Artifacts In Space

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Voyager 2 entered interstellar space last month, becoming a space “artifact” of our civilization. (NASA)

 

All of a sudden, we have spacecraft and objects coming into our solar system and leaving for interstellar space. This is highly unusual, and very intriguing.

The departing spacecraft is Voyager 2, which launched in 1977 and has traveled spaceward some 11 billion miles.  It has now officially left the heliosphere, the protective bubble of particles and magnetic fields created by the sun.  In this it follows Voyager I – which left our solar system in 2012 — and managers of the two craft have reason to think they can travel until they cross the half-century mark.

This is taking place the same time that scientists are puzzling over the nature of a cigar-shaped object that flew into the solar system from interstellar space last year.

Nobody knows what the object – called Oumuamua, Hawaiian for “first messenger,” or “scout” – really is. The more likely possibilities of it being a comet or an solar system asteroid have been found to be inconsistent with some observed properties of the visitor, and this has led some senior scientists to even hypothesize that it just might be an alien probe.

The likelihood may be small, but it was substantial enough for Harvard University Astronomy Department Chairman Avi Loeb to co-author a paper presenting the possibility.  In the Astrophysical Journal Letters, Loeb and postdoc Shmuel Bialy wrote that the object “may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization.”

They also say the object has some characteristics of a “lightsail of artificial origins,” rather like the one that Loeb is working on as chairman of the Breakthrough Starshot advisory committee.  The well-funded private effort is hoping to develop ways to send a fleet of tiny lightsail probes to the star system nearest to us, Alpha Centauri.

 

This artist’s impression of the first detected interstellar visitor: Oumuamua. This object was discovered in October 2017 by the Pan-STARRS 1 telescope in Hawaii. Subsequent observations from ESO’s Very Large Telescope in Chile and other observatories around the world show that it was traveling through space for millions of years before its seemingly chance encounter with our star system.  But some scientists wonder:  might it be instead a probe sent into the cosmos by intelligent creatures?(NASA)

 

Put the two phenomenon together — the coming into our solar system and the going out — and you have a pathway into the world of alien “artifacts,” products of civilizations near and far.  They are the kind of “technosignatures,” the potential or actual handwork of intelligent beings, that NASA is now interested in learning about more.

We know this because during a fall conference in Houston convened by NASA at the request of members of Congress, scientists were brought together to discuss many different kinds of potential signs of intelligent extraterrestrial life.  While artifacts were one of many topics discussed, the term carries a quite magnetic pedigree.

So far, that meaning is of course fictional, or a misreading of actual features.  There is perhaps most famously the monoliths from the movie “2001: A Space Odyssey” and then the myriad sightings of alien spacecraft that turn out to be anything but that.

This image taken by VIking 1 in the mid 1970s led to years of discussion about Martian beings having at one time carved what appeared to be a gigantic face. (NASA)

 

And then there’s the “Face on Mars.”

The original image taken by Viking 1 looked somewhat like a human face. The feature, found in the region where the highlands meet the northern plains of Mars, was subsequently broadly popularized as a potential “alien artifact,” with even a major motion picture.

So many people were convinced that an image had been sculpted on the surface of Mars that NASA ultimately put out a substantial release in 2001 to make clear that the face was actually a mountain.

That was after the Mars Global Surveyor orbiter determined that the “face” was created by unusual reflections in an otherwise ordinary Martian mountain.

This high-resolution image from the Mars Orbiter Camera about the Mars Global Surveyor spacecraft shows the famous “Face on Mars” in detail, clearly showing it to be a natural geological formation. (NASA/MSSS)

 

 

So alien artifacts surely and properly have a steep hill to climb before they can be taken at all seriously.

But does that mean they shouldn’t be taken seriously at all?  Loeb clearly says no, that they are a potential source of important and compelling science, even if they are natural phenomena.

And then there’s the question raised in the Houston “technosignatures” conference:  What actually is meant by an artifact?

Longtime SETI scientist and advocate Jill Tarter, for instance, wondered if the signatures of intelligent civilizations could be imprinted on neutrinos.  She said that a leak of the radioactive isotope tritium, which has a short 12-year half-life,  could also signal the presence of advanced life because (unless it’s near a supernova) it would have to come quite recently from a nuclear reactor.

