GJ 1214b Water World

The Kepler space telescope, which started operation on March 6^th, 2009, is one of a number of new projects aimed at discovering extra-solar planets.  This goal, which was once just a dream of astronomers, has been realized in recent years due to a number of new telescopes, spearheaded by the Kepler space telescope, a 37 inch telescope dedicated to finding new planets (Britannica).  Although it was previously believed that planets might be scarce, and that our system rather special, the new data revealed by Kepler and other telescopes have revealed hundreds of planets orbiting foreign stars.  Though initially the only planets we were able to detect were large, massive Jovian planets, more recently we have been able to detect many terrestrial planets.  Most are a few times more massive than Earth, and have been dubbed, “super earths” for their size and terrestrial nature. 

The methods for finding planets are varied and numerous.  The six methods used today are pulsar timing, astrometry, Doppler shift, direct imaging, transits and micro-lensing.  Of these six, by far the most commonly used are transits, astrometry and Doppler shift.  The transit method, used by the Kepler telescope, looks at the changes in luminosity of stars as planets transit their disc (Britannica).  This method can be very accurate, but is not infallible; multi star or planet systems need complex models to be understood, and this method is prone to finding very large planets, not the small terrestrial ones that could support life.  Another weakness is that this method requires the plane of the system to be in line with ours, further limiting its usefulness.  Doppler shift and astrometry are very similar.  Both look at the movement of stars as they orbit the center of mass of their system to find planets.  By breaking down the star’s orbit and fitting it to a model, we can predict the mass and placement of the surrounding planets.  The difference in these methods lies in how they collect data.  The Doppler shift method, as the name suggests, uses the red or blue shift of the star to model the orbit while astrometry uses imaging.  Both methods are prone to detecting Jovian planets much more frequently than terrestrial ones, but both have been used to great effect.

One planet detected by the transit method is Gliese 1214b or GJ 1214b.  Detected as part of the MEarth Project, GJ 1214b has a radius roughly 2.6 times larger than that of Earth, and mass around 7 times greater than Earths.  Orbiting a small, dim, M class dwarf star called GJ 1214, GJ 1214b is only 47 light years from Earth, just a step away compared to most other super-Earths.  Though little is directly known of the planet’s composition due to its thick atmosphere, its low density tells us that it is likely to be a water world, with much less rock than Earth (Wiki, GJ 1214b).  The current proposed model, pictured above, would make this planet a prime candidate for life, with a hot atmosphere and a huge, warm sea.  The planet’s heat is due to its proximity to its host star.  With a semi major axis of just .014 AU, GJ 1214b orbits closer to its star than any body in our solar system.  This proximity is not problematic for life due to the star’s (GJ 1214’s) low temperature and luminosity (Wiki, GJ 1214b).  The atmosphere of GJ 1214b is very thick, low Raleigh scattering provides evidence of a water rich atmosphere.   Raleigh scattering is a technique that looks at how starlight is scattered as it goes through the atmosphere of a planet to determine its composition.  Because some low levels of scattering are observed, but very little light goes all the way through the atmosphere, we can conclude that a cloudy, water rich atmosphere is likely (Daily Mail).  One more factor that makes life possible on GJ 1214b has to do with the star it orbits.  Dwarf stars are very stable and very long-lived, giving life lots of time to evolve, unlike high mass stars which burn through their fuel faster, and so live shorter lives. 

Due to these factors GJ 1214b is a prime candidate for further study, and one of the most likely places that life could exist in a system close to ours.  The conservative boundaries of the habitable zone around a star are given as such:

D_inner = .95AU√(L_star/L_sun) and

D_outer = 1.4AU√(L_star/L_sun)

Given GJ 1214’s luminosity we can calculate the habitable zone

D_inner = .95AU√(.00328☉)

D_outer = 1.4AU√(.00328☉)

So the habitable zone around GJ 1214b is between .054 AU and .081 AU. 

Though the orbit of GJ 1214b is outside these limits, it does not mean that the planet cannot support life.  These equations do not take into account any atmospheric effects, nor does it use albedo to determine temperatures.  To find a more accurate indication of temperature we can use an equation for equilibrium temperature.  This too does not include atmospheric effects, but will still give a better idea of the temperatures on GJ 1214b.

