Tag: Rosetta

Rosetta detects its first dust grains

8:57 am

67P/C-G on August 12, 2014

The Rosetta science team announced today that the spacecraft’s Grain Impact Analyser and Dust Accumulator (GIADA) has captured its first dust grains from Comet 67P/C-G.

Earlier this month, GIADA detected the first four dust grains in its Impact Sensor. The first detection was made on 1 August, when Rosetta was 814 km from 67P/C-G, and about 543 million kilometres from the Sun. Further impacts from three more dust grains were detected on 2, 4, and 5 August, at distances of 603, 286, and 179 km from the comet, respectively.

There is still too little data to come to any firm conclusions about the density and make-up of the coma, but this announcement confirms that the instrument is working as designed. When the comet zips past the Sun at its closest point on August 13, 2015, this instrument will then be able to give us a very good assessment of this particular comet’s behavior as it slowly evaporates.

Meanwhile, the images keep coming. The picture at the top of the post was taken on August 12 from about 64 miles.

Leave a comment

Another Rosetta closeup of 67P/C-G

4:15 pm

67P on August 8

The above image is not the most recent daily image from Rosetta, but it is the most interesting of the last three.

It shows the side of the comet nucleus that has not been featured in most images, as the topographical differences between its two sections is not as distinctly highlighted. What is highlighted is the neck that connects the two sections, lighter colored and thus likely made up of less dusty ice.

Also of interest here is the circular features on the larger bottom section. These certainly resemble craters, and are likely remnants of early impacts that are now been corroded away as the nucleus’s ice particles evaporate off the surface. The scientific question here is this: Why are crater features more evident on this side and section of the comet nucleus than on other areas of its surface?

Leave a comment

67P from 52 miles

9:32 am

67P from 52 miles, August 7, 2014

The image above was taken on August 7 from only 52 miles. For the first time I had to scale it down slightly so that it would fit on the webpage.

My impression with this image is that there actually might be hints of some very ancient craters at several of the vaguely circular pitted features. For example, look at the large feature on the end of the nucleus’s smaller component on the right. This might be a crater that now is significantly eroded as the comet’s surface evaporated away each time it approached the Sun every 6.5 years.

Leave a comment

Comet 67P on the day of rendezvous

8:39 am

67P/C-G on August 6

The image above was taken at a distance of 60 miles by Rosetta’s navigation camera on August 6, the day the spacecraft rendezvoused and began flying in tandem with it. It looks at the “backside” of the comet, the side where the distinction between its two components is less pronounced. Once again, no obvious craters, and the surface is pockmarked and corroded.

One comment

Rosetta arrives

10:14 am

Rosetta has successfully achieved orbit around Comet 67P/C-G and has transmitted its first close up images. More information here and here about the rendezvous and what science the mission scientists plan to do as they orbit the comet.

The image below is looking down and past the comet’s smaller component as it casts a shadow on the neck and the larger component beyond. As with the earlier images, the comet’s pitted and corroded surface, lacking any obvious craters, is reminiscent to me of a pile of dirty snow that has been dissolving away. In fact, when I lived in New York I would see this kind of look every winter. When the city would get a big snowfall snowplows would push it into large mounds on the side of the road. As time passed these piles would get dirty from the city’s soot and grime, and also slowly melt away. After several weeks it would look almost exactly like the surface of Comet 67P/C-G.

The images and data that will come down from Rosetta over the next year and half as it orbits the comet in its journey around the Sun will be most fascinating. Stay tuned!

67P/C-G up close

12 comments

Comet 67P/C-G at 126 miles

8:57 am

Comet 67P/C-G at 126 miles

The image above was taken by Rosetta on August 4 from only 126 miles (234 kilometers). Unlike earlier images, this image is raw, uncropped and unprocessed. All I have done is rescale it to fit on my webpage. As they explain at the link,

As you can see, the comet is not centred in the full-frame image. This is a result of the rendezvous burn conducted the previous day, which adjusted Rosetta’s trajectory towards the comet. This effect is corrected for in the commands sent to the spacecraft after the new orbit has been determined.

The science team also notes that beginning tomorrow, the comet will be close enough that they will no longer have to provide a cropped close-up using the navigation camera and that this uncropped raw version will be sufficient.

Rendezvous and orbital insertion on Wednesday!

Leave a comment

67P from less than 200 miles

9:15 am

67P on August 3

Today’s Rosetta image of Comet 67P, shown above, gives us a different angle of the comet. The spacecraft was only 186 miles (300 kilometers) away when it snapped the picture, and this side view emphasizes the nucleus’s jagged shape.

I am reminded of what happens to a block of ice when you spray warm water on it. It begins to melt away, but very randomly and unevenly, producing very weird shapes and the surface evaporates off. In the case of Comet 67P, the nucleus is a dirty ball of ice, and the Sun’s rays have been causing its surface to evaporate off every time it approaches the Sun. Thus, we get a very weird shape.

