OHM Trajectories

[OrbitHangar]

Author: evilfer

Trajectories is a tool to plan and simulate missions through the solar system. The objective is that the mission could be later flown in Orbiter.

Currently, Trajectories implements the basic functionality: you can define a mission, simulate it, and visualize the route. However, the tool does not provides support in creating the mission plan. I intent that future versions will include several aids that facilitate setting up complex missions, for instance those involving L-points (as in the JWST mission) or low energy transfers (as in the Hiten mission).

Other features not (yet) implemented:
- Relativistic effects,
- Aerobraking,
- etc...

Please note that the download linked here does not contain the necessary data to compute the positions of planets and moons in the Solar System. Data must be retrieved from Naif's SPICE system (instructions can be found in the link below).

The required files are about 640MB.

Trajectories page at SF, installation instructions and manual (under construction):
http://sourceforge.net/apps/mediawiki/trajectories/

Also, please note that this software is not only work in progress but also "learn in progress". I mean that I'm learning a lot about astronomy as I'm developing this tool; as a result of this, Trajectories is bound to have astronomy mistakes (in the use of terms, references, etc.).

Corrections, suggestions and reviews are very appreciated .






DOWNLOAD

 

[Wishbone]

A-ha! Suppose we'll be monitoring the development of this tool closely. For those who already installed Trajectory Optimization Tool or ajaja's spice.dll, the size of files to download is actually VERY small: 1002K for Trajectories and 147K for the star catalog.

And of course, implementing low-thrust planning options will be very much appreciated!

---------- Post added at 03:35 PM ---------- Previous post was at 03:16 PM ----------

The program requires MS VC 10.0 runtime (msvcr100.dll and msvcp100.dll). It is better to include them for the benefit of non Windows7 non MSVC2010 users.

 

[evilfer]

A-ha! Suppose we'll be monitoring the development of this tool closely. For those who already installed Trajectory Optimization Tool or ajaja's spice.dll, the size of files to download is actually VERY small: 1002K for Trajectories and 147K for the star catalog.

And of course, implementing low-thrust planning options will be very much appreciated!

[/COLOR]The program requires MS VC 10.0 runtime (msvcr100.dll and msvcp100.dll). It is better to include them for the benefit of non Windows7 non MSVC2010 users.

Hi, thank you for your post . I uploaded a new version including the .dll files you indicated.

About the finite thrust maneuvers, I have one question. The maneuver should be defined at a time (T0), which determines the direction of the prograde, offplane and outward vectors and therefore the direction of thrust. This direction of thrust is kept constant during the maneuver.

Since the maneuver takes time, should the burn begin before T0? Or is it ok to let the maneuver start at T0? My best guess is that it should start at a time T1 with T1<T0, so that half of the acceleration is achieved before T0, and the other half after T0 (this means that, in the case of finite non-weightless fuel, the burn will end at T2, with T2 - T0 != T0 - T1).

I'm not sure this is what TransxMFD does :S. Anyway, I think the more natural interface is to let the user choose only T0 and the thrust power, having the simulator calculate T1 and T2 automatically. Would you consider this a good idea?

Eloy

 

[Wishbone]

The most useful convention for long burns (not with very low-thrust ion engines or solar sails) is to have the user mark the time and dV vector for an impulse instantaneous burn and let the program find the arrangement that has the same post-burn orbit as the one with impulse burn, but with the least fuel expenditure.

Re: GUI for the utility - check diagonal lines from top left to bottom right points. :tiphat:

You may also find it useful to read the source code from TransX...

 

[evilfer]

The most useful convention for long burns (not with very low-thrust ion engines or solar sails) is to have the user mark the time and dV vector for an impulse instantaneous burn and let the program find the arrangement that has the same post-burn orbit as the one with impulse burn, but with the least fuel expenditure.

Re: GUI for the utility - check diagonal lines from top left to bottom right points. :tiphat:

You may also find it useful to read the source code from TransX...

Again, thank you for your answer. Obviously that burn management would be great: you could change the burn mode or the ship parameters without affecting the mission plan: the maneuvers would result in the same outcomes. However, I can't figure out how to implement burns that would result in exactly the same orbit as an instantaneous impulse.

So, checking the source code of TransxMFD, which was the most sensible thing to do in the beginning, I got the following formula for the burn start:

burnStartTime = ifItWereAnImpulseTime - burnDuration + burnDuration / (2 + burnDuration * fuelConsumption / initialMass)
where [fuelConsumption] = Kg/s

In the case of infinite fuel, this actually means that half the burn happens before impulseTime, and the other half after it. In the case of finite non-weightless fuel, the burn would start earlier.

This burns do not result in the same orbit as an instantaneous impulse . Anyway, this is what I will use. Next version 0.0.4 will include at least the three thrust modes, ship parameter configuration, plane change maneuvers, and I think also searchs for body orbit plane cuts.