4πσ(T_eq)⁴ = (1-A)(L_★/4d²)

Where σ is the Stefan-Boltzmann constant (5.670373 × 10⁻⁸ W m⁻² K⁻⁴), A is the albedo, L_★ is the luminosity of the star in watts, d is the semi-major axis of the planet’s orbit in meters and T_eq is the equilibrium temperature in degrees kelvin.  Though we cannot directly measure the albedo of GJ 1214b, our best models put it at around .4 (astro.ex.ac.uk).

4π(5.670373 × 10⁻⁸ W m⁻² K⁻⁴ )(T_eq)⁴ = (1-.4)(1.259192 x 10²⁴ W/4((2.139 × 10⁹m)²)

(7.12560086 x 10^-7 W m⁻² K⁻⁴)(T_eq)⁴ = 41240 kg / s³

(T_eq)⁴ = (41240 kg / s³)/ (7.12560086 x 10^-7 W m⁻² K⁻⁴)

T_eq = 490.4 K

This temperature, while hot, could still support liquid water at different depths (and pressures).  Using different models and different albedos scientists have put GJ 1214b’s temperature at somewhere between 393 and 555 degrees kelvin, or around 120 – 282^oC.

Though these temperatures are to hot for most terrestrial life to survive in, Methanopyrus kandleri and Geogemma barossii are both microorganisms that can survive and even reproduce in temperatures of greater than 120^oC (NSF).  While that is still on the lower end of the predicted range, evolution could make more species suitable for these conditions. 

            As previously mentioned, the star GJ 1214 is an M-class red dwarf.  This is important in determining the possibility of life on GJ 1214b because dwarf stars have very long lives, giving plenty of time for life to evolve.  A red dwarf’s life cycle is different than that of a massive star.  A high mass star, such as VY Canis Majoris, which has a radius of approximately 6.6 AU, and is around 20 times more massive than the sun, has a lifetime of around two million years, far too short for life to evolve.  Unlike these massive stars, red dwarfs are expected to live up to 10 trillion years, giving life plenty of time to evolve.

            GJ 1214b shows promise as a life-bearing planet due to a number of characteristics.  Its composition, primarily water, is perhaps the most exciting of them all, water is a well known necessity for terrestrial life, and its use as a solvent and catalyst is crucial for life.  While other liquids could be used for the same purpose, water is the best we have found so far, with a wide variety of temperatures at which it can remain liquid.  The planet’s temperature, while extreme by terrestrial standards are still within the limits of life on Earth, and could be considered pedestrian by extraterrestrial life.  Other characteristics such as its water rich atmosphere and long-lived star provide additional support to the idea that life may exist on GJ 1214b.  Its proximity and the aforementioned characteristics make GJ 1214b a prime candidate for further investigation and study.

Works Cited:

 “GJ 1214” Wikipedia: The Free Encyclopedia. Wikimedia Foundation.  Web.  Oct. 22, 2013. http://en.wikipedia.org/wiki/GJ_1214_b

“Kepler.” Encyclopædia Britannica. Encyclopædia Britannica Online Academic Edition. Encyclopædia Britannica Inc., 2013. Web. 22 Oct. 2013. <http://www.britannica.com/EBchecked/topic/1474027/Kepler>.

“Kepler Telescope” Wikipedia: The Free Encyclopedia. Wikimedia Foundation.  Web.  Oct. 22, 2013.http://en.wikipedia.org/wiki/Kepler_telescope

Lovley, Derek. “Microbe from Depths Takes Life to Hottest Known Limit” NSF.  NSF.gov. Web. Oct 22, 2013. http://www.nsf.gov/od/lpa/news/03/pr0384.html

Marcy, Geoffrey.  “Extra Solar Planets: Water World Larger Than Earth” Nature. Nature.com.  Web. Oct. 22, 2013. http://www.nature.com/nature/journal/v462/n7275/full/462853a.html

Zolfagharifard, Ellie. “Super-Earth 40 light years away ‘is rich in water with a thick, steamy atmosphere’, confirm Japanese astronomers” The Daily Mail.  Daily Mail.  Web. Oct. 22, 2013. http://www.dailymail.co.uk/sciencetech/article-2412151/Super-Earth-GJ-1214b-40-light-years-away-rich-water-steamy-atmosphere.html

