SLA question

[Alan Erskine[_2_]]

During all the Lunar Apollo missions, the panels of the SLA (Spacecraft
Lunar module Adaptor) were jettisoned from the S-IVb during the T&D
(Transposition and Docking); but, as the panels were travelling along the
same trajectory as the rest of the spacecraft, did any of the panels crash
into the moon?

[Scott Stevenson]

On Wed, 13 Aug 2008 17:37:52 GMT, "Alan Erskine"
> wrote:

>During all the Lunar Apollo missions, the panels of the SLA (Spacecraft
>Lunar module Adaptor) were jettisoned from the S-IVb during the T&D
>(Transposition and Docking); but, as the panels were travelling along the
>same trajectory as the rest of the spacecraft, did any of the panels crash
>into the moon?

That's an interesting question. I don't know, but I would guess
not. On most (all?) of the missions, the S-IVb required a maneuver
(usually, I think, a propellant dump) to put it on a collision course.

When the panels were released, they had some "lateral" motion to them.
If that was only 1 fps, they would be about 45 miles from the original
trajectory 65 hours later, about when the spacecraft was getting ready
to go into orbit. I don't think that was a big enough difference to
put them on a collision course...

take care,
Scott

[Pat Flannery]

Scott Stevenson wrote:
>
> When the panels were released, they had some "lateral" motion to them.
> If that was only 1 fps, they would be about 45 miles from the original
> trajectory 65 hours later, about when the spacecraft was getting ready
> to go into orbit. I don't think that was a big enough difference to
> put them on a collision course...

And of course the Apollo CSM/LM wasn't sent on a collision course with
the Moon, but rather one to brake itself into orbit around the Moon.
Still that means that some of the SLA panels should be in solar orbit,
like at least one of the S-IVB's ended up.

Pat

[Alan Erskine[_2_]]

"Scott Stevenson" > wrote in message
...
> That's an interesting question. I don't know, but I would guess
> not. On most (all?) of the missions, the S-IVb required a maneuver
> (usually, I think, a propellant dump) to put it on a collision course.
>
> When the panels were released, they had some "lateral" motion to them.
> If that was only 1 fps, they would be about 45 miles from the original
> trajectory 65 hours later, about when the spacecraft was getting ready
> to go into orbit. I don't think that was a big enough difference to
> put them on a collision course...
>
> take care,
> Scott
>

I was curious about that. Thanks for the info.

[Alan Erskine[_2_]]

"Pat Flannery" > wrote in message
dakotatelephone...
>
>
> Scott Stevenson wrote:
>>
>> When the panels were released, they had some "lateral" motion to them.
>> If that was only 1 fps, they would be about 45 miles from the original
>> trajectory 65 hours later, about when the spacecraft was getting ready
>> to go into orbit. I don't think that was a big enough difference to
>> put them on a collision course...
>
> And of course the Apollo CSM/LM wasn't sent on a collision course with the
> Moon, but rather one to brake itself into orbit around the Moon.
> Still that means that some of the SLA panels should be in solar orbit,
> like at least one of the S-IVB's ended up.

I wonder if the panel's trajectories were plotted for safety reasons....

[Greg D. Moore \(Strider\)]

"Alan Erskine" > wrote in message
...
> "Scott Stevenson" > wrote in message
> ...
>> That's an interesting question. I don't know, but I would guess
>> not. On most (all?) of the missions, the S-IVb required a maneuver
>> (usually, I think, a propellant dump) to put it on a collision course.
>>
>> When the panels were released, they had some "lateral" motion to them.
>> If that was only 1 fps, they would be about 45 miles from the original
>> trajectory 65 hours later, about when the spacecraft was getting ready
>> to go into orbit. I don't think that was a big enough difference to
>> put them on a collision course...
>>
>> take care,
>> Scott
>>
>
> I was curious about that. Thanks for the info.

Wasn't one panel observed by Apollo 12 later in the flight?


