Search

Some Nerd Girl

Some Like It Nerdy

Open Search
Tag

space

The Astrobiologist’s Guide to the Galaxy

In my last post, I detailed some of the hottest locations for astrobiology in our Solar System. Today, however, we’re going to be going farther afield- outside the Solar System entirely, in fact.

The discovery of exoplanets – planets that orbit other stars- has been one of the great scientific success stories of the last century. In less than 20 years, we’ve gone from a handful of early detections to literally over a thousand (plus thousands more “candidates” that are awaiting verification). Obviously, astrobiologists have been more than a little excited by this pace of discovery.

Detecting an exoplanet is no mean feat- such bodies are usually a million times dimmer than their host star, and the light of the star tends to overwhelm such faint emissions. However, several techniques have been developed to get around these limitations.

exoplanets.jpg

The earliest used, Doppler spectroscopy,takes advantage of the fact as a planet orbits a star, it “tugs” on its center of mass, causing it to “wobble” ever so slightly. The motion due to this wobble can be detected by looking for the resulting Doppler shift in the star’s spectra. However, this method is generally most effective in determining extremely large planets that orbit close to their parents stars (so called “hot Jupiters”), which are unlikely to host life.

The most successful method used to date has been transit photometry, which looks for tiny dips in the star’s light output as the planet crosses in front of it. This method does have some limitations- the star, the planet, and Earth have to be precisely aligned for the transit dip to be visible- but it’s a relatively easy signal to look for otherwise. Transit photometry has been used by a number of different observing missions, the most famous example being the spectacular planet-hunting Kepler space telescope.

A few other planets have been detected using more esoteric methods, such as gravitational microlensing or timing pulsations in stars and pulsars. A scant handful have even been directly imaged, although this only feasible if the planet is extremely large, hot, and widely separated from its host star.

Using these methods, a whole zoo of exoplanets has been detected. Most of them are likely to be uninhabitable- but let’s take a look at the ones that might be a bit more promising for seekers of extraterrestrial life.

Keplers

Kepler-296e

One of the most Earth-like planets (at least in terms of mass and theoretical surface temperatures) yet discovered, Kepler-296e is 1.75 times the size of Earth.   It orbits a red dwarf star 1089 light years away, which is part of a binary system. It is located within the habitable zone of the star, where the temperature is warm enough for water to be liquid on the surface. Kepler-296’s habitable zone is much closer than the Earth is to the sun, owing to the cooler temperature of the host star; the planet orbits its star in only 34 days.

Kepler-442b

Located 1,120 light years from Earth, Kepler-442b also orbits a cooler red dwarf star. It’s 2.34 times the size of Earth, and would have a surface gravity about 30% greater (definitely the planet to go to if you want to get a good workout).

Kepler-62e

Detected 1,200 light years from Earth in the Lyra constellation, Kepler-62e is a member of an older star system, being likely billions of years older than Earth. It is thought to have a rocky composition (like Earth’s), and computer modeling suggests the planet could be largely covered by oceans. It’s considered a strong enough candidate for habitability that it’s been targeted for observation by the SETI program.

Gliese 832 c

Gliese.jpg

One of the closest potentially habitable planets detected, Gliese 832 c is a scant 16.1 lights away. It is thought to have an extremely elliptical orbit, as planets go- that is to say, the distance from its star varies considerably. Consequently, the surface temperature may swing from -40 degrees Celsius to 7 degrees Celsius, depending on where the planet is in its orbit; on average, however, the temperature is warm enough to allow liquid water. However, it is possible the planet may have developed a dense atmosphere, leaving it in an uninhabitably hot state similar to Venus. Further observation will be required to determine how friendly to life the planet really is.

KIC 8462852

KIC.png

Unlike the other entries in this list, KIC 8462852 isn’t a planet. In fact, we’re not entirely sure what it is.   The star first became well-known when analysis of Kepler data detected a intermittent, massive drop in the amount of light produced by the star- equivalent to covering up over half the star’s visible surface- something that had never been observed before. Furthermore, no dust or debris cloud has been detected around the star.

Initially, it was thought that the dimming could be due a mass of comets pulled inwards by a passing star- and, indeed, there’s another star in the local area that could’ve done such a thing. However, an examination of historical images showed that KIC 8462852 has been dimming for the last century- far too long a timescale for the comet explanation.

Lacking any other explanation, some researchers have begun speculating that the dimming could be due to the construction of megastructures in orbit around the star- perhaps a swarm of solar power satellites to capture the maximum amount of the star’s energy (popularly referred to as a Dyson sphere or Dyson swarm).