On Friday my class saw the movie, “Gravity”.  The movie is set in current day space; it opens with astronauts (George Clooney, Sandra Bullock) attempting to install a new instrument on the Hubble space telescope.  All is well until debris from a Russian nuclear test rips through satellites causing a huge cloud of scrap metal to speed towards the telescope and the exposed astronauts.  The third astronaut is killed immediately leaving Clooney and Bullock on their own to fend for themselves as the debris continues to orbit and pummel them.  Using Clooney’s EVA jet pack they make their way to the ISS, in hopes of using one of the re-entry vehicles.  As they arrive the debris hits them again, Clooney is pulled away and drifts to his death, Bullock enters the station and uses the damaged vehicle to travel to the Chinese station.  Once she arrives she enters another, operational re-entry vehicle and tumbles to earth, safely landing in a lake.

The movie, while fun to watch, is riddled with scientific inaccuracies.  To start with, there is only one stable orbital speed per radius, and in the movie the debris is orbiting in the same direction as the stations, making impacts impossible. Another is that George Clooney’s death defies Newton’s laws.  There is no force pulling him, and yet even after coming to rest he is still ripped from the para-cord he is clinging to upon his and Bullock’s arrival to the ISS.

Despite these and many other mistakes, “Gravity” is still a fun movie to watch.  Just remember to take the science with a grain on salt.

Today my class went to a lecture on large-scale conservation efforts, hoping that we could find parallels between conservation on Earth and terraforming on other planets.  Unfortunately, the lecture was primarily about gathering supporters and networking to help kick start various large-scale projects.  The speaker, knowledgeable as he was did not really discuss rebuilding ecosystems as he did discuss protecting those that already exist.

Despite this, the lecture was still interesting to me, and there were still a few ideas put out that could carry over to terraforming.  One of these ideas was the percent of land that must remain preserved for wildlife in order to sustain all of Earth’s current ecosystems.  While the speaker said that politicians typically quote 12% as the upper limit, most scientists put the number much higher, many are closer to 35% and some are higher still.  This relates to terraforming because in order to successfully and permanently terraform you need to create a self-sustaining ecosystem, and to ensure that the ecosystem in self-sustaining you must make sure that there is enough space.

Though they do not relate to our topic of space, the rest of the lecture was interesting nonetheless.  Of all the conservation projects proposed, the presenter seemed most excited about the “Spine of the Continent” proposal.  This proposal would conserve an area stretching from Yellowstone north through Glacier and well into Canada.  This project would protect tens of millions of acres of land, ensuring that species such as the Grizzly Bear and Bison have ample area to graze and live free from human disruption.  Other projects include the conservation of the Pacific Northwest, and British Colombia, the vast central boreal forests of Canada and the Eastern coast of Canada. 

While the majority of this lecture did not directly relate to terraforming, by learning more about the ecosystems of Earth we can better adapt them to other planets.  If there was one thing that I took away from this, it was that managing a planet is still beyond our grasp. Only once we have successfully avoided environmental disaster on Earth should we attempt to control life elsewhere.

For this blog I read another article from Scientific American, titled “Do Three Habitable Super-Earths Really Orbit a Nearby Star?”.  The article explained that orbiting the star Gliese 667 C were found two planets.  One a large rocky “super Earth” was orbiting in the star’s habitable region, and so could have liquid water on its surface. 

Modern observations have found between three and five more planes orbiting Gliese 667 C two of them could be super-Earths orbiting in the habitable area.  Unlike our system in which smaller rocky planets orbit closer to the star, with gas and ice giants further out, the planets are huddled close to each other very close to the star.  Although this seems strange from our perspective, as more and more measurements are taken of other systems these compact orbits seem to be the norm when dealing with sun like stars.  This sort of system is referred to as dynamically packed, and now we are also finding them around M dwarfs as well, like Gleise 667 C.  This is important because it expands our idea of what a habitable solar system could look like. 

It is very hard to detect planets such as these because unlike others, which were detected by looking for transits, these were detected by looking at the wobble of the star as the planets pull it to and fro while they orbit.  With a gas giant this can be fairly simple, but when you have multiple, very small planets this because all but impossible.  Scientific American describes as “listening for faint music emerging from washes of static on a poorly tuned radio”. 

