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Prepare For Lift-off! BepiColombo Launches For Mercury

Artist illustration of the BepiColombo orbiters, MIO and Bepi, around Mercury (JAXA).

This Friday (October 19) at 10:45pm local time in French Guinea, a spacecraft is set to launch for Mercury. This is the BepiColombo mission which will begin its seven year journey to our solar system’s innermost planet. Surprisingly, the science goals for investigating this boiling hot world are intimately linked to habitability.

Mercury orbits the sun at an average distance of 35 million miles (57 million km); just 39% of the distance between the sun and the Earth. The planet therefore completes a year in just 88 Earth days.

The close proximity to the sun puts Mercury in a 3:2 tidal lock, meaning the planet rotates three times for every two orbits around the sun. (By contrast, our moon is in a 1:1 tidal lock and rotates once for every orbit around the Earth.) With only a tenuous atmosphere to redistribute heat, this orbit results in extreme temperatures between about -290°F and 800°F (-180°C to 427°C). The overall picture is one of the most inhospitable of worlds, so what do we hope to learn from this barren and baked land?

BepiColombo is a joint mission between the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA). It consists of two orbiters, one built by each space agency. The mission is named after Giuseppe “Bepi” Colombo, an Italian mathematician who calculated the orbit of the first mission to Mercury —NASA’s Mariner 10— such that it could make repeated fly-bys of the planet.

When Mariner 10 reached Mercury in the mid-1970s, it made an astonishing discovery:  the planet had a weak magnetic field. The Earth also has a magnetic field that is driven by movement in its molten iron core.

However, with a mass of only 5.5% that of the Earth, the interior of Mercury was expected to have cooled sufficiently since its formation for the core to have solidified and jammed the breaks on magnetic field generation. This is thought to have happened to Mars, which is significantly larger than Mercury with a mass around 10% that of the Earth. So how does Mercury hold onto its field?

The discoveries only got stranger with the arrival of NASA’s MESSENGER mission in 2011. MESSENGER discovery that Mercury’s magnetic field was off-set, with the center shifted northwards by a distance equal to 20% of the planet’s radius.

The mysteries also do not end with Mercury’s wonky magnetic field.… Read more

Technosignatures and the Search for Extraterrestrial Intelligence

A rendering of a potential Dyson sphere, named after Freeman A. Dyson. As proposed by the physicist and astronomer decades ago, they would collect solar energy on a solar system wide scale for highly advanced civilizations. (SentientDevelopments.com)

The word “SETI” pretty much brings to mind the search for radio signals come from distant planets, the movie “Contact,” Jill Tarter, Frank Drake and perhaps the SETI Institute, where the effort lives and breathes.

But there was a time when SETI — the Search for Extraterrestrial Intelligence — was a significantly broader concept, that brought in other ways to look for intelligent life beyond Earth.

In the late 1950s and early 1960s — a time of great interest in UFOs, flying saucers and the like — scientists not only came up with the idea of searching for distant intelligent life via unnatural radio signals, but also by looking for signs of unexpectedly elevated heat signatures and for optical anomalies in the night sky.

The history of this search has seen many sharp turns, with radio SETI at one time embraced by NASA, subsequently de-funded because of congressional opposition, and then developed into a privately and philanthropically funded project of rigor and breadth at the SETI Institute.  The other modes of SETI went pretty much underground and SETI became synonymous with radio searches for ET life.

But this history may be about to take another sharp turn as some in Congress and NASA have become increasingly interested in what are now called “technosignatures,” potentially detectable signatures and signals of the presence of distant advanced civilizations.  Technosignatures are a subset of the larger and far more mature search for biosignatures — evidence of microbial or other primitive life that might exist on some of the billions of exoplanets we now know exist.

And as a sign of this renewed interest, a technosignatures conference was scheduled by NASA at the request of Congress (and especially retiring Republican Rep. Lamar Smith of Texas.)  The conference took place in Houston late last month, and it was most interesting in terms of the new and increasingly sophisticated ideas being explored by scientists involved with broad-based SETI.

“There has been no SETI conference this big and this good in a very long time,” said Jason Wright, an astrophysicist and professor at Pennsylvania State University and chair of the conference’s science organizing committee.  “We’re trying to rebuild the larger SETI community, and this was a good start.”

