NASA OS Software: The General Mission Analysis Tool (GMAT)

[ElChristou]

...I think it makes sense to at least help promote Celestia if we are collaborating. I should mention that I'm not a NASA employee, so I can't really speak to what can be done beyond that; anything I say here is my opinion, and shouldn't be taken as something from NASA...

Of course... Steve?

And Darrel, what about a little something on the GMAT page at Thinking Systems? (note it's way too soon to talk about this, it's just curiosity...) Could be possible?

BTW, (I'm really curious indeed) the Earth on the top frame of Thinking Systems site is from Celestia, no?

[djcinsb]

Not a problem at all on the Thinking Systems site. That one I control.

I don't remember where I got the Earth in the Thinking Systems banner -- that image was made 4 or 5 years ago, IIRC. I remember spending hours in the GIMP trying to get something I liked...

The Earth image very well may have come from Celestia. I remember looking for a nice image in several different places, including Celestia. Is there any way to verify that it came from Celestia? If so, I'll add a footnote to that effect the next time I update the web pages.

[t00fri]

I'm asking because actually Celestia dev is not in good shape,

Hey, hey...old friend,

as a longstanding Celestia dev & co-author I definitely disagree:

we are in perfect shape but just lurking around;-). Development is
effectively blocked, since our lead programmer (Chris Laurel) is once
more "hiding" since > 2 months. Last time he wrote a post in this
forum was on July 10th, despite his claim that he now works full time
on Celestia (starting July 1st). About a week ago there was a brief
reappearance of Chris in the dev-list....But since then he's not been
seen ...No one seems to know, when he definitely plans to reappear.


Bye Fridger

[ElChristou]

Not a problem at all on the Thinking Systems site. That one I control.

Cool!

...If so, I'll add a footnote to that effect the next time I update the web pages.

No, as the image got some tweaking it's not a problem, was just (really!) curiosity...

[ElChristou]

I'm asking because actually Celestia dev is not in good shape,

Hey, hey...old friend,

as a longstanding Celestia dev & co-author I definitely disagree:

we are in perfect shape and just lurking around;-)
...

Which do you prefer? this one: or that one:

[t00fri]

we are in perfect shape and just lurking around;-)
...

Which do you prefer? this one: or that one:


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J'm'en foute carrement...Je m'en fiche,
J'm'en collise bien... et Je, m'en, crise.

Translation to English poetry:

The petals of my once blooming flower,
lament and wither without your love's shower.


ahem...

[Cham]

J'm'en foute carrement...Je m'en fiche,
J'm'en collise bien... et Je, m'en, crise.
.

LOL, this is from Quebec !

or again :

J'm'en tabarnak-tu !? Je m'en consaint-ciboirise ! Et je m'en sacre.

[t00fri]

J'm'en tabarnak-tu !? Je m'en consaint-ciboirise ! Et je m'en sacre.

hi hi, this is INSANE ! But indeed I personally know a
number of French-Canadiens. Speaking French with them is
kind of a challenge

Bye Fridger

[ElChristou]

Really I think I do prefer the English version...

[ElChristou]

Ah, friends form the GMAT dev, if you really want a collaboration, better mailing directly to Chris L. for any consultation because seems that actually you won't have much chance to get his opinion here on the forum...

(Now you are welcome to post any advancement of this collaboration, because we (poor users ) are still interested in Chris decisions... )

[steven hughes]

Steve,

For those who aren't on the best of terms with celestial mechanics , programs like this can be intimidating. What's the chance of the documentation including a "worked example"? e.g. takeoff from Earth through landing on Mars?

I'd be glad to put something together like this. In fact, I hope to start a Wiki that contains tutorials and more documentation on how to use GMAT. For starters, GMAT does not currently model launches. It will assume you start from a parking orbit.

For starters, what if I write a detailed tutorial on how to design a mission that starts from a low Earth orbit, and goes to the Moon? Then I can work on mars next.... I can have this ready in a week or so I think... I'll have to put this together in my free time.

I"ll assume the user is building a mission from scratch.

[selden]

Steve,

All of those ideas sound great!

[t00fri]

It would be useful to hear what kind of interface the GMAT people would like to see in Celestia.

It is obvious that Celestia should strive for a healthy balance as to its interfaces to all sorts of external tools. SPICE was done. Now GMAT...what will be next? Apparently the SPICE and GMAT people don't communicate too much with each other?

Personally, I am not too happy about this sort of approach. Also there was still no explanation what "ordinary people" are from a NASA perspective?

by working inclusively with ordinary people, universities, businesses, and other government organizations

Like others I really would like to hear more explicitly what would be the benefits for the Celestia project as a whole, if we collaborate?

Clearly NASA or ESA might one day offer some paid contracting work for the Celestia project leader (Chris L.) for example. This happened before. The natural implication of course would be that the other developers follow for FREE...AHA. That's life.

