Posted on by Jason Major

Hunting for High Life: What Lives in Earth’s Stratosphere?

The Moon photographed through the layers of the atmosphere from the ISS in December 2003 (NASA/JSC)

What lives at the edge of space? Other than high-flying jet aircraft pilots (and the occasional daredevil skydiver) you wouldn’t expect to find many living things over 10 kilometers up — yet this is exactly where one NASA researcher is hunting for evidence of life.

Earth’s stratosphere is not a place you’d typically think of when considering hospitable environments. High, dry, and cold, the stratosphere is the layer just above where most weather occurs, extending from about 10 km to 50 km (6 to 31 miles) above Earth’s surface. Temperatures in the lowest layers average -56 C (-68 F) with jet stream winds blowing at a steady 100 mph. Atmospheric density is less than 10% that found at sea level and oxygen is found in the form of ozone, which shields life on the surface from harmful UV radiation but leaves anything above 32 km openly exposed.

Sounds like a great place to look for life, right? Biologist David Smith of the University of Washington thinks so… he and his team have found “microbes from every major domain” traveling within upper-atmospheric winds.

Smith, principal investigator with Kennedy Space Center’s Microorganisms in the Stratosphere (MIST) project, is working to take a census of life tens of thousands of feet above the ground. Using high-altitude weather balloons and samples gathered from Mt. Bachelor Observatory in central Oregon, Smith aims to find out what kinds of microbes are found high in the atmosphere, how many there are and where they may have come from.

“Life surviving at high altitudes challenges our notion of the biosphere boundary.”

– David Smith, Biologist, University of Washington in Seattle

Although reports of microorganisms existing as high as 77 km have been around since the 1930s, Smith doubts the validity of some of the old data… the microbes could have been brought up by the research vehicles themselves.

“Almost no controls for sterilization are reported in the papers,” he said.

But while some researchers have suggested that the microbes could have come from outer space, Smith thinks they are terrestrial in origin. Most of the microbes discovered so far are bacterial spores — extremely hardy organisms that can form a protective shell around themselves and thus survive the low temperatures, dry conditions and high levels of radiation found in the stratosphere. Dust storms or hurricanes could presumably deliver the bacteria into the atmosphere where they form spores and are transported across the globe.

If they land in a suitable environment they have the ability to reanimate themselves, continuing to survive and multiply.

Although collecting these high-flying organisms is difficult, Smith is confident that this research will show how such basic life can travel long distances and survive even the harshest environments — not only on Earth but possibly on other worlds as well, such as the dessicated soil of  Mars.

“We still have no idea where to draw the altitude boundary of the biosphere,” said Smith. This research will “address how long life can potentially remain in the stratosphere and what sorts of mutations it may inherit while aloft.”

Read more on Michael Schirber’s article for Astrobiology Magazine here, and watch David Smith’s seminar “The High Life: Airborne Microbes on the Edge of Space” held May 2012 at the University of Washington below:

Inset images – Top: layers of the atmosphere, via the Smithsonian/NMNH. Bottom: Scanning electron microscope image of atmospheric bacterial spores collected from Mt. Bachelor Observatory (NASA/KSC)

Posted on by Nancy Atkinson

Mars Sample Return Mission? Naaah… Just Beam Back Martian DNA

Artist concept of a Mars Sample Return mission. Credit: Wickman Spacecraft & Propulsion.

A Mars sample return mission has long been a dream and goal of many planetary scientists. Getting Martian soil samples back here on Earth would allow them to be studied in ways rovers and landers just can’t do. Of course, the big reason for getting samples of Mars back to Earth would be to really determine if there ever was – or is — life on Mars. But a sample return mission would be “hellishly difficult,” Steve Squyres of the MER mission once said.

But forget sending a lander, scooping up samples, putting them in a capsule and somehow rocketing them back to Earth. Human genome sequencer Craig Venter wants to send a DNA sequencing machine Mars, and beam back the DNA data to Earth. Not to be outdone, Jonathan Rothberg, founder the DNA sequencing company Ion Torrent, is working on getting his Personal Genome Machine to Mars and sending back the data.

In articles in the Los Angeles Times and MIT’s Technology Review this week the two biologists seem to be in a race, of sorts, to see who could send their DNA machines to Mars first. Venter was quoted as saying, “There will be life forms there,” Venter said, and wants to build a “biological teleporter.”