 

At this point, the search for technosignatures is often likened to that looking for a needle in a haystack.

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Human Space Travel, Health and Risk

Astronauts in a mock-up of the Orion space capsule, which NASA plans to use in some form as a deep-space vehicle. (NASA)

 

We all know that human space travel is risky. Always has been and always will be.

Imagine, for a second, that you’re an astronaut about to be sent on a journey to Mars and back, and you’re in a capsule on top of NASA’s second-generation Space Launch System designed for that task.

You will be 384 feet in the air waiting to launch (as tall as a 38-floor building,) the rocket system will weigh 6.5 million pounds (equivalent to almost nine fully-loaded 747 jets) and you will take off with 9.2 million pounds of thrust (34 times the total thrust of one of those 747s.)

Given the thrill and power of such a launch and later descent, everything else seemed to pale in terms of both drama and riskiness.  But as NASA has been learning more and more, the risks continue in space and perhaps even increase.

We’re not talking here about a leak or a malfunction computer system; we’re talking about absolutely inevitable risks from cosmic rays and radiation generally — as well as from micro-gravity — during a long journey in space.

Since no human has been in deep space for more than a short time, the task of understanding those health risks is very tricky and utterly dependent on testing creatures other than humans.

The most recent results are sobering.  A NASA-sponsored team at Georgetown University Medical Center in Washington looked specifically at what could happen to a human digestive system on a long Martian venture, and the results were not reassuring.

Their results, published in the Proceedings of the National Academy of Sciences  (PNAS), suggests that deep space bombardment by galactic cosmic radiation and solar particles could significantly damage gastrointestinal tissue leading to long-term functional changes and problems. The study also raises concern about high risk of tumor development in the stomach and colon.

 

Galactic cosmic rays are a variable shower of charged particles coming from supernova explosions and other events extremely far from our solar system. The sun is the other main source of energetic particles this investigation detects and characterizes. The sun spews electrons, protons and heavier ions in “solar particle events” fed by solar flares and ejections of matter from the sun’s corona. Magnetic fields around Earth protect the planet from most of these heavy particles, but astronauts do not have that protect beyond low-Earth orbit.

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Time-Traveling in the Australian Outback in Search of Early Earth

This story was written by Nicholas Siegler, Chief Technologist for NASA’s Exoplanet Exploration Program at the Jet Propulsion Laboratory with the help of doctoral student Markus Gogouvitis, at the University of New South Wales, Australia and Georg-August-University in Gottingen, Germany.

 

These living stromatolites at Shark Bay, Australia are descendants of similar microbial/sedimentary forms once common around the world.  They are among the oldest known repositories of life.  Most stromatolites died off long ago, but remain at Shark Bay because of the high salinity of the water. (Tourism, Western Australia)

 

This past July I joined a group of geologists, geochemists, microbiologists, and fellow astronomers on a tour of some of the best-preserved evidence for early life.

Entitled the Astrobiology Grand Tour, it was a trip led by Dr. Martin Van Kranendonk, a structural geologist from the University of New South Wales, who had spent more than 25 years surveying Australia’s Pilbara region. Along with his graduate students he had organized a ten-day excursion deep into the outback of Western Australia to visit some of astrobiology’s most renowned sites.

The trip would entail long, hot days of hiking through unmaintained trails on loose surface rocks covered by barb-like bushes called spinifex.  As I was to find out, nature was not going to give up its secrets easily.  And there were no special privileges allocated to astrophysicists from New Jersey.

 

The route of our journey back in time.  (Google Earth/Markus Gogouvitis /Martin Van Kranendonk)

The state of Western Australia, almost four times the size of the American state of Texas but with less than a tenth of the population (2.6 million), is the site of many of astrobiology’s most heralded sites. For more than three billion years, it has been one of the most stable geologic regions in the world.

It has been ideal for geological preservation due to its arid conditions, lack of tectonic movement, and remoteness. The rock records have in many places survived and are now able to tell their stories (to those who know how to listen).

