Optical Communications extended to Deep Space CL24_5778.pdf

Optical Communications extended to Deep Space

1. © 2024 California Institute of Technology Government sponsorship acknowledged.
Jet Propulsion Laboratory
California Institute of Technology
Optical communications extended to
deep space
Abhijit (Abi) Biswas
Group Supervisor, Optical Communications Systems
Jet Propulsion Laboratory, California Institute of Technology
The work described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the
National Aeronautics and Space Administration (80NM0018D0004).

2. © 2024 California Institute of Technology Government sponsorship acknowledged.
2
Outline
•Background
•Deep Space Optical Communications (DSOC) Overview
•System Description
•Flight Laser Transceiver (FLT)
•Ground Laser Transmitter (GLT)
•Ground Laser Receiver (GLR)
•Operational Results
•Plans Forward
•Future Infusion and Summary

3. © 2024 California Institute of Technology Government sponsorship acknowledged.
Brief History of Space-Ground Communications
•Space-ground communications started in the late
1950’s and has progressed ever since
•So-called satellite communications can be classified
in different ways, here we consider
−Commercial (radio, telephony, TV …)
−Military
−Science and Exploration missions
−NASA and other space agencies
−Notional representation in graphic
Space Communications and Navigation (SCaN) Network Architecture Definition Document (ADD) April 2014
•A common feature of nearly all these operational
missions is the use of radio frequency
communications
−S-band, X-band, Ka-band etc.
3

4. © 2024 California Institute of Technology Government sponsorship acknowledged.
4
History of Deep-Space Communications

5. © 2024 California Institute of Technology Government sponsorship acknowledged.
•Light Amplification by Stimulated Emission (LASER) discovered in 1960 in Hughes Research Laboratory (HRL)
−Theodore Maiman
−Laser light is coherent light
−Ever since its invention lasers were identified as a means of communications
−Took shape initially as fiber-optic communications that span the entire globe today
Laser Communications
Incoherent
light
Coherent
light
Transmitter
Receiver
100 -1000 Gbits/channel common to use multiple channels
•Since 1990’s laser technology was sufficiently advanced to demonstrate operations from spacecraft to
the ground - advent of free-space optical communications (FSOC)
5

6. © 2024 California Institute of Technology Government sponsorship acknowledged.
Laser communications or lasercom operates at orders of magnitude
higher frequency, or shorter wavelength, than state-of-art telecom
‒Beam-Width ~ /D, where  is wavelength and D is the aperture diameter
‒ Prospects
‒Narrow beams - more power density higher information rate
‒At least 10  increase in data-rate compared to sate-of-art telecommunications
‒Jam resistant
‒Unregulated bandwidth – RF spectrum is highly regulated
‒Oversubscription of ground networks
‒Consequences
‒Requires high pointing accuracy
‒Obstructed by clouds so requires clear weather
‒Atmospheric propagation of lasers causes aberrations requires complex corrective
measures
Electromagnetic Spectrum
X-bandKa-bandLasers (near-infrared)
Comparing Psyche X-band and DSOC optical
2.6 AU (Notional Mars image)
~ 400 earth diameters
D = 2 m
D = 0.22m
0.15 earth diameter
Free-space optical communications
6

7. © 2024 California Institute of Technology Government sponsorship acknowledged.
Low-Earth Orbit Technology Demonstrations
Launch 2013
ISS to Ground
Downlink 50 Mb/s
2014-2016
Launch 2021
https://en.wikipedia.org/wiki/Optical_Payload_for_Lasercomm_Science#cite_ref-:0_7-4
https://www.autoevolution.com/news/satellite-that-beamed-down-48-tb-of-data-in-5-minutes-
while-doing-17k-mph-dies-on-the-job-240445.html

8. © 2024 California Institute of Technology Government sponsorship acknowledged.
8
Launch 2023
Launch 2022
Geostationary Orbit Technology Demonstrations
https://www.nasa.gov/directorates/stmd/tech-demo-missions-program/laser-communications-relay-
demonstration-lcrd-overview/
https://www.nasa.gov/missions/illuma-t/

9. © 2024 California Institute of Technology Government sponsorship acknowledged.
9
Launch 2025
Lunar Orbit Laser Communications
https://www.nasa.gov/mission/lunar-laser-communications-demonstration-llcd/
LLCD on LADEE 2013-2014 (Ames)
Optical-to-Orion (O2O) planned
for first crewed mission on
ARTEMIS II
https://www.nasa.gov/directorates/somd/space-communications-navigation-program/nasa-laser-
communications-terminal-delivered-for-artemis-ii-moon-mission/

