coughlin added. Indeed, he said, the team plans to release another “catalog” of Kepler finds next year.
“We’re really optimistic that we’re going to continue to discover even more small, habitable-zone planets,” Coughlin said during Thursday’s news conference.
Kepler’s enormous dataset is publicly archived, so it should give academics and citizen scientists plenty to chew on far into the future, he added.
“I really expect that discoveries will be coming from Kepler for the next several decades,” Coughlin said.
Regardless of what happens in the future, Kepler’s discoveries have already revolutionized exoplanet research. The spacecraft’s finds suggest, among other things, that every Milky Way star hosts at least one planet on average; that rocky planets are extremely common throughout the galaxy; and that about 20 percent of all stars in the Milky Way host a roughly Earth-size planet in their habitable zones.
And while team members pore over data from the original mission, Kepler continues to gather data during a new mission called K2. The observatory’s handlers figured out a way to improve its pointing abilities using sunlight pressure as a sort of ersatz reaction wheel, and Kepler is now studying a variety of cosmic objects and phenomena, from distant supernova explosions to comets and asteroids in our own solar system.
The K2 plan also calls for continued exoplanet hunting, though on a much lesser scale than Kepler used to perform. (NASA announced the new mission’s first alien-planet discovery this past December.)
The failure of the second reaction wheel “is kind of the best worst thing that could’ve ever happened to Kepler,” Jenkins said. “It really broadens the field of exoplanets. It broadens the science that we can do with this phenomenal spacecraft.”
NASA announced that it is collaborating with Microsoft to enable astronauts onboard the orbiting space station to use the company’s virtual reality headset.
Two pairs of Microsoft’s HoloLens computerized eyeglasses are scheduled to be sent to the space station when SpaceX launches its seventh commercial resupply mission on June 28.
“HoloLens and other virtual and mixed reality devices are cutting edge technologies that could help drive future exploration and provide new capabilities to the men and women conducting critical science on the International Space Station,” Sam Scimemi, NASA’s director of the space station program, said in a statement. “This new technology could also empower future explorers requiring greater autonomy on the journey to Mars.”
Microsoft unveiled HoloLens in January at a Windows 10 event where CEO Satya Nadella said the device will be the world’s first holographic computing platform. The device is designed to allow users to see high-definition holograms with surround sound. They’re also built to understand voice commands and hand gestures.
The project that NASA and Microsoft are teaming up on has been dubbed Sidekick and is focused on helping astronauts who need to perform various tasks off-Earth.
By using HoloLens, which look much like a pair of wrap-around sunglasses and are expected to ship on July 29 along with Windows 10, the astronauts should be able to perform some on-station tasks with less training and be more efficient in the work they’re doing.
NASA already has tested the devices on board NASA’s Weightless Wonder C9 jet to make sure they work as expected in gravity-free environment.
Alien worlds with helium skies might be fairly common throughout the universe, researchers say.
One such helium-rich exoplanet might have already been discovered about 33 light-years from Earth, scientists added.
In the past two decades or so, astronomers have confirmed the existence of more than 1,800 extrasolar planets. Among these exoplanets are strange worlds called warm Neptunes — planets that, at 10 to 20 times the mass of Earth, are about the mass of “cold Neptunes” such as Uranus and, naturally, Neptune, but are as close, or closer, to their stars than Mercury is to our sun.
These warm Neptunes can reach scorching temperatures of more than 1,340 degrees Fahrenheit (725 degrees Celsius), and complete orbits around their stars in as little as one or two days. [The Strangest Alien Planets (Gallery)]
Astronomers had assumed that Neptune-size exoplanets would possess rocky or liquid cores wrapped in atmospheres dominated by hydrogen and helium, much like the giant planets in our own solar system. However, planetary scientist Renyu Hu at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, and his colleagues reasoned that warm Neptunes are so close to their stars that stellar radiation may have dramatically altered their atmospheres.
The researchers discovered that warm Neptunes could often have atmospheres enriched with helium. “They could be fairly common,” Hu told Space.com.
The high levels of extreme ultraviolet radiation that warm Neptunes would receive from their stars would cause their hydrogen to waft away.
“Hydrogen is four times lighter than helium, so it would slowly disappear from the planets’ atmospheres, causing them to become more concentrated with helium over time,” Hu said in a statement.
A warm Neptune with a fairly small atmosphere could become helium-dominated over the course of up to 10 billion years, Hu said. (For comparison, Earth is about 4.5 billion years old.)