 

The classic red rocks of the Pilbara in Western Australia, with the needle sharp spinifex bushes in the foreground. (Nick Siegler, NASA/JPL-Caltech)

Our trip began with what felt like a pilgrimage. We left Western Australia’s largest city Perth and headed north for Shark bsy. It felt a bit like a pilgrimage because the next morning we visited one of modern astrobiology’s highlights – the living stromatolites of Shark Bay.… Read more

Water Worlds, Aquaplanets and Habitability

This artist rendering may show a water world — without any land — or an aquaplanet with lots of more shallow water around a rocky planet. (NASA)

 

The more exoplanet scientists learn about the billions and billions of celestial bodies out there, the more the question of unusual planets — those with characteristics quite different from those in our solar system — has come into play.

Hot Jupiters, super-Earths, planets orbiting much smaller red dwarf stars — they are all grist for the exoplanet mill, for scientists trying to understand the planetary world that has exploded with possibilities and puzzles over the past two decades.

Another important category of planets unlike those we know are the loosely called “water worlds” (with very deep oceans) and their “aquaplanet” cousins (with a covering of water and continents) but orbiting stars very much unlike our sun.

Two recent papers address the central question of habitability in terms of these kind of planets — one with oceans and ice hundreds of miles deep, and one particular and compelling planet (Proxima Centauri b, the exoplanet closest to us) hypothesized to have water on its surface as it orbits a red dwarf star.

The question the papers address is whether these watery worlds might be habitable.  The conclusions are based on modelling rather than observations, and they are both compelling and surprising.

In both cases — a planet with liquid H20 and ice many miles down, and another that probably faces its red dwarf sun all or most of the time — the answers from modelers is that yes, the planets could be habitable.   That is very different from saying they are or even might be inhabited.  Rather,  the conclusions are based on computer models that take into account myriad conditions and come out with simulations about what kind of planets they might be.

This finding of potential watery-world habitability is no small matter because predictions of how planets form point to an abundance of water and ice in the planetesimals that grow into planets.

As described by Eric Ford, co-author of one of the papers and a professor of astrophysics at Pennsylvania State University, “Many scientists anticipate that planets with oceans much deeper than Earths could be a common outcome of planet formation. Indeed, one of the puzzling properties of Earth is that it has oceans that are just skin deep” compared to the radius of the planet.… Read more

Curiosity Rover Looks Around Full Circle And Sees A Once Habitable World Through The Dust

An annotated 360-degree view from the Curiosity mast camera.  Dust remaining from an enormous recent storm can be seen on the platform and in the sky.  And holes in the tires speak of the rough terrain Curiosity has traveled, but now avoids whenever possible. Make the screen bigger for best results and enjoy the show. (NASA/JPL-Caltech/MSSS)

 

When it comes to the search for life beyond Earth, I think it would be hard to point to a body more captivating, and certainly more studied, than Mars.

The Curiosity rover team concluded fairly early in its six-year mission on the planet that “habitable” conditions existed on early Mars.  That finding came from the indisputable presence of substantial amounts of liquid water three-billion-plus years ago, of oxidizing and reducing molecules that could provide energy for simple life, of organic compounds and of an atmosphere that was thick enough to block some of the most harmful incoming cosmic rays.

Last year, Curiosity scientists estimated that the window for a habitable Mars was some 700 million years, from 3.8 to 3.1 billion years ago.  Is it a coincidence that the earliest confirmed life on Earth appeared about 3.8 billion years ago?

Today’s frigid Mars, which has an atmosphere much thinner than in the planet’s early days, hardly looks inviting, although some scientists do see a possibility that primitive life survives below the surface.

But because it doesn’t look inviting now doesn’t mean the signs of a very different planet aren’t visible and detectable through instruments.  The Curiosity mission has proven this once and for all.

The just released and compelling 360-degree look (above) at the area including Vera Rubin Ridge brings the message home.

Those fractured, flat rocks are mudstone, formed when Gale Crater was home to Gale Lake.  Mudstone and other sedimentary formations have been visible (and sometimes drilled) along a fair amount of the 12.26-mile path that Curiosity has traveled since touchdown.

 

An image of Vera Rubin Ridge in traditional Curiosity color, and the same view below with filters designed to detect hematite, or iron oxide. That compound can only be formed in the presence of water. (NASA/JPL-Caltech)

 

The area the rover is now exploring contains enough hematite — iron oxide — that its signal was detectable from far above the planet, making this area a prized destination since well before the Mars Science Laboratory and Curiosity were launched.