10. © 2024 California Institute of Technology Government sponsorship acknowledged.
•Table of NASA’s past and planned optical communications demonstrations
Name Year Distance
(AU)
Data-Rate (Mb/s)
Lunar Laser Communications Demonstration (LLCD) on board
LADEE spacecraft orbiting Moon
2013 2.7E-3 622 Down
20 Up
Optical Payload for Lasercom Science (OPALS) 2014-
2016
1.3E-5 50 Down
Laser Communications Relay Demonstration (LCRD) 2021-
2023
2.7E-4 1200 Down/Up
Deep Space Optical Communications (DSOC) 2021-
2024
0.1 to
2.5
8 - 267 Down
0.0018 Up
Terabyte Infrared Delivery (TBIRD), [not shown on previous
slide]
2022 1.3E-5 200000
ILLUMA-T 2022 3.2E-4 1440 Down
300 Up
Optical-to-Orion (planned) 2025 2.7E-3 80-260 Down
10-20 Up
AU – Astronomical Units (1.49 E8 Km)
Mb/s – Megabits per second
NASA’s Lasercom Background
10

11. © 2024 California Institute of Technology Government sponsorship acknowledged.
11
Outline
•Background
•Deep Space Optical Communications (DSOC) Overview
•System Description
•Ground Laser Transmitter (GLT)
•Flight Laser Transceiver (FLT)
•Ground Laser Receiver (GLR)
•Operational Results
•Plans Forward
•Future Infusion and Summary

12. © 2024 California Institute of Technology Government sponsorship acknowledged.
Deep Space Optical Communications (DSOC)
•NASA’s first optical communications technology demonstration from beyond the earth-
moon system
•Targeting communications from Mars distances ( 0.4 – 2.7 AU about 60 – 400 million
kilometers)
•Compared to Moon distance ~ 400,000 Km, 1000  increase
•Electromagnetic wave power density decreases by inverse distance squared
Psyche/DSOC Falcon Heavy launch Oct. 13, 2023.
12
•Link difficulty - Mb/s  AU
2
increases a million times (1E6) compared to the moon
•Covering this enormous gap required new technologies and scaling
•DSOC has been in the making for nearly 15 years and required
•Identifying a viable architecture
•Developing technologies that could instantiate the architecture into a design
•Both flight and ground side of the link
•Implementing and testing the technologies
•Finding a “ride” i.e. a host spacecraft
•Integration to the spacecraft followed by launch and operations

13. © 2024 California Institute of Technology Government sponsorship acknowledged.
FLIGHT LASER TRANSCEIVER (FLT)
22 CM DIA.
4W AVG. POWER
GROUND LASER TRANSMITTER (GLT)
TABLE MTN., CA
1M-OCTL TELESCOPE
(5 KW LASER POWER)
GROUND LASER RECEIVER (GLR)
PALOMAR MTN., CA
5M-DIA. HALE TELESCOPE
DSOC Mission
Operation System
(MOS)
PSYCHE MOS
PSYCHE SPACECRAFT
(LAUNCHED OCT. 2023)
X-Band
PSYCHE TELECOMM CMD/TLM
GLR VOICE/CMD/TLM
GLT VOICE/CMD/TLM
DEEP SPACE OPTICAL
COMMUNICATIONS
13

14. © 2024 California Institute of Technology Government sponsorship acknowledged.TRANSMIT
SIGNAL
TRANSMIT SIGNAL
LINE-OF-SIGHT
RETRO
MIRROR
RECEIVER
FOCAL
PLANE ARRAY
TELESCOPE
OPTICS
PONT
AHEAD
ANGLE
BEACON
SOURCE
DIRECTION OF
APPARENT
BEACON
MOTION
FINE-POINTING MIRROR
TRANSMIT
SIGNAL
TRANSMIT SIGNAL
LINE-OF-SIGHT
RETRO
MIRROR
RECEIVER
FOCAL
PLANE ARRAY
TELESCOPE
OPTICS
PONT
AHEAD
ANGLE
BEACON
SOURCE
DIRECTION OF
APPARENT
BEACON
MOTION
FINE-POINTING MIRROR
DICHROIC
BEAM SPLITTER
POINT-AHEAD MIRROR
1064 nm
1550 nm
BEACON BASED ARCHITECTURE
LASER BEACON
SOURCE
Beacon based architecture
•Beacon serves as pointing reference to send downlink laser beam back to
ground receiver
−Downlink pointing must include point-ahead angle (maximum of 20 beam
diameters)
•Downlink received on ground closes the optical link and data transfer
can occur for duration of contact
•Relative velocity between the source and target causes the familiar
Doppler shift

