exoplanets

On using modified extremophiles to seed new worlds

Synthetic biology has the potential to make organisms more resistant to radiation or temperature extremes,” she said. “You can mix and match genes and do all sorts of things that if you were breeding [organisms] would take forever.”
These modified extremophiles can shed light on a variety of astrobiological questions, including whether or not a planet is potentially habitable. “Say we find a planet, and it has a certain pH, temperature, and radiation regime,” Rothschild told me.
“That’s where we take up the challenge and go into the lab,” she continued. “We’ll say, ‘All right, let’s start with this one that can live at low pH and high temperature. Can we add the radiation resistance?’ Then, we can go back to the astronomers and say [habitability] is not impossible, because we just made something in the lab like that last week.

From We Might Create Alien Life in a Lab Before We Find It in Space

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Using NASA’s Kepler satellite, astronomers have found about 1,000 planets around stars in the Milky Way and they have also found about 3,000 other potential planets. Many of the stars have planetary systems with 2-6 planets, but the stars could very well have more planets than those observable with the Kepler satellite, which is best suited for finding large planets that orbit relatively close to their stars.
Planets that orbit close to their stars would be too scorching hot to have life, so to find out if such planetary systems might also have planets in the habitable zone with the potential for liquid water and life, a group of researchers from the Australian National University and the Niels Bohr Institute at the University of Copenhagen made calculations based on a new version of a 250-year-old method called the Titius-Bode law.

The Titius-Bode law was formulated around 1770 and correctly calculated the position of Uranus before it was even discovered. The law states that there is a certain ratio between the orbital periods of planets in a solar system. So the ratio between the orbital period of the first and second planet is the same as the ratio between the second and the third planet and so on. Therefore, if you knew how long it takes for some of the planets to orbit around the Sun/star, you can calculate how long it takes for the other planets to orbit and can thus calculate their position in the planetary system. You can also calculate if a planet is ‘missing’ in the sequence.

“We decided to use this method to calculate the potential planetary positions in 151 planetary systems, where the Kepler satellite had found between 3 and 6 planets. In 124 of the planetary systems, the Titius-Bode law fit with the position of the planets. Using T-B’s law we tried to predict where there could be more planets further out in the planetary systems. But we only made calculations for planets where there is a good chance that you can see them with the Kepler satellite,” explains Steffen Kjær Jacobsen, PhD student in the research group Astrophysics and Planetary Science at the Niels Bohr Institute at the University of Copenhagen.

In 27 of the 151 planetary systems, the planets that had been observed did not fit the T-B law at first glance. They then tried to place planets into the ‘pattern’ for where planets should be located. Then they added the planets that seemed to be missing between the already known planets and also added one extra planet in the system beyond the outermost known planet. In this way, they predicted a total of 228 planets in the 151 planetary systems.

“We then made a priority list with 77 planets in 40 planetary systems to focus on because they have a high probability of making a transit, so you can see them with Kepler. We have encouraged other researchers to look for these. If they are found, it is an indication that the theory stands up,” explains Steffen Kjær Jacobsen.

Planets that orbit very close around a star are too scorching hot to have liquid water and life and planets that are far from the star would be too deep-frozen, but the intermediate habitable zone, where there is the potential for liquid water and life, is not a fixed distance. The habitable zone for a planetary system will be different from star to star, depending on how big and bright the star is.

The researchers evaluated the number of planets in the habitable zone based on the extra planets that were added to the 151 planetary systems according to the Titius-Bode law.

***The result was 1-3 planets in the habitable zone for each planetary system.***

Out of the 151 planetary systems, they now made an additional check on 31 planetary systems where they had already found planets in the habitable zone or where only a single extra planet was needed to meet the requirements.

“In these 31 planetary systems that were close to the habitable zone, our calculations showed that there was an average of two planets in the habitable zone. According to the statistics and the indications we have, a good share of the planets in the habitable zone will be solid planets where there might be liquid water and where life could exist,” explains Steffen Kjær Jacobsen.

If you then take the calculations further out into space, it would mean that just in our galaxy, the Milky Way, ***there could be billions of stars with planets in the habitable zone***, where there could be liquid water and where life could exist.

He explains that what they now want to do is encourage other researchers to look at the Kepler data again for the 40 planetary systems that they have predicted should be well placed to be observed with the Kepler satellite.

