Sometime in the early 2000s, this place was still a speck of data in some astronomers brain. The announcement of a system of seven earth-sized planets was pretty big. The further revelation of three of those worlds sitting within their stars habitable zone was the icing on the cake.
As the first intelligent explorers approach TRAPPIST-1e, we present to you these images: the culmination of decades of waiting, hoping that return transmissions from the TRAPPIST-1 mission wouldn’t get lost in interstellar space. There were those who worried that anything beamed back by the missions wouldn’t even make it out of the system. TRAPPIST-1 is a red dwarf star: a tiny relic of a thing but incredibly ancient. Age estimates range from 8 to 12 billion years old. Red dwarf stars tend to be nasty little suckers, and TRAPPIST-1 is no exception. Extreme solar flare activity sometimes hits the system, as the parent star has a tantrum. Communication from the system is nothing short of a miracle. Nevertheless, here are some of the better images we’ve managed to glean from the stream of data being sent back. Thirty nine years worth. Thirty nine years of waiting.
Approach: A New Red Planet
The very first direct images of TRAPPIST-1 and it’s rocky retinue were messy little blobs of pixels.
Of course, many exoplanets (and exomoons) had been imaged directly using a variety of techniques. The use of coronagraphs to scrape together images from points of light across impossible distances was revealing new vistas for a long time. The following image was taken all the way back in 2004:
A disc of debris around the red dwarf star AU Microscopii. Image: Hubblesite.org
Of course, progress marched on, and as missions approached the system the world waited for new images. A first blurry image sped across the galactic neighbourhood:
This image was a first test. As the mission approached the system, we began seeing more. High quality imaging was held off until final approach, in the interests of energy efficiency.
An infrared and monochromatic direct light image, taken from a distance of approximately 11 AU. Images: Ben Roberts
TRAPPIST-1e was waiting for us.
Imaging of exoplanets is explored in a new video, presenting the concept of coronagraphy. Help astrobiology reach the world (this and others) by checking it out. Subscribe and share if you like.
This post is the first of a series taking us on a trip to a real alien world, and speculating on just what it could be like, using real world astrobiology. I hope you like it!
I’ve been working on some more astrobiology art. It’s taken on a life of its own, and I have to say, I’m paying more attention to these images than my YouTube channel!
I’ve been enamoured lately of dead or dying worlds. A recent video on my channel talked about the amazing possibility of limestone fragments orbiting the white dwarf star SDSSJ1043+0855. Ever since reading of this it’s captured my imagination. The notion that life has existed long ago, possibly before life began on earth bears thinking about.
Limestone is a mineral produced primarily by organisms which produce shells, using a matrix that incorporates calcium carbonate. In the early days of multicellularity, as the predator-prey paradigm took hold of Darwinian evolution, an ancestor of today’s molluscs discovered how to make use of an upsurge in calcium levels in the oceans. It used it to produce a protective suit of armour. This trick was so successful that molluscs became incredibly abundant. So abundant, in fact, that their remains ended up as vast deposits of limestone.
To the present day.
Using spectroscopy, the three elements that comprise calcium carbonate: carbon, oxygen and calcium have been detected in the upper atmosphere of this particular white dwarf. By themselves they aren’t a smoking gun. It’s also fair to point out that limestone can form abiotically. Limestone deposits in subterranean caves are one example. However, the vast majority of limestone on earth is biologically produced.
The “limestone” orbiting this star is believed to be embedded in the fragments of a large rocky object. We know nothing about this world, only that it probably existed and (possibly) limestone comprised part of it. Is it a fossil, spotted across the light years by modern humans? How long ago did this world harbour life? White dwarf stars (which aren’t technically stars! Find out why here) have been discovered which are nearly as old as the universe.
Earth is 4.6 billion years old. What of the world currently being torn up by the immense gravity of this white dwarf?
It would be interesting to look forward and see how our own world eventually will die. For now, this white dwarf star and it’s companions are a way to look ahead at what may befall us. It’s believed that eventually the earth will become incapable of supporting life, as the sun begins to undergo senescence billions of years from now. What iterations will the terrestrial biosphere take over such a vast stretch of time? Will life start over? Are these “fossil” fragments within this unnamed rocky world pieces of its last ecosystems?
A comment on a facebook post I put up a few days ago got me thinking about habitability. Moreover, I got to thinking about the parameters of habitability.