Rothberg is looking to be part of a NASA-funded project at Harvard and MIT called SET-G, or “the search for extraterrestrial genomes.”

An MIT researcher involved in the project, Christopher Carr, told Technology Review that his lab is working to shrink Ion Torrent’s machine from 30 kilograms down to just three kilograms so that it can fit on a NASA rover, and they are testing how well the device can withstand the heavy radiation it would encounter on the way to Mars.

With NASA’s current budget woes, a sample return mission likely couldn’t happen until around 2030. But another Mars rover mission may be slated for 2018, if all goes well, and a DNA sequencer could potentially be part of the mission, the two biologists said. And an in-situ DNA sequencer avoids the potential pitfalls of a sample return mission.

“People are worried about the Andromeda strain,” Venter said. “We can rebuild the Martians in a P-4 spacesuit lab instead of having them land in the ocean.”

Sources: Los Angeles Times, Technology Review

Posted on by John Williams

Finding Life in All the Unlikely, Unexpected Places

Just one of several weather stations set up at Chott El Jerid, a Tunisian saltpan, measuring temperature, humidity, ultraviolet radiation, wind direction and velocity. Image credit: Felipe Goméz/Europlanet

From orbit and on the ground, Mars looks inhospitable. But it doesn’t look much different than the freezing Antarctic plains, sun-baked saltpans in Tunisia or Spain’s corrosively acidic Rio Tinto, according to a few explorers from the Centro de Astrobiología (CAB) in Madrid, who today presented some of their findings of life during a press conference at the European Planetary Science Congress.

The biggest difference, however, is that life still thrives in these extreme locales on Earth.

“The big questions are: what is life, how can we define it and what the requirements for supporting life?” asks project leader Dr. Felipe Goméz. “To understand the results we receive back from missions like Curiosity, we need to have detailed knowledge of similar environments on Earth. Metabolic diversity on Earth is huge. We have found a range of complex chemical processes that allow life to survive in unexpected places.”

Over the past four years, Goméz and his colleagues have checked Earth’s most inhospitable locales; the Chott el Jerid saltpan in Tunisia, the Atacama Desert in Chile, Rio Tinto in southern Spain and Deception Island in Antarctica.

While visiting Chott el Jerid, the team tracked huge changes in environmental conditions throughout the day but it was a small rise in surface temperature after dusk that caught their eye. “We found that this is caused by water condensing on the surface and hydrating salts which releases heat in an exothermic reaction,” he said in the press release. This is very interesting from the perspective of the REMS instrument on Curiosity — it gives us away to follow when liquid water might be present on the surface.”

The team also built a three-dimensional picture of the subsurface in the saltpan by measuring the electrical properties of the soil. While drilling several meters into the subsurface at Chott el Jerid and in the Atacama Desert, researchers found bacteria at depth that was completely isolated from the surface. The researchers found not only bacteria, but also single-celled halophilic organisms that are able to oxidize metabolites under both aerobic and anaerobic conditions.

Along the surface of Chott El Jerid, which is made up of very pure sodium chloride with a trace of other salts, the team found small pieces of organic matter within the salt crystals. Once analyzed, they found populations of halophilic, salt-loving, dormant bacteria. In the laboratory, they were able to rehydrate the samples and bring the bacteria back to life, Goméz said.

Another unexpected find occurred while studying outcrops of the mineral jarosite at Rio Tinto in Spain. Jarosite, found on the surface of Mars by the Mars Exploration Rover Opportunity, forms only in the presence of water that contains high concentrations of metals, such as iron. The outcrops at Rio Tinto also are extremely corrosive. Yet, sandwiched between layers in the salt crusts, the team found photosynthetic bacteria. Unexpectedly, iron in the salt crust seems to protect bacteria from ultraviolet radiation, Goméz said. Samples of bacteria with iron present were exposed with high levels of ultraviolet radiation. They survived while bacteria samples without iron were destroyed.

“What the bacteria we found in Rio Tinto show is that the presence of ferric compounds can actually protect life. This could mean that life formed earlier on Earth than we thought. These effects are also relevant for the formation of life on the surface of Mars,” says Goméz. The team also found that salt provides stable conditions that can allow life to survive in very hard environments.