As exciting as this discovery is, doubts do still remain.  The team that interpreted the data took shortcuts that made the analysis easier, but less robust.  One of the key short cuts used, was that the team assumed the orbits to be fairly circular.  While that may seem like a wild assumption, any system that is so packed would be unstable with eccentric orbits.  This means that if the planets they thought they detected are actually there, they are likely to be much as the analysis predicted.  However, if their data was off, or if the planets are not there, then their analysis will be useless.  While that is not very comforting, the prospect of multiple super-Earths is nonetheless intriguing. 

This article really excited me, because of the possibility of other Earth like planets on a near by star.  I think that it is hard to not be optimistic with findings such as these.  Though the predictions may yet be proven wrong, the mere thought that Earth like planets are not as uncommon as previously thought is a nice one.  I really hope that the data pans out and we are able to definitively call this, but until then I will remain optimistic.

The article can be found here: http://www.scientificamerican.com/article.cfm?id=habitable-super-earths

Terraforming in the Novel “Dune”

            In Frank Herbert’s novel Dune, terraforming is a central plot point.  Though the book does bring up some of the moral dilemmas that face the issue it does not explain a terraforming process that would work as advertised in the book.  Paul’s (our protagonist’s) plan to terraform Dune involves nothing more than planting grasses and shrubs on the dunes of Arrakis.  In reality, terraforming a planet like Arrakis would take much more work than just replanting. 

            To understand the reasons for and against terraforming Arrakis, you need to understand the context.  Dune starts with some information and background on Paul’s father, Leto, then the ruler of House Atreides and how he came to posses the planet Arrakis, the setting for most of the book.  Leto was actually given Arrakis as part of a plot to kill him.  The Emperor hides his assault by using the Harkonnens to launch the actual attack; House Harkonnen and Astreides have been feuding for years.  Leto is killed, but Jessica, his lover, escapes with his son, Paul.  Jessica is one of the Bene Gesserit, a sisterhood of religious zealots who use genetic modification and breeding to create what they view as superior humans.  Living as one of the Fremen, the natives of Arrakis, Paul trains his mind and body.  Throughout the book, his actions are dictated by his lawful need to kill Harkonnen in order to avenge his father.  During his time with the Fremen Paul learns of their desire to turn their planet into a lush green paradise, the opposite of the waterless sandy desert it is.  Unfortunately, if the deserts leave then the sand worms will die out.  This is significant because the sand worms produce the drug melange, commonly known as “spice” which enhances the mental abilities of the user.  The Spacing Guild, which controls all space trade, requires spice in order to navigate space-time at faster than light speeds.  This makes spice so valuable that Arrakis, the only planet that produces spice, is the most valuable planet in the galaxy.  For this reason the emperor and the monopoly that controls all space trade are afraid of Paul terraforming the planet.  It is this leverage that Paul uses to eventually become emperor.

            The ethics of terraforming the planet Arrakis are another issue with the idea of turning the planet into a lush paradise.  The spice trade makes it complex, but when you think about the indigenous sand worms, plants and other animals the decision becomes even less clear.  If the Fremen and Paul terraform the planet they will be irreversibly changing its ecosystem and obliterating the native species.  Even beyond the natural environment, Fremen culture is centered on the desert and their desire for greener lands will be their culture’s undoing (Dune 424).  This is exacerbated by their view of water as analogous to life and as an irreplaceable object of value, “All of man’s water, ultimately, belongs to his people – to his tribe” (Dune 453).  The Fremen owe their entire culture and way of thought to the desert that they wish to destroy.