Leave a comment

Today’s Comet 67P image

9:05 am

Comet 67P on August 2

The image above was taken on August 2 using Rosetta’s navigation camera. It has been processed by the science team to bring out the details. I have also rotated it to match the August 1 image taken at a distance of 620 miles that was taken by Rosetta’s OSIRIS narrow angle camera, designed to do the actual science.

You can see that the navigation camera does a pretty good job on its own of capturing the comet’s nucleus. Both images show that the instruments are working perfectly, and thus tell us that the next few months will be quite spectacular after Rosetta goes into orbit in three days, followed in November by the landing of Philae somewhere on the comet’s surface.

If you download both images and then switch back and forth between them you can get a better feel for the geometry of the surface features.

Leave a comment

Comet 67P from 1000 k

11:06 pm

67P from 1000 kilometers

Above is a new image of Comet 67P as seen from about 1000 kilometers, or about 620 miles, released by the Rosetta science team today. The image was taken on August 1 and has been processed somewhat to bring out the details. The black spot near the junction between the nucleus’s two sections is not real but an artifact of the camera’s CCD.

This image is the first real clear and sharp look at the nucleus, and what it shows us is a surface quite different from the many other asteroids that science probes have imaged close-up in the past. From this angle there are far few craters visible then is normally seen on asteroids, and the surface has complex roughness and pitted look that I suspect the planetary geologists are right now scratching their heads about and waving their arms trying to explain. My first guess, which no one should take too seriously, is that as material vents off the comet when it gets close to the Sun it leaves behind these scars.

One more thing: If you go here you can see a number of additional image releases in the last 24 hours, all fascinating. This link explains that the features that looked like craters in earlier images were actually artifacts from the camera’s CCD.

Leave a comment

Getting closer

8:29 am

Comet 67P on July 31

This image of Comet 67P from Rosetta was taken yesterday. Though it has not been processed like the image I posted yesterday, more details continue to come out as the spacecraft each day gets closer to the comet. This image was taken from a distance of 825 miles, 375 miles closer than the previous day.

Very soon these close-up images will become too large to show the entire nucleus in one image. Rosetta will instead begin to snap images of specific features.

Meanwhile, the Rosetta science team released its first temperature readings of the comet.
» Read more

Leave a comment

New Rosetta comet images

6:34 pm

New images from Rosetta have a resolution of 100 meters per pixel and are finding that the neck connecting the comet’s two sections is apparently much brighter than the rest of the nucleus.

As earlier images had already shown, 67P may consist of two parts: a smaller head connected to a larger body. The connecting region, the neck, is proving to be especially intriguing. “The only thing we know for sure at this point is that this neck region appears brighter compared to the head and body of the nucleus”, says OSIRIS Principal Investigator Holger Sierks from the Max-Planck-Institute for Solar System Research (MPS) in Germany. This collar-like appearance could be caused by differences in material or grain size or could be a topographical effect.

It looks like this comet is going to turn out to be one of the most fascinating objects any space probe has visited in a long time.

Leave a comment

More images from Rosetta

5:24 pm

67P

The comet that Rosetta will orbit is getting stranger and stranger, with new images suggesting that it is really two objects stuck together.

The pictures show that 67P/Churyumov-Gerasimenko appears to be not one but two objects joined together. It is what scientists call a “contact binary”. How the comet came to take this form is unknown. It is possible that 67P suffered a major fracture at some point in its past; it is also possible the two parts have totally different origins.

What is clear is that the European Space Agency (Esa) mission team now has additional and unexpected considerations as it plans how to land on the comet later this year – not least, which part of the comet should be chosen for contact?

One comment

Rosetta snaps more comet pictures

9:23 am

rotating comet nucleus

Rosetta’s new images of Comet 67P/Churyumov-Gerasimenko show the very irregular shape and rotation of its nucleus.

These images were taken on July 4 from a distance of only 23,000 miles. The rendezvous is expected in early August, with the touchdown of Rosetta’s landing probe Philae sometime in November after they have done a reconnaissance of the nucleus to pick a landing spot.

Leave a comment

Rosetta measures its comet

11:09 am

As Rosetta approaches Comet 67P/Churyumov-Gerisimenko, it has measured the amount of water evaporating of the comet as it slowly comes to life as it approaches the Sun.

ESA’s Rosetta spacecraft has found that comet 67P/Churyumov–Gerasimenko is releasing the equivalent of two small glasses of water into space every second, even at a cold 583 million kilometres from the Sun. The first observations of water vapour streaming from the comet were made by the Microwave Instrument for Rosetta Orbiter, or MIRO, on 6 June, when the spacecraft was about 350 000 kilometres from the comet. Since the initial detection, water vapour has been found every time MIRO has been pointed towards the comet.

That rate of evaporation will increase with time.

Leave a comment

Rosetta’s comet has unexpectedly gone to sleep.