Planets in the habitable zone around most stars, researchers calculate  – http://www.sciencedaily.com/releases/2015/03/150318074515.htm
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Aside from a small amount of water acquired by the youthful Earth in the form of hydrated silicate rocks, the great bulk of Earth’s water must have been delivered from beyond. The pummelling Earth received in its youth from asteroids and comets will have delivered the water that is so vital to life as we know it.

The problem is actually exacerbated by the collision that formed the moon. That giant impact occurred after the proto-Earth had differentiated – with the heaviest elements (such as iron and nickel) settling to our planet’s core. This means that the mantle and crust of the Earth, stripped off by the collision, would also have contained most of Earth’s water at the time.

Without the asteroid and comet collisions that have occurred since the moon’s formation, the Earth would most likely be dry and lifeless. But impacts are a stochastic, chance thing – some planetary systems will have architectures that are poorly set up from the point of view of the delivery of volatiles to any terrestrial worlds therein.

On the other hand, studies of the formation and evolution of the “hot Jupiters” – planets like Jupiter orbiting far closer to their hosts than Mercury orbits the sun – suggest that the inward migration of such planets could drag with them vast amounts of volatiles.

In those models, so much water is delivered to the inner reaches of those systems that any Earth-like planets that form are water worlds – drenched in oceans hundreds of kilometres deep.

While such worlds might well be teeming with life, it is unlikely that it would be easy to detect. Indeed, without continents, the oceans could be almost completely lifeless, with the only source of nutrients being volcanoes on the ocean floor.

If life on such water worlds did exist, it might be so deeply buried in the ocean that any sign of it would be extremely challenging to detect, particularly from a distance measured in tens or hundreds of light-years. As such, ocean worlds would most likely be poor targets for the initial stages of the search for life elsewhere.

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This is the background for an emerging aspect of the space weather discipline: planetary space weather. In this article, we explore what characterizes planetary space weather, using some examples throughout the solar system. We consider energy sources and timescales, the characteristics of solar system objects and interaction processes. We discuss several developments of space weather interactions including the effects on planetary radiation belts, atmospheric escape, habitability and effects on space systems. We discuss future considerations and conclude that planetary space weather will be of increasing importance for future planetary missions.

What characterizes planetary space weather?
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Using the Very Large Telescope Interferometer (VLTI) in near-infrared light, the team of astronomers observed 92 nearby stars to probe exozodiacal light from hot dust close to their habitable zones and combined the new data with earlier observations. Bright exozodiacal light, created by the glowing grains of hot exozodiacal dust, or the reflection of starlight off these grains, was observed around nine of the targeted stars.
From dark clear sites on Earth, zodiacal light looks like a faint diffuse white glow seen in the night sky after the end of twilight, or before dawn. It is created by sunlight reflected off tiny particles and appears to extend up from the vicinity of the Sun. This reflected light is not just observed from Earth but can be observed from everywhere in the Solar System.
The glow being observed in this new study is a much more extreme version of the same phenomenon. While this exozodiacal light—zodiacal light around other star systems—had been previously detected, this is the first large systematic study of this phenomenon around nearby stars.
In contrast to earlier observations the team did not observe dust that will later form into planets, but dust created in collisions between small planets of a few kilometres in size—objects called planetesimals that are similar to the asteroids and comets of the Solar System. Dust of this kind is also the origin of the zodiacal light in the Solar System.
“If we want to study the evolution of Earth-like planets close to the habitable zone, we need to observe the zodiacal dust in this region around other stars,” said Steve Ertel, lead author of the paper, from ESO and the University of Grenoble in France. “Detecting and characterising this kind of dust around other stars is a way to study the architecture and evolution of planetary systems.”

…

By analysing the properties of the stars surrounded by a disc of exozodiacal dust, the team found that most of the dust was detected around older stars. This result was very surprising and raises some questions for our understanding of planetary systems. Any known dust production caused by collisions of planetesimals should diminish over time, as the number of planetesimals is reduced as they are destroyed.
The sample of observed objects also included 14 stars for which the detection of exoplanets has been reported. All of these planets are in the same region of the system as the dust in the systems showing exozodiacal light. The presence of exozodiacal light in systems with planets may create a problem for further astronomical studies of exoplanets.
Exozodiacal dust emission, even at low levels, makes it significantly harder to detect Earth-like planets with direct imaging. The exozodiacal light detected in this survey is a factor of 1000 times brighter than the zodiacal light seen around the Sun. The number of stars containing zodiacal light at the level of the Solar System is most likely much higher than the numbers found in the survey. These observations are therefore only a first step towards more detailed studies of exozodiacal light.
“The high detection rate found at this bright level suggests that there must be a significant number of systems containing fainter dust, undetectable in our survey, but still much brighter than the Solar System’s zodiacal dust,” explains Olivier Absil, co-author of the paper, from the University of Liège. “The presence of such dust in so many systems could therefore become an obstacle for future observations, which aim to make direct images of Earth-like exoplanets.”