            Ethical reasons are not the only ones to stand in the way of the Fremen and Paul terraforming Arrakis. The logistics of creating a lush green paradise on a planet so barren that only the most conditioned, water-preserving beings in the galaxy can survive are almost laughably impossibly complex.  Replanting is possible to do on Earth, but even then it must be meticulously kept in order for the sand to not blow over the new foliage.  The book states that it will take at least “350 years before it [the planted forest] can be self sustaining” (Dune Appendix 1).  For fauna to be introduced it is concluded that they must cover at least three percent of the planet before photosynthesis will start producing enough oxygen for the larger insects to survive.  While it is true that adding forest will increase the amount of oxygen in the atmosphere, one must consider that the planet Arrakis has not had any meaningful photosynthesis in even the distant past.  Given this, it is unlikely that, given the relatively meager amount of oxygen each square kilometer of forest creates (Canada ENR) compared to the size of the atmosphere, there would be enough oxygen to support any insects at all even after hundreds of years with three percent of the planet forested.  All of the ideas that are proposed are good, but the logistics would be far too complex and the human resources required too much.  Another problem with the plan is that sand contains little to no nutrients, making it necessary to first grow grasses that can survive the lack of nutrients in order to create a layer of organic soil (Canada ENR).  While this is possible, it pushes the book’s estimation of 500 years total time back to a few thousand years at best.

            The terraforming of Arrakis is, while hypothetically possible, not very well explained, or thought out in the book.  Arrakis lacks water and organic soil, two things vital for forest and plants in general.  The human resources required are also fantastically huge.  These problems are overcome, but not in ways that would actually work on any scale but a geological one, and the plan would be completely foiled without an army of people planting and taking care of the forest.

Works Cited:

Canada Environment and Natural Resources. “Our Forests”  http://www.enr.gov.nt.ca/_live/pages/wpPages/Home.aspx

Herbert, Frank. Dune. 1965. New York: Berkeley, 1977.

Today I read an article in scientific American titled, “Earth’s Days are Numbered”.  The article started off with an estimate of the number of years the Earth will be able to support life as we know it; 1.75 billion.  While that number is longer than most can even comprehend, it is still less than might have been previously thought.  New models and forecasts for the sun put the Earth closer to the inside edge of the habitable zone than we previously thought.

The habitable zone is the area in which water can liquefy.  Too far away and the water will freeze, too close and it will be gas, both rendering it useless to any life we know of.  Though in a human lifetime the habitable zone seems static, over the life of a star the habitable zone can fluctuate dramatically.  As a star reaches the end of its life and starts to expand it will push the habitable zone outward as well.  The habitable zone’s current rate of movement is around one meter per year.

With this model researchers have been attempting to see planets that may be in the habitable zone of their star when we are moving out of ours.  While it is interesting to see new potential homes for Earth’s life, it has been suggested that the formula the researchers used for the model is too simple.  Without important information regarding the atmosphere and tectonic activity of the planets in question it is impossible to say if they could actually support life in the future.  Though the primary use of this model has been for extra solar planets it has also been used closer to home.  In around one billion years mars will be entering the habitable zone, if humans are still living, they may find refuge from the sun there.

Though the habitable zone may be redefined in the future, this still give us a rough idea of which planets could conceivably support Earth’s carbon based, water dependent life.  One thing that I could not help but think though is that this may be a bit too premature.  A billion and a half years is a really long time, longer than anything I can even imagine.  I find it hard to believe that there will even be humans in a billion years, and if there are they will probably not share much in common with us.  This may be pessimistic, but I think that by the time we are in need of a new planet, Humans will not be around to deliver life to it.

The article can be found here

Today I read an interesting article by Scientific American about seeing the skies of different planets, and extrasolar planetary discovery.  As it turns out, the skies of different planets (outside our solar system) are very hard to observe because all we can see is the glare from the star it orbits. 

The article begins with a brief history of our understanding and observations of extrasolar planets, and then gets into what scientists are doing today.  Because planets are so small few extrasolar ones have ever been directly observed.  How we normally detect them is by looking at minute changes in the star’s orbit.  Now though, using more modern telescopes, we have been able to detect planets just twice as massive as earth, and what is more, even look at their atmospheres.  Instead of only being able to use the star’s wobble to observe new planets we have also been looking at the apparent brightness of the star change as the planet passes in between it and Earth.  By looking at the light that shines through we can get an estimate as to what the atmosphere is made of and the planet’s density.

Though this new research had lead to the discovery of numerous potential Earth like planets it still brings up many questions.  One issue plaguing scientists currently is that on some planets, like Jupiter and Saturn temperature is not decreased with altitude, rather it increases.  Because there is no easy ways of telling which temperature gradient an extrasolar planet has it is impossible to know much more about its atmosphere, and perhaps, habitability for life. 