∆� =
∆??????
??????
�
0
−If filter spectral width >> ∆� then nothing is required otherwise optical and electrical
waveforms need to be shifted or tracked
14

15. © 2024 California Institute of Technology Government sponsorship acknowledged.
https://medium.com/the-nasa-psyche-mission-journey-to-a-metal-worldSchedule constraint
•NASA’s Psyche Mission is hosting the DSOC technology demonstration
‒Selected by NASA/Discovery Program to explore the asteroid Psyche-16
‒Notional DSOC contacts in 1
st
year of cruise indicated by Blue dots
LAUNCH
October 13, 2023
EARTH
Approach
checkout
100d
May 2026
>5750 km
MARS
GRAVITY ASSIST
PSYCHE
CAPTURE
Aug 2029
MARS
Sep. 2025
Jan. 2025
Jul. 2024
Psyche Mission
15

16. © 2024 California Institute of Technology Government sponsorship acknowledged.
16
Outline
•Background
•Deep Space Optical Communications (DSOC) Overview
•System Description
•Ground Laser Transmitter (GLT)
•Flight Laser Transceiver (FLT)
•Ground Laser Receiver (GLR)
•Operational Results
•Plans Forward
•Future Infusion and Summary

17. © 2024 California Institute of Technology Government sponsorship acknowledged.
FS Functional Block Diagram of FLTOptical Transceiver
Assembly (OTA)
Point
Ahead
Mirror
(PAM)
Photon Counting
Camera (PCC)
Thermal
Monitor &
Control
(TMC)
Laser Collimator
Laser
Transmitter
Assembly
(LTA)
Isolation Pointing Assembly
(IPA)
Floating
Platform
Electronics
(FPE)
Stationary
Platform
Electronics
(SPE)
Optical Fiber
Data/Pwr
Ext.
I/F
•Flight Laser Transceiver (FLT) on-board Psyche spacecraft
•Spacecraft points toward GLT but lacks control for accurate pointing
•FLT uses a set of isolation point struts with actuators and sensor to search
for the uplink signal and “lock’ in on the PCC focal plane
17
Transmit Optical Path
Receive Optical Path

18. © 2024 California Institute of Technology Government sponsorship acknowledged.
More FLT Technologies
•High peak-to-average power laser
−4 W average power > 600 W of peak power
−Low jitter pulses 0.5, 1, 2, 4, 8 nanoseconds
−Two units built and qualified for space environment
•Geiger Mode Avalanche Photo Diode Array Camera
−Operate avalanche photo diode biased above breakdown
−Single photon triggers an “avalanche” of carriers senses as an electrical pulse
Mark A. Itzler et al. SWIR Geiger Mode APD detectors for 3D Imaging
SPIE Proceedings, 2014
J. M. Dailey et al. High output power transmitter
for high efficiency deep-space optical
communications, Proc. SPIE, 2019
18

19. © 2024 California Institute of Technology Government sponsorship acknowledged.
19
SEM
LTA
DSOC
Aperture Cover
DAK
FEM
PCC
IPA
Strut
LL
HGA
PCC
FLT Sub-System
•View of actual FLT hardware developed, tested, integrated and now flying in space with Psyche spacecraft
OTA- Optical transceiver assembly
FEM-Floating Electronics Module
PCC-Photon Counting Camera
IPA- Isolation Pointing Strut
LL- Launch Lock
LTA-Laser Transmitter Assembly
DAK-DSOC accommodation kit
Sun-shade for
solar
protection
DSOC is co-boresighted
to High Gain Antenna
(HGA)