Taking it further, she and others argued that artifacts of intelligent life would include many atmospheric and planetary changes that could only be accomplished by intelligent beings.  For instance, the presence of unnatural pollutants such as chloroflurocarbons (CFCs) or sulfur hexafluoride (SF6) in an exoplanet atmosphere would, in this view, be an “artifact” of civilization.

Back, now, to Voyager 2, which is for sure an extraterrestrial artifact.

 

Rendering of Voyager 2 in deep space. (NASA/JPL)

 

Voyager 2 was launched by NASA in August, 1977 to study the outer planets.  Part of the larger Voyager program, it was launched 16 days before its twin, Voyager 1, on a trajectory that took longer to reach Jupiter and Saturn but enabled further encounters with Uranus and Neptune.

Both have traveled far their original destinations. The spacecraft were built to last five years and conduct close-up studies of Jupiter and Saturn.  With the spacecraft holding up despite the rigors,  additional flybys of the two outermost giant planets, Uranus and Neptune, proved possible, and then the Voyagers were directed to interstellar space.

Their five-year lifespans have stretched to 41 years, making Voyager 2 NASA’s longest running mission ever.

At the on-going American Geophysical Union annual meeting, NASA project manager Suzanne Dodd said she believed that Voyager 2 can keep functioning for 5 to 10 more years in this new region of space, though not with all its instruments operating.

The greatest concerns about keeping the probes operating, she said, involve power and temperature. The  nuclear-powered Voyager 2 loses about 4 watts of power a year, and mission scientists have to shut off systems to keep instruments operating.

Voyager 2 is very cold — about 3.6 degrees Celsius and close to the freezing point of hydrazine — leading to concerns about the probe’s thruster that uses this fuel.  Dodd says she’s set a personal goal of keeping at least one of the Voyagers going until 2027, making it a 50-year mission.

The cameras for both probes are no longer on. But before the camera on Voyager 1 was decommissioned, it took the iconic “Pale Blue Dot” picture of the Earth.

 

 

This “Pale Blue Dot” image was captured in 1990, when Voyager 1 was about 4 million miles from Earth.  The spacecraft is now more than 13 billion miles from where it launched. (NASA)

 

In preparation for the potentially deep space travels for the Voyager spacecrafts, both were fitted with a greeting for any intelligent life that might be encountered.

The message is carried by a phonograph record – -a 12-inch gold-plated copper disk containing sounds and images selected to show the diversity of life and culture on Earth. The contents of the record were selected for NASA by a committee chaired by space scientist and popularizer Carl Sagan.  He and his associates assembled 115 images and a variety of natural sounds to give a sense of what Earth and Earthlings are like.

So are the Voyagers now artifacts from our civilization, messengers awaiting discovery by some distant beings?

Perhaps.  But they actually have not even left the solar system, and won’t be leaving anytime soon. They are in what is considered interstellar space, but the boundary of our solar system is beyond the outer edge of the Oort Cloud, a collection of small objects that are still under the influence of the sun’s gravity.

The width of the Oort Cloud is not known precisely, but it is estimated to begin at about 1,000 astronomical units (AU) from the sun and to extend to about 100,000 AU. One AU is the distance from the sun to Earth. It will take about 300 years for Voyager 2 to reach the inner edge of the Oort Cloud and possibly 30,000 years to fly beyond it.

 

The path of Oumuamua since it entered the solar system in 2017. (NASA)

 

Astronomers have long predicted that objects from other solar systems get shot out into space and arrive in our system.

The first identified interstellar object to visit our solar system, Oumuamua, was discovered in late 2017 by the University of Hawaii’s Pan-STARRS1 telescope as part of a NASA effort to search for and track asteroids and comets in Earth’s neighborhood.

While originally classified as a comet, observations revealed no signs of cometary activity after it was slingshotted around the sun at a remarkable 196,000 miles per hour.

Oumuamua seems to be a dark red highly-elongated metallic or rocky object that (at last analysis) is somewhere between 400 and 100 meters long and is unlike anything normally found in the solar system.  Researchers hypothesize that the shape and size suggest that the object has been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years.

Karen Meech of the University of Hawaii first identified Oumuamua. Here she is giving a TED Talk.

