CometWatch is back with two images, to offer a taste of Rosetta’s trajectory in the past couple of weeks.
The first of today’s entries is a 2×2 montage of NAVCAM images obtained on Saturday 28 March from a distance of 31.3 km from the centre of Comet 67P/Churyumov-Gerasimenko. These images were taken as Rosetta departed from the comet, almost seven hours after its close flyby 14 km from the surface of 67P/C-G.
Four image montage of images taken by Rosetta’s NAVCAM from an average distance of 31.3 km from the comet centre. The scale at this distance is 2.7 m/pixel and the size of each 1024 x 1024 pixel frame is 2.7 km. Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
In this view, the small lobe of the comet can be seen in the foreground, with the circular depression in the Hatmehit region well visible in the lower left frame. The large comet lobe is seen in the distance, with portions of the Seth and Ash regions dominating the two right frames.
After the 28 March flyby, Rosetta encountered some navigation issues that that resulted in it moving about 400 km from 67P/C-G. To bring the spacecraft closer to the comet again, a manoeuvre was successfully performed on Wednesday 1 April.
Today’s second CometWatch entry was taken on the following day, Thursday 2 April, at a distance of about 385 from the comet’s centre.
Single-frame image taken by Rosetta’s NAVCAM at about 385 km from the comet centre. The scale at this distance is 33 m/pixel and the size of the image is 34 km. Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
The image is part of a 2×2 raster of four NAVCAM frames. Out of the four images, this one contains most of the comet’s nucleus, while at the same time providing an astonishing view of the comet’s activity, with jets of diffuse material extending diagonally across the frame.
In this orientation, the comet’s small lobe is also in the foreground, with Hatmehit well in sight. Part of the large lobe is visible in the background.
An update on the status of Rosetta and the upcoming planned trajectories will be provided in a separate blog post.
The original frames for both the montage and the single frame image are provided below:
Discussion: 7 comments
Non-linear brightness stretch of the April 2 Navcam image to enhance the jets:
https://i.imgur.com/h7KuwJF.png
Thanks Gerald. I’m wondering if I wouldn’t appreciate these images if I could get a side-by-side of the best views we have from earth of 67P?
In other words, when can we expect some of these jets to be visible on the comet from earth?
John: See the parallel thread on the need for an Earth-based amateur campaign. Not soon from professional telescopes.
Gerald: Some of those things are chunks of material from the comet, are there any stars visible at all in this image? (Just to get a feel for the dust-versus-star question.)
Kamal
Bright spots may be a mix of hot pixels, stars, CR hits, and grains.
Identifying stars is easier with telemetry data.
I didn’t try to identify stars in this image; so I can’t provide a waterproof answer.
Generally I’d say most of the brighter spots are grains; I’m presuming this from consecutive Osiris images, where grains could be tracked from one image to the next.
In van-Allen belts of planets with a sufficiently strong magnetic field, CR (cosmic ray) hits are frequent, but at the location of the comet that’s less likely.
Hot pixels use to be at the same pixel positions for different images, and can be identified that way.
My take on this mosaic:
https://www.flickr.com/photos/105035663@N07/17064032676/in/photostream/
Levels adjusted to show the jets:
https://www.flickr.com/photos/105035663@N07/17090023575/in/photostream/
Hi Claudia and H. NAVCAM Team.
If well most of gas should be going out of fissures, cracks, walls and ‘exhaling’ caves…
On considering [from my memory] the statistical vectors of the jet auras, it’s my best bet that they are generally coming out directly from the dusty plains.
[Excluding from this issue cryo-volcanic gas and ‘ashes’].
That ‘plains’ dust could be the ‘compact’ particulate Alessandra and Marco -from GIADA Team- are commenting about, [among lots of other plausibilities].