Waspie_Dwarf Posted April 20, 2015 #1 Share Posted April 20, 2015 Rosetta's comet throws out big jet Europe's Rosetta probe has caught its comet quarry in the act of producing a huge jet of gas and dust.The 4km-wide icy dirt-ball known as 67P is now throwing off copious amounts of material as it warms up on its journey in towards the Sun. Rosetta is keeping a safe distance, but continuing to image the evolving body. Read more... 2 Link to comment Share on other sites More sharing options...
toast Posted April 20, 2015 #2 Share Posted April 20, 2015 It would be of interest if this blast may have influenced the trajectory and/or the movement of 67P and if yes, how much. Link to comment Share on other sites More sharing options...
ChrLzs Posted April 20, 2015 #3 Share Posted April 20, 2015 Well, given Rosetta's proximity, it will be immediately obvious if her target is drifting off.. I think the 'copious amounts' comment is a bit misleading - the amounts of mass involved would be tiny, probably insignificant, compared to the total mass, and it's also probably not moving all that fast.. So the momentum change would be immeasurable, I'd guess. Happy to be corrected, tho.. Look out, it's comin' right at us!!!!!!!!!!! Link to comment Share on other sites More sharing options...
Waspie_Dwarf Posted April 20, 2015 Author #4 Share Posted April 20, 2015 It would be of interest if this blast may have influenced the trajectory and/or the movement of 67P and if yes, how much. The orbits of comets are very subtly altered by out gassing like this. Each jet has a tiny, imperceptible, effect on the nucleus, acting like a small thruster. With multiple jets acting in different directions and providing variable thrust it is virtually impossible to determine the effect of an individual jet. What it does mean is that it is not possible to calculate, with absolute precision, the future orbital parameters of a comet. The longer the orbit the larger the uncertainty in the calculation of the next perihelion. For a comet with a very short orbital period like 67P/Churyumov–Gerasimenko it will (6.45 years) it will make only a tiny difference. For a comet with a longer orbital period it can make weeks or months of difference, for example Halley's Comet has an orbital period that has varied between 75 and 76 years over the last 3 centuries. 2 Link to comment Share on other sites More sharing options...
+Noteverythingisaconspiracy Posted April 20, 2015 #5 Share Posted April 20, 2015 It would be of interest if this blast may have influenced the trajectory and/or the movement of 67P and if yes, how much. The article says that the outgassing moves at 8 m/s. Compared to a good rocket engine, which has an exhaust velocity of 4500 m/s, this is likely to have a very limited effect on the comet. Without knowing the amount of gas escaping in the jet, and the exact mass of 67P, I can't calculate how much it will effect it. But if you know those numbers, you can use Tsiolkovskys rocket equation to find out: http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation 1 Link to comment Share on other sites More sharing options...
Waspie_Dwarf Posted April 20, 2015 Author #6 Share Posted April 20, 2015 The article says that the outgassing moves at 8 m/s. Compared to a good rocket engine, which has an exhaust velocity of 4500 m/s, this is likely to have a very limited effect on the comet. Yes but it's probably better to think of it more like ion drive than a rocket engine. A small thrust but working over weeks or months. But if you know those numbers, you can use Tsiolkovskys rocket equation to find out: http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation Whilst you could use those equations to estimate the thrust that the jet would produce it would not give you a real-case answer. The problem here is that generally a rocket will thrust in one direction. The cometary nucleus is rotating which means that unless the jet is exactly aligned with one of the comets poles the calculation is going to be far more complicated than that. On top of this there is other out-gassing from other regions thrusting in different directions all of which would need to be taken into account to get anything close to a realistic answer as to the actual effect of this jet. Link to comment Share on other sites More sharing options...
ChrLzs Posted April 20, 2015 #7 Share Posted April 20, 2015 The article says that the outgassing moves at 8 m/s. Compared to a good rocket engine, which has an exhaust velocity of 4500 m/s, this is likely to have a very limited effect on the comet. Without knowing the amount of gas escaping in the jet, and the exact mass of 67P, I can't calculate how much it will effect it. But if you know those numbers, you can use Tsiolkovskys rocket equation to find out: http://en.wikipedia....rocket_equation Notwithstanding Waspie's comments, you know that Unexplained Mysteries has come of age when someone rolls out the words "you can use Tsiolkovsky's rocket equation".. For further reading, try this excellent page (even tho NASA can't spell "tyranny" in the URL..). Link to comment Share on other sites More sharing options...
Waspie_Dwarf Posted April 21, 2015 Author #8 Share Posted April 21, 2015 you know that Unexplained Mysteries has come of age when someone rolls out the words "you can use Tsiolkovsky's rocket equation".. Oh yes Link to comment Share on other sites More sharing options...
Merc14 Posted April 22, 2015 #9 Share Posted April 22, 2015 The next few months are going to be fun to watch! Link to comment Share on other sites More sharing options...
Waspie_Dwarf Posted April 22, 2015 Author #10 Share Posted April 22, 2015 The next few months are going to be fun to watch! I think my previous post serves as an adequate response to this too. Link to comment Share on other sites More sharing options...
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