Immediately after its discovery, telescopes around the world were called into action to measure the object’s trajectory, brightness and color.  Combining the images from several large telescopes,  a team of astronomers led by Karen Meech of the Institute for Astronomy in Hawaii found that Oumuamua varies in brightness by a factor of 10 as it spins on its axis every 7.3 hours.

 

Avi Loeb, chair of the Harvard Astronomy Department and an advocate of thinking way outside the box about Oumuamua.

 

No known asteroid or comet from our solar system varies so widely in brightness, with such a large ratio between length and width. The most elongated objects we have seen to date are no more than three times longer than they are wide.

“This unusually big variation in brightness means that the object is highly elongated: about ten times as long as it is wide, with a complex, convoluted shape,” said Meech. “We also found that it had a reddish color, similar to objects in the outer solar system, and confirmed that it is completely inert, without the faintest hint of dust around it.”

Oumuamua is headed out of the solar system now, so it’s unlikely more will be learned about it.  And with its odd shape and features, it clearly remains something of a mystery.

And that’s where Harvard’s Avi Loeb comes in.  Especially due to the remarkably fast speed with which Oumuamua entered the solar system, he argues that a probe sent by intelligent others cannot be ruled out, that science must be open minded.

“There is data on the orbit of this object for which there is no other explanation” than that it is the product of intelligent others,” he has said.  “The approach I take to the subject is purely scientific and evidence-based.”

Others strongly disagree.  But the views of the chairman of the Harvard astronomy department are nonetheless an intriguing part of the story.

 

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InSight Lands on Mars For Unique Mission

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NASA’s InSight Lander has returned its first picture from Mars via the MarCO CubeSat mission. (NASA)

 

NASA’s InSight lander touched down at 11:54 Pacific Time and followed a seven-month, 300 million-mile (485 million kilometer) journey from Southern California that started back in May.

InSight will spend the next few hours cleaning its camera lens and unfurling its solar arrays.

Once NASA confirms that the solar arrays have been properly deployed, engineers will spend the next three months preparing the lander’s science instruments to begin collecting data.

The touchdown continues NASA’s good fortunes with Mars landings, and is the fifth successful landing in a row.

Only 40% of missions by any agency sent to pass by, orbit or land on Mars have been successful, and NASA has certainly had some failures, too.

This is by way of saying that any successful mission to Mars is a great accomplishment.

The European Space Agency, the Indian Space Research Organisation and the team of ESA and Russia’s Roscosmos currently have satellites orbiting the planet, and Japan, China. Russia and the United Arab Emirates have Mars missions planned for the next decade.  The next NASA mission to the planet is the Mars 2020 rover, a follow-up to the still exploring Curiosity rover which landed in 2012.

 

For those who might have missed it, here is our recent Many Worlds column about the novel science planned for InSight:

 

An artist illustration of the InSight lander on Mars. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is designed to look for tectonic activity and meteorite impacts, study how much heat is still flowing through the planet, and track Mars’ wobble as it orbits the sun. While InSight is a Mars mission, it will help answer key questions about the formation of the other rocky planets of the solar system and exoplanets beyond. (NASA/JPL-Caltech)

In the known history of our 4.5-billion-year-old solar system,  the insides of but one planet have been explored and studied.  While there’s a lot left to know about the crust, the mantle and the core of the Earth, there is a large and vibrant field dedicated to that learning.

Sometime next month, an extensive survey of the insides of a second solar system planet will begin.  That planet is Mars and, assuming safe arrival, the work will start after the InSight lander touches down on November 26.

This is not a mission that will produce dazzling images and headlines about the search for life on Mars.  But in terms of the hard science it is designed to perform, InSight has the potential to tell us an enormous amount about the makeup of Mars, how it formed, and possibly why is it but one-third the size of its terrestrial cousins, Earth and Venus.

“We know a lot about the surface of Mars, we know a lot about its atmosphere and even about its ionosphere,” says Bruce Banerdt, the mission’s principal investigator, in a NASA video. “But we don’t know very much about what goes on a mile below the surface, much less 2,000 miles below the surface.”

The goal of InSight is to fill that knowledge gap, helping NASA map out the deep structure of Mars.  And along the way, learn about the inferred formation and interiors of exoplanets, too.