Admittedly, there are some problems with the aliens-did-it hypothesis- the laws of thermodynamics dictate that such structures would generate a large and detectable quantity of waste heat, which has yet to be observed. Observing campaigns by SETI also haven’t turned up any signs of intelligent life. Nonetheless, the sheer weirdness of the system means it will likely be a target of investigation for the foreseeable future. Whatever’s going on out there, it’s not like anything we’ve seen before.

Conclusion

These are just a handful of the potential living worlds that might be found throughout our galaxy. Undoubtedly more will be detected by upcoming missions, such as the James Webb Space Telescope, PLATO, and Kepler’s successor TESS. Get your travel itineraries ready- because the list of possible cosmic vacation hotspots is only going to keep growing!

TessTessa is a 28 year old PhD student, and perhaps the world’s only queer trans astrobiologist. A nerd going way back, her interests include science fiction, space exploration, sustainability, science communication, and feminism and gender. Her hobbies also include horseback riding, playing the flute, social dancing, knitting, and occasional attempts at writing fiction. She currently resides in Tempe, AZ with her even nerdier fiancee and a mastiff mix who thinks he’s a lapdog. She tweets occasionally @spacermase.

 

0

The Astrobiologist’s Guide to Life, the Solar System and Everything

As I’ve mentioned previously, my career is based around looking for alien life in the universe. Naturally, this brings up the very pertinent question of “Where exactly does one look for aliens?”

The answer, surprisingly, is “pretty much all over the place.” And with good reason – here on Earth, living organisms have been found in some of the most seemingly inhospitable places, which suggests that life is, above all, tenacious in the extreme.

Where to begin, then? Why not in our own backyard? As it turns out, there are more than a few places in our own Solar System that might harbor life. So, without further adieu, let’s take a guided tour of the Solar System’s hottest real estate, moving from the inner planets outwards.

Venus

Venus copy.png

Venus may seem like a surprising candidate – the surface is hot enough to melt lead, the atmospheric pressure is crushing, and it rains sulfuric acid. But Venus was not always so grim. It is thought that it may have had oceans for the first two billion years of its history, before the growing intensity of the young sun triggered a runaway greenhouse effect that boiled them off. Life may have been able to get a toehold in these early seas, as it did on Earth.

But where could such life have fled to under the onslaught of rising temperatures? Curiously, it turns out that while the surface may be utterly inhabitable, at ~50km above the ground, the atmosphere of Venus is remarkably Earth-like in temperature and pressure. It’s still fairly acidic, there’s no oxygen, and it’s still on the warm side, but there are organisms on Earth that will quite happily live in similar conditions. UV radiation would be a problem – however, interestingly enough, cylcooctasulfate – a sulfur compound that absorbs UV rays and re-emits them as visible light, and that’s used by terrestrial microbes as “sun screen” – is found in the Venusian atmosphere at an altitude of 50km.

Earth

Earth.png

No, I’m not suggesting Earth’s been invaded – I’m instead referring to the idea of the shadow biosphere. The basic premise of the shadow biosphere is that we assume that all life on Earth is biochemically similar to us (e.g., it uses the same types of proteins and DNA, same chemical reactions, and so forth), and therefore we would fail to detect microbes that used radically different biochemistry. The microbes wouldn’t be “aliens”, per se, as it’s assumed that they would’ve evolved here on Earth – but such a finding would still be incredibly significant, as it would suggest that life may developed independently on Earth, multiple times.

Supporters of the shadow biosphere hypothesis point to the fact that the vast majority of microbes can’t actually be cultured in a laboratory, and as a result, we know very little about them. There have been searches for “weird life”, including, most notoriously, GFAJ-1. GFAJ-1 was initially reported to use arsenic in the construction of its DNA (as opposed to phosphorus, which is what all known life uses instead). However, after its discovery was announced, further experimentation couldn’t detect the presence of arsenic in its DNA, and biochemical modeling suggested that DNA using arsenic wouldn’t actually be chemically stable. The search goes on.

Mars

Mars

This list obviously wouldn’t be complete without everyone’s favorite red planet, Mars. Mars has long held a fascination, in part due to early observations of channels or canals on the surface (these were later revealed to be the result of an optical illusion). As it turns out, such a reputation might be warranted – Mars is the most Earth-like planet in our Solar System, and shows evidence of being a much warmer, wetter planet in its past (most notably, the presence of dry river networks and lake beds). In the present day, there also appears to be seasonal flows of liquid brine or extremely salty water, most likely the result of salts absorbing water vapor from the atmosphere.

