July 18, 2014
Rosetta Reveals Rubber-Duck Shape Of Comet 67P/Churyumov-Gerasimenko
redOrbit Staff & Wire Reports - Your Universe Online
New photos of 67P/Churyumov-Gerasimenko (67P/C-G) obtained by ESA’s Rosetta Probe reveal the comet has an extremely irregular shape and is likely a contact binary, meaning that it is comprised of two distinct parts that gravitate towards each other and ultimately form a single odd-looking body.
Rosetta, which is on a historic mission to orbit and land on the comet, captured the image from a distance of 12,000km using its Rosetta's OSIRIS narrow angle camera on Monday, NASA officials explained in a statement. Since then, the spacecraft has moved even closer to 67P/C-G’s nucleus and is less than 9,000km away, giving it an even better look at its target.
The ESA probe was also able to obtain a second image and a movie that used a technique known as “sub-sampling by interpolation” to remove the pixilation and smooth it out, the agency noted. However, using this technique makes the surface texture look smoother than it actually is, so any regions that appear to be brighter or darker could be false interpretations at this point.
While this particular issue cannot be resolved until Rosetta gets closer to the comet, the ESA noted that the movie features a series of 36 interpolated images each separated by intervals of 20 minutes. This compiled footage “certainly provides a truly stunning 360-degree preview of the overall complex shape of the comet,” the agency said. “Regardless of surface texture, we can certainly see an irregular shaped world shining through.”
That unorthodox shape has already drawn comparisons to a rubber duck by some, including BBC News, and to a “strange-looking potato” by mission scientist Matt Taylor in comments made to the Associated Press (AP).
Previously, 67P/C-G was believed to have a more compact and well-rounded shape, but the movie footage definitely supports the presence of two definite and distinct components to the comet, the ESA noted, adding that one of those segments appears to be somewhat elongated, while the other appears to be more bulbous.
Since astronomers previously believed it had a more compact and well-rounded shape, Taylor told the AP that the discovery could be a contact binary with a distinct body and head was “an exciting surprise.” However, as the BBC pointed out, it is not clear yet if the comet is actually comprised of two distinct objects that are just touching due to gravity, of if they have actually been melted together as the result of a low-velocity impact.
The ESA scientists are “not rushing to judgment,” the British news agency added. If the components are distinct, it must be determined if they originated from the same body or were originally parts of unrelated objects that met at a later date. Likewise, researchers must consider the possibility that the unusual shape is due to uneven ice loss or impact with other space objects, and whether or not this will have an impact on Rosetta’s attempt to land on the comet.
“We currently see images that suggest a rather complex cometary shape, but there is still a lot that we need to learn before jumping to conclusions,” said Rosetta Mission Manager Fred Jansen. “Not only in terms of what this means for comet science in general, but also regarding our planning for science observations, and the operational aspects of the mission such as orbiting and landing.”
“We will need to perform detailed analyses and modeling 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,” he added. With the August 6 rendezvous rapidly approaching, Jansen said that these questions “will soon be answered.”