Moon shot from KSC Launch Window

[Clavius0712]

Hi all,

Does anyone know how to figure out future launch window dates for "KSC to Moon" trips? I read somewhere that KSC is lined up perfectly for a Moon shot every 28 days, but I don't know how to figure out which days these are.

Any help would be much appreciated.

 

[RisingFury]

You can launch every day.

In Align Planes MFD set Moon as your target. When angle gets to it's lowest and the change of angle over time is at 0, it's time to launch. Launch due east and correct as you go.

 

[Clavius0712]

You can launch every day.

In Align Planes MFD set Moon as your target. When angle gets to it's lowest and the change of angle over time is at 0, it's time to launch. Launch due east and correct as you go.

True, but then why did NASA have specific launch windows for the Apollo missions, and why were they always on a launch azimuth of about 72 degrees rather than 90?

 

[agentgonzo]

True, but then why did NASA have specific launch windows for the Apollo missions, and why were they always on a launch azimuth of about 72 degrees rather than 90?

Nasa had a lot more constrainsts than we do in orbiter. For example, they needed the landing site to be in sunlight when they landed, which ruled out half of the month. There are probably more like that.

As for the launch heading, I'm not sure, but I think that one of the factors is that the TLI burn that they did set them up on a free-return trajectory that not only got them coming back to the Earth, but also back to the landing site in the Pacific (or was it Atlantic?) in case anything went wrong.

 

[MAraujo]

For example, they needed the landing site to be in sunlight when they landed, which ruled out half of the month.

Not only in sunlight but near the terminator. The design of the LEM and the Astronaut's suits depended on a rather low angle of insulation to keep things from overheating. Not to mention, while in flight, its a lot easier to identify surface features with longer shadows.

 

[pattersoncr]

See this page from the Apollo Flight Journal for an extensive discussion of how the Apollo launch windows were developed:

Apollo Launch Windows

 

[Clavius0712]

See this page from the Apollo Flight Journal for an extensive discussion of how the Apollo launch windows were developed:

Apollo Launch Windows

Wow, that article was really interesting. It's amazing how many factors were considered when planning an Apollo launch. Those guys with their slide-rules back in '69 sure were smart!

To summarise the above then, the launch window was designed to ensure that a) the lunar landing would have the correct lighting conditions; b) the craft only had to do a couple of orbits before initiating the TLI burn to avoid fuel "boil-off"; c) the craft could be tracked along its entire orbit by various ships at sea, and d) the craft would be placed into a free-return re-entry trajectory in case of problems.

Thanks for a really informative online resource.

 

[pattersoncr]

Glad you enjoyed it. AFJ is quite the gem!

 

[ijuin]

A point to take note of is that with the new Constellation hardware, improved insulation, etc. will mean that it will be possible to remain on the lunar surface throughout most of the lunar day instead of having to leave before temperatures peak. Also, the Earth Departure Stage will have an on-orbit duration of days instead of hours,

 

[the.punk]

When you don't want your landing side specificly in day you can launch every day.
And for this with the 90°..it's because it is the most fuel efficient because you use the rotation of earth.

 

[agentgonzo]

Glad you enjoyed it. AFJ is quite the gem!

I'll second the praise for the link. That was a wonderful read. Fully of technical details, yet in simple english so that it's plainly understandable. A fantastic read and incredibly enlightening! Thank you again!