>



--
Greg Moore
SQL Server DBA Consulting Remote and Onsite available!
Email: sql (at) greenms.com http://www.greenms.com/sqlserver.html

[Alan Erskine[_2_]]

"Greg D. Moore (Strider)" > wrote in message
m...
> Wasn't one panel observed by Apollo 12 later in the flight?

That's one of the things I'm wondering about, but I was more interested in
the safety aspect.

However, could the panels (and the S-IVb for that matter) make stellar
observation more difficult? However, the panels would have been tumbling,
so their albido would have varied quite a bit - that would be noticed and
quite distinctive.

[Pat Flannery]

Alan Erskine wrote:
> I wonder if the panel's trajectories were plotted for safety reasons....


They did have one "UFO" sighting from the Apollo 11 CM that was thought
to be a SLA panel that was floating fairly close to them (by space
standards, its size would make it visable from over a hundred miles
away). Buzz Aldrin said he thought it had a "L" shape when examined
through binoculars IIRC.
I should have remembered this...because of that incident, later Apollo
flights hinged the SLA panels outwards, but left them attached to the
S-IVB, so they only had to worry about one object in regards to a
accidental collision, rather than five.
That was one of the minor slips in the "Apollo 13" movie, where they
show the panels floating free of the S-IVB.
I seem to remember video taken by a earth-based telescope at the time of
Apollo 11 that showed the CSM/LM stack, S-IVB, and the four SLA panels
as they traveled through space toward the Moon; the SLA panels were
flashing as they tumbled end-over-end in the sunlight.

Pat

[Pat Flannery]

Greg D. Moore (Strider) wrote:
>> I was curious about that. Thanks for the info.
>>
>
> Wasn't one panel observed by Apollo 12 later in the flight?
>

Here's some photos of Apollos and SLAs taken from observatories:
http://www.astr.ua.edu/keel/space/apollo.html
Now, on these ones it shows that Apollo 13 _did_ jettison its SLA panels.

Pat

[Anthony Frost]

In message atelephone>
Pat Flannery > wrote:

> Greg D. Moore (Strider) wrote:
> >> I was curious about that. Thanks for the info.
> >
> > Wasn't one panel observed by Apollo 12 later in the flight?
> >
>
> Here's some photos of Apollos and SLAs taken from observatories:
> http://www.astr.ua.edu/keel/space/apollo.html
> Now, on these ones it shows that Apollo 13 _did_ jettison its SLA panels.

I did think it had been the other way round. Originally they were going
to be hinged, but on one of the early flights (without LM) a panel stuck
halfway so after that they were jettisoned. They went back to hinged for
the Skylab flights.

Anthony

[Alan Erskine[_2_]]

"Anthony Frost" > wrote in message
...
> In message atelephone>
> Pat Flannery > wrote:
>
> > Greg D. Moore (Strider) wrote:
> > >> I was curious about that. Thanks for the info.
> > >
> > > Wasn't one panel observed by Apollo 12 later in the flight?
> > >
> >
> > Here's some photos of Apollos and SLAs taken from observatories:
> > http://www.astr.ua.edu/keel/space/apollo.html
> > Now, on these ones it shows that Apollo 13 _did_ jettison its SLA
> > panels.
>
> I did think it had been the other way round. Originally they were going
> to be hinged, but on one of the early flights (without LM) a panel stuck
> halfway so after that they were jettisoned. They went back to hinged for
> the Skylab flights.
>
> Anthony

Apollo 7 had the hinged panels; then went onto explosive-bolt jettisonned
pannels because of the risk found in approaching the S-IVb stage (needed on
the Lunar flights as this is where the LM was stowed). I guess, from what
Anthony's suggesting, is that the S-IVb's for the Saturn Ib was not modified
for panel jettison.

[Rick Jones]

Alan Erskine > wrote:
> However, could the panels (and the S-IVb for that matter) make
> stellar observation more difficult? However, the panels would have
> been tumbling, so their albido would have varied quite a bit - that
> would be noticed and quite distinctive.

