Goodbye, Rosetta

rosetta-from-10kmThe Rosetta spacecraft “landed” on Comet 67P/Churyumov-Gerasimenko at 11:19 UTC yesterday. The picture above was taken from a range of about 16 km during the descent. It shows objects about 30 cm across. The image below is the last image sent from the spacecraft at an estimated altitude of 20 m. The area shown is about 2.4 m across. The resolution is roughly 5 mm. Contact was lost with the spacecraft when it contacted the surface of the comet, causing its antenna to point away from the Earth.rosetta-last-image

Image Credits: ESA

Philae’s Multiple Landings

Data from both the Philae lander and Rosetta orbiter experiments have been used along with simulations based on Philae’s mechanical design to reconstruct the lander’s attitude and motion during its descent and multiple touchdowns on Comet 67P/Churyumov-Gerasimenko on 12 November, 2014.


Video Credit: ESA

67P/Churyumov-Gerasimenko at Perihelion

Rosetta_approaching_perihelionThese picture of Comet 67P/Churyumov–Gerasimenko were taken by Rosetta’s OSIRIS narrow-angle camera on 12 August, 2015, just a few hours before the comet reached perihelion, the closest point to the Sun along its 6.5-year orbit,

The image at left was taken at 14:07 GMT, the middle one at 17:35 GMT, and the final image at 23:31 GMT. The spacecraft was about 330 km from the comet. The comet’s activity (at its peak intensity for the next few weeks) is clearly visible; a significant outburst can be seen in the image captured at 17:35.

Image Credit: ESA

Comet Cliffs

cometcliffs_rosetta_960These high cliffs occur on the surface of a comet. They were discovered to be part of the dark nucleus of Comet Churyumov–Gerasimenko by Rosetta, the ESA spacecraft orbiting the comet since early August. These ragged cliffs were imaged by the spacecraft about two weeks ago. Although towering about one kilometer high, the low surface gravity of Comet CG would likely make a jump from the cliffs survivable. At the foot of the cliffs is relatively smooth terrain dotted with boulders as large as 20 meters across.

Image Credit: ESA

A Comet in Color …

ESA_Rosetta_OSIRIS_Color… but not a very much color. Rosetta’s OSIRIS team have produced a color image of Comet 67P/Churyumov-Gerasimenko as it would be seen by the human eye. The comet turns out to be very grey indeed, with only subtle color variations across its surface.

This picture was assembled from three images taken with the Narrow Angle Camera (NAC) of the scientific imaging system OSIRIS in red (744 nm wavelength), green (536 nm), and blue (481 nm) filters on 6 August 2014, from a distance of 120 kilometres. The image area is roughly 4 km square.

Image Credit: ESA

Following the Bouncing Lander

OSIRIS_spots_PhilaeThis mosaic was assembled from a series of images captured by Rosetta’s OSIRIS camera taken over the half-hour spanning the first touchdown of the Philae lander Comet 67P/CG. The time of each of image is marked on the corresponding insets and is in UTC. A comparison of the touchdown area shortly before and after first contact with the surface is shown at the top.

The images were taken with the OSIRIS narrow-angle camera when the spacecraft was 17.5 km from the comet centre, or roughly 15.5 km from the surface. The enlarged insets cover a 17 x 17 m area.

From left to right, the images show Philae descending towards and across the comet before touchdown. The image taken after touchdown, at 15:43 GMT, confirms that the lander was moving east at a speed of about 0.5 m/s as it bounced across the surface of the comet.

Philae‘s actual final landing spot still hasn’t been found. After touching down and bouncing again at 17:25 UTC, it finally landed at 17:32. The mission imaging team believes that by combining the CONSERT ranging data with OSIRIS and navcam images from the orbiter and images from near the surface with data from Philae’s ROLIS and CIVA cameras they will be able to determine the lander’s whereabouts.

Image Credit: ESA

On the Surface of a Comet

Welcome_to_a_cometThe Rosetta mission lander is “safely” on the surface of its comet. One of Philae‘s feet can be seen at the bottom left of this picture of the surface of C67/P Churyumov-Gerasimenko. Philae bounced twice before settling and returning images from the surface, traveling a kilometer or so after ricocheting off of its desired target. A surface panorama suggests that the lander has come to rest tilted and near a shadowing wall. The lander’s solar panels are getting less illumination than if it had landed in the open. The science instruments are working as planned and data is being relayed when the main Rosetta spacecraft is above the lander’s new horizon. However, with good recharging from the solar array, the batteries will not last as long as had been hoped.

Image Credit: ESA

67P/Churyumov-Gerasimenko: A Bit Closer

Rosetta 20141028
This four-image montage was taken by Rosetta‘s navigation camera from a distance of 9.7 km from the center of comet 67P/C-G (about 7.7 km from the surface). The original image scale is about 65 cm/pixel, so each 1024 x 1024 pixel frame scales about 665 m across. The resolution is reduced to about 2.3 m/pixel in this picture.

Image Credit: ESA

Rosetta’s Comet Stinks

ESA reports that Comet 67P/Churyumov-Gerasimenko stinks. Analysis of data sent back by Rosetta shows that the comet is made up of water, carbon dioxide, and carbon monoxide. It also contains ammonia (NH3), methane (CH4), methanol (CH3OH), formaldehyde (CH2O), hydrogen sulphide (H2S), hydrogen cyanide (HCN), sulphur dioxide (SO2), and carbon disulphide (CS2).

The perfume of 67P/C-G is quite strong, with the odour of rotten eggs (hydrogen sulphide), horse stable (ammonia), and the pungent, suffocating odour of formaldehyde. This is mixed with the faint, bitter, almond-like aroma of hydrogen cyanide. Add some whiff of alcohol (methanol) to this mixture, paired with the vinegar-like aroma of sulphur dioxide and a hint of the sweet aromatic scent of carbon disulphide, and you arrive at the ‘perfume’ of our comet.