WEBVTT FILE

1
00:00:00.000 --> 00:00:02.900
Welcome to the NASA Goddard Space Flight Center

2
00:00:02.900 --> 00:00:03.900
where we're building the

3
00:00:03.900 --> 00:00:06.660
Laser Communication Relay Demonstration (LCRD).

4
00:00:06.660 --> 00:00:09.420
LCRD  is a technology demonstration mission

5
00:00:09.420 --> 00:00:11.490
that will use infrared lasers to send

6
00:00:11.490 --> 00:00:13.249
and receive data above gigabit

7
00:00:13.249 --> 00:00:15.529
per second in a relay capacity.

8
00:00:15.529 --> 00:00:17.800
Multiple systems going to the payload

9
00:00:17.800 --> 00:00:20.760
LCRD will carry two optical modules or telescopes

10
00:00:20.760 --> 00:00:22.470
where the data encoded lasers will be

11
00:00:22.470 --> 00:00:23.920
transmitted and received

12
00:00:23.930 --> 00:00:26.400
and two integrated modems to modulate the data

13
00:00:26.400 --> 00:00:27.720
onto the waves.

14
00:00:27.720 --> 00:00:29.099
Two control electronic

15
00:00:29.100 --> 00:00:31.120
boxes command the optical modules

16
00:00:31.120 --> 00:00:33.360
while a switching unit provides the ability to

17
00:00:33.360 --> 00:00:35.520
relay between the two sides of the payload.

18
00:00:35.520 --> 00:00:36.540
Today we're going to take a

19
00:00:36.540 --> 00:00:38.129
closer look at the optical modules and

20
00:00:38.129 --> 00:00:40.400
how we're developing those. Come on in.

21
00:00:40.400 --> 00:00:42.130


22
00:00:42.130 --> 00:00:44.710
Russell is the lead for LCRD's optical module

23
00:00:44.710 --> 00:00:46.090
development and he's going to show us how

24
00:00:46.090 --> 00:00:48.320
things are going today. How are you doing Russ?

25
00:00:48.320 --> 00:00:50.440
Great, you ready to take a look at the optical modules?

26
00:00:50.440 --> 00:00:52.000
Let's do it.

27
00:00:52.000 --> 00:00:56.960


28
00:00:56.960 --> 00:00:59.420
Now can you tell me about the optical module?

29
00:00:59.420 --> 00:01:01.420
What is it and what does it do?

30
00:01:01.449 --> 00:01:03.430
So the optical module is the device that points

31
00:01:03.430 --> 00:01:05.260
the down link beam at the ground station

32
00:01:05.260 --> 00:01:07.420
and it also gathers the light coming up

33
00:01:07.420 --> 00:01:08.770
from the ground station to the payload

34
00:01:08.770 --> 00:01:11.110
it responds to commands from the controller

35
00:01:11.110 --> 00:01:13.000
electronics and it's connected to modem

36
00:01:13.000 --> 00:01:14.780
via these two optical fibers.

37
00:01:14.780 --> 00:01:17.080
Ok,  I see now so

38
00:01:17.080 --> 00:01:19.270
can you break it down a little bit for me,

39
00:01:19.270 --> 00:01:21.369
I know there's a lot of smaller assembly

40
00:01:21.369 --> 00:01:23.200
that go into the overall optical module,

41
00:01:23.200 --> 00:01:25.980
like the gimbal, what's the gimbal what does that do?

42
00:01:25.980 --> 00:01:27.340
The gimbal is  right over here.

43
00:01:27.340 --> 00:01:29.340
The optical module has a two-axis gimball.

44
00:01:29.350 --> 00:01:32.050
One of the actuators controls east-west

45
00:01:32.050 --> 00:01:33.369
pointing when we're on orbit and the

46
00:01:33.369 --> 00:01:34.749
other one controls north-south.

47
00:01:34.749 --> 00:01:37.360
They both take extremely small steps

48
00:01:37.360 --> 00:01:40.960
OK, so mounted on the gimbal is

49
00:01:40.960 --> 00:01:42.909
the optical head, which is a combination of

50
00:01:42.909 --> 00:01:44.309
a few sub-assembles.