We think that life here on earth is fragile, holding on to a thin silicate crust within a fairly narrow range of temperatures and conditions. For the most part it is. Life needs a fairly stable environment in order to keep on keeping on. However, there are plenty of examples of oddballs: extremophiles, that seem to do quite well in some pretty horrible places. The recent discovery of Antarctic microbes that derive energy from air itselfexpands the catalogue of organisms that could have analogues on other worlds.
Now, extremophiles do well in extreme environments. No brainer there, and there is no shortage of extreme environments in our solar system alone.
Venus is an example, and a good one. Analogous to Earth in size, density, gravity and composition, it differs markedly in others. No magnetic field, no water (at 0.002% of the atmosphere not worth mentioning), surface temperatures that melt lead, and atmospheric pressure ninety two times what we’re used to here. It’s horrible.
No plate tectonics. On earth we slowly sail about the globe on slabs of continental crust, which happen to be more buoyant than the thicker, denser oceanic crust. Driven by convection of magma in the mantle, crust is slowly pushed hither and thither by tectonic processes such as seafloor spreading.
To understand what this is, imagine a pot of something thick like soup or porridge on a stove top. As the contents of the pot heat up they begin to stir. Have you ever noticed when this begins to happen that as the surface begins bubbling the top layer is forced aside as new material wells up from below? This is seafloor spreading in a nutshell. Magma from within the earth wells up, heated by a radioactive core, and pushes the seafloor aside as it breaks through, forming new crust. The continental plates, perched atop this moving crust, slowly journey across the planet.
Why is this so important to life on Earth? Because our planets interior is so hot, plate tectonics (along with volcanism) is the primary means by which excess heat is released over time. If this didn’t happen, well, you wouldn’t be here reading this and there would be two Venuses in our solar system instead of one.
For reasons unknown, Venus shut down. It’s core stopped spinning, it’s magnetic field dwindled to nothing and radiation from the sun began a process of stripping the planet of water. Water is a true miracle ingredient. Not only is it a solvent for biological processes, it’s also a lubricant for plate tectonics. Venus seized up and overheated: exactly like a car without oil will do.
A stagnant lid world is one which has no plate tectonics. Climate is seriously affected by such a situation. With no means of escape, heat builds up within, and eventually it becomes an exo-Venus: scorching hot.
Researchers looking at the issue of habitability on exoplanets have looked at the implications of a stagnant lid regime for the possibility of life. Whilst it would obviously be different to life on earth, other factors can lend habitability to a planet.
These other possibilities are exciting indeed. I’ve been exploring astrobiology through images, producing a bunch of pictures. They will be appearing over the next few posts, so I hope you enjoy them. They’re doing well on Instagram!
Thank you for reading the ramblings of a space nerd. The universe is just too intetesting to ignore.
It’s been estimated that a good percentage of planets beyond our solar system may be water worlds.
We here on mother Earth like to think of our blue green marble as a water world. Indeed it is watery, and water is pretty much the reason anything lives here at all. That’s why astrobiologists naturally seek signs of water on exoplanets. “Follow the Water” is a central tenet in the search for extraterrestrial life.
But compared to some worlds, earth really isn’t that waterlogged at all. It’s 0.002 percent water by mass. Only a tiny fraction of that water is available to terrestrial life. That water which isn’t directly involved in biological processes is linked to them, linking life to the planet via seasons and climate.
Some exoplanets are believed to be up to fifty percent water! These are true ocean worlds. To date, up to thirty five percent of exoplanets larger than may be covered by vast layers of water that may or may not harbour life. The jury is well out on that, but the idea is intriguing (and tempting) as the traditional definition of habitable zones is being stretched and reinterpreted.
For now, we have only our imaginations with which to explore these worlds…
The universe is turning out to be a more interesting place with each passing day for me. It’s not all about reading research articles and trawling the internet for interesting news in the vast field that is astrobiology.
I’ve been working on images related to various themes in astrobiology. This field really is a playground for the imagination, and it has something for everyone….
Something really special here: possible traces of limestones found in the fragments of objects orbiting a nearby white dwarf star…
Differing definitions of the Habitable Zone further push the limits of life in the universe..
Svante Arhenius, a swedish chemist and early pioneer of the theory of panspermia..
Ruminations on the code (codes?) that make life possible. How many languages does life have in the Universe?
Does the chemical rich, pitch black seabed of Europa host life? Does that of Enceladus?
The first image I created. I hope you’ve like these. There will be more! By the way, the background for this image comes from an online simulator called Goldilocks, by Jan Willem Tulp. His work can be found here. It’s really cool.
