Earlier this year in January we talked about the European Space Agency’s ambitious plans to land a spacecraft on a Comet rocketing through space. The spacecraft, named Rosetta, orbited the sun in hibernation mode until a lucky winner from here on Earth got to issue her, her 7am wake-up call. After that, it was time to get to work.
After ten long years, a billion euros, and a whole lot of nail-biting and prayer, Rosetta is ready to “rock” and roll. (Heh, asteroid puns…) So what exactly was the ESA’s plan for Rosetta? First and foremost to dock with the comet known as 67P/Churyumov-Gerasimenko. But that begs the bigger question, why?
Mainly because it will be the first time a project like this has been attempted. It will give us a much clearer understanding of how comets are formed, what they’re made of, and quite possibly, whether or not they contain the necessary building blocks of life. Namely carbon, bio-organisms, and of course, water.
As of the time of this writing, August 6th, 2014, Rosetta has made contact right on schedule. To read our original report on Rosetta from back in January and get some information on the differences between celestial bodies in our solar system check out that entry here (Earth To Rosetta, Time To Wake Up).
Now without further ado, let’s see what a comet looks like up close.
“Rubber-Ducky, You’re The One…”
Coined, it seems, by the media as a “Rubber-Duck” shaped object, 67P/Churyumov is an oddly shaped little fella. Well…little is sort of a relative term when talking about massive celestial objects like this. 67P is what’s considered to be a contact binary. This means that there are actually two asteroids sort of fused together that formed their shape.
This is caused due to gravity. The two objects are attracted to one another (love at first sight) until the point where they touch. Since space is cold and comets are essentially (assumptively for now anyway) mainly composed of ice and rock, a fusion takes place and the two are joined together into one solid object.
Today, after a seven minute thrust period, Rosetta was able to beam back images of the comet to Earth, (See a slideshow presented by the ESA here) in Darmstadt, Germany. “This is your only chance to have a rendezvous with a comet,” said Jean-Jacques Dordain. He is the director-general of the ESA, and he’s right. This mission has been up in the air, literally, since March of 2004 when it was launched from French Guinea. Heck, 67P wasn’t even their original target! (Read our last article from January for more)
Now, Rosetta is orbiting the object at a safe distance of 100km (around 62 miles) away. The probe caught up with 67P as it made the last leg of its 6 and a half year journey toward the sun. The comet was moving at 55,000 km/h (roughly 34,000 MPH), which made the requirements leading up to this historic event all the more significant.
What were those requirements you ask? Let’s talk briefly about those next.
“I’m Getting Kinda Dizzy here…”
For ten years Rosetta made its lazy loop cycle around the sun, gathering energy on its massive solar array to be able to carry out its duties. Every time it made one of these loops it built up speed. Finally, after about a half dozen or so spins around the sun it was ready to wake up and take off. It should be. It only had to log 6.4 billion kilometers in travel time (that’s about 4 billion miles) to get to that point.
Not only did Rosetta have to be able to catch the comet, it also had to have enough power to analyze it when it got there. After all, it wouldn’t make much sense to have a billion dollar piece of tech just wave at the thing. Its solar array had to be able to garner enough energy to re-power the thrusters once the comet’s trajectory was in line.
The good news? Everything went off without a hitch, and the ESA couldn’t be more tickled. So now what? Well Rosetta is going to ride in tandem with the comet for a while and record information on it, including temperature, size, composition, and much, much more.
So what have they discovered so far about 67P? Quite a bit actually. Let’s talk about that next. We’ll start with what we already knew about this heavenly body in the next section and finish the last segment off with a quick fact sheet. (And I do mean facts, this isn’t FOX “News”…)
My…What Big Craters You Have
On September 11th, 1969 at the Alma-Ata Astrophysical Institute, researcher Svetlana Ivanova Gerasimenko was analyzing photographic plates of the comet 32P/Comas Solá when fellow astronomer Klim Ivanovych Churyumov decided to join her. He spotted a comet-like object near the edge of the plate but this was just blown off at the time as being part of Comas Solá.
That’s when Churyumov returned home to his institute in Kiev, Ukraine. He examined all of the plates under closer scrutiny and made a strange discovery. The object in the photograph that he had initially wrote off as part of Comas Solá was actually a different object. How did he know this? It was about 1.8 degrees off of the expected position, which meant that Comas Solá was actually way bigger than they thought, or they were looking at a different object altogether.
What’s he holding up there you ask? A photographic plate. What’s a photographic plate? It’s the original method for capturing images of space. Plates predated film as the primary medium for capturing high resolution images of the stars above. Such plates respond to ~2% of light received and were made of glass, which meant that they were far more stable than film. Film had a tendency to bend and distort images captured of light, and when you’re trying to target exactlywhere an object is millions of miles away, the smallest variation in the photograph can throw your calculations off by thousands of miles.
Photographic plates have been largely replaced by digital imaging which is even more accurate and with far higher resolutions, but it is a little piece of nostalgia for some. Several archives have been established solely for the preservation of this outdated, but still very cool technology.
For the sake of time constraints we’ll talk more about photographic plates I’m sure in the future, for now though, we need to head back to Churyumov and Geramisenko. They discovered that 67Ps perihelion distance was about 2.7 AU (about 2.5 million miles) but a close encounter with Jupiter had altered its orbit slightly, putting it at around 1.9 AU from perihelion, where it remains today.
