Goddard Space Flight Center

CubeSat Communication and Frequency Past Practice and Current Trends

Scott Schaire

NASA Goddard Space Flight Center

Near Earth Network Wallops Station Director

Deputy Project Manager Space Communication and Navigation (SCaN) Network Integration Project

Contributions from Wayne Powell, Serhat Altunc, Felipe Arroyo, Scott Galbraith

May 2014

GSFC Compact Radiation belt Explorer (CeREs) Principal Investigator Shri Kanekal holds an early version of one of the mission’s solid-state detectors – demonstrates a shift in the paradigm for satellite development

Goddard Space Flight Center

Agenda

• History and Trend of CubeSats• CubeSat Communication Evolution• Frequency Licensing Approach• Satellite Communication Bands• CubeSat Radios and Antennas• Ground Stations• Considerations for the Future

MIT’s Micro-sized Microwave Atmospheric Satellite (MicroMAS)

demonstrates an increase in science sophistication of CubeSats

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Goddard Space Flight Center

History and Trend of CubeSats

• CubeSats are in a class of small research spacecraft called picosatellites

• Over 100 Cubesats have been launched into space since they were first introduced by California Polytechnic State University and Stanford University in 1999

• Even though scientists and technologists desire higher data rate communication, CubeSat teams have limited their data transmitted and compromised their science objectives to be compliant with low-cost proven CubeSat radios, antennas, and ground stations

• Current state of the art ~3 Mbit/sec• Future capability ~100 Mbit/sec

A 1U CubeSat, 4” Cube weighing about 2 lbs

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Goddard Space Flight Center

History and Trend of CubeSats Continued

• The NASA CubeSat Launch Initiative has made CubeSat launch slots available on DOD and NASA launches

• A 6U CubeSat is the largest satellite today that could be launched for free

• The National Science Foundation (NSF), NASA and other government organizations are increasing investment in CubeSat projects

• Single CubeSat missions are typically a demonstration for future constellations

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University of Colorado Boulder and the Laboratory for Atmospheric and Space

Physics Miniature X-ray Solar Spectrometer (MinXSS) 3U CubeSat recently funded by

NASA

Goddard Space Flight Center

National Science Foundation CubeSats

• Selected On-Orbit Missions• Cubesat for Ions, Neutrals, Electrons, MAgnetic fields (CINEMA 1)

– UC Berkley, Kyung-Hee U., Imperial College, APL, Inter-American U. of Puerto Rico

• Mission complements RBSP spacecraft. Launched 9/13/12• Firefly/FireStation – GSFC, Hawk, Siena College

• ISS FireStation launched 8/3/13. Firefly launched 11/19/13 • Firebird – Montana State, U. of New Hampshire, Aerospace

Corporation• Launched 12/5/13. Complements balloon-based BARREL

• Selected In-Work Mission• Composition Variations in the Exosphere, Thermosphere, and

Topside Ionosphere (ExoCube) - SSI, Cal Poly, U. of Wisconsin, GSFC, and SRI

• Contains Goddard Improved Winds-Ion-Neutral Composition Suite

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Goddard Space Flight Center

Firefly CubeSat Mission

• Firefly, an NSF-funded mission, was developed by Goddard/Doug Rowland, Hawk Institute for Space Sciences, & Sienna College

• Mission: Determine linkage between lightning & Terrestrial Gamma-Ray Flashes by combining gamma-ray/electron scintillation detector, VLF receiver, & photometers for first simultaneous measurements of lightning & TGFs from a single platform

• Launched on ORS-3, (Minotaur I) from WFF on 11/19. First contact made on 1/6. Spacecraft performing science

• Goddard/WFF ground station team persistently worked through 25 other elements

• Future missions considering low-data rate beacon

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Goddard Space Flight Center

Typical CubeSats

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Goddard Space Flight Center

Typical CubeSat Schedule

IDTask Name

1...Selected Key Milestones2... Kick-off Meeting3... Requirements/Design Review4... Testing/Mission Operations

Review5... Pre-Ship Review6... Launch7...8...Spacecraft Development9... Prelliminary Design1... Bus Assembly and Integration1...1...Payload Development1... Payload Design1... Payload Test1...1...Integration and Test at GSFC1... Environmental Test1...

1...Ground Segement Finalization2...2...Wait for launch2...2...Mission Operations2...2...Data Analysis

Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4Year 1 Year 2 Year 3 Year 4 Year 5 Year 6

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Goddard Space Flight Center

CubeSat Communication Evolution

• About ten years ago, when CubeSats began, they were nothing more than simple science experiments, typically consisting of a camera and a low data rate radio

• Government-funded CubeSats using amateur radio frequencies may violate the intent of the amateur radio service and it is a violation of National Telecommunications Information Administration (NTIA) rules for a government-funded ground station to use amateur radio frequencies to communicate with CubeSats

• The National Science Foundation (NSF) was interested in finding a suitable government frequency band for CubeSats and Utah State worked with L-3 for a UHF CubeSat radio

• Currently, there is an effort to design a system using X-band for CubeSat support with more efficient and complex modulation and encoding schemes to address the CubeSat community’s increasing needs

Antares lifts off from Goddard/Wallops Flight Facility (WFF), with 3 CubeSats onboard in April 2013. NASA CubeSat

Launch Initiative began in 2010

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Goddard Space Flight Center

Frequency Licensing Approach

• Universities and other non-federal US entities continue to use amateur radio frequencies for CubeSats because it is the least expensive and easiest approach for low data rate communication

