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Jud McCranie
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 Posted: Sun Jun 17, 2007 7:32 pm Post subject: LOR question |
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At http://oea.larc.nasa.gov/PAIS/Rendezvous.html it says "If
rendezvous had to be part of Project Apollo, critics of LOR felt that
it should be done only in Earth orbit. if that rendezvous failed, the
threatened astronauts could be brought back home simply by allowing
the orbit of their spacecraft to deteriorate. "
If the LM was allowed to reenter, the astronauts are dead anyway. Is
the point really that there is a chance of a rescue mission if the
rendezvous fails in Earth orbit?
--
Replace you know what by j to email |
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Jud McCranie
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| Posted: Sun Jun 17, 2007 7:41 pm Post subject: Re: LOR question |
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On Sun, 17 Jun 2007 11:32:26 -0400, Jud McCranie
<youknowwhat.mccranie@adelphia.net> wrote:
| Quote: |
At http://oea.larc.nasa.gov/PAIS/Rendezvous.html it says "If
rendezvous had to be part of Project Apollo, critics of LOR felt that
it should be done only in Earth orbit. if that rendezvous failed, the
threatened astronauts could be brought back home simply by allowing
the orbit of their spacecraft to deteriorate. "
If the LM was allowed to reenter, the astronauts are dead anyway. Is
the point really that there is a chance of a rescue mission if the
rendezvous fails in Earth orbit?
|
I realized that they are talking about no orbit around the moon, and
really talking about a failure of the SM engine - not a failure of the
rendezvous.
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Replace you know what by j to email |
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Henry Spencer
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| Posted: Sun Jun 17, 2007 9:52 pm Post subject: Re: LOR question |
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In article <gtka73ppt1v80jbdflpcdnkqclfusvo0su@4ax.com>,
Jud McCranie <youknowwhat.mccranie@adelphia.net> wrote:
| Quote: |
"...it should be done only in Earth orbit. if that rendezvous failed, the
threatened astronauts could be brought back home simply by allowing
the orbit of their spacecraft to deteriorate. "
If the LM was allowed to reenter, the astronauts are dead anyway.
|
With rendezvous only in Earth orbit, there is no LM. The only spacecraft
the astronauts ever occupy is the CM.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net |
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Jud McCranie
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| Posted: Mon Jun 18, 2007 5:33 am Post subject: Re: LOR question |
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On Sun, 17 Jun 2007 17:52:13 GMT, henry@spsystems.net (Henry Spencer)
wrote:
| Quote: |
With rendezvous only in Earth orbit, there is no LM. The only spacecraft
the astronauts ever occupy is the CM.
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You're right, I wasn't thinking correctly at the time. But the
website is still confusing on that issue.
--
Replace you know what by j to email |
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OM
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| Posted: Mon Jun 18, 2007 10:35 am Post subject: Re: LOR question |
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On Sun, 17 Jun 2007 11:41:58 -0400, Jud McCranie
<youknowwhat.mccranie@adelphia.net> wrote:
| Quote: |
On Sun, 17 Jun 2007 11:32:26 -0400, Jud McCranie
youknowwhat.mccranie@adelphia.net> wrote:
At http://oea.larc.nasa.gov/PAIS/Rendezvous.html it says "If
rendezvous had to be part of Project Apollo, critics of LOR felt that
it should be done only in Earth orbit. if that rendezvous failed, the
threatened astronauts could be brought back home simply by allowing
the orbit of their spacecraft to deteriorate. "
If the LM was allowed to reenter, the astronauts are dead anyway. Is
the point really that there is a chance of a rescue mission if the
rendezvous fails in Earth orbit?
I realized that they are talking about no orbit around the moon, and
really talking about a failure of the SM engine - not a failure of the
rendezvous.
|
....Ah, but the real "What The Fuck??" scenario is how the crew
would/could survive any combination of two failures following an SM
main engine *and* RCS failure:
1) What if the SM could not be detached?
....And/Or:
2) What if the LM could not be detached?
....Somehow I doubt the Glenn option would be applicable, much less
desireable.
OM
--
]=====================================[
] OMBlog - http://www.io.com/~o_m/omworld [
] Let's face it: Sometimes you *need* [
] an obnoxious opinion in your day! [
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OM
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| Posted: Mon Jun 18, 2007 10:43 am Post subject: Re: LOR question |
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On Sun, 17 Jun 2007 17:52:13 GMT, henry@spsystems.net (Henry Spencer)
wrote:
| Quote: |
With rendezvous only in Earth orbit, there is no LM.
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....Wait, this doesn't exactly make sense, Henry. If there's no LM, why
would there be any sort of OR at all?
[Possible T-Shirt Alert; Weasle-Word Deflectors ON!]
OM
--
]=====================================[
] OMBlog - http://www.io.com/~o_m/omworld [
] Let's face it: Sometimes you *need* [
] an obnoxious opinion in your day! [
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Dave Michelson
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| Posted: Mon Jun 18, 2007 12:11 pm Post subject: Re: LOR question |
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OM wrote:
| Quote: |
On Sun, 17 Jun 2007 17:52:13 GMT, henry@spsystems.net (Henry Spencer)
wrote:
With rendezvous only in Earth orbit, there is no LM.
