cal poly slo 13th annual cubesat developers workshop 21...

Planet Labs Ground Station NetworkBryan Klofas

bryan@planet.com21 April 2016

13th Annual CubeSat Developers WorkshopCal Poly SLO

• Planet Labs is driven by a mission to image the entire Earth every day, and make global change visible, accessible, and actionable

• 300+ employees• Based in San Francisco, CA

○ Satellite offices in Lethbridge and Berlin (RapidEye)• $183 Million in VC funding

• 133 satellites successfully launched• 2 rocket failures with 34 satellites lost (Orb-3, SpaceX-7)• 100 satellites successfully deployed• 32 satellites launched and waiting on ISS (Orb-4, OA-6)• 36 satellites still in orbit

Intro to Planet LabsSpace Startup

Slide 2

• 3U form factor with 6 fold-out panels• CCD camera• 20km swath width at 3.5m GSD from 400 km• Onboard JPEG2000 compression• 13 Hardware Revisions• COTS SSD• Ubuntu

A Typical SatelliteBasics

Slide 3

• UHF radio: TI wireless MCU• Power amplifier: RFMD 1 watt output• Monopole antenna

• Ground station is identical hardware and software• Presented at CubeSat Summer Workshop 2014

○ Design will be open-sourced soon (up and downlink encrypted and secured)

○ Follow-up presentation at SmallSat 2016

A Typical SatelliteUHF Radio

Slide 4

• S-band uplink○ 250 kbps BPSK○ NACK-based file protocol○ Needed for downlink ACM

• X-band downlink○ 12.5 Mbps up to 100+ Mbps○ 8.2 GHz at 2 watts○ DVB-S2 standard with Generic Stream Encapsulation○ Fixed 24 Mbaud symbol rate

■ Upgrade to 56 Msps on next sats○ Variable modulation: QPSK, 8PSK, 16APSK, 32APSK ○ Variable FEC: 1/4 up to 9/10○ GSE allows IP connectivity to satellite

A Typical SatelliteS/X Radio

Slide 5

• “Spaceship Captains” operate all satellites○ Mostly anomaly resolution and testing○ Normal operations: “Automate ourselves out of a job”○ If they all call in sick, everything still works (for a few days)○ 24/7 on call support for emergencies

• Mission Control is fully automated, runs on AWS○ Scheduling happens frequently○ All software done in house, allowing us to fix bugs quickly○ No existing products fit our needs

• System is fully automated and tolerant of missed passes○ Greatly reduced operational costs vs. 100% downlink

guarantee○ Missed data is downloaded next pass○ Decreased operational costs allow smaller team to manage

satellites and have a “normal” life (no graveyard shifts)○ Continuously developing/updating software

Satellite ControlOpen 9am-5pm M-F

Slide 6

• TT&C only• Uplink at 450 MHz, up to 100 Watts• Downlink at 401.3 MHz• Encrypted 4800 baud GFSK• Yaesu G-5500• Separate M2 yagis• Open-source radio design

A Typical Ground StationUHF

Morehead State University

Slide 7

• When not scheduled to talk with a satellite, each ground station opportunistically ranges with all available satellites

• Post processed errors at 1 day:○ JSpOC: 1 to 3km○ UHF ranging: 0.5km

• Ranging data fed back into Space Data Association

• Open orbit data at http://ephemerides.planet-labs.com

• See AAS 15-524, “Orbit Determination and Differential-Drag Control of Planet Labs CubeSat Constellation,” by Cyrus Foster, Henry Hallam, James Mason

A Typical Ground StationUHF Ranging

Slide 8

• 5m dish• Combined S/X feed• Up to 100 W S-band uplink• 29 dB/K at X-band• Integrated UHF feed on

other dishes• Dektec PCI DVB-S2

receiver card

A Typical Ground StationWashington State

Brewster, Washington

Slide 9

• 55 degree max elevation• X-band lock for 435 seconds = 7.25 min• Variable data rate up to 84 Mbps• Modcod up to 24• Downloaded: 4.2 GBytes = 650 pictures = 170k sq km *• Pictures uploaded to AWS for rectification

A Typical PassWashington State talking with Flock 2b, March 16th

* Including frame overlap, clouds, ocean, etc. Only 20-50% of downloaded pics are acceptable for consumers

Slide 10

An Average DayNew Zealand schedule for March 16th UTC

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Slide 11

• 33 passes scheduled for 16 satellites• 25 passes successful, 75%

○ Satellite not transmitting or pointing correctly, ground station pointing error, software bugs

• 99 GBytes downloaded = 23k pictures = 6M sq km *

An Average DayNew Zealand on March 16th UTC

Slide 12

The Ground Station NetworkGlobal View

• 7 CGC 5m dishes• 7 Omnispace/ICO 7.6m dishes• 4 L3 Datron 5m dishes• 32 yagi stations

HSD + LST

Slide 13

A Typical DayGlobal View

Colors indicate ground station

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Slide 14

A Typical DayMarch 16th UTC

● UHF:○ 333 passes scheduled, 239 good passes, 71%○ 97k commands received

● X-Band:○ 207 passes scheduled, 157 good passes, 76%○ 559 GBytes downloaded = 161k pics = 39M sq km *○ CONUS is 8M sq km

● Best day: 777 GB

Slide 15

• Image all the earth, every day• 6 TBytes of land images to download every day

○ Equipment already installed in Iceland○ More locations to come later this year○ Continuous improvement process○ Increasing downlink rate past 75% allows

us to download oceans, ice, etc

Mission 1Image all land, every day

Slide 16

Questions?