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Rosetta Spacecraft Lands Philae on Duck Shaped Comet 67P's Head In the First Comet Landing In Human History

    Posted: 12 November 2014
Rosetta blog
target on comet churyumov gerasimenko's head
Comet 67P Churyumov Gerasimenko. Philae aimed to land on comet's head but bounced 4 times after making contact with comet.

January 7th, 2015: The comet lander Philae is "missing." Rosetta which is still orbiting Comet Churyumov-Gerasimenko is not able to detect or see Philae on the comet. Photographs of the comets surface from the spacecraft Rosetta are being scanned to try to find the missing comet-lander Philae.

Orbit: The curved path of a celestial object or spacecraft around a star, planet or moon, especially a periodic elliptical revolution.

European Space Agency (ESA) scientists behind the Rosetta Mission are attempting, for the first time in human history, to take samples from the surface of a comet. To do this, they first have to land their robot called Philae on the surface of the comet. The comet is as big as an island and tumbling through space. It would be an amazing achievement for ESA and all of the scientists and aerospace engineers involved to successfully land Philae. It will be known in a few hours, on Wednesday November 12, 2014.         Rosetta was launched in March of 2004. The spacecraft has been in space for over a decade and depends on solar panel like wings - that are each 64 meters squared.

         “It will take around 7 hours from the time Philae separates from the Rosetta mother craft until for the 1st time ever, a Lander will be on the surface of a comet,” said Koen Guerts of DLR aerospace in Germany, who is an engineer for the Philae Lander. The “comet” is much different than astronomers expected it to look from far away through their telescopes.

Philae the comet lander
Artist's conception of Rosetta spacecraft dropping Philae on the surface of the comet.

Scientists want to take samples of the Comet Churyumov Gerasimenko 67P so that they can know what the comet is made of….

Comet 67P looks like two comets stuck together. Close up images from Rosetta’s imaging system OSIRIS reveal a third smaller protrusion on the duck shaped rock- making the shape of the comet “multi-hazard” because if it were to hit something it would be like being struck by 3 rocky objects at once. Rosetta, Philae, and the comet are about 319 million miles away from the center of the Earth. Comet 67P is currently moving towards the Sun on its elliptical cometary orbit.

For pixel information this quote was provided in a recent ESA blog about Rosetta's imaging system called OSIRIS:

Comet chasing spacecraft Rosetta had to use a series of triangular maneuvers, each leg being several hundred feet long, to get into orbit around the comet. It took several weeks. Any idea why the Rosetta spacecraft had to use triangular maneuvers to get into orbit around the comet?  There could be more than one answer and ... the information may be revealed in coming days or weeks by the ESA scientists. One hypothesis could be that it is due to the comet's unspherical shape and the difficulty of judging a circular orbit as a result of that knobby shape. Why land Philae on the ducks head and not the body which is larger than the head? So far that has not been explained to the public by the Philae scientists.

“Unlike standard cameras that encode information in 8 bits per pixel and can thus distinguish between 256 shades of gray, OSIRIS is a 16-bit camera. This means that 1 image can comprise a range of more than 65,000 shades of gray - much more than a standard computer monitor can display.”


One news source called the comet 67/P “a time piece,” like a watch, meaning its rotation is periodic and things can keep time to it, such as the Rosetta spacecraft orbiting around it.  Rosetta’s orbit around the comet must be properly calculated.

This fast moving rotating comet is not just shooting aimlessly through space- it has an orbit. A random flying chunk of ice from the depths of space would not seem to have an orbit. It has not been stated so far at what speed the duck shaped comet is tumbling at. 

Everything happening on Philae will be known on Earth about half an hour later. Due to the distance of 319 million miles, the signal must be relayed.

Philae Lander
Above: Philae Lander is about as big as a washing machine and weighs 220 lbs or 100 kg. There is a harpoon on the bottom of it that will shoot into the comet and ice screws on its feet to help it stick in the comet.

Ice-screws, harpoons, and drills on Philae will try to grip into the comet and their success depend on the hardness of the comet’s surface.  Philae will partly use it’s own weight about 100 kg or 45 lbs., to make a landing with the comet and shoot its harpoon into the comet’s surface from the bottom of Philae as well and plant the ice screws from Philae's feet. There are thrusters on the top of Philae to assist in this process of pushing down onto the comet’s surface for the purpose of drilling into the surface and performing a ground analysis.

The drill is contained within a tower concealed within the walls of Philae.  The tip of the drill will put a sample of the ground on the comet into tiny centrifuge-like ovens inside the tower for examining.

Philae has 7 cameras mounted on the outer solar-arrayed walls of Philae  that will take panoramic view of the ground area around Philae out to the comet’s horizon possibly into space. A camera mounted on the bottom of Philae (next to the harpoon) will take photographs “whilst descending to give unprecedented images never seen before,” says Koen Guerts.

A hammering device on top of a thermometer 30 cm long will try to tap the thermometer completely into the comets surface. The Philae cube shaped lander has an edge length of roughly 1 meter on each side. It has batteries and solar panels all around the main body so that is can operate for several months on the comet’s surface.

It is interesting that DLR is using radio wave technology to study Comet Churyumov Gerasimenko. When the Rosetta is on the other side of the comet from the Lander, completely out of sight from Philae- the instrument which has an antennae on Rosetta and on Philae – sends out a signal and will allow the scientists to make some observations about the electrical nature of the comet 67P Churyumov Gerasimenko.

“Also equipped with an additional set of Antennas which are not used to communicate with Rosetta but they are part of an instrument that is both on Philae and Rosetta orbiter- and the 2 instruments or 2 antennae communicate with each other not when Rosetta is in sight but when Rosetta is on the other side of the comet with respect to Philae and the radio waves are traveling through the comet so that we can derive the properties of the inside of the comet.” - Koen Guerts, DLR

By Andrea Boggs

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Astronomers Churyumov & Gerasimenko in 1969.
Above: Soviet astronomers Svetlana Gerasimenko &Klim Ivanivich Churyumov who discovered the Comet 67P in 1969.



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Above: An engineer from DLR, the German aerospace firm that made Philae, describes the different tools and instruments that are on Philae.


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