Mission To Sedna, space mission to sedna |
Mission To Sedna, space mission to sedna |
Jan 13 2008, 12:51 PM
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#1
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Junior Member Group: Members Posts: 27 Joined: 27-September 07 From: Tampere, Finland Member No.: 3919 |
I have tried to search but could not see any serious planning of sending a fly-by mission to Sedna. Does anyone have any info if the scientific community is planning such...?
In my opinion, Sedna would be very interesting target, far more interesting than any KBO etc. The fact that it spends most of the time outside heliopause under the influence of cosmic rays during aphelion could reveal some interesting results and also the reddish colour it has might be worth investigating. And good for us, at the moment it is approaching its closest point to Sun on its orbit, so mission to Sedna would not be such a big effort if done e.g. a'la NH with Jupiter gravity assist...? Maybe possible NH2 could be sent that direction.......? Any comments, any info? Especially the fact that it is a body from outside the heliopause, could that add some interest towards it? -------------------- Spamming the Solar System with greetings since 1997!
(New Horizons, Huygens, Opportunity/Spirit, Deep Impact, Dawn, Phoenix, Selene... to name a few) :) |
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Jan 13 2008, 08:33 PM
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#2
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Senior Member Group: Members Posts: 1582 Joined: 14-October 05 From: Vermont Member No.: 530 |
Jupiter-Sun gravity assist can get you going even faster. Of course the flyby will then be extremely brief.
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Jan 13 2008, 08:46 PM
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#3
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
How can you use Sun in a gravity assist? That's like using Earth in a gravity assist to get to the Moon. Unless you're thinking of a solar sail or ion engine providing delta-V during the Sun "flyby" in which case it makes a bit sense.
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Jan 14 2008, 02:34 AM
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#4
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Senior Member Group: Members Posts: 1582 Joined: 14-October 05 From: Vermont Member No.: 530 |
How can you use Sun in a gravity assist? That's like using Earth in a gravity assist to get to the Moon. Unless you're thinking of a solar sail or ion engine providing delta-V during the Sun "flyby" in which case it makes a bit sense. Can't say I really know all the details-- Any gravity assist needs some sort of delta-V in the well, right? I think the Jupiter-Sun dual gravity assist was suggested for some interstellar probe. And I think it jettisoned a sun-shield when passing the sun, so there was delta-mass as well. |
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Jan 14 2008, 09:18 AM
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#5
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
Can't say I really know all the details-- Any gravity assist needs some sort of delta-V in the well, right? Gravity assists work by changing speed relative to a third body. The speed w/respect to the body you're flying by doesn't change and this is what I meant. Sedna is in solar orbit so passing by the center body - the Sun will not give you any free delta-V. Jupiter works for other targets because it's not the center body of the system, rather it is in orbit around the Sun and you can steal a little bit of that energy. I suspect the Sun flyby scenario actually doesn't imply a passive flyby, but a thrusting period (solar ion engine?) during a very low perihelion. This does boost your speed significantly, because you're deep in the gravity well and for every km/s of delta-V you burn, you get a higher hyperbolic excess velocity than burning that same delta-V far out. That's why for example New Horizons didn't need to get that obscene delta-V at Earth-Jupiter injection. Rather, a modest increase in ejection velocity out of parking orbit makes you spend less time in Earth's gravity well and gives you higher hyperbolic velocities. It sounds counterintuitive, but it works. If we really had to provide every single km/s our planetary probes get by the launch vehicle, we wouldn't be getting very far. -------------------- |
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