It’s a story that began 20000 years ago, and has been waiting for you. Like something out of a “Star Trek” episode. The vista before you hangs in the black like a portal into the fiery underbelly of all that’s good in the Universe.
“Star Trek” You remember it now. The Battle of Wolf-359. It was a classic episode, in which a tattered human military force took on a vastly superior foe: the Borg. These creatures were bloodless and implacable. Truly unsettling bad guys.
This monster is just as unsettling. Wolf-Rayet-124 is real. It’s huge. You’ve come a long way to encounter it. A small fleet of drone-sats has been dispatched to get up close and personal with this Wolf-Rayet star, to see how extreme extreme sports can get.
As soon as humans got comfortable in space and started calling all kinds of dark corners and odd rocks home they were up to their usual mischief. As soon as all the laws were decreed and the soapboxes were all put away, humans got back to the serious business of finding new and bizarre ways to enjoy themselves.
Space tourism didn’t become big business. It became exponentially big business. Extreme sports fans weren’t interested in scuba diving with great white sharks anymore, or parachuting.
Ha! You recall the stories. The One-G-ers were those quaint old extreme sportsters who couldn’t let go of old mother earth. Most of them were toothless and half nuts decades ago, but they still harped on about climbing Mount Everest or wrestling crocodiles.
You look upon Wolf-124, blazing with a luminosity several million times greater than Earths sun back home. Wolf-124 is huge. How huge? These kinds of stars are rare. Of the millions of stars known to humanity only around 500 Wolf-Rayet stars are known to exist in this galaxy.
Wolf-Rayet stars are thought to be the powerhouses driving many planetary nebula or stellar nurseries. How does this work?
Your little drone sats are tasting the cloud of ionised gas and interstellar gunk that swirls around the star. This cloud is nearly 6 light years across; a dusty miasma flung outwards by the intense solar winds radiating from the star within. From your vantage point out here, looking down into this slow maelstrom you see chunks of the star heading outward. Earth sized pieces of WR-124 soar through the cloud like the volcanic rage of a demon tearing itself apart.
You write that last line down. The tourists will love it.
Sometime around 20000 years ago, when human beings were first discovering Europe WR-124 began tearing itself apart. Scientists never really ascertained why, but it’s made for some great observations over the years. Tourists will love this. You got here first, to set up the first fleet of solar sailing yachts. The winds from the star crack along at 1600 km per second, fast enough to twist the most iron stomachs.
These stars have unusual emission spectra. Many of the space tourists won’t care what this is, but there’s always someone in every group who just has to understand what they’re leaping into. Fair enough. What it means is that like any other star a Wolf-Rayet star burns up fuel. Our star, a relatively youthful star somewhere near middle age, is still burning hydrogen via the process of stellar fusion. As a star ages it’s supply of hydrogen becomes depleted, and it must burn heavier elements in order to survive.Wolf-Rayet stars are often seen to have high levels of quite heavy elements or “metals” such as carbon or nitrogen in their upper atmosphere. This is due to nearly complete depletion of hydrogen fuel so as a result heavier elements are being used up.
What does this have to do with spectra? Well, as elements transition from higher to lower energy states, ie when they’re being burned up inside a star, photons of particular wavelenghts are given off. It’s possible to tell just by analysing the wavelengths of light radiating from a star (it’s emmision spectra) what’s going on in and immediately around the star. This is why scientists know WR stars are old, and what they’re burning off in place of hydrogen. It’s also the reason they can infer the presence of extreme solar winds. The luminosity and heat given off by a WR star is extreme. At it’s surface a WR star can reach temperatures of between 30000 and 200000 Kelvin; hotter by far than most other stars. Such radiative pressure literally manifests as a “wind”, with the abilty to exert pressure on objects, such as solar sails!
Most of the drone sats are keeping a safe distance from WR-124. This might just be an imaginary blog post, but you have imaginary operating costs, you know?
So you’ve staked your claim here. Now, all that’s left to do is wait for the money to fly in!
Still, you’re thinking of your next venture. There’s an exoplanet out there somewhere: HD 189733B where it rains glass! Now that sounds like fun…..
While you’re here, join me on the AstroBiological YouTube channel. I’m hard at work sprucing it up. What do you think of this intro sequence?
One last thing!
Hop onto WeCreateEdu: an online community for educational you tubers. There is a galaxy of stuff to learn and explore here. Very much worth a look: