A 3-D image from the Rosetta spacecraft showing Comet 67P/Churyumov-Gerasimenko and its boulder-strewn 'neck' region. Also visible is an exposed cliff face and numerous crater-like depressions. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
You always have a pair of those cardboard red-blue 3-D glasses by your desk, right? Well, grab them and take a look at this view of Comet 67P/Churyumov-Gerasimenko, just out from the Rosetta mission team. It almost feels like you’re right there with the spacecraft.
Notice the cliffs (see the exposed layers there?), boulders and depressions. The 3-D image was created using two images (you can see the two images here at the ESA blog) They were both taken on 7 August 2014, from a distance of 104 kilometres through the orange filter of the OSIRIS narrow-angle camera. ESA says the two images are separated by 17 minutes and the exposure time is 138 milliseconds.
A view of the nucleus of Comet 67P/Churyumov–Gerasimenko taken by the Rosetta spacecraft Aug. 11, 2014. Credit: ESA/Rosetta/NAVCAM
Mark your calendars, astronomy geeks: exactly one year from today, the comet the Rosetta spacecraft is chasing will make its closest approach to the Sun. As Comet 67P/Churyumov–Gerasimenko draws closer to the star, the radiation pressure will cause gas, ice and dust to stream off the comet in ever greater quantities, scientists expect.
But that process is already starting. Preliminary measurements by a dust detector aboard the Rosetta spacecraft show that dust is at least as frequent — or perhaps even more abundant — than what models have predicted. Meanwhile, as reported on Universe Today earlier this week, Rosetta’s COSIMA instrument is also doing dust measurements.
Rosetta’s Grain Impact Analyser and Dust Accumulator (GIADA) has already detected four dust grains on its impact sensor. The detections took place between Aug. 1 and Aug. 5 at various distances as Rosetta approached the comet, starting from as far as 814 kilometers (506 miles) to as close as 179 kilometers (111 miles). Rosetta arrived at the comet on Aug. 6.
The first impact was just a tad higher than the detection limit for GIADA, scientists said. They also estimated how big the grains are based on how quickly they crash into the impact detector — anywhere from tens of microns (the width of a human hair) to a few hundreds of microns across.
While the results are scientifically interesting, the European Space Agency pointed out that they will also have practical use.
An artist’s impression of the Grain Impact Analyser and Dust Accumulator (GIADA) on the Rosetta spacecraft, which is collecting dust from Comet 67P/Churyumov–Gerasimenko. The inset is a an analog dust grain used in the laboratory to calibrate the instrument. Credit: ESA/Rosetta/GIADA/Univ Parthenope NA/INAF-OAC/IAA/INAF-IAPS
A lander called Philae is expected to touch down on the comet in November, so dust predictions will help planning for that. And for Rosetta itself, knowing the dust environment can help protect the spacecraft from strikes.
“GIADA will also provide inputs to other instruments on-board Rosetta, and will help improve coma dust models in support of the Philae landing operations,” ESA stated.
“Furthermore, GIADA will play an important role for the health and the safety of Rosetta and its instruments, providing information about the deposition rates of dust on optical components and critical parts of the spacecraft, such as the solar panels.”
ESA added that the grains themselves are likely a mixture of silicates, organics and some other stuff. Ice from the nucleus surrounds the grains, and the ice itself becomes a gas when the Sun warms the comet. Dust surrounds the comet in a coma and as it gets closer to the Sun, it streams out as a tail.
A picture of Comet 67P/Churyumov-Gerasimenko. Credit: ESA/Rosetta/NAVCAM
What’s one of the first things you do when arriving at a new destination? Likely it would be scoping out the local neighborhood. Getting a sense of its terrain and the good things to do around there.
That’s part of what Rosetta’s team is working on since arriving at its comet early in the morning of Aug. 6 (Eastern time). While only a few pictures have been beamed back to the public so far of Comet 67P/Churyumov-Gerasimenko, the glimpses of its surface are tantalizing. Which is important, because a little spacecraft is on its way there.
As the team busily calibrates its instruments and snaps pictures of the surface, one of their first tasks will be to pick a landing site for Philae, the machine that is scheduled to leave Rosetta and actually touch softly down on the surface in November. This is the first time such a soft-landing has been attempted, and it’s been a long decade of waiting for the scientists who sent the two spacecraft on their way.
Picking a spot will be difficult for the team, they explained last week. The gravity is light and the terrain is not only difficult to navigate, but also hard to choose from. Would you prefer a crater or a cliff? That will be what science investigators will examine in the coming months.
As they do that, check out the latest pictures of the comet in the gallery below.