Very Large Telescope Interferometer detects exozodiacal light
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Russian astronomers spot second planet in Alpha Centauri system   

It is located outside the so-called habitable zone, or the orbital region around a star in which an Earth-like planet can possess liquid water on its surface and possibly support life.

“We believe that this planet may be located at a distance of 80 astronomical units /a unit of length, roughly the distance from the Earth to the Sun, which is 150 million kilometers/ and is orbiting around the centre of the binary star system Alpha Centauri AB with an orbital period of about 100 years,” Ivan Shevchenko, the head of the laboratory of planets and small bodies dynamics at the Pulkovo Observatory, told ITAR-TASS.

Russian astronomers spot second planet in Alpha Centauri system   

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Water clouds tentatively detected just 7 light-years from Earth

“It’s tentative,” he says, but “it’s the first evidence for water clouds” outside our solar system. Even within the solar system, observers can see water clouds on only Earth and Mars; the giant planets are so cold that ammonia ice clouds cover the water clouds on Jupiter and Saturn while the atmospheres of Uranus and Neptune block the view there.

Observers have previously discerned water vapor in the atmospheres of extrasolar planets, but Fortney says water clouds are a new phenomenon. “One of the things we don’t really know is how common partly cloudiness is,” he says. Venus, whose clouds consist of sulfuric acid, is totally cloudy, whereas Earth is partly cloudy. Faherty says the brown dwarf is also partly cloudy: About half is obscured by clouds.

Verifying the discovery will require spectra. Because the object is so dim, this will likely await the James Webb Space Telescope, which will be launched later this decade.

Water clouds tentatively detected just 7 light-years from Earth

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Exoplanet names will be put to public vote   

To kick things off, the IAU has created a list of 305 well-studied exoplanets. Starting in September, astronomy clubs and non-profit organisations will be able to register at a website and between them select 20 to 30 of these worlds to name. Each group will then be allowed to submit a name for one of these exoplanets, following the IAU’s naming rules. Once the suggestions are collected, they will be open to a public vote. The IAU will still have the final say, and will announce the results at its next general assembly in Hawaii in August 2015.

In case you’re wondering, names must be copyright-free, which may rule out calling a planet Alderaan or Westeros, for example. The IAU guidelines say names must be free for public use and “not subject to copyright royalties, as could be the case for names created in fiction works, like books, plays, movies, etc”.

The 305 worlds on the initial list were all discovered before 2009, which means the list excludes all the planets discovered by NASA’s Kepler space telescope. But the list does includes Gliese 581 d, which may not actually exist.

“There are no guarantees that all of the 305 exoplanets in this list will stand the test of time,” says Christensen. “Science changes all the time, and these objects are notoriously hard to detect. So changes to the list at a later stage are not impossible, and possibly Gliese 581 d could be such a case. For now, after careful considerations, it remains on the list although its existence is disputed.”

Exoplanet names will be put to public vote   

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In terms of the search for extraterrestrial intelligence (SETI), it may no longer be a matter of answering the “are we alone” question, some scientists say. Rather, just how crowded is the universe?

And if ET is out there, it may be possible to reach out with direct “radio waving” to potentially habitable exoplanets. This form of cosmic cryptography, called “Active SETI,” involves no longer merely listening for a signal but purposefully broadcasting to, and perhaps establishing contact with, other starfolk.

“It’s a subject of discussion, I’ll put it that way,” said Seth Shostak, senior astronomer at the SETI Institute in Mountain View, Calif. There have been many workshops and symposia over the years to discuss Active SETI, he said, and because it has a highly emotional component, “it’s like a third rail in a way,” he said.

Shostak told Space.com that he feels the topic is not something to worry too much about.

“But there may not be that perception in the broader public … that we have discussed this to death. They haven’t seen these discussions nor participated in them,” he said.