Ah! About the diagonal lines, I don't get any in my laptop. Could you please indicate me where they occur, so I can fix them?

 

[Wishbone]

Diagonals are in all the windows and (AFAIR) window titles: cannot post the screenshot now, but suppose the bug is in the code responsible for drawing window rectangle, it may be a problem of sequencing the four points.

 

[evilfer]

Diagonals are in all the windows and (AFAIR) window titles: cannot post the screenshot now, but suppose the bug is in the code responsible for drawing window rectangle, it may be a problem of sequencing the four points.

Again about the diagonal lines :S, the code that draws the window rectangle is the same that draw the rectangles for buttons and text fields. Do the diagonal lines happen in those widgets as well? What color are the lines?

I made a little change in the code, I hope it works well in next version.


Another thing, I'd like to ask for recommendations before uploading a new version. Thanks to the feedback received in another thread in this same forum , I'm clear about the physics model for the finite thrust maneuvers. Now I have to finish the ship configuration window. Here is the current prototype:

This window has the following parameters:

- Ship mass [kg]
- Thrust [N]
- DeltaV [m/s] (the rocket capability for the whole mission)
- Initial fuel mass [kg]
- Isp
- Max fuel consumption [kg/s] (at max thrust)

Currently you can configure the first 4 parameters; Isp and consupmtion are calculated by the simulator. The questions are:
- what parameters would you like to see?
- which ones would you prefer to input manually?

I guess that Isp should also be editable. In this case, Isp, fuel mass and deltaV affect each other.
- When you modify one of these, which other should be automatically recalculated by the simulator?

 

[Wishbone]

Three methods selectable via radio buttons:
1) Max thrust, Isp, Fuel Mass, Ship mass w/o fuel
2) Max thrust, Isp, total dV
3) Max thrust, Isp, fuel fraction

I suggest looking up the following software for GUI and modelling ideas:
GMAT - http://sourceforge.net/project/showfiles.php?group_id=201258&package_id=239508&release_id=629854
STA - http://sourceforge.net/projects/sta/files/
Gravity Simulator - http://www.orbitsimulator.com/gravity/articles/link.html

 

[evilfer]

Three methods selectable via radio buttons:
1) Max thrust, Isp, Fuel Mass, Ship mass w/o fuel
2) Max thrust, Isp, total dV
3) Max thrust, Isp, fuel fraction

I suggest looking up the following software for GUI and modelling ideas:
GMAT - http://sourceforge.net/project/showfiles.php?group_id=201258&package_id=239508&release_id=629854
STA - http://sourceforge.net/projects/sta/files/
Gravity Simulator - http://www.orbitsimulator.com/gravity/articles/link.html

Thank you for the links. For some reason, before starting my own I had found only the last of those three. I don't think I'll look much into the first two, they seem too good, and don't wanna just copy other software, I'll just continue to see where I get .

 

[Wishbone]

Attaching a piccie. It looks like all rectangular surfaces have this diagonal problem, even the spacecraft RED CUBE...

A minor linguistic nitpick - origin is the English word you're after, while Origen is the heretic...

 

[evilfer]

Attaching a piccie. It looks like all rectangular surfaces have this diagonal problem, even the spacecraft RED CUBE...

A minor linguistic nitpick - origin is the English word you're after, while Origen is the heretic...

Coming back to this, after a long time I found the same problem in my friend's computer. It was solved by updating the graphic card drivers. Updating them should be harmless anyway or even good, so if anyone checks that Trajectories works with updated drivers it'd be very helpful.

Don't have much time to code these days, but I'll try to continue the development. I want to implement some kind of assistant for Hohmann transfer orbits and for slingshots.


Thank you for the help with the bug and with English as well!!

 

[wingnut]

There is no installation_path/kernel_download folder and download_all_kernels.bat file in the version I downloaded and the links from the readme are dead.

Could anyone point me to a location where I could download the required Kernels please?

Nevermind, I figured it out myself and downloaded the files by browsing manually through http://naif.jpl.nasa.gov/pub/naif/generic_kernels/.

 

[evilfer]

There is no installation_path/kernel_download folder and download_all_kernels.bat file in the version I downloaded and the links from the readme are dead.

Could anyone point me to a location where I could download the required Kernels please?

Nevermind, I figured it out myself and downloaded the files by browsing manually through http://naif.jpl.nasa.gov/pub/naif/generic_kernels/.

Sorry for not answering, I've been away from this forum for quite a while. I'm glad you found the kernels, and hope you could try trajectories.

By the way, I retook the development of this tool this year. I'm rewriting the GUI and refactoring the backend code to make it more flexible. Curiously, even it its poor state trajectories still gets a handful of downloads every week...