“Within salts, the temperature and humidity are protected from fluctuations and the doses of ultraviolet radiation are very low,” explained Goméz. “In the laboratory, we placed populations of different bacteria between layers of salt a few millimetres thick and exposed them to Martian conditions. Nearly 100% of deinoccocus radiodurans, a hardy type of bacteria survived being irradiated. But fascinatingly, about 40% of acidithiobacillus ferrooxidans – a very fragile variety of bacteria – also survived when protected by a salt crust.”

The findings have implications not only for studying possible life on Mars, but also for the development of life on early Earth.

Source: European Planetary Science Congress (EPSC) 2012 Press Release

Image Details: Photosynthetic bacteria at Rio Tinto. Credit: Felipe Goméz

About the author: John Williams is owner of TerraZoom, a Colorado-based web development shop specializing in web mapping and online image zooms. He also writes the award-winning blog, StarryCritters, an interactive site devoted to looking at images from NASA’s Great Observatories and other sources in a different way. A former contributing editor for Final Frontier, his work has appeared in the Planetary Society Blog, Air & Space Smithsonian, Astronomy, Earth, MX Developer’s Journal, The Kansas City Star and many other newspapers and magazines. Follow John on Twitter @terrazoom

Posted on by Jason Major

Flashback: 1978 NASA Film Shows Viking Discoveries

In what’s a sort of foreshadowing of the upcoming August 5 MSL landing, which is being called “seven minutes of terror”, here’s a flashback film from 1978 called “19 Minutes to Earth” which looks at the discoveries made by the Viking orbiter and lander, which made its historic arrival on Mars 36 years ago, on July 20, 1976.

In true late ’70s style the video is full of funky music and (what was then) state-of-the-art video graphics. Awesome.


Even more than the music, though, what’s interesting about the 1978 film is how the subject of microbial life is discussed. Both Viking 1 and 2 were designed to search for evidence of biological activity on Mars, which they did by digging into the Martian soil and looking for signs of resulting respiration.

Although the results were initially deemed inconclusive, further research into the Viking data has prompted some scientists to claim that the landers did, in fact, find evidence of life on Mars.

It’s still a much-debated topic, one that scientists hope to help settle with the upcoming research performed by Curiosity and the Mars Science Laboratory mission.

Funky music and all, the Viking programs paved the way for all future missions to Mars. Lessons learned from Viking technology have blazed the trail for Mars research, from Pathfinder’s Sojourner rover to Spirit and Opportunity, the Mars Reconnaissance Orbiter and ESA’s Mars Express. Very soon Curiosity will continue on with the legacy of robotic exploration of the Red Planet, and someday I’m sure our children and grandchildren will look back at the “funky videos” of our time.

Let’s hope that by then they’ve made their own great strides in space exploration and have found answers to the questions that inspire us today.

Video: NASA. Image: artist’s concept of the Viking lander (NASA).

Posted on by Ken Kremer

Dawn’s Vestan Endeavour Exceptionally Exciting near End of Year-Long Super Science Survey

Image Caption: Divalia Fossa equatorial trough at Vesta pictured in side by side images showing apparent brightness and topography. The trough encircles most of Vesta and is located just south of the equator. It is about 10 kilometers (6 miles) wide. Rubria and Occia craters straddle Divalia Fossa. The image was snapped on Oct 16, 2011 from an altitude of 700 km (435 mi) from the HAMO mapping orbit. Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA

“NASA’s Dawn mission to Asteroid Vesta is going exceptionally well”, Dr. Marc Rayman, the mission’s Chief Engineer, told Universe Today in an exclusive interview as the revolutionary spacecraft nears the end of its more than 1 year long super science survey orbiting the giant space rock.

“The Dawn mission is not only going better than we had expected but even better than we had hoped.”

Dawn is Earth’s first mission ever to orbit and explore Vesta up close.

“We have acquired so much more data than we had planned even in late 2011! We have conducted a tremendous exploration of Vesta – the second most massive body between Mars and Jupiter, a giant of the main asteroid belt.”

“Now we are in our second high altitude mapping orbit (HAMO2), which is the final intensive campaign of the Vesta mission,” Rayman told me.