20. © 2024 California Institute of Technology Government sponsorship acknowledged.
DSOC Downlink Signaling
‒High peak-to-average power ratio (160:1)
‒Pulse-position-modulation (PPM)
‒variable M = 16, 32, 64, 128; and slot widths Ts = 0.5,1,2,4,8 ns
‒Slot/symbol/frame synchronization features:
‒Inter-symbol guard time (ISGT) slots (M/4) and code word sync marker (CSM) sequences
‒Near-channel-capacity forward error correction:
‒serially concatenated convolutionally coded PPM (SC-PPM) with variable code rates (Τ
1
3, Τ
1
2 , Τ
2
3)
‒Interleaving for fading mitigation: convolutional channel inter-leaver
‒Distributes deep fades across code words to allow decoder to work (3 dB recovered)
‒Designed with 2.7sec depth for all data rates (based on pointing jitter estimates)
‒Lower data rates for far ranges
‒with symbol repeat factors and slot-widths (0.5 – 8 ns) - enable multitude of rates
•Downlink signaling follows an emerging High Photon Efficiency (HPE)
standard
−Consultative Committee for Space Data Systems (CCSDS) Standard
…
M-PPM symbol
guard slots
M-PPM symbol
guard slots
Pulse-position modulation (PPM)
Fading causes
burst outages
Decoder corrects more
errors spread across
codewords by inter leaver
20

21. © 2024 California Institute of Technology Government sponsorship acknowledged.
21
Outline
•Background
•Deep Space Optical Communications (DSOC) Overview
•System Description
•Ground Laser Transmitter (GLT)
•Flight Laser Transceiver (FLT)
•Ground Laser Receiver (GLR)
•Operational Results
•Plans Forward
•Future Infusion and Summary

22. © 2024 California Institute of Technology Government sponsorship acknowledged.
2.7 AU case
Uplink + Earth
Sum counting
Uplink
Up-down counting
2.7 AU case
22
Laser
Transmitter
Assembly
Data
Formatter
2-PPM (100% ISGT)
Ground
Telescope
Randomly varying refractive index cells
Beam diameter  atmospheric cell size
Wind
Ground Laser Transmitter (GLT) Functions
•Key GLT functions are to deliver a laser signal to the FLT over 0.1 – 3 AU for:
−Acquisition, tracking (serves as a pointing reference) and low-rate (1.8 kbps) communications
−Minimum mean irradiance at threshold
−Fluctuations due to atmospheric turbulence factored in
−Wavelength matches FLT spectral filter bandpass
−Modulated signal that allowsRRatmspaceingpoTTtxavgrxavg
GGPP  =
int__
P – power
G – gain
η – efficiency
T – Transmitter;
R – Receiver; atm – atmosphere
Pointing – loss due to beam misalignment
Space – distance that beam travels
atm – atmospheric transmission
−Gain (G) is related to directionality of beam
4 sr
Beam divergence
−Pointing Loss (
pointing) depends on telescope mount stability and accuracy
•Uplink lasers are modulated i.e. turned “on” and “off”
−Allows background subtraction and communications
Beacon + uplink data mode: 2-PPM + 100% guard-time
Beacon-only mode: 50% duty cycle square wave
~65 μs

23. © 2024 California Institute of Technology Government sponsorship acknowledged.
Ground Laser Transmitter (GLT)
Optical Communication Telescope Laboratory (OCTL) 1m aperture Az/El Drive, 1m diameter, F# 76
•DSOC technology demonstration would utilize
−Ground Laser Transmitter at OCTL telescope near Wrightwood, CA
−Develop an optical train for coupling 10  500 W (avg. power) fiber amplified lasers to the OCTL telescope
−The Uplink Laser Assembly (ULA) beams are transmitted through sub-apertures of primary mirror
−Mount pointing and ephemeris predication accuracy used for pointing Uplink to Psyche spacecraft
Dome
Coude Room
GLT Optics
Assembly
M6
M7
M5
M4
M3M2
M1
Coude focus
23
Uplink lasers on sky

24. © 2024 California Institute of Technology Government sponsorship acknowledged.
Outdoor Laser Safety System
2.3 km [MSL] OCTL altitude
5.5 km [MSL]
Tier 2: FAA Data Feed
18.3 km [MSL]
Tier 3: Predictive Avoidance File
•Lasers will be shuttered below 20
O
elevation.
•Tier 1 and 2 overlap region will be used to test reliability
of tier 1 and 2.
Class A Airspace
Tier 1 purpose to detect non-interrogated aircrafts flying beneath the class A airspace.
•4 thermal
•2 visible
Tier 1: Thermal/Visible Cameras
Overlap Region
24