Equitorial Mars and the InSight landing site, with noting of other sites. (NASA)

The lander will touch down at Elysium Planitia, a flat expanse due north of the Curiosity landing site.  The destination was selected because it is about as safe as a Mars landing site could be, and InSight did not need to be a more complex site with a compelling surface to explore.

“While I’m looking forward to those first images from the surface, I am even more eager to see the first data sets revealing what is happening deep below our landing pads.” Barerdt said. “The beauty of this mission is happening below the surface. Elysium Planitia is perfect.”

By studying the size, thickness, density and overall structure of the Martian core, mantle and crust, as well as the rate at which heat escapes from the planet’s interior, the InSight mission will provide glimpses into the evolutionary processes of all of the rocky planets in the inner solar system.

That’s because in terms of fundamental processes that shape planetary formation, Mars is an ideal subject.

It is big enough to have undergone the earliest internal heating and differentiation (separation of the crust, mantle and core) processes that shaped the terrestrial planets (Earth, Venus, Mercury, our moon), but small enough to have retained the signature of those processes over the next four billion years.

So Mars may contain the most in-depth and accurate record in the solar system of these processes. And because Mars has been less geologically active than the Earth — it does not have plate tectonics, for example —  it has retains a more complete evolutionary record in its own basic planetary building blocks.  In terms of deep planet geophysics,  it is often described as something of a fossil.

 

An artist rendering of the insides of rocky body like Mars.  The manner in which the different layers form and differentiate is seen as a central factor in whether the planet can become habitable.  (NASA)

 

By using geophysical instruments like those used on Earth, InSight will measure the fingerprints of the processes of terrestrial planet formation, as well as measuring the planet’s “vital signs.” They include the  “pulse” (seismology), “temperature” (heat flow probe), and “reflexes” (precision tracking).

One promising way InSight will peer into the Martian interior is by studying motion underground — what we know as marsquakes.

NASA has not attempted to do this kind of science since the Viking mission. Both Viking landers had their seismometers on top of the spacecraft, where they produced noisy data. InSight’s seismometer will be placed directly on the Martian surface, which will provide much cleaner data.

As described by the agency, “NASA have seen a lot of evidence suggesting Mars has quakes. But unlike quakes on Earth, which are mostly caused by tectonic plates moving around, marsquakes would be caused by other types of tectonic activity, such as volcanism and cracks forming in the planet’s crust.

“In addition, meteor impacts can create seismic waves, which InSight will try to detect.

“Each marsquake would be like a flashbulb that illuminates the structure of the planet’s interior. By studying how seismic waves pass through the different layers of the planet (the crust, mantle and core), scientists can deduce the depths of these layers and what they’re made of. In this way, seismology is like taking an X-ray of the interior of Mars.”

 

The InSight seismometer, developed by European partners and JPL, consists of a total of six seismic sensors that record the vibrations of the Martian soil in three directions in space and at two different frequency ranges. ges allows them to be mathematically combined into a single extremely broadband seismometer.  In order to protect the seismometer against wind and strong temperature fluctuations, a protective dome (Wind and Thermal Shield, WTS) will be placed over it. (German Aerospace Center)

 

Scientists think it’s likely they’ll see between a dozen and a hundred marsquakes over the course of two Earth years. The quakes are likely to be no bigger than a 6.0 on the Richter scale, which would be plenty of energy for revealing secrets about the planet’s interior.

Another area of scientific interest involves whether or not the core of Mars is liquid. InSight’s Rotation and Interior Structure Experiment, RISE, will help answer that question by tracking the location of the lander to determine just how much Mars’ North Pole wobbles as it orbits the sun.

These observations will provide information on the size of Mars’ iron-rich core and will help determine whether the core is liquid.  It will also help determine which other elements, besides iron, may be present.

The InSight science effort includes a self-hammering heat probe that will burrow down to 16 feet into the Martian soil and will for the first time measure the heat flow from the planet’s interior. Combining the rate of heat flow with other InSight data will reveal how energy within the planet drives changes on the surface.

This is especially important in trying to understand the presence and size of some of the solar system’s largest shield volcanoes in the solar system, a region known as Tharsis Mons.  Heat escaping from deep within the planet drives the formation of these types of features, as well as many others on rocky planets.

