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Brushing the LRV TV Lens

Copyright © 2007 by the Editors of Working on the Moon.
Last revised 23 August 2007.


    The last three Apollo LM crews - Apollos 15, 16, and 17 - had lens brushes made of fine, soft bristles (possibly camel hair) that were used during the EVAs to clean the lens on the Hasselblad film cameras and the lens of the TV camera mounted on the front of the Rover.  During preparation for Apollo 15, the possibility that the TV lens would require cleaning seems not to have been appreciated and, although Dave Scott and Jim Irwin frequently checked each other's Hasselblad lenses and brushed them as needed, they did not plan to inspect the TV lens.  In addition, despite the noticeable deterioration of the TV images - particularly when the camera is pointed upSun - at the stops during the EVA-1 traverse, Houston did not ask the crew to clean the lens.  However, early in EVA-2, as Dave and Jim were getting off the Rover at the first EVA-2 stop (Station 6), Houston indicated that they might ask them to clean the lens after assessing image quality.  The request was made prior leaving Station 6 and, thereafter, Houston asked the crew to clean the lens at several of the stops.  Lens cleaning always produced a noticeable - sometimes dramatic - improvement in image clarity.

    The following table lists material in the ALSJ relevant to lens cleaning an includes some "before" and "after" images.

(Apollo 17 yet to be done)

Apollo 15

Mission Elapsed Time Station Notes

Need a TV frame from before departure from the LM, perferably upSun.




Station 1
Effect of dust accumulated during the drive is evident in first image.  The TV camera is pointed down and aft, showing us the leftside battery cover.  Details indistinct.

Poor upSun visibility because of dust on the lens.  No lens dusting until EVA-2 Station 6.

TV frame (upSun?) from Station 1

Station 2
Here and elsewhere, they check each other's Hasselblad lens.
ALSEP site
Dirty lens at first TV
ALSEP site
Fendell pans around from west to north and the image quality degrades because of the dust.

EVA-2 preliminaries at the LM
They use the lens brush on their Hasselblad lens.  No one in Houston thinks to have them dust the TV lens.
Station 6
Shortly after they arrive at Station 6, but before Houston has a TV picture, Joe tells Dave that they may want the TV lens dusted.  It takes about 40 seconds before Joe can see a picture in the MOCR and, before that happens, Dave decides that he doesn't want to wait any longer for a decision and starts his preparations for sampling.
Station 6
"And troops, before we leave this area, we want you to brush the LCRU and the TV camera lens."
Station 6
Jim uses the lens brush on the TV lens and the big brush on the LCRU mirrors.  When he cleans the lens at 144:49:43, there is a dramatic improvement.

Before and after

145:32:05 Station 7
First TV images show that not much dust accumulated on the lens during the short drive from Station 6.
Station 4
On arrival at Dune Crater, Joe asks them to brush the TV lens with the lens brush but, then, after it is decided that this will be only a ten-minute stop without TV.  Hence, no lens dusting.
LM after EVA-2 traverse
Dave asks Houston if they wanted the TV lens dusted.  They do.  Dave comments that he will use the lens brush because, "I hate to put this big brush on that lens." The big brush is not used on the lens during A15.
Tech. Debrief comment
"We used the lens brushes on the (Hasselblad) cameras, and they were very good ... On the TV also.  That lens brush is really a good brush.  It cleaned it off very well."
EVA-3 preliminaries at the LM
They use the lens brush to clean off each other's Hasselblad.
Station 9
First TV after the drive out from the LM, noticeable, but not severe, image degradation.  No dusting till next station.
Station 9a
Joe asks Dave to dust the TV lens.  He uses the lens brush.

Before and after

EVA-3 Close-out at the LM
Joe asks that Dave to take "both dust brushes" to the VIP site, in part because the camera is getting too hot.  He doesn't actually dust the lens.
LM Liftoff
Because of problems with the TV's elevation clutch, Fendell did not try to track the LM but left the camera pointing at the descent stage.  See page 87 in the Apollo 15 Mission Report
A two-frame animation by Ulli Lotzmann and Ken Glover shows Falcon's descent stage before and after liftoff.  There doesn't appear to be any appreciable dust accumulation on the lens.

Apollo 16

Mission Elapsed Time
Station 1
Soon after arrival, but before Houston gets a picture, John dusts the TV lens.   He probably uses the big brush.
Station 2
Soon after arrival, John cleans the TV lens with the big brush.  Tony says, "That helps a lot."

before and after

EVA-1 close-out at the LM
After parking at the LM for the close-out, John briefly cleans the TV lens with the big brush.

Before and after

EVA-1 close-out at the LM
After John and Charlie dust each other, John cleans some dust off the LCRU that undoubtedly got sprayed on it when John fell at 125:32:23.  (Can we see that dust landing on the lens?) He notices some dust on the TV lens and cleans it thoroughly with the large brush.

Before and after

Station 4
Charlie notices that the TV lens is "pretty dirty", he cleans it with the lens brush.  (Are there any indications that use of the big brush has scratched the lens?)  After cleaning here at Station 4, the image still doesn't look all that great.  Or is that a function of source material Mark used?)

before and after

Station 6
Shortly after Houston gets a picture, John cleans the lens with the big brush.

 before and after

Station 8
Shortly after Houston gets a picture, John cleans the lens with the big brush.

before and after

Station 9
Soon after arrival, John cleans the lens with the big brush.

before and after

Station 10
After arrival at Station 10, John uses the big brush to clean the TV. 

before and after

Station 13
Soon after arrival, John cleans the lens with the big brush.

before and after

Station 10 Prime
Soon after arrival, John dusts the TV lens.

before and after

EVA-3 close-out  at the LM
John dust the TV lens with the large brush.
VIP Site
As John is parking the Rover, CapCom Tony England asks him to use the lens brush on the TV lens when he dusts it.  It is actually Charlie who dusts the lens, at 170:44:30

before and after

LM liftoff
Fendell has trouble keeping the LM in the field-of-view but captures it at intervals up to it becomes too faint to see at about 175:33:30.  He then pans down to look at the descent stage.

A two-frame animation by Henning Conrad shows not only the dust accumulation on the lens resulting from LM liftoff, but also orientation changes in the descent-stage struts and the two visible probes.

Apollo 17

Mission Elapsed Time Station
LM, LRV loading
The TV was stowed in the MESA until Gene was ready to install it on the front of the Rover

A side-by-side pair of up-Sun and down-Sun TV frames might go well here.

During the drive to the ALSEP site, the TV is pointed down and aft.
Gene turns the TV on after parking and aligning the high-gain antenna.

A side-by-side comparison of frames from before and after the drive, maybe cross-Sun?

Gene mentions that the TV's been dusted, but probably the radiator on top, rather than the lens.
Before turning the TV off and pointing it aft and down, Gene says the TV is "pretty clean, so I won't touch you."

Comparison of TV frames from the start of activities at the ALSEP site and now.  Cross-Sun?

Station 1
Gene turns the TV on. He doesn't dust the lens

Comparison of TV image before and after the drive to Station 1

Station 1
Gene turns the TV off

Comparison of start and end of Station 1

Gene turns the TV on and then dusts the battery covers, etc.  He doesn't dust the TV lens.

Compare before and after drive;
Any increase in dust from Gene's dusting at the front of the Rover?

TV off.

Any increase in dust during the SEP deployment?

TV on. 

Before and after the short drive to the LM

Gene has the lens brush, but does he use it?

Before and after Gene's dusting

TV off
TV on at the start of EVA-2

Before and after rest period

TV off prior to traverse

Any change?

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