25. © 2024 California Institute of Technology Government sponsorship acknowledged.
25
Outline
•Background
•Deep Space Optical Communications (DSOC) Overview
•System Description
•Ground Laser Transmitter (GLT)
•Flight Laser Transceiver (FLT)
•Ground Laser Receiver (GLR)
•Operational Results
•Plans Forward
•Future Infusion and Summary

26. © 2024 California Institute of Technology Government sponsorship acknowledged.
Ground Laser Receiver (GLR)
•The DSOC GLR is built around the P200-inch (Hale Telescope) at Palomar Observatory
−Availability and accommodation at the observatory is enabling for the DSOC TD
−Through an early trade in partnership with Caltech Optical Observatories (COO) the 3-mirror coude
configuration was selected
26
GLR in Coudé spectrograph room
Electronics racks
GDA cryostat
GLR optics bench
Coudé
spectrograph
room
Electronics racks
GDA cryostat
GLR Optics
Cryo-compressor
Coudé focus
Packaged SNSPD detector array 64- channels

27. © 2024 California Institute of Technology Government sponsorship acknowledged.
•Superconducting Nanowire Single Photon Detectors (SNSPDs) are the highest performing detectors
available for time-resolved photon counting
•1 Kelvin operating temperature
•SNSPD arrays for DSOC are made at MDL: inhouse design, fabrication, and testing at JPL
•DSOC detector is a 64-pixel 320-µm diameter active area WSi SNSPD array
•4 spatial quadrants with 16 nanowire sensor elements each
GLR Technologies: SNSPD
Vertical Cavity Design to Enhance Absorption
Device Operation Concept
Electron microscope detail of
320-µm active area tungsten
silicide ( Wsi)
superconducting nanowire
single photon detector
(SNSPD) array
Ground
Technology
04-27
27

28. © 2024 California Institute of Technology Government sponsorship acknowledged.
28
Outline
•Background
•Deep Space Optical Communications (DSOC) Overview
•System Description
•Ground Laser Transmitter (GLT)
•Flight Laser Transceiver (FLT)
•Ground Laser Receiver (GLR)
•Operational Results
•Future Infusion and Summary

29. © 2024 California Institute of Technology Government sponsorship acknowledged.
29
GLT
FLT
GLR
DSOC
MOS
DSN
PSYCHE
MOS
LCH
FAA
Feed
COO
PSYCHE
1553
UndockLaser Uplink
1064 nm
Mission Net
Laser Downlink
1550.12 nm
X-Band/LGA
CHILL
VOCA
TCS
VOCA
Open MCT
/CHILL
/VISTA
Open MCT
/CHILL
/VISTA
L3-Harris
PA Files
FLT
Ops VOCA
MTIF
Mission Operations (MOS)
•Mission operations conducted under Operations Manager oversight, supported by Flight Ops, GLR and GLT leads
−Cream shaded boxes are key DSOC operational nodes
−Auxiliary grayed out boxes are critical for successful DSOC operations
•DSOC was in commissioning phase from Oct. 25 – Dec. 12
−In addition to initial one-time activities commissioning allowed more interactive but slower mode of operations
−Needed Psyche staff of be on hand for radiating RF commands
•Fully sequenced phase since Jan. 1, 2024
−FLT activities are pre-sequenced and ground activities coordinated
−No staffing from Psyche required for nominal ops

30. © 2024 California Institute of Technology Government sponsorship acknowledged.
30
0.175 AU
uplink
beacon
downlink
retro-spot
illuminated Earth
0.36 AU 0.71 AU 1.5 AU 2.17 AU 3.1 AU
daytime pass
1.5 AU
PCC Images
•The photon counting camera images recorded from different distances
−Illuminated limb of earth
−Gets smaller with distance and more circular due to earth-fraction illuminated increasing
− The uplink laser spot is imaged in the center of the PCC focal plane
− A mall portion of the internally retro-reflected downlink also imaged
− As the distance and point-ahead angle increase the downlink spot migrates outside the focal plane
After background
subtraction

31. © 2024 California Institute of Technology Government sponsorship acknowledged.
31
•Typical signal (Ks) and background (Kb) counts measured by the PCC and logged at 1 Hz during tracking
−Back calculate irradiance from measured Ks and Kb values
•Centroid estimates on a 2  2 pixel window around the designated cross-hair on PCC ( Mar. 19, 1.2 AU)
Signal Counts (ks)
Noise Counts (kb)
•High-rate (15 kHz) slot statistics to evaluate atmospheric channel effects
−Correlation with independent channel conditions on ground is pending
PCC Counts and Centroids

