Request General Launch Windows 20 Years

[Zachstar]

I figure some here are skilled at configuring various tools for determining these windows. However, I generally suck at them and have had a bit of an issue finding windows for various types of transfers.

So if you masters of deep space navigation do not mind. I would like to request any good windows you happen to have or can quickly generate.

+- 20 Years

Mars
Venus
Outer Planets (Anything interesting)
Free Return from any of above.
Any windows allowing Multiple Earth and lunar passes before outward to a planet.

Just need launch,arrival,Vel change, And any notes you care to add. I want to do the rest with TransX if I can ever get used to the thing for slingshots.

Thanks!

 

[Dude]

OK, I'm not sure what you're asking for here. By launch windows, do you mean, for example ...

1) "I need to know when Jupiter is in a good position relative to Earth that I can send a craft to it in a way I need" -- whether that's minimal delta-V for the eject from Earth orbit; or maybe Jupiter is in a good position to be used for a sling to Saturn; etc. Or,

2) "I already have the answer to #1. I need to know exactly when to take off from where I'm parked on Earth, what launch heading to use, etc., to get into a good orbital plane for the eject burn."

If you're asking for #1, I can't help you. Ignore the rest of this post -- or read on, if you're interested.

If you're asking for #2, I'm developing code for that. Right now, I've got it done for takeoffs only from Earth to other planets, but as far as I can tell I've got that part working fine. Now I just need to generalize it for takeoffs from other bodies; Earth-to-Moon trips; etc.

For example, there's a good Hohmann opportunity from Earth to Jupiter coming up about two months from now. From looking at Transfer MFD, ejecting from Earth orbit at MJD 56153.5865 for arrival at Jupiter at MJD 57031.6606 works, so let's use that. If you give me this data ...

1) Where you want to go from Earth -- in this case, Jupiter.
2) When you plan to do your eject burn from Earth -- in this case, MJD 56153.5865
3) When you'd like to arrive at your destination -- in this case, MJD 57031.6606
4) Where you're going to launch from -- in this case, let's say Cape Canaveral

I can give you launch windows to get into a good eject plane:

Launch_MJD Launch_heading ECL_Inc ECL_LAN
56149.3043 57.2 31.4 282.3
56150.3015 57.2 31.4 282.3
56151.2988 57.2 31.4 282.3
56152.2961 57.2 31.4 282.3
56153.2933 57.2 31.4 282.3

56148.6030 122.8 31.4 282.3
56149.6003 122.8 31.4 282.3
56150.5975 122.8 31.4 282.3
56151.5948 122.8 31.4 282.3
56152.5921 122.8 31.4 282.3

... where "Launch MJD" and "Launch heading" should be obvious; "ECL Inc" and "ECL LAN" indicate the plane of the parking orbit you're launching into.

The criteria I'm using is, what are the times when you can use a launch heading as close to 90 degrees as possible, to take maximum advantage of inherited velocity from Earth's rotation. Sometimes there are times when a 90 degree heading is possible, sometimes there aren't. Sometimes there are two different orbital planes available, sometimes there's only one.

Furthermore, assuming the Earth orbit you're going to eject from is circular, then if you give me:

5) The ECL Inc and LAN of the parking orbit you're going to eject from -- in this case, 31.4, 282.3 (from the above data); and
6) The radius of your parking orbit -- for this example, let's use 6580 km

I can give you this additional information:

Eject burn delta-vee = 6911.21 m/s
Location of eject burn (TrL in ECL frame) = 294.55
Predicted ECL frame Earth orbit elements just after burn
SMa = -4206000 m
Ecc = 2.564
Inc = 31.4
LAN = 282.3
LPe = 294.55

Anyway, if that sort of information would help you out, let me know.

 

[kamaz]

Here is an Excel sheet for calculating approximate Hohmannn transfers within the Solar System: http://clowder.net/hop/railroad/Hohmann.xls

In addition to ejection and arrival dates, it also gives you the delta-v required for ejection and braking.

It is an approximation, because it assumes that orbits are circular and coplanar. I'd use that as a starting point and then use transX to plot the exact trajectory.

 

[Zachstar]

Thank you for that. I was mainly asking for general windows. I was expecting results as far as say months or parts of years.

When I said "good" I should have said interesting. Venus swings, Free returns. Stuff that we would use if we had limited Dv but unlimited probes. (Wasnt the probe of choice the chapman a while back?)

Mindblast was working on an addon called "Orbiter Navigator" some time back. I had hoped that if it could use the data spat out by "Trajectory Optimization tool" I could come up with a near infinite amount of interesting mission plans, Have any kind of burn time and type anywhere along the flight path and basically do anything that looked interesting. I hope that one day that addon can do that.

It was very kind of you to calculate out that Jupiter mission tho. I will fly it.

Let me try to narrow my request. Does anyone happen to have any TransX saves or general windows for anything involving maybe a couple of venus swings or a venus-earth swing? Maybe a Venus, Earth, Mars swing? (I know that last one is particularly a bit much to request as any kind of free return is rare to start)

 

[BruceJohnJennerLawso]

There are also some premade launch window tables on the site kamaz linked to

http://clowder.net/hop/railroad/sched.html

I just opened them and saved them as HTML, very useful

 

[kamaz]

What about this? [ame="http://www.orbithangar.com/searchid.php?ID=5418"]Trajectory Optimization Tool v2.1[/ame]

The Trajectory Optimization Tool is a MATLAB-based utility used for finding the optimal trajectory between any number of bodies in the solar system. Given an initial planet, the subsequent bodies to visit, and a range of dates for launch and arrival, this tool will provide the user with the optimal flight plan for accomplishing the mission's goals. It is a perfect complement to TransX or similar Orbiter MFDs in that it can provide launch and arrival dates, deltaV estimates, and other necessary figures needed to execute an interplanetary mission.

The internals of the software use a Gooding solver in order to solve Lambert's problem. A patched conics approximation is used when computing flyby manuevers. Ephemerides provided are from JPL's Navigation and Ancillary Information Facility.

We even have a thread about it: http://www.orbiter-forum.com/showthread.php?t=24053#post294564

Also, there existed a free program called JAQAR Swingby Calculator, which would allow you to calculate a trajectory with fly-bys. I say existed, because there are some websites referencing it, but the download is nowhere to be found. Here is a misssion designed with it: http://ccar.colorado.edu/asen5519/imd/final/Peter/Project 2 web.htm