I think that some of the writeups in Wikipedia (yes yes...) mention
that years later what someone thought might be a new asteroid (?)
turned-out to probably be a wayward Apollo stage.

rick jones
--
a wide gulf separates "what if" from "if only"
these opinions are mine, all mine; HP might not want them anyway... :)
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

[otakenjinospam@gmail.com]

On Aug 13, 1:37*pm, "Alan Erskine" > wrote:
> During all the Lunar Apollo missions, the panels of the SLA (Spacecraft
> Lunar module Adaptor) were jettisoned from the S-IVb during the T&D
> (Transposition and Docking); but, as the panels were travelling along the
> same trajectory as the rest of the spacecraft, did any of the panels crash
> into the moon?

My calculations show that a total of 36 SLA panels were jettisoned
between Apollo 8 in 1968 and Apollo 17 in 1972.
SInce the panels were jettisoned after TLI, my guess is that they went
into solar orbit. The initial TLI burn of the S-IVB stage with the
Apollo spacecraft attached
had enough velocity to escape the Earth's gravity well, but not the
Sun's.
I doubt if they were ever tracked.

[Rick Jones]

Scott Stevenson > wrote:
> On Wed, 13 Aug 2008 17:37:52 GMT, "Alan Erskine"
> > wrote:

> >During all the Lunar Apollo missions, the panels of the SLA
> >(Spacecraft Lunar module Adaptor) were jettisoned from the S-IVb
> >during the T&D (Transposition and Docking); but, as the panels were
> >travelling along the same trajectory as the rest of the spacecraft,
> >did any of the panels crash into the moon?

> That's an interesting question. I don't know, but I would guess
> not. On most (all?) of the missions, the S-IVb required a maneuver
> (usually, I think, a propellant dump) to put it on a collision course.

> When the panels were released, they had some "lateral" motion to
> them. If that was only 1 fps, they would be about 45 miles from the
> original trajectory 65 hours later, about when the spacecraft was
> getting ready to go into orbit.

That would be a "ring" (if four? panels constitutes a ring) round the
path of the spacecraft right?

> I don't think that was a big enough difference to put them on a
> collision course...

How high was lunar orbit? I found one reference that suggested 60
miles. So if it was a bit more than 1fps there would be a chance? Or
was the LOI burn such that had it not happened, the spacecraft would
have been more than 60 miles altitude as it passed the moon?

rick jones
--
Wisdom Teeth are impacted, people are affected by the effects of events.
these opinions are mine, all mine; HP might not want them anyway... :)
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

[Scott Stevenson]

On Thu, 14 Aug 2008 21:18:19 +0000 (UTC), Rick Jones
> wrote:

>Scott Stevenson > wrote:
>> On Wed, 13 Aug 2008 17:37:52 GMT, "Alan Erskine"
>> > wrote:
>
>> >During all the Lunar Apollo missions, the panels of the SLA
>> >(Spacecraft Lunar module Adaptor) were jettisoned from the S-IVb
>> >during the T&D (Transposition and Docking); but, as the panels were
>> >travelling along the same trajectory as the rest of the spacecraft,
>> >did any of the panels crash into the moon?
>
>> That's an interesting question. I don't know, but I would guess
>> not. On most (all?) of the missions, the S-IVb required a maneuver
>> (usually, I think, a propellant dump) to put it on a collision course.
>
>> When the panels were released, they had some "lateral" motion to
>> them. If that was only 1 fps, they would be about 45 miles from the
>> original trajectory 65 hours later, about when the spacecraft was
>> getting ready to go into orbit.
>
>That would be a "ring" (if four? panels constitutes a ring) round the
>path of the spacecraft right?