32. © 2024 California Institute of Technology Government sponsorship acknowledged.
GLR BIAS ESTIMATE: (+0.89, -0.2) URAD
GLT BIAS ESTIMATE: (+0.86, -4.6) URAD
GLT UPLINKS POINTING
OFFSET COMMAND TO FLT
Downlink Pointing
•Residual downlink pointing errors corrected during passes
‒5 minute pointing scans provide beam power profiles for
estimating biases instantaneously.
‒Downlink pointing is corrected via uplink optical
commanding when possible.
‒Commanding back to DSOC 1 light time.
Uplink Laser power
Laser Safety
interruptions

33. © 2024 California Institute of Technology Government sponsorship acknowledged.
33
•Downlink performance measured exceeds predictions
−Operated DSOC LTA de-rated at 2 W. Full power is 4 W.
−Total downlink volume of 10.8 Tbits so far
−Accounting for predicted versus operating margins
−Observed 3 – 4 dB improvement
−2-3 dB from better pointing
−1-dB from reduced FLT losses
Lines show inverse distance
square dependence

34. © 2024 California Institute of Technology Government sponsorship acknowledged.
34
Outline
•Background
•Deep Space Optical Communications (DSOC) Overview
•System Description
•Ground Laser Transmitter (GLT)
•Flight Laser Transceiver (FLT)
•Ground Laser Receiver (GLR)
•Operational Results
•Future Infusion and Summary

35. © 2024 California Institute of Technology Government sponsorship acknowledged.
•Data volume enables new engineering and science product delivery
•Mission to Earth-Sun Lagrange points (L1, L2, L4, L5)
•Can use as-built DSOC flight technology, possibly existing ground assets (L1/L2)
•High-rate deep space communications from Mars farthest range to service 20 Mb/s
forward and 100 Mbps return will require
•Scaling of DSOC FLT to increase the equivalent isotropic radiated power (EIRP)
from 2.7 AU
•Effective ground apertures of 5-8 m diameter that can operate in the daytime at
<2° sun-earth probe (SEP) angles
•High-rate uplink lasers and flight-receivers
Data Processing
Center
DAYTIME OPERATIONS
•Spectral, spatial and temporal filtering on the ground needed to
lower the additive background
•Will reduce required EIRP on spacecraft (SWaP saving)
•Concepts for protecting ground assets from solar damage while
near sun-pointing are under study
•Increases link availability by avoiding low SEP outage
GROUND COLLECTOR CONCEPTS
https://www.nasa.gov/humans-in-space/humans-to-mars/
Future Infusion

36. © 2024 California Institute of Technology Government sponsorship acknowledged.
36
Summary
•Extended the reach of lasercom to Mars like planetary distances from
the moon – a 1000 x increase in distance
•Future human exploration of Mars and high-resolution science will be
enabled by infusing the DSOC technology into operational missions
•Ground infrastructure is still needed for NASA to operate to Mars
distance
Pre-recorded ultra-high-definition video
Loop-back images returned from ground-to-space and back

37. © 2024 California Institute of Technology Government sponsorship acknowledged.
37
BACKUP

38. © 2024 California Institute of Technology Government sponsorship acknowledged.
NASA’s Need
•Since Explorer 1 and Pioneer data-rates have increased by many orders of magnitude
“…Regardless of mission set scenario, average data rates will increase roughly two orders of
magnitude over the next 20 years
**
…”
•Future human exploration and high-resolution science missions
•Higher data-rates will require increased bandwidth
•Non-NASA demands for bandwidth mount pressure on available radio frequency spectrum allocations
** DSN Future : A User Perspective, Dr. Les Deutsch, Deputy Director, Interplanetary Network Directorate, JPL, DSN 50th Anniversary Celebration Symposium, https://descanso.jpl.nasa.gov/dsn50th/dsn50th.html
•Capabilities
−Streaming HD imagery
−Light Science
−Human Exploration of Deep Space
EARTH-ORBITAL
•Occultation
•Ranging
•Interferometry
Streaming from MARS surface
assets
38