A view of Comet 67P/Churyumov-Gerasimenko taken by the Rosetta spacecraft on Aug. 9, 2014. Credit: ESA/Rosetta/NAVCAMA dark hollow beckons in this picture of Comet 67P/Churyumov-Gerasimenko taken by the Rosetta spacecraft Aug. 5, 2014. Credit: ESA/Rosetta/NAVCAMThe Rosetta spacecraft captured the “rubbe duckie” shape of Comet 67P/Churyumov-Gerasimenko on Aug. 6, 2014. Credit: ESA/Rosetta/NAVCAMThe mottled surface of Comet 67P/Churyumov-Gerasimenko beckons in this picure taken by the Rosetta spacecraft on Aug. 7, 2014. Credit: ESA/Rosetta/NAVCAM
Comet 67P/Churyumov-Gerasimenko imaged by OSIRIS on July 29, 2014
WOW! We’re really getting to the good stuff now! This is no computer-generated shape model, this is the real deal: the double-lobed nucleus of Comet 67P/C-G, as imaged by Rosetta’s OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) narrow-angle camera on Tuesday, July 29. At the time just about a week away from making its arrival, ESA’s spacecraft was 1,950 km (1,211 miles) from the comet when this image was taken. (That’s about the distance between Providence, Rhode Island and Miami, Florida… that’s one fancy zoom lens, Rosetta!)
Comet 67P/Churyumov-Gerasimenko imaged on July 14, 2014 by OSIRIS from a distance of approximately 12,000 km. (ESA)
This latest image reveals some actual surface features of the 4-km-wide comet, from a few troughs and mounds to the previously-noted bright band around the “neck” connecting the two lobes. The resolution in the July 29 OSIRIS image is 37 meters per pixel.
Since Rosetta is quickly closing the gap between itself and the comet we can only expect better images to come in the days ahead, so stay tuned — this is going to be an exciting August!
Keep up with the latest news on ESA’s Rosetta blog here, and find out where exactly Rosetta and Comet 67P/C-G are in the Solar System here.
Comet 67P/C-G photographed on July 14, 2014 from a distance of approximately 12 000 km.
Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
I thought the photos earlier this week were amazing. This little movie, made of 36 ‘smoothed’ or interpolated images of Comet 67P/Churyumov-Gerasimenko, takes it to the next level, showing the comet’s complex shape even more clearly as Rosetta nudges ever closer to its target. Some have likened it to a duck, a boot and even a baby’s foot. The original photos used for the animation were more pixelated, but a technique known as “sub-sampling by interpolation” was used to smooth out the pixels for a more natural look. Be aware that because of processing, 67P C-G appears smoother than it might be. While the surface looks textured, including what appears to be a small crater atop the duck’s head, we have to be careful at this stage not to over-interpret – some of the details are artifacts.
Raw pixelated image of the comet (left) and after smoothing. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
No one knows yet how such an unusual shape formed in the first place. Possibly the comet is a ‘contact binary’ made of two separate comets or two parts of larger, shattered comet that stuck together during a low-velocity collision. This may have happened more 4 billion years ago when the icy building blocks of the planets and comets were numerous and collisions far more frequent than they are today. Contact binaries aren’t uncommon; we see them in asteroids and comets alike.
* The comet may have once been a more spherical object but after many trips around the sun developed an asymmetrical shape from ice vaporization and outgassing.
* A near-catastrophic impact blasted away a huge chunk of comet ice.
* The strong gravitational pull experienced during a close pass of a large planet like Jupiter or Saturn may have pulled it into an irregular shape.
* A large outburst could have weakened a region on the comet’s surface that later crumbled away.
Detailed view of the likely contact binary asteroid 25143 Itokawa visited by the Japanese spacecraft Hayabusa in 2005. Credit: JAXA
“We will need to perform detailed analyses and modelling of the shape of the comet to determine how best we can fly around such a uniquely shaped body, taking into account flight control and astrodynamics, the science requirements of the mission, and the landing-related elements like landing site analysis and lander-to-orbiter visibility,” said Rosetta Mission Manager Fred Jansen. ” But with fewer than 10,000 km to go before the August 6th rendezvous, our open questions will soon be answered.”
In the meantime, keep the photos and movies coming. We can’t get enough.
Diagram of Comet 67P/C-G compared to terrestrial landmarks (ESA)
Pretty darn big, I’d say.
The illustration above shows the relative scale of the comet that ESA’s Rosetta and Philae spacecraft will explore “up-close and personal” later this year. And while it’s one thing to say that the nucleus of Comet 67P/Churyumov-Gerasimenko is about three by five kilometers in diameter, it’s quite another to see it in context with more familiar objects. Think about it — a comet as tall as Mt Fuji!
Artist’s impression (not to scale) of the Rosetta orbiter deploying the Philae lander to comet 67P/Churyumov–Gerasimenko. Credit: ESA–C. Carreau/ATG medialab.