Image Caption: Dawn Orbiting Vesta above the “Snowman” craters. This artist’s concept shows NASA’s Dawn spacecraft orbiting the giant asteroid Vesta above the Snowman craters. The depiction of Vesta is based on images obtained by Dawn’s framing cameras. Dawn is an international collaboration of the US, Germany and Italy. Credit: NASA/JPL-Caltech

Indeed Dawn’s science and maneuvering endeavour’s at Vesta have proceeded so flawlessly that NASA has granted the science team a bonus of 40 days additional time in orbit split between the lower and higher science orbits known as LAMO and HAMO or the Low Altitude Mapping Orbit and the High Altitude Mapping Orbit respectively.

“Our original Vesta departure date was July 17, and now it is about August 26.” Rayman explained.

The bonus time at LAMO has already been completed. Now the team is about to begin the bonus time at HAMO – consisting of two additional mapping cycles beyond the four originally planned.

Each mapping cycle in HAMO2 consists of 10 orbits. Each orbit is about 12.5 hours.

“On July 14, we will complete mapping cycle 4 and begin 5 (of 6). On July 25 we will leave HAMO2 and escape from orbit on August 26. We will stop thrusting several times before escape to take more neat pictures, mostly of the northern hemisphere,” Rayman told me.

“As Dawn revolves, Vesta rotates on its axis beneath it, turning once every 5.3 hours.”

When Dawn arrived in orbit at Vesta in July 2011 the northern polar region was in darkness as the southern hemisphere basked in summer’s glow. Now as Dawn departs Vesta in August, virtually all of the previously unseen and unphotographed northern polar region is illuminated and will be mapped in exquisite detail.

Coincidentally on July 13/14 as HAMO2 Cycle 4 ends, I’ll be presenting a free public lecture about Dawn and NASA’s Planetary and Human Spaceflight programs at the Adirondack Public Observatory.

Image Caption: Asteroid Vesta and Mysterious Equatorial Grooves – from Dawn Orbiter. This full view of the giant asteroid Vesta was taken by NASA’s Dawn spacecraft on July 24, 2011, at a distance of 3,200 miles (5,200 kilometers). This view shows impact craters of various sizes and mysterious grooves parallel to the equator. The resolution of this image is about 500 meters per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Why has Dawn been granted an extended mission ?

“Dawn has gone so well that we had consumed not even one day of our 40 days of operations margin,” Rayman stated .

“That allowed us to spend more time in LAMO. We had had some unexpected events to be sure, but we managed to deal with all of them so expeditiously that the entire margin remained intact. Then we received the (entirely unrelated) 40 day extension, which allowed us to leave Vesta later. That came about because of our being able to shorten the flight from Vesta to Ceres, so we could still reach Ceres on schedule in 2015.”

“That 40 days allowed us to spend still ~ 30 more days in LAMO and increase HAMO2 by 10 days to a total of six cycles. We got still more time by finding ways to make the trip from HAMO2 to escape a little more efficiently, and that’s what allowed HAMO2 to be even longer, with the additional eight days of VIR-only observations I described in my most recent Dawn Journal.”

“The summary is that every investigation has been more productive than we could have imagined, and because the exploration of Vesta has gone so well, we have been able to apply our unused margin to get even more out of the mission. It is very very gratifying and exciting.”

So we have a few more weeks to enjoy the wondrous sights of Vesta before Dawn fires up her revolutionary ion thrusters to escape the gravitational tug of Vesta and head off to the dwarf planet Ceres, the largest asteroid in the main belt of our Solar System – and which some have speculated may hold vast caches of water and perhaps even liquid oceans suitable for sustaining life.

Ken Kremer

…..
July 13/14: Free Public Lectures about NASA’s Mars, Vesta and Planetary Exploration, the Space Shuttle, SpaceX , Orion and more by Ken Kremer at the Adirondack Public Observatory in Tupper Lake, NY.

Posted on by Jenny Winder

Curiosity and the Issue of Planetary Protection

Curiosity at Centre of Attention During Testing Image Credit: NASA /JPL - Caltech

Curiosity at Centre of Attention During Testing Image Credit: NASA /JPL – Caltech

There have been many reports about the possibility of NASA’s Curiosity rover contaminating Mars with microbes from Earth once it lands on the Red Planet in August. The wheels, the landing procedure and the drill bits have all come under scrutiny. But what are the concerns and what safeguards are there to prevent contamination from this or other missions?

