Determining orbit trajectories

[Doug Hortvet]

Am most interested in the methods JPL uses to calculate orbits of NEOs and how frequently
the data used to calculate the orbits is updated for close approach objects.

Specifically:

1. Are JPL's algorithms proprietary or published?
2. If published - where can they be accessed?
3. What is the type and source of the data used in orbit determination?

Thanks in advance for responses / comments.

Regards,

Doug

[Jeff Findley]

In article <6lofh8l99ctbj96m6...@4ax.com>,
dhor...@pdq.net says...

>
> Am most interested in the methods JPL uses to calculate orbits of NEOs and how frequently
> the data used to calculate the orbits is updated for close approach objects.
>
> Specifically:
>
> 1. Are JPL's algorithms proprietary or published?

Orbital mechanics isn't proprietary. I took a 500 level class in
Orbital Mechanics at Purdue in the early 1990's. From my dim memory, my
professor worked prior at JPL designing gravity assist trajectories for
unmanned spacecraft.

> 2. If published - where can they be accessed?

Google "orbital mechanics" for a start.

> 3. What is the type and source of the data used in orbit determination?

Position and velocity obtained from radar and/or optical observations.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

[Steve Willner]

In article <6lofh8l99ctbj96m6...@4ax.com>,

Doug Hortvet <dhor...@pdq.net> writes:
> 1. Are JPL's algorithms proprietary or published?

The underlying theory is general relativity, which is widely
published. I'd expect many of the numerical methods to be published
as well, but I don't know for a fact that they are. Actual computer
codes are probably being tweaked all the time, and I wouldn't expect
them to be published, but you could try a FOIA request. An informal
request to a JPL contact might be simpler and quicker.

> 2. If published - where can they be accessed?

Results -- ephemerides and such -- are available at
http://ssd.jpl.nasa.gov/?horizons

I expected to find more information about methods than I did, but
maybe I didn't search well enough.

> 3. What is the type and source of the data used in orbit determination?

Depends on the object, but in general I'd expect JPL to use all
available data. There are several telescopes dedicated to finding
and tracking solar system objects, and there's an IAU Minor Planet
Center charged with compiling asteroid and comet observations.

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