Advanced Question How to use GMAT with IMFD?

[GodAtum]

I'm currently trying to attempt to use GMAT to calculate dVf, dVp and dVo values to input into IMFD. I'm using the Ex_LunarTransfer.script. For the included craft called "Sat", I input the dry mass = 266400 (of the XR5). After running, I get the values of

Delta V Vector:
Element 1 (dVf): 0.1460772782317 km/s
Element 2 (dVp): 0.0460426758920 km/s
Element 3 (dVo): 0.1169439002362 km/s

These don't make any sense as when I input them into IMFD they are way lower then it should be.

 

[GodAtum]

Is anyone able to help please. My scenario file and GMAT save are attached.

I burn prograde @ 3.121k on date 1/1/2025.

However it did not go anywhere near the moon, unlike what GMAT said it would.

 

[Boxx]

With what you provided, there is no way to reach the Moon. The lack of unit in GMAT makes the script quiet cryptic... but if you are not given a delta-V close to 3km/s then your GMAT setup/request is wrong (see EDIT).

At least at 3150 [sec], your Velocity vector is aligned with the Moon. With only +0.192km/s, you won't leave LEO, for sure (but where is the delta-V you mentioned in GMAT?!). After ca.250s of full thrust, deltaV=+2.87km/s, your new orbit (still elliptical) reaches the Moon's orbit. If you want the Moon to be at your apogee at that time, after 4.7 days, you need to adjust the direction during the TCM to keep the relative velocity to the Moon. In any case, don't forget to KILL ROT before applying the TCM thrust.

(EDIT: for instance "GMAT LOI.GravitationalAccel = 9.81;" seems to me wrong for the Moon and at the Moon)

 

[GodAtum]

Thanks for your reply. I'm new to GMAT and there's very few tutorials on it, so what you said unfortunately makes no sense to me.

All I'm trying to do is get the DG from Earth orbit to the Moon. I've also tried uisng the Ex_LunarTransfer.script (by adjusting the Sat orbital values and mass to match in-game) but that didn't work either.

Would you mind providing a script that will work for Orbiter?