In 1967 the United Nations drew up the ‘Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Bodies.’ All countries which sign up to the treaty “shall pursue studies of outer space, including the moon and other celestial bodies, and conduct exploration of them so as to avoid their harmful contamination.” Every mission is given a category (I,II,III,IV or V) depending on whether it is a flyby, orbiter, lander, or Earth return mission, whether its destination is a planet, moon, comet, or asteroid and whether the destination could provide clues about life or have the potential to support Earth life. So for instance Cassini is a catagory II mission, Curiosity is classed as a IVc mission.

Every stage of a mission is carefully monitored. From construction in a sterile clean room with laminar-air-flow systems, pressurized microbial barriers and personnel wearing hoods, masks, surgical gloves, booties and protective suits called bunny suits. Components and entire spacecraft are sterilized using dry heat microbial reduction, by being enclosed in a bioshield (like a large casserole dish) and baked them in an oven at 111.7 degrees Celsius for 30 hours. For more sensitive components a low-temperature process is used. Components are placed in a vacuum and hydrogen peroxide is injected into the sterilization chamber to establish a specified vapor concentration. Thousands of samples are taken at every stage of construction and tested for spore-forming organisms, for example the Viking mission in 1975 tested more than 6000 samples in total.

Three issues have arisen with the Curiosity rover. During the landing procedure a parachute and thrusters will slow the descent before the ‘sky crane’ lowers the rover, its wheels making direct contact with the surface. Previous rovers have waited on landing platforms for days before their wheels made contact with the surface and in tests it has been shown that even a few hours exposure to Martian levels of ultraviolet can kill between 81 and 96 per cent of bacteria that may be present. So once Curiosity lands it will probably need to remain stationary for some days to minimize the risk of contamination from its wheels.

Another issue arose last year, after launch, when it was realized that a step in the planetary protection measures wasn’t adhered to during the manufacture of the rover’s drill bits. These were meant to arrive at Mars inside a sterile box, but the box was opened and the bits tested for contamination and one of the bits was attached to the drill head. This procedure strayed from earlier agreed-to protocols. The drills have now become another cause concern as it has been found that Teflon and molybdenum disulfide from seals within the drill assembly could rub off and mix in to contaminate samples excavated during operation, making the samples more difficult to analyze. The MSL team are looking at ways to work around the problem, these could include running the drill on a slower, less percussive setting or dispensing with the drill altogether and relying on Curiosity’s scoop to take soils soil samples and using the rover’s wheels to roll over and break open rocks.

This all serves to highlight the importance of the planetary protection treaty to ensure we do everything possible to reduce the risk of contaminating other worlds and of compromising any data we return.

Find out more at NASA’s Office of Planetary Protection

Posted on by Jason Major

Aliens Don’t Want To Eat Us, Says Former SETI Director

Don't worry Ridley, she just wants to explore.

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Alien life probably isn’t interested in having us for dinner, enslaving us or laying eggs in our bellies, according to a recent statement by former SETI director Jill Tarter.

(Of course, Hollywood would rather have us think otherwise.)

In a press release announcing the Institute’s science and sci-fi SETIcon event, taking place June 22 – 24 in Santa Clara, CA, Tarter — who was the inspiration for Jodie Foster’s character in the film “Contact” — disagreed with both filmmakers and Stephen Hawking over the portrayal of extraterrestrials as monsters hungry for human flesh.

“Often the aliens of science fiction say more about us than they do about themselves,” Tarter said. “While Sir Stephen Hawking warned that alien life might try to conquer or colonize Earth, I respectfully disagree. If aliens were able to visit Earth that would mean they would have technological capabilities sophisticated enough not to need slaves, food, or other planets. If aliens were to come here it would be simply to explore.

“Considering the age of the universe, we probably wouldn’t be their first extraterrestrial encounter, either. We should look at movies like ‘Men in Black III,’ ‘Prometheus’ and ‘Battleship’ as great entertainment and metaphors for our own fears, but we should not consider them harbingers of alien visitation.”

SETI's Alien Telescope Array (ATA) listens day and night for a signal from space (SETI)

Tarter, 68, recently announced her stepping down as director of SETI in order to focus on funding for the Institute, which is currently running only on private donations. Funding SETI, according to Tarter, is investing in humanity’s future.

“Think about it. If we detect a signal, we could learn about their past (because of the time their signal took to reach us) and the possibility of our future. Successful detection means that, on average, technologies last for a long time. Understanding that it is possible to find solutions to our terrestrial problems and to become a very old civilization, because someone else has managed to do just that, is hugely important! Knowing that there can be a future may motivate us to achieve it.”