As I mentioned in my previous essay, methane has also been detected in the Martian atmosphere. Since methane isn’t chemically stable under Martian conditions, something must actively producing it. Stranger yet, the production appears to be sporadic, suggesting that this is the result of an active process. While there are purely geological processes that can produce methane, here on Earth, the vast majority of methane is produced by microbes, which obviously raises suspicions.

It’s unlikely the Martian microbes – if they exist – are living on the surface, due to the high flux of radiation. Instead, they’ll most likely be found in deep subsurface habitats or aquifers, or potentially underneath the polar ice caps. Future missions to Mars (notably the ESA’s ExoMars and NASA’s Mars 2020 Rover) will hopefully give us better answers to the age old question of life on Mars.

Europa

Europa.png

Moving into the outer Solar System, Europa is one of the four major moons of Jupiter, and is covered entirely by a thick layer of ice. It’s been a target of great interest to astrobiologists since the data from the Voyager missions suggested the presence of a vast ocean underneath the ice layer. The thickness of the ice shell and the depth of the ocean is subject to debate, but it’s thought that it could be as much as 100 miles deep, and encompass a volume of water twice the size of all of Earth’s oceans. Given the importance of liquid water to life as we know it, this obviously makes it a potential candidate for habitability.

Due to the complete absence of sunlight underneath the ice shell, if there’s life on Europa, it’s probably clustered around hydrothermal vents, much like the vent ecosystems seen on ocean floors here on Earth. These vents are driven by volcanic heating driven by the intense tidal forces of Jupiter, which also keeps the ocean from freezing, and is also most likely responsible for the alleged plumes of water erupting from the surface.

Several missions are planned to study Europa – ESA’s Jupiter Icy Moons Explorer and NASA’s Europa Multi-Flyby Mission, which will hopefully be able to measure the thickness of the ice shell, gather more data on the chemical composition of the surface, and sample the surface plumes (if they exist). Proposals have been circulating to actually drill down and explore the ocean, but such a mission is a while off.

Enceladus

Enceladus.png

Similar to Europa, Enceladus is an ice covered moon orbiting Saturn. It features extensive plumes of water erupting from its southern hemisphere, thought to originate in a subsurface ocean. The exact mechanisms driving the plumes hasn’t been determined, but there’s likely hydrothermal activity in play. Since the plumes are so extensive, the Cassini mission in orbit around Saturn has been able to conveniently sample some of the erupted material, and discovered that it has a high salt content (suggesting hydrothermal activity) and traces of simple organic compounds. Given the presence of organics, liquid water, and a likely energy source, Enceladus has become a hot topic amongst astrobiologists, and will hopefully be the target of future exploration

Titan

Titan.png

Another moon of Saturn, Titan is the second largest moon in the Solar System, and the only one with a dense atmosphere. The atmosphere is made up of a mixture of nitrogen, methane, and a mixture of organic compounds. Titan is a chilly -355 degrees Fahrenheit, so cold that methane is liquid at the surface. In fact, the most interesting thing about Titan is that liquid methane takes the place of water – there are rivers and lakes of the stuff.

Consequently, unlike the other worlds we’ve looked at, if there’s life on Titan, it’s very different from the water-based life we’re familiar with. Potential biochemical pathways have been identified for the Titanian atmosphere, and, interestingly enough, some of the features in Titan’s atmospheric composition would be consistent with presence of metabolizing organisms. Nonetheless, life on Titan remains a much more speculative topic, and will require further exploration of this mysterious, haze shrouded moon.

Conclusion

While Earth may be the most habitable world in our Solar System, it isn’t the only place life might have evolved. No alien life has been conclusively detected, but the hunt is on. The most exciting aspect of this search is that if life evolved independently, multiple times within the same solar system, it suggests that the emergence of life is a common event.

In other words, if we discover that our Solar System is teeming with life, it’s likely that so is the rest of the galaxy.

Tess

Tessa is a 28 year old PhD student, and perhaps the world’s only queer trans astrobiologist. A nerd going way back, her interests include science fiction, space exploration, sustainability, science communication, and feminism and gender. Her hobbies also include horseback riding, playing the flute, social dancing, knitting, and occasional attempts at writing fiction. She currently resides in Tempe, AZ with her even nerdier fiancee and a mastiff mix who thinks he’s a lapdog. She tweets occasionally @spacermase.

