Spacecraft Trajectories and Dynamics

[Chuft-Captain]

A few quick calcs: (forgetting Einstein for a moment)

Code: Select all

acceleration:               20 km/s/s     20 m/s/s
===============================================
Time to lightspeed:          ~4 hrs     173 days
Distance travelled:          15 au     150,000 au (1/4 ly)


Actually, this discussion suggests a new Celestia feature.
The A and Z keys currently increase and decrease velocity.
What about another mode (spacecraft mode) where you increase or decrease (or set) acceleration instead of velocity, so the velocity would keep increasing until you set it back to zero (MECO).

I'm only half joking now. I actually think this would be quite a cool feature, and prob. not too hard to implement.

This should also be "scriptable", so you could script engine-burns,
eg.. 20 m/s/s for 10 secs.

[Apollonian]

OK, how would I go about modifying the trajectory of an already existing mission? For instance, I want to somehow get Voyager 1 to encounter Pluto. Any help would be greatly appreciated. Thanks!

J P

For right now, unless you have a working knowledge of orbital mechanics, this may be quite difficult. However, if you wanted to, you could set up a simulation and eye-ball the initial vectors (which is hard and time consuming, but fun )

I'm working on developing simulation classes which encapsulate a lot of the orbital mechanics so that the trajectories are optimized for the user. My timeframe is somewhere around six to ten months of development time (given that I have other coursework currently).

Currently, I am working on putting together an Earth-Moon simulation. Next will be probably an Earth-Mars simulation. After this, I will work on the generalized interplanetary simulation.

Oh, and in other news, JAT has finally moved its source onto the Sourceforge server since Sourceforge has finally moved to SVN.

[RocketMan@JSC]

Richard,

Here's a couple lunar trajectories I did a while back. The first one is an Apollo Free return trajectory (finite TLI burn only), goes around the moon and comes back to Earth. Date for this one is July 1, 2005 @ 1200 UT in Earth Centered Inertial frame.

The second one starts out about 15 hours away from the moon and does a periapsis adjust 9 hours away, and then does a LOI burn to capture into Lunar orbit. Date for this one is July 3, 2005 @ 2214 UT in Moon Centered Inertial Frame.

http://home.houston.rr.com/mazdarx7/apo ... Return.xyz

and

http://home.houston.rr.com/mazdarx7/mcc_impLOI.xyz

I posted these awhile back on the Motherlode but they have yet to appear online.

They both are cool to watch--hope you like'em.

Scott

p.s. I'm also an UI grad from back in 87

[Apollonian]

Alright, here is an update on progress:

I am almost finishing with midterm exams and anticipating making some significant progress over spring "break" in a couple weeks.

I've finally amassed enough knowledge of optimal spacecraft trajectories to begin implementing some really useful classes which will allow things like:
"I want to start here and go here in this much time"

The trick is to make these sort of things realistic. It's easy to do when you have all the control in the world (first step), not so easy when you are on a budget (NASA). Eventually, I will probably need to implement flyby's to really get a robust interplanetary mission planner.

Hmmm, I am also starting to think that maybe this isn't so much "open source" work so much as "publishable results". So, this is becoming my thesis topic for my Masters. This should help ensure that I have some usable results in the next year.

[tec]

There is a realtime Celestia solution now available at:

http://www.knology.net/~tec

that you guys might want to consider.

The realtime code will let other simulations send the orbital states via UDP to Celestia. I think this will be useful for your application. I could modify the Realtime code to have Celestia send back 'Celestia generated' state (or any other parameters) information if your application needs it.

Tim

[Apollonian]

Nice!!!

I shall have to look at this in more depth at a later time (ack, Final Exams are upon me already).

[Apollonian]

Does anyone know of any fairly nice 3ds models of the proposed Crew Exploration Vehicle and/or (new) lunar lander?

[tec]

Hello everyone,

I have read through this discuss and implemented many of these Celestia requests in my Real-Time software. There is a new Real-Time version 2.0 posted on the my Real-Time web site:

http://www.knology.net/~tec

There are bug fixes and many additions to the Real-Time version 1.1 software as well as a new web site format. I think you will find this Real-Time software helpful in your endevors.

Tim

[DonAVP]

Does anyone know of any fairly nice 3ds models of the proposed Crew Exploration Vehicle and/or (new) lunar lander?

Richard:

I have been reading this thread. Very interesting. I don't have any models or were to get them. I could possible model them if you could provide images-links etc. I use Lightwave and have a number of programs to get the format converted into 3ds. This includes the textures (UV)that would be needed to finish the detial on the craft.

Don

[Apollonian]

http://www.nasa.gov/missions/solarsyste ... i_res.html

[DonAVP]

Richard:

OK I have downloaded the images on the website you provided. I have no idea about scale so I will guess based upon the apollo craft and lunar lander. Although it will be a little bigger. I will go over the NASA site and see what other mission infor I can find as well. If you know if any images or graphics the give straight on or orthogonal(sp) views these would be great for texture mapping. Will post later under this thread with I have something.

Don

[DonAVP]

Richard:

I posted you a private message. I have a model of the CEV.

Don