MOL discussion

[kevin-rf]

Is that a new document? It is the first time I remember the optical layout being published.

It also brings up some interesting questions about unmanned, man out of the loop options and the great KH-9/KH-10 debate that occurred during Nixon.

I does answer the side looking question.

[Jim]

I does answer the side looking question.

Only for this timeframe, it could have changed later in the program.  Need all the history.

[ChileVerde]

I does answer the side looking question.

Only for this timeframe, it could have changed later in the program.  Need all the history.

I agree. There remain serious questions about what the final optical design looked like.  The model in the picture labeled "MOL Telescope/Camera" in http://blog.theavclub.tv/post/mol-update-4 suggests something closer to a Cassegrain design and is more consistent with the UL that the original 1.8 m mirrors for the Multiple Mirror Telescope were KH-10 leftovers.

Edit: And, of course, see http://www.thespacereview.com/article/1371/1

[Jim]

I agree. There remain serious questions about what the final optical design looked like.  The model in the picture labeled "MOL Telescope/Camera" in http://blog.theavclub.tv/post/mol-update-4 suggests something closer to a Cassegrain design and is more consistent with the UL that the original 1.8 m mirrors for the Multiple Mirror Telescope were KH-10 leftovers.

That isn't an original source

[ChileVerde]

I agree. There remain serious questions about what the final optical design looked like.  The model in the picture labeled "MOL Telescope/Camera" in http://blog.theavclub.tv/post/mol-update-4 suggests something closer to a Cassegrain design and is more consistent with the UL that the original 1.8 m mirrors for the Multiple Mirror Telescope were KH-10 leftovers.

That isn't an original source

Would you care to favor us with the original source?

[John Charles]

Thanks to ChileVerde for the link to The AV Club and two new (to me) MOL images from Douglas Aircraft Corp. In particular, the interior image addresses my question of more than a year ago, about whether there was a pressure hatch at the lab end of the transfer tunnel. If this image is as credible as it appears, and unless the hatch is hiding in the small area behind the rack on the right side of the image, then the answer appears to be: no. This is consistent with images of the mockup used for weightless tests on the KC-135, but not with some artwork that depicts a pressure hatch there. Of course, a pressure hatch might also have been removable (like the Apollo CM docking tunnel hatch) and just not installed in any of the mockups at the time the photos were made.

[simonbp]

I agree. There remain serious questions about what the final optical design looked like.  The model in the picture labeled "MOL Telescope/Camera" in http://blog.theavclub.tv/post/mol-update-4 suggests something closer to a Cassegrain design and is more consistent with the UL that the original 1.8 m mirrors for the Multiple Mirror Telescope were KH-10 leftovers.

Not really. The optical train depicted in Jim's image is almost identical to KH-8 and -9, with the exception that MOL apparently did not have the big Schmidt corrector plate that its predecessors did.

So, the full optical train would have been: big flat fold mirror up front (the bottom mirror in Jim's image), the primary focusing mirror in the extreme aft of the vehicle (these are what MMT inherited), and then two flat fold mirrors before a final (not depicted) coma corrector. You can kinda think of it as a classical Newtonian, with a few extra folds.

The upshot of this is that MOL would have had a "nose-first" orientation in orbit (like KH-8 and 9), not "nose-up" like most modern depictions show.

In answer to Blackstar's question from a while ago, it looks like at least one load of film would be sent down partway through the mission, though presumably not all. Could a film canister have fit between the crew's heads, in the space occupied by the hatch? I imagine the sequence would have involved one crewmen putting the film on his lap while the other closes the hatch, and then affixing the film in the space between them.

Anyone know if the parawing would have been used for Gemini B? It would certainly make sense in as much as protecting the film from seawater...

[ChileVerde]

Not really. The optical train depicted in Jim's image is almost identical to KH-8 and -9, with the exception that MOL apparently did not have the big Schmidt corrector plate that its predecessors did.

But I think Jim's point, to which I was attempting to agree, is that the system shown in the image is from the mid-1960s and may not represent what finally evolved a few years later.  There's some information that suggests that might have happened, and so I'd recommend caution in concluding that the folded, side-looking optical path shown in the image was the "final" KH-10 design.  Maybe it was, but there might be more to the story than that. 

I trust Blackstar will weigh in on this in the fullness of time.

[simonbp]

True, but the real kicker for me is the lack of holes in the MMT mirrors. If the mirror were supposed to be flown in an unfolded cassegrain configuration, it would almost certainly have had a center hole to get the beam to the cameras. A pickoff mirror (like MMT used) would have been unnecessarily complex for MOL.

Also, wasn't MOL supposed to have side-looking radar? That would have worked much better if mounted to the side of a horizontal optical tube.

[kevin-rf]

The primary mirror in the image that Jim posted is not by any stretch an f 1.8 primary. I thought MMT was provided with the mirrors that had already been figured, not blanks.

btw. For some reason I thought the original MMT mirrors where 72" not 70". Is this a metric english thing, or do I need to start taking some ginkgo root?

[ChileVerde]

The primary mirror in the image that Jim posted is not by any stretch an f 1.8 primary. I thought MMT was provided with the mirrors that had already been figured, not blanks.

btw. For some reason I thought the original MMT mirrors where 72" not 70". Is this a metric english thing, or do I need to start taking some ginkgo root?