39. © 2024 California Institute of Technology Government sponsorship acknowledged.
Link Acquisition
•A key function of the Flight Subsystem (FS) is to control laser beam pointing from space
•Starts with beacon acquisition by FS
−Achieved by a three-step process
−At the end of this process FS line-of-sight is stabilized
S/C points
Transceiver to
Transmitter
Atmospheric
Turbulence
Laser beacon assisted link acquisition
Transmit Laser to
illuminate spacecraft
1
3
2
DSOC FS scans
spacecraft
uncertainty to
find and “lock”
on beaocn
1064 nm
Knowledge
Uncertainty
Control
Uncertainty
DSOC scans
s/c pointing uncertainty
to find beacon signal
39

40. © 2024 California Institute of Technology Government sponsorship acknowledged.
Uplink Laser Transmitter0 200 400 600 800 1000
-20
-15
-10
-5
0
5
10
TIME (ms)
NORMALIZED IRRADIANCE (dB)
IRRADIANCE AT MARS 1BEAM(blue) vs 8BEAMS(red)
Simulated irradiance
1 beam
8 beams
•Multi-Beaming of uplink to mitigate atmospheric turbulence induced fading
•Plan to use 10 lasers each outputting 500 W to achieve > 5kW average power
−Required to deliver sufficient irradiance at farthest
40

41. © 2024 California Institute of Technology Government sponsorship acknowledged.
Flight Subsystem
Family Portrait
Laser Transmitter Assembly (LTA)
•New technology development
Stationary Electronics Module (SEM)
•Reuse of JPL Universal Space Transponder
(UST) slices
•Custom firmware and software
•Interfaces to spacecraft
Optical Transceiver Assembly (LTA)
•SiC primary, secondary and metering structure
•Photon Counting Camera at focal plane
•PAM on transmit channel (not shown)
Photon
Counting
Camera
DSOC Accommodation Kit (DAK)
•Thermal and contamination
enclosure
•Houses
•Isolation Pointing Assembly
•Launch Locks
•Docking Mechanism
•Spacecraft interface plate
Photon
Counting
Camera
Optical Transceiver
Assembly
41

42. © 2024 California Institute of Technology Government sponsorship acknowledged.
A little bit of math (1 of 2)
•Telecommunication are governed by a link equation
FLIGHT SUBSYSTEM (FS)
Emitted Isotropic Radiate Power
(EIRP)
????????????????????????&#3627408465;??????????????????&#3627408464;&#3627408466;=(??????
??????????????????_????????????×
????????????×??????
????????????×
??????&#3627408476;??????&#3627408475;????????????&#3627408475;??????×
??????????????????????????????×
????????????&#3627408474;.)/Area
( Inverse Distance)
2
loss
Laser
Power Efficiency
Gain
( Beam
Divergence
2
)
Pointing
Loss
Space Loss
Atmospheric
Loss
Beam-Divergence
~ 2*/D
~ 15 µrad
Laser
??????
??????????????????_???????????? @  = 1550 nm
D = 22 cmTransceiver
P
avg_Tx  
Tx
Fiber-core dia. 10 micrometers
Average Human Hair dia. ~ 50 micrometers
FLIGHT SUBSYSTEM (FS)
Emitted Isotropic Radiate Power (EIRP)
Space
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0
500
1000
500
1000
05001000 500 1000
Peak Irradiance 4.7E-13 W/m
2
A little bit of math (2 of 2)
•Telecommunication are governed by a link equation
~2000 Km
from 1 AU
GROUND SUBSYSTEM (GS)
Collection
Efficiency
P
avg_Rx = Irradiance Rx_Area  
Rx P200-inch telescope was largest Rx_Area accessible for DSOC
•Use spacecraft Earth distance of 1 AU in this example of irradiance distribution
Ideal
2-dimensional
Irradiance
distribution
on the ground
Irradiance distribution
shown as a 1-
dimensional point spread
function
Pointing Loss

Pointing
43

44. © 2024 California Institute of Technology Government sponsorship acknowledged.
GLR Technologies: Ground Signal
Processing Assembly (GSPA)
GLR Signal Processing Assembly
GSPA Monitor & Control
Ephemeris predict data Detector centroid estimate
To GLR Monitor and Control To GLR Optics Assembly
Time and Frequency Reference:
Brandywine NFS-220
Data Storage:
Dell R740/MD1420
Signal Processing Modules:
Xilinx VCU-118
…
Time to Digital Converter (TDC):
DotFast TDM800+Supermicro-
based Control Computer
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GLR Optics
•GLR Optics couples coude path to comm detector
−Built-in acquisition channel and steering control
−Actuators to maintain signal spot on detector during tracking
−Compensate for tracking drift and other perturbations
45