I know, I know, what’s perihelion…
Why, it’s the opposite of aphelion of course!
Perihelion means the object will be closest in its orbit to the sun. Perihelion for comet 67P will be reached in 2015, but it doesn’t necessarily have to be super close to the sun in order for researchers to gather the information on it they’re looking for.
The whole goal of Rosetta is to gather information on the comet as it closes in on its closest orbit to the sun. Why you ask? Because once it reaches flanking position to our star it will begin to heat up. Once it heats up it will begin to display its tail, or coma. Once this happens the real fun begins.
Don’t Let ‘Em See You Sweat
“After ten years, five months, and four days travelling towards our destination, looping around the sun five times, we are delighted to announce that finally ‘we are here’.” Said Jean-Jacques this morning in a statement issued to the press. Talk about dedication. So what have they discovered?
Well first off, 67P/Churyumov looks as though it has been through a war. The surface is littered with craters, hills, and steep cliffs. At over two miles wide and two and a half miles across it’s got quite a few features to explore. Naturally, this is extremely exciting to astronomers (and space geeks like me…respectfully) because it offers the first ever up close and personal imagery taken of a comet.
Rosetta and “Chury” now reside somewhere between the orbits of Mars and Jupiter, around 250 million miles away. Now it’s important to note that there havebeen other missions performed by various space agencies in which flybys of comets have been accomplished. The difference with this mission is the longevity, and not just the amount of time it took to get us there.
Rosetta will stalk the comet for around a year, mapping and measuring its changes as 67P is affected by solar radiation from the sun. Over ten thruster maneuvers have been performed since May just to get the comet and the satellite in alignment with one another. Had any of those delicate thruster tasks failed, the entire mission would have been scrubbed.
Above we talked about “Contact Binaries”. That isn’t the only possibility to describe 67Ps odd shape and size. Another theory is that as it passed by the sun in previous orbits, ice melted away from the comet giving it it’s strange “Rubber-duck” shape. Another possibility could have been from collisions.
One thing is certain though, the comet is a sweaty one. Even at its current distance from the sun it’s beginning to show signs of transpiration. Comet 67P is giving off about 300 ML of water per second as it rockets through space. But Rosetta isn’t just checking to see how sweaty 67P gets after a workout; it’s actually scanning the comet searching for a viable landing site.
For what you ask? For Philae of course!
Later this year, after gravitational forces have been properly measured and a landing site has been determined, in November, Philae is slated to detach from Rosetta and harpoon itself into position on the comet. I know what you’re wondering, “Why do they want to do that?” Let’s explore that in our final section today shall we.
From Hell’s Heart I Stab At Thee!
Once the geography and climatological measurements have been adequately explored and mapped by Rosetta, then the real challenge begins. The smaller lander, Philae, will fire a harpoon at the comet and draw itself onto the surface. From there, small drills will disengage from the feet of the lander and bore into the comet securing it into place. Once Philae is positioned the up close analyses can begin.
That unassuming looking object in the photograph above is the SD2 drill that has been equipped onto Philae. Once the lander has an appropriate landing site and is firmly in place the drill will take over. Capable of boring through material soft as snow or hard as basalt, the drill will take samples of the comet at varying depths, up to 230mm.
Other instruments on the landing craft include an alpha-proton-X-ray spectrometer which will use imaging to better determine composition of “Chury”. Two gas chromatograph/mass spectrometers will determine primordial gaseous elements contained within the comet, two other highly sensitive instruments contribute to the experiment as well that will be used to study isotopic abundances and to identify organic compounds.
Philae is intended to give us insight into the primordial makeup of the comet. Comets are considered the oldest of celestial bodies floating around the heavens and better understanding of these beautiful entities may lead to a better understanding of where we came from. After all, if you subscribe to the theory of evolution than you understand we most likely evolved from single celled organisms. Scientists are hoping for the first time to get a glimpse at single celled organisms growing on a comet.
We’ve had encounters with comets, asteroids, and meteorites before here on Earth. The problem with determining whether or not organisms lived on them or not is that once they collide with the Earth, samples quickly become contaminated by the plethora of life on our little blue ball. By studying the comet in space, scientists will be able to get a clear view of where life may have originally come from, long before our planet even formed.
Unfortunately we’ll have to wait until November to find out what Philae discovers but you can bet I’ll be following this story closely and when more news breaks I’ll be sure to pass it along. Thank you all for reading!
- Ryan Sanders
Thanks for coming along on this journey through space today! As always, share this around on Twitter, Reddit, and Facebook and feel free to follow any of the links below for more information on anything we discussed here today. Happy Learning everyone!
- NASA breakdown of Philae lander
- Philae lander fact sheet (contributing agencies listed here)
- CNN article from Aug. 6th, 2014 on Rosetta mission update
- An interview with Svetlana Gerasimenko
- Livestream videos of ESA and Rosetta mission (highly recommended)
- Guardian report on Rosetta updates
- Huffington Post article on Rosetta updates
- ESA website with plethora of information on Rosetta, Philae, and 67P
- Wiki on 67P/Churyumov-Gerasimenko