But exoplanet detections are making news around the world, Shostak said. “That’s putting the whole question of life in space in front of the public in a way that perhaps wasn’t true 20 years ago.”

Still, trying to figure out what’s the best thing to do, in terms of Active SETI, is a work in progress, Shostak said. “What is the best way to communicate? What do you do…just ping them with a carrier wave and you encode Wikipedia? If you are going to do it, what’s the best way to communicate?”

“[Hawking]’s right about our immaturity as a species,” Impey told Space.com, “but I think the argument is moot since intelligent civilizations are likely to be so sparsely distributed that communication in either direction is difficult or unlikely.”

Active SETI, Impey said, “makes us feel a little more proactive, but I think it’s a long shot worse than buying a lottery ticket.”

For Impey, the “promising approach” is not conventional SETI or broadcasting, but detection of civilizations by their energy or technology imprints, “and that avoids all the issues of intention and communication and the anthropocentric tangle people get into with that.”

“I am for passive SETI programs, and in fact would advocate for renewed government funding after a 20-year lapse,” Dick told Space.com. “That’s because the existence of extraterrestrial intelligence is one of the great unsolved mysteries of science.”

Dick said that the current NASA astrobiology hunt is centered on microbes, but surely there should be an effort to go beyond micro-organisms and search for complex life with whatever means are available.

“On the other hand, I would not propose government funding for messaging extraterrestrial intelligence. I think we need to find ET first, and then have a period where a team consisting of scientists, social scientists and humanities people consider what the message should be,” Dick said.

“Having said that, it would be very difficult to regulate individual or institutional projects that wish to attempt messaging extraterrestrial intelligence, and I would not advocate attempting to regulate,” Dick said. In his opinion, there is an equal chance that ET will be good or bad.

“We do not yet know enough about the evolution of altruism on Earth, much less among other possible intelligent life forms, to say ETs will all be good,” Dick said. “That is a hope rather than a fact.”

But haven’t we already revealed ourselves with TV signals, military radar and other outputs into the cosmos? Even music is wafting across the universe, purposely directed toward a specific star.

That is true, Dick said, but it’s not the same as sending a directed beam to a habitable exoplanet target.

“Still, the idea of planet Earth cowering and afraid to engage the universe is not a planet I would want to live on. SETI attempts are part of our rising cosmic consciousness, and as such cannot be stifled,” Dick said. “That this is the subject of such controversy…it’s an indication of how seriously the subject of intelligent life in the universe is now taken!”

“But Active SETI is not science,” said Michaud. “It is an attempt to provoke a response from an alien society whose capabilities and intentions are not known to us.”

Those most eager to send high-powered messages want their efforts to have consequences, Michaud said, not just for themselves, but for the entire human species. “There is no scientific or historical evidence telling us that the consequences of contact will be those they prefer." 

Michaud says that an alien society able to detect our signals almost certainly would be more technologically advanced than our own, and might be capable enough and patient enough to send  probes across light-years of space. Scientists and engineers have shown that robotic spacecraft able to reach nearby stars would be feasible for a civilization only slightly in advance of our own.

Michaud takes issue with the old claim that we already have been detected or that detection is inevitable. Experts have shown that the normal signals emitted by Earth are too weak to be heard at interstellar distances without colossal antennas, he said.

"Sending deliberate, unusually powerful signals is a decision that belongs properly with all Humankind,” Michaud said. “We should have an open debate about whether or not to call attention to ourselves by making our civilization more detectable than it already is.”

http://m.space.com/26449-contact-intelligent-aliens-active-seti.html
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Planet OGLE-2013-BLG-0341LBb Orbits in Binary Star System

Although the planet orbits one of the two stars at almost the same distance that the Earth orbits the Sun, that particular star is much dimmer, meaning that the planet itself is probably colder than Jupiter’s moon Europa.

That said, the researchers say the dynamics of the system show that it is possible for the planet to maintain a stable orbit if that parent star was of the same mass and energy as the Sun. If that were the case, the planet could be considered habitable.

“This greatly expands the potential locations to discover habitable planets in the future,” said Scott Gaudi, an astronomer researcher at Ohio State University who participated in the research. “Half the stars in the galaxy are in binary systems. We had no idea if Earth-like planets in Earth-like orbits could even form in these systems.”

(Source: https://www.youtube.com/)
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