...Wait, this doesn't exactly make sense, Henry. If there's no LM,
why would there be any sort of OR at all?
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To save weight, the CSM would be launched without its earth departure
stage or with the stage empty.
Once in orbit, the crew would have to offload the earth deprture
propellants from an unmanned tanker or, alternatively, rendezvous with
the earth departure stage.
--
Dave Michelson
davem@ece.ubc.ca |
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Neil Gerace
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| Posted: Mon Jun 18, 2007 2:24 pm Post subject: Re: LOR question |
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On Jun 18, 2:43 pm, OM <om@all_trolls_must_DIE.com> wrote:
| Quote: |
On Sun, 17 Jun 2007 17:52:13 GMT, h...@spsystems.net (Henry Spencer)
wrote:
With rendezvous only in Earth orbit, there is no LM.
...Wait, this doesn't exactly make sense, Henry. If there's no LM, why
would there be any sort of OR at all?
[Possible T-Shirt Alert; Weasle-Word Deflectors ON!]
|
The crew module would have to be transferred from the launch vehicle
to the lunar transfer stage. |
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OM
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| Posted: Mon Jun 18, 2007 6:13 pm Post subject: Re: LOR question |
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On Mon, 18 Jun 2007 03:24:33 -0700, Neil Gerace
<geracen@webace.com.au> wrote:
| Quote: |
On Jun 18, 2:43 pm, OM <om@all_trolls_must_DIE.com> wrote:
On Sun, 17 Jun 2007 17:52:13 GMT, h...@spsystems.net (Henry Spencer)
wrote:
With rendezvous only in Earth orbit, there is no LM.
...Wait, this doesn't exactly make sense, Henry. If there's no LM, why
would there be any sort of OR at all?
[Possible T-Shirt Alert; Weasle-Word Deflectors ON!]
The crew module would have to be transferred from the launch vehicle
to the lunar transfer stage.
|
....But is Henry referring to an EOR version of the DA mode? It's his
wording here that confused me significantly.
OM
--
]=====================================[
] OMBlog - http://www.io.com/~o_m/omworld [
] Let's face it: Sometimes you *need* [
] an obnoxious opinion in your day! [
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Guest
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| Posted: Mon Jun 18, 2007 9:46 pm Post subject: Re: LOR question |
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On Jun 18, 9:13 am, OM <om@all_trolls_must_DIE.com> wrote:
| Quote: |
On Mon, 18 Jun 2007 03:24:33 -0700, Neil Gerace
gera...@webace.com.au> wrote:
On Jun 18, 2:43 pm, OM <om@all_trolls_must_DIE.com> wrote:
On Sun, 17 Jun 2007 17:52:13 GMT, h...@spsystems.net (Henry Spencer)
wrote:
With rendezvous only in Earth orbit, there is no LM.
...Wait, this doesn't exactly make sense, Henry. If there's no LM, why
would there be any sort of OR at all?
[Possible T-Shirt Alert; Weasle-Word Deflectors ON!]
The crew module would have to be transferred from the launch vehicle
to the lunar transfer stage.
...But is Henry referring to an EOR version of the DA mode? It's his
wording here that confused me significantly.
|
I know Henry will answer, but I'll just kick in my 2 cents anyway
because I have the time.
Originally, when we had no rendezvous experience, there was no
consideration that two spacecraft would be able to dock in lunar
orbit. Therefore, the plan was to design a CM / SM combination that
would leave the earth, land, take off, and come directly back. This
is why the SM was oversized compared to the actual need.
This left the question of how to get the CSM out of earth orbit. You
had two choices. First, build one honking big launcher and send the
whole thing directly to the moon (direct ascent). The other was to
use two smaller launchers, one to lift the CSM into orbit and the
other to lift the lunar injection stage. The CSM would use the lunar
injection stage to get out of earth orbit (the earth orbit rendezvous
option). Neither considered an LM, based on the original assumption
that LOR was not feasible. |
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OM
Guest
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| Posted: Mon Jun 18, 2007 11:46 pm Post subject: Re: LOR question |
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On Mon, 18 Jun 2007 10:46:08 -0700, jbeadles@pobox.com wrote:
| Quote: |
...But is Henry referring to an EOR version of the DA mode? It's his
wording here that confused me significantly.
I know Henry will answer, but I'll just kick in my 2 cents anyway
because I have the time.
|
<SNIP>
....Nonono, I *know* all this. I'm very well versed in the modes that
were discussed. It's just that Henry's wording, for some reason, threw
me off as if he were discussing another EOR mode.