At the time of this writing Rosetta is 35 days out on approach to Comet 67P/C-G, at a distance of about 51,000 km (31,700 miles) and closing. Three “big burn” maneuvers have already been performed between May 7 and June 4 to adjust the spacecraft’s course toward the incoming comet, and after smaller ones on June 18 and July 2 there are a total of five more to go. See details of Rosetta’s burn maneuvers here.
Luckily the remaining burns are relatively small compared to the first three, with the final being very brief, so any data contamination by Rosetta’s own exhaust shouldn’t become an issue once the spacecraft has established orbit in August.
Launched in March 2004, ESA’s Rosetta mission will be the first to orbit and land a probe on a comet, observing its composition and behavior as it makes its close approach to the Sun in 2015. Click here to see where Rosetta is right now.
Note: While 3-5 km seems pretty big (especially when stood on end) comet nuclei can be much larger, 10 to 20 km in diameter up to the enormous 40+ km size of Hale-Bopp. As comets go, 67P/C-G is fairly average. (Except that, come August, it will be the only comet with an Earthly spacecraft in tow!)
Artist's conception of Rosetta's target, 67P/Churyumov–Gerasimenko, which is losing two 5-ounce (150 millileter cups) of water every second while still 362 million miles (583 million kilometers) from the sun. The water vapor output will increase as the comet gets closer; these measurements were made on June 6, 2014. Credit: ESA
Feeling thirsty? If you could somehow capture the water vapor from Rosetta’s comet, you would have the equivalent of two water glasses every second. That’s more than scientists expected given that Comet 67P/Churyumov–Gerasimenko is still screaming into the inner solar system at more than double the distance from Mars to the Sun.
“We always knew we would see water vapor outgassing from the comet, but we were surprised at how early we detected it,” stated Sam Gulkis, the instrument’s principal investigator at NASA’s Jet Propulsion Laboratory in California.
“At this rate, the comet would fill an Olympic-size swimming pool in about 100 days. But, as it gets closer to the Sun, the gas production rate will increase significantly. With Rosetta, we have an amazing vantage point to observe these changes up close and learn more about exactly why they happen.”
Comets are sometimes called “dirty snowballs” because they are collection of debris and ices. From their origin points in the outer solar system, occasionally one will be pushed towards the Sun.
Artist’s impression (not to scale) of the Rosetta orbiter deploying the Philae lander to comet 67P/Churyumov–Gerasimenko. Credit: ESA–C. Carreau/ATG medialab.
As it gets closer, the ices bleed off and the comet develops an envelope of gases that eventually, with the Sun’s help, will turn into a tail. Some of the major “volatiles” include water, carbon monoxide, methanol and ammonia.
The observations were made on June 6 by an instrument called the Microwave Instrument for Rosetta Orbiter (MIRO), taken when the spacecraft was about 218,000 miles (350,000 km) away from its target. MIRO is trying to figure out the relative ratios of the ingredients of the coma, and will keep following along with the comet as it makes its closest approach to the sun in August 2015.
Rosetta, meanwhile, will get up close to Comet 67P/Churyumov–Gerasimenko by August and if all goes well, subsequently deploy a lander called Philae to check out the surface of the comet.
Artist's impression (from 2002) of Rosetta orbiting Comet 67P/Churyumov-Gerasimenko. Credit: ESA, image by AOES Medialab
It’s no surprise that there is a lot of water in comets. The “dirty snowballs” (or dusty ice-balls, more accurately) are literally filled with the stuff, so much in fact it’s thought that comets played a major role in delivering water to Earth. But every comet is unique, and the more we learn about them the more we can understand the current state of our Solar System and piece together the history of our planet.
ESA’s Rosetta spacecraft is now entering the home stretch for its rendezvous with comet 67P/Churyumov-Gerasimenko in August. While it has already visually imaged the comet on a couple of occasions since waking from its hibernation, its instruments have now successfully identified water on 67P for the first time, from a distance of 360,000 km — about the distance between Earth and the Moon.
The detection comes via Rosetta’s Microwave Instrument for Rosetta Orbiter, or MIRO, instrument. The results were distributed this past weekend to users of the IAU’s Central Bureau of Astronomical Telegrams:
S. Gulkis, Jet Propulsion Laboratory, California Institute of Technology, on behalf of the Microwave Instrument on Rosetta Orbiter (MIRO) science team, reports that the (1_10)-(1_01) water line at 556.9 GHz was first detected in Comet 67P/Churyumov-Gerasimenko with the MIRO instrument aboard the Rosetta spacecraft on June 6.55, 2014 UT. The line area is 0.39 +/-0.06 K km/s with the line amplitude of 0.48 +/-0.06 K and the line width of 0.76 +/-0.12 km/s. At the time of the observations, the spacecraft to comet distance was ~360,000 km and the heliocentric distance of the comet was 3.93 AU. An initial estimate of the water production rate based on the measurements is that it lies between 0.5 x 10^25 molecules/s and 4 x 10^25 molecules/s.