 

The Tharsis region of Mars has some of the largest volcanoes in the solar system. They include Olympus Mons, which is 375 miles in diameter and as much as 16 miles high. (U.S. Geological Survey)

InSight is not an astrobiology mission — no searching for life beyond Earth.

But it definitely is part of the process by which scientists will learn what planet formation and the dynamics of their interiors says about whether a planet can be home to life.

 

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Probing The Insides of Mars to Learn How Rocky Planets Are Formed

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An artist illustration of the InSight lander on Mars. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is designed to look for tectonic activity and meteorite impacts, study how much heat is still flowing through the planet, and track Mars’ wobble as it orbits the sun. While InSight is a Mars mission, it will help answer key questions about the formation of the other rocky planets of the solar system and exoplanets beyond. (NASA/JPL-Caltech)

In the known history of our 4.5-billion-year-old solar system,  the insides of but one planet have been explored and studied.  While there’s a lot left to know about the crust, the mantle and the core of the Earth, there is a large and vibrant field dedicated to that learning.

Sometime next month, an extensive survey of the insides of a second solar system planet will begin.  That planet is Mars and, assuming safe arrival, the work will start after the InSight lander touches down on November 26.

This is not a mission that will produce dazzling images and headlines about the search for life on Mars.  But in terms of the hard science it is designed to perform, InSight has the potential to tell us an enormous amount about the makeup of Mars, how it formed, and possibly why is it but one-third the size of its terrestrial cousins, Earth and Venus.

“We know a lot about the surface of Mars, we know a lot about its atmosphere and even about its ionosphere,” says Bruce Banerdt, the mission’s principal investigator, in a NASA video. “But we don’t know very much about what goes on a mile below the surface, much less 2,000 miles below the surface.”

The goal of InSight is to fill that knowledge gap, helping NASA map out the deep structure of Mars.  And along the way, learn about the inferred formation and interiors of exoplanets, too.

Equitorial Mars and the InSight landing site, with noting of other sites. (NASA)

The lander will touch down at Elysium Planitia, a flat expanse due north of the Curiosity landing site.  The destination was selected because it is about as safe as a Mars landing site could be, and InSight did not need to be a more complex site with a compelling surface to explore.

“While I’m looking forward to those first images from the surface, I am even more eager to see the first data sets revealing what is happening deep below our landing pads.” Barerdt said. “The beauty of this mission is happening below the surface. Elysium Planitia is perfect.”

By studying the size, thickness, density and overall structure of the Martian core, mantle and crust, as well as the rate at which heat escapes from the planet’s interior, the InSight mission will provide glimpses into the evolutionary processes of all of the rocky planets in the inner solar system.

That’s because in terms of fundamental processes that shape planetary formation, Mars is an ideal subject.

It is big enough to have undergone the earliest internal heating and differentiation (separation of the crust, mantle and core) processes that shaped the terrestrial planets (Earth, Venus, Mercury, our moon), but small enough to have retained the signature of those processes over the next four billion years.

So Mars may contain the most in-depth and accurate record in the solar system of these processes. And because Mars has been less geologically active than the Earth — it does not have plate tectonics, for example —  it has retains a more complete evolutionary record in its own basic planetary building blocks.  In terms of deep planet geophysics,  it is often described as something of a fossil.

 

An artist rendering of the insides of rocky body like Mars.  The manner in which the different layers form and differentiate is seen as a central factor in whether the planet can become habitable.  (NASA)

 

By using geophysical instruments like those used on Earth, InSight will measure the fingerprints of the processes of terrestrial planet formation, as well as measuring the planet’s “vital signs.” They include the  “pulse” (seismology), “temperature” (heat flow probe), and “reflexes” (precision tracking).

One promising way InSight will peer into the Martian interior is by studying motion underground — what we know as marsquakes.

NASA has not attempted to do this kind of science since the Viking mission. Both Viking landers had their seismometers on top of the spacecraft, where they produced noisy data. InSight’s seismometer will be placed directly on the Martian surface, which will provide much cleaner data.

As described by the agency, “NASA have seen a lot of evidence suggesting Mars has quakes. But unlike quakes on Earth, which are mostly caused by tectonic plates moving around, marsquakes would be caused by other types of tectonic activity, such as volcanism and cracks forming in the planet’s crust.

“In addition, meteor impacts can create seismic waves, which InSight will try to detect.