AIUI, the MMT blanks as supplied by the USAF were flats, or pretty close to it, and then had to be heated and slumped to approximately the desired figure. Whether the USAF intended them to be used as flats in the originally envisaged application or was going to figure them further is unknown, at least to me.

On the diameter thing, I did a quick look this morning and found assertions that the MOL orbit was supposed to be at 150 miles (flavor of mile unspecified) and the desired resolution was 3 inches. (*)  If you take 150 statute miles and 3 inches as numbers to BOTE with, use the venerable resolution = range * 1.22 * lambda/D and use lambda = 5.5e-7 meters, you get D = 2.13 meters. Relaxing the resolution criterion to 4 inches gives a D of 1.6 meters.  These numbers are sort of consistent with the 1.8 meter MMT mirror diameter used as a primary.

(*)  Those numbers were from obviously secondary sources, and it would be a really good idea to find and catalogue, even post if possible, primary sources.

[Avclubvids]

You guys are amazing 

I have placed as many pics of the MOL as we could find here: https://www.dropbox.com/sh/jjqctsfcyvd6vrs/J-_m8T6z7o

I'll probably be moving them around and adding and removing, so grab any that you want now if I've got one that you want.

I also posted some thoughts on the side vs. down shooting camera here: http://blog.theavclub.tv/post/mol-update-5, so you guys can see what kinds of ancillary considerations all of this leads to for a film.

Keep it going, this is great stuff.

[kevin-rf]

Nice collection, thankyou.

Question. I've noticed most art from the period depicts MOL without solar panels. It seems to me that solar panels where added in more modern depictions.

Considering it was designed to live for a couple of weeks in a low orbit and it wasn't until the KH-9 and later models of the KH-8 that solar panels appeared on US recon birds. What are the chances it was not equipped with solar panels?

[ChileVerde]

You guys are amazing 

I have placed as many pics of the MOL as we could find here: https://www.dropbox.com/sh/jjqctsfcyvd6vrs/J-_m8T6z7o

I'll probably be moving them around and adding and removing, so grab any that you want now if I've got one that you want.

I also posted some thoughts on the side vs. down shooting camera here: http://blog.theavclub.tv/post/mol-update-5, so you guys can see what kinds of ancillary considerations all of this leads to for a film.

Keep it going, this is great stuff.

Thanks a bunch for the photos; they do show that, at least, there were a lot of different concepts floating around under the MOL umbrella.

FWIW, I think that the Astronomy Mission figure is somewhat close to the in-line Cassegrain KH-10 notion. The Schmidt and its primary would be replaced by the 1.8 meter Cassegrain primary and the Cassegrain secondary placed all the way back at the end of the barrel, underneath where the "Radiation Counters" thing is shown in the figure.

The interferometer in the figure is interesting, as others have mentioned hearing that KH-10 might have included an imaging radar. I never heard that myself, but if it's so that interferometer antenna might well have been a carry-over from the radar.

[AndyMc]

I am away from my Spacecraft Films disc, but the hatch was pushed "out" from the heatshield and stored in the tunnel.  There was a distinct lip on the hatch that overlapped the heatshield.  The storage compartment had some positive latch mechanism that prevented the hatch from floating up. 

When I last launched the video, I did not notice how the join was made air tight, perhaps someone else has the video at hand.

The astronauts tested their ability to go through the tunnel both in and out of suits, with film cartridges, and towing or pushing a suited/unsuited incapacatated astronauts.

Here's part of the video you are referring to, I think.

From the beginning ...

[ChileVerde]

The model in the picture labeled "MOL Telescope/Camera" in http://blog.theavclub.tv/post/mol-update-4 suggests something closer to a Cassegrain design and is more consistent with the UL that the original 1.8 m mirrors for the Multiple Mirror Telescope were KH-10 leftovers.

To ask the question before the thread ages too much, is the provenance of the model shown in that picture known?  If it traces back to actual program information, that would be somewhat significant. If it was just made to illustrate the UL of a Cassegrain design for KH-10, not so much.

Picture attached for reference.

[ChileVerde]

Here's the DORIAN section from the just-released 1966 NRO report to PFIAB.

[neilh]

The model in the picture labeled "MOL Telescope/Camera" in http://blog.theavclub.tv/post/mol-update-4 suggests something closer to a Cassegrain design and is more consistent with the UL that the original 1.8 m mirrors for the Multiple Mirror Telescope were KH-10 leftovers.

To ask the question before the thread ages too much, is the provenance of the model shown in that picture known?  If it traces back to actual program information, that would be somewhat significant. If it was just made to illustrate the UL of a Cassegrain design for KH-10, not so much.

Picture attached for reference.

I think the person who created that model is the same as the person who started the thread here, so you could probably just ask him: http://forum.nasaspaceflight.com/index.php?topic=29397.msg928795

[BrightLight]

How did they intend to isolate the vibrations from the  manned portion of the system from the optics - was the pressurized side "floating" in a shock absorber system?

[Dalhousie]

Having said that, the Russians slavishly copied MOL and executed missions with landing craft featuring hatches in the heat shield, although they never risked a crew landing with this architecture.

They didn't.  TKS-Amaz had a similar role, but was a very different concept in design and operation.