SLA question

"Anthony Frost" wrote in message
...
In message tatelephone
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.

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...

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.

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...

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

"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.

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
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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

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

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