On the other hand, concern that searching the sky for signs of life — as well as sending out your own — could call down hungry alien monsters would make a good case for keeping quiet. And a quiet search may not get the necessary funding to keep going. I can see where Tarter is coming from.

Let’s just hope she’s right. (About the eating part, at least.)

Top image: Alien 3, © 20th Century Fox. Tip of the tinfoil hat to EarthSky.org. 

Posted on by Jason Major

Is Earth Alive? Scientists Seek Sulfur For An Answer

Image of Earth taken by ESA's Rosetta spacecraft in 2009

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Researchers at the University of Maryland have discovered a way to identify and track sulfuric compounds in Earth’s marine environment, opening a path to either refute or support a decades-old hypothesis that our planet can be compared to a singular, self-regulating, living organism — a.k.a. the Gaia theory.

Proposed by scientists James Lovelock and Lynn Margulis in the 70s, the Gaia theory likens Earth to a self-supporting singular life form, similar to a cell. The theory claims that, rather than being merely a stage upon which life exists, life — in all forms — works to actively construct an Earthly environment in which it can thrive.

Although named after the Greek goddess of Earth, the Gaia theory is not so much about mythology or New Age mysticism as it is about biology, chemistry and geology — and how they all interact to make our world suitable for living things.

Once called the Gaia hypothesis, enough scientific cross-disciplinary support has since been discovered that it’s now commonly referred to as a theory.

Marine phytoplankton -- like these diatoms -- may produce sulfur compounds that can be transmitted into the air, affecting climate. (NOAA image)

One facet of the Gaia theory is that sulfur compounds would be created by microscopic marine organisms — such as phytoplankton and algae — and these compounds could be transmitted into the air, and eventually (in some form) to the land, thus helping to support a sulfur cycle.

Sulfur is a key element in both organic and inorganic compounds. The tenth most abundant element in the Universe, sulfur is crucial to climate regulation — as well as life as we know it.

In particular, two sulfur compounds — dimethylsulfoniopropionate and its atmospherically-oxidized version, dimethylsulfide — are considered to be likely candidates for the products created by marine life. It’s these two compounds that UMD researcher Harry Oduro, along with geochemist and professor James Farquhar and marine biologist Kathryn Van Alstyne (of Western Washington University) have discovered a way to track across multiple environments, from sea to air to land, allowing scientists to trace which isotopes are coming from what sources.

“What Harry did in this research was to devise a way to isolate and measure the sulfur isotopic composition of these two sulfur compounds,” said Farquhar. “This was a very difficult measurement to do right, and his measurements revealed an unexpected variability in an isotopic signal that appears to be related to the way the sulfur is metabolized.”

The team’s research can be used to measure how the organisms are producing the compounds, under which circumstances and how they are ultimately affecting their — and our — environment in the process.

“The ability to do this could help us answer important climate questions, and ultimately better predict climate changes,” said Farquhar. “And it may even help us to better trace connections between dimethylsulfide emissions and sulfate aerosols, ultimately testing a coupling in the Gaia hypothesis.”

Whether or not Earth can be called a singular — or possibly even sentient — living organism of which all organisms are contributing members thereof may still be up for debate, but it is fairly well-accepted that life can shape and alter its own environment (and in the case of humans, often for the worse.) Research like this can help science determine just how far-reaching those alterations may be.

The study appears in this week’s Online Early Edition of the Proceedings of the National Academy of Sciences (PNAS).

Read more on the University of Maryland’s news page here.

Image credit: ESA ©2009 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA. Edited by J. Major.

Posted on by Jason Major

Rogue Planets Could Drive By And Scoop Up Life

Artist's rendering of an Earth-sized rogue planet approaching a star. Credit: Christine Pulliam (CfA)

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Free-floating “rogue” planets may occasionally dip into the inner Solar System, picking up dust containing organic compounds — a.k.a. the ingredients for life — and carry it back out into the galaxy, according to new research by Professor Chandra Wickramasinghe, Director of the University of Buckingham Centre for Astrobiology in the UK.

Rogue planets are thus called because they are not in orbit around a star. Either forcibly ejected from a solar system or having formed very early on in the Universe — even within a few million years after the Big Bang, the team proposes — these vagrant worlds may vastly outnumber stars. In fact, it’s been suggested there are as much as 100,000 times more rogue planets than stars in our Milky Way galaxy alone!