For now we will have to wait, but when the James Webb Space Telescope is lauched and new large sized ground telescopes become operational sometime at the end of this decade we will be able to see the planets much more directly.

I really find this article intriguing because of the sense of exploration that it captures.  Though directly imaging extrasolar planets is fantasy right now, it will be possible in the future, and I can’t wait for that to happen.

The article: http://www.nature.com/scientificamerican/journal/v309/n1/full/scientificamerican0713-40.html

My hometown of Seattle is surrounded by many geologic features.  Because of Seattle’s location on the edge of the North American plate the area has many volcanoes, mountain ranges, and is frequented by earthquakes.  The volcanoes form a line north to south, paralleling the Cascades.  The cascades, while not as large as the Rockies, are much steeper and incredibly jagged. 

                There are a total of nine volcanoes in Washington, the majority of which are stratovolcanoes.   The volcanoes, especially Mount Rainier, are iconic parts of the Washington State geography.  Mount Rainier, a large stratovolcano (14,411ft) sits due south of Seattle and is heavily glaciated with 26 major glaciers.  Mount Rainier was placed on the decade list of most deadly volcanoes on Earth, due to its explosive nature, proximity to large metropolitan areas and the high likelihood for it to produce massive ash and ice landslides, similar to those on St. Helens, but larger in size.  While it has not erupted in over one hundred years it is still active, though no indications have been seen of an imminent eruption. Mount Baker, north and slightly east of Seattle is another well known volcano, not for its size (10,781 ft), but for its extreme snowfall.  It currently holds the world record for the most snowfall in a single season, around 29 meters, which is closely followed by Mt. Rainier’s record of 28.5 meters.  There are a total of nine volcanoes in Washington, the majority of which are stratovolcanoes.

                Earthquakes are another geological hazard of the Seattle area.  In early 2001 the Nisqually earthquake hit the Puget Sound.  It measured a 6.8 and it destroyed and damaged numerous bridges and structures around Seattle.  We were very lucky that it stopped when it did the Alaskan Way viaduct, an eight lane bridge on the water front of Seattle, nearly collapsed.  State engineers did an analysis of the damage and found that collapse would have been very likely if the earthquake had lasted just 15 seconds longer.  Numerous other earthquakes hit the Seattle region, though most are smaller.

Gareth Hardwick

Blog 3

For my science fiction video I watched Star Trek.  The film starts with captain Kirk’s birth and the death of his father at the hands of Nero, the main antagonist of the film.  It then cuts to Kirk’s mischievous childhood, and eventually to him at Starfleet.  During this opening sequence we also see Spock as a child, and his anger over the abuse he receives regarding his human mother.  Once at Starfleet the tension begin Spock and Kirk begins almost immediately when Kirk cheats to pass a test that Spock designed to be impossible.  Also during the scenes at Starfleet we meet most of the crew.  The tension is carried over to the Enterprise, when Spock is made captain and Kirk second in command.  Eventually we see the reason for Nero’s appearance and also why Spock is so integral to the plot, and Nero’s eventual plan of revenge.

This movie is not particularly accurate in terms of science, beaming people to and from spaceships as well as traveling faster than the speed of light is, as far as science has seen so far, impossible.  The one interesting thing to me, was the concept of traveling back in time via going through a black hole.  This is at least hypothetically possible, though this idea it is not at all universally accepted.  Most of the science fiction elements were based on actually hypothesis, but most have been stretched to fit the Star Trek universe.  Examples of things hypothetically possible and science that has been stretched to fit are the artificial gravity and the semi sentient ship computer.  One part of science that does seem to be more accurate than the rest is the matter-anti matter engines used.  By mixing matter and anti matter you will get, hypothetically create the most efficient ship engine possible.  A great article that I used is this one at NASA.

I think that most of this film shows the nostalgia that people feel for the original Star Trek TV show.  Other parts of society that this film reflects are a love for freedom, seen especially in the opening sequence when Kirk steals a car at an early age, and for exploration, which is a major theme throughout the story.

What I really liked about the movie was seeing the whole cast of characters from Star Trek in a different light.  I was never much of a Star Trek fan, but it has permeated our culture so much that I could not help but recognize some of the characters.