What else? What would be the compromises as to Celestia that one might hope to see from "the other side"? Would there be some menpower ready to actively promote also the development of Celestia, for example? This I doubt in case of the commercial contractors

Honestly, for me statements like "this might help to make Celestia better known" are way too vague, notably since they don't cost a cent

Did I forget anything significant?

Bye Fridger

[ElChristou]

For starters, what if I write a detailed tutorial on how to design a mission that starts from a low Earth orbit, and goes to the Moon? Then I can work on mars next.... I can have this ready in a week or so I think... I'll have to put this together in my free time...

Hey Steve, we have currently a work in progress on Apollo 11 (new models), and the plan is to reconstruct the whole mission from deployment of the LEM from the S-IVB to mooning + come back and splashdown...

I'm wondering if GMAT could not be used for the trajectories and orbits... Perhaps it would be a fun way to do your tut?

(for the Apollo WIP, see: http://shatters.net/forum/viewtopic.php?t=11011)

[ElChristou]

...What else? What would be the compromises as to Celestia that one might hope to see from "the other side"? Would there be some menpower ready to actively promote also the development of Celestia, for example? This I doubt in case of the commercial contractors ...

Steve, I think you miss it, I was also wondering about the benefit of this collaboration for Celestia and I was asking you on the previous page about the possibility or not (IF this collaboration goes on, of course) to have a bit of promotion (reason of choosing Celestia, screenshots, link) for Celestia on the GMAT page @ Nasa...

Possible or unrealistic?

[steven hughes]

Hey Steve, we have currently a work in progress on Apollo 11 (new models), and the plan is to reconstruct the whole mission from deployment of the LEM from the S-IVB to mooning + come back and splashdown...

I'm wondering if GMAT could not be used for the trajectories and orbits... Perhaps it would be a fun way to do your tut?

GMAT can recreate these trajectories fairly easily (except reentry portion), assuming I can track down some of the historical data. If I can find the data on the mission I'd be glad to use the Apollo 11 trajectory for a tutorial.

One concern I have is that GMAT and Celestia may not use the same models for the locations of the Earth and Moon. If there's a significant difference in the locations of the planets in the two systems, there may be an issue in plotting the orbits... not sure though. GMAT uses JPL DE405 files for planetary ephemeris. What does Celestia use?

[steven hughes]

Steve, I think you miss it, I was also wondering about the benefit of this collaboration for Celestia and I was asking you on the previous page about the possibility or not (IF this collaboration goes on, of course) to have a bit of promotion (reason of choosing Celestia, screenshots, link) for Celestia on the GMAT page @ Nasa...

Possible or unrealistic?

I've been busy the last few days so haven't been able to spend the time I'd like to on this response.... and I'm going to shut down the computer for the evening... So, I'll reply this weekend.

[djcinsb]

Would there be some menpower ready to actively promote also the development of Celestia, for example? This I doubt in case of the commercial contractors

Well, I can't speak to most of what was asked in this original message, since I'm not a NASA employee. But as the -- currently only -- commercial contractor on GMAT, I would like to point out that I've already stated that at a minimum I'm quite willing to add a link and information about Celestia on Thinking Systems' website, assuming we do something together. Thinking Systems will do what it can along those lines -- but of course I cannot speak for any other commercial concerns. (I can't commit to monetary compensation; Thinking Systems struggles to cover its own expenses.)

In terms of the advertising side of what can happen: I believe the GMAT project intends to attribute any work performed to whoever does the work -- that is certainly the case for the work I've performed on the project, both paid and unpaid.

For an example of the latter, one component of GMAT is its XY plot widget, which was developed outside of GMAT on Thinking Systems company funds. The widget has (1) a reference on GMAT's about panel, (2) mention on the GMAT web site, and (3) for the code that is in GMAT, follows the terms of my license. So while I can't commit that NASA will continue to do what they can along these lines, they have so far done everything they could to credit work done with Thinking Systems, given US government constraints.

[ElChristou]

...GMAT uses JPL DE405 files for planetary ephemeris. What does Celestia use?

If I'm not wrong, VSOP87... (but there was some discussion about the eventual use of VSOP2000)

[selden]

One concern I have is that GMAT and Celestia may not use the same models for the locations of the Earth and Moon. If there's a significant difference in the locations of the planets in the two systems, there may be an issue in plotting the orbits... not sure though. GMAT uses JPL DE405 files for planetary ephemeris. What does Celestia use?

Celestia's standard distribution uses a truncated VSOP87 for the major planets. I don't know what it uses for the Lunar orbit. The results are close to but not identical to DE405. As an option, one can use either DE405 or DE406 with Celestia v1.5.0, although they require downloading large data files. An Addon can use whichever ephemeris is appropriate of VSOP87, JPL40x, SPICE or even just Keplerian parameters.