Read: Rogue Planets Can Find Homes Around Other Stars

Professor Wickramasinghe — a proponent of the panspermia hypothesis whereby the ingredients for life can be transported throughout the galaxy on dust, comets, and perhaps even planets — and his team have suggested in a paper published in the journal Astrophysics and Space Science that Earth-sized rogue planets could pass through the inner Solar System, possibly as often as once every 25 million years on average. Like a cosmic drive-thru these planets could gather zodiacal dust from the plane of the Solar System during their pass, thus picking up organic compounds along the way.

The planets would then take the material gathered from one solar system and possibly bring it into another, serving as a type of interstellar cross-pollinator.

Wickramasinghe’s team propose that, by this process, there could be more life-bearing, Earth-sized planets existing between the stars than orbiting around them — a lot more. Based on their estimates there may be as much as a few hundred thousand billion such worlds in our galaxy… that’s several thousand for every star.

It will be interesting to see how this idea is received, but it definitely is an intriguing concept. As we hunt for the “Holy Grail” of life-friendly exoplanets around other stars, they may be drifting through the darkness in number, hiding in the spaces between.

Posted on by Jason Major

Alien Life May Not Be So Alien – If It Exists At All

Our galaxy has exoplanets, organic compounds, liquid water -- even a nebula shaped like a DNA helix -- but is there life? (Image credit: M. Morris/UCLA)

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Are we too hopeful in our hunt for extraterrestrial life? Regardless of exoplanet counts, super-Earths and Goldilocks zones, the probability of life elsewhere in the Universe is still a moot point — to date, we still only know of one instance of it. But even if life does exist somehow, somewhere besides Earth, would it really be all that alien?

In a recent paper titled “Bit by Bit: the Darwinian Basis for Life” Gerald Joyce, Professor of Molecular Biology and Biochemistry at the Scripps Research Institute in La Jolla, CA discusses the nature of life as we know it in regards to its fundamental chemical building blocks — DNA, RNA — and how its ability to pass on the memory of its construction separates true biology from mere chemistry.

“Evolution is nothing more than chemistry plus history,” Joyce said during a Public Library of Science podcast.

The DNA structures that evolved here on Earth — the only place in the Universe we know for certain that life can thrive — have proven to be highly successful (obviously). So what’s to say that life elsewhere wouldn’t be based on the same basic building blocks? And if it is, is it really a “new” life form?

“Truly new ‘alternative life’ would be life of a different biology,” Joyce said. “It would not have the information in it that is part of the same heritage of our life form.”

To arise in the first place, according to Joyce, new life can take two possible routes. Either it begins as chemical connections that grow increasingly more complex until they begin to hold on to the memory of their specific “bit” structure, eventually “bit-flipping” — aka, mutating — into new structures that are either successful or unsuccessful, or it starts from a more “privileged” beginning as an offshoot of previous life, bringing bits into a totally new, immediately successful orientation.

With those two scenarios, anywhere besides Earth “there are no example of either of those conditions so far.”

That’s not saying that there’s no life elsewhere in the Universe… just that we have yet to identify any evidence of it. And without evidence, any discussion of its probability is still pure conjecture.

“In order to estimate probabilities, we need facts,” said Joyce. “The problem is, there is only one life form. And so it’s not possible to estimate probability of life elsewhere when you have only one example.”

Voyager included a golden record with images and sounds of Earthly life recorded on it... just in case. (NASA)

Even though exoplanets are being found on a nearly daily basis, and it’s only a matter of time before a rocky, Earthlike world with liquid water on its surface is confirmed orbiting another star, that’s no guarantee of the presence of alien life — despite what conclusions the headlines will surely jump to.

There could be a billion habitable planets in our galaxy. But what’s the relationship between habitable and inhabited?” Joyce asks. “We don’t know.”

Still, we will continue to search for life beyond our planet, be it truly alien in nature… or something slightly more familiar. Why?

“I think humans are lonely,” Joyce said. “I think humans are like Geppetto — we want to have a ‘real boy’ out there that we can point to, we want to find a Pinocchio living on some extrasolar planet… and then somehow we won’t be such a lonely life form.”

And who knows… if any aliens out there really are a lot like us, they may naturally be searching for evidence of our existence as well. If only to not be so lonely.

Listen to the full PLoS podcast here.