One way to detect such a planet would be to note the color of its sky. Neptune is a brilliant azure blue because of methane. However, the scarcity of hydrogen on helium-atmosphere worlds would mean that methane, which is composed of one carbon atom and four hydrogen atoms, would be rare, while carbon monoxide and carbon dioxide, which are composed of carbon and oxygen, would be far more common. As such, a helium-sky planet would probably appear grey or white, researchers said.
One warm Neptune called GJ 436b that is peculiarly low in methane might be such a helium-rich planet. NASA’s Spitzer Space Telescope found that GJ 436b, which is located about 33 light-years from Earth, is also rich in carbon monoxide.
A number of other features would also help set helium-sky worlds apart. For instance, an atmosphere rich in helium would be puffier than one made of carbon dioxide or nitrogen because helium is lighter than either of those two gases, “and this feature makes the helium atmosphere more observable,” Hu said.
In addition, because helium is easier to heat than hydrogen, a helium-rich planet is more likely to have a hot spot facing its star than a hydrogen-rich world.
Future research could use NASA’s Hubble Space Telescope to look for more warm Neptunes with carbon monoxide and carbon dioxide in their atmospheres, and NASA’s upcoming James Webb Space Telescope might one day directly detect helium in the skies of these planets.
“Any planet one can imagine probably exists, out there, somewhere, as long as it fits within the laws of physics and chemistry,” study co-author Sara Seager of MIT said in the same statement. “Planets are so incredibly diverse in their masses, sizes and orbits that we expect this to extend to exoplanet atmospheres.”
Hu, Seager and their colleague Yuk Yung of JPL detailed their findings in a paper that will appear today (June 24) in the Astrophysical Journal.
Where can scientists find clues to help them locate and understand life beyond Earth? According to speakers at the 2015 Astrobiology Science Conference, the hunt begins in many locations, from planets beyond our solar system to the ground beneath our feet.
At a news briefing hosted by NASA, three speakers discussed a wide range of ways that scientists are assisting in the search for life elsewhere in the universe. Those efforts include studies of extreme life-forms on Earth, photographs of the sun glinting off Earth’s ocean, and studies in Antarctica that will assist a mission to one of Jupiter’s icy moons.
John Grunsfeld, associate administrator for science at NASA, opened the panel discussion with remarks about his own passion and enthusiasm for the search for life, and how it fits into NASA’s overall mission to “innovate, explore, discover and inspire.”
Alexis Templeton, an associate professor of geological sciences at the University of Colorado-Boulder, discussed the NASA-funded “Rock-Powered Life Team,” for which she is principal investigator.
“[We’re] quite interested in the capability of rocks to store energy within them to be used to power biological systems,” Templeton said. “Essentially, there’s a fundamental understanding that rocks have within them, depending on their chemistry, the ability to release electrons or components that can fuel and power different systems essentially much like fuel cells do. And one of the big questions at the moment is how we can couple the energy that’s stored within rocks into biological systems.”
If rocks can serve as an energy source for life, it might opened up new possibilities for where life could thrive in the universe. In particular, it could mean that organisms don’t need direct exposure to sunlight, but could live in subsurface environments.
Templeton said the group is investigating life-forms found in the deserts of Oman, where rocks formed in the Earth’s mantle have come to the surface. Prolonged contact between the rocks and pools of water has “changed the water chemistry progressively,” Templeton said, making it highly alkaline — a “rare type of water to find on Earth.” Life-forms discovered in these pools are not only surviving in the alkali environments, but are optimized for them.
“This is, then, very exciting to start to imagine that there’s biological life-forms that may be well adapted in the subsurface environment to be sustained by the reactions between these rocks and water,” Templeton said.
Britney Schmidt, an assistant professor of earth and atmospheric sciences at the Georgia Institute of Technology, discussed the search for life in sub-surface oceans such as those found on Jupiter’s icy moons and other icy worlds.
“We think a lot about Mars in the search for life in the solar system, but there’s a whole host of ice-rich worlds that harbor subsurface oceans,” Schmidt said. “And these are important places to think about in the search for life, even within our own solar system.”
NASA recently announced a suite of instruments that the agency selected to go aboard a planned satellite mission to Europa, one of Jupiter’s moons. Scientists say its possible life could exist beneath the icy surface of Europa, in the immense ocean that lies below.
Currently, Schmidt is principal investigator for the NASA-funded project Sub-Ice Marine and Planetary Analog Ecosystems, or SIMPLE, a project that Schmidt says will assist future missions to icy worlds.
“[We] work with a number of different vehicles, a number of different remote sensing and in-situ sensing platforms, to study our ocean the same way we’d want to study the ocean of [Jupiter’s moons] Europa or Enceladus,” Schmidt said.