2

I Hunt Aliens for a Living

When people find out that I’m an astrobiologist – that is, my work concerns the search for life on other planets, amongst other things- invariably, the first question is, “Have you found any yet?”

So, to start, I’d like to say for the record, that no, I haven’t (believe me, you would have heard about it if I had). But while that goal remains unattained, astrobiologists have still made astounding discoveries about life in the universe – and the finding of truly alien life may not be that far off.

I think the reason people find my field of research so fascinating is because it tackles some very foundational questions. How did life originate? Under what conditions can it survive? Where else might we find it? And what might it look like when we do? Because of the scale of these questions, astrobiology isn’t really a single field, per se – but rather a collections of many different disciplines (including, but not limited to, astronomy, geology, chemistry, biology, and planetary science), all trying to come up with answers.

Moon
Strap in for a good ol’ fashion existential crisis!

In order to determine the likelihood of finding life elsewhere in the universe, we first must know how easy or difficult it is for life to emerge in the first place. This is the realm of the prebiotic chemists, who focus on how living systems can develop from simple chemistry (sometimes poetically referred to as abiogenesis). There are different theories as to how this happened – some scientists suggest that RNA, a molecule similar to DNA that has the capability to reproduce itself may have been the forerunner to life as we know it; others suggest that metabolic processes, or the creation of simple bubble-like “protocells” set the stage for life. It should be noted that these theories are not necessarily mutually exclusive – it has been suggested that life may have originated independently multiple times on Earth, competed and merged with each other, and finally gave rise to the biosphere we know today.

Difference-DNA-and-RNA.jpg

I should note that a general assumption about life in the universe is that it’ll most likely be similar to us, biochemically speaking. The foundations of Earth biochemistry are carbon (due to the fact that it can easily form complex molecules) and water (which is particularly good at dissolving molecules, and appears to be abundant through the universe). The latter was considered so key to life as we know it that, for a period of time, the motto of NASA’s astrobiology program was “Follow the Water” (this is also why there’s so much buzz whenever NASA announces the detection of liquid water elsewhere in our solar system). With that said, more exotic biochemistries – using silicon instead of carbon, for example, or using ammonia or methane instead of water – have also been proposed.

In addition to how life comes into being, we also must know how many places are available for it to live. One approach to this question is studying the abundance of habitable planets in the universe. Exoplanets – planets found around stars other than our sun- have been discovered to be staggeringly common. The Kepler space telescope mission, in particular, has found dozens of potentially Earth-like worlds, many located in the “Goldilocks zone” of their main star (where the temperature is “just right” for liquid water to exist on the surface).

GZone.png

We don’t know necessarily know if these planets are actually inhabitable or not (though we hope to answer that with future missions, such as the James Webb Space Telescope and Transiting Exoplanet Survey Satellite; I’m particularly fond of the latter since it shares my name), but these early findings are certainly promising.

Another angle on the question of habitability is studying the conditions on which life can survive – especially in environments that seem extreme and inhospitable to us. As it turns out, life is extraordinarily hardy, with organisms, known as extremophiles, making their homes in even incredibly harsh surroundings. From microbes living in the superheated water of hydrothermal systems to radiation-eating fungi discovered in the ruins of Chernobyl , it appears that life is amazingly adaptable. While most extremophiles are microbes, there are some more complex organisms that hold this distinction as well – my particular favorite being the iceworm, a glacier-dwelling invertebrate that is so well adapted to the cold that it will literally melt if its temperature is raised too high above freezing.

ice-worm_1813.jpg

So, having established how life might originate and where it might survive, the next question is how might we detect it? This brings us to one of the primary areas of research in astrobiology – the identification and detection of biosignatures. Biosignatures are simply the chemical and physical traces left by living systems on their environment. A classic example is the presence of both methane and oxygen in the Earth’s atmosphere – since methane isn’t chemically stable in those conditions, some process must actively be producing it (incidentally, methane isn’t stable on Mars, either – which is why there was such excitement when very low levels of it were detected by the Curiosity mission). Biosignatures can also include microfossils or other geological traces left by microbes, and spectral lines in the light reflected off a planet indicating the presence of chlorophyll.

Nemesis_tricorder
I am still waiting for my engineering counterparts to hook me up with one of these.