• The process for coordinating amateur frequency usage requires a relatively simple frequency coordination request form and short lead time

• There are numerous downsides to using amateur and experimental radio frequencies

• US Federal Government CubeSat projects must apply through their funding agency for Spectrum Certification and Frequency Authorization with the NTIA and cannot use non-government processes

GSFC Firefly CubeSat licensed through NTIA

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Goddard Space Flight Center

Satellite Communication Bands

• As the frequency increases from UHF to Ka-band, the potential for higher data rates also increases and the potential for absorption by the atmosphere increases

• Today’s CubeSats mostly operate at UHF and S-bands

• Cases allowed on special case, non-interference, unprotected, secondary basis

• Firefly• Downlink: 400.15-401 MHz• Uplink: 449.75-450.25 MHz

• Utah State University Dynamic Ionosphere CubeSat Experiment (DICE)

• Downlink/Uplink: 449.75-450.25 MHz

• GeneSat• Downlink/Uplink: 2.4 GHz, ~437

MHz

ARC GeneSat CubeSat – 1st CubeSat launched in the US – Dec, 2006, from

GSFC/Wallops Flight Facility

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Goddard Space Flight Center

Satellite Communication Bands Continued

• NASA Space Communication and Navigation• Near Earth Network

• S, X, Ka • Space Network

• S, Ku, Ka• Deep Space Network

• S, X, Ka

Near Earth Network McMurdo Ground Station

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Goddard Space Flight Center

CubeSat Radios and Antennas

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Goddard Space Flight Center

Wallops UHF CubeSat Groundstation

• Specifications• Beamwidth: 2.9 degrees• Frequency Range: 380 to 480 MHz• Secondary Frequency Band: X-Band available

for future high data rate CubeSat communication• Antenna Main Beam Gain: 35 dBi• Diameter: 18.3 meters (60’)

• UHF Radar as a CubeSat Groundstation• 1st used with Utah State University Dynamic

Ionosphere CubeSat Experiment (DICE)• Interference• Morehead added as a back-up

• Cutting-Edge CubeSat communication over a government-licensed UHF frequency allocation that enables high data rates (3.0 Mbit/Sec)

• Currently communicating with Firefly spacecraft• Slated for use for MiRaTA, MicroMAS, CeREs,

HARP, MinXSS, and many proposed CubeSats

Wallops UHF on left, S-Band on right

Morehead State University 21 Meter antenna

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Goddard Space Flight Center

Near Earth Network Compatibility

• 11 Meter class dishes yields high gain

• Link budget shows 12.5 Mbps can be done in low Earth orbit with a 1 Watt output satellite transmitter

• LASP and Goddard/Wallops Flight Facility have partnered to design a CubeSat X-Band transmitter, S-Band receiver (NEN compatible)

• MSFC engineers are also advising on the project.

• Project funded by NASA Space Technology and Mission Directorate (STMD)

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Near Earth Network Alaska Satellite Facility 11 Meter class antennas

Goddard Space Flight Center

NASA Owned and Partnered Network Available to NEN

Station Name Location Assets and Service Types NASA Owned or Contract

Wallops Ground Station Wallops, VA 11.28 m X/S-band; 5 m S-band; VHF (2) NASA

White Sands Complex White Sands, NM 18 m Ka/S band; VHF NASA

McMurdo Ground Station McMurdo Base, Antarctica 10 m X/S band NASA

Alaska Satellite Facility Fairbanks, AK 10 m, 11.28 m and 11 m X/S band NASA

Launch Communication Systems Ponce De Leon, FL and Kennedy Space Center, FL

6.1 m S-band (2) NASA

NOAA Fairbanks Command and Data Acquisition Station

Gilmore Creek, AK 13 m X/S band (3) Partnered

Kongsberg Satellite Services Svalbard, Norway 11m X/S band; 13 m X/S Band (w) Contract

Singapore, Malaysia 11 m X/S band Contract

TrollSat, Antarctica 7.3 m X/S band Contract

Swedish Space Corporation Kiruna, Sweden 13 m X/S band (2) Contract

Universal Space Network North Pole, AK 11 m S-band; 5 m S-band, 11 m X/S band; 7.3 m X/S band

Contract

Dongara, Australia 13 m S-band Contract

South Point, HI 13 m S-Band (2) Contract

SSC/Santiago, Chile Santiago, Chile 9 m S-band; 7 m S-band Transmit; 12 m S-band Receive

Contract

Council for Scientific and Industrial Research

Hartebeesthoek, South Africa 12 m S-band Receive; 6 m S-band Transmit Contract

German Space Agency Wilheim, Germany 15 m S-band Contract

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Goddard Space Flight Center

X-Band Considerations

• Universities may have a desire to create their own ground network

• NEN X-Band ground system is already standardized

• Standardization of CubeSat radios and ground networks may reduce frequency authorization time

• Standard hardware will streamline compatibility testing

• Developers can focus on end use and maximize science “bang-for-the-buck”

Goddard/Wallops LunarCube with deployable X-band antenna based on University of Colorado/Goddard X/S band CubeSat Radio and Near Earth

Network

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Goddard Space Flight Center

Future Considerations

• TDRSS• Use of geosynchronous relay satellite provides greater flexibility in

mission planning• Global communications coverage • Low latency

• CubeSat Intersatellite Link• Signal must be robust against interference from other satellite

exchanges• Increasing Data Rates

• Ka band could provide even higher data rates and is compatible with Near Earth Network

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