Like Martian clays and sulfates that have been identified and explored, the hematite is of great interest because of its origins in water. … Read more

A National Strategy for Finding and Understanding Exoplanets (and Possibly Extraterrestrial Life)

The National Academies of Science, Engineering and Medicine took an in-depth look at what NASA, the astronomy community and the nation need to grow the burgeoning science of exoplanets — planets outside our solar system that orbit a star. (NAS)

 

An extensive, congressionally-directed study of what NASA needs to effectively learn how exoplanets form and whether some may support life was released today, and it calls for major investments in next-generation space and ground telescopes.  It also calls for the adoption of an increasingly multidisciplinary approach for addressing the innumerable questions that remain unanswered.

While the recommendations were many, the top line calls were for a sophisticated new space-based telescope for the 2030s that could directly image exoplanets, for approval and funding of the long-delayed and debated WFIRST space telescope, and for the National Science Foundation and to help fund two of the very large ground-based telescopes now under development.

The study of exoplanets has seen remarkable discoveries in the past two decades.  But the in-depth study from the private, non-profit National Academies of Sciences, Engineering and Medicine concludes that there is much more that we don’t understand than that we do, that our understandings are “substantially incomplete.”

So the two overarching goals for future exoplanet science are described as these:

 

  • To understand the formation and evolution of planetary systems as products of star formation and characterize the diversity of their architectures, composition, and environments.
  • To learn enough about exoplanets to identify potentially habitable environments and search for scientific evidence of life on worlds orbiting other stars.

 

Given the challenge, significance and complexity of these science goals, it’s no wonder that young researchers are flocking to the many fields included in exoplanet science.  And reflecting that, it is perhaps no surprise that the NAS survey of key scientific questions, goals, techniques, instruments and opportunities runs over 200 pages. (A webcast of a 1:00 pm NAS talk on the report can be accessed here.)

 


Artist’s concept showing a young sun-like star surrounded by a planet-forming disk of gas and dust.
(NASA/JPL-Caltech/T. Pyle)

These ambitious goals and recommendations will now be forwarded to the arm of the National Academies putting together 2020 Astronomy and Astrophysics Decadal Survey — a community-informed blueprint of priorities that NASA usually follows.

This priority-setting is probably most crucial for the two exoplanet direct imaging missions now being studied as possible Great Observatories for the 2030s — the paradigm-changing space telescopes NASA has launched almost every decade since the 1970s.

Read more

15,000 Galaxies in One Image

Astronomers have just assembled one of the most comprehensive portraits yet of the universe’s evolutionary history, based on a broad spectrum of observations by the Hubble Space Telescope and other space and ground-based telescopes.  Each of the approximately 15,000 specks and spirals are galaxies, widely distributed in time and space. (NASA, ESA, P. Oesch of the University of Geneva, and M. Montes of the University of New South Wales)

Here’s an image to fire your imagination: Fifteen thousand galaxies in one picture — sources of light detectable today that were generated as much as 11 billion years ago.

Of those 15,000 galaxies, some 12,000 are inferred to be in the process of forming stars.  That’s hardly surprising because the period around 11 billions years ago has been determined to be the prime star-forming period in the history of the universe.  That means for the oldest galaxies in the image, we’re seeing light that left its galaxy but three billion years after the Big Bang.

This photo mosaic, put together from images taken by the Hubble Space Telescope and other space and ground-based telescopes, does not capture the earliest galaxies detected. That designation belongs to a galaxy found in 2016 that was 420 million years old at the time it sent out the photons just collected. (Photo below.)

Nor is it quite as visually dramatic as the iconic Ultra Deep Field image produced by NASA in 2014. (Photo below as well.)

But this image is one of the most comprehensive yet of the history of the evolution of the universe, presenting galaxy light coming to us over a timeline up to those 11 billion years.  The image was released last week by NASA and supports an earlier paper in The Astrophysical Journal by Pascal Oesch of Geneva University and a large team of others.

And it shows, yet again, the incomprehensible vastness of the forest in which we are a tiny leaf.

Some people apparently find our physical insignificance in the universe to be unsettling.  I find it mind-opening and thrilling — that we now have the capability to not only speculate about our place in this enormity, but to begin to understand it as well.