Jeez, you get tied up with work/travel, get behind in keeping the
group agitated properly, and everyone treats you like a goddamn
n00b...:p
OM
--
]=====================================[
] OMBlog - http://www.io.com/~o_m/omworld [
] Let's face it: Sometimes you *need* [
] an obnoxious opinion in your day! [
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robert casey
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| Posted: Tue Jun 19, 2007 2:12 am Post subject: Re: LOR question |
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| Quote: |
Originally, when we had no rendezvous experience, there was no
consideration that two spacecraft would be able to dock in lunar
orbit.
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That task looks pretty hard, considering you have a pair of objects
about 10 meters wide trying to find each other after being apart a
distance of 5 or more Megameters (5000km). Well, not that bad, but you
could get within say 100km. Radar, beacons and enough control of
thrusters takes care of the rest, but you'd want to get some experience
(like the two at the same time Gemini missions) with a pair of manned
spacecraft that can each reenter safely if things don't work out. You
can try out the radar and beacons with airplanes first, but that's
mostly 2 dimensions with a little bit of vertical dimension thrown in.
The Air Force routinely does that for in flight refueling, so we know
that that can be done. But doing it in an atmosphere vs in orbit is
somewhat different. But you want to try it before sending someone off
in a spacecraft that can't return by itself in case it doesn't work.
But once you have a handle on that, doing LOR means you don't need to go
down the Moon's gravity well with the fuel and equipment you need for
Earth return. And of course once you've landed with the LM and come
back for LOR, you then toss the LM and save the fuel you would have
needed to get the LM's mass out of lunar orbit and back to Earth.
Of course this is all well known history now... |
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Henry Spencer
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| Posted: Tue Jun 19, 2007 7:09 am Post subject: Re: LOR question |
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In article <qaac73tdj3onnq1npnl5hogbumae5lt9qg@4ax.com>,
OM <om@all_trolls_must_DIE.com> wrote:
| Quote: |
With rendezvous only in Earth orbit, there is no LM.
...Wait, this doesn't exactly make sense, Henry. If there's no LM, why
would there be any sort of OR at all?
|
As others have already noted: without a separate LM, you couldn't launch
the whole thing on one rocket, so you'd have to rendezvous in LEO with
either the departure stage, or a tanker to fill the empty departure stage.
Actually it goes a little deeper than that, because at the time LOR was
first proposed, you would probably have needed *several* launches, not
just two, for an EOR scheme... and LOR would also have needed more than
one, although not as many.
Looking only at the final results, it's easy to overlook just how rapidly
the rockets grew. The "improved Saturn" that would be used to launch
either EOR or LOR started out not too much bigger than a Saturn IB, and
visibly derived from the Saturn I. Only two or three years later, it was
bigger than most of the original Nova concepts, and all it had in common
with the Saturn I was the name.
In summer 1961, if you had told Max Faget's spacecraft designers just how
*immense* von Braun's rocket would end up being -- and somehow made them
believe you! -- probably they would have discarded *all* the rendezvous-
based schemes as obviously unnecessary. (Which might have made things a
bit sticky after three or four years of spacecraft weight growth...)
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net |
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Henry Spencer
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| Posted: Tue Jun 19, 2007 8:10 am Post subject: Re: LOR question |
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In article <CrDdi.2604$ZY1.2173@newsread2.news.pas.earthlink.net>,
robert casey <wa2ise@ix.netcom.com> wrote:
| Quote: |
But once you have a handle on that, doing LOR means you don't need to go
down the Moon's gravity well with the fuel and equipment you need for
Earth return. And of course once you've landed with the LM and come
back for LOR, you then toss the LM and save the fuel you would have
needed to get the LM's mass out of lunar orbit and back to Earth.
|
Interestingly enough, though, what you end up with is a system optimized
for relatively brief visits. The more you start thinking about long stays
with larger crews and plenty of surface equipment -- the more your system
stops being a small lander as an auxiliary to a main spacecraft, and
becomes a heavy lander plus a small return vehicle -- the less favorable
LOR looks. Especially if the return vehicle has to regularly burn fuel to
keep its orbit passing over the landing site, to retain the option of
emergency departure on short notice. Eventually, taking a lightweight
return vehicle down to the surface with you starts to look better.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net |
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Dave Michelson
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| Posted: Tue Jun 19, 2007 12:36 pm Post subject: Re: LOR question |
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Henry Spencer wrote:
| Quote: |
In summer 1961, if you had told Max Faget's spacecraft designers just how
*immense* von Braun's rocket would end up being -- and somehow made them
believe you! -- probably they would have discarded *all* the rendezvous-
based schemes as obviously unnecessary. (Which might have made things a
bit sticky after three or four years of spacecraft weight growth...)
|
In real life, Faget apparently enjoyed pointing out that the total
weight of the CSM and LM that flew was very close to their original
estimates for the Direct Ascent craft. (M&C, p. 117)
However, the Heaton committee was advocating the C-4 for EOR in Summer
1961 and it wasn't /that/ much smaller than the Saturn V. The really
big jump was from C-2 and C-3 (1960) to the C-4 and C-5 (1961).
--
Dave Michelson
davem@ece.ubc.ca |
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