“Each marsquake would be like a flashbulb that illuminates the structure of the planet’s interior. By studying how seismic waves pass through the different layers of the planet (the crust, mantle and core), scientists can deduce the depths of these layers and what they’re made of. In this way, seismology is like taking an X-ray of the interior of Mars.”

 

The InSight seismometer, developed by European partners and JPL, consists of a total of six seismic sensors that record the vibrations of the Martian soil in three directions in space and at two different frequency ranges. ges allows them to be mathematically combined into a single extremely broadband seismometer.  In order to protect the seismometer against wind and strong temperature fluctuations, a protective dome (Wind and Thermal Shield, WTS) will be placed over it. (German Aerospace Center)

 

Scientists think it’s likely they’ll see between a dozen and a hundred marsquakes over the course of two Earth years. The quakes are likely to be no bigger than a 6.0 on the Richter scale, which would be plenty of energy for revealing secrets about the planet’s interior.

Another area of scientific interest involves whether or not the core of Mars is liquid. InSight’s Rotation and Interior Structure Experiment, RISE, will help answer that question by tracking the location of the lander to determine just how much Mars’ North Pole wobbles as it orbits the sun.

These observations will provide information on the size of Mars’ iron-rich core and will help determine whether the core is liquid.  It will also help determine which other elements, besides iron, may be present.

The InSight science effort includes a self-hammering heat probe that will burrow down to 16 feet into the Martian soil and will for the first time measure the heat flow from the planet’s interior. Combining the rate of heat flow with other InSight data will reveal how energy within the planet drives changes on the surface.

This is especially important in trying to understand the presence and size of some of the solar system’s largest shield volcanoes in the solar system, a region known as Tharsis Mons.  Heat escaping from deep within the planet drives the formation of these types of features, as well as many others on rocky planets.

 

The Tharsis region of Mars has some of the largest volcanoes in the solar system. They include Olympus Mons, which is 375 miles in diameter and as much as 16 miles high. (U.S. Geological Survey)

InSight is not an astrobiology mission — no searching for life beyond Earth.

But it definitely is part of the process by which scientists will learn what planet formation and the dynamics of their interiors says about whether a planet can be home to life.

 

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Prepare For Lift-off! BepiColombo Launches For Mercury

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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. The planet’s density is very high, suggesting a much larger iron core relative to its volume compared to the Earth.

The thin atmosphere is mysteriously rich in sodium and there also appears to be more volatiles such as water ice than is expected for a planet that dances so close to the sun. All this points to a formation and evolution that we do not yet understand.

Artist impression of the JAXA orbiter, MIO, around Mercury (credit: JAXA).

The two BepiColombo orbiters will sweep around the planet to pick at these questions. The pair will get a global view of Mercury, in contrast to MESSENGER whose orbit did not allow a good view over the southern hemisphere.

“Getting data from the southern hemisphere to complement the details from MESSENGER is a logical next step to investigating the nature of Mercury’s magnetic field,” commented Masaki Fujimoto, Deputy Director General at JAXA’s Institute of Space and Astronautical Sciences (ISAS).

The European orbiter is the “Mercury Planetary Orbiter” (MPO), with “Bepi” as a nickname. Bepi will take a relatively close orbit around Mercury, with an altitude between 300 – 930 miles (480 – 1500 km). The main focus of the probe is the planet’s surface topology and composition, as well as a precise measurement of the gravitational field that reveals information about Mercury’s internal structure.

The Japanese orbiter is the “Mercury Magnetospheric Orbiter” (MMO) and was given the nickname “MIO” through a public contest held earlier this year and translates to “waterway” in Japanese.

Masaki Fujimoto, Deputy Director of ISAS, JAXA.

“Water related names received many votes,” explained Go Murakami, BepiColombo MIO project scientist. “Because in the Japanese language, Mercury is written ‘水星’ (suisei) meaning ‘water planet’.”

The focus for MIO is Mercury’s magnetic field and the interaction with the solar wind; a stream of high energy particles that comes from the sun. This requires exploration of the region around Mercury and MIO will take a correspondingly wider orbit than Bepi, with an altitude between 250 – 7500 miles (400 – 12,000km).

While Mercury itself is interesting, understanding the planet’s history has wide ranging implications for the search for habitable worlds around other stars.