The Ultra-Deep field composite, which contains approximately 10,000 galaxies.  The images were collected over a nine-year period.  {NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z.

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Piecing Together The Narrative of Evolution

A reconstruction of the frond-like sea creature Stromatoveris psygmoglena, which lived during the Cambrian explosion of life forms on Earth.  Newfound fossils of Stromatoveris were compared with Ediacaran fossils, and researchers concluded they were all very early animals and that this animal group survived the mass extinction event that occurred between the Ediacaran and Cambrian periods. (Jennifer Hoyal Cuthill.)

An essential characteristic of life is that it evolves. Whether on Earth or potentially Mars, Europa or distant exoplanets, we can assume that whatever life might be present has the capacity and the need to change.

Evolution is intimately tied to the origin-of-life question, which this column often explores.  Having more answers regarding how life might have started on Earth can no doubt help the search for life elsewhere, just as finding life elsewhere could help understand how it started here.

The connection between evolution and exoplanets has an added and essential dimension when it comes to hunting for signatures of distant extraterrestrial life.

Searching for a planet with lots of oxygen and other atmospheric compound in disequilibrium (as on Earth) is certainly a way forward. But it is sobering to realize that those biosignatures would not have been detectable on Earth for most of the time that life has been present.  That’s because large concentrations of oxygen are a relative newcomer to our planet,  product of biological evolution.

With all this in mind, it seems both interesting and useful to look at the work of a researcher studying the fossil record to better understand a particular transition on Earth — the one from simpler organisms to multicellular creatures that can be considered animals.

The surprising, large transitional life of the Ediacaran period, which just preceded the Cambrian explosion of complex life. This grouping is termed the Ediacara assemblage, and existed late in the period.  (John Sibbick)

The researcher is Jennifer Hoyal Cuthill of the University of Cambridge, who I first met at the Earth-Life Science Institute in Tokyo, a unique place where scientists research the origin of Earth and of life on Earth.

She had been included in a group of twelve two-year fellows recruited from around the world who specialized in fields ranging from the microbiology of extreme environments to the current and past dynamics of the deep Earth and the digital world of chemo informatics.  And then there was Hoyal Cuthill, whose field is paleobiology, with a heavy emphasis on evolution.… Read more

Large Reservoir of Liquid Water Found Deep Below the Surface of Mars

Artist impression of the Mars Express spacecraft probing the southern hemisphere of Mars, superimposed on a radar cross section of the southern polar layered deposits. The leftmost white line is the radar echo from the Martian surface, while the light blue spots are highlighted radar echoes along the bottom of the ice.  Those highlighted areas measure very high reflectivity, interpreted as being caused by the presence of water. (ESA, INAF. Graphic rendering by Davide Coero Borga )

Far beneath the frigid surface of the South Pole of Mars is probably the last place where you might expect the first large body of Martian liquid water would be found.  It’s -170 F on the surface, there are no known geothermal sources that could warm the subterranean ice to make a meltwater lake, and the liquid water is calculated to be more than a mile below the surface.

Yet signs of that liquid water are what a team of Italian scientists detected — a finding that they say strongly suggests that there are other underground lakes and streams below the surface of Mars.  In a Science journal article released today, the scientists described the subterranean lake they found as being about 20 kilometers in diameter.

The detection adds significantly to the long-studied and long-debated question of how much surface water was once on Mars, a subject that has major implications for the question of whether life ever existed on the planet.

Finding the subterranean lake points to not only a wetter early Mars, said co-author Enrico Flamini of the Italian space agency, but also to a Mars that had a water cycle that collected and delivered the liquid water.  That would mean the presence of clouds, rain, evaporation, rivers, lakes and water to seep through surface cracks and pool underground.

Scientists have found many fossil waterways on Mars, minerals that can only be formed in the presence of water, and what might be the site of an ancient ocean.

But in terms of liquid water now on the planet, the record is thin.  Drops of water collected on the leg of NASA’s Phoenix Lander after it touched down in 2008, and what some have described as briny water appears to be flowing down some steep slopes in summertime.  Called recurrent slope lineae or RSLs, they appear at numerous locations when the temperatures rise and disappear when they drop.

This lake is different, however, and its detection is a major step forward in understanding the history of Mars.… Read more

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