Rosetta

[Wallace]

Soo, has anyone attempted a mission with as impressive a flightpath as the Rosetta spacecraft?

It's been out there for 10 years and has gravity assists coming out the wazzo, here's a little animation showing it's path.

http://sci.esa.int/where_is_rosetta/

click show full path to see it all at once.

What's the most number of gravity assists anyone has got in 1 mission?

[zekes]

three gravity assists? No thank you, KSP transfer nodes are way to impresice to calculate all that at once.

[Sirrobert]

I didn't even know it was possible to gravity assist from the parent body.

Cool

So can anyone explain what exactly those pyramids are? Not exactly understanding triangle orbits

Other question: is Roseta actually orbiting the asteroid, or is it just flying on the same orbit?

Edited August 8, 2014 by Sirrobert

[Wallace]

The 'triangle orbit' is not really an orbit it's moving around the comet using thrusters to redirect it in a triangle pattern which slowly gets smaller and smaller until it is very close and it can finally enter a real orbit. It's because the gravity is so weak, and they don't yet know the exact mass and mass distribution of the comet so they need to map it out before they get in close and enter an actual orbit, I guess moving in a triangle has the least course changes to go around it using thrusters.

Here's how the 'triangle orbit' goes.

[norup]

So can anyone explain what exactly those pyramids are? Not exactly understanding triangle orbits

Other question: is Roseta actually orbiting the asteroid, or is it just flying on the same orbit?

There is a good explanation of the "orbit" on Sixty Symbols

And some interesting numbers on this Wired blog

http://www.wired.com/2014/08/comet-walk/

It appears that Rosetta is not truly orbiting the comet at this time, but rather flying in formation, making a triangular pattern.

The escape velocity is extremely low, only 0.5m/s on the surface, so orbiting at appreciable height would take forever and may not even be practically feasible.

[Monger]

I can't get my head around the multiple gravity assists around Kerbin... err... Earth.

I get the first one. You "just" tilt the Earth's orbit, so you basically still have the same orbital velocity, ergo you have to meet again after one cycle.

The second one is insane. Using Mars to brake, return back to Earths orbit exactly just a little later, to gain enough speed to reach Jupiter... just to swing back and even further. Amazing. I kind of doubt that such a crazy course is man-made. I guess ESA has some software to predict the most efficient paths for all kind of bodies.

[zarakon]

three gravity assists? No thank you, KSP transfer nodes are way to impresice to calculate all that at once.

four

one from earth, then one from mars, then two more from earth

[Sirrobert]

I can't get my head around the multiple gravity assists around Kerbin... err... Earth.

I get the first one. You "just" tilt the Earth's orbit, so you basically still have the same orbital velocity, ergo you have to meet again after one cycle.

The second one is insane. Using Mars to brake, return back to Earths orbit exactly just a little later, to gain enough speed to reach Jupiter... just to swing back and even further. Amazing. I kind of doubt that such a crazy course is man-made. I guess ESA has some software to predict the most efficient paths for all kind of bodies.

Well offcourse.

Real world spaceflight is more like Mechjeb than without Mechjeb. Humans tell the computer what they want to do, the computer calculates it (with help from the humans probably).

And in flight to, after a computer calculated how and what, they tell the computer to do a set of actions, and the computer does those actions at the right time

[Kasuha]

three gravity assists? No thank you, KSP transfer nodes are way to impresice to calculate all that at once.

Rosetta of course made corrections in between those assists. Even in real world it is not possible to send a probe on multiple-gravity-assist path in just one burn.

[cantab]

I don't know the exact number, but I made lots of Duna assists in a bid to reach Jool once. Came so close but ran out of fuel on my final course correction that would have brought me my Jool encounter.

PS: I think the record for real-world craft is probably MESSENGER. One Earth, two Venus, and three Mercury assists before entering Mercury orbit.

Edited August 8, 2014 by cantab

[Heagar]

...snip

I guess ESA has some software to predict the most efficient paths for all kind of bodies.

Of course they have software to calculate it.

But at NASA there was an crasy engineer who wanted to have a sattelites course/orbit (designed originally for a sun observation mission) altered to chase a comet too. The resulting distance was not as close as for Rosetta, but done mostly by hand (The computers where not so good at that times). After a 25 years voage of the sattelite he promises (the guy must be over 80 years by now) that he is able to reroute that sattelite a second time to it's original course.

Because i didn't find that article again so quickly, i searched for a sattelite witch is matching the the story. It may be the ISEE-3.

Edited August 8, 2014 by Heagar