Although recent images of 67P/C-G seem to show that the comet’s brightness has decreased over the past couple of months, it is still on its way toward the Sun and with that will come more warming and undoubtedly much more activity. These recent measurements by MIRO show that the comet’s water production rate is “within the range of models being used” by scientists to anticipate its behavior.
Rosetta image of Comet 67P/C-G on June 4, 2014, from a distance of 430,000 km. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
This August Rosetta will become the first spacecraft to establish orbit around a comet and, in November, deploy its Philae lander onto its surface. Together these robotic explorers will observe first-hand the changes in the comet as it makes its closest approach to the Sun in August 2015. It’s going to be a very exciting year ahead, so stay tuned for more!
Artist's impression (from 2002) of the Philae lander on Comet 67P/Churyumov-Gerasimenko. Credit: ESA / AOES Medialab
Comets are notoriously hard to predict — just ask those people on Comet ISON watch late in 2013. So as Rosetta approaches its cometary target, no one really knows what the comet will look like from up close. Yes, there are pictures of other cometary nuclei (most famously, Halley’s Comet) but this one could look completely different.
Several artists have taken a stab at imagining what Rosetta will see when it gets close to the comet in August, and what Philae will touch on when it reaches the surface in November. You can see their work throughout this article.
Meanwhile, the European Space Agency just issued an update on what they can see of 67P/Churyumov–Gerasimenko from half a million km away — the comet is quieter, they said.
“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,” ESA stated in a press release. “Indeed, monitoring of the comet has shown a significant drop in its brightness since then.”
Artist’s impression (from 2002) of Rosetta orbiting Comet 67P/Churyumov-Gerasimenko. Credit: ESA, image by AOES Medialab
This variability is common in comets, but it’s the first time it’s been seen from so close, ESA said. Comets warm up as they approach the sun, releasing ice, gas and dust that form a swarm of material.
“As comets are non-spherical and lumpy, this process is often unpredictable, with activity waxing and waning as they warm. The observations made over the six weeks from the end of April to early June show just how quickly the conditions at a comet can change,” ESA added.
Rosetta flies above the Philae lander on Comet 67P/Churyumov-Gerasimenko in this artist’s impression from 2002. Credit: Astrium – E. ViktorArtist’s impression (from 2002) of the Philae lander during descent on Comet 67P/Churyumov-Gerasimenko. Credit: ESA, image by AOES MedialabRosetta flies above Comet 67P/Churyumov–Gerasimenko in this 2013 artist’s impression. Credit: ESA–C. Carreau/ATG medialabArtist’s impression (from 2013) of the Philae lander on the surface of Comet 67P/Churyumov-Gerasimenko. Credit: ESA/ATG medialab
Artist's impression (not to scale) of the Rosetta orbiter deploying the Philae lander to comet 67P/Churyumov–Gerasimenko. Credit: ESA–C. Carreau/ATG medialab.
Little Philae is awake! ESA sent a wake-up call to the 100-kg (220-lb) lander riding aboard the Rosetta spacecraft this morning at 06:00 GMT, bringing it out of its nearly 33-month-long slumber and beginning its preparation for its upcoming (and historic) landing on the surface of a comet in November.
Unlike Rosetta, which awoke in January via a pre-programmed signal, Philae received a “personal wake-up call” from Earth, 655 million kilometers away.
Hello, world! ESA’s Rosetta and Philae comet explorers are now both awake and well!
A confirmation signal from the lander was received by ESA five and a half hours later at 11:35 GMT.
After over a decade of traveling across the inner Solar System, Rosetta and Philae are now in the home stretch of their ultimate mission: to orbit and achieve a soft landing on the inbound comet 67/P Churyumov-Gerasimenko. It will be the first time either feat has ever been attempted — and hopefully achieved — by a spacecraft.
After Rosetta maneuvers to meet up with the comet in May and actually enters orbit around it in August, it will search its surface for a good place for Philae to make its landing in November.
With a robotic investigator both on and around it, 67/P CG will reveal to us in intimate detail what a comet is made of and really happens to it as it makes its close approach to the Sun.
“Landing on the surface is the cherry on the icing on the cake for the Rosetta mission on top of all the great science that will be done by the orbiter in 2014 and 2015. A good chunk of this year will be spent identifying where we will land, but also taking vital measurements of the comet before it becomes highly active. No one has ever attempted this before and we are very excited about the challenge!”
– Matt Taylor, Rosetta project scientist
Meanwhile, today’s successful wake-up call let the Rosetta team know Philae is doing well. Further systems checks are planned for the lander throughout April.
Watch an animation of the deployment and landing of Philae on comet 67/P CG below:
