Brushing the LRV TV Lens
Copyright © 2007 by the Editors of Working on the
Moon.
Last revised 23 August 2007.
Summary
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. |
||
| 122:12:27 122:16:23 122:21:35 122:26:09 |
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 |
||
| 123:16:17 |
Station 2 |
Here and elsewhere, they check
each other's Hasselblad lens. |
| 124:32:29 |
ALSEP site |
Dirty lens at first TV |
| 125:07:06 |
ALSEP site |
Fendell pans around from west to
north and the image quality degrades because of the dust. |
| 142:51:19 |
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. |
| 143:55:47 |
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. |
| 144:41:42 |
Station 6 |
"And troops, before we leave
this area, we want you to brush the LCRU and the TV camera lens." |
| 144:48:14 |
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. |
| 146:28:43 |
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. |
| 147:22:04 |
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. |
| 160:25:00 |
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." |
| 164:02:07 |
EVA-3 preliminaries at the LM |
They use the lens brush to clean
off each other's Hasselblad. |
| 165:02:51 |
Station 9 |
First TV after the drive out
from the LM, noticeable, but not severe, image degradation. No
dusting till next station. |
| 165:20:46 |
Station 9a |
Joe asks Dave to dust the TV
lens. He uses the lens brush. |
Before and after |
||
| 167:26:33 |
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. |
| 171:36:25 |
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 |
Notes |
| 123:26:10 |
Station 1 |
Soon after arrival, but before
Houston gets a picture, John dusts the TV lens. He probably
uses the big brush. |
| 124:24:12 |
Station 2 |
Soon after arrival, John cleans
the TV lens with the big brush. Tony says, "That helps a lot." |
before and after |
||
| 125:15:24 |
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 |
||
| 125:35:06 |
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 |
||
| 144:17:54 |
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 |
||
| 146:09:54 |
Station 6 |
Shortly after Houston gets a
picture, John cleans the lens with the big brush. |
before and after |
||
| 146:45:12 |
Station 8 |
Shortly after Houston gets a picture, John cleans the lens with the big brush. |
before and after |
||
| 147:56:35 |
Station 9 |
Soon after arrival, John cleans the lens with the big brush. |
before and after |
||
| 148:58:07 |
Station 10 |
After arrival at Station 10,
John uses the big brush to clean the TV. |
before and after |
||
| 168:21:38 |
Station 13 |
Soon after arrival, John cleans
the lens with the big brush. |
before and after |
||
| 169:20:59 |
Station 10 Prime |
Soon after arrival, John dusts
the TV lens. |
before and after |
||
| 169:54:42 |
EVA-3 close-out at the LM |
John dust the TV lens with the
large brush. |
| 170:26:53 |
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
|
||
| 175:31:49 |
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 |
Notes |
| 118:14:22 |
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. |
||
| 119:04:15 |
LM |
During the drive to the ALSEP
site, the TV is pointed down and aft. |
| 119:12:54 |
ALSEP |
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?
|
||
| 119:14:52 |
ALSEP |
Gene mentions that the TV's been
dusted, but probably the radiator on top, rather than the lens. |
| 121:36:13 |
ALSEP |
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?
|
||
| 122:07:01 |
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
|
||
| 122:32:36 |
Station 1 |
Gene turns the TV off |
Comparison of start and end of Station 1 |
||
| 122:54:54 |
SEP |
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? |
||
| 123:13:20 |
SEP |
TV off. |
Any increase in dust during the
SEP deployment?
|
||
| 123:18:35 |
LM |
TV on. |
Before and after the short drive
to the LM
|
||
| 123:29:38 |
LM |
Gene has the lens brush, but
does he use it? |
Before and after Gene's dusting
|
||
| 123:31:53 |
LM |
TV off |
| 140:45:27 |
LM |
TV on at the start of EVA-2 |
Before and after rest period
|
||
| 141:21:30 |
LM |
TV off prior to traverse |
Any change? |
||
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