Rosetta’s Comet Races Through Space

Space Enthusiasts,

Isn’t it fun to track asteroids,comets, and ships in space. I’ve been a space fan since my youth. This includes scifi books, movies, and TV shows; Star Trek being one of my all time favorites.

COMET SINKHOLES GENERATE JETS

COMET SINKHOLES GENERATE JETS

Another thing I’m keeping a close eye on is the comet, Rosetta. It’s racing through our solar system along with everything else. Here’s some information from Nasa’s website. nasa.gov. about Rosetta’s Comet.

A number of the dust jets emerging from Rosetta’s comet can be traced back to active pits that were likely formed by a sudden collapse of the surface. These ‘sinkholes’ are providing a glimpse at the chaotic and diverse interior of the comet.

Rosetta has been monitoring Comet 67P/Churyumov–Gerasimenko’s activity for over a year, watching how its halo of dust and gas grows as the comet moves closer to the Sun along its orbit.

Active regions in Seth medium

Active regions in Seth medium

From a distance of a few hundred kilometres, Rosetta observes an intricate pattern of the dust jets emitted from the nucleus as they stream out into space. But now, thanks to high-resolution images from the OSIRIS camera from distances of just 10–30 km from the comet centre last year, at least some of these dust jets can be traced back to specific locations on the surface, the first time this has ever been seen.

In a study reported today in the science journal Nature, 18 quasi-circular pits have been identified in the northern hemisphere of the comet, some of which are the source of continuing activity.

The pits are a few tens to a few hundreds of metres in diameter and extend up to 210 m below the surface to a smooth dust-covered floor. Material is seen to be streaming from the most active pits.

“We see jets arising from the fractured areas of the walls inside the pits. These fractures mean that volatiles trapped under the surface can be warmed more easily and subsequently escape into space,” says Jean-Baptiste Vincent from the Max Planck Institute for Solar System Research, lead author of the study.

Scientists analysing the images think that the pits are formed when the ceiling of a subsurface cavity becomes too thin to support its own weight and collapses as a sinkhole. This exposes the fractured interior of the comet, allowing otherwise hidden material to sublimate, thus continuing to erode the pit over time.

Active pits medium

Active pits medium

“Although we think the collapse that produces a pit is sudden, the cavity in the porous subsurface could have growing over much longer timescales,” says co-author Sebastien Besse, of ESA’s ESTEC technical centre in the Netherlands.

The authors suggest three possible ways the voids are formed.

One idea is that they have existed since the comet itself formed, as a result of very low-speed collisions between primordial building blocks tens to hundreds of metres in size. The collapse of the roof above such a void could then be triggered through weakening of the surface, perhaps by sublimation or via seismic shaking or impact from boulders ejected from elsewhere on the comet.

Another possibility is the direct sublimation of pockets of volatile ices like carbon dioxide and carbon monoxide below the surface, heated by the warmth of sunlight penetrating an insulating top layer of dust.

Alternatively, sublimation could be driven by the energy liberated by water ice changing its physical state from amorphous to crystalline then sublimating the more volatile surrounding carbon dioxide and carbon monoxide ices.

This is fascinating stuff. While we’re on the name Rosetta, there’s also a satellite by that name. I took this information from nasa.gov as well.

Rosetta the satellite began her mission of traveling the galaxy in March 2004. The journey began in with an Ariane-5 launch from Kourou in French Guiana. The three-tonne spacecraft was first inserted into a parking orbit, before being sent on its way towards the outer Solar System.

Unfortunately, no existing rocket, not even the powerful European-built Ariane-5, has the capability to send such a large spacecraft directly to Comet 67P/Churyumov-Gerasimenko.

Instead, Rosetta will bounce around the inner Solar System like a ‘cosmic billiard ball’, circling the Sun almost four times during its ten-year trek to Comet 67P/Churyumov-Gerasimenko.

Along this roundabout route, Rosetta will enter the asteroid belt twice and gain velocity from gravitational ‘kicks’ provided by close fly-bys of Mars (2007) and Earth (2005, 2007 and 2009).

Rosetta Earth Fly By

Rosetta Earth Fly By

Rosetta first travels away from its home planet and then encounters Earth again, a year after launch, in March 2005.

Rosetta remains active during the cruise to Earth. The fly-by distance is between 300 and 14 000 kilometres. Operations mainly involve tracking, orbit determination and payload check-out. Orbit correction manoeuvres take place before and after each fly-by.

After the first fly-by of Earth in March 2005, Rosetta heads to Mars and then returns to Earth twice in November 2007 and November 2009 for its second and third fly-bys of our planet.

Rosetta Swings By Mars

Rosetta Swings By Mars

Rosetta flies past Mars in February 2007 at a distance of about 200 kilometres, obtaining some science observations.

An eclipse of Earth by Mars lasts for about 37 minutes, causing a communication black-out.

The spacecraft goes into passive cruise mode on the way to the asteroid belt. Rosetta observes the asteroids from a distance of a few thousand kilometres. Science data recorded on board are transmitted to Earth after the fly-by.

How Rosetta wakes up from deep space hibernation. After a large deep-space manoeuvre, the spacecraft goes into hibernation. During this period, Rosetta records its maximum distances from the Sun (about 800 million kilometres) and Earth (about 1000 million kilometres). Rosetta wakes up from deep space hibernation on 20 January 2014.

Our Sun by Hubble Telescope

Our Sun by Hubble Telescope

Rosetta arrives at comet.

In May 2014, Rosetta’s thrusters begin to brake the spacecraft, so that it can match Comet 67P/Churyumov-Gerasimenko’s speed and orbit.Rosetta finally arrived at the comet on 6 August 2014. It is currently making the exciting transition to global mapping, lander deployment and the comet chase towards the sun.

This is so exciting; Rosetta’s Comet is terrific. I’ll continue to follow the comet right here.

Also check out my Maxx Zeqster blog at: https://detectivemaxxzeqsterscreepycrawlyamazingadventures.wordpress.com/ .

Thanks for tuning in. J. A. Ireland.

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