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OFMM Discussions for the OFMM project.

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Old 12-31-2011, 10:03 PM   #61
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Quote:
Originally Posted by Arrowstar View Post
 Put the comm sats into a nice, highly elliptical orbit with their engines, lower apoapse the (hopefully small) required amount, and raise periapse out of atmosphere.
MRO did it the other way around. Capture into a elliptical orbit, and then lower the periapsis to circularize orbit over a longer period.

But you'll still need enough DV in your budget to get into the elliptical orbit. If you plan to skim the atmosphere during insertion, you
WILL need a heat shield.

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Old 12-31-2011, 10:34 PM   #62
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I had said, for 30 days to get out of Earth orbit. I am getting this from a 1999 Scientific American article, that detailed it's specifics, approach, and et cetera. Do you guys want me to post the specifics.
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Old 12-31-2011, 10:35 PM   #63
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Nope because we aren't using anything like that.
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Old 12-31-2011, 11:14 PM   #64
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Alright, so for the vessel(s) we are using, what kind of transfer are we planning?
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Old 01-01-2012, 02:22 AM   #65
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That has all been worked out (see the previous four pages of this thread). I will be publishing a technical memo in the next few days that describes precisely that. Please be patient with me, it's a busy time of year and I can only get so much done per day.
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Old 01-01-2012, 02:23 AM   #66
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Originally Posted by Lord Wasteland View Post
 Alright, so for the vessel(s) we are using, what kind of transfer are we planning?
Read the mission discussion thread and the missions list. This has all been worked out and major changes to the missions are no longer being accepted.

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 That has all been worked out (see the previous four pages of this thread). I will be publishing a technical memo in the next few days that describes precisely that. Please be patient with me, it's a busy time of year and I can only get so much done per day.
Take your time, we have a little bit of time prior to mars missions. I appreciate all your hard work arrowstar.
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Old 01-01-2012, 07:29 AM   #67
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Alright, I need some help from someone who's good with TransX or IMFD. Please do the following:

-Place a DG in a 200x200 Earth orbit with 0 inclination.
-Set the date to 18 July 2018 at 12:00:00.
-Using TransX or IMFD, find a trajectory that gets to Mars on 12 October 2018
-Report back letting me know what the departure dV is

Thanks!
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Old 01-01-2012, 07:56 AM   #68
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Quote:
Originally Posted by Arrowstar View Post
 Alright, I need some help from someone who's good with TransX or IMFD. Please do the following:

-Place a DG in a 200x200 Earth orbit with 0 inclination.
-Set the date to 18 July 2018 at 12:00:00.
-Using TransX or IMFD, find a trajectory that gets to Mars on 12 October 2018
-Report back letting me know what the departure dV is

Thanks!
Hi Arrowstar, happy New Year!

The following results are with IMFD.

Departure: 18 July 2018 - Arrival 12 October 2018 - Time of flight: 86 days

dV 7229 m/s for Inc 0 degrees (ecliptic) 23,4393 degrees (equatorial).

dV 7148 m/s for Inc 27,93 degrees (eq) with a LAN at 7,68 degrees.

dv 8860 m/s for Inc 0 degrees (eq).

Hope these help
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Old 01-01-2012, 04:01 PM   #69
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Originally Posted by dgatsoulis View Post
 Hi Arrowstar, happy New Year!

The following results are with IMFD.

Departure: 18 July 2018 - Arrival 12 October 2018 - Time of flight: 86 days

dV 7229 m/s for Inc 0 degrees (ecliptic) 23,4393 degrees (equatorial).

dV 7148 m/s for Inc 27,93 degrees (eq) with a LAN at 7,68 degrees.

dv 8860 m/s for Inc 0 degrees (eq).

Hope these help
7229 m/s ?

Sounds a bit high.
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Old 01-01-2012, 04:04 PM   #70
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 7229 m/s ?

Sounds a bit high.
Because you get to Mars in 86 days!
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Old 01-02-2012, 12:47 AM   #71
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Yeah, I was expecting high dV. I think I have an error in my departure tool somewhere, I just need to find it.

Thanks, dgatsoulis!

---------- Post added at 07:47 PM ---------- Previous post was at 11:12 AM ----------

Hi everyone:

I've put online a draft memo that outlines the departure and arrival dates of each Mars mission, the trajectories of each mission, and other considerations. Can I get extra sets of eyes on this document? Comments and constructive criticisms are most welcome. In particular, there are action items listed at the end of the memo that I'd like others to think about. Also, items listed in yellow are those items I was just guessing at.

Get the memo here.

Thanks!

Last edited by Arrowstar; 01-01-2012 at 04:37 PM.
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Old 01-02-2012, 02:28 AM   #72
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Just went through the memo, excellent job Arrowstar.
Everything seems fine and I agree with you, we need to discuss the OFMM 20 departure date, because with the current plan, it will get to Mars 4 months after the human mission.

One thing I don't understand is why "the DSCS vehicles have 2017 km/s of ΔV available."
With an emptymass of 780kg , fuel 1497,54kg and an exhaust velocity of 3092 m/s , the available dv is 3313,25 m/s. Am I missing something here?
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Old 01-02-2012, 02:32 AM   #73
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 One thing I don't understand is why "the DSCS vehicles have 2017 km/s of ΔV available."
It was from the add-on's description.
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Old 01-02-2012, 02:38 AM   #74
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Originally Posted by Pipcard View Post
 It was from the add-on's description.
Thanks, I hadn't noticed it. Still 2017 m/s of dv is not right. Even in the scenario provided with the DSCS, on which the tanks are half full, the dv is 2081 m/s.
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Old 01-02-2012, 02:58 AM   #75
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So how much dV do we have? 3313 m/s?

Any suggestions on how to deal with the fuel ship departure/arrival dates?
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