51
00:01:44.309 --> 00:01:47.200
What are those sub-assembles and what do they do?

52
00:01:47.200 --> 00:01:50.280
The Optical head is made up of the solar window assembly

53
00:01:50.280 --> 00:01:51.320
the optical assembly,

54
00:01:51.320 --> 00:01:52.460
which we can't see

55
00:01:52.460 --> 00:01:54.320
and the Inertial Stable Platform

56
00:01:54.320 --> 00:01:56.860
and the solar window assembly has a large mirror

57
00:01:56.860 --> 00:01:58.360
with a special optical coating.

58
00:01:58.360 --> 00:02:00.480
It's a mirror and most wavelength but it lets

59
00:02:00.480 --> 00:02:02.720
the LCRD wavelengths pass through.

60
00:02:02.720 --> 00:02:05.740
OK, alright, so I know in Lasercom

61
00:02:05.750 --> 00:02:08.030
you need the steady and stable beam in order

62
00:02:08.030 --> 00:02:10.090
to hit the ground station.

63
00:02:10.090 --> 00:02:12.450
How do you account for that on the spacecraft?

64
00:02:12.450 --> 00:02:14.550
How do you keep the beam steady?

65
00:02:14.550 --> 00:02:16.490
That's the job of the Inertially Stable Platform (ISP)

66
00:02:16.500 --> 00:02:18.960
so the optical assembly is mounted on the ISP

67
00:02:18.960 --> 00:02:21.940
and the ISP has some sensors that measures

68
00:02:21.940 --> 00:02:22.880
tip and tilt.

69
00:02:22.880 --> 00:02:25.180
It also has some actuators that are controlled

70
00:02:25.180 --> 00:02:26.900
by the controller electronics

71
00:02:26.900 --> 00:02:30.020
and those are commanded to minimize tip and tilt.

72
00:02:30.020 --> 00:02:34.480
OK, so I hear that the optical assembly is the

73
00:02:34.490 --> 00:02:36.980
most complex and complicated part of the

74
00:02:36.980 --> 00:02:38.300
optical module.  Why is that?

75
00:02:38.300 --> 00:02:39.900
Why is it so complicated?

76
00:02:39.900 --> 00:02:42.400
It is complicated.  It's made up of two different things

77
00:02:42.400 --> 00:02:44.740
there's a telescope that sits up front

78
00:02:44.740 --> 00:02:46.900
and then a small optics assembly in the back.

79
00:02:46.900 --> 00:02:48.620
The small optics assembly has

80
00:02:48.620 --> 00:02:51.280
several optics that about the size of a dime

81
00:02:51.280 --> 00:02:53.260
each have their own special coating

82
00:02:53.260 --> 00:02:55.420
that rowdy different LCRD wavelengths

83
00:02:55.420 --> 00:02:56.580
where they need to go

84
00:02:56.580 --> 00:02:57.800
and they're also

85
00:02:57.800 --> 00:03:00.280
actuators the small optics assembly that

86
00:03:00.280 --> 00:03:02.080
move the fibers around that are carrying

87
00:03:02.080 --> 00:03:03.380
the data.

88
00:03:03.380 --> 00:03:07.320
OK, speaking of actuators I heard that

89
00:03:07.320 --> 00:03:11.740
there's this rubber o-ring that's around the latch

90
00:03:11.740 --> 00:03:14.180
and in order to deploy the optical module

91
00:03:14.180 --> 00:03:16.800
you have to use paraffin actuators

92
00:03:16.800 --> 00:03:18.000
to deploy it, can you talk to

93
00:03:18.000 --> 00:03:20.360
me about that?  What are the paraffin actuators?

94
00:03:20.360 --> 00:03:21.900
Sure we need to have the OM

95
00:03:21.900 --> 00:03:24.959
like this stowed at launch that way the

96
00:03:24.959 --> 00:03:27.000
latch covers the solar window assembly

97
00:03:27.000 --> 00:03:29.060
and supports the optical head

98
00:03:29.060 --> 00:03:31.820
and when we get on orbit we warm up the wax and

99
00:03:31.820 --> 00:03:34.040
one of the paraffin actuators down here.

100
00:03:34.040 --> 00:03:36.620
When it warms up it acts as a pin puller

101
00:03:36.620 --> 00:03:39.891
the latch rotates back and then we can begin operations.

102
00:03:39.900 --> 00:03:42.700
Awesome! Can go check out the test set up?

103
00:03:42.700 --> 00:03:43.200
Sure!

104
00:03:43.200 --> 00:03:43.800
Thanks!

105
00:03:43.800 --> 00:03:45.000


106
00:03:45.000 --> 00:03:47.340
Now this is a really impressive setup is

107
00:03:47.340 --> 00:03:48.959
this where you test the optical modules?

108
00:03:48.960 --> 00:03:51.060
It is, we put the optical module right

109
00:03:51.060 --> 00:03:52.980
here on the jitter table and for some

110
00:03:52.980 --> 00:03:55.170
tests we use these small shakers to disturb

111
00:03:55.170 --> 00:03:57.120
the optical modules. We need to make sure

112
00:03:57.120 --> 00:03:58.590
that the Inertial Stable Platform is

113
00:03:58.590 --> 00:03:59.720
doing its job.

114
00:03:59.720 --> 00:04:01.620
Our host spacecraft has moving parts

115
00:04:01.620 --> 00:04:03.660
which generate disturbances.

116
00:04:03.660 --> 00:04:06.480
OK,  and over here I noticed that there's

117
00:04:06.480 --> 00:04:08.480
these really cool looking mirrors.

118
00:04:08.480 --> 00:04:10.800
Why do you need so many of them?

119
00:04:10.800 --> 00:04:13.580
Well these large flat mirrors are for aligning the optical

120
00:04:13.580 --> 00:04:15.080
modules to the optimal test set

121
00:04:15.080 --> 00:04:17.239
and we have three of them because we want to be

122
00:04:17.240 --> 00:04:18.980
able to set up two optical modules

123
00:04:18.980 --> 00:04:21.040
for testing at the same time.

124
00:04:21.520 --> 00:04:22.360
Awesome!

125
00:04:22.580 --> 00:04:25.080
And I noticed the thermal vacuums is in here too.

126
00:04:25.080 --> 00:04:27.800
Besides when the optical modules are integrated

127
00:04:27.800 --> 00:04:29.210
with the payload and the payload goes

128
00:04:29.210 --> 00:04:30.890
off to be made it with the host

129
00:04:30.890 --> 00:04:32.530
spacecraft with the optical modules ever

130
00:04:32.540 --> 00:04:33.740
leave the cleanroom?

131
00:04:33.740 --> 00:04:36.120
The only time to leave is for vibration testing

132
00:04:36.120 --> 00:04:37.940
and that's because we don't need the optical test set

133
00:04:37.940 --> 00:04:38.740
for that.

134
00:04:38.740 --> 00:04:40.680
For everything else we need the OTS

135
00:04:40.680 --> 00:04:42.780
it's very big, it took a long time to assemble

136
00:04:42.780 --> 00:04:43.500
in the line

137
00:04:43.500 --> 00:04:45.760
so instead of moving the OTS, we bring the test

138
00:04:45.760 --> 00:04:46.640
equipment in here,

139
00:04:46.640 --> 00:04:48.330
including the thermal vacuum chamber.

140
00:04:48.330 --> 00:04:50.560
Russ, thank you so much for letting us come in here today

141
00:04:50.570 --> 00:04:52.730
and learn more about the optical modules

142
00:04:52.730 --> 00:04:55.430
Want to learn more about LCRD?

143
00:04:55.440 --> 00:04:58.560
Visit LCRD.GSFC.NASA.GOV

144
00:04:58.560 --> 00:05:01.980