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The ESA’s mission to comet 67P/Churyumov-Gerasimenko has been one of the most exciting space missions in recent memory. Yes, the Philae lander had a bit of a rough landing – but it managed to conduct some science before powering down.
While the excitement has died down a bit from November’s drama-filled Philae landing – the Rosetta probe has kept busy.
Everything from exact measurements of the comet to even wind has been revealed in these new studies. I’ll break down some of the more interesting aspects below.
First up? Measurements. As most of you know, comet 67P’s appearance is a bit unique. It has two lobes. The smaller one measures in at 2.6 x 2.3 x 1.8 km. The larger one measures 4.1 x 3.3 x 1.8 km. The Radio Science instrument onboard Rosetta measured the comet’s mass at 10 billion tonnes. I wouldn’t want to see this bad boy in our skies.
Scientists on the Rosetta team believe the comet has a very high porosity (how much of the comet is open space) of 70-80%. The insides of the comet is likely made up of weakly bonded ice/dust clumps mixed with empty spaces between them.
Nearly 70% of the comet’s surface has been imaged by the Rosetta probe. A few parts of the comet remain hidden in shadow, most notably in the southern hemisphere.
5 distinct types of terrain have been spotted. Well, as distinct as you can get with a comet made up primarily of rock/dust/ice: dust-covered; brittle materials with pits and circular structures; large-scale depressions; smooth terrains; and exposed more consolidated (‘rock-like’) surfaces.
19 regions with clearly-defined boundaries have been cataloged so far. Rosetta scientists are keeping with the Egyptian theme for the mission and named them after deities. Check them out in the image below.
One of the coolest discoveries is ‘wind’ on the comet’s surface. Dune-like ripples can be seen on the surface. Escaping gases blow across the surface causing the ripples. Since there’s barely any gravity on the comet, it doesn’t take much for blowing gas to form ripples.
The comet’s coma has surprised scientists. It isn’t uniform. Instead, they are observing significant changes in the composition of the coma. Right now, scientists are seeing a dust-to-gas ratio of around 4 to 1. That is expected to shift towards gas as the comet gets closer to the sun and ice grains melt off versus dust grains.
“Rosetta is essentially living with the comet as it moves towards the Sun along its orbit, learning how its behaviour changes on a daily basis and, over longer timescales, how its activity increases, how its surface may evolve, and how it interacts with the solar wind,” says Matt Taylor, ESA’s Rosetta project scientist.