Related to biosignatures is probably the most famous aspect of astrobiology – the search for technosignatures. As the name suggests, these are indicators of the presence of a technological civilization. SETI, the Search for Extraterrestrial Intelligence, is the most well known effort to locate signs of an advanced aliens, but it is not the only one- there also astrobiologists keeping their eyes peeled for everything from signs of astroengineering (constructions the size of stars) to potentially looking for the lights of alien cities in the spectral signatures of planets. A find of this sort is the holy grail of astrobiology – after all, as exciting as an alien microbe might be, we’rd really prefer something we could talk to.   It’s worth noting, though, it is statistically unlikely that any other alien civilization is at the same technology level as us, and may be much further advanced on the Kardashev scale, so they may not be as interested in what we have to say.

Are we alone? Where did we come from? These are just some of the questions astrobiologists hope to answer. And, even better, you can help the astrobiology community answer them, too! The field has been a pioneer in the use of citizen science – recruiting assistance from everyday people.   Projects include SETI@Home (a screensaver that uses your computer’s idle processing power to search for signals in SETI radio data) and Planet Hunters (a website where users can help detect planets around other stars).

PlanetHunters
Be part of the search!

So, if you find the search for life in the universe as thrilling and fascinating as I do, then feel free to join in the fun! Who knows- you might just find help us find something.

And I’d finally have a good answer for “Have you found any yet?”

Tess

Tessa is a 28 year old PhD student, and perhaps the world’s only queer trans astrobiologist. A nerd going way back, her interests include science fiction, space exploration, sustainability, science communication, and feminism and gender. Her hobbies also include horseback riding, playing the flute, social dancing, knitting, and occasional attempts at writing fiction. She currently resides in Tempe, AZ with her even nerdier fiancee and a mastiff mix who thinks he’s a lapdog. She tweets occasionally @spacermase.

1

I am not your Slave Leia

You see it at every comic book convention; multitudes of women (and a few lovely men!) dressed as ‘slave Leia.’ And when I look at them I think: Good for them!

People have the right to wear whatever the hell they want. But I personally will not wear that outfit. Because I am not slave Leia.

Slave-Leia-star-wars-33821458-3190-2540
Only Carrie Fisher can somehow make this classy.

I think Leia is a great character. She’s a strong woman. She fights with the Rebel Alliance despite being an actual princess (compare her to most of the Disney princesses). She risks her life to get the plans for the Death Star. She withstands torture at the hands of Darth Vader and the Imperial Forces. She watches her home planet of Alderaan get destroyed. And STILL doesn’t give up the information they want while continuing to maintain her strength and dignity.

LeiaandBlaster
She will wreck you.

In short, she is a BAMF. And this is all still in the very first movie. Nevermind that she grabs a gun and tries to escape from the Death Star as soon as she gets the first opportunity. Nevermind that she has a sarcastic attitude and a comeback to every one liner thrown at her by Han Solo. And also nevermind that she somehow resisted jumping that dude’s bones for three movies.

HanWithBlaster
Alternate version of how Han managed to score with Leia?

She rocks.

But seriously, slave Leia? That is Leia at her weakest. She has again been captured. She is forced into a humiliating outfit that represents her captivity. She is wearing a literal chain around her neck like some kind of animal. She is forced to serve Jabba the Hutt who is repulsive in every sense of the word.

Now I am not trying to take away from her. She kills Jabba with that fucking chain. She breaks free of those chains and operates a cannon in that outfit. She helps Luke and Han escape. But still….slave Leia?

Slave-Leia-Fights
I’d be pissed too if someone made me wear that.

I am not slave Leia. If I were to cosplay Leia I would go as some other version of her. Almost all of them are better than her as a slave.

endor001
Even sexy mechanic Leia.

I am Boushh Leia. I am the Leia that willingly enters Jabba the Hutt’s den, risking my life to help my love. I am the Leia that convinces my enemies that I could, single-handedly, capture Chewbacca. I am the Leia that pulls a thermal detonator on a room full of people to settle my negotiations. I am the Leia that unfreezes Han from his carbonite prison.

Boushh-06222015
If princessing didn’t work out for her, being a bounty hunter probably would have!

If I am going to dress up as Leia, I am not going to be slave Leia.

MaurnasMaurnas is the barely anonymous alias of a reclusive Floridian fangirl. She has an alleged humor blog at cursitivity.WordPress.com and can also be found at maurnas@cursitivity on Twitter. She writes almost as much as she reads but has done nothing with her debatable talents thus far other than all the blogging and tweeting and writing.

2

Blog at WordPress.com.

Up ↑