Current orbital mechanics research?

[MAraujo]

Just wondering if anyone knows what are some current fields of research regarding orbital mechanics. I often fall into thinking that this type of stuff is pretty well understood and thus a dead science. My work often uses characteristics of Earth's and Mars' orbits to understand climate histories, but surely there must be components of the mechenics that are still not well understood.

Is there current research being conducted in orbital mechanics?

What types of phenomena are physicists still trying to explain?

 

[Urwumpe]

Look for Weak-Stability-Boundary, Interplanetary Transport Network and Fuzzy Orbits.

They are not explained, but simple results of the gravity field of our solar system, but they are subject to research because of their advantages. Today, modern super computers allow calculating such trajectories and optimize them, making them available to spaceflight mission planners.

 

[MAraujo]

So the most current work involves the fine tuning and minor fluctuations. I was also wondering about paleo-reconstructions of orbital data. I can get data that describes earth's orbital parameters up to 500,000 years ago, but beyond that there is some disagreement with regard to certainty. Does orbiter work with such complexity? or is the position of earth's perihelion and angle of rotation fixed over long timescales in orbiter? No real application here, just curious.

 

[kwan3217]

Orbiter uses the VSOP87 ephemeris from the french Bureau des Longitudes. It is a curve fit through the best available (at the time) integrated ephemeris, DE200 from JPL.

DE200 in turn was constructed by fitting a best initial condition state vector for all of the planets which are then propagated using the laws of physics including general relativity and the oblateness of the planets. The initial conditions are tuned until each planet passes as close as possible to all included observations, extending back to Kepler's time and including radio timing of spacecraft orbiting, flying by, or landing on the other planets. DE200 is good from 1599 to 2169

VSOP87 is near-perfect (better than 1km for the inner planets) within its applicable range and useless outside. While you can run the model indefinitely into the past or future, it is a curve fit, and only valid over the range of data that is fit through. It progressively degrades the farther away from the data you get. The authors of VSOP-87 claim it is good enough for +-2000-6000 years, depending on which planet you are talking about.

 

[MAraujo]

Holy crap! that method is way more involved than I was expecting. Very interesting, thanks.

 

[gp]

Look at this:

http://chemistry.unina.it/~alvitagl/solex/

prof. Vitagliano has developed a very fast integration method and is able to simulate planet positions for millions of years.

Here in Italy he has regular articles on astronomy magazine and searches for unusual configurations of planets and small bodies.

gp

 

[MAraujo]

Thats really impressive, Ive been working with the same old data since 2004 and didn't even know such a program was around. I haven't come across anything like this in journals, I wounder if people are hesitant to publish work on this scale of orbital reconstructions because of the lack of certainty (hard to test, easy to refute). Or maybe Ive just been looking in the wrong places. Thanks

 

[gp]

this is another program based on numerical integration.

http://orsa.sourceforge.net/