10:04 am

Rosetta’s comet has unexpectedly gone to sleep.

An image snapped earlier this month by ESA’s Rosetta spacecraft shows its target comet has quietened, demonstrating the unpredictable nature of these enigmatic objects. The picture was captured on 4 June by Rosetta’s scientific camera, and is the most recent full-resolution image from the narrow-angle sensor. It has been used to help fine-tune Rosetta’s navigation towards comet 67P/Churyumov–Gerasimenko, which was 430 000 km away at the time.

Strikingly, there is no longer any sign of the extended dust cloud that was seen developing around nucleus at the end of April and into May, as shown in our last image release. Indeed, monitoring of the comet has shown a significant drop in its brightness since then.

Rosetta’s approach for the next few months and arrival at the comet in August should be quite exciting.

Leave a comment

Rosetta photographs its target comet as it comes to life.

6:25 am

Rosetta photographs its target comet as it comes to life.

The comet 67P/Churyumov-Gerasimenko, target of ESA’s Rosetta mission, has begun to develop a dust coma. This can be seen in a series of images taken by OSIRIS, the spacecraft’s scientific imaging system, between March 27th and May 4th. In the images from the end of April, the dust that the comet is already emitting is clearly visible as an evolving coma and reaches approximately 1300 kilometers into space.

Leave a comment

The German-built comet lander Philae has been successfully reactivated on Rosetta.

9:24 am

The German-built comet lander Philae has been successfully reactivated on Rosetta.

Philae will be ejected from the Rosetta mothership in November to latch itself onto the comet’s icy surface with harpoons and screws. The lander has its own suite of science instrumentation to take the first-ever photos and measurements from a comet’s surface. Engineers plan a four-week commissioning phase for Philae to check on its health and activate the lander’s 10 instruments.

Leave a comment

The comet that the European probe Rosetta will visit in August has awakened.

11:37 am

The comet that the European probe Rosetta will visit in August has awakened.

Already 67P/Churyumov-Gerasimenko is approximately 50 percent brighter than in the last images from October 2013. While the comet has moved another 50 million kilometers closer to Earth in this time (and 80 million kilometers closer to the Sun), the increase in brightness cannot be explained by the smaller distance alone. “The new image suggests that 67P is beginning to emit gas and dust at a relatively large distance from the Sun”, says Colin Snodgrass from the MPS. This confirms a study presented by Snodgrass and his colleagues last year in which they had compared the comet’s brightness as recorded during its previous orbits around the Sun. The calculations showed that already in March 2014 its activity would be measurable from Earth.

Update: A preprint paper published today on the astro-ph website predicts that Rosetta will see an unusual topographical feature on the comet’s surface when it arrives in August:

Comet 67P/Churyumov-Gerasimenko. The Secular Light Curve (SLC) of this comet exhibits a photometric anomaly in magnitude that is present in 1982, 1996, 2002 and 2009. Thus it must be real. We interpret this anomaly as a topographic feature on the surface of the nucleus that may be a field of debris, a region made only of dust or an area of solid stones but in any case it is depleted in volatiles. We predict that images taken by spacecraft Rosseta will show a region morphologically different to the rest of the nucleus, at the pole pointing to the Sun near perihelion.

4 comments

Because of a computer reboot, Rosetta’s revival from hibernation came 18 minutes late.

3:57 pm

Because of a computer reboot, Rosetta’s revival from hibernation came 18 minutes late.

[Rosetta] woke yesterday as planned, to the relief of ESA scientists – but the signal it sent home to confirm it was awake reached Earth late, fraying the nerves of some mission controllers in the meantime. Due to call at 1745 GMT, Rosetta did not announce its revival until 1818. Fifteen minutes could be explained because the spacecraft’s computer checked the on-board clock only every quarter of an hour. The additional 18 minutes, however, was a mystery.

Now, the telemetry has shown that soon after Rosetta’s first revival sequence had started, the on-board computer automatically rebooted and the sequence started again, causing 18 minutes of delay.

It seems all is well now, though the engineers plan to spend some time pinpointing the cause of the reboot.

One comment

After three years in hibernation Europe’s Rosetta comet probe has successfully come back to life.

4:10 pm

After three years in hibernation Europe’s Rosetta comet probe has successfully come back to life.

The craft at the heart of ESA’s €1-billion (US$1.4-billion) comet-hunting mission was shut down in 2011 to save energy while travelling in deep space. Rosetta successfully re-established communications with Earth on 20 January.
With an alarm pre-set for 10:00 GMT, a signal was expected at any time from 17:30 GMT, once the spacecraft had warmed up and turned its antenna towards Earth. But Rosetta kept everyone guessing, with the first sign that everything had gone to plan only arriving around 40 minutes later.

ESA’s European Space Operations Centre erupted in cheering and hugging as small spikes appeared in radio signals received at NASA deep-space communications centres in Canberra and in Goldstone, California.

Leave a comment
1 … 4 5 6 7