The project includes a vehicle called “Icefin,” which is exploring the ocean below the Antarctic ice. Another instrument, called “Artemis,” will perform long-range exploration under the ice; another project will conduct ice-penetrating radar studies of the ice shelves of the Antarctic, all of which are “perfect analogs” for the work that is set to be done by radar instruments flying over Europa. [Photos: Europa, Mysterious Icy Moon of Jupiter]
A glimmer of life
Vikki Meadows, a professor of astronomy and principal investigator at the University of Washington’s Virtual Planetary Laboratory in Seattle, spoke last about studies that could assist in identifying signs of life through direct observations of exoplanets.
She presented an image taken by the LCROSS satellite (before it crashed into the moon in 2009) of the Earth as a partially illuminated crescent. The curved sliver of light was not uniform — it featured a slightly brighter section right near its midpoint. That, said Meadows, was a glint of sunlight reflecting off the ocean.
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This “glint effect,” Meadows said, is something that scientists theorized might reveal the presence of an ocean on a distant exoplanet. But the images taken by LCROSS are the first “glint” data ever collected.
“By comparing our models and that data, we were able to confirm that in fact our models are accurate,” Meadows said. “We have more confidence now about predicting the type of signals we might be able to detect from extrasolar planets when we go for the gold and actually try to detect an ocean on another planet.”
Meadows’ team has also done work to help narrow down what kind of elements and molecules in a planet’s atmosphere might indicate the presence of life — in particular, what the presence of oxygen says about the presence or absence of life — and how to spot false positives.
“We now are getting a much more mature view of what we should be looking for and what might fool us,” Meadows said. “We know in particular which targets we should choose preferentially that will help us avoid these false positives for life and also what other things in the planetary spectrum we should look for that might help us figure out what’s going on.”
The panel’s comments reflected just a sampling of the research being presented at the meeting this week, and a small indication of the work that is slowly but steadily moving the scientific community closer to the possibility of identifying life elsewhere in the universe..
“Are we alone? Is there another civilization out there? Is there any other life out there?” Grunsfeld said in his opening remarks. “The fact that we’re here, and the fact that life is so complex on Earth, rocks survive on a tiny bit of chemical energy, to me is convincing that there is a very high probability there’s life elsewhere.”
Scientists using several telescopes, including NASA’s Chandra X-ray Observatory, found evidence that a planet in an ancient cluster of stars on the edge of the Milky Way drifted too close to a white dwarf star and was ripped apart. NASA officials explained the discovery in a video on the planet’s death by white dwarf.
White dwarf stars start out as any normal star about the size of the sun, but eventually swell into red giants while they burn up the hydrogen in their core and fuse it into helium. When all the hydrogen is gone, only the star’s core is left —a dense sphere with a radius about one hundredth the size of the original star, but with almost the same mass.
The dead stars’ density creates a strong gravitational pull, more than 10,000 times stronger than the gravitational force at the surface of the sun, according to NASA officials.
That force, and its associated tides, could have the power to pull apart a planet that passes too close, astronomers said. They estimate the destroyed planet had about a third of the mass of Earth and the white dwarf has approximately 1.4 times the mass of the sun.
Researchers using the European Space Agency’s INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) discovered the possibility that a white dwarf tore a planet apart when they found an unexpected source of X-ray radiation in globular star cluster NGC 6388. They initially thought the radiation was due to hot gas swirling toward an intermediate-mass black hole thought to be at the center of the cluster.
A second look with Chandra X-ray Observatory, however, revealed that the X-rays were actually coming from a point off to the side of the cluster’s possible black hole center. Scientists continued to monitor the radiation for 200 days with the X-ray telescope on board NASA’s Swift gamma-ray burst observatory, an international mission that aims to solve the mystery of what causes brief and intense flashes of gamma-ray radiation in space.
As scientists monitored the X-rays, the radiation dimmed at a rate that agrees with current theories of how a planet ripped apart by the gravitational tidal forces of a white dwarf would react. These theories predict the debris from a planet shredded by a white dwarf would be heated and glow in X-rays as it falls onto the white dwarf.
“While the case for the tidal disruption of a planet is not iron-clad, the argument for it was strengthened when astronomers used data from the multiple telescopes to help eliminate other possible explanations for the detected X-rays,” NASA officials wrote in a statement.
Astronomers have spotted a dead star polluted with heavy elements, suggesting that the star recently chowed down on a water-laced asteroid.
The destructive process hints at how asteroids probably delivered water to Earth billions of years ago. But it also hints at how asteroids likely deliver water to exoplanets in other planetary systems.
