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Presenting the opening plenary presentation at the SPIE Optics and Photonics Conference in San Diego, Professor Artur Chmielewski, the US Rosetta Project Manager, gave a progress report on the mission. In addition to talking about the newly re-awakened Philae lander, he concluded his talk with Thanks to the space agencies that have been helping the Rosetta Project, and a bit of very exciting news, decided just days before his presentation.
... the Rosetta scientists have now determined how they will be completing this mission: "We will be landing the Rosetta orbiter itself on the comet in 2016 so that will also be generating more exciting data. So we are very happy that the partners NASA, European Space Agency and the DLR (German Space Agency), which built the lander, have now gotten all of their ducks in a row."
(Score: 2) by aristarchus on Tuesday August 11 2015, @10:05PM
If you are in orbit around a comet, you can see why you would not want to be on the surface for perihelion. But why would it make sense to land on the comet on the way out from the center of the solar system? Does Rosetta have instruments that require contact with the comet itself? Is this a plan B after Philae's partial failure? And what happens when the comet comes back? Couldn't Rosetta just stay parked in orbit till then? Perihelion is on August 13, by the way.
(Score: 2) by Gravis on Wednesday August 12 2015, @12:14AM
If you are in orbit around a comet...
let me stop you right there because how the fuck are you going to orbit a comet? comets aren't well known for being spheroid or being particularly large.
(Score: 2) by aristarchus on Wednesday August 12 2015, @12:51AM
"Oh, what sad times are these when passing ruffians can say Ni at will to comets. There is a pestilence upon this land, nothing is sacred. Even those who arrange, design, and orbit shrubberies are under considerable economic stress in this period in history." Roger the Rosetta-er
Gravis, heavy, dude! It's your namesake, bro! How much gravity is necessary to orbit, and why does gravity only work with spheroids?
(Score: 2) by Gravis on Wednesday August 12 2015, @01:29AM
How much gravity is necessary to orbit,
gravity is just part of the equation. there are multiple things to consider:
a) mass of the comet (and the satellite since we are being picky)
b) the circumference and speed of an acceptable orbit. no point in going if you tools don't work from X meters away
and why does gravity only work with spheroids?
gravity works will all shapes and materials which is the problem if you want a stable and predictable orbit. i mean, you dont know the composition of and elemental distribution in the comet, how the hell do you expect to calculate a proper orbit?
bottom line: there are too many unknowns that present an unnecessary risk which would jeopardize the mission in a big way and you lose the ability to analyze the content of the comet which is half the reason for going!
(Score: 1, Informative) by Anonymous Coward on Wednesday August 12 2015, @02:16AM
It is already in orbit about the comet and has been for over a year now. The distance and speed of the orbit are largely dictated by Mr. Kepler, which is about 25 km and a few cm/sec.
And we've got a two-body problem here; stable orbit. Comet composition and mass distribution don't matter. Rosetta orbits about the comet center-of-mass, regardless of how it is distibuted. The largest perturbations to its orbit is solar pressure and getting hit by an unlucky outgassing event from the comet.
(Score: 2) by aristarchus on Wednesday August 12 2015, @05:22AM
It is already in orbit about the comet and has been for over a year now. The distance and speed of the orbit are largely dictated by Mr. Kepler, which is about 25 km and a few cm/sec.
Which allows me to repeat my original question: what is the advantage to parking the Rosetta on the surface of the comet, instead of remaining in orbit?
(Score: 2) by hubie on Wednesday August 12 2015, @12:16PM
I would surmise that it is due to a combination of issues: it met its primary mission goals, it will have met its extended mission goals, and after its extended mission, it will be too far from the Sun for the solar panels to power the craft. On its return in five or so years, there might be a low probability that the spacecraft would be recoverable. I'm sure they weighed all that, as well as the likelihood of receiving continuing funding out that far, against the science return (and PR) of what you'll get if you let it land on the comet.