Christian Stangl and composer Wolfgang Stangl
From 2014 to 2016, the European Space Agency’s Rosetta spacecraft stayed close to comet 67P/Churyumov-Gerasimenko, collecting scientific data, sending a probe to its surface, and capturing some 400,000 photographs of the comet. Motion designer Christian Stangl and composer Wolfgang Stangl worked together to create the video using many of these images, a complete archive of which you’ll find here.
What I find the most fascinating are the scenes that how dusty the comet is. What look like snow flakes zipping across the landscape are dust particles that were once locked into the comet’s ice but liberated when solar heating vaporized the frozen material. Much of that ice is buried beneath the comet’s surface. As the hot sun bears down on the comet’s crust, it heats the subsurface ice, causing it to vaporize and seek release through cracks and holes in the surface as jets. Those are the geyser-like features you’ll see near the movie’s end.
The jets are especially striking when illuminated from behind, the same way dust kicked up by a car on a dirt road makes it almost impossible to see when you’re driving in the sun’s direction.
At perihelion, when the comet was closest to the sun, astronomers detected lots of surface activity including collapsing overhangs and walls, bouncing boulders and the lifting and redepositing of dust. Each trip around the sun means another round of vaporization and wild activity. Not exactly a safe place to be!
67P has lots of water ice, but it’s three times richer in deuterium than earthly water. Recall that water is composed of two hydrogen atoms and one oxygen atom joined together as H2O. The hydrogen in water is nearly always in its simplest form: a single proton orbited by a single electron. Deuterium is a different form of hydrogen called an isotope that contains an additional neutron (neutral particle) in the nucleus. The extra particle makes deuterium heavier, the reason it’s called heavy water.
In Earth’s oceans there is only one atom of deuterium for every 6,400 atoms of hydrogen. One theory posits that bombarding comets delivered much of the planet’s water billions of years ago, so 67P’s extra deuterium tells us that only certain comets made a contribution, not ones like 67P. Astronomers have found only one or two comets to date that contain water like that the kind that comes from your faucet — 103P/Hartley and 45P/Honda-Mrkos-Pajdusakova.
Both are Jupiter-family comets, so called because Jupiter’s gravitational influence sets their orbits. Jupiter-family comets originated in the Kuiper Belt, a distant region of icy asteroids and comets located beyond Neptune. 67P, Halley’s Comet and others hail from much farther away in the remote Oort Cloud, an enormous spherical collection of billions of comets located between 2,000 and 50,000 times Earth’s distance from the sun.
Current research indicates that comets may have contributed only a modest amount of H2O to the Earth, the majority instead coming from the carbon- and water-rich asteroids residing in the outer zone of the inner asteroid belt located between Mars and Jupiter. Pieces of these asteroids arrive during meteorite falls and are known as carbonaceous chondrites. They once pummeled the Earth in great numbers during the solar system’s youth. Not only are the rocks rich in low-deuterium water like our own but also organic (carbon-containing) compounds that may have seeded the origin of life.