optical crosslinks for cubesats - nasa · 2017-10-12 · • tvac and radiation testing of edfa •...

SBIR Data Rights ApplySeptember 13, 2017

Optical Crosslinks for CubeSats

September 13, 2017J. Hanson*, CrossTrac Engineering

K. Cahoy, MIT

*(408)[email protected]

These SBIR data are furnished with SBIR rights under Contract No. NNX17CG37P. For a period of 4 yearsafter, unless extended in accordance with FAR 27.409(h), after acceptance of all items to be delivered underthis contract, the Government will use these data for Government purposes only, and they shall not bedisclosed outside the Government (including disclosure for procurement purposes) during such periodwithout permission of the Contractor, except that, subject to the foregoing use and disclosure prohibitions,these data may be disclosed for use by support Contractors. After the protection period, the Government hasa paid-up license to use, and to authorize others to use on its behalf, these data for Government purposes,but is relieved of all disclosure prohibitions and assumes no liability for unauthorized use of these data bythird parties. This notice shall be affixed to any reproductions of these data, in wholeor in part.

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CubeSat Optical Crosslink Terminal

• Phase I STTR

• CrossTrac Engineering

• MIT AeroAstro Lab

– Professor Kerri Cahoy

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CrossTrac Engineering, Inc.• Established 1999

• Engineering development and support in:

– Small spacecraft design

– Systems engineering

– Control system design

– XNAV & XTIM

• Typical Work Breakdown:

– Aerospace – 75%

– Industrial – 25%

ADCS Design

Laser Scanning Microscope X-ray Navigation

CubeSat Swarms


Optical Crosslinks for CubeSats

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• Constellation Support• High data rate crosslink (> 100 Mbps)

• Space-to-ground downlink

• Possible low-cost ground stations

• Swarm Missions• Multiple spacecraft performing time synchronized

operations to provide system functionality

• Ranging & time transfer important

• Synthetic aperture radar

• Multi-point tomographic measurements

• Large sparse array telescopes

• Currently exploring mission options to drive basic terminal requirements


Beacon receiver

Fast steering mirror (FSM)

Fiber Amplifier (under tray)

PCBs

Fiber Tray

Scope Low-cost CubeSat payload

Architecture Direct detection MOPACOTS telecom parts (1550 nm)

Downlink data rates

10 Mbps (amateur telescope)100 Mbps (OCTL)

Power 200 mW Tx< 15 W during Tx

Beamwidth 1.3 mrad HPBW (initial experiment)

Modulation PPM

Coding RS(255,239)

Mass, volume 1.0 kg, 1 U

Control architecture

● Bus coarse pointing (<0.5°)● FSM throw (+/- 3°)● Beacon receiver (976 nm) for

pointing knowledge (20 arcsec)

11 cm

Beacon receiver

D. Barnes, M. Khatsenko, MIT

9.6 cm

Dichroic

FSMCOTS Collimator

1” aperture

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Data dlinkBeacon ulink

NODE: Nanosatellite Optical Downlink Experiment


E. Clements, K. Riesing

[4] Yoon, H., K. Riesing, and K. Cahoy. "Satellite Tracking System using Amateur Telescope and Star Camera for Portable Optical Ground Station.” SmallSat 2016.

Downlink with JPL OCTL telescope:

Data rate 10 - 50 Mbps

Rx Diameter 30 cm

Detector Direct detection w/ COTS Voxtel APD

Receiver electronics Custom data acquisition system

Pointing COTS IR camera and star tracker [19]

FSM to keep spot on APD (no AO)

Uplink beacon 976 nm (OCTL) beacon[20]

Downlink with NODE amateur telescope

FSM

APD

Beam splitter

IR camera

Data rate 50 - 100 Mbps

Rx Diameter 1 m

Detector Direct detection w/ COTS Voxtel APD

Receiver electronics Custom data acquisition system

Uplink beacon 976 nm, 10 W tx power, 1 mrad beam

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Recent MIT Accomplishments• < 1arcsec, 1-sigma pointing control

w/MEMS FSM vs. 40” 1-sigma CubeSatdisturbances (H. Yoon, Ph.D. 2017)

• Internal MEMS FSM feedback calibration laser tracking beacon (O. Cierny, visiting MS 2017)

• TVAC and radiation testing of EDFA

• Flight electronics boards and structures for downlink module

• Control software for alignment of and LEO tracking with COTS telescope

• Over the air testing of modulation, coding, and interleaving and clock recovery; also GS peak power tracking (Ziegler, SM 2017, Riesing Ph.D. 2018)

• Detailed design and simulation of monostatic crosslink terminal (Long, SM 2018, Morgan SB 2018)

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One RTD on each face

EDFA in TVAC


Phase I STTR Objectives• Continued development of MIT concept to CubeSat

crosslinks• Development of performance requirements

– Development of Reference Missions– Optical terminal– Omni-RF backbone & network software– 3U vs. 6U trade

• Preliminary design of optical terminal– Review of current MIT design and technology development plan

• Development of Concept of Operations– Initialization, maintenance and operation of optical/RF network

• Network control software

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Michael Long, MIT

Scope Monostatic

Architecture Direct detection MOPA~1565 nm, 976 nm beacon, 635 nm cal

Transmit divergenceTransmit beam size

+/-0.07 mrad (FWHM)16 mm (1/e2 Gaussian diam.)

Power 200 mW Tx , 500 mW beacon

Acq/Rx entrance aperture 20 mm

Telescope magnification 10.5x

Tx small beam sizeAcq/rx small beam size

1.6 mm2.0 mm

Max dimension 106 mm

Quad cell FOV (acquisition)Quad cell linear range (acq)

+/-0.5°+/-0.15°

Beacon spot size on quad cell 1 mm

Data rate, range 20 Mbps at > 1000 km

Implementation of NODES for Crosslinks

Rachel Morgan, MIT


RF Network RadioUHF Radio• Baseline supplied by GMH

Engineering• Software Defined Radio• Includes two-way range/time transfer• UHF / Omni coverage

Network Software Stack

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• Developed by CrossTrac• Includes multi-hop messages,

fragmentation and topology discovery• Includes MATLAB simulation of

operations


Network Simulation

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GUI Interface Graphical Output


Summary• Optical crosslinks are critical to the development of CubeSat

swarms– High data rate, precision time transfer

• Optical terminal with FSM approach offers a low power, high performance option for optical communications

• The CrossTrac/MIT team is continuing the development and implementation of this technology

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Thank You for Your Attention!

• Questions?

• Contact:

– Dr. John Hanson

[email protected]

408-898-0376

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mailto:[email protected]

optical crosslinks for cubesats - nasa · 2017-10-12 · • tvac and radiation testing of edfa •...

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