Right. Each of the four panels took up 90 degrees of the
circumference. Assuming they all separated with equal energy exactly
perpendicular to the path of the spacecraft, you should get a steadily
expanding ring.
>
>> I don't think that was a big enough difference to put them on a
>> collision course...
>
>How high was lunar orbit? I found one reference that suggested 60
>miles. So if it was a bit more than 1fps there would be a chance? Or
>was the LOI burn such that had it not happened, the spacecraft would
>have been more than 60 miles altitude as it passed the moon?

60 nm is a good "ballpark" figure for an Apollo pericynthion, but when
they first went into orbit, I believe that occured on the far side.
Figuring out if the panels would collide is more complicated than it
first appears...

To get that 60 nm pericynthion you have to be in the right place at
the right time. Change the speed that you travel, and you change
where you need to aim. They used mid-course corrections to make sure
the spacecraft was on exactly the right heading and the right speed to
get to the proper place at the right time. But the SLA panels were
stuck on whatever trajectory they were on when the TLI burn ended
(plus whatever lateral motion they were given when they separated.)

Roll the stack a little before TLI, and the panels are no longer
flying purely "right, left, up, and down" compared to the original
trajectory (I know there's no up or down in zero G, but if you try and
picture it, it makes sense).

It gets really complex in a hurry...

take care,
Scott

[Alan Erskine[_2_]]

"Rick Jones" > wrote in message
...
> I think that some of the writeups in Wikipedia (yes yes...) mention
> that years later what someone thought might be a new asteroid (?)
> turned-out to probably be a wayward Apollo stage.

It's probably accurate; the first few S-IVb's were put into 'Solar' orbit -
but that was far from circular - it was centred around both the Sun and
Earth, so they come home for a visit once in a while. I seem to recall that
the original argument for object was that it was too small and too bright to
be natural. Also, someone said the spectral analysis was of titanium
dioxide - white paint.

[OM[_6_]]

On Thu, 14 Aug 2008 08:51:00 +0100, Anthony Frost >
wrote:

>I did think it had been the other way round. Originally they were going
>to be hinged, but on one of the early flights (without LM) a panel stuck
>halfway so after that they were jettisoned. They went back to hinged for
>the Skylab flights.

....And went back to jettisoning the hinges for ASTP. The rule of hinge
appeared to be no hinges if an extraction was to take place, although
Apollo 8 was the exception to this rule solely because they did some
semblance of a transposition and docking manuover after S-IVB sep.
IIRC, tho, Borman expressed some concerns after the flight that he
would have preferred they still be attached to the S-IVB rather than
running the risk of them hitting A8(*).

(*) Anyone here still think this mission should *not* have been named
"Columbiad"?

OM
--
]=====================================[
] OMBlog - http://www.io.com/~o_m/omworld [
] Let's face it: Sometimes you *need* [
] an obnoxious opinion in your day! [
]=====================================[

[Pat Flannery]

Rick Jones wrote:
>
> I think that some of the writeups in Wikipedia (yes yes...) mention
> that years later what someone thought might be a new asteroid (?)
> turned-out to probably be a wayward Apollo stage.
>

Yeah, the one that went into solar orbit and came back past us decades
later; with way too low of mass to be a asteroid, plus spectral info
that it was covered with titanium oxide white paint.


Pa

[Pat Flannery]

wrote:
> My calculations show that a total of 36 SLA panels were jettisoned
> between Apollo 8 in 1968 and Apollo 17 in 1972.
> SInce the panels were jettisoned after TLI, my guess is that they went
> into solar orbit. The initial TLI burn of the S-IVB stage with the
> Apollo spacecraft attached
> had enough velocity to escape the Earth's gravity well, but not the
> Sun's.
> I doubt if they were ever tracked.
>

They may come right back around again and be mistaken for near-Earth
asteroids, the way the Apollo 12 S-IVB was:
http://web.mit.edu/newsoffice/2002/apollo.html

Pat

[Pat Flannery]

OM wrote:
>
> (*) Anyone here still think this mission should *not* have been named
> "Columbiad"?
>

Does that mean there should have been two dogs on it also? ;-)

Pat