“Our research has found that, rather than being unique, water-rich asteroids similar to those found in our solar system appear to be frequent,” lead researcher Roberto Raddi from the University of Warwick, said in a statement. “Accordingly, many planets may have contained a volume of water, comparable to that contained in the Earth.” [Related: In Search for Alien Life, Follow the Water]
Astronomers once thought that white dwarfs — the Earth-size remnants of low-mass stars like our sun — were pristine. Their intense gravity should pull the heaviest elements down into their depths relatively quickly (thousands of years at most). “In old white dwarfs (hundreds of millions of years old), like the one we observed, one would not expect any heavy element to stay in their atmospheres for long,” Raddi told Space.com in an email.
But when the team observed the white dwarf in question (known as SDSS J1242+5226), they saw that it was smothered in oxygen, magnesium, silicon, iron and other heavy elements. Even hydrogen was far more abundant than expected. These elements match what astronomers expect to see in a water-rich asteroid.
It’s likely that the asteroid passed close to the white dwarf, whose intense gravity shredded it into smaller particles. These particles then formed a disk around the dead star, and slowly rained down over time — polluting the star’s surface with its elements. Because those elements are still expected to sink to the center of the star, the destructive event probably happened fairly recently, Raddi said.
The astronomers suspect that the asteroid was initially comparable in size to Ceres, the largest known asteroid in the solar system, Raddi said. And it likely contained enough water to fill 30 percent of the Earth’s oceans.
The result sheds light on how asteroids can deliver water to stars and other orbiting bodies. Geologists don’t think Earth’s water has been here for too long. The moon-forming impact would have melted the Earth’s crust and mantle, vaporizing any water. Instead, asteroids likely delivered water to Earth in the young solar system.
And this research shows that this process was not unique to our solar system. It’s likely occurring throughout planetary systems in the galaxy, scientists said.
“Our work reinforces previous evidence that water-rich asteroids are common in other planetary systems,” Raddi said. “It also confirms that asteroids can deliver their constituents (rocks and ice) onto the surface of planets in the inner parts of the planetary systems orbiting other stars, likely within what is known as the habitable zone.”
The team made their observations on the U.K.-owned William Herschel Telescope in the Canary Islands, Spain. The study was published today (May 7) in the journal Monthly Notices of the Royal Astronomical Society.
The newfound exoplanets, known as HD 7924c and HD 7924d, are “super Earths” with masses about 7.9 and 6.4 times greater, respectively, than that of our home planet, researchers said. The planets orbit the star HD 7924, which lies just 54 light-years from the sun — a mere stone’s throw considering the size of the Milky Way, which is on the order of 100,000 light-years wide.
The discovery brings the number of known planets in the HD 7924 system to three. (Another super Earth, called HD 7924b, was spotted there in 2009.) HD 7924b, HD 7924c and HD 7924d all lie closer to their host star than Mercury does to the sun. They complete one orbit in five, 15 and 24 days, respectively, researchers said. [The Strangest Alien Planets]
“The three planets are unlike anything in our solar system, with masses seven to eight times the mass of Earth and orbits that take them very close to their host star,” study co-author Lauren Weiss, a graduate student at the University of California, Berkeley, said in a statement.
The research team discovered HD 7924c and HD 7924d using three different ground-based facilities — the Automated Planet Finder (APF) Telescope at Lick Observatory in California, the Keck Observatory in Hawaii and the Automatic Photometric Telescope (APT) at Fairborn Observatory in Arizona. (Keck also found HD 7924b in 2009.)
The research team, which was led by University of Hawaii (UH) graduate student BJ Fulton, used the combined observations of the three telescopes to detect tiny wobbles in the star HD 7924 caused by the gravitational pull of the two newfound planets, and then to verify the worlds’ existence.
Starspots, like sunspots on the sun, can momentarily mimic the signatures of small planets,” said co-author Evan Sinukoff, also a UH graduate student. “Repeated observations over many years allowed us to separate the starspot signals from the signatures of these new planets.”
The APF Telescope was recently revamped to make it fully robotic, and it now searches the skies for exoplanets without human oversight — a key milestone in the ongoing exoplanet hunt, researchers said.
“This level of automation is a game-changer in astronomy,” said co-author Andrew Howard, an astronomer at UH. “It’s a bit like owning a driverless car that goes planet shopping.”
Astronomers first found planets orbiting another star in 1992, and the exoplanet tally has now risen to nearly 2,000. More than half of these alien worlds have been discovered by NASA’s Kepler space telescope, which launched in March 2009.