The easiest exoplanets to spot are those on close orbits around dim red dwarf (also known as M-dwarf) stars. As they are far less luminous than our sun, even planets on close orbits around red dwarfs may receive a similar level of radiation to the Earth, placing them in the so-called “habitable zone.” An important example of this are the TRAPPIST-1 worlds, whose three habitable-zone planets have orbits lasting 6, 9 and 12 Earth days.

Go Murakami, BepiColombo MIO project scientist

However, the close proximity to the star comes with risks. Red dwarfs are particularly rambunctious, emitting flares that can strip the atmosphere of an orbiting planet. Mars is a classic example of this process.

Even orbiting a relatively quiet star at a distance further from the Earth, the thin atmosphere of Mars is being pulled away by the solar wind. Unless the TRAPPIST-1 worlds and those like them can protect their gases with a magnetic field, their surfaces may always be sterile.

While we know the Earth avoids this fate with its own magnetic field, it is not clear whether it would fare as well closer to the sun or with a weaker magnetic field. Mercury with its weak field and in the full blast of the solar wind offers an extreme comparison point.

A second insight Mercury could provide is that of the origin of rock. Planetary formation theories suggest there must have been mixing of dust grains in the planet-forming disc that circled the young sun. This would have shuffled up the elements that were condensing into solids at different temperatures within the disc. The exact nature and result of the shuffling remains a big question, yet it controls the composition of inner rocky planets that includes the Earth.

“The subject of planetary origins is very intriguing to me,” remarks Fujimoto. “JAXA’s asteroid sample return mission, Hayabusa2, is asking the question of where the water on Earth came from. BepiColombo will ask the complimentary question of how our planet’s rocky body was made.”

Together, the two orbiters cover a wide range of science of addressing these questions. They can also work as a pair by taking simultaneous measurements from different locations. This is particularly useful for analyzing time-varying events and also allows the planetary magnetic field to be separated out from the magnetic field carried by the solar wind.

The launch date for BepiColombo has been pushed back several times over the last few years. However, this has allowed for engineering improvements, and discoveries such as the TRAPPIST-1 planets have only added to the excitement of the mission.

“We are not unhappy about the launch delays,” said Fujimoto. “What has happened in planetary science during that period has made the expectation for BepiColombo even higher!”

The journey to the innermost planet is not a quick one. Due to arrive in 2025, the long duration is actually not due to distance but the need to brake. The pull from the sun’s gravity at such close proximity makes it hard for BepiColombo to slow sufficiently for the two probes to enter Mercury’s orbit.

The spacecraft therefore does nine planetary fly-bys; one by the Earth in April next year, then two for Venus and six for Mercury. The gravity of the planet can be used to slow down the spacecraft and allow Bepi and MIO to begin their main mission.

To my complete delight, ESA have started an animated series of shorts for the mission, similar to the cartoons for the Rosetta mission to comet 67P in 2014. These informative little videos depict the adventures of Bepi, MIO and the Mercury Transfer Module (MTM) that provides the propulsion to reach Mercury.

In addition to the videos, all three probes (and the mission itself) have twitter accounts @BepiColombo (main mission account), @esa_bepi (character account for Bepi which tweets in English), @jaxa_mmo (character account for MIO that tweets in English and Japanese) and @esa_mtm that tweets in… I’ll let you find that out!

The live launch feed from ESA is due to begin at 21:38 EDT on Friday, October 19. Good luck, BepiColombo!

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Human Space Travel, Health and Risk

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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. (NASA)

 

Kamal Datta, an associate professor in the Department of Biochemistry is project leader of the NASA Specialized Center of Research (NSCOR) at Georgetown and has been studying the effects of space radiation on humans for more than a decade.

He said that heavy ions (electrically charged atoms and molecules) of elements such as iron and silicon are damaging to humans because of their greater mass compared to mass-less photons such as x-rays and gamma rays prevalent on Earth.  These heavy ions, as well as low mass protons, are ubiquitous in deep space.

Kamal Datta of Georgetown University Medical Center works with NASA to understand the potential risks from galactic cosmic radiation to astronauts who may one day travel in deep space.

“With the current shielding technology, it is difficult to protect astronauts from the adverse effects of heavy ion radiation. Although there may be a way to use medicines to counter these effects, no such agent has been developed yet,” says Datta, also a member of Georgetown Lombardi Comprehensive Cancer Center.

“While short trips, like the times astronauts traveled to the moon, may not expose them to this level of damage, the real concern is lasting injury from a long trip, such as a Mars or other deep space missions which would be much longer” he said in a release.

Datta’s team has also published on the potentially harmful effects of galactic cosmic radiation on the brain and other teams are looking at potential deep-space travel dangers the human cardio-vascular system.  Researchers are also concerned about known weakening of bone and muscle tissue, harming vision, as well as speeded-up aging during long stays in space.

With current technology, it would take about three years to travel from Earth to Mars, orbit the planet until it is in the right place for a sling-shot boost home, and then to travel back.

A radiation detection instrument on the Mars Science Laboratory (MSL),  which carried the rover Curiosity to Mars in 2011-2012, measured an estimated overall human radiation exposure for a Mars trip that would would be two-thirds of the agency’s allowed lifetime limits.  That was based on the high-energy radiation hitting the capsule, but NASA later detected radiation bursts from solar flares on Mars far higher than anything detected during the MSL transit.

All of this seems, and is, quite daunting when thinking about human travel to Mars and other deep space destinations.  And Datta is clearly sensitive about how the new results are conveyed to the public.

“I am in no way saying that people cannot travel to Mars,” he told me. “What we are doing is trying to understand the health risks so proper mitigation can be devised, not to say this kind of travel is impossible.”

“We don’t have medicines now to protect astronauts from heavy particle radiation, and we don’t have the technology now to shield them while they’re in space.  But many people are working on these problems.”

 

The Orion spacecraft in flight, as drawn by an artist. The capsule has an attached habitat module. (NASA)

 

On the medical research side, scientists have to rely on data gained from exposing mice to radiation and extrapolating those results to humans.  It would, of course, be unethical to do the testing on people.

While this kind of animal testing is accepted as generally accurate, it certainly could hide either increased protections or increased risks in humans.

Datta said that another testing issue that has been present so far is that the mice have had to be irradiated in one large dose rather than in much smaller doses over time.  It is unclear how that effects the potential damage to human organs and the breaking of DNA bonds (which can result in the growth of cancers.)  But Datta said that new instruments at NASA’s Space Radiation Laboratory (NSRL) at the Brookhaven National Laboratory on Long Island, New York, will allow for a more gradual, lower-dose experiment.

While Datta’s work has been focused on the health risks of deep space travel, galactic cosmic radiation and solar heavy particles also bombard the moon — which has no magnetic field and only a very thin atmosphere to protect it.  Apollo astronauts could safely stay on the moon for several days in their suits and their lander, but months or years of living in a colony there would pose far greater risks.

NASA has actually funded projects to shield small areas on the moon from radiation, but the issue remains very much unresolved.

Shielding also plays a major role in thinking about how to protect astronauts traveling into deep space.  The current aluminum skin of space capsules allows much of the harmful radiation to pass through, and so something is needed to block it.

 

The goal of building an inhabited colony on the moon has many avid supporters in government and the private sector. The health risks for astronauts are similar to those in deep space. (NASA/Pat Rawlings)

 

Experts have concluded that perhaps the best barrier to radiation would be a layer of water, but it is too heavy to carry in the needed amounts.  Other possibilities include organic polymers (large macromolecules with repeating subunits) such as polyethelyne.

It seems clear that issues such as these — the effects of more hazardous space radiation on astronauts in deep space and on the moon, and how to minimize those dangers — will be coming to the front burner in the years ahead.  And assuming that progress can be made, it’s a thrilling time.

What this means for space science, however, is less clear.

On one hand I recall hearing former astronaut extraordinaire and then head of the NASA Science Mission Directorate John Grunsfeld talk about how an astronaut on Mars could gather data and understandings in one week that the Curiosity rover would need a full year to match.

On the other, human space exploration is much more expensive than anything without people — yes, even including the long-delayed and ever-more-costly James Webb Space Telescope — and NASA budgets are limited.

So the question arises whether human exploration will, when it gets into high gear, swallow up the resources needed for the successors to the Hubble, Curiosity, Cassini and the other missions that have helped create what I consider to be a golden age of space science.  Risks come in many forms.

 

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