Last updated June 7, 2018 at 2:36 pm
The Rosetta mission was a groundbreaking effort to land on a comet. The images it produced were something else again.
It’s easy to forget that humanity has landed a probe on a comet. The Rosetta spacecraft with its lander Philae, intercepted and landed on the comet 67P/Churyumov-Gerasimenko, an incredible feat which provided groundbreaking direct information on comets.
In 2014 the spacecraft intercepted the comet and established an orbit of between 10-30km from the surface. Two months later, the Philae lander approached and successfully set down on the comet surface. It would subsequently run out of power two days later.
After 2 years of orbiting the comet, Rosetta’s mission finally came to an end, and it was crashed into the surface of the comet.
In that time however, the spacecraft collected vital information about comets including flying through a jet coming from its surface to detect what was being released. Additionally, it captured thousands of photographs using its OSIRIS and NAVCAM camera units, which even now, 2 years on, are mindblowing to look at.
While looking at these photographs we have to keep reminding ourselves that these are of a comet currently hurtling through the solar system – and humanity landed on it. It’s an incredible thing to take in.
The valley between lobes
A mosaic image of Comet 67P/Churyumov-Gerasimenko taken on 15 May 2016 with the navigation camera (NavCam) on board Rosetta. Part of the comet’s small lobe is visible on the right and a portion of the large lobe on the left.
The mosaic is composed of two images taken when Rosetta was about 9.9 km from the comet centre. The image shows a region approximately 1.5 km across.
These images were captured during a series of manoeuvres which saw Rosetta fly to only 5 to 8 km above the surface. During these close passes, ROSINA, the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis, searched for the noble gas xenon, an important tracer of the early Solar System’s composition.
Passing through a plume
A plume of dust bursts from the comet surface, seen by the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) Wide Angle Camera on 3 July 2016. The shadow of the plume is cast across the basin, which is in the Imhotep region.
Not only did Rosetta observe the plume, but its trajectory happened to take it through the plume itself. During this pass Rosetta was able to sample the ejected material with a range on onboard instruments.
The plume lasted for around an hour, and ejected 18kg of dust every second. Initially, the scientists thought that the plume might have been surface ice evaporating in the sunlight. However, Rosetta’s measurements showed there had to be something more energetic going on to fling that amount of dust into space.
It’s still unclear what that energy source is, however it could be pressurised gas bubbles in underground cavities bursting free via ancient vents, or stores of ice reacting violently when exposed to sunlight.
Water Ice in the Imhotep Region
Around 10 hours before the plume (above) occurred, Rosetta captured this image with the OSIRIS Narrow Angle Camera showing the plume site before the outburst.
This view comprises three separate images and combines observations gathered using the system’s red (near-infrared), green, and blue channels (coloured red, orange, and blue respectively to create this false-colour composite). The patches of light blue seen in the frame indicate the presence of water ice.
The outburst was located in the ice-filled depression near the large boulder towards the bottom of the frame.
67P’s craggly surface
Taken by the OSIRIS Narrow Angle Camera on 9 April 2016 during Rosetta’s second mission extension. This incredible image shows the landscape of the comet from an altitude of 62.45km. Captured using using the camera’s filter for the far UV spectrum, for a 10 second exposure.
The main image at the top of the article was captured by the OSIRIS Wide Angle Camera on 22 November 2014, from an altitude of 31 kilometres above the comet’s